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bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.3.3 Model including Lawful Interception | Figure 16 illustrates the scenario with Lawful Interception (LI) included. It also depicts the situation where a user communicates with another user directly via satellite, possibly via an inter-satellite link. Entities like satellite operation and network operation are included, as these are relevant with respect to LI. In this figure, the domains are given brief names, so that it is possible to construct interface names indicating i.e. the L1-A1, the N1-M1, M1-S1 interface etc. The figure here illustrates the number of possible interfaces and thus the potential complexity involved in implementing LI, as an interceptor needs to have access not only to the traffic data, but also call records etc. A2: Satellite A A2: Satellite B A1: Gateway A A1: Terminal B U2: Application & Equipment N1: Core Network O2: Network Operation M1: Management O1: Satellite Operation C1: Content Provider S1: Service Provider U1: User L1: Lawful Interception A3: Terminal A A3: Gateway B Figure 16: Logical relationships including Lawful Interception |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.3.4 UMTS/3GPP Network Model | The UMTS / 3GPP reference model emphasizes the location management aspect. The terms mobility management and location management imply the same thing with respect to BSM, which is determining a user's location in the network (i.e. the beam they are in). Detailed models can be found in the 3GPP documents, which illustrate details of the location management concept. It is the fixed-mobile convergence trend that motivates introducing the UMTS reference model. While BSM systems can of course be mobile, given suitable technology, it is also worth noting that even when the terminals are fixed, users can roam between different terminals with a subscriber identification card/module (SIM) similar to or possibly the same as in UMTS. Which service provider a SIM card is associated with will depend upon the service provider scenario. Location management may be required for BSM systems, and in such a case it should be based on already developed and proven concepts. This implies that requirements for satellite systems must be integrated into IN-nodes and databases in the GII. UMTS is more suited for data and mobile multimedia than GSM. For instance, with UMTS it is possible that data traffic can be routed via UMTS, while voice can be kept in GSM. This is a likely scenario, at least for a transition period. The model reflects this by having the ability to route the received data into the PSTN network or into the general GII for e.g. Internet traffic. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 106 It is also worth noting that the UMTS reference model can be mapped onto the four-domain structure, as shown in the lower part of Figure 17. Internet Domain GII PSTN Domain [_u] Cu Uu Iu Yu Zu [_u] User Equipment Domain Infrastructure Domain Core Network Domain Mobile Equipment Domain USIM Domain Access Network Domain Serving Network Domain Transit Network Domain Home Network Domain Note that if the other party is on the same network, then no particular instance is activated in the Transit Network Content/ server GII/ Core Network Access Network User/ Customer Figure 17: The UMTS and 3GPP network model |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4 Access Network (AN) Architectural Models | The most important application of BSM systems is to provide broadband access directly to end users, and therefore the satellite network normally acts as an access network. As such it is relevant to identify the reference models already being used within other bodies for access network architectures. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4.1 ITU-T Work on Satellites in Access Network | ITU-T Recommendation G.902 [24] is a framework recommendation on the architecture and functions of access networks. It describes access types, management and service node aspects. An AN as defined by ITU-T Recommendation G.902 [24] is bound by User Network Interfaces (UNI) at the customer side and Service Node Interfaces (SNI) at the core network side and does not interpret user-network signalling. ITU-T Recommendation G.902 [24] builds on the concepts that were developed in ETSI in the context of the narrowband SNI (V5) to encompass also broadband access networks (VB5). ITU-T activities on Access Networks are carried out by various SGs under the lead of SG15. SG15 has allocated the co- ordination of work on Access Networks to Q.1/15. The ITU-T model also comprises the 4 main components ITU-T: • Service Function: such as Video Server and Video Service Provider for video service; • Core Network: such as Telecommunication Network, PSTN, N-ISDN, B-ISDN; • Access Network: such as CATV Network, ADSL/VDSL, Fibre Network, RITL, Satellite; • CPN (Customer Premise Network): such as Access Unit, TV, PC, Phone, Wireless Phone. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 107 The various interface reference points are: • SNISn: between Service Function and Access Network (n - seq. number); • SNICn: between Core Network and Access Network ( n - seq. number); • XNIXXn: between Access Network and CPN (x: type of access technology/medium); • Ln: between Access Networks; • Qn: between Access Network and Management Agent/Network. The following XNIXXn were identified in the scenarios: • XNICPn For copper interfaces (e.g. UNI for ISDN); • XNICXn For Coax interfaces (e.g. CATV); • XNISAn For Satellite interfaces (e.g. ptp or broadcast); • XNIWIn For wireless interfaces (e.g. RITL); • XNIOPn For Optical (Passive) interfaces (e.g. BPON); • XNILAn For LAN interfaces (e.g. 10-BASE-T). The following scenario describes B-ISDN, Internet and mobile communications services that are supported by satellite networks and the pathways by which they can be delivered to the customer premise. Video and broadcast services via satellite are not part of this scenario. B-ISDN Satellite networks capable of supporting B-ISDN can deliver full asynchronous transfer mode services either directly to a customer premise earth station ("access unit") or via a gateway earth station which is not customer equipment. The same satellite system can carry B-ISDN traffic to and from a terrestrial carrier network through such a gateway. These paths are represented by the set of reference points LA, XNISA1, SNIC8 and XNICP5. Depending on the characteristics of the satellite network, key interfaces may be present at points SNIC8, XNICP5. These interfaces maintain end-to-end ATM quality of service parameters between the satellite and terrestrial carrier networks or between the satellite network and the Customer Premise network (CPN). Internet In the case of the Internet backbone satellite network, the Internet service provider uses the satellite network to deliver Internet traffic either directly to the customer premise or to a shared gateway. This service is represented by reference points LB, XNICO5 and XNISA1. Since certain TCP/IP flow and congestion control protocols can perform relatively poorly over high-delay links, key interfaces may be present at reference points LB, XNISA1 and (possibly) XNICO1 to provide optimal TCP/IP interworking between the satellite and terrestrial network pathways. Mobile Satellite Services Mobile satellite systems provide voice, fax and low-rate data services to the customer. Several service pathways are indicated by reference points XNIWI3, XNIWI1, LF, SNIC8, XNICO5, XNICO1, and XNISA1. In this case, traffic to and from the mobile user appliances flows into the mobile-satellite service network (XNIWI3, XNIWI1). From there it can be delivered to customer premises via several possible paths (for example, through XNISA1, or LF - SNIC8- XNICP1). The speech compression techniques typically used in mobile services may indicate a need for key interfaces between the mobile appliance and the fixed appliance in order to maintain voice quality of service. Candidate reference points for this type of interface are XNISA1, XNICP5, SNIC8and/or XNISA1. It should be noted that several combinations of these services can be supported by this scenario (e.g. mobile Internet); however, for purposes of brevity they are not discussed here. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 108 NT- function Core Network (B-ISDN) Access Network [SAT] Access Network [Gateway] Access Network [B-ISDN] SNIC8 SNIC1 ISA1 L XNISA1 XNICP5 J XNIWI4 Access Unit [SAT] Access Unit [B-ISDN] PC Phone Video CPN Wireless Phone XNICP1 XNIWI3 XNIWI4 XNISA1 L F ISP port server L B XNIS A1 Access Unit (Gateway Earth Station) Access Network PSTN or ISDN Switch LA SNIC1 XNICP5 XNICP1 XNICP1 Logical Presentation Physical Presentation SNIC8 Telecommunications Network XNISA 1 Phone PC Video Access Unit (s) CPE Mobile Satellite Network BISDN Satellite Network Figure 18: Access Network Transport - Access using satellites scenario |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4.2 FSAN | The Full Service Access Network Initiative (FSAN) has produced a specification focusing on access elements. It is divided into the following sections: • Services and deployment - the first two sections explain the dimensioning and; • Architecture and performance - performance requirements of the common access elements; • Transport; • Infrastructure - physical realization requirements; • Signalling and control - access specific requirements; • Operations, Administration, and Maintenance. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4.2.1 FSAN Architecture | The most important result from the Full Service Access Network Initiative is the recognition that all operators require the same elements in their access network, as shown in the generic FSAN architecture below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 109 SN Extended Feeder OLT ODN ONU NT ONT Access Network SNI User UNI Figure 19: Generic FSAN Architecture The key components in the generic FSAN architecture are: • The Service Node (SN), which is the network element that provides access to the various switched and or permanent telecommunications services. For switched services the SN provides call control, connection control and resource handling functions. • The Access Network (AN), which refers to the equipment used to provide the transport capability for the provision of telecommunication services between a Service Node Interface (SNI) and one or more associated User Network Interfaces (UNI). User signalling is carried transparently by the AN. • The Extender Feeder, which can be used to provide the physical resources to extend the AN over larger distances. • The Optical Line Termination (OLT), which provides the network side interface of the AN. An OLT can be connected to more than one ODN. • The Optical Distribution Network (ODN) refers to the point-to-multipoint fibre network used to transport services in a common format from the OLT to the ONU/ONT. The ODN may consist of Passive Optical Networks (PONs). • The Optical Network Unit/Termination (ONU/ONT) provides the customer side-interface of the AN. It is connected to the ODN. For some operators the ONU and NT functions will be combined into one physical resource referred to as an ONT. • The Network Termination (NT) is the physical resource which resides in the customer premises and forms the boundary of the AN. This interface is referred to as the User Network Interface (UNI). The NT provides the onward transmission of services over building wiring to Customer Premise Equipment (CPE). The FSAN architecture is based on the delivery of Asynchronous Transfer Mode (ATM) narrowband and broadband services using a selection of drop media to take the required services from the remote node to the customer termination unit. The key drop modes are a combination of fibre and copper Asymmetrical Digital Subscriber Line (ADSL) and Very high speed Digital Subscriber Line (VDSL) for Fibre to the Exchange, Kerb and Cabin, with fibre optic only networks for fibre to the home networks. The major differences come from the positioning of the ONU (Optical Network Unit). Figure 20 below shows the system architectures. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 110 ATM OLT ONU Service Node PON Head End Node Local Exchange Cabinet Kerb Home NTE ATM OLT ONU NTE ATM OLT ONU NTE ATM OLT ONU NTE PON VDSL or ADSL VDSL VDSL UNI FTTCab FTTK/ FTTB FTTB/ FTTH FTTEx VB5 ADSL - Asymmetric Digital Subscriber Line/Loop FTTB - Fibre To The Building FTTCab - Fibre To The Cabinet FTTEx - Fibre To The Exchange FTTH - Fibre To The Home FTTK - Fibre To The Kerb NTE - Network Termination Equipment OLT - Optical Line Termination ONU - Optical Network Unit PON - Passive Optical Network VDSL - Very high-speed Digital Subscriber Line/Loop Figure 20: FSAN Common Network Elements |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4.2.2 SNI and UNI architectures | The FSAN Common Technical Specification specifies the use of V interfaces at the digital SNI for the support of broadband or combined narrow-band and broadband access networks. There are two types of VB interfaces VB5.1 and VB5.2 both standardized within the ITU and ETSI. The functionality of the VB5.1 interface is to: • Define the access type, ATM multiplexing and cross-connectivity in the AN at the Virtual Path (VP) and Virtual Connection (VC) level. This includes the allocation of VPs and VCs. This is required to provide the multiplexed and demultiplexed streams from the UNI to the SNI and vice-versa. VB5.1 supports the use of the ATM layer for user plane, control plane and management plane links. • Define the time critical management functions and real time co-ordination between the AN and the SN. This is achieved through a Real Time Management plane Co-ordination (RTMC) protocol. • Definition of the timing and Operation Administration and Maintenance (OAM) flows between the AN and the SN. This functionality is shown in the figure below. The Ia interface is the VB5.1 interface point adjacent to the AN equipment and the Ib interface is the VB5.1 interface point adjacent to the SN equipment. AN SN Ia Ib VP & VC Links VB5.1 RTMC TIMING OAM Figure 21: VB5.1 Functions ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 111 The following key issues should also be noted: • In VB5.1 the AN transparently passes on any user signalling and charging information directly to the SN. • All call control and associated connection control resides in the SN. • The selection of a Service Provider (SP) by the AN, based on user signalling is not possible since this would require the existence of SN functionality in the AN. • The establishment of VC and VPs in the AN is under the control of the SN at all times. The VB5.1 interface architecture is defined in detail by the ITU and ETSI in documents ITU-T Recommendation G.967.1 [25] and EN 301 005 [12] respectively. VB5.2 provides the additional functionality of been able to establish on demand flexible provisioned VC and VP connectivity in the AN under the control of the SN. This achieved through the addition of a Broadband Bearer Connection (B-BCC) protocol that provides the mechanism by which the SN can request the AN to establish, modify and release VP and VC links on demand in the AN, based on negotiated connection attributes such as traffic descriptors and Grade of Service/Quality of Service parameters. The VB5.2 interface architecture is defined in detail by the ITU and ETSI in documents ITU-T Recommendation G.967.2 [26] and EN 301 217 [14] respectively. With respect to the UNI for the support of broadband access networks, the FSAN Common Technical Specification specifies the use of the latest ATM Forum UNI architecture, presently UNI 3.1 [37]. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4.2.3 FSAN and Satellite Systems | While the FSAN initiative has clearly to date been focussed exclusively on terrestrial optical and wireline technologies, the user applications and the approach to network management can be mapped onto the proposed future broadband satellite systems. Basically there are two options for generic satellite access networks, the first being to use transparent satellites which are capable of delivering packet based services over existing systems using ITU-T Recommendation X.25 [72], ATM, Frame Relay and IP technology and secondly the next generation satellites offering Onboard Processing (OBP) capabilities. With transparent systems the satellite access network can be considered as a bent pipe delivery system since no processing is done above the physical layer. However with the next generation OBP systems the aim is to combine the multiplexing capability of ATM transport with advanced Medium Access Control (MAC) processing on board. With OBP, ATM layer and above processing will be carried out on board the satellite. This principle is nicely compatible with the FSAN architecture, which also assumes an ATM transport platform and performs multiplexing in the access network through the ONU. FSAN further maps onto broadband satellite systems with the key network intelligence being at the SN so that the AN can be managed from the SN. This bodes well for satellite systems since it can reduce the intelligence required on board to the minimum for operational reasons and reliability. One approach to mapping FSAN onto the proposed BSM systems is shown in Figure 22 below. This mapping of FSAN is based on the assumptions that: • a gateway satellite earth station can be considered as the satellite equivalent of an OLT; • the satellite access network can be considered as the satellite equivalent of the ODN with the satellite(s) acting as ONUs; • a remote satellite terminal can be considered as the satellite equivalent of a terrestrial NT unit. The above assumptions can be used for mapping both standard transparent satellite systems and the new OBP proposals. However, the OBP issues needs further investigation since the level of intelligence on-board could move the satellite into areas traditionally addressed at the SN. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 112 ATM OLT ONU NTE Core Network Gateway Function BSM System User Terminal FSAN BSM SNI BSM Operator Service Provider UNI Figure 22: FSAN Applied to BSM To better show the relationship to the basic four domain model, the figure above can be redrawn as in Figure 23 below. This figure also illustrates that both BSM operators and service providers will need to control parts of the terminal and gateways. The precise definitions of these interfaces need to be sorted out. One of the most important issues is the location of the UNI - is this at the user premises as an interface on the User Terminal as depicted in Figure 22, or could it be e.g. at the gateway station? The answer is dependent on the specific satellite system network architecture, and as such it is likely that different scenarios will have to be considered. User Terminal Core Network Gateway Function Satellite System BSM operator Service Provider Figure 23: Redrawing of the FSAN model |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.4.3 Comparison of AN Reference Models | It should be recognized that the choice of external interfaces is as much a commercial and regulatory issue as a technical question. This means that a particular interface may be perceived by one standards group as AN internal, while another group may pursue the same interface as AN external. The undesirable but unavoidable consequence of the classification of interfaces as internal or external is therefore that some interfaces will appear under both. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 113 The figure below shows the reference models that are used in ETSI, the ITU-T, the ATM Forum, DAVIC 1.0 and in DVB. The figure highlights the different terms that are used and their relationship. It should be noted that there is less resemblance between the models than one would think at first sight; this is due to differences in interface and functional definitions. ETSI (DTS/TM-3024) ITU-T (I.413, I.414) ATM CORE NETWORK ATM Access Network ANI UNIX Home ATM Network Distribution Final Drop NT Home UNI UB TE TE ADAPTER R SB ATM FORUM RBB GROUP (95-1416R2) CUSTOMER PREMISES EQUIPMENT (STB) NODE SET TOP UNIT INTERF. UNIT A4 A1 A0 NT DISTRIBUTION NETWORK ACCESS NODE A2 A3 To other Delivery Systems / Services ACCESS NETWORK UPI A1* CORE NETWORK DAVIC (PART 04) B-TE B-NT2 ET VB ACCESS DISTRIBUTION NETWORK B-NT1 U SNI TB SB ACCESS NETWORK UNI Broadcast Network Adaptor Interactive Network Adaptor Interactive Service Provider Broadcast Service Provider Broadcast Interface Module Interactive Interface Module (can be external) Set Top Unit (STU) Forward Interaction Path Return Interaction path Interaction channels Broadcast channel Network Interface Unit (NIU) Set top box (STB) Broadcasting Delivery Media Interaction Network UNI SNI DVB Reference Model for Interactive Systems Figure 24: Access network reference models [8] ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 114 The Digital Audio Visual Council (DAVIC) Specification part 04 gives an overview of delivery system architecture and interfaces. DAVIC has classified networked delivery systems into cabled, hertzian and hybrid networks. The delivery system is partitioned into a core network (CN) and an access network (AN). A number of wired access network types are distinguished. These are referred to by DAVIC as Asymmetric Digital Subscriber Line (ADSL) AN, Very high bit rate Digital Subscriber Line (VDSL) AN, Fibre To The Curb (FTTC) AN, and Fibre To The Home (FTTH) AN. FTTH ANs are assumed to use "active" Network Terminations (NT). The other types may use "passive" NTs. Terrestrial broadcasting networks have also been addressed by a recent DAVIC call for proposals. Asynchronous Transfer Mode (ATM) Forum AF-RBB-0099.000 [38] documents the progress of the work in the ATM Forum Residential Broadband (RBB) working group. It shows the RBB reference architecture and the interfaces for which the ATM Forum seeks specifications. Annex F, entitled "Synergy between Terrestrial and Satellite Broadband Access Proposals and Standards", considers in detail the different approaches to access network standards and their applicability to BSM systems. The objective is to identify areas where ETSI work on BSM system standards could be based on existing recognized and adopted terrestrial access network standards. An overview of the various network architectures and management approaches adopted by industry groups such as the FSAN consortium, the ATM Forum and DAVIC is provided and relationships with ITU and ETSI standards are identified. FSAN is covered in the most detail because it provides a common architecture, interface and network management approach for access networks that could be applied to the BSM case. Areas of synergy and conflict are discussed and a possible way forward for ETSI BSM standards work is proposed. Common Elements After reviewing the relevant standards and initiatives it is clear that the following issues are common and hence should be considered for adoption in any future broadband satellite system proposal: • The use of the ETSI/ITU VB5 architecture at the SNI. • The use of the ATM Forum UNI, NNI and PNNI architectures at the UNI interface. • The use of TMN based manager to manager communications for end to end service management. • The use of some form of RTMC, B-BCC and ITU-T Recommendation Q.2931 [73] signalling. • The common use of physical interfaces and service sets. • The common use of asymmetric and symmetrical services. The above issues are shown schematically in Figures 25 and 26 below, which show the domains and reference points for the various initiatives mapped onto a satellite access network. SNI VB5 UNI ATMF Satellite Access Network UNI (P)NNI VB5.1 RTMC VB5.2 RTMC & B-BCC UNI Service Node Access Switch NT User Core Network Gateway Access Switch Figure 25: Common Interface Domains ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 115 FSAN SNI, VB5 UNI, ATMF ATM-F ANI, VB5 UNI W UNI X DAVIC A9 A4, VB5 A3 A2 A1 A1*, UNI UMTS Yu Iu Uu Cu Service Node Access Switch NT User Core Network Gateway Access Switch Satellite Access Network Figure 26: Cross Interface Signalling Key Differences However, the following differences exist across the various standards and initiatives: • The FSAN approach is based on transparent signalling and no intelligence in the access network. This ideally maps onto present day transparent bent pipe satellite systems, but may raise issues with OBP satellite systems, which generally include some intelligence. FSAN architecture is also based on management from the core network, which is a good approach for satellite applications since it reduces the intelligence needed on board the satellite. • The ATM Forum approach is based on active signalling and ATM layer processing within the access network which may map onto future broadband systems using OBP but is incompatible with present day transparent systems. However the use of signalling proxy agents may be able to resolve this issue by moving the intelligence back to the core network. • TIA activities have identified that a different ATM interface will be required at the satellite to gateway, satellite to satellite and satellite to remote terminal interfaces dependent on the network configuration e.g. ATM interconnect or full mesh architecture and connection between public or private networks. • The DAVIC specification highlights the issue of where to locate the network management and intelligence boundaries for example who manages the user terminal equipment, etc. • Finally there is the issue of running the VB5 RTMC and B-BCC over a satellite access link, i.e. will the round trip access delay effect their operation. Conclusion In conclusion it is recommended that standardization of future broadband satellite systems should consider the use of the ITU/ETSI VB5 and ATM Forum UNI interfaces at the Service Node and Access Node Interfaces of their networks since these architectures are common across all the various standards. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.5 Terminal | This subclause details interfaces in a possible terminal. The modules found are in this case include a User Identification Module, UIM, Terminal Operational Support Systems (OSS), Access management, access unit, middleware and other general terminal functions. One could easily also introduce more interfaces, such as for example between the indoor and outdoor unit. The interfaces named are those that are found in GSM/UMTS. A possible standardization process may decide to work on only some of these interfaces and not on others. I.e. a UIM has to comply with standards if standard modules from UMTS are to be used. Applications outside the terminal, like a browser, may need a standard way of interfacing with the middleware domain. An implementation of for instance FSAN allowing different service providers on different systems to manage terminals consistently will require some standard related to management. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 116 UIM Terminal Access Unit(s) UMTS ATM ISDN etc. Access Network Domain Application Middleware Cu Uu/ Wu API [TBD] Terminal OSS Access Mgmnt. Figure 27: Candidate reference model for BSM terminal 10.6 Management Model |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.6.1 TMN Layered Architecture | The ITU's Telecommunications Management Network (TMN) layered architecture, defined in ITU-T Recommendation M.3010 [29], is shown schematically in Figure 28. The Network Element Layer (NEL) contains the physical resources called network elements (NE). These include elements such as Line Terminations (LT), Network Terminations (NT), access switches, gateways, etc. The Element Management Layer (EML) manages the physical resources and provides a common interface to the Network Management Layer (NML) for the various types of managed network elements. This layer is responsible for understanding the details of manufacturer specific information and equipment thus removing the need for this complexity of information to be held at the NML. It contains an operations system (OS) which would normally deals with functions such as configuration, fault management and performance monitoring of the physical resources which reside in the access network. The interface between the EML OS (also known as the Element Manager) and the NML OS(s) is seen as a point for standardization. Typical management functions at this level are configuration, fault management and performance monitoring. The Network Management Layer (NML) provides the functionality to bind the individual network elements into the managed network. This is the layer where the co-ordination of multiple EML OSs is undertaken to provide overall network supervision. It provides the end to end configuration of services and also provides links between different network components to form a complete network. The Service Management Layer (SML) manages the services supported by the network and is less concerned with the physical nature of the network but more with the overall function. It also provides the customer interface. Service creation, provision, cessation, billing and accounting information are some of the functions supported by this layer. The Business Management Layer (BML) is concerned with managing the complete undertaking, in accordance with the business objectives and customer requirements. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 117 Increasing Level of Abstraction Business Management Layer Service Management Layer Network Management Layer Element Management Layer BML SML NML EML NE NE NE NE NE Network Element Layer NE Figure 28: TMN Network Management Hierarchy |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 10.6.2 FSAN Management Architecture | The FSAN network management architecture is shown in detail in Annex F. The way in which this can be mapped to the satellite varies with the satellite system architecture. An important issue for satellite systems will be the protocol used for the Service Node Interface (SNI). The FSAN group assumes the use of VB5.1 or VB5.2, which are being developed within ETSI for the broadband access network interface EN 301 005 [12]. The ETSI specification is expected to be a subset of the higher level ITU-T Recommendations. The main difference between the VB5.1 and VB5.2 interfaces that is important to satellite systems is that VB5.2 supports dynamic allocation of resources in the Access Network (AN) on a connection by connection basis under the control of the SN. This enables local routing to be performed in the AN itself which is not supported in VB5.1. However, the degree of access that the SP has to this capability depends on the system architecture and commercial structure. Figure 29 shows a mapping of the FSAN management architecture to the satellite case. All user signalling is terminated at the Service Node (SN), which in turn controls the satellite access network within agreed capacity limits. The multiplexing function of the FSAN ONT is in fact distributed across the satellite network by the Access Switch functions at the gateway and the user terminal, which perform the MAC function. The FSAN management architecture defines a management service and recommended protocol implementation for each management reference point, as listed in Table 3 below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 118 OS-F OS-F OS-F OS-F OS-F SML NML NEL EML Gateway Access Switch Satellite Network Operator Domain OS-F OS-F OS-F SP Domains Access Switch Satellite(s) NT DCN if7 (IF7:X) if1 (IF1:Q3) if8 (IF8:Q3,X) if2 (IF2:Q3) if2 (IF2:Q3) if4 (IF4) if3 (IF3:SNI) if4 (IF4) if5 (IF5) if6 (IF6:UNI) Service Node Figure 29: FSAN management model applied to Satellite Access Network ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 119 Table 3: Services Provided over Management Interfaces Reference Point Management Services Comments on implementation of reference point if0 topology, service configuration and provisioning trouble/test administration account/billing/QoS performance reporting Q3 if1 configuration/provisioning/test/fault/performance management of transport resources equipment management configuration/fault/performance management of transmission system based on the TMN Q3 interface using the Common Management Interface Protocol (CMIP) Network Management Hierarchy if2 configuration/fault/performance/test management of network element network element consistency checks network element initialization/authentication/ security management SNMP initially but does not preclude migration to Q3. if3 termination of SNI management/control/maintenance/testing of interface connection establishment mapping of bearer services to access transport resources SNI if4 multiplexing of bearer services management communications connection/fault/performance management link initialization media access control security and user data encryption Management communications between OLT and ONU/ONT is via management channel over this interface. if5 error detection/reporting fault detection/reporting reset control configuration/activation/deactivation of NT resource this reference point may not be implemented if the ONU and NT are combined as in the case of the ONT if6 termination of UNI management/control/maintenance/testing of interface activation/deactivation UNI if7 ordering, service configuration and provisioning trouble/test administration account/billing/QoS performance reporting X: this interface should have special security aspects as it links 2 different domains if8 topology, ordering, service configuration and provisioning trouble/test administration account/billing/QoS performance reporting for the purposes of the service user. Q3/X: this interface should have special security aspects as it links a customer OSF to a network provider OSF. The key issues to note from the Table 3 above is that the FSAN network management architecture is predominantly based on the ITU TMN model using the Common Management Interface Protocol (CMIP) for the Q3 and X interfaces. However, it is interesting to note that the architecture also considers the availability of Simple Network Management Protocol (SNMP) interfaces for the management of network element layer equipment. With respect to the system architecture it is predicted that initially only the IF1 and some IF3 interfaces will be standardized, based on the Q3 and VB5.x interfaces respectively. However, it is desirable that interface IF2 is also standardized in the future to permit the EM OS and network elements to be procured from different suppliers. The TINA-C proposal of an open, distributed computing environment using building blocks with contract interfaces or the latest Common Object Request Broker Architecture (CORBA) could also be used as a possible framework which would lead to the adoption of a common standard for this interface. The FSAN OAM working group recommends that a consistent set of parameters are defined for each interface even if it is proprietary to allow future migration to a standard interface. The FSAN OAM group recommend that further study is needed on this and the other interfaces before any firm recommendation can be given. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 120 |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11 Standardization scenarios | This clause concludes with recommended issues for standardization. The topics are grouped into different categories. Each topic is introduced briefly, also mentioning benefits of standardization, before a suggested working method is listed. All the recommendations for standards, except one, are for Voluntary Standards. Any organization that sees benefits in having a standard can thus support it, while others who are not interested need not comply. To establish a Work Item, it is sufficient to have the support of four full ETSI members. The work items can be carried out in one or more Working Groups. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1 Services | |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.1 Service classes | Scope and Purpose: Many of the services satellite systems can provide have specific requirements for a quality of service. These can for instance relate to: • Bit-rate • Error rates • Delay • Availability, due to rain fading and other issues • Billing Not all types of service have the same set of requirements. In general, voice, audio, pictures and video can tolerate relatively high data error rates if the source coders are designed for that purpose. The actual transfer may or may not be delay sensitive. ATM-type of communication may require very low error rates. There may be variable requirements, and the dynamics of the variability may vary from service to service. ATM has a set of QoS parameters, and QoS is in general required for multimedia communication. Not all possible options may be required in all possible combinations. Recognizing that there may be an almost infinite amount of possible combinations of different sources of data in a multimedia scenario, there are sets of typical services that may be offered to the public for instance by service brokers. Satellites may set specific limitations, for instance with respect to the delay. Different satellite systems may choose different solutions that result in different characteristics. From a service providers point of view it will be beneficial to know what to expect, and within what limits satellite systems operate. A well-defined set of targets will be able to guide a system entrepreneur towards a design target. This could include recommended values for QoS subsets and variable bit-rate handling. Recommendation 1: ETSI TC SES, together with other appropriate bodies, should specify satellite specific requirements and issues relating to the different service classes for BSM systems. Working method and liaisons: Initially this work may focus on GEO satellites. The work could be done in a TC SES WG in co-operation with other ETSI bodies (SPAN, EASI, TIPHON, UMTS), ESA, DVB, TIA, IETF, ATM Forum and ITU. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 121 |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.2 Number portability | Scope and Purpose: Number portability involves the ability for users to change a service provider and keep their addressing number. For multimedia systems this will also involve IP domain addresses. The ability for a user to keep the same address encourages competition in the market. It will lower the threshold for a user to move between other access technologies and satellite access, and between different satellite systems. Satellite systems are part of the global information infrastructure. They have to offer the same capabilities as in the fixed / mobile networks. A number portability scheme for satellites should be in harmony with the GII, and satellite systems should be a natural branch on the tree of possible access methods. Recommendation 2: ETSI TC SES should define satellite specific requirements and issues to ensure that BSM systems can comply with global number portability schemes. Working method and liaisons: The work could be done in a TC SES WG in co-operation with SPAN, TC HF and EP UMTS. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.3 Global satellite addressing | Scope and Purpose: Addressing in BSM needs to be resolved. BSM systems can be used both for accessing a service provider, and for point- to-point connections. Services may include Voice over IP, Internet access, multicast and Pay TV, to mention a few. BSM terminals may be nomadic or even mobile in the future. Addressing should consider global mobility. It has to be possible to call a BSM user. Satellite specific access codes are possible, as well as country codes, service provider addresses (as in GSM). Further, addressing may be both in form of numbers and / or IP addresses. Consistency is required. Global addressing should be in harmony with other broadband access technologies. Recommendation 3: ETSI TC SES should develop satellite-specific recommendations for consistent broadband addressing and mapping between satellite end-users and IP addresses. Working method and liaisons: The work could be done in a TC SES WG in co-operation with SPAN, TC HF, TIPHON and EP UMTS. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.4 Virtual Home Environment (VHE) | Scope and Purpose: There is a definite trend towards supplying users with a Virtual Home Environment when they are roaming in other networks. VHE is a key element in UMTS. For global broadband satellite systems, relevant roaming may occur between different BSM systems, between BSM and other access technologies or even between different operators on the same satellite system. A user with a mobile or nomadic terminal may log on via different gateways world-wide. A clear trend is identified regarding fixed-mobile convergence. Therefore, a firm long-term distinction between the two should not be made. Broadband satellite systems shall be considered as a natural part of the global telecommunications infrastructure, and provide users with a familiar environment and set of services across regional borders and different technologies. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 122 Recommendation 4: ETSI TC SES should define satellite-specific issues relating to Virtual Home Environment (VHE) and define requirements needed in BSM systems to comply with global VHE. Working method and liaisons: The work could be done in a TC SES WG in co-operation with SPAN, TC HF, 3GPP and EP UMTS. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.5 System interoperability | Scope and Purpose: Intersystem interoperability across different technologies and systems is required. A BSM user should ideally be able to communicate as efficiently with broadband users on different systems as with those on his own system. Further, other users should be able to communicate as smoothly with BSM users as with terrestrial users. For instance, real-time video telephony should run equally well between users on two different BSM systems as between any other users. This may be particularly challenging when considering systems with long delay. While this could present a specific challenge, it would not be to the BSM community advantage if satellite users could not communicate as effectively with other satellite users as they could with non-satellite users. Capabilities of general services should be transparent to the satellite access technology. Satellite service providers may offer specific value added services. Inter-operability could for instance be between BSM systems and UMTS, or between ATM-based, DVB-based, IP- based and proprietary systems. Multicasting and group management may function differently on different systems, as may security, management and lawful interception. Protocol conversion can be less or more efficient. The goal of an activity on interoperability is to identify more closely the potential areas where the most performance can be gained (or at least not lost) and to define how the best possible performance can be achieved. Fixed satellite services are to be seen as part of the GII, and BSM systems will have to interact with the general core network. The interfaces to the core network will define the capabilities of BSM systems. Capabilities to offer many services, like VHE, number portability, standard billing and so on depend on this interface being adequately defined. Recommendation 5: ETSI TC SES should define requirements for efficient BSM system interoperability, at the network to network level. ETSI TC SES should also define a standard for BSM interface to the core network. Working method and liaisons: The work should be done in a TC SES WG in co-operation with TC SPAN and ITU-T SG11 (Network to Network Interoperability), EP EASI (ATM Forum), EP TIPHON (IETF), EP UMTS and TIA. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.6 System Management | Scope and Purpose: BSM systems and terminals need to be an attractive alternative for a service provider to provide broadband services through. An important aspect is a consistent management method for BSM subscribers. Consistency can be across different BSM systems, but more generally across BSM systems and other broadband access systems, such as xDSL and LMDS. There is an initiative called FSAN (Full Service Access Network) that has the support of a large number of major service providers and equipment manufacturers. Satellite systems can fit in with this initiative. FSAN characteristics: • Provides a common architecture, interface and access network management approach. • Supported by major operators. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 123 • Active initiative. • Based on the discussion in subclause 10.4, specific areas identified for study are: 1) The effects of running the VB5 RTMC and B-BCC protocols (EN 301 005 [12], EN 301 217 [14]) over a satellite access network. 2) The advantages and disadvantages to be obtained from placing ATM layer and network management intelligence/processing on board future satellite systems and the associated mappings to the ATM and FSAN approaches. For example, are there any advantages of putting connection admission control and access based signalling on board as proposed by the ATM forum or rather to maintain this functionality at the core network as proposed by the FSAN architecture. 3) The identification of which different ATM interfaces are required at the satellite-to-gateway earth station, satellite-to-satellite and satellite-to-remote terminal interfaces for different network configurations e.g. ATM interconnect or full mesh architecture and connection between public or private networks. 4) The development of TMN-based X Co-operative interfaces between satellite operators, network providers and service provides to provide seamless network and service management capabilities. Also identification of the network and service management boundaries in a broadband satellite multimedia environment, e.g. who manages the user terminal equipment. Recommendation 6: ETSI TC SES should develop a voluntary standard for BSM management, and in particular study FSAN as a candidate method. Working method and liaisons: • TC SES needs to create a liaison with FSAN, TC TMN and TC SPAN, and specifically to: • Provide satellite specific know-how. • Promote satellite access. The work could be done by a TC SES WG in co-operation with FSAN, TC TMN and TC SPAN. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.1.7 Mobile and Nomadic BSM | Scope and Purpose: • Satellite communications is a wireless communications form. There is a very significant trend towards mobile communications, and another towards an increasing use of the Internet. Both show an exponential growth, and indications are that they are correlated, as the majority of GSM users, for instance, are also Internet users. All indications are that there will be a growing and strong interest in Global Mobile Multimedia (GMM). • Satellite systems are able to provide global multimedia services, and with the right technology satellite systems can support transportable, nomadic or even mobile multimedia terminals. UMTS will be able to provide mobile multimedia services, but for high bitrate services a constant shortage of spectrum in many places is envisioned. Ku and Ka-band systems may be the satellite alternative to GMM. Given a technology to ensure correct antenna pointing according to the ETSI Ka-band harmonized standard for SIT/SUT, Ka-band systems could be mobile. The ability to support mobility is important for instance if BSM terminals are to be mounted on cars, a potentially large user group. Other broadband access schemes like cable, powerline, xDSL and also LMDS to a large degree cannot support mobility. This ability may be an important selling argument for the BSM community. • The fixed-mobile convergence supports mobility in fixed networks and vice versa. • A network topology limited to fixed terminals may not easily support mobility, and as BSM networks are now in the process of being constructed, it is also the most convenient time to take mobility and location management into account. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 124 • A future option for mobility need not necessarily be implemented during the first years or in all networks. Technology developments are needed. However, the network design can assume such developments already now. Issues may involve hand-over between other access technologies and hand-over between different service providers on the same or different satellite systems. • For nomadic and mobile terminals a location management scheme is required, so that users can be accessed globally. Location management is solved in GSM, and is also a key issue in UMTS. • Global wireless connectivity is identified as a particular strong side of BSM in phase 1. • Nomadic terminals may need roaming management. • In line with fundamental inputs, e.g. GMM. • Mobility may be a long-term issue. • Position determination is a value-added service. Recommendation 7: ETSI TC SES should develop standards for mobile BSM. Working method and liaisons: The work could be done in a TC SES WG in co-operation with EP UMTS, TC SMG and 3GPP. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.2 Reference Models | Scope and Purpose: There are several classes and variants of BSM systems. However, many show resemblance, and there is a possibility to categorize these into different classes. With respect to issues like lawful interception, standardized architectures are considered beneficial. It will also increase the possibility of developing standard equipment, both in the space domain and in the infrastructure domain, which in turn can lower the cost of the system and make BSM more competitive. Standard reference models will also be useful for management purposes. Recommendation 8: ETSI TC SES should define standard architectural reference models for different categories of BSM systems. Working method and liaisons: The work could be done in a TC SES Architecture WG, that should liaison with TC SPAN (ITU-T), FSAN, ESA, DVB and TIA. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.3 Transport mechanisms | |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.3.1 ATM over Satellite | Scope and Purpose: • Many of the planned BSM systems tend to favour ATM as a transport mechanism able to offer the required QoS for multimedia applications. Many BSM systems aim for global service, and European industry will want to be involved in the production of equipment and the delivery of services. • TIA are producing ATM/satellite standards. ETSI has not started any Satellite-ATM activity, but could consider standards approved by ATM forum or other trusted body (e.g. TIA). Global harmonization has benefits, and co-operative development with other bodies needs to be considered. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 125 • There are a numbers of issues still at the research stage, which are identified in Annex H. ATM standards for satellites are also useful when satellites are used in the core network. Recommendation 9: ETSI TC SES should define requirements for ATM over satellite, and publish a voluntary standard. Focus should be on services, interfaces and interoperability. Working method and liaisons: The work could be done in a TC SES WG in co-operation with TC SPAN, EP EASI, TIA, ATM Forum, and ITU-R. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.3.2 Internet Protocols over Satellite | Scope and Purpose: IP dominates as a multimedia protocol, and the trends indicate a move toward pure IP networks in the future. All proposed BSM systems are likely to support IP, either over DVB, over ATM or proprietary protocols. There is a large interest in IP over satellite, and several solutions to optimizing performance have been proposed, ranging from using LEO satellites, to implementing specific adaptations of the protocol (e.g. spoofing). A number of field trials with IP over satellite have been performed. • ITU-T is starting a new work area on IP matters, in co-operation with IETF. • ITU-T has major expertise on network architecture. • IETF has major expertise on protocols and are already producing satellite standards (TCPSAT). • ITU-R also studying performance requirements for IP over satellite. • TIPHON responsible for IP matters in ETSI. One of the significant issues to be resolved is the lack of compatibility of the IPSec security protocol with the spoofing techniques proposed for satellite links. Satellite IP standards can also be useful in the core network. Activities on IP must be in agreement with IETF, and TC SES cannot work on such matters in isolation. However, satellite specific knowledge can be offered, and other standardization activities can be related to satellite IP activities. Recommendation 10: ETSI TC SES should define requirements for Internet protocols (e.g. IP, TCP, UDP) over satellite, and publish appropriate voluntary standards. Focus should be on services, interfaces and interoperability. Working method and liaisons: The work could be done in a TC SES WG on IP over satellite, in co-operation with EP TIPHON, TC SPAN, IETF/TCPSAT, TIA, ITU-T, and ITU-R. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.4 Multicasting | Scope and Purpose: Multicasting is a particularly strong capability of satellite systems. Multicasting involves issues including group management, security, interoperability and air interfaces. Further issues need to be identified. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 126 Multicasting can be across different technologies, as end-users can reside on xDSL, cable modems, LMDS systems or others. This issue is therefore of particular importance to consider. However, multicasting in virtually closed networks should also be considered. Applications include local updates of company data for global organizations, e.g. spare parts for an automobile manufacturer, software updating, corporate TV, and many more. The TIA has an activity on multicasting, and as any standards will benefit from being global, co-operation is essential. • Multicasting standards must take into account developments in IP and the Internet • Existing multicast protocols are generally designed for terrestrial networks, while satellite system topologies are considerably different. • Standards could promote new applications. Recommendation 11: ETSI TC SES should work on voluntary standards for satellite multicasting. Working method and liaisons: The work could be done in a TC SES WG in co-operation with ESA, IETF and TIA, and possibly DVB. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.5 Interfaces | Current satellite communications systems in many cases use proprietary and closed standards. The satellite communications market is a very small niche market compared to the terrestrial wireless market. The terrestrial market benefits from standards such as GSM and, in the near future, UMTS. In the broadcasting field the DVB standard can be considered a success. This may be partly contributed to the capabilities of GEO satellite systems in general, but there are strong indications that having a standard has significantly helped the market. The R&TTE Directive [62] states that operators must publish their offered interfaces for the purpose of increasing competition in the terminal market. If operators and service providers refer to an ETSI standard air-interface, this would satisfy the R&TTE Directive in this respect. Having standard air-interface(s) could promote competition in the terminal market. Furthermore, when the market is shared by more than one similar system, a standard air-interface could offer security for the customers, for whom the equipment investment is independent of, and could be used with different service providers. The ability to change service providers easily is in line with the viewpoint of the European Commission (See also 8.2.6). Outside of ETSI both the DVB project and TIA are working on air interfaces for GEO systems, and ETSI will eventually publish the DVB-RCS standards. ESA has twice taken an initiative now for air interface standardization in BSM systems. The question of whether ETSI wants to be an active player or a passive observer needs to be addressed. The recommendation is that ETSI takes on a co-ordinating role, ensuring that the interfaces fit a modular and layered structure. While the DVB project would focus on broadcasting aspects, ETSI would focus on telecommunication aspects. ETSI should also ensure that ATM and IP over satellite interests are sufficiently considered. It is proposed to start an activity on the concept of a family of Radio Transmission Technologies (RTT), in the same way as has been done for UMTS/IMT2000, encompassing terrestrial and satellite system. This could be done using the methodology used for UMTS/IMT2000, which lead to a functional separation of Radio Dependent (RD) and Radio Independent (RI) functions. In any case, ETSI should consider not one single air interface, but rather a limited family, for the purpose of supporting different satellite architectures. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 127 |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.5.1 Air Interfaces for Transparent Satellites | Scope and Purpose: Transparent GEO satellites have been used over time for providing broadcast and communications services. They will play an important role also for BSM systems. The DVB project is in the process of specifying a return channel applicable for Digital Video Broadcasting. Other services may require standards, such as e.g. ATM. Recommendation 12: ETSI TC SES should develop voluntary air interface standards for transparent satellites. Working method and liaisons: ETSI should follow the DVB-RCS work for a transparent GSO satellite through the current DVB-RCS liaison. The work could be done in a TC SES WG in co-operation with TIA, ESA and DVB. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.5.2 Air Interfaces for Regenerative Satellites | Scope and Purpose: ESA/ESTEC has twice taken an initiative for defining interfaces for multimedia satellites. The first initiative was for bent-pipe satellites, while the second is for OBP satellites (subclause 6.8). Regenerative satellites (OBP) are generally intended for telecommunications purposes. TC SES should get involved, and take responsibility for the telecommunications part, which is the responsibility of ETSI to standardize in Europe. Recommendation 13: ETSI TC SES should develop voluntary air interface standards for regenerative satellite systems. Working method and liaisons: For OBP satellites, TC SES should take a more active role. ETSI currently participates in the ESA initiative as observers. The work could be done in a TC SES WG in co-operation with TIA, ESA and DVB. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.5.3 Indoor / Outdoor Unit Interface | Scope and Purpose: In the Phase-1 report [2], one of the opinions expressed by system proponents is that it would be beneficial to have a standard interface between the indoor unit and the outdoor unit. A standard interface will allow independent manufactures to compete on indoor and outdoor units. It may also allow replacement of one of the two modules only. This can be relevant for fixed terminals, e.g. if the outdoor unit can be used with different GEO BSM system, and system specific functions are kept in the indoor unit. Such an arrangement could increase competition among the service providers, and users may not need to replace the wall- or roof-mounted outdoor unit to change a satellite specific terminal, but only replace a set-top box. Recommendation 14: ETSI TC SES should develop voluntary standards for interfaces between the in-door and out-door unit for BSM terminals. The standard can include both wired and wireless options. Working method and liaisons: A TC SES WG should liaison with DVB-MHP. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 128 |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.5.4 Middleware / API | Scope and Purpose: The middleware domain and the APIs will contain many satellite specific functions. There is a need to identify and standardize these, so that application programs have a consistent set of functions and interfaces to relate to. The middleware domain shall ensure that applications work across different technologies, and as such that satellite broadband access is in harmony with other broadband access schemes. The middleware domain must be seen in relation to the rest of the network, and TC SPAN is identified as the major ETSI body to relate to. Recommendation 15: ETSI TC SES should define requirements and develop voluntary standards for middleware / API for BSM related to intelligent networks. Working method and liaisons: The work could be done in a TC SES WG in co-operation with TC SPAN and DVB-MHP. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.6 Lawful Interception | Scope and Purpose: Lawful interception possibilities will be required before an operator will be allowed to provide services in Europe. For OBP systems this is a particular challenge, both technologically and politically. The technological aspect is of interest here. With a standardized set of satellite network architecture, it may be possible to define technical standards and requirements for how to handle the LI aspect. LI is a complex and somewhat unclear issue. Exact technical requirements do not exist, but the required legal and general capabilities are basically defined. LI is the responsibility of TC SEC in ETSI. Recommendation 16: ETSI TC SES should work together with TC SEC and clarify and define requirements on LI within BSM systems. Working method and liaisons: The work could be done basically by TC SEC in co-operation with TC SES. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.7 Working Approach: Layered and modular standards | The family of BSM standards should be: 1) Layered • So that e.g. different air interfaces can be used with different management, protocols, etc. • This will allow independent updating of layers. 2) Modular • So that there can e.g. be different air interface versions. • Will allow freedom in designing new technology. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 129 The figure below illustrates the idea with a possible architecture concept. The idea borrows elements from the DVB-RCS, such as the ability of a module to have different options (i.e. for coding). Changing for instance coding or modulation should not affect compliance with other possible standards. BSM standards should depend as little as possible on the frequency band in which the system is operating. For BSM standards to become successful, it is important to recognize that there is a need for freedom in design of the payload, as otherwise the consequences for the space segment can become significant. The satellite channel, seen from a communications theoretic point of view, is much simpler for a fixed satellite service than for, e.g. the GSM system. The variations in received power, fading characteristics, etc. are larger. Limitations in the satellite domain are to a large degree technological constraints, which eventually will be challenged by new and improved technology. IP Other Browser / viewer / presenter V4 V6 UDP TCP Other Proprietary Satellite Adaption Other DVB RCS IP Sat Other ATM Sat M1 M2 Harmonized Standards EN F/TDMA [CDMA] Other QPSK QAM Figure 30: Example of how standards could be structured. The lower layer is a harmonized standard, the others are voluntary standards. At each layer different alternatives may exist, and within each alternative, different options, or modes, may exist Standards must encourage advances in technology, and be modular enough to support changes in one segment without negative consequences in another. A one-standard solution with a fixed air-interface, protocol, bit-rate, etc. is not considered a viable solution for the future. A family of BSM standards with the following characteristics could be beneficial: • Only essential requirements are mandatory. • The standards may be considered as horizontal and vertical modules. • Some, all, or none can be complied with. • Proprietary solutions can be combined with the standards. • Modules can be added later. • Modules can be removed. • Modules can be changed. • Modules can have several options. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 130 The frequency-dependent harmonized standards should be supplemented by voluntary non-frequency-dependent standards. A way to achieve this is to create modular standards. Recommendation 17: ETSI TC SES should define different categories, i.e. layers / modules, that are relevant and practical for BSM. The BSM standards that ETSI develops should fit within this structure, and allow proprietary solutions for one or more modules. Working method and liaisons: The work can be done in a TC SES WG, possibly in co-operation with the DVB project (RCS) and TIA. |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 11.8 Harmonized Standards | Scope and Purpose: The EC mandate M/284 allows ETSI to produce necessary Harmonized Standards covering the R&TTE Directive requirements. Therefore ETSI could decide within the mandate to produce Harmonized Standards for BSM. Recommendation 18: ETSI TC SES should develop harmonized R&TTE Directive standards for BSM terminals. Where required, ETSI TC SES should continue to develop harmonized standards specifying essential technical requirements for compliance with Article 3.2 of the R&TTE Directive. This process has already started, for example with the development of the Harmonized Standard EN 301 459 [17] for SIT/SUT. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 131 |
bc8dfcfc61d1bfe7cc049405984ba560 | 101 374-2 | 12 Summary Recommendations for ETSI | No. Title Recommended Liaisons 1 Service Classes TC SPAN (>ITU-T), EP TIPHON (>IETF), EP EASI (>ATM Forum), EP UMTS, ESA, DVB, TIA 2 Number Portability TC SPAN (>ITU-T), TC HF, EP UMTS 3 Global Satellite Addressing TC SPAN (>ITU-T), EP TIPHON (>IETF), TC HF, EP UMTS 4 Virtual Home Environment TC SPAN (>ITU-T), TC HF, 3GPP, EP UMTS 5 System Interoperability TC SPAN (>ITU-T SG11), EP EASI (>ATM Forum), EP TIPHON (>IETF), EP UMTS, TIA 6 System Management FSAN, TC TMN (>ATM Forum, TMF, EURESCOM), TC SPAN (>ITU- T) 7 Mobile and Nomadic BSM EP UMTS, TC SMG (> 3GPP) 8 Reference Models TC SPAN (>ITU-T), FSAN, ESA, DVB, TIA 9 ATM over Satellite TC SPAN, EP EASI (>ATM Forum), TIA, ITU-R 10 IP over Satellite EP TIPHON (>IETF/TCPSAT), TC SPAN (>ITU-T), TIA, ITU-R 11 Multicasting ESA, IETF, TIA, DVB 12 Air Interfaces for Transparent Satellites ESA, TIA, DVB 13 Air Interfaces for Regenerative Satellites ESA, TIA, DVB 14 Indoor / Outdoor Unit Interface DVB-MHP 15 Middleware / API TC SPAN (>EURESCOM), DVB-MHP 16 Lawful Interception TC SEC 17 Working Approach: Layered and modular standards DVB-RCS, TIA 18 Harmonized R&TTED standards for BSM terminals NOTE: The '>' sign means that there is liasion between the bodies. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 132 Annex A (informative): ITU-T Projects in GII NOTE 1: Previous Projects I.1 and I.2 form the basis of IP projects and have been therefore deleted from this table. NOTE 2: Study Group 2 has announced that they are not concerned with Projects A1 to A9, however the Projects are kept for the time being in the Work Programme as they are of interest for other partners as e.g. ISO/IEC/JTC 1. No. Name of Project Lead Body in ITU-T Collaborating Bodies F.1 Principles and framework for GII ITU-T SG 13 ISO/IEC JTC 1 F.2 Scenarios and key interfaces for GII ITU-T SG 13 ISO/IEC JTC 1 SG 9 (Q.24) F.3 Information appliance ITU-T SG 16 (Q.2, 11, 12, 13, 17) ITU-T SG 8 (Q.1, 3, 4), SG 9 (Q.17, 19, 20, 24, 25, 27, 28, 32) DAVIC IEC TC 100, JTC 1 F.4 End-to-end interoperability ITU-T 16 (Q.2, 3, 12, 13, 14, 15, 16, 17, 18) ITU-T SG 8 (Q.4, 6, 7, 9), SG 9 (Q.19, 24, 29) ITU-T SG 12 (Q.16, 18, 21) DAVIC IEC TC 100, JTC 1 N.1 Architecture and Layer 1 aspects of narrow-band/ broadband access infrastructures for GII ITU-T SG 15 (Q.1, 2, 3, 4) ITU-T SG 9 (Q.15, 18, 19, 20, 26) ITU-T SG 13 (Q. 11, 12, 26) DAVIC ATM Forum N.2.1 Signalling and control aspects of wideband/ broadband access interfaces for GII ITU-T SG 11 (Q.1, 6, 11) ITU-T SG 2 ITU-T SG 13 (Q.12) ITU-T SG 16 (Q.1,12) DAVIC IEEE ATM Forum ISO/IEC JTC 1 IETF N.2.2 Signalling and control aspects for wideband/ broadband network element to network element interfaces for GII ITU-T SG 11 (Q.1, 6, 11) ITU-T SG 2 ITU-T SG 13 (Q.12) DAVIC ATM Forum IETF N.3 Network interworking for the GII ITU-T SG 13 (Q.2, 8, 9 10, 27) ITU-T SG 2 (Q.2) ITU-T SG 7 (Q.1, 6, 8, 9) ITU-T SG 10 (Q.6, 7) ITU-T SG 12 (Q.16, 18, 21) ISO/IEC JTC 1 ATM Forum Frame Relay Forum N.5.1 "Intelligent Mobility" for the GII, IMT-2000 (former FPLMTS) ITU-T SG 11 (Q.7, 8, 11, 13) ITU-R (TG 8) ITU-T SG 2 (Q.13), SG 10 ITU-T SG 13 (Q.1, 23, 27, 29) N.5.2 "Intelligent Mobility" for the GII, Global Mobility ITU-T SG 13 (Q.1, 23, 27, 29) ITU-R (TG 8) ITU-T SG 10, SG 11 (Q.5, 7) N.6 Harmonization of B-ISDN Signalling Protocols and their interfaces to public Broadband Networks ITU-T 11 (Q.11) ITU-T SG 13 (Q.8) ATM Forum ISO/IEC JTC 1 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 133 No. Name of Project Lead Body in ITU-T Collaborating Bodies N.7 Enhanced network intelligence for the GII ITU-T SG 11 (Q.5) [IN], ITU-T SG 4 (Q.13-17, 19-20) [TMN], ITU-T SG 4 (Q.21) [IN information model] ITU-T SG 13 (Q. 23, 29) N.8 Quality of Service and network performance ITU-T SG 13 (Q.13, 14, 15, 16, 17) ITU-T SG 2 (Q.3, 6, 8) ITU-T SG 9, ITU-T SG 12 (Q.16, 18, 21), ITU-T SG 7 (Q.2) ATM Forum IETF N.9 Addressing for the GII ITU-T SG 2 (Q.1) ITU-T SG 7 (Q.3, 21) ITU-T SG 13 (Q.2) ISO/IEC JTC 1 ATM Forum IETF N.10 Conditional access methods ITU-T SG 9 N.11 Interactive Television and sound programming ITU-T SG 9 M.1 Network-oriented middleware and network operating systems for GII ITU-T SG 13 (Q.3, 29) [initially] ITU-T SG 10 (Q.1, 3) IETF ATM Forum DAVIC OMG Others M.2 APIs harmonized with network capabilities ITU-T SG 8 (Q.8, 9) ATM Forum ITU-T SG 16 (Q.2) M.3 Technical framework for electronic commerce ITU-T SG 16 ISO/IEC SC 18, 30, TINA-C M.4 Middleware for multimedia ITU-T SG 16 (Q.16,17) ITU-T SG 7 (Q.24) SG 10, OMG, TINA-C, DAVIC, Open Group M.5.1 Service, Network and System Management for GII (TMN) ITU-T SG 4 (Q.13-21) Network Management Forum M.5.2 Service, Network and System Management for GII (Open Distributed Management) ITU-T SG 4(Q.14) M.6.1 Security (end-to-end) ITU-T SG 7 (Q.20) ITU-T SG 11 (Q.3), IETF M.6.2 Network Security M.7 High-level naming ITU-T SG 7 (Q.15, 17, 21) IETF M.8 Object-oriented environments ITU-T SG 10 (Q.7) M.9 Advanced HCIs for telecommunications management ITU-T SG 10 (Q.3) SGs 2, 4 M.10 Software architectures for advanced HCIs ITU-T SG 10 (Q.3) t.b.d. M.11 Network capabilities for charging and billing in GII ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 134 A.1 Medical informatics ITU-T SG 2 t.b.d. A.2 Libraries ITU-T SG 2 t.b.d. A.3 Electronic museums ITU-T SG 2 t.b.d. A.4 Road transport informatics ITU-T SG 2 t.b.d. A.5 Electronic purse ITU-T SG 2 t.b.d. A.6 Industrial multimedia communication ITU-T SG 2 t.b.d. A.7 Ergonomics ITU-T SG 2 t.b.d. A.8 Character set ITU-T SG 2 t.b.d. A.9 Geographic information systems ITU-T SG 2 t.b.d. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 135 Annex B (informative): ITU-T IP Project Work Areas Area 1 - Integrated architecture The advent of IP networks and their integration into telecommunications networks, including both fixed and mobile networks, provides substantial new thinking for the evolution of both networks. For example, the separation of service provision from transport, a key element in IN development and in Internet applications, changes much of the basic telecommunications architecture. Also, control systems, which in telecommunications networks have evolved to outband SS7 and ISDN signalling systems as opposed to inband approaches in an IP based network, provide opportunities for new developments. One example under consideration is to use an IP overlay as a control structure for both telecommunications and Internet type networks. The future of the IP protocol also requires analysis. With new approaches for integrating connectionless services with traditional telecommunications services and with new applications and business coming into use, it is likely that a new IP protocol, meeting all the new needs, including additional control requirements will be developed. The architectural implications of this have yet to be determined. The initial focus is to identify the new network concepts and to propose architectural approaches that meet the challenging future needs of data, video and voice as well as multi-media applications. Area 2 - Impact on telecommunications access infrastructures of access to IP applications The key objective is to identify the key access network interface requirements and access configurations to provide an effective gateway from telecommunications access networks and telecommunications access components to IP networks (including both wired and wireless accesses). The project will address the issues (including interfaces, protocols, network management, etc.) related to access to IP applications via an IP based network Points of Presence (POPs), using the various access networks and technologies. Some access networks, such as cable TV networks and broadcast satellites, were only designed to broadcast signals to the home, not to carry data back towards the core network. One-way access systems have to be enhanced to two-way capability or used in combination with other techniques (e.g. upstream modem/phone line configurations) to support bi- directional communication, for example, in client-server applications. In addition, problems related to traffic management in the case of switched access to Internet over PSTN/ISDN may require the development of dedicated functions and interfaces on voice switches to re-route data traffic on dedicated Points-of-Presence as close as possible to the source. The initial focus will be on terminal interfaces from PSTN and ISDN (e.g. ADSL) and on access network interfaces (e.g. V interfaces) to determine changes necessary to accommodate additional requirements for access to IP based applications. Area 3 - Interworking between IP based network and switched-circuit networks, including wireless based networks The primary objective is to identify and analyse potential network configurations and network interface requirements (for both fixed and mobile networks) to ensure mutually effective IP and telecommunications network support to the burgeoning business requirements encompassing both technologies. Concerning network interworking the area will address interworking (including network management capabilities) between IP-based networks (Intranets, the Internet, etc.) and a number of typical core networks. The project will also consider related issues, such as traffic management. For example networks supporting Internet traffic have different traffic characteristic from telephony and solutions must be developed to ensure efficient management of processing power, network capacity and memory resources. The initial focus is the identification and analysis of alternative inter- related architectures to determine the key interface requirements between IP network and telecommunications network components. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 136 The project will also include study of the various voice over IP scenarios and the support of the integration of PSTN services (e.g., a telephone call) with those offered by an IP based network through the World Wide Web. Examples of such services are Click-to-Dial, Click-to-Fax, and Voice access to content. The initial focus is on identification and preliminary definition of interactive services for which functional and architectural requirements will be determined for input to the Access and Interworking considerations. Area 4 - Multimedia applications over IP There is a growing market for real-time multimedia communication over IP-based networks and for extending this over the PSTN/ISDN. The objective of this project is to support this market through the coordination of ITU-T activities, and ensure inter-operation for a variety of scenarios. The initial benchmark service to be supported in this area of the project is interworking between voice over IP-based networks and PSTN/ISDN. This area of the project will address a number of issues, including: • requirements for interoperability between IP networks and PSTN/ISDN; • service definitions; • requirements for service interoperability; • reference configurations and functional models; • multimedia coding; • call control procedures, information flows and protocols; • numbering and addressing; • charging/billing; • security; • end-to-end quality of service aspects, including transcoding and echo-cancellation. Area 5 - Naming, Numbering, Addressing and Routing The increasing demand to extend the capabilities afforded by provision of an IP based telecommunications infrastructure which provides the flexibility and capacity required to satisfy the growing international multimedia needs has resulted in urgent commercial necessity to enable interworking with conventional telecommunication networks e.g. PSTN/ISDN and PSPDN. Initially the key issues to be addressed under this area are: • Numbering, and Addressing to provide international access to users who are IP based initially for the purpose of VoIP; • The operational requirements to route international correspondence traffic to IP based networks and user interfaces; and • The service interworking for the provision of international public correspondence including evolving multimedia applications. Area 6 - Transport for IP-structured signals Currently IP traffic is transported largely over telecommunications facilities, using telecommunications channels to support IP protocols and applications. Depending on the tariffs and other cost considerations, IP network traffic is moving to dedicated transport, independent of the telecommunications networks. If this trend continues, the Internet could eventually overlay the telephone network, removing much of the data traffic from telecommunications networks, causing severe decline in telecommunications business. On the other hand it is axiomatic that joint use of networks for voice and data provides more efficient use of precious resources. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 137 The focus of this part of the project deals with evolutionary aspects of the transport used for IP-based networks. This includes the optimization for the direct transport of IP traffic over Synchronous Digital Hierarchy (SDH) and optical infrastructures. One example is their possible evolution towards integration with ATM Networks. ATM has become the chosen technology for the B-ISDN within traditional telecommunication networks. As such it is ideally suited to fulfil the needs of large multi-function networks requiring high-speed connections in the backbone and access segments. In addition, ATM provides defined quality of service parameters, in contrast to the current "best effort" of the Internet. Thus ATM can support the foreseen evolution towards a highly reliable and highly available Internet, with defined qualities of service. ATM may also make use of SDH and optical network infrastructures. The objective of this section of the project is to determine approaches to share network resources to the mutual benefit of both IP and telecommunications networks, and their users. Area 7 - Signalling support, IN and routing for services on IP-based networks This area of the project will address at least the following topics: • Efficiently identifying and routing traffic destined for Internet Service Providers (ISPs) to minimize negative impact upon the Public Switched Telephone Network (PSTN), which has been engineered for relatively short holding time calls; • defining signaling support for new, value added services which may enable public network operators, as well as ISPs, to capitalize on the growing demand for Internet based and Intelligent Network (IN) based capabilities; • serving the need of ISPs, Internet Access Providers, and "Internet users" to flexibly manage dynamic bandwidth and quality of service demands from a public network; • defining mobile wireless access to services over an IP based network, e.g., virtual private networks, provided by either ISPs or public network operators; and • signaling support for Service Interworking of both dial-up Internet access data applications and Voice over IP applications with traditional telecommunication services, including support of signaling applications and user parts over IP based networks. Area 8 - Performance Performance Recommendations for IP-based networks and services, interpreted broadly to include IP based networks and affiliated technologies (e.g., World Wide Web) are being developed by a number of Study Groups. The planned work will: • Build upon and specialize ongoing GII performance studies. • Apply and revise the existing ITU-T Recommendations that establish performance and quality requirements for end-user services in light of the unique performance issues of IP-based networks and services. • Develop new performance-related ITU-T Recommendations (i.e., define performance parameters and objectives) for IP-based networks and services. • As necessary, revise or develop ITU-T Recommendations addressing the performance of the lower layer networking ("layer 2 networking") to support the transport of IP networking ("layer 3 networking"), e.g., timing and synchronization issues as they relate to IP-based networks and services. • Address a broad range of performance issues, including IP-network interworking with and integration with other telecommunications services and networks (e.g., public switched telephone network, Integrated Services Digital Networks, radio/mobile telecommunications networks, broadcast/cable networks, SDH, ATM, frame relay). The initial focus is on the definition of quantitative quality-of-service (QoS) commitments applicable to well-defined IP-based services and meeting performance needs of end-users for real-time IP-based services (e.g., telephony, multimedia) while continuing to support conventional best-effort IP communication services. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 138 Areas 9, 11 and 12 - Management of mixed telecom and IP-based environments The objectives of these areas are two-fold: • To address the evolution of TMN Recommendations to support the integrated remote management of mixed environments as well as management of their constituent parts; and • To address the management of mixed environments not covered by the evolution of TMN Recommendations. Integrated remote management is expected to be essential to gain the full benefits of integrating IP with traditional telecom technologies. Currently management of IP-based networks is focused on the use of IETF management standards while the management of traditional telecom networks is supported by ITU-T TMN Recommendations. However there is a need to understand the management needs of both domains in order to develop an integrated perspective. It is expected that as the distinction between these two network domains blurs, the convergence of their management approaches will naturally follow. During this convergence period and in part to ensure its success, integrated remote management will be needed and will focus on the creation of an integrated set of management architecture, requirements, information, and protocols. It expected that a similar philosophy will drive the creation of ITU-T management specifications outside of the realm of TMN. Area 10 - Security aspects There are many interworking scenarios with existing telecommunication networks and IP-based networks. Due to the fact that the structure of the IP-based networks and the associated security aspects are completely different to those of telecommunication networks, the security aspects have to be analysed in relation with interworking between telecommunication and IP-based networks. Requirements have to be developed for these scenarios, especially for: • A voice call from an IP terminal connected to an IP-based network to a GSTN phone; • A voice call from a GSTN phone to an IP terminal connected to an IP-based network; • A voice call from a GSTN phone to another GSTN phone via an IP network; • A voice call from an IP terminal connected to an IP-based network to another IP terminal connected to an IP- based network via the GSTN. When the word "security" is used without qualification there are usually many interpretations of the term. Hence it is useful to provide a taxonomy of security-related issues so that a common understanding can be more quickly reached. Within a telecommunications context there are four roles, each with a different set of security related concerns. These are the user, network operator, third party and government. These roles are not mutually exclusive and any given individual or organization may assume two or more of the roles. For example, a third party is inevitably also a user, and a network operator may assume a government role. There are ranges of security concerns. Some are of interest to a single role, and some to several. These include end-to- end privacy of data, user identification, anonymous access, access control intrusion detection, non-repudiation and lawful intercept. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 139 Annex C (informative): ITU-R SG4 Questions Under Study FIXED-SATELLITE SERVICE, (reference ITU-R Radiocommunication Study Group 4) Question ITU-R No. Title Category Page number 7-3/4 Baseband transmission variability, delay and echoes in systems in the fixed-satellite service S2 7 32-3/4 Methods for determining the interference potential of earth stations in the fixed- satellite service in the frequency bands shared with radio-relay systems S2 8 42-1/4 Characteristics of antennas at earth stations in the fixed-satellite service S1 9 44-1/4 Use of transportable transmitting earth stations in the fixed-satellite service including use for feeder links to broadcasting satellites S2 10 46-2/4 Preferred multiple-access characteristics in the fixed-satellite service S2 11 55-2/4 Feeder links in the fixed-satellite service used for the connections to and from geostationary satellites in various mobile-satellite services S1 12 56-1/4 Frequency sharing between the inter-satellite service when used for links of the fixed-satellite service and terrestrial radiocommunication services S2 14 57-1/4 Preferred technical characteristics and selection of sites for earth stations in the fixed-satellite service to facilitate sharing with terrestrial services S2 15 60-1/4 Sharing criteria for protecting systems in the fixed-satellite service against interference from line-of-sight radio-relay transmitters operating in shared frequency bands S2 16 61/4 Criteria for frequency sharing between the fixed service and the fixed-satellite service in bidirectionally allocated frequency bands S3 17 62/4 Frequency sharing of the fixed-satellite service and the inter-satellite service with the fixed service under provisions of RR Article 14 S2 18 63-1/4 Frequency sharing of the fixed-satellite service with terrestrial radio services other than the fixed service under the provisions of Article 14 of the Radio Regulations S3 20 67-1/4 Frequency sharing between the fixed-satellite service and the Earth exploration- satellite (passive) and space research (passive) services near 19 GHz C1 22 68-1/4 Frequency sharing of the fixed-satellite service and the inter-satellite service with other space radio services under provisions of Article 14 of the Radio Regulations S2 23 70-1/4 Protection of the geostationary-satellite orbit against unacceptable interference from transmitting earth stations in the fixed-satellite service at frequencies above 15 GHz S2 25 73-1/4 Availability and interruptions to traffic on digital paths or circuits in the fixed-satellite service S2 27 75-3/4 Performance objectives of international digital transmission links in the fixed-satellite service S1 28 76-1/4 Voice and data signal processing for international digital transmission links in the fixed-satellite service S2 29 77-1/4 Video signal processing for international digital transmission links in the fixed- satellite service S2 30 78-1/4 Use of satellite communication systems in the B-ISDN S2 31 81-1/4 Frequency sharing among networks in the fixed-satellite service, the mobile-satellite service and those of satellites equipped to operate in more than one service in the 20 - 50 GHz band S2 32 201-1/4 Digital satellite systems in the FSS in synchronous transport networks based on the SDH S1 34 202-1/4 Interference criteria in the fixed-satellite service for the optimum inhomogeneous use of the available capacity of the geostationary orbit S1 36 203-1/4 The impact of using small antennas on the efficient use of the geostationary-satellite orbit S1 38 204/4 Interference of undetermined origin on Earth-to-satellite links S2 39 205-1/4 Frequency sharing between non-geostationary satellite feeder links in the fixed-satellite service used by the mobile-satellite service S1 40 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 140 Question ITU-R No. Title Category Page number 206-2/4 Sharing between non-geostationary satellite feeder links in the fixed-satellite service used by the mobile-satellite service and other space services, and networks of the fixed-satellite service using geostationary satellites S1 41 208/4 Use of statistical and stochastic methods in evaluation of interference between satellite networks in the fixed-satellite service S2 43 209/4 The use of frequency bands allocated to the fixed-satellite service for both the up and down links of geostationary-satellite systems S2 45 214/4 Technical implications of steerable and reconfigurable satellite beams S1 46 216/4 Interruptions to traffic due to site diversity arrangements and/or equipment protection arrangements on digital paths or circuits in the fixed-satellite service S2 47 218-1/4 Compatibility between on-board processing satellites in the FSS and terrestrial networks S2 49 219/4 Protection of non-geostationary satellite feeder links in the fixed-satellite service used by the mobile-satellite service from radio-relay systems in the shared frequency bands S2 51 220/4 Interference criteria for systems in the fixed-satellite service using spread spectrum multiple access S2 52 221/4 Selection of radio stars visible in southern hemisphere for use in determining G/T values for antennas in the fixed-satellite service S2 53 222/4 Protection ratio masks for TV/FM carriers S1 54 223/4 Interference criteria for short-term interference events into the fixed-satellite service networks S1 55 224/4 Technical coordination and optimization methods for systems in the fixed-satellite service to be used under Appendix 30B of the Radio Regulations S1 57 226-1/4 Use of portable and transportable transmitting earth stations for digital transmission of digital high-definition television for news gathering and outside broadcasts via satellite S1 59 227/4 Use of digital transmission techniques for satellite news gathering (sound) S2 61 230/4 Studies on efficient use of FSS orbit/spectrum resources resulting from Resolution 18 (Kyoto-94) C1 62 231/4 Sharing between networks of the fixed-satellite service using non-geostationary satellites and other networks of the fixed-satellite service S1 64 232/4 Use of regenerative processing in FSS allocations S2 65 233/4 Dedicated user digital satellite communications systems and their associated architectures S2 66 234/4 Phase jitter and wander requirements for satellite earth station modems S1 68 235/4 Use of operational facilities to meet power-flux-density limitation under Article 28 of the Radio Regulations S1 69 236/4 Interference criteria and calculation methods for the fixed-satellite service S1 70 237-1/4 Sharing criteria for systems in the fixed-satellite service involving a large number of non-geostationary satellites with radio-relay systems in the 18,8 to 19,3 GHz and 28,6 to 29,1 GHz bands S1 72 238/4 Sharing criteria for intersatellite links between non-geostationary satellites in connection with feeder links for the mobile-satellite service using the same frequency bands with radio-relay systems S2 73 239/4 Sharing criteria between systems utilizing inter-satellite links C1 75 240/4 Technical implications of possible definition of the quasi-geostationary orbit on the fixed-satellite service sharing frequency bands with the fixed service C1 76 241/4 Technical implications of possible definition of the quasi-geostationary orbit on the fixed-satellite service using geostationary and non-geostationary orbits C1 77 242/4 Sharing between feeder links for the mobile-satellite service and the aeronautical radionavigation service in the space-to-Earth direction in the band 15,4 - 15,7 GHz and the protection of the radioastronomy service in the band 15,35 - 15,4 GHz C1 78 243-1/4 Sharing between feeder links for the mobile-satellite service and the aeronautical radionavigation service in the Earth-to-space direction in the band 15,45 - 15,65 GHz C1 80 244/4 Sharing between feeder links of the mobile-satellite (non-geostationary) service in the band 5 091 - 5 250 MHz and the aeronautical radionavigation service in the band 5 000 - 5 250 MHz C2 82 245/4 Out-of-band and spurious emission limits C1 84 246/4 Sharing between the inter-satellite service, Earth-exploration satellite (passive) service and other services in frequency bands above 50 GHz C1 85 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 141 Question ITU-R No. Title Category Page number 247/4 Design objectives for radiation patterns applicable to non-geostationary-satellite orbit/mobile-satellite service feeder link Earth stations operating in the 5/7 GHz band S1 86 248/4 Frequency sharing between systems in the fixed-satellite service and wireless digital networks around 5 GHz S1 87 249/4 Interoperability of equipment for digital transmission of television news gathering via satellite news gathering (SNG) S1 88 250/4 Feasibility of the fixed-satellite service sharing with the fixed service operating on the same frequencies in the range 30 - 52 GHz S1 89 251/4 Sharing criteria for systems in the fixed-satellite service using the same frequency bands with stratospheric high density systems in the fixed service S1 91 252/4 Criteria for the protection of Appendix 30B Plan against intereference from NGSO systems S1 93 253/4 Determination of coordination area for Earth stations operating with non- geostationary satellites in the fixed-satellite service in the frequency bands shared with the fixed service S1 94 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 142 Annex D (informative): IETF Working Group Areas D.1 Applications Area Working Groups • Application Configuration Access Protocol (acap). • Calendaring and Scheduling (calsch). • Common Name Resolution Protocol (cnrp). • Content Negotiation (conneg). • DAV Searching and Locating (dasl). • Detailed Revision/Update of Message Standards (drums). • Electronic Data Interchange-Internet Integration (ediint). • Extensions to FTP (ftpext). • HyperText Transfer Protocol (http). • Instant Messaging and Presence Protocol (impp). • Internet Fax (fax). • Internet Open Trading Protocol (trade). • Internet Printing Protocol (ipp). • LDAP Duplication/Replication/Update Protocols (ldup). • LDAP Extension (ldapext). • Large Scale Multicast Applications (lsma). • Mail and Directory Management (madman). • Message Tracking Protocol (msgtrk). • NNTP Extensions (nntpext). • Printer MIB (printmib). • Schema Registration (schema). • Telnet TN3270 Enhancements (tn3270e). • Uniform Resource Locator Registration Procedures (urlreg). • Uniform Resource Names (urn). • Usenet Article Standard Update (usefor). • WWW Distributed Authoring and Versioning (webdav). • Web Replication and Caching (wrec). • Web Versioning and Configuration Management (deltav). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 143 D.2 General Area Working Group • Process for Organization of Internet Standards ONg (poisson). D.3 Internet Area Working Groups • AToM MIB (atommib). • DNS IXFR, Notification, and Dynamic Update (dnsind). • Dynamic Host Configuration (dhc). • Frame Relay Service MIB (frnetmib). • IP Over Fibre Channel (ipfc). • IP Over IEEE 1394 [66] (ip1394). • IP over Cable Data Network (ipcdn). • IP over VBI (ipvbi). • IPNG (ipngwg). • Interfaces MIB (ifmib). • Internetworking Over NBMA (ion). • Point-to-Point Protocol Extensions (pppext). • Service Location Protocol (svrloc). • Zero Configuration Networking (zeroconf). D.4 Operations and Management Area Working Groups • ADSL MIB (adslmib). • Authentication, Authorization and Accounting (aaa). • Benchmarking Methodology (bmwg). • Bridge MIB (bridge). • Distributed Management (disman). • Domain Name Server Operations (dnsop). • Entity MIB (entmib). • Ethernet Interfaces and Hub MIB (hubmib). • G and R for Security Incident Processing (grip). • MBONE Deployment (mboned). • Network Access Server Requirements (nasreq). • Next Generation Transition (ngtrans). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 144 • Physical Topology MIB (ptopomib). • Policy Framework (policy). • Remote Authentication Dial-In User Service (radius). • Remote Network Monitoring (rmonmib). • Roaming Operations (roamops). • Routing Policy System (rps). • SNMP Agent Extensibility (agentx). • SNMP Version 3 (snmpv3). • The Internet and the Millennium Problem (2000). D.5 Routing Area Working Group • Border Gateway Multicast Protocol (bgmp). • Data Link Switching MIB (dlswmib). • General Switch Management Protocol (gsmp). • IP Routing for Wireless/Mobile Hosts (mobileip). • IS-IS for IP Internets (isis). • Inter-Domain Multicast Routing (idmr). • Inter-Domain Routing (idr). • Mobile Ad-hoc Networks (manet). • Multicast Extensions to OSPF (mospf). • Multicast Source Discovery Protocol (msdp). • Multiprotocol Label Switching (mpls). • Open Shortest Path First IGP (ospf). • Protocol Independent Multicast (pim). • Routing Information Protocol (rip). • SNA DLC Services MIB (snadlc). • UniDirectional Link Routing (udlr). • Virtual Router Redundancy Protocol (vrrp). D.6 Security Area Working Groups • An Open Specification for Pretty Good Privacy (openpgp). • Authenticated Firewall Traversal (aft). • Common Authentication Technology (cat). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 145 • Domain Name System Security (dnssec). • IP Security Protocol (ipsec). • Intrusion Detection Exchange Format (idwg). • One Time Password Authentication (otp). • Public-Key Infrastructure (ITU-T Recommendation X.509 [74]) (pkix). • S/MIME Mail Security (smime). • Secure Network Time Protocol (stime). • Secure Shell (secsh). • Simple Public Key Infrastructure (spki). • Transport Layer Security (tls). • Web Transaction Security (wts). • XML Digital Signatures (xmldsig). D.7 Transport Area Working Groups • Audio/Video Transport (avt). • Differentiated Services (diffserv). • IP Performance Metrics (ippm). • IP Telephony (iptel). • Integrated Services (intserv). • Integrated Services over Specific Link Layers (issll). • Media Gateway Control (megaco). • Multicast-Address Allocation (malloc). • Multiparty Multimedia Session Control (mmusic). • Network Address Translators (nat). • Network File System Version 4 (nfsv4). • ONC Remote Procedure Call (oncrpc). • PSTN and Internet Internetworking (pint). • Performance Implications of Link Characteristics (pilc). • Realtime Traffic Flow Measurement (rtfm). • Reliable Multicast Transport (rmt). • Resource Allocation Protocol (rap). • Resource Reservation Setup Protocol (rsvp). • Session Initiation Protocol (sip). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 146 • Signaling Transport (sigtran). • TCP Implementation (tcpimpl). • TCP Over Satellite (tcpsat). D.8 User Services Area Working Groups • FYI Updates (fyiup). • Responsible Use of the Network (run). • User Services (uswg). • Web Elucidation of Internet-Related Developments (weird). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 147 Annex E (informative): ATM Forum Work Areas Current Items as of August 1999 Control Signalling Network Call Correlation Identifier Work in Progress 12/99 GFR Signalling Work in Progress 12/99 Call Rerouting Work in Progress 12/99 BICI v2.2 Work in Progress 12/99 DiffServ Signalling Work in Progress 12/99 Connection Modify Work in Progress 12/99 Path and Correction Trace Work in Progress 12/99 Joint CS and RA MPOA Addendum for Frame Relay Links Work in Progress 5/00 MPOA v1.1 Addendum for VPN Support Final Ballot 9/99 MPOA v1.1 Addendum for QoS Work in Progress 5/00 Lan Emulation/ MPOA Carrier Interface (M5) Requirements and CMIP MIB Work in Progress 7/00 Usage Measurement Requirements and Logical MIB Work in Progress 12/99 CORBA Work In Progress 7/00 Network Management Chair: Roger Kosak Customer/Sevice Provider Interface M3 Work in Progress 7/00 PHY Control Final Ballot 11/99 Fractional Nx64 on E1/T1 Final Ballot 11/99 2,4 Gbps SONET PHY Final Ballot 11/99 Utopia Level 3 (2,4 Gbps) Straw Ballot 2/00 Utopia Level 4 (10 Gbps) Work in Progress TBD 1,0 Gbit Cell Based PHY Work in Progress TBD Frame Based ATM/PHY Interface Work in Progress TBD Device Control Protocol Work in Progress TBD 10 Gbps SONET Interface Work in Progress TBD Physical Layer Chair: John Mick Multiplexed Status Polling for UL3 Work in Progress TBD ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 148 Current Items as of August 1999 Control Signalling RBB (Residential Broadband) Bi-Level Addressing Work in Progress TBD PNNI 1.0 Addendum - Secure PNNI Routing Work in Progress TBD Routing and Addressing PAR Addendum: Interoperability with ILMI-based Server Discovery Work in Progress TBD Security Specification Version 1.1 Work In Progress 2/00 Secure User Registration Work In Progress TBD Security Chair: Richard Graveman Java API Work in Progress 9/99 Frame Based ATM over Sonet/SDH Work in Progress TBD ATM Name Server v.2 Work in Progress 9/99 Frame Based ATM over Ethernet Work in Progress 2/00 Service Aspects and Applications Chair: Bahman Mobasser Frame Based ATM over Blue Tooth Work in Progress TBD Conformance Abstract Test Suite for Signalling (UNI 3.1 [37]) for the User Side Work in Progress 11/99 Performance Testing Specification Final Ballot 9/99 Conformance Abstract Test Suite for LANE 1.0 Server Inactive TBD Conformance Abstract Test Suite for UNI 3.0/3.1 ILMI Registration (User Side and Network Side) Inactive TBD UNI Signalling Performance Test Suite Work in Progress TBD Interoperability Test Suite for LANE v1.0 Inactive TBD Introduction to ATM Forum Test Specification v2.0 Work in Progress 11/99 Conformance Abstract Test Suite for SSCOP v1.1 Final Ballot 4/99 PICS Style Guide Straw Ballot 11/99 Conformance Abstract Test Suite for ABR Straw Ballot 11/99 PNNI Signalling Abstract Test Suite Work in Progress TBD Testing Conformance Abstract Test Suite for Signalling (UNI 3.1 [37]) for the Network side v2.0 Final Ballot 9/99 Addendum to TM4.1 Supporting IP Differentiated Services and IEEE 802.10 Work in Progress 2/00 Traffic Management Chair: Tim Dwight Addendum to TM4.1 Supporting Specification of a MCR for UBR Work in Progress 2/00 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 149 Current Items as of August 1999 Control Signalling Voice and Telephony over ATM Chair: Don Choi Local Loop Emulation using AAL2 Work in Progress 12/99 WATM Spec 1.0 Straw Ballot 11/99 Wireless ATM WATM Wireless Interworking Straw Ballot 4/00 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 150 Annex F (informative): Full Service Access Network (FSAN) F.1 Introduction In 1995 a group of telecommunication network operators and equipment suppliers established an international three year initiative to create the conditions for the development and introduction of access systems supporting a full range of narrow-band and broadband services. This activity was achieved through six working groups responsible for the following areas: • Systems Engineering and Architecture; • Optical Access Networks; • Home Networks and Network Termination; • Operation Administration and Maintenance; • VDSL; • Component Technology. After three years of successful collaborative development a common requirement specification was issued in June 99 for FSAN architectures. The FSAN goals have not been to produce new standards but to build on the resources available from the ATM Forum, ITU and ETSI standards, e.g. the FSAN approach follows the principles stated in ITU-T Recommendation G.902 [24] for generic access networks. This clause reviews the synergy between the current standards for broadband terrestrial access networks and the proposals for the future Broadband Satellite Multimedia (BSM) systems. The objective is to identify areas where ETSI work on BSM system standards could be based on existing recognized and adopted terrestrial access network standards. An overview of the various network architectures and management approaches adopted by industry groups such as the FSAN consortium, the ATM Forum and DAVIC is provided and relationships with ITU and ETSI standards are identified. FSAN is covered in the most detail because it provides a common architecture, interface and network management approach for access networks, which could be applied to the BSM case. Areas of synergy and conflict are discussed and a possible way forward for ETSI BSM standards work is proposed. F.2 FSAN F.2.1 Architecture The generic FSAN architecture is shown in Figure F.1 below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 151 SN Extended Feeder OLT ODN ONU NT ONT Access Network SNI User UNI Figure F.1: Generic FSAN Architecture The key components in the generic FSAN architecture are: • The Service Node (SN), which is the network element that provides access to the various switched and or permanent telecommunications services. For switched services the SN provides call control, connection control and resource handling functions. • The Access Network (AN) which refers to the equipment used to provide the transport capability for the provision of telecommunication services between a Service Node Interface (SNI) and one more associated User Network Interfaces (UNI). User signalling is carried transparently by the AN. • The Extender Feeder which can be used to provide the physical resources to extend the AN over larger distances. • The Optical Line Termination (OLT) which provides the network side interface of the AN. An OLT can be connected to more than one ODN. • The Optical Distribution Network (ODN) refers to the point to multipoint fibre network used to transport services in a common format from the OLT to the ONU/ONT. The ODN may consist of Passive Optical Networks (PONs). • The Optical Network Unit/Termination (ONU/ONT) provides the customer side-interface of the AN. It is connected to the ODN. For some operators the ONU and NT functions will be combined into one physical resource referred to as an ONT. • The Network Termination (NT) is the physical resource which resides in the customer premises and forms the boundary of the AN. This interface is referred to as the User Network Interface (UNI). The NT provides the onward transmission of services over building wiring to Customer Premise Equipment (CPE). The FSAN architecture is based on the delivery of Asynchronous Transfer Mode (ATM) narrow-band and broadband services using a selection of drop medium to take the required services from the remote node to the customer termination unit. The key drop modes being a combination of fibre and copper Asymmetrical Digital Subscriber Line (ADSL) and Very high speed Digital Subscriber Line (VDSL) for Fibre to the Exchange, Kerb and Cabin. Whilst the user of fibre optic only networks for fibre to the home networks. This principle is shown schematically in the figure below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 152 The Common Access System ATM OLT ONU Switch Node PON Head End Node Local Exchange Cabinet NTE ATM OLT ONU NTE ATM OLT ONU NTE ATM OLT ONU NTE SDH PON ADSL VDSL VDSL UNI FTTCab FTTK/ FTTB FTTB/ FTTH FTTEx VB5 Home Kerb Figure F.2: FSAN Delivery Architectures F.2.2 SNI and UNI architectures The FSAN Common Technical Specification specifies the use of V interfaces at the digital SNI for the support of broadband or combined narrow-band and broadband access networks. There are two types of VB interfaces VB5.1 and VB5.2 both standardized within the ITU and ETSI. The functionality of the VB5.1 interface is to: • Define the access type, ATM multiplexing and cross-connectivity in the AN at the Virtual Path (VP) and Virtual Connection (VC) level. This includes the allocation of VPs and VCs. This is required to provide the multiplexed and demultiplexed streams from the UNI to the SNI and vice-versa. VB5.1 supports the use of the ATM layer for user plane, control plane and management plane links. • Define the time critical management functions and real time co-ordination between the AN and the SN. This is achieved through a Real Time Management plane Co-ordination (RTMC) protocol. • Definition of the timing and Operation Administration and Maintenance (OAM) flows between the AN and the SN. This functionality is shown in figure 3. The Ia interface is the VB5.1 interface point adjacent to the AN equipment and the Ib interface is the VB5.1 interface point adjacent to the SN equipment. AN SN Ia Ib VP & VC Links VB5.1 RTMC TIMING OAM Figure F.3: VB5.1 Functions The following key issues should also be noted: • In VB5.1 the AN passes on transparently any user signalling and charging information directly to the SN. • All call control and associated connection control resides in the SN. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 153 • The selection of a Service Provider (SP) by the AN, based on user signalling is not possible since this would require the existence of SN functionality in the AN. • The establishment of VC and VPs in the AN is under the control of the SN at all times. The VB5.1 interface architecture is defined in detail by the ITU and ETSI in documents ITU-T Recommendation G.967.1 [25] and EN 301 005 [12] respectively. VB5.2 provides the additional functionality of been able to establish on demand/flexible provisioned VC and VP connectivity in the AN under the control of the SN. This achieved through the addition of a Broadband Bearer Connection (B-BCC) protocol that provides the mechanism by which the SN can request the AN to establish, modify and release VP and VC links on demand in the AN based on negotiated connection attributes such as traffic descriptors and Grade of Service/Quality of Service parameters. The VB5.2 interface architecture is defined in detail by the ITU and ETSI in documents ITU-T Recommendation G.967.2 [26] and EN 301 217 [14] respectively. With respect to the UNI for the support of broadband access networks, the FSAN Common Technical Specification specifies the use of the latest ATM Forum UNI architecture, presently UNI3.1. F.2.3 Physical Interfaces and Services Sets The FSAN is aimed at providing the following service sets: • Internet/Intranet Access; • VoD; • Midband asymmetric and symmetrical applications; • Interactive Multimedia Services; • Video Conferencing; • Business TV. Using the following delivery mechanisms: • Hybrid Fibre Coax; • ADSL/VDSL; • Fibre To The Curb; • Fibre To The Home. Within the FSAN architecture the following line rates are available for an Optical Distribution Network: • Option 1 Symmetrical 155,2 Mps; • Option 2 Asymmetric 155,2 Mbit/s upstream and 622,8 Mbit/s downstream; • Option 3 Asymmetric 25,92 Mbit/s upstream and 155,2 Mbit/s downstream. With the use of hybrid coax VDSL and fibre technologies the following line rates are available: • Asymmetric 2 Mbit/s upstream and 26 Mbit/s downstream with a VDSL reach of less than 1 km; • Asymmetric 2 Mbit/s upstream and 13 Mbit/s downstream with a VDSL reach of less than 1,5 km; • Symmetrical 13 Mbit/s to 26 Mbit/s with a VDSL reach of up 500 m. The FSAN Common Technical Specification specifies an overall bit error rate of one in 10-9 across the whole PON and one in of 10-7 across the VDSL network. Also the mean transmission time delay across the access network should be less than 1,5 ms as defined in ITU-T Recommendation G.982 [67]. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 154 The physical interface and service specifications for the SNI are shown in Table F.1. Table F.1: SNI Physical Interface and Service Specification Service Type IP Routing ATM Switch Virtual Circuits Video On Demand Switched DVB VP Leased Lines ISDN VB Interface Version 5.1 5.1 5.1, 5.2 5.1 5.1 5.1 Physical Interfaces 10BaseT ATM 25 Mbit/s ATM 25 Mbit/s ATM 25 Mbit/s ATM 25 Mbit/s ATM 25 Mbit/s ATM 155 Mbit/s ISDN ATM Services VBR CBR, VBR, ABR CBR CBR - - Bandwidth 10 Mbit/s 150 Mbit/s 6 Mbit/s 6 Mbit/s - - Peak access transmission delay 1,5 ms 1,5 ms < 1,5 ms < 1,5 ms - - Access Delay < 1 s - < 3,0 ms < 3,0 ms - - Response Time - - - < 500 ms - - Cell Loss - 10-5 10-8 - - - NOTE: With respect to VP/VC usage when a VC connection is set-up by the SNI the CAC function on the SNI needs to ensure that the bandwidth requested is available on the physical link. The number of simultaneous signalling links required for VB5.1 is four or more whilst 4 or more pairs are required for VB5.2. F.2.4 OLT Requirements F.2.4.1 Physical Interfaces The following physical interfaces are specified for the OLT: • ATM UNI (fibre 155,52 Mbit/s PON); • SDH 51,58 Mbit/s, 155,52 Mbit/s, 2,048 Mbit/s; • PDH 2,048 Mbit/s, 6,312 Mbit/s, 8,448 Mbit/s, 34,368 Mbit/s, 44,736 Mbit/s; • Circuit Emulation; • 10/100 BaseT. Also the system shall be capable of supporting and accommodating different line interface cards (non-duplicated and duplicated) simultaneously for the purpose of redundancy etc. Specifically the system shall accommodate the following maximum number of line interfaces in the case of non-duplicated configuration: • 32 or more for 2, 6,3, 8, 34, 45, 50, 150 Mbit/s interfaces; • 8 or more for 600 Mbit/s interfaces; • 4 or more for 150 Mbit/s interfaces. For circuit protection a duplicated or non-duplicated configuration shall be arbitrarily switchable for transport lines except the 2 Mbit/s, 6,3 Mbit/s, 8 Mbit/s, 34 Mbit/s and 45 Mbit/s interfaces. Furthermore the protection schemes shall comply with the ITU-T Recommendation G.783 [68] for duplicated configuration. F.2.4.2 Cell Switching Function The cell switching function shall have a 8x8 or greater matrix in terms of the 600 Mbit/s switch port and should exhibit non-blocking characteristics. The connection matrix should be capable of setting up both point to point and at least 1 to N multipoint connections, where N is 48 or more. The Cell Switching Function is also responsible for multiplexing cells based on their Virtual Path Identifiers (VPIs). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 155 F.2.4.3 ATM Transfer Capability (ATC) The OLT is required to support the following ATC's DBR classes 1,2 and U (UBR.1) as defined in ITU-T Recommendations I.356 [27] and I.371 [75]. Furthermore BT would like to see additional support for SBR (classes 2 and 3), GFR (classes 1 and 2) and ABR (class 3). Presently there is no requirement for ATM Block Transfer (ABT) capabilities. The system shall also be capable of multiplexing different ATC's into a transport line and an access-line so as to increase line utilization, whilst still retaining the required quality of service for each ATC feed. EPD/PPD shall be used for GFR. Parameters associated with the total access network will be qualified in terms of supported traffic parameters ranges and granularity, for example Peak Cell Rate (PCR) and Cell Delay Variation (CDV). In particular the access network shall be defined using worst case quality of service parameters, for example the upper bounds on CDV and Cell Loss Ratio (CLR). F.2.4.5 Call Connection Control Within the OLT, Usage Parameter Control (UPC) should be used for all set-up connections originating at an access-line interface. In contrast Network Parameter Control (NPC) should be used for all set-up connections originating at a transport line interface. UPC/NPC parameters to be compliant with ITU Recommendation I.371 [75]. The UPC/NPC shall discard, tag or pass on non-conforming cells for each connection. The Call Connection Control side of the OLT shall also be responsible for recording the number of passed cells, number of non-conforming cells and number of discarded cells. The OLT shall also support Cell Congestion Control by detecting QoS degradation for DBR classes 2 and UBR.1. Including EFCI/BECN compliance as per ITU Recommendation I.371 [75]. F.2.5 Network and Service Management F.2.5.1 Mapping onto TMN Architecture The network and service management architecture for the FSAN was defined by the Operations Administration and Maintenance Working Group with the basic aim to manage the range of services available from a common platform. The FSAN network and service management architecture is based on the ITU's Telecommunications Management Network (TMN) layered architecture defined in ITU-T Recommendation M.3010 [29]. The TMN management architecture is shown schematically below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 156 Increasing Level of Abstraction Business Management Layer Service Management Layer Network Management Layer Element Management Layer BML SML NML EML NE NE NE NE NE Network Element Layer NE Figure F.4: TMN Network Management Hierarchy The Network Element Layer (NEL) contains the physical resources called network elements. The following FSAN elements that can be mapped onto this layer are the following access network elements: Optical Line Termination (OLT), Optical Network Unit (ONU), Optical Distribution Network (ODN) and the drop medium. The Element Management Layer (EML) manages the physical resources and provides a common interface to the Network Management Layer (NML) for the various types of managed network elements. This layer is responsible for understanding the details of manufacturer specific information and equipment thus removing the need for this complexity of information to be held at the NML. It will contain a operations system (OS) which would normally deal with functions such as configuration, fault management and performance monitoring of the physical resources which reside in the access network. The interface between the EML OS (also known as the Element Manager) and the NML OS(s) is seen as a point for standardization. Typical management functions at this level are configuration, fault management and performance monitoring. The Network Management Layer (NML) provides the functionality to bind the individual network elements into the managed network. This is the layer where the co-ordination of multiple EML OSs is undertaken to provide overall network supervision. It provides the end to end configuration of services and also provides links between different network components to form a complete network. The Service Management Layer (SML) manages the services supported by the network and is less concerned with the physical nature of the network but more with the overall function. It also provides the customer interface. Service creation, provision, cessation billing and accounting information are some of the functions supported by this layer. The Business Management Layer (BML) is concerned with managing the complete undertaking, in accordance with the business objectives and customer requirements. F.2.5.2 FSAN Management Architecture It is proposed that FSAN services are managed using a TMM based architecture consisting of several interconnected management systems that control and monitor the architecture from predetermined reference points. The FSAN Management Architecture is shown schematically below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 157 SM OSF NE SN Extended Feeder if0 (IF0:Q3) if1 (IF1:Q3) if2 (IF2:SNMP/Q3) if3 (IF3:SNI) if3 (IF3:SNI) if4 (IF4) if5 (IF5) if6 (IF6:UNI) SML NML EML NEL Domain 2 Domain 1 if2 (IF2: SNMP/Q3) if7 (IF7:X) if8 (IF8:Q3/X) NM OSF EM OSF SM OSF SM OSF NM OSF EM OSF EM OSF EM OSF OLT DCN Network Element if4 (IF4) if4 (IF4) OLT ONU ONU ONT ONT ODN NT NT Figure F.5: FSAN Management Architecture The FSAN management architecture defines a management service and recommended protocol implementation for each management reference point, as listed in Table F.2. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 158 Table F.2: Services Provided over Management Interfaces Reference Point Management Services Comments on implementation of reference point if0 topology, service configuration and provisioning • trouble/test administration • account/billing/QoS performance reporting Q3 if1 configuration/provisioning/test/fault/performance management of transport resources • equipment management • configuration/fault/performance management of transmission system based on the TMN Q3 interface using the Common Management Interface Protocol (CMIP) Network Management Hierarchy if2 configuration/fault/performance/test management of network element • network element consistency checks • network element initialization/authentication/ security management SNMP initially but does not preclude migration to Q3. if3 termination of SNI • management/control/maintenance/testing of interface • connection establishment • mapping of bearer services to access transport resources SNI if4 multiplexing of bearer services • management communications • connection/fault/performance management • link initialization • media access control • security and user data encryption Management communications between OLT and ONU/ONT is via management channel over this interface. if5 error detection/reporting • fault detection/reporting • reset control • configuration/activation/deactivation of NT resource this reference point may not be implemented if the ONU and NT are combined as in the case of the ONT if6 termination of UNI • management/control/maintenance/testing of interface • activation/deactivation UNI if7 ordering, service configuration and provisioning • trouble/test administration • account/billing/QoS performance reporting X this interface should have special security aspects because it links two different domains if8 topology, ordering, service configuration and provisioning • trouble/test administration • account/billing/QoS performance reporting for the purposes of the service user Q3/X this interface should have special security aspects because it links a customer OSF to a network provider OSF The key issues to note from Table F2 is that the FSAN network management architecture is predominantly based on the ITU TMN model using the Common Management Interface Protocol (CMIP) for the Q3 and X interfaces. However it is interesting to note that the architecture also considers the availability of Simple Network Management Protocol (SNM P) interfaces for the management of network element layer equipment. With respect to the system architecture it is predicted that initially only the IF1 and some IF3 interfaces will be standardized, based on the Q3 and VB5.x interfaces respectively. However, it is desirable that interface IF2 is also standardized in the future to permit the EM OS and network elements to be procured from different suppliers. The TINA-C proposal of an open, distributed computing environment using building blocks with contract interfaces or the latest Common Object Request Broker Architecture (CORBA) could also be used as a possible framework which would lead to the adoption of a common standard for this interface. The FSAN OAM working group recommends that a consistent set of parameters are defined for each interface even if it is proprietary to allow future migration to a standard interface. In conclusion, the FSAN OAM group recommend that further study is needed on this and the other interfaces before any firm recommendation can be given. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 159 F.2.5.3 FSAN Management Requirements The FSAN management requirements can be summarized by the FCAPS acronym standing for Fault, Configuration, Accounting, Provisioning and Security aspects. The key requirements associated with the FSAN management architecture are discussed below. Automatic Control Function System faults should be automatically detected by the system self-diagnostics and then trigger an automatic switch over process between the standby and faulty unit or card. To aid the switch over process all systems should be capable of remembering their current and past card configuration. OAM Functionality The OLT and the FSAN management architecture shall be capable of performing the following OAM end-to-end measurements as defined in ITU-T Recommendation I.610 [76] to ensure facilitate the successful monitoring and reconfiguration of the physical layer resources: • F1 Signal detection and frame alignment flows. • F2 and F3 Error monitoring and automatic protection flows. • F4 Fault Performance monitoring information on Virtual Channels. • F5 Fault Performance monitoring information on Virtual Circuits. • AIS and RDI. • Performance and Monitoring. • Loopback. • Continuity Check. • VP and VC tests measuring the number of bit errors, lost cells etc. Configuration Management The ability to offer the following key configuration management functionality: • The registration and deletion of network elements and circuit cards. • Forced switch function if a network element suffers from a duplicated configuration. • Searching and listing functions for circuit card configurations including historical information as shown. • Management functions for the programme version installed in each network element. • Management functions for setting up PONS sections. • Management functions for assigning bandwidth to each ONT stream. • Management functions for setting up and releasing VP and VC connections at every termination point. • Management functions for setting up the NPC and UPC features. • Management of SNI and Circuit Emulation parameters. Fault Management Functions • The ability to deliver event reports related to various equipment sections, VPs and VCs. • The ability to identify rapidly switched events for failure protection. • The ability to conduct VP and VC test functions, loopback and continuity checks. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 160 Performance Management Functions • The ability to collect data (auto discovery), time stamp and save performance information. • Thresholding and alarm forwarding capabilities. • The ability to produce scheduled reports. • Configure and utilize OAM flows. • Capacity Management functions such as network equipment in use, spare equipment and faulty equipment, etc. Security Functions Security level for all management systems should be equal to or exceed the C1 standards defined in DoD 5200.28-STD. F.2.6 Future of FSAN The FSAN architecture was initiated and devised during the time when the vision of an ATM based core network was popular. However we are now in a time of uncertainty regarding the future core network architecture due to the vast growth of the Internet and IP based networks beginning to challenge the ATM stance. An example of this uncertainty is demonstrated by the fact that many ATM and traditional switch vendors are currently acquiring IP based network vendors to try and guarantee their future security, for example Nortel's recent acquirement of Bay Networks. Furthermore new standards such as MPLS, DIFFSERV and RSVP are been introduce to enhance the present day IP with desirable features from the broadband ISDN/ATM standards. For example IP is inherently un-guaranteed and connectionless, whilst ATM offers connection oriented guaranteed services. Multi-Protocol Label Switching (MPLS) claims to be the technology key that will open up the gate into New World IP VPN services by giving providers the ability to offer mega-scale, differentiated business IP VPN services with simpler configuration and management for both providers and subscribers. It is proposed that this will be achieved by using an innovative label-based forwarding paradigm, whereby labels indicate both routes and service attributes. At the ingress edge, incoming packets are processed and labels are selected and applied. The core reads the labels, applies appropriate services, and forwards packets based on the label. Processor-intensive analysis, classification, and filtering happens only once, at the ingress edge. At the egress edge, labels are stripped, and packets are forwarded to their final destination. The Internet Engineering Task Force (IETF) has issued a proposed standard for differentiated services (DiffServ), enabling either end-to-end or intradomain service discrimination. By establishing a way to deliver differentiated per-hop forwarding behaviour to IP packets, DiffServ allows a shared network to accommodate different QoS levels for traffic streams using the same infrastructure. DiffServ will enable Internet service providers (ISPs) to define classes of service (CoS) to support the particular requirements of consumer, business, commerce, and multimedia traffic, and to offer "premium" services for special data types such as voice. The Resource Reservation Setup Protocol (RSVP) is designed to be used by an IP based host to request specific qualities of service from the network for particular application data streams or flows. RSVP could also be used by routers to deliver QoS requests to all nodes along a route thus guaranteeing end-to-end quality/grades of service. Hence the long-term future of FSAN could really depend on whether the future core network will be ATM based as originally predicted or IP based. However for the Satellite environment an ATM environment has many advantages due to its end to end connectivity and management capabilities. F.2.7 Synergy with Satellite Systems Clearly the FSAN initiative has been to date focussed exclusively on terrestrial optical and wireline technologies, but the user applications and the approach to network management can be mapped onto the proposed future broadband satellite systems. For example many of the future broadband satellite systems proposed for launch in year 2003/4 have similar service sets and physical interfaces to that of the FSAN services, as shown in Table F.3. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 161 Table F.3: Example BSM System Service Sets System Orbit Technology Upstream Data rates Downstream Data rates Terminal Interfaces Teledesic LEO Fast Packet Switching 2 Mbit/s 64 Mbit/s IP, ISDN, ATM Astrolink GEO ATM Switching < 20 Mbit/s < 110 Mbit/s ATM, IP Skybridge LEO ATM Switching Res. 2 Mbit/s Bus. nx2 Mbit/s Res. 20 Mbit/s Bus. nx20 Mbit/s ATM, USB, Ethernet, ISDN, WAN, PBX Basically there are two option for generic satellite access networks, the first been to use transparent satellites which are capable of delivering packet based services over existing systems using ITU-T Recommendation X.25 [72], ATM, Frame Relay and IP technology and secondly the next generation satellites offering Onboard Processing (OBP) capabilities. With transparent systems that satellite access network can just be considered as a bent pipe delivery system since no processing is done above the physical layer. However with OBP next generation systems, the aim is to combine the multiplexing capability of ATM transport with advanced Medium Access Control (MAC) processing on board. With OBP, ATM-layer and above processing will be carried out on board the satellite. This principle parallels well with the FSAN architecture, which also assumes an ATM transport platform and performs multiplexing in the access network through the ONU. FSAN further maps onto broadband satellite systems with the key network intelligence been at the SN so that the AN can be managed from the SN. This bodes well for satellite systems since it can reduce the intelligence required on board to the minimum for operational reasons and reliability. One approach of mapping FSAN onto the proposed broadband satellite systems is shown below. SN Extended Feeder OLT ODN ONU NT ONT Access Network SNI User UNI SN Satellite Earth Station Gateway Satellite Access N/w NT Access Network SNI User UNI (OLT) Remote Satellite Terminal Eg. VSAT Figure F6: Mapping FSAN onto Satellite Access Network This mapping of FSAN is based on the following assumptions that: • a gateway satellite earth station can be considered as the satellite equivalent of an OLT; • the satellite access network can be considered as the satellite equivalent of the ODN with the satellite(s) acting as ONUs; • a remote satellite terminal can be considered as the satellite equivalent of a terrestrial NT unit. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 162 The above assumption can be used for mapping standard transparent satellite systems and the new OBP proposals. However the OBP issues needs further investigation since the level of intelligence on-board could move the satellite into areas traditionally addressed at the SN. It is also possible that the FSAN, TMN based, network management architecture that is currently been applied in many existing terrestrial networks can be mapped onto the management of future satellite systems. This is illustrated in Figure F.7 below. OS-F OS-F OS-F OS-F OS-F SML NML NEL EML Gateway Access Switch Satellite Network Operator Domain OS-F OS-F OS-F SP Domains Access Switch Satellite(s) NT DCN if7 (IF7:X) if1 (IF1:Q3) if8 (IF8:Q3,X) if2 (IF2:Q3) if2 (IF2:Q3) if4 (IF4) if3 (IF3:SNI) if4 (IF4) if5 (IF5) if6 (IF6:UNI) Service Node Figure F.7: Satellite mapping of FSAN Management Architecture With future broadband terrestrial and satellite systems it will become increasingly important for the end user, content provider and service provider to have dynamic management access to the resources of the access network. Presently satellite space segment is arranged by voice, fax or emails. Hence the satellite operators need to adopt a management system for the future capable of handling dynamic space segment requests between service providers, network operators and their own network management systems. The FSAN TMN based management architecture is an ideal vehicle for this issue since a TMN X interface could be adopted between the service provider/network operator and satellite operator service management platforms. However further work is required lower down the management stack since the majority of satellite based network equipment is not SNMP or CMIP compatible but instead based on proprietary ASCII and/or closed contact alarm management. This issue could be resolved with the use of SNMP/CMIP proxy agents. F.3 ATM Forum The ATM Forum has several different scenarios for the development of ATM based broadband access networks, two of which incorporate the VB5.1 and VB5.2 interfaces and hence are very similar to the FSAN initiative as discussed earlier. However the majority of their solutions differ from the ITU-T generic and FSAN approaches in that they place far more functionality within the AN itself, including the termination of user signalling. The aim behind this is provide more autonomy in the AN if there is significant intra-AN traffic and to reduce the signalling load on the core network. This may be particularly relevant to the proposed broadband satellite system, especially those of inter-satellite link capabilities. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 163 F.3.1 Residential Broadband Architecture The basic ATM Forum access network approach is defined in their Residential Broadband (RBB) architecture as shown in Figure F.8. Figure F.8: ATM Forum RBB Architecture The Core ATM network defined as containing one more ATM switches as well as been the location for network management and other application servers, as shown in Figure F.9. Figure F.9: ATM Core Network The ATM Access Network is comprised of two key elements: the ATM Digital Terminal (ADT) and the Access Distribution Network, as shown in Figure F.10. The Access Network termination (NT) defined as the functional grouping that connects the ATM Access Network to the home ATM network. UNI W is the interface at the Access Network side of the NT. UNI X is the interface at the home side of the NT. The function of the NT is dependent upon the Access Network and home network technologies. The NT may be either passive or active. Figure F.10: ATM Access Network ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 164 The Home ATM Network (HAN) is defined as been responsible for the connection of the Access Network Termination and the ATM End System(s). Realizations of the HAN may range from a simple transparent-pass-through passive network to a complete local network with switching functions. The HAN is comprised of two functional groups a Home Distribution Device and Home Distribution Network as shown in figure F.11. The Home Distribution Device performs switching and/or concentration of ATM virtual connections between the UNIX and devices connected to the home ATM network at UNIH (including support for ATM virtual connections between such devices). It may contain PHY, MAC or ATM layer functionality and may also contain signalling. The Home Distribution Device is optional and need not be present in all Home ATM Networks. Some of its functions could be realized together with the Network Termination in a single device. The Home Distribution Network transports ATM traffic to and from the ATM End System and may be implemented with a single point to point link, with a star configuration or with a shared media tree and branch topology. Figure F.11: Home ATM Network F.3.2 RBB Reference Interfaces F.3.2.1 Access Network Interface The Access Network Interface (ANI) is the interface between the Access Network and the Core ATM network. It is independent of any specific Access Network technology. This interface is based on the ITU-T VB5.1, VB5.2 and SNI network architecture model as described in ITU-T Recommendation G.902 [24]. The ATM Inter-Network Interface (AINI) is an interface between two ATM networks. The design of the AINI is based on existing intra-network protocol specifications, i.e., B-ISUP and PNNI. The AINI uses a subset of PNNI signalling to provide SVC services. The UNIW, UNIX and UNIH interfaces are specific to the Access Network technology, Access Network termination, Home Network and ATM End System. These interfaces support a cell-based UNI, or optionally a frame-based UNI for ATM transport between these elements, hence signalling may be terminated within the access network. A UNI as defined in the ATM Forum UNI 3.1 [37] and SIG 4.0 Specifications may be used as an ANI. In order to perform dynamic resource management, the ATM Forum perceive that the Access Network needs the following capabilities: • The capability to distinguish between cells belonging to different VCs (as well as to different subscribers) and to perform ATM or MAC layer concentration and/or switching. • The capability to perform cell-level scheduling. • The capability to perform Connection admission Control processes • The ability to process and possibly negotiate ATM service categories, traffic contracts and QoS. • Knowledge of its own resources and the capability to allocate them. This is where the ATM Forum approach strongly differs from the FSAN approach since they are advocating the use of network intelligence and ATM layer processing within the access network. In contrast the FSAN initiative restricts all network intelligence and ATM layer processing to the Service Node and Core Network infrastructure. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 165 However the ATM Forum appreciate that different commercial scenarios will require different levels of intelligence distributed across the core and access networks and hence have produced five key scenarios. In Scenario 1 (see Figure F.12), the Access Network serves as an ATM concentrator, and does not perform any dynamic resource management. In the control plane, all services and capabilities and usage accounting and billing are located in the Core ATM network. At the ANI, there is a signalling VCC, an ILMI VCC, and possibly other reserved VCCs for each UNI. Messages on these reserved VCCs are not interpreted or modified by the Access Network. The ANI in this scenario corresponds to the VB5.1 interface. Figure F.12: ATM RBB Scenario 1 In Scenario 2, the Access Network serves as an ATM concentrator, and performs dynamic resource management. In the control plane, all services and capabilities, switching, higher layer services and usage accounting are located in the Core ATM network. At the ANI, there is a signalling VCC, an ILMI VCC, and possibly other reserved VCCs for each UNI (see Figure F13). Signalling messages are not interpreted or modified by the Access Network. There is also a Bearer Connection Control protocol, and one VCC is reserved to carry it. The BCCP requires an additional information flow across the ANI. The ANI in this scenario corresponds to the VB5.2 interface. Figure F.13: ATM RBB Scenario 2 In Scenario 3 (see Figure F.14), the Access Network may perform dynamic resource management. It serves as either an ATM concentrator or as an ATM switch. The Access Network may provide services and capabilities in the control plane, but does not perform usage accounting. It may also provide switching and/or higher layer services, as long as there is no ATM layer usage based accounting for these capabilities. In order to provide these services, a service profile is present in the Core ATM network. At the ANI, the signalling VCC is shared among subscribers. Signalling messages are interpreted and possibly modified to the extent that the Access Network is able to: 1) negotiate the service category traffic contract and QoS parameters for the VCC; 2) support control plane services offered by the Access Network; 3) validate the Calling Party Number for the Core ATM network. This requires the Core ATM network to operate signalling protocol state machines at the UNI and ANI. The ANI is either an ATM Inter-Network Interface (AINI) or a UNI. In the latter case, the Access Network is the user side of the interface and the ATM core network is the network side. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 166 Figure F.14: ATM RBB Scenario 3 In Scenario 4 (see Figure F.15), the Access Network may perform dynamic resource management. It serves as an ATM switch. The Access Network may provide services in the control plane and/or higher layer services, and provides usage accounting. The Access Network includes a service profile and usage accounting records. At the ANI, the signalling VCC is shared among subscribers. Signalling messages are interpreted and modified to the extent that the Access Network is able to: 1) negotiate the service category, traffic contract and QoS parameters for the VCC; 2) remap VPI/VCI at the UNI W to VPI/VCI at the ANI; 3) perform usage accounting; 4) support any other control plane services that it offers. This requires the Core ATM network to operate signalling protocol state machines at the UNI and ANI. The ANI is either an ATM Inter-Network Interface (AINI) or a UNI. Figure F.15: ATM RBB Scenario 4 Scenario 5 (see Figure F.16) represents the case where proxy signaling is used in Scenarios 3 and 4. In this case, the signalling channel (or channels) between the Access Network and the Core ATM network does not traverse the ANI but is present on a different interface. This other interface may be either a UNI or an NNI between the access call processing agent and the Core ATM network. This may be of particular interest to Satellite Operators and SPs since this could be used to extend user signalling to the satellite system gateway for the centralization of network intelligence. This approach would then map more closely to the FSAN initiative. Figure F.16: ATM RBB Scenario 5 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 167 F.3.2.2 RBB Service Sets The service sets for RBB are: • Point to point and point to multipoint services as in UNI3.1. • VPCs and VCCs as specified in UNI3.1. • PVCs and SVCs as per UNI 3.1 [37]. • Traffic Management - CBR, nrt-VBR, rt-VBR, ABR and UBR service categories as per TM4.0. These are available across the following RBB Physical Interfaces: • ATM Fibre 25,6, 51,2 and 155 Mbit/s Private UNI. • ATM 25,6 Mbit/s Cable Category. • Automatic speed detection is available at remote end. F.3.3 ATM Network Management Reference Model The ATM Network Management architecture is different from the FSAN TMN approach in that it is a flat management architecture as opposed to a layered approach. The ATM network management architecture is fundamentally based on a series of M flows that are used to manage specific segments of the RBB architecture. The ATM network management is shown schematically in Figure F.17. Public UNI Private ATM Network Public ATM Network Public ATM Network ATM Device Management System M1 M2 M3 M4 M4 M5 Management System Management System BICI Private UNI Figure F.17: ATM Network management model In this model, M1 is the ATM management interface needed to manage an ATM terminal device. M2 is the management interface needed to manage a private ATM network. M3 is the management interface needed to allow a customer to supervise their use of their portion of a public ATM network. Within the M3 protocol there are two classes; class 1 for monitoring information only and class 2 for monitoring and control. M4 is the management interface needed to manage a public network service, including both network element management and service management functions. M5 is the management interface needed for management interaction between two public network providers. M3 functions defined in the present document include configuration, fault and performance management at this time. To date the ATM Forum has defined both SNMP and CMIP implementations (including MIBs) for the M4 flow. An SNMP implementation has also been defined for both M3 classes. While the M2, M3, M4 and M5 management definitions can provide a top down network wide view, they are not the only management functions relevant to ATM. The Interim Local Management Interface (ILMI) provides an ATM link- specific view of the configuration and fault parameters of a User Network Interface (UNI). The UNI also provides some layer management functionality via Operations Administration and Maintenance (OAM) cells. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 168 F.4 Digital Audio-Visual Council The Digital Audio-Visual Council (DAVIC) has recently produced a specification (DAVIC v1.4) defining the minimum specification for tools and the dynamic behaviour required by digital audio-visual systems for end to end interoperability across countries, applications and services. This is based on a set of defined reference points, information transfer interfaces, physical signal transfer interfaces, management flows and stacks. Key DAVIC definitions are: 1) The Access Network is defined as a part of the overall delivery system, containing a collection of equipment and infrastructure that link a number of service consumer systems to the rest of the delivery system through a single or limited number of common ports. 2) Access Control is defined as the provision of access services and protection against unauthorized interception. 3) Control Information is defined as information that may change the state of objects intercepting data flows for example a remote control channel up command. 4) The Distribution Network is defined as a collection of equipment and infrastructures that delivers information flows from the access network to the network termination elements of the access network. The core DAVIC functions are: • Bit Transport. • Session Transport eg. Point to Point, Point to Multipoint. • Access Control. • Navigation, Programme Selection and control. • Application launching. • Media Synchronization. • Application Control. • Presentation Control. • Usage Data. • User Profile. F.4.1 DAVIC System Reference Model Unlike the ITU-T and ATM Forum approaches the DAVIC specification also addresses the information flows between Content Providers, Service Providers and End Service Consumer systems as well as those between the access and core networks. Figure F.18 shows the reference points for the End Service Provider (ESP) to End Service Consumer (ESC) architecture. B End Service Provider Access Network C End Service Consumer D Figure F.18: DAVIC Plane Reference Model ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 169 Reference Point B represents a set of ESP-ISP (Internet Service Provider) interfaces that are local to the region and a set of ESP interfaces to objects in other regions. Reference Point C represents a set of ISP-ESC interfaces that are local to the region and a set of ESC interfaces to objects in other regions. Reference point D represents a set of interfaces between ESPs and ESCs in the same region. Information flowing through Reference Point D is transparent to the ISP. Figure F19 expands the reference points for the particular area of access networks. It is interesting to note that the DAVIC specifications include a Home LAN similar to the ATM Forum architecture. Content Provider Delivery System Service Provider System Delivery System Service Consumer System A11 A10 A9 A1 Service Provider Core N/W Access N/W Distribution N/W Network Termination Set Top Box A9 A4 A3 A2 A1 Delivery System User Premise Interface Access Termination System Home LAN End Termination System A1 A1* A20 A20* A5 A7 A6 Figure F.19: DAVIC System Reference Model Table F.4 defines the various A reference points within the DAVIC system reference model. Table F.4: DAVIC Reference Points Reference Point Information Flow A1 Service Consumer System to Distribution System A1* DAVIC Home Access Network A2 Distribution Network to Network Termination A3 Distribution Network to Access Network A4 Core to Access Network A5 Network related control flows A6 Service related control flows A7 Network related control and access links A8 Management Objects A9 Service Provider to Core Network/Distribution System A10 Delivery System to Service Provider A11 Content Provider to Delivery System A20 Access Termination System to Home LAN A20* Home LAN to End Termination System Concentrating on the A4 reference point: this is based on a fully digital ATM based interface supporting ATM SVC, PVC, VPI and VCI functions. The DAVIC architecture is similar to the FSAN initiative in that the following assumptions apply: • Signalling in the access network is transparent. • All local switching is performed in the core network. • Routing, channel concentration, user connection and OAM flows to be performed in the access network. • Billing and charging procedures are transparent to the access network. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 170 Also like the FSAN and ATM Forum approaches, DAVIC have adopted the ITU-T VB5.1 as the Access Interface Specification, but future versions may adopt VB5.2 as it matures with time. Dynamic allocation of the access network resources will be achieved using the VB5.2 Bearer Control Channel Connection protocol (B-BCC). Multiplexing of ATM UNI interfaces (VB5.1) within the DAVIC Access Network is permitted. However the concentration of upstream traffic on a per connection basis is not permitted. Downstream traffic can be assigned on a per connection basis by switches in the core network. Using the above reference points the DAVIC specification includes a specific mapping for asymmetric satellite based access network, as shown in Figure F.20. Service Provider A9 Core Network A4 Access Network A3 A2 User Premise Interface A1 A1* NT A1 Access Network A4 Figure F.20: Satellite Mapping for DAVIC reference points F.4.2 DAVIC Protocols and Physical Interfaces The DAVIC protocols and physical interfaces are similar to the FSAN and ATM Forum approaches in that they support IP, UDP and ATM running over the standard core network SDH, PDH, SONET, PSTN, ISDN interfaces. However they also support a 270 Mbit/s DVB interface. A Bit Error Rate of better than 1 in 10-9 is specified. Standard recommended media connector is RJ45. For satellite access, QPSK and shortened Reed Solomon encoding is recommended. F.4.3 DAVIC Network Management Architecture The DAVIC Network Management Architecture is reasonably open compared to the structured architectures associated with the FSAN and ATM Forum proposals. This is due to that different management scenarios are available to take into account the various issues surrounding where to allocate the network management and intelligence functions in the network. The DAVIC approach is also flexible in that many interfaces have been defined to work with either the TMN based CMIP or SNMP. Plus in the future the DAVIC council may consider the adoption of the new web based and object broker based management architectures such as CORBA. However all the DAVIC scenarios are based on a common set of "S" management information flows which are used to communicate between the various network elements. The common use of manager to manager communications is also recommended for example between the management system managing the access network and the management system running the core network. This information is referred to in Figure F.21 and Tables F.5 and F.6. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 171 Service Provider Core Network Access Network Set Top Box Manager Manager Manager Manager S4 S1 S2 S3 S4 S3 S5 S5 S5 S5 Figure F.21: DAVIC Management Architecture Table F.5: Management S Flow Descriptions Management Flow Description S1 Content information S2 Application service layer configuration S3 Session and Transport Service Layer information S4 Network Service Layer Control Information S5 Network Management Information Table F.6: Management Interface Implementation Options Management Interface Implementation NMS to Core Network CMIP or SNMP NMS to Access Network CMIP or SNMP NMS to Service Provider Server SNMP NMS to Set Top Box SNMP Manager to Manager CMIP or SNMP From Table F.6 it is interesting to note that only SNMP can be used to manage the Set Top Box and the Service Provider Server. F.4.3.1 Management Scenario 1 This is a scenario in which the end-to-end multimedia system is partitioned into two management domains based on provider boundaries. One management domain contains the Service Provider who owns the server. The second management domain contains the Delivery System provider who owns the Core Network, Access Network and the STB. These two management domains are managed by separate Management Systems to provide reliability in their portion of the end-to-end system. There is peer-to-peer communication between the two Service Management Systems (SMSs). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 172 Figure F.22: DAVIC Management Scenario 1 F.4.3.2 Management Scenario 2 This is a scenario in which the end-to-end multimedia system is partitioned into two management domains based on provider boundaries. One management domain contains the Service Provider who owns the server and the STB. The second management domain contains the network provider who owns the Core Network, and the Access Network. The two domains are managed by separate Network Management Systems. There is peer to peer communication between the two SMSs. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 173 Figure F.23: DAVIC Management Scenario 2 F.4.3.3 Management Scenario 3 This scenario is one in which the STB is owned by an End Consumer. The end-to-end multimedia system without the STB can now be partitioned into management domains based on the ownership of the several components of the system. Figure F.24: DAVIC Management Scenario 3 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 174 F.4.3.4 Management Scenario 4 This scenario shows a single enterprise scenario in which one provider owns the entire network. In this case, conceptually only one SMS is required to manage the network to provide reliable service. However to decrease complexity, the network can be partitioned into sub-networks to provide distributed management. Figure F.25: DAVIC Management Scenario 4 F.4.3.5 Management Scenario 5 In this scenario the Access Network provider also owns the STB. The end-to-end multimedia system can now be partitioned into management domains based on the ownership of the several components of the system as below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 175 Figure F.26: DAVIC Management Scenario 5 F.4.3.6 Management Scenario 6 In this scenario all resources belong to the network provider, however the network provider is selling capacity to service providers. Interactions, therefore, occur at the service level but all flowing within the DAVIC network are controlled by the network provider. Figure F.27: DAVIC Management Scenario 6 ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 176 F.5 ITU The key area of the ITU activity in this subject are based round ITU Recommendations: • ITU-T Recommendation M.3100 [77] for TMN architecture and implementation. • ITU-T Recommendation G.967.1 [25] for VB5.1 architecture and implementation. • ITU-T Recommendation G.967.2 [26] for VB5.2 architecture and implementation. • ITU-T Recommendation G.902 [24] framework for functional access networks. • ITU-R Recommendation M.817 [78] IMT 2000 Network Architecture. • ITU-R Recommendation M.818 [79] Satellite Operations within IMT-2000. • Performance of ATM via satellite issues draft recommendations. The key issues from the above recommendations have been incorporated into the FSAN clause of the present document. F.6 ETSI The key area of the ITU activity in this subject are based round ETSI Recommendations: • The VB5.1 architecture and implementation (EN 301 005-1 [80] ). • The VB5.2 architecture and implementation (EN 301 217-1 [82]). • The VB5 TMN interfaces (EN 301 271 [57] V1.1). The key issues from the above recommendations have been incorporated into the FSAN and ATM Forum clause of the present document. F.7 Telecommunications Industry Association The Telecommunications Industry Association (TIA) is also active in the area of broadband multimedia systems and has issued a standard TSB94 highlighting their recommended satellite ATM network guidelines. Key issues addressed within the present document are: • Aspects associated with satellite handovers; • Aspects associated with satellite routing; • ATM architectures for transparent satellites; • ATM architectures for satellites with OBP. F.7.1 Satellite Handovers TSB94 has identified that there are three key handover situations for satellite systems as shown in Table F.7. Table F.7: Satellite Handover Types Handover type Initiated by Performed by System Intra-satellite End User Satellite (beam switching) GEO/MEO/LEO Inter-hub Fixed Earth Station Fixed Earth Station LEO/MEO Inter-satellite End user, Fixed Earth Station or Satellite Fixed Earth Station or Satellite LEO/MEO ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 177 From Table F.7 it can be concluded that for inter-hub and inter-satellite handovers a terrestrial ATM based network may be needed between the ground based fixed earth stations. Also the rate of handover changes will vary dependent on the constellation used. F.7.2 Satellite Routing TSB94 discusses that routing for bent pipe ATM via satellite solutions is achieved by forwarding all the cells from the receiver module to the downlink transmitter module, i.e. there are no changes to the data format. However in contrast the OBP satellite ATM switch will be required to perform ATM VC, VP and P-NNI routing along with resolving media access issues dependent on the satellite configuration (point to point, mesh or interconnect). The OBP ATM switch will also be expected to perform traffic management issues such as connection admission and control, usage parameter control, cell discarding and traffic shaping. F.7.3 Transparent Satellite Architectures The TIA TSB94 standard has put forward three typical ATM network architectures for so called bent-pipe satellites. Since the satellites are transparent no processing above the physical layer is carried out on the satellite. • ATM network access to fixed terminals and interconnect between two fixed networks. Within this architecture it is assumed that the gateway earth station acts as a multiplexer and is connected to the ATM network by a NNI interface such as the ATM Forum's PNNI. If the satellite access network is used to interconnect two private ATM networks, the interface between the access points and the ATM networks can be PNNI. If the satellite access network is used to interconnect two public ATM networks the interface between the access points can be the ATM Forum BISDN Inter Carrier Interface (B-ICI). If the satellite access network is used to interconnect a private and a public ATM network the interface point can be a public UNI. The interface between the ATM user equipment and the satellite access network can be a public or private UNI. • Mobile ATM Network Access to provide ATM networks between moving and portable end devices. With this scenario the interface between the ATM user equipment and the satellite access network is a UNI with mobility support. The gateway earth station will need to be connected to a terrestrial ATM network via a NNI interface. • Mobile ATM Network Interconnect to provide interconnection between a mobile network and a fixed network or two mobile networks. In this scenario all interfaces need to be NNI with mobility support. F.7.4 OBP Satellite Architectures Regarding OBP Satellite ATM architectures the TIA standards recommend the following approaches: • For ATM network access architectures the use of UNI signalling between the access node and the satellite. NNI signalling between the satellite and hub ground earth station. • For ATM network interconnect architectures the use of NNI signalling between satellite and neighbouring ground ATM switches. • For Full Mesh ATM networks the use of UNI for direct ATM access and NNI for inter-satellite to fixed ATM switch communications. F.8 Common Elements and Key Differences After reviewing all the relevant standards and initiative it is clear that the following issues are common and hence should be considered for adoption in any future broadband satellite system proposal: • The use of the ETSI/ITU VB5 architecture at the SNI. • The use of the ATM Forum UNI, NNI and PNNI architectures at the UNI interface. • The use of TMN based manager to manager communications for end to end service management. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 178 • The use of some form of RTMC, B-BCC and Q2931 signalling. • The common use of physical interfaces and service sets. • The common use of asymmetric and symmetrical services. The above issues are shown schematically in Figures F.28 and F.29 which show all the domains and reference points for the various initiatives mapped onto a satellite access network. SNI VB5 UNI ATMF Satellite Access Network UNI (P)NNI VB5.1 RTMC VB5.2 RTMC & B-BCC UNI Service Node Access Switch NT User Core Network Gateway Access Switch Figure F.28: Common Interface Domains FSAN SNI, VB5 UNI, ATMF ATM-F ANI, VB5 UNI W UNI X DAVIC A9 A4, VB5 A3 A2 A1 A1*, UNI UMTS Yu Iu Uu Cu Service Node Access Switch NT User Core Network Gateway Access Switch Satellite Access Network Figure F.29: Cross Interface Signalling However the following differences exist across the various standards and initiatives: • The FSAN approach is based on transparent signalling and no intelligence in the access network. This maps ideally onto present day transparent bent pipe satellite systems, but may raise issues with OBP satellite system since this could be argued to include some intelligence. The FSAN architecture is also based on management from the core network, which is again ideal for satellite applications since it reduces the intelligence needed on board the satellite. • The ATM Forum approach is based on active signalling and ATM layer processing within the access network, which may map onto future broadband systems using OBP but is incompatible with present day transparent systems. However the use of signalling proxy agents may be able resolve this issue by moving the intelligence back to the core network. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 179 • The TIA activities have identified that a different ATM interface will be required at the satellite to gateway, satellite to satellite and satellite to remote terminal interfaces depending on the network configuration e.g. ATM interconnect or full mesh architecture and connection between public or private networks. • The DAVIC specification also highlights the issue of where to locate the network management and intelligence boundaries, e.g. who manages the user terminal equipment etc. • Finally there is the issue of running the VB5 RTMC and B-BCC over a satellite access link, i.e. will the round trip access delay effect their operation. F.9 Conclusions In conclusion it is recommended that future broadband satellite systems should at the minimum evaluate the use of the ITU/ETSI VB5 and ATM Forum UNI interfaces at the Service Node and Access Node Interfaces of their networks since these architectures are common across all the various standards. Areas identified for further investigation by ETSI are: 1) The effects of running the VB5 RTMC and B-BCC protocols over a satellite access network. 2) The advantages and disadvantages to be obtained from placing ATM layer and network management intelligence/processing on board future satellite systems and the associated mappings to the ATM and FSAN approaches. For example are there any advances of putting connection admission control and access based signalling on board as proposed by the ATM forum or maintain this functionality at the core network as proposed by the FSAN architecture. 3) The identification of what different ATM interfaces are required at the satellite to gateway earth station, satellite to satellite and satellite to remote terminal interfaces for different network configurations e.g. ATM interconnect or full mesh architecture and connection between public or private networks. 4) The development of TMN based X Co-operative interfaces between satellite operators, network providers and service provides to provide seamless network and service management capabilities. As well as identifying the network and service management boundaries in a broadband satellite multimedia environment, for example who manages the user terminal equipment. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 180 Annex G (informative): DVB-RCS Details The scope of the baseline specification is for the provision of the interaction channel for GEO satellite interactive networks with fixed return channel satellite terminals (RCST). The solutions provided are a part of a wider set of alternatives to implement interactive services for Digital Video Broadcasting (DVB) systems. For the purposes of this specification, the following informative reference applies: • DVB Commercial Requirements for Satellite Interactive Terminals (DVB-CM141). G.1 Reference Models G.1.1 Protocol Stack Model For asymmetric interactive services supporting broadcast to the user with narrowband return channel, a simple communications model consists of the following layers: • physical layer: Where all the physical (electrical) transmission parameters are defined. • transport layer: Defines all the relevant data structures and communication protocols like data containers, etc. • application layer: Is the interactive application software and runtime environments (e.g. home shopping application, script interpreter, etc.). A simplified model of the OSI layers was adopted to facilitate the production of specifications for these layers. The figure below points out the lower layers of the simplified model and identifies some of the key parameters for the lower two layers. Following the user requirements for interactive services, no attempt will be made to consider higher layers in this specification. Layer Structure for Generic System Reference Model Modulation Channel coding Freq. range Filtering Equalisation Power Access mechanism Packet structure Higher medium layers Proprietary layers (Network Dependent Protocols) Network Independent Protocols Figure G.1: Layer structure for generic system reference model ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 181 G.1.2 System Model The figure above shows the system model that is to be used for interactive services. In the system model, two channels are established between the Service Provider and the User: • Broadcast channel (BC): A unidirectional broadband Broadcast Channel including video, audio and data. BC is established from the service provider to the users. It may include the Forward Interaction path. • Interaction channel (IC): A Bi-directional Interaction Channel is established between the service provider and the user for interaction purposes. It is formed by. • Return Interaction path (Return Channel): From the User to the Service Provider. It is used to make requests to the service provider, to answer questions or to transfer data. It is a narrowband channel. Also commonly known as return channel. • Forward Interaction path: From the service provider to the user. It is used to provide some sort of information by the service provider to the user and any other required communication for the interactive service provision. It may be embedded into the broadcast channel. It is possible that this channel is not required in some simple implementations that make use of the Broadcast Channel for the carriage of data to the user. The RCST is formed by the Network Interface Unit (NIU) (consisting of the Broadcast Interface Module (BIM) and the Interactive Interface Module (IIM)) and the Set Top Unit (STU). The RCST provides interface for both broadcast and interaction channels. The interface between the RCST and the interaction network is via the Interactive Interface Module. Return Channel Satellite Terminal (RCST) Figure G.2: A generic system Reference Model for Interactive Systems G.1.3 Reference Model of the Satellite Interactive Network An RCST is e.g. a SIT or a SUT An overall Satellite Interactive Network, within which a large number of Return Channel Satellite Terminal (RCST) will operate, will comprise the following functional blocks: • Network Control Centre: A NCC provides monitoring and control functions. It generates control and timing signals for the operation of the Satellite Interactive Network to be transmitted by one or several Feeder Stations. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 182 • Traffic Gateway: A Traffic Gateway receives the RCST return signals, provides accounting functions, interactive services and/or connections to external public, proprietary and private service providers (data bases, pay-per-view TV or video sources, software download, tele-shopping, tele-banking, financial services, stock market access, interactive games etc.) and networks (Internet, ISDN, PSTN etc.). • Feeder: A Feeder transmits the forward link signal, which is a standard satellite digital video broadcast (DVB-S) uplink, onto which are multiplexed the user data and/or the control and timing signals needed for the operation of the Satellite Interactive Network. RCST NCC SAT FW SAT RT RCST RCST RCST NETWORK 1 NETWORK 2 Interactive Network Adapter Interactive Service Provider Broadcast Network Adapter Broadcast Service Provider FEEDER 2 STATION GATEWAY 2 STATION FEEDER 1 STATION GATEWAY 1 STATION DVB Forward Link 1 DVB Forward Link 2 RCST Return Link Figure G.3: Reference Model for the Satellite Interactive Network The forward link carries user traffic and signalling from the NCC to RCSTs. The signalling from the NCC to RCSTs that is necessary to operate the return link system is called "Forward Link Signalling" in the following. Both the user traffic and forward link signalling can be carried over different forward link signals. Several RCST configurations are possible depending on the number of forward link demodulators present on the RCST: • 1: standard; • 2: enhanced; • more than 2: universal. G.2 Forward Link The RCST shall be able to receive digital multimedia broadcast signals conforming to: • EN 300 421 [9]; • ETS 300 802 [10]; ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 183 • ETS 300 468 [11]; • EN 301 192 [13]; • EN 301 459 [17]; • ETR 154 [5]. G.3 Return Link G.3.1 Base-band Physical Layer and Multiple Access Specifications for the base-band physical layer are given. The figure below represents an example of the digital signal processing to be performed at the RCST transmitter side, from the energy dispersal of the serial information bit-stream, to the QPSK modulation representing the digital to analogue conversion. Energy dispersal Information data Reed Solomon encoder P/S Convolutional encoder X Y Puncturing Framing (preamble) C1=I C2=Q Baseband filtering QPSK modulation Modulated QPSK signal Framing Framing (postamble ) Figure G.4: Baseband signal processing with traffic burst framing as example RCST synchronization includes definition of: • Timing Control; • Carrier synchronization; • Burst synchronization; • Symbol clock synchronization; • Burst start time. There are four types of bursts: traffic (TRF), acquisition (ACQ), synchronization (SYNC) and common signalling (CSC). Any slot can contain any kind of burst, at the discretion of the operator or service provider. An illustration of valid combinations of slots is shown below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 184 A C Q Figure G.5: Examples of valid combinations of slots The burst formats, etc., are detailed under the following headings. • Traffic burst format; • Synchronization and acquisition burst formats; • Satellite Access Control header; • Common Signalling Channel burst format; • Bit numbering and Interpretation; • Transmission Order. G.3.2 Randomization for energy dispersal The return link data stream shall be organized in fixed length bursts. In order to comply with ITU Radio Regulations and to ensure adequate binary transitions, serial data bit stream in a burst shall be randomized. The polynomial of the Pseudo Random Binary Sequence (PRBS) shall be as the one of EN 300 421 [9], i.e. 1+x14+x15. G.3.3 Coding Coding for channel error protection is applied to traffic and control data only. The coding scheme allows, but does not impose, serial concatenation of two codes. The outer code is a by-passable Reed-Solomon (RS) code, whereas the inner code can be either the non-systematic convolutional code of EN 300 421 [9] or a Turbo code. The selected inner code is signalled by the NCC on the forward link. A bypassable CRC can also be applied on the bursts in order to allow error detection at the NCC. Details are given under the following headings. • CRC error detection code; • Outer coding (RS); • Inner coding (convolutional code); • Inner coding (Turbo code). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 185 G.3.4 Modulation The signal shall be modulated using QPSK, with roll-off factor of 35%. The specification will also include details on: • Bit mapping to QPSK constellation; • Baseband shaping and quadrature modulation; • Output power control; • Guard Time. G.3.5 Capacity Request Mechanisms All methods described below can be used by RCSTs for capacity requests. One or more of the methods may be employed in a Satellite Interactive Network. For the particular implementation, the RCSTs would be configured at the time of commissioning and/or during operation. • Prefix Method: This mechanism is based on a prefix (N= 0 to 7 Bytes, N configurable) attached to all traffic bursts. If N is non-zero, it carries control and management information from the RCSTs to the NCC, mainly composed of capacity requests. • Data Unit Labelling Method: This mechanism is based on pre-assigned values of the Data Unit Header to identify Data Units carrying control and management information from the RCSTs to the NCC. This method shall be consistent with the possible use of the Data Unit Header for routing/switching user information. • Mini-slot Method: This mechanism is based on a periodic assignment to all logged-on RCSTs of slots smaller than traffic slots. It carries control and management information from the RCSTs to the NCC and is used also for maintaining RCST synchronization. • Contention based Mini-slot Method: As per Method "3", but the mini-slot can be accessed by a group of RCSTs on a contention basis. The multiple-access capability is either fixed or dynamic slot MF-TDMA. The specification defines both a Frame and Super-frame format. G.4 Protocol and Sequences Procedures to allow a RCST to log-on to the satellite interactive network and for operations with the NCC and the gateways are defined. This includes an identification of the calling RCST, an optional ranging process to adjust timing, frequency, and power of the RCST, and a log-on procedure which gives an identification to the RCST that can be used to transmit meta-signalling to request traffic connections. The following subclauses explain into more details each one of these procedures, and the requirements for NCC elements. G.4.1 Initial Synchronization Following the power-up, the RCST acquires forward downlink (receiver) synchronization and proceeds as detailed below: • The RCST acquires coarse return link synchronization using the PCR that is transmitted by the NCC on the forward link. • The RCST continues to receive the PCR after initial synchronization. In the event that PCR synchronization is lost, the RCST shall cease transmission and re-initiate the synchronization procedure. • The RCST receives the burst time plan transmitted by the NCC at regular intervals. The BTP is contained in the Forward link Signalling. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 186 G.4.2 Network Entry Network entry defines: • Overall Events Sequencing; • Logon Procedure; • Acquisition Procedure (Optional); • Synchronization Maintenance Procedures (Optional); • Signalling Messages. G.4.3 Log-off Procedure The log-off procedure defines three classes: • General; • Normal; • Abnormal. G.5 Service support The slot allocation process shall support four capacity categories: • Continuous Rate Assignment; • Rate Based Dynamic Capacity; • Volume Based Dynamic Capacity; • Free Capacity Assignment. Details are given for each. G.6 Network management The specification defines the messages to allow a RCST to log-on to the satellite interactive network. These will be used to co-ordinate an identification of the calling RCST, a process to adjust the power of the RCST, and a log-on procedure which gives an identification to the RCST that can be used to transmit meta-signalling to request traffic connections. As a minimum set of requirements the RCST must comply with the Control and Monitoring Functions specified in an EN. Among others, the present document requires that the RCST is only allowed to transmit when it receives its control correctly. G.6.1 Protocol stack The protocol stack is based on the DVB/MPEG2-TS standard in the forward link and is based on ATM cells or MPEG2-TS Packets mapped onto TDMA bursts in the return link. There are two types: • RCST Type A (IP Only); • RCST Type B (ATM). ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 187 G.6.2 Mesh networks To be studied later. G.6.3 RCST Addressing On the Forward Link, RCSTs shall be uniquely identified by a physical MAC address and a logical address. The MAC address is a physical address stored in non-volatile memory. It corresponds to a unique RCST physical identifier. It shall follow the IEEE 802.3 [81] standard and shall consist of 48 bits. The value 0xFFFFFFFFFFFF shall be reserved for broadcasting to all RCSTs. This MAC address will be used to address MAC signalling between the NCC and the NIU. It will also be used to encapsulate IP datagrams into MPEG2-TS frames. The logical address is composed of two fields, the Group_ID and Logon_ID which are assigned to each RCST during logon. They are used for addressing individual RCSTs until logoff. (The Group_ID is probably, therefore, the same after the next logon.). • The Group_ID corresponds to a group of logged-on RCSTs. It shall consist of 8 bits. The value 0xFF shall be reserved for system use (contention mode on the return link). • The Logon_ID uniquely identifies the RCST within a group identified with the Group_ID. The Logon_ID shall consist of 16 bits. The value 0xFFFF shall be reserved for system use (contention mode on the return link). For a Type A RCST any data (user traffic) that is destined to a specific RCST shall be transmitted using the RCST MAC address. Any data (user traffic) that is destined to all Type A RCSTs shall be transmitted using the broadcast MAC address (0xFFFFFFFFFFFF). Independently, each protocol used at higher layers may impose its own addressing scheme, e.g. IP addresses, etc. G.6.4 Forward Link Signalling DVB defines a set of tables built upon the MPEG PSI tables to provide detailed information regarding the broadcast network. Such DVB tables are referred as the Service Information (SI) tables. In a two-way Satellite Interactive Network, consisting of a forward and return link via satellite, medium access control information and other signalling are communicated through the forward link and shall be transmitted in a DVB compliant manner. Thus, the specifications for Service Information (SI) in DVB systems shall apply. The forward link signalling consists of general SI tables, carrying information about the structure of the satellite interactive network, and RCST specific messages sent to individual RCSTs, private data fields defined for standard DVB-SI tables, special Transport Stream packets (PCR Insertion) and descriptors, including private descriptors for standard DVB-SI tables. It is recommended that the transmission interval for the relatively static tables be set to between 5 and 10 seconds as a reasonable compromise between signalling overhead and logon speed. The figure below gives an overview of the protocol stack for forward link signalling. The specifications also defines: • PCR Insertion TS Packet. • Repetition Rates. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 188 DVB-S SPT SCT FCT TCT TBTP TCM TIM MPEG-2 TS General SI Tables (MPEG-2 Table Format) RCST Specific Messages (DSM-CC private data format) CMT PCR Insert Private Sections Figure G.6: Protocol Stack for Forward Signalling G.6.5 Return Link Signalling • RCST synchronization and Identification messages. • Configuration parameters between RCST and NCC. • Other Messages for Network Management. • Burst Time Plan Exchange. G.6.6 Coding of SI for Forward Link Signalling • SI Table Mechanism. • DSM-CC Section Mechanism. • Coding of PID and table_id fields. G.7 Security, Identity, Encryption Security is intended to protect the user identity including its exact location, the signalling traffic to and from the user, the data traffic to and from the user and the operator/user against use of the network without appropriate authority and subscription. Three levels of security can be applied to the different layers: • DVB common scrambling in the forward link (could be required by the service provider). • Satellite interactive network individual user scrambling in the forward and return link. • IP or higher layer security mechanisms (could be used by the service provider and content provider). Although the user/service provider could use his own security systems above the data link layer, it may be desirable to provide a security system at the data link layer so that the system is inherently secure on the satellite section without recourse to additional measures. Also, since the satellite interactive network forward link is based on the DVB/MPEG- TS Standard, the DVB common scrambling mechanism could be applied, but is not necessary (it would just add an additional protection to the entire control stream for non-subscribers). This concept is shown in below. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 189 DVB-S MPEG-TS AAL5 IP Phy-layer Air Interface DSM-CC MPEG-TS ATM Forward Link Return Link AAL5 TDMA bursts ATM Higher layers individual user scrambling (ATM or DSM-CC Header clear) DVB Common Scrambling (MPEG header clear) IPsec or other IP security mechanisms Service provider Smart Card smartcard or (user_id + password) Application specific security DSM- CC Figure G.7: Security layers for satellite interactive network There can be more than one user per RCST and that such users will have security in their own right. Security is thus defined at a level higher than the individual RCST. On a user basis, an authentication algorithm may either check for user name and password on the client device or may use a Smart Card within the RCST. All data and control to and from each user may be scrambled on an individual user basis. Each user will have a control word for the return and the forward Link that does not allow anybody other than the NCC or the user himself to descramble the data, except for lawful interceptors such as country authorities. G.7.1 Authentication Authentication may be implemented by request for a user name or password on the client device. In the case of a PC used as the client device, the RCST does not need to carry any special implementation. However, if the RCST contains a proxy client, then the proxy may be able to authenticate itself to the NCC. This means that an authentication server may be implemented at the NCC, which manages the authentication of each user. Authentication could also be replaced by a Smart Card on the RCST, also used for the link layer individual control word encryption. G.7.2 Forward Link • DVB Common Scrambling could be required in the Forward Link. • Individual scrambling may be implemented at the section level, but the MAC address of the user may remain in the clear, since the RCST uses the MAC address to filter messages. G.7.3 Return Link • The client device may handle IPsec, so the router at the NCC may be able to handle IPsec. • Individual layer 2 scrambling may also be implemented, with the header of ATM cells scrambled as well. This signifies that the BTP may be used at the NCC in order to know the originating RCST for each burst, which allows to individually descramble each message accordingly. • Return link scrambling for RCSTs sending MPEG2-TS packets. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 190 Annex H (informative): System design issues and performance considerations for broadband satellite-ATM networks NOTE: This contribution has been prepared to assist the ETSI STF126 for the study on Broadband Satellite Multimedia. In the first four paragraphs an overview of some of the design issues involved in a broadband satellite network is given, followed by some initial thoughts on the possible standardization issues. Authors: I. Mertzanis, G. Sfikas, R. Tafazolli, B. G. Evans, Centre for Communication Systems Research (CCSR), University of Surrey, Guildford, Surrey, GU2 5XH, UK, Tel: +44 (0) 1483-259808, Fax:+44(0)1483-259504, Email: I.Mertzanis@ee.surrey.ac.uk. H.1 Satellite constellation The choice of the satellite constellation has a great impact on a broadband satellite-ATM system design. On the one hand systems that use GEO satellites (placed at about 36,000 km of altitude) give an almost static user behavior resulting in negligible handover probabilities and no need for virtual channel re-arrangement. On the other hand, systems using Low Earth Orbiting (LEO) satellites (placed at altitudes ranging from 500 km to 2 000 km) require a sophisticated handover algorithm and a methodology for accepting new calls, without affecting the quality of service requirements of all the active connections. The use of multi-beam non-geostationary (non-GEO) satellites with advanced on-board processing capabilities in future multimedia satellite communications networks is a great challenge [H1]. Non-GEO satellites can provide global coverage with higher elevation angles, satellite diversity and offer lower propagation delays with respect to GEO satellites [H2]. Smaller, high data rate user terminals can be used with an increased level of mobility/portability. Connection admission control is one of the main areas of concern in any network that needs to provide GoS/QoS guarantees. In non-GEO satellite networks after the call establishment phase, service interruption due to unsuccessful inter-spot-beam or inter-satellite handoff could always happen. Medium Earth Orbit (MEO) satellite networks seem to be a good compromise [H3] between the high orbital distances of the GEO systems (with no extra complexity for handoff) and the low earth orbital distances (with the very high handover rates due to the satellite movement). Systems that use MEO satellites provide large coverage areas and require a much smaller number of satellites to cover the whole earth than any LEO satellite system with global coverage. In addition, each satellite can stay in view for over 1 hour before a user must switch to the next satellite. The number of satellites that are visible any time from any particular User Terminal (UT) or GTW stations depends on the satellite constellation design in particular the satellite diversity. It is assumed that during the call set-up phase the UT selects the strongest signal among all the available frequencies that is usually transmitted by the highest satellite in the sky at that particular moment. H.2 Ground Network Infrastructure Another parameter that influences the selection of the satellite network architecture, is the dependency on the terrestrial network infrastructure. The satellite links are essential for inter-station signalling, when there is no terrestrial infrastructure deployed. For example, most GEO systems do not need ground station interconnection through terrestrial links, whereas non-GEO systems require only a few satellite links to the LESs, when ISLs are used; otherwise they highly depend on a fast backbone network. In GEO systems ISLs mainly handle the traffic between different regions of the earth and bypass the terrestrial links, whereas in most non-GEO constellations ISLs are essential in order to reduce the number of LESs. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 191 H.3 Satellite Access Interface and Protocol Stacks Two main scenarios for the satellite access network protocol can be envisaged [H4]. The first one uses ATM cell encapsulation and satellite specific protocols for establishing and managing a connection, whereas the second one provides a highly integrated solution with the ATM protocol stack and aims towards the definition of a new Satellite- ATM (S-ATM) protocol layer. The ATM protocol extensions over the air interface and the on-board processing capabilities are different for each protocol platform. As a result, there are still a lot of open issues for investigation before a final decision can be reached. A more general satellite packet switching approach increases the system flexibility to accommodate any future protocol standards without being restricted by adopting an ATM satellite switching solution. However, the second approach provides a highly optimized protocol architecture, especially if ATM is adopted as the transport mechanism for the future broadband communication systems. H.3.1 ATM Protocol Encapsulation Protocol encapsulation is a simple and easy to implement technique for passing arbitrary protocol information through the network entities that could not otherwise interpret specific information. In this scenario, the satellite protocol platform is designed to transparently support different user terminal standards through a proprietary, satellite specific, interface. The satellite access protocols are terminated at the gateway stations and are thus not seen by any external network. Therefore, no modifications to the existing protocol standards are necessary. This approach appears to be very attractive in systems that need to accommodate several different types of user terminals with a variety of protocol standards, when the ATM protocol is not the dominant transport mechanism. Circuit switching, packet switching, or even hybrid solutions for the on-board satellite processor, can be implemented for networks that use this type of protocol platform. However, in this approach it is very difficult to offer optimum performance to any particular protocol standard, resulting in protocol inefficiencies (related to the increased packet overheads). H.3.2 S-ATM access interface In a highly integrated satellite and ATM network scenario the protocol stack inside the satellite network boundaries is very similar to the standard ATM. However, the satellite components use the Satellite-ATM (S-ATM) layer, which replaces the standard ATM layer, in addition to the Medium Access Control (MAC) and the radio physical layers. Signalling for call control is based on the ITU-T Recommendation Q.2931 [73] protocol standard and is terminated at the Network Control Station (NCS). In the case of mobile or portable terminals future versions of B-ISDN signalling and standards can be supported in a highly integrated network environment. H.3.2.1 LLC layer protocol The use of an HDLC (High Data Link Control) protocol layer below the S-ATM layer complicates the protocol stack due to the size of the S-ATM cells. The use of a protocol similar to SSCOP (Service Specific Connection Oriented Protocol) with a single ATM cell payload per S-ATM packet requires very large buffers at both the gateway and the terminal sides. Furthermore, it adds considerably on the packet overheads and increases the complexity of both the transmitter and the receiver due to implementation of protocol timers, acknowledgments and re-transmissions. On the other hand, by moving a protocol such as SSCOP above the S-ATM layer a frame size that is larger than one ATM cell can be used (that improves the radio throughput at certain BERs) but this approach also complicates the protocol stack. SSCOP is an end-to-end protocol and has to be terminated at the GTW. As a result, the use of an LLC (Logical Link Control) layer is not so attractive for ATM support over a satellite network in the presence of powerful channel coding and interleaving. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 192 H.3.2.2 Retransmission mechanism based on Partial Packet Discard A more ATM oriented solution has been considered in [H4], assuming that retransmission of corrupted or lost data is performed end-to-end by high layer PDUs (Protocol Data Units). Assuming that the erroneous cells can be detected at the satellite switch, these cells and consecutive ones that belong to the same higher layer PDU can be dropped and hence reduce the traffic on the TDM (Time Division Multiplexing) downlinks and the fixed network. The increase in the complexity of this approach, when compared to the LLC case, is lower since no additional processing power is required and less overhead is employed per ATM cell. Only an indication of the last ATM cell of a higher layer PDU is required in the ATM cell header and an additional state per Virtual Channel (VC). However, such a mechanism reduces the throughput on the radio due to unnecessary retransmissions of the correctly received ATM cells within a corrupted higher layer PDU. From this point of view, the throughput on the radio link is equivalent to the "selective retransmission protocol", when a LLC protocol is used and to the "go back N" protocol, when end to end retransmissions are performed (N is the number of ATM cells per higher layer PDU). This mechanism has been proposed in [H5] as Partial Packet Discard (PPD). H.4 Resource management and control functions Special attention is needed to the problem of evaluating the performance of multi-rate, multimedia calls with different GoS/QoS requirements. The satellite is assumed to accommodate a regenerative payload, with multi-spot beam antennas and on-board "ATM-like" switching and queuing capabilities. Many broadband satellite systems have proposed advanced on-board satellite switching in order to make full use of the advantages that ATM technology can offer. However, due to the space segment constraints, a full ATM switch on-board satellite is not foreseen. Some of the resource management and control functions are placed on the ground segment; i.e the connection admission control and call control functions. As a result, the on-board satellite processing requirements are reduced only to the ATM traffic management and, where applicable, the uplink resource allocation. In a satellite-ATM network most of the supported ATM traffic classes such as Constant Bit Rate (CBR), rt-VBR (real-time Variable Bit Rate), nrt-VBR (non real-time Variable Bit Rate) operate on a fixed bandwidth allocation basis. The resources are allocated during the connection establishment phase and remain the same for the call duration. Available Bit Rate (ABR) has been defined in such a way that allows a dynamic rate adaptation according to the network conditions. A number of very interesting studies such as the ERICA and ERICA+ [H6,H7] have been reported that target towards the efficient traffic management in ATM networks and discuss the problem of ABR service support as part of a congestion control (or congestion avoidance) function, mainly for the terrestrial segment. An investigation that focuses on the ABR capacity estimation in a S-ATM system and the Connection Admission Control (CAC) strategy that needs to be adopted is given in [H8,H9]. An additional parameter has been taken into consideration for the calculation of the ABR available capacity; i.e. MAC uplink resource constraints that is not present in a terrestrial ATM network. Congestion control should only be invoked when the CAC function fails to effectively provide the requested QoS guarantees. By taking into account the resource utilization statistics of traffic models that handle the high priority traffic flows (i.e CBR rt-VBR and nrt-VBR), a new methodology for a two stage adaptive CAC has been developed. Simulation and/or analytical methods can be used for the performance evaluation of the ABR service in an S-ATM environment. Finally, the ATM buffer dimensioning rules for all the supported services are investigated and simulation results that demonstrate the resource availability for the ABR service are provided under different mixed traffic scenarios. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 193 Satellite CC & CAC MAC Resource Manager ATM Resource Manager Up-link Resource Control Down-link Resource Control On-Board Switch Control ATM N X N switching module ... ... In Ports 1 N ...... ... D o w n - li n k B e a m Cout D o w n - li n k B e a m Out Ports 1 N Class 0 Class 1 Class i .. .. .. .. U p l i n k B e a m Cin Class 0 Class 1 Class i .. .. .. .. U p l i n k B e a m Cin ATMService Classses MACService Classses RMController Cout CBR rt-VBR nrt-VBR ABR UBR CBR rt-VBR nrt-VBR ABR UBR S-ATMTerminal CC UPC MAC ATM End User NCS GateWay MF-TDMA TDM Figure H.1: Resource management and control functional block diagram of a S-ATM As shown in Figure H.1, the resource management and control functions are distributed between the space and the ground segment. The on-board satellite switch is responsible for providing full connectivity from any uplink to any downlink spot beam and it is controlled by the switch control unit and the Call Control (CC) and the CAC units. The physical location of the blocks that implement the CC and the CAC functions can be on the ground in order to reduce the on-board processing requirements. In such a way, all the UNI signalling overhead and the call state machine implementation can be directed to the NCS on the ground. Depending on the switch implementation and the information carried within the S-ATM cells, frequent routing table updates such on a per call basis could be avoided. As a result, the on-board switch control processing requirements are minimized. The uplink and downlink resource control units are responsible for the incoming and outgoing traffic management and control the input and the output ports of the ATM switch respectively. The overall network resource management is performed by the Resource Management (RM) controller which supervises the operation of the MAC and the ATM resource managers at the NCS. The RM controller dynamically measures the network performance criteria (GoS, QoS for all service classes) and instructs accordingly the MAC and ATM resource managers. At the S-ATM terminal side, the control plane protocols are responsible for establishing and maintaining each connection. The bandwidth on the air interface is controlled by the MAC layer and is shared among all active users terminals. The usage parameter control (UPC) is a control function that could be placed either at an UNI or NNI (in such a case is referred as NPC) interface in order to monitor the conformance of existing traffic contracts. Although such a monitoring algorithm is quite essential in networks where traffic contract violations could happen by having misbehaving traffic sources that could transmit cells in excess of the negotiated cell rates, in a S-ATM network the incoming traffic is regulated by the allocated MAC bandwidth units. A MF-TDMA access for the uplink and TDM for the downlink is considered for the satellite-ATM terminals. Gateways and other high data rate terminals that play the role of traffic concentration units and Time Division Multiplex (TDM) access is selected to be most efficient for both the uplink and the downlink. As a result, the existence of UPC or NPC at the Gateway side is more essential. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 194 H.4.1 MAC As in any other wireless system, MAC regulates the incoming traffic at the satellite network access points. Several studies [H10, H11, H12, H13, H14] based on Demand Assignment Multiple Access (DAMA) [H15] or DAMA-variants [H16] using a combination of random access and reservation based schemes have been conducted. One of the most important designing targets for a MAC scheme is to maximize the resource utilization while maintaining low delay guarantees. In addition, the protocol stability and low complexity of the control algorithm need to be considered. However, a large class of MAC protocols is not applicable for satellite communications [H17]. The reason is that, when comparing the performance of various MAC schemes for GEO satellite networks with multi-class service support, there is not a single winner. Their performance depends on the network topology, the traffic demand and type (i.e. symmetrical, asymmetrical, aggregation level, burstiness etc.) and the complexity of implementing the control algorithm. Keeping in mind that in a broadband satellite-ATM network various types of traffic need to be supported and the ATM on-board switch will route traffic coming from single user terminal up to high data rate multi-user terminals that need to share the same MAC control protocol, a tradeoff in performance versus complexity needs to be made. H.4.2 Mapping ATM service classes into the air interface Five distinct service categories have been specified by the ATM Forum to accommodate all the different applications: CBR, rt-VBR, nrt-VBR, ABR and UBR. It is assumed that all service classes except the UBR can share the same pool of uplink resources. In order to guarantee fairness and a fixed GoS for the other services, the UBR resources in the air interface should be taken by another pool of resources with the use of a moving boundary. Since there are no minimum rate guarantees for the UBR service or any strict delay requirements, a hybrid approach which combines both random access and reservation based resource allocation at the air interface could be used. In this way, some level of multiplexing at the MAC layer can be achieved for a large number of bursty sources, as long as the system remains in a stable state and there is enough buffering space in the network [H18]. At the ATM layer, an effective CAC algorithm should take into account all these requirements in order to provide certain levels of QoS to all services classes that share the same downlink. During the call set-up phase, the CBR, rt-VBR and nrt-VBR services are assigned a fixed number of uplink slots, which remain constant for the duration of the call. Therefore, some multiplexing gain can be achieved only at the ATM layer by limiting the available resources at the ATM switch output queues. For the ABR service, a more flexible access scheme is assumed since it does not have delay requirements as strict as the rt-VBR. An ABR call is accepted or blocked at the MAC layer according to its Initial Cell Rate (ICR), or Minimum Cell Rate (MCR) requirements. After the call is accepted, all the slots that remain free in the uplink direction can be shared among all ABR users in order to satisfy the instantaneous requirements for increased bandwidth. If we want to maintain certain call blocking rates for all the supported service classes at the MAC layer, the available slots which are shared among all ABR services should be used in such away, as not to affect the new call blocking rate of any service type. One of the most recent arguments within the ATM Forum study groups concerning the required congestion control scheme for the ABR service was the selection between rate-based and credit-based control loop. Furthermore, a third proposal that is reported in [H19] suggests the integration of both rate and credit based proposals to coexist in order to make use of the advantages of each method in certain network topologies. The rate-based scheme that has been selected by the ATM forum seems to adapt better in WANs with large propagation delays and therefore seems a more appropriate scheme for satellite communications. H.4.3 Virtual connection tree concept in non-GEO networks In the last years, a few proposals appeared in the literature suggesting possible ways to overcome the user/terminal mobility problems in wireless ATM networks. A comparison among some of the most recent re-routing and virtual path re-establishment algorithms that can support handoffs in wireless ATM networks can be found in [H20]. However, the mobility issues related to satellite-ATM networks, are not fully covered yet. In a dynamic satellite-ATM network, the "virtual connection tree" concept [H21] can be applied as suggested in [H22]. This idea was also supported in [H23] where a new adaptive routing algorithm applicable in LEO networks with inter-satellite links is presented. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 195 H.5 Standardization Issues A few studies that have been submitted to the ATM forum concentrate on the WATM issues for the satellite segment. In [H24] an overview of the standardization activities mainly within ITU-R is given focusing on the ATM performance objectives for a satellite link. An introduction to the working plans of the Infrastructure and Satellite Access Sub Group is given in [H25] that includes the list of some initial activities. In [H26] the requirements in mobile airborne platforms are given. The present document can be used as a reference for discussion since it includes a list of WATM requirements at different protocol layers. Another study concentrates on the existing techniques for ATM multicast over highly assymetric satellite links [H27]. It is important to mention that one of the very first tasks of a study is to define certain performance objectives for each service class that it is supported through a broadband satellite system. H.5.1 Areas of study Some of the possible areas for discussion by the ETSI working groups are: • Network architecture and communications interfaces (includes ground network and inter-station signalling); • Service classes and performance objectives; • Medium Access Control schemes; • Air Interface - transmission rates - rate granularity - coding scheme; • Mapping service classes into the air interface; • Traffic management and QoS provisioning; • Signalling and connection establishment issues; • On-board satellite buffering and routing; • Addressing issues; • Multicasting. Interworking between protocol standards such as ATM, IP, N-ISDN, Frame-Relay etc. One of the most important areas for discussion is the possibility to provide a common standard (or maximum two) for the air interface. Most of the planned broadband satellite systems consider the use of a common fixed-size packet for the air interface that accommodates one or more ATM cells. An optimum satellite packet length for all the supported service rates and terminals is not envisaged, however at least two possible frame structures can be standardized to be used by different terminal types. Another area of study is the MAC scheme and the provision of bandwidth on demand. Recent studies that give a comparison of widely known MAC schemes seem to support the idea of a simple DAMA based algorithm [H17, H28]. Implicit reservation is used to (i.e content in a slotted Aloha channel) for the first bandwidth request since it is the most appropriate scheme for a large number of terminals. The next important area for discussion is the signalling and higher layer protocols. The adoption of a common signalling standard for the satellite segment will be beneficial even when several different standards for the air interface exist. Having specified a certain number of service classes that can be supported over the air interface the same performance objectives can be standardized per service class. The service mapping, the QoS provisioning and traffic management are network specific functions that could be excluded from the standardization process. However, extensive studies on these areas will provide the means for network dimensioning and reference models for performance evaluation. Finally the interworking between any future broadband satellite multimedia standard and the existing protocol standards needs to be carefully considered. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 196 H.6 References to Annex H [H1] A. Sammut, I. Mertzanis, R. Tafazolli, and B.G Evans "GIPSE: A Global Integrated Personal Satellite Multimedia Environment", Fourth European Conference on Satellite Communications (ECSC-4) Rome, 18 to 20 November 1997. [H2] Vatalaro, G. Corazza, C Caini: "Analysis of LEO, MEO and GEO Global Mobile Satellite Systems in the presence of Interference and Fading", IEEE JSAC VOL.13, NO.2, February 1995. [H3] F Ananasso and M. Carosi, "Architecture and Networking issues in satellite systems for personal communications", International Journal of Satellite Communications, VOL.12, 33-44, 1994. [H4] I. Mertzanis, G. Sfikas, R. Tafazolli, B. G. Evans, "Protocol Architectures for Satellite-ATM Broadband Networks", IEEE Communications Magazine, special issue on Satellite-ATM Network Architectures, March 1999. [H5] Allyn Romanow and Sally Floyd, "Dynamics of TCP traffic over ATM Networks", IEEE JSAC, Vol.13, No.4, pp.633-641, May 1995. [H6] R. Jain, S. Fahmy, S. Kalyanaraman and R. Goyal, "The ERICA Switch Algorithm for ABR Traffic Management in ATM Networks, Part II Requirements and Performance Evaluation", http://www.cis.ohio- state.edu/~jain/papers.html. [H7] R. Jain, S. Kalyanaraman, R. Goyal, S. Fahmy and, R.Viswanatham,"The ERICA Switch Algorithm for ABR Traffic Management in ATM Networks, Part I: Description", http://www.cis.ohio-state.edu/~jain/papers.html. [H.8] I. Mertzanis, G. Sfikas, R. Tafazolli, B. G. Evans, "Satellite-ATM; System design issues for Broadband Multimedia services", Journal of Defence Science, DERA, April 1999. [H9] I. Mertzanis, R. Tafazolli, B. G. Evans, "Satellite-ATM Network Dimensioning and ABR Capacity Estimation in the presence of self-similar traffic", Will appear in Fifth Ka-Band Utilization Conference, Taormina, Italy October 18-20, 1999. [H10] D. K. Guda, D. L. Schilling, and T. N. Saadawi, "Dynamic reservation multiple access technique for data transmission via satellites", IEEE INFOCOM'82, pp.53-61. [H11] C.F. Pavey, R.Price, Jr., and E.J. Cummins, "A performance evaluation of the PDAMA satellite access protocol", INFOCOM'86 Apr. 1986, pp. 580-589. [H12] K. S. Kwak and K.J Lim, "A modified PDAMA protocol for mobile satellite communications systems", IEEE JSAC, VOL.13, NO.2, February 1995. [H13] S. Bohm, A. K. Elhakeem, K. M. S. Murthy, M. Hachicha, and M. Kadoch, "Analysis of a movable boundary access technique for a multiservice multibeam satellite system", International Journal Of Satellite Communications, VOL.12, 299-312,1994. [H14] T. Le Ngoc and S. V. Krishnamurthy, "Perrormance of combined free/demand assignment multiple-access in satellite communications", International Journal Of Satellite Communications, VOL.14, 11-21,1996. [H15] T. T. Ha, "Digital Satellite Communications", 2nd Eedition, McGraw Hill, 1990 chapter 7. [H16] T. Ors, Z.Sun and B. G. Evans, "An adaptive random-reservation MAC protocol to quarantee QoS for ATM over satellite", Broadband Communications: The future of telecommunications (IFIP TC6/WG6.2 Fourth International Conference on Broadband Communications, Stuttgart-Germany, 1-3 April), pp. 107-119, ISBN 0-412-84410-9, Chapman and Hall, London, 1998. [H17] H. Peyravi, "Medium Access Control Protocols Performance in Satellite Communications", IEEE Communications Magazine, March 1999. [H18] I. Mertzanis, G. Sfikas, R. Tafazolli, B. G. Evans, "Multimedia Service Support for WISDOM: The Satellite Component of an End-to-End ATM Network", 4th ACTS Mobile Summit, 8th-11th June 1999, Sorrento, Italy. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 197 [H19] K. K. Ramakrishnan, P. Newman, "Integration of Rate and Credit Schemes for ATM Flow Control", IEEE Network, March/April 1995, pp.49-56. [H20] Akyol and D cox, "Rerouting for handoff in a wireless ATM network", IEEE Personal Communications, October 1996, Vol.3, No.5. [H21] D. Levine, I. Akyildiz and M. Naghishineh, "A resource Estimation and Call admission Algorithm for wireless multimedia networks using the shadow cluster concept, IEEE/ACM Transactions On Networking, VOL.5, NO.1 February 1997. [H22] I. Mertzanis, R. Tafazolli, B. G. Evans, "Connection Admission Control strategy and routing considerations in multimedia (NON-GEO) satellite networks", IEEE VTC'97, Phoenix, USA, May 1997. [H23] M Werner, "A dynamic routing concept for ATM based satellite personal communication networks", IEEE, JSAC VOL. 15, NO 8, October 1997. [H24] ATM Forum/98-0828. [H25] ATM Forum/98-0735. [H26] ATM Forum/97-0062. [H27] ATM Forum/98-0711. [H28] D. P. Connors, B. Ryu and S. Dao, "Modelling and simulation of Broadband Satellite Networks Part-I: Medium Access control for QoS provisioning", IEEE Communications Magazine, March 1999. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 198 Annex I (informative): Example of Satellite ATM Network Architectural Model The figure below illustrates the network architecture of an ATM network with user access by satellite. It is from a paper by the Univ. of Surrey (Protocol Architectures for Satellite ATM Broadband Networks, by Ioannis Mertzanis, Georgios Sfikas, Rahim Tafazolli, and Barry G. Evans, University of Surrey [44]). The entities and interfaces identified are also relevant in general i.e. for non-ATM-based satellite networks. Figure I.1: Satellite ATM reference network configuration Most of the future broadband satellite systems share common characteristics with the satellite network architecture, onboard satellite processing and switching capabilities, user terminals, supported protocol standards, the access scheme, and interconnection to terrestrial networks. Therefore, in a typical broadband satellite system the following network entities are considered: User Terminals (UT) - UTs might support several different protocol standards such as: ATM User Network Inter-face (ATM-UNI), Frame Relay UNI (FR-UNI), Narrowband Integrated Services Digital Network (N-ISDN) Basic Rate Interface (BRI), N-ISDN Primary Rate Interfaces (PRI), Transmission Control Protocol/Internet Protocol (TCP/IP). UTs are connected to the satellite adaptation unit (SAU) through one of the supported standard interfaces. Satellite Adaptation Unit - This is in general a specially designed unit, responsible for providing access to the satellite network. It performs all the necessary user terminal protocol adaptations to the satellite protocol platform. The SAU also includes all physical layer functionalities such as channel coding, modulation/demodulation, the radio frequency parts, and the antenna section. A set of various types of terminals, with a variety of transmission capabilities, is usually offered by a satellite network. Starting from minimum transmission rates of 8 or 16 kb/s, they can cope with maximum transmission rates of 144 kb/s (or 384 kb/s for personal type user terminals), or 2048 kb/s and higher for fixed type terminals with larger antennas. All of the supported terminals share the same access scheme and protocol stacks. Payload (P/L) - Full onboard satellite signal regeneration is assumed in most of the future broadband satellite systems. The onboard satellite processing units perform multiplexing, demultiplexing, channel coding/decoding, and fast packet switching using a multispot beam configuration. In some onboard proposals, "ATM-like" switching is suggested. These switching units are experimental or currently under development and include only part of the functionalities that a ground ATM switch would perform. Most of the power hungry processing operations such as call setup signalling termination or connection admission control (CAC) are performed on the ground. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 199 Gateway Stations (GTW) - These are the land Earth stations that provide connectivity to the external networks. In geostationary Earth orbit (GEO) systems the placement and number of GTWs on the ground segment depend mainly on the traffic demand. A large number of gateways is expected in geographical areas where the traffic demand is high and these gateways are always connected using the same satellite(s). However, in non-GEO systems the number and placement of the gateway stations depends on some additional system design characteristics such as: constellation design, use (or not) of intersatellite links (ISLs), and the overall end-to-end system delay budgets. For example, in a global medium Earth orbit (MEO) system with no ISLs, a total number of less than 10 gateways can provide full connectivity to the land masses most of the time. A low Earth orbit (LEO) system will require tens to hundreds of gateways, but this number can be reduced with the use of ISLs. Network Control Station (NCS) - This is a central entity, used in a GEO satellite system (usually one per satellite) that provides overall control of satellite network resources and operations. This node is responsible for allocating radio resources to the GTWs according to a long-term resource planning scheme. The NCS is responsible for performing call routing and call management functions such as location update, handoff (when applicable), authentication, registration, "deregistration", and billing. In non-GEO systems these operations are usually performed in more than one GTWs in a distributed manner. The above model is also very much in line with ITU-R considerations, as evidenced by the following excerpt from a Report of the Eleventh Meeting of ITU-R Working Party 4B (Geneva, Switzerland 26 - 30 April 1999) ITU-R Working Party 4B: The satellite network is represented by a ground segment, a space segment, and a network control center. The ground segment consists of ATM networks that may be further connected to other legacy networks. The network control center (NCC) performs various management and resource allocation functions for the satellite media. Inter-satellite links (ISL) in the space segment provide seamless global connectivity to the satellite constellation. The network allows the transmission of ATM cells over satellite, multiplexes and demultiplexes ATM cell streams from uplinks and downlinks, and maintains the QoS objectives of the various connection types. The satellite-ATM network also includes a satellite- ATM interface device connecting the ATM network to the satellite system. The interface device transports ATM cells over the frame based satellite network, and demultiplexes ATM cells from the satellite frames. The device typically uses a DAMA technique to obtain media access to the satellite physical layer. The interface unit is also responsible for forward error correction techniques to reduce the error rates of the satellite link. The unit must maintain ATM quality of service parameters at the entrance to the satellite network. As a result, it translates the ATM QoS requirements into corresponding requirements for the satellite network. This interface is thus responsible for resource allocation, error control, and traffic control. This architectural model presents several design options for the satellite and ground network segments. These options include: 1) No on-board processing or switching. 2) On-board processing with ground ATM switching. 3) On-board processing and ATM switching. More than half of the planned Ka-band satellite networks propose to use on-board ATM like fast packet switching a simple satellite model without on-board processing or switching, minimal on-board buffering is required. However, if on-board processing is performed, then on-board buffering is needed to achieve the multiplexing gains provided by ATM. On-board processing can be used for resource allocation and media access control (MAC). MAC options include TDMA, FDMA, and CDMA and can use contention based, reservation based, or fixed media access control. Demand Assignment Multiple Access (DAMA) can be used with any of the MAC options. If on-board processing is not performed, DAMA must be done by the NCC. On-board DAMA decreases the response time of the media access policy by half because link access requests need not travel to the NCC on the ground any more. In addition to media access control, ABR explicit rate allocation or EFCI control, and UBR/GFR buffer management can also be performed on- board the satellite. On-board switching may be used for efficient use of the network by implementing adaptive routing/switching algorithms. Trade-offs must be made with respect to the complexity, power and weight requirements for providing on-board buffering, switching and processing features to the satellite network. In addition, on-board buffering and switching will introduce some additional delays within the space segment of the network. For fast packet or cell switched satellite networks, the switching delay is negligible compared to the propagation delay, but the buffering delay can be significant. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 200 Bibliography The following material, though not specifically referenced in the body of the present document (or not publicly available), gives supporting information. - ITU-T: "Access Network Transport Standardization Plan", Issue 2, June 1999, ITU-T Study Group 15. - ITU-R, Radiocommunication Study Group 4: "Questions assigned to Radiocommunication Study Group 4, Fixed Satellite Service". - ITU-R, Working Party 4B, Draft new question: "Performance objectives of digital links in the fixed satellite service for transmission of IP packets". - ITU-R activities on digital broadcasting, RAST, Williamsburg, Virginia, USA, 23-26 August 1999. - ITU-R Working Party 4B: "REPORT OF THE ELEVENTH MEETING OF WORKING PARTY 4B", Geneva, Switzerland, 26-30 April 1999. - TIA: Standards and spectrum activities under TIA satellite communications division (SCD), TR-34 GSC#5/RAST#8, RAST, Williamsburg, Virginia, USA, 23-26 August 1999. - TIA: Evaluation Report by TIA TR-34 Ad Hoc IMT-2000 Satellite RTT Evaluation Committee. - ETSI, TR 101 119: "Network Aspects (NA); High level description of number portability". - ETSI, TR 101 122: "Network Aspects (NA); Numbering and addressing for Number Portability". - ETSI, TR 101 697: "Number Portability Task Force (NPTF); Guidance on choice of network solutions for service provider portability for geographic and non-geographic numbers". - ETSI, TR 101 698: "Number Portability Task Force (NPTF); Administrative support of service provider portability for geographic and non-geographic numbers". - ETSI, EG 201 367: "Intelligent Network (IN); Number Portability Task Force (NPTF); IN and Intelligence Support for Service Provider Number Portability". - EU, Commission Directive 96/19/EC, OJ L74, 223.96. - EU, Green Paper on the convergence of the telecommunications, media and information technology sectors, and the implications for regulation, COM(97)623. European Commission, Brussels, 3 December 1997. - ETSI Ad Hoc Group on Fixed/Mobile Convergence Final Report, ETSI GA30(98)Temp. Doc. 05. - ETSI, TR 101 019 (V1.1): "Users' Requirements; Mobility; Interworking and interoperability between networks". - ETSI, TR 122 970: "Universal Mobile Telecommunications System (UMTS); Service aspects; Virtual Home Environment (VHE) (3G TR 22.970 version 3.0.1 Release 1999)". - ETSI, TR 122 971: "Universal Mobile Telecommunications System (UMTS); Automatic Establishment of Roaming Relationships (3G TR 22.971 version 3.1.1 Release 1999)". - ETSI, TS 123 101: "Universal Mobile Telecommunications System (UMTS); General UMTS Architecture (3G TS 23.101 version 3.0.1 Release 1999)". - ETSI HLSG, High Level Strategy Group for ICT HLSG 99/33, HLSG Report No. 4: "Strategic Recommendations for 'Intelligent Multimedia Networking'". - P. Chitre and F. Yegenoglu, "Next generation satellite networks: Architectures and implementations", IEEE Communications Magazine, March 1999. ETSI ETSI TR 101 374-2 V1.1.1 (2000-03) 201 History Document history V1.1.1 March 2000 Publication |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 1 Scope | The present document surveys the current scenario and the status of proposals from both existing and future satellite operators, for provision of broadband multimedia services via satellite (broadband satellite multimedia). The information presented is available as a basis for further discussions within ETSI and the European Commission regarding the requirement for the development of standards applicable to equipment and systems to be used to provide such services. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • For a non-specific reference, the latest version applies. • A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. [1] Final Acts WRC-97 (ITU Radiocommunications Bureau). [2] ERC/DEC/(97)03: "ERC Decision of 30 June 1997 on the Harmonised Use of Spectrum for Satellite Personal Communication Services (S-PCS) operating within the bands 1610-1626.5 MHz, 2483.5-2500 MHz, 1980-2010 MHz and 2170-2200 MHz". [3] ERC/DEC/(97)05: "ERC Decision of 30 June 1997 on free circulation, use and licensing of Mobile Earth Stations of Satellite Personal Communications Services (S-PCS) operating within the bands 1610-1626.5 MHz, 2483.5-2500 MHz, 1980-2010 MHz and 2170-2200 MHz within the CEPT". [4] ETSI GMM Report: Global Multimedia Mobility. [5] EN 301 359: "Satellite Earth Stations and Systems (SES); Satellite Interactive Terminals (SIT) using satellites in geostationary orbit operating in the 11 GHz to 12 GHz (space-to-earth) and 29 GHz to 30 GHz (earth-to-space) frequency bands". [6] EN 301 358: "Satellite Earth Stations and Systems (SES); Satellite User Terminals (SUT) using satellites in geostationary orbit operating in the 19,7 GHz to 20,2 GHz (space-to-earth) and 29,5 GHz to 30 GHz (earth-to-space) frequency bands". [7] EN 300 421: "Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for 11/12 GHz satellite services". [8] STF126 Questionnaire: Broadband Satellite multimedia (www.etsi.org/ses/news/BroadSat.htm) [9] Memorandum of Understanding to Facilitate Arrangements for Global Mobile Personal Communications by Satellite, Including Regional Systems (GMPCS-MoU). ETSI TR 101 374-1 V1.2.1 (1998-10) 12 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 3 Abbreviations | For the purposes of the present document, the following abbreviations apply: ACTS (EU) Advanced Communications Technologies and Services ACTS (NASA) Advanced Communications Technology Satellite Program AM Amplitude Modulation ARTES Advanced Research in Telecommunications Systems ATM Asynchronous Transfer Mode ADSL Asymmetric Digital Subscriber Line API Application Programming Interface ATDM Asynchronous TDM BRAN Broadband Radio Access Network BER Bit Error Rate BPSK Binary Phase Shift Keying BSM Broadband Satellite Multimedia CATV Cable Television CCITT Comité Consultatif International des Postes et Télécommunications CDMA Code Division Multiple Access CD-ROM Compact Disc Read-Only Memory CEPT European Conference of Postal and Telecommunications administrations CERP European Committee for Postal Regulation CMF Control and Monitoring Functions CMOS Charge-coupled Metal Oxide Silicon CONUS Continental US CPE Customer Premizes Equipment DAMA Demand Assigned Multiple Access DAVIC Digital Audio Visual Council DBS Direct Broadcast(ing) by Satellite dBW deciBels relative to 1 Watt DECT Digital Enhanced Cordless Telecommunications DTVB Direct TV Broadcasting DSL Digital Subscriber Line DSM-CC Digital Storage Media - Command and Control DSP Digital Signal Processing DVB Digital Video Broadcasting DVB MHP Digital Video Broadcasting - Multimedia Home Platform DVB NIP Digital Video Broadcasting - Network Independent Protocols DVB RC Digital Video Broadcasting - Return Channel DVB RCC Digital Video Broadcasting - Return Channel Cable DVB RT Digital Video Broadcasting - Return Channel Telecommunications (Telephone or ISDN) DVB-S Digital Video Broadcasting - Satellite DVB-SI Digital Video Broadcasting - Service Information Eb/No Energy per bit to Noise density ECTRA European Committee for Telecommunications Regulatory Affairs ECU European Currency Unit EDTV Enhanced Definition Television EHF Extra High Frequency EIRP Equivalent Isotropically Radiated Power E.L. East Latitude EMC Electro-Magnetic Compatibility EN European Standard (harmonized) ERC European Radiocommunications Committee (subgroup of CEPT) ERO European Radiocommunications Office (of ERC) ESA European Space Agency ESTEC European Space Research and Technology Centre (of the ESA) ETO European Telecommunications Office (of ECTRA) ETS European Telecommunications Standard ETSI European Telecommunications Standards Institute EU European Union ETSI TR 101 374-1 V1.2.1 (1998-10) 13 FAA Federal Aviation Administration (US) FEC Forward Error Correction FCC Federal Communications Commission (US) FDMA Frequency Division Multiple Access FM Frequency Modulation F/TDMA Frequency division TDMA FS Fixed Service FSS Fixed Satellite Service GEO Geostationary Earth Orbit GII Global Information Infrastructure GMM Global Multimedia Mobility GMPCS Global Mobile Personal Communications by Satellite GSM Global System for Mobile communication GSO Geo-Stationary Orbit G/T Gain - Temperature Ratio HDTV High Definition Television HEO Highly Elliptical Orbit HFC Hybrid Fibre Coaxial HPA High Power Amplifier ICO Intermediate Circular Orbit IEEE Institute of Electrical and Electronic Engineers (US) IETF Internet Engineering Task Force IF Intermediate Frequency IMT 2000 International Mobile Telecommunications 2000 IN Intelligent Network IP Internet Protocol IPR Intellectual Property Rights ISDN Integrated Services Digital Network ISL Inter Satellite Link ISP Internet Service Provider ITU International Telecommunications Union ITU-R Radiocommunication bureau of ITU K Degrees Kelvin (temperature) kbps Kilobits per second LAN Local Area Network LEO Low Earth Orbit LHCP Left Hand Circular Polarization LMDS Local Multipoint Distribution Service LNB Low Noise Block Mbps Megabits per second MBS Mobile Broadband System MEO Medium Earth Orbit MF-TDMA Multi Frequency TDMA MHP Multimedia Home Platform MIFR Master International Frequency Register (ITU-R) MoU Memorandum of Understanding MPEG Motion Picture Experts Group MPOA Multi-Protocol Over ATM MPLS Multi-Protocol Label Switching MSS Mobile Satellite Service MTSO Mobile Telephone Switching Office N/A Not Available NASA North American Space Agency NASDA National Space Development Agency (Japan) NGSO Non-geostationary Orbit NNI Network to Network Interface OA&M Operation, Administration and Maintenance OBP On Board Processor OQPSK Offset QPSK PA Power Amplifier ETSI TR 101 374-1 V1.2.1 (1998-10) 14 PC Personal Computer PCMCIA Personal Computer Memory Card International Association PCS Personal Communications Service POTS Plain Old Telephone Service PPP Point-to-Point Protocol PSK Phase Shift Keying PSTN Public Switched Telephone Network PTT Posts, Telegraph and Telephone (a licensed common carrier of telecommunications traffic) PVC Permanent Virtual Circuit QPSK Quadrature Phase Shift Keying RAN Radio Access Network RF Radio Frequency RHCP Right Hand Circular Polarization RR Radio Regulation SDH Synchronous Digital Hierarchy SDTV Standard Definition Television SIM Subscriber Identification Module SMATV Satellite Master Antenna Television system SCPC Single Channel Per Carrier SOHO Small Office Home Office SMIT Satellite Master Interactive Terminal S-PCS Satellite Personal Communications Service SSPA Solid State Power Amplifier S-UMTS Satellite component of UMTS TBD To Be Defined TBR Technical Basis for Regulation TCM Trellis Coded Modulation TCP/IP Transmission Control Protocol over Internet Protocol TC-SES Technical Committee - Satellite Earth Stations and Systems (within ETSI) TDM Time Division Multiplex TDMA Time Division Multiple Access TIA Telecommunications Industry Association (US) TNM Telecommunication Network Management TT&C Telemetry, Tracking & Control TV Television TWTA Travelling Wave Tube Amplifier UNI User Network Interface UMTS Universal Mobile Telecommunications System UPU Universal Postal Union URL Universal Resource Locator (Internet) US United States (of America) USB Universal Serial Bus USD US Dollars USAT Ultra Small Aperture Terminal (satellite) VDSL Very High-speed Digital Subscriber Loop VSAT Very Small Aperture Terminal (satellite) WAG Wireless Access Group WARC World Administrative Radio Convention (superseded by WRC) W-ATM Wireless ATM WLAN Wireless LAN WRC World Radiocommunications Conference QAM Quadrature Amplitude Modulation QoS Quality of Service VHS Video Home System WAN Wide Area Network WISDOM Wideband Satellite Demonstrator of Multimedia Services W.L. West Latitude ETSI TR 101 374-1 V1.2.1 (1998-10) 15 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 4 Introduction | The present document has been produced to reflect the growing interest in the development and deployment of Broadband Satellite Multimedia Systems. It is a first-phase report focusing on gathering and presenting information; believed to be valid at the time it was collected. A second phase study, expected to take place in the early part of 1999, will concentrate on a scenario for standardization. An outline is given of present and future systems which provide broadband multimedia services via satellite. Those systems which are already in operation include: ASTRA-NET; EUTELSAT Multimedia Platform; HISPASAT. The Final Acts WRC-97 [1] confirmed previous frequency allocations and allocated new frequencies for such systems at the Ku and Ka-band. The FCC in the United States has awarded several licenses to construct, launch and operate, to qualifying system proponents at the Ka-band. These systems under development are expected to be deployed around years 2001/2003. Within Europe, the Commission of the European Union has highlighted speedy harmonization of technical standards for advanced broadband multimedia satellite terminals and receivers as significant for the prospects of the European industry, operators and users in this area. In order to promote the appropriate technical standardization, a survey of the views of potential players has been conducted; this world-wide request for information has resulted in direct responses from eleven proponents for Broadband Satellite Multimedia Systems: Astrolink, Eutelsat, ICO, Matra Marconi Space, Motorola, SES-ASTRA, SkyBridge, Teledesic, CyberStar, Hispasat, Intelsat, Inmarsat. This information is presented in clause 8 of the present document. In addition, a great deal of information on scenarios, other systems, and research and experimental programmes has been gathered from publicly available sources and is presented as appropriate throughout the present document. The dynamism of the current scenario for Broadband Satellite Multimedia systems and associated technologies is an aspect to consider when producing standards. A common theme from system proponents is that a liberal licensing scheme is seen as a necessary precondition for the commercial success of the envisioned systems, see clause 10. A potential roadmap to this licensing scheme has been established in the framework of S-PCS, where the ERC has produced Decisions, see clause 11. Such Decisions are also needed for Broadband Satellite Multimeda terminals, especially in regard to excemption from individual licenses. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5 Broadband multimedia | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.1 What is broadband multimedia communications? | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.1.1 Multimedia | Multimedia is the combined presentation of several sources of data, most notably text, audio and pictures (moving or still). The definition does not imply any transfer requirements from a distant location, and as such also covers the retrieval of such data from a local storage medium on a computer. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.1.2 Multimedia communications | Multimedia communication is defined as joint transfer and presentation of multimedia data, sound (audio) and picture (moving or still). The definition does not incorporate any real-time requirements. However, real time requirements may be important for the Quality of Service (QoS) of some services. Multimedia services are particularly interesting in connection with Internet applications. ETSI TR 101 374-1 V1.2.1 (1998-10) 16 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.1.3 Broadband multimedia communication | By broadband multimedia, it is meant that the rate of transfer allows "high speed" transfer of multimedia applications and services. The word "broadband" tends to be used in at least two different ways, depending on which community one comes from. In the computer communications world it usually implies a high bit rate, and as such a broadband system could be implemented in a narrower spectrum with a higher order modulation. Thus, the band is seen from the users perspective, and the bandwidth can be interpreted e.g. as a measure of how quickly data can be transferred through a channel. Alternatively, and more generally from the users point of view, how quickly can a service be offered over a channel? In this case the combination of source coding and modulation comes into play for audio and video. The transmission community, on the other hand, interprets bandwidth more physically as a share of the spectrum the (satellite) system operates within. The spectrum is always a limited resource, and is considered of significant importance to use the spectrum efficiently, i.e. that a system should use as little bandwidth as possible to support the services it is designed for. Compression techniques come into play, but definitely also the coding and modulation schemes. Further, the term broad band tends to be subjective. ISDN at 64 kbps in telephone lines is generally not considered to be broadband. In general it does not provide any significant enhancements for voice transmission for the end user either. All he normally gets is plain old telephone quality voice. And nobody would call a computer network with 64 kbps for broadband. Even thin Ethernet has 10 Mbps capacity. However, in a mobile and satellite environment, 64 kbps is sometimes termed both "high speed" and "broad band". Mobile users are generally, and as for the time being, satisfied with having the same services available as fixed users but at a lower rate or poorer quality. However, the mobile users will generally require similar quality as fixed users have, only some years later. For fixed, multimedia satellite users, however, there should be available the same quality as for wired users. This will imply at least VHS-like quality on moving images, requiring around 2 Mbps with MPEG-2 coding. One may therefore make the following interpretations: - multimedia services makes no requirement for a minimum bit rate; - for fixed terminals, broadband multimedia services are likely to require around 2 Mbps or more; - for mobile terminals, broadband services are likely to require around 64 kbps or more with MPEG-4; - for nomadic terminals, the requirement is as for fixed terminals. The definitions of the different types of terminals is not always clear, but the following provides an example of what is meant above: - Fixed terminals are permanently installed, and are not intended to be moved. Parameters, such as log-on frequencies and down-link frequencies and other parameters (like their exact position on earth) can be "hard- coded" during installation, and does not need to be changed by a user. The antenna is permanently installed, possible by a professional. - Nomadic terminals are movable terminal, but only when they are not in use. They will therefore not be subjects to fading as mobile terminals are. But since they can log-on to a system from another place on earth next time, the system and terminal needs to be designed accordingly. This may require home location registers and visitor location registers, but no hand-over procedures are far as terminal movement is concerned. Antenna installation (or self-installation) may here be an issue. - Mobile terminals will or can move during operation (as in GSM). This results in completely different (and unpredictable) fading/blocking characteristics, and may not allow as accurate antenna pointing as fixed or nomadic installations. There are several different types of mobility: A user may be mobile (or at least nomadic) even if the terminal is not. A good example of this is though SIM-card technology. A user may take his or her personal profile an log on to different (fixed) terminals. Different mobile multimedia schemes are outlined in the ETSI GMM Report [4]. ETSI TR 101 374-1 V1.2.1 (1998-10) 17 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.2 Multimedia mobility and nomadic use | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.2.1 Global Multimedia Mobility (GMM) | In October 1996, ETSI published the report "Global Multimedia Mobility, A Standardization Framework for Multimedia Mobility in the Information Society". The report recognizes the, then new, allocations by WRC 1995 of Ka- band spectrum to non-geostationary satellite networks, as well as existing allocations for geostationary satellites, as permitting the development of new systems offering multimedia services. It states "The major attraction of such systems is that they could provide a global, high quality set of services in a mobile environment". The report defines a generalized standardization framework for GMM by identifying four "domains" for standardization: - the terminal equipment domain; - the access network domain; - the core transport network domain; - the application services domain (including content provision). Any ETSI standardization developed for Broadband Satellite Multimedia will fit within this domain structure. A GMM Companion Document is currently in preparation in ETSI. Like the original GMM report, the proposed companion document is intended to provide the ETSI view on a broad range of aspects of critical importance for the future telecommunications business (e.g. fixed-mobile convergence, virtual home environment). |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.2.2 UMTS and S-UMTS | The ITU's work on the IMT 2000 (previously Future Public Land Mobile Telecommunication System (FPLMTS) is aimed at the establishment of advanced global mobile communication services within the frequency bands identified by the World Administrative Radio Convention (WARC 92) at 1 885 to 2 025 MHz and 2 110 to 2 200 MHz. ETSI is defining UMTS as the European third generation system within the IMT 2000 family framework. UMTS standards and ITU Recommendations for FPLMTS will be available before the turn of the century, the system will be introduced around the year 2000, with some services or features possibly implemented earlier in GSM. - Mobility will dominate personal communications in year 2000. - Broadband services will dominate computer communications. - UMTS will have a satellite component. UMTS aims to provide a comprehensive set of services, features and tools which enable services to have the "same look and feel" wherever they are used. UMTS will support multimedia services. All calls will have the potential of becoming multimedia calls and there will be no requirement to signal in advance any requirement for any number of media components. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3 Satellites in multimedia communications | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.1 The target markets | There is an increasing need for high speed communication. Boosted by a convergence between information and entertainment, both business and home users are looking for faster connections to the global information infrastructure. The target markets for broadband services varies for different systems. Most seem to focus on Internet access as the service for the market, and also the home user, since it is estimated that there lies the mass market. But also corporate use, as video-conferencing and wireless (and global) LAN expansion are often mentioned applications. The markets also vary in geographic location, and whether it is urban, suburban or rural areas. Several systems highlight the ability to provide global coverage with the same service for an African farmer as a businessman in New York, but there is no reason to suspect that the former sort of market will provide any strong financial benefit for any global data- ETSI TR 101 374-1 V1.2.1 (1998-10) 18 transport provider. The exception may be for travelling (nomadic) users, like TV-crews and news gathering applications, as a cheaper alternative to the super VSAT systems of today. But, basically, it comes down to urban and suburban markets. In urban areas the strong competitor is ADSL, later optical fibers and terrestrial UMTS. Since users will be concentrated geographically, the cost per user of establishing a broadband service, along with the expected traffic these users will generate, may favour the use of wired solutions in urban areas. However, the HALO and SkyStation projects focus on just these urban areas as prime market targets (but then again these are not satellite systems). GEO satellites in general may focus their downlink capacity to regions where the market is. This focus can also be adaptive, taking into account a changing market or corrections to initial predictions. LEO systems, on the other hand will more or less need to be able to offer the same services world-wide. It has been estimated, the cheaper home terminal will generate a market of tens of million units. The corporate units (terminals) will be far fewer, but may generate more traffic. There are different scenarios for the market for broadband satellite communications. None are certain as of today. Probably the wiser approach is to be flexible, but it seems that if terminals can be made as cheap as 500 to 1000 USD, then the home market will be the mass market, and their requirements will dominate the system design. For home users, the cost of the terminals is just one side of the coin. The other is the price of carrying the data, which need to be as low as terrestrial connections can offer or at least in the same range. In addition to the mass markets, there will definitely be niche markets; at least for terminals, like terminals for nomadic use. Possibly also the GEO and NGSO systems will aim for different markets, services or applications. The Internet is now a spearhead and driving force, with all its associated forms on on-line communications, while modern television is a second factor. There is a trend towards a merge between computers and television, and a large demand for PCs to do what TVs can do; display moving images with high quality while keeping the interactive aspect of computers and Internet. Business users want to make remote and branch operations a more immediate part of the corporate structure, with virtual meetings, instantaneous updating of everyone at the company, and seamless information sharing. TV-like content may well be delivered by GEO satellites, as the delay is not usually critical, while video-conferencing and similar applications will use NGSO connections. According to research completed by Andersen Consulting, it is predicted that by 2002, the total world-wide broadband market for transport services will be worth $65 billion, and 12 percent or $8 billion will go to satellite-based communications. By 2005, the amount spent on satellite communications will reach $16 billion and the total world-wide broadband market for transport services will be worth $98 billion. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.2 Technological issues | There are many technological issues involved in the development of future broadband satellite multimedia systems. These cover areas from TCP/IP and Internet over satellite, ATM over satellite, cheap terminal technology, advanced space and antenna technology, spot-beams, network and networking issues, operator issues, service provider issues, billing mechanisms, network and satellite management and much more. Standardization can benefit technology development, as it can focus research and technology development, and define consistent target for different communities. Therefore, broadly speaking, many of the areas that are currently in focus for R&D, may also be interesting to standardize. The European ACTS programme has ongoing research in several fields, including an Interactive Digital Multimedia Services Domain. This includes work on, for example, MPEG, defining a range of state of the art image and sound coding and multiplexing techniques. This standard has been accepted by bodies like the Digital Video Broadcasting project (DVB), ETSI as the basis for new television broadcasting services and by Digital Audio-Visual Council (DAVIC) as the basis for multimedia services via Telecom, CATV and satellite networks. The NASA ACTS project of the US is focusing on: - ATM, IP, and Other Protocols over Satellites, including Interoperability with Terrestrial Networks; - evaluating Satellite Inclined Orbit Operations; - new Ka-band Technology and Hardware Verification. ETSI TR 101 374-1 V1.2.1 (1998-10) 19 Some of the technological issues involved in broadband multimedia satellite communications can also be seen from what issues and topics a forthcoming IEEE Journal on Selected Areas in Communications lists as topics in this field: - satellite system concepts and architectures; - Ka-band and EHF band technologies; - On-Board Processing (OBP) and Inter-Satellite Link (ISL) routing; - performance analyses and interference issues; - channel modelling and fading countermeasures; - multiple access techniques; - on-board antennas and beamforming techniques; - portable terminals, multimedia and Ka band Direct TV Broadcasting (DTVB) terminals; - V/USAT front-end, IF and baseband sections (design and technology to cost); - interworking and integration with terrestrial networks; - technologies for LEO systems; - satellite multimedia services: technical and economic issues; - standardization issues. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.3 Applications and services | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.3.1 Applications | Broadband satellite communications can and will be used for numerous applications. A first, coarse division, may be into: - broadband Access to the Global Information Infrastrucure (typ. Internet access); - closed, global or regional, broadband communication systems. (typ. LAN expansion). There seem to be no particular dominant application for broadband satellite communication systems, but the Internet is definitely now a driving factor. The Internet enables access to a number of services and applications. However, satellite system are able to offer some benefits over other broadband systems, as: - rapid global deployment; - universal access to services; - coverage of sparsely populated areas; - maritime usage; - infrastructure for developing Countries; - global equality of cost of deployment; - flexibility and adaptivity to changing markets, even on 24-hour basis; - single point of contact for global organizations; - temporary increase in capacity for special events; - back-up infrastructure in any part of the world in case of emergencies; - independent of local and regional censorship. Useful for Embassies and suchlike; ETSI TR 101 374-1 V1.2.1 (1998-10) 20 - secure communications; - suitable for broadcast and multicast services; - ability to support movable / nomadic terminals globally; - ability to support mobile terminals globally; - ability to offer lowest cost for some services. Also of interest are issues focused upon on at the (EU) ACTS Mobile Communication Summit 98: - Technology/System Trials for UMTS/MBS/WLAN/BRAN; - Mobile/Wireless Services and Applications; - Mobile Multimedia; - Network Management, TMN, IN; - Digital Cellular Technology and Planning; - Service Access Procedures and QoS; - Multi-Functional and Multi-Mode Terminals; - Broadband Wireless Local Loop; - Mobile Satellite Systems; - UMTS/MBS/WLAN/BRAN System Design; - Multiple Access Techniques; - Receiver and Transmitter Technology; - Radio over Fiber; - Wireless ATM; - Advanced Antenna Systems; - Spectrum standards aspects; - the role of industrial wireless fora. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.3.2 Services | These services constitute a blend for private and business users. Some typical services for broadband satellite are: - Internet Access and Web browsing; - electronic file transfer; - email and other electronic message services; - SW Distribution services; - direct-to-home video and Video on Demand; - audio on demand. World-wide radio and music distribution; - books on demand. Local publishing and printing; - switched broadcast services and interactive TV; - TV Broadcasting; ETSI TR 101 374-1 V1.2.1 (1998-10) 21 - video-conferencing; - electronic transaction processing (banking etc.); - electronic commerce; - tele-medicine; - distance learning, remote education and corporate training; - satellite news gathering; - wireless LAN and remote location LAN extension; - library services and information data bases; - flexible back-haul service; - hot stand-by (restoration) for a terrestrial infrastructure; - link-up for terrestrial systems. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.3.3 Satellites as LAN inter-connection | When satellites are used for LAN inter-connection, a typical requirement is the ability to offer symmetrical transmission capabilities. A company that wants to extent their LAN to another location, will be able to use satellites between e.g. a location in Europe and the far east. Satellites will then typically be an alternative (or supplement) to terrestrial LAN interconnection, such as Ethernet. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.3.4 Satellites as broadband user access | When satellites are used for broadband user access, as for multimedia Internet applications, typical transmission rate requirements are asymmetric. More data is sent to the user than from the user. In these cases, an uplink with lower capacity, maybe in the order of tens to hundreds of kbps can be acceptable. Downlink rates, on the other hand, must be able to carry video, at a few Mbps, or moving images with HDTV quality, at a few tens of Mbps. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.3.3.5 Satellites for broadband service providers | When considering the service providers, anything from one to hundreds of gateways may be required. Each gateway generally has from one to a few uplink carriers, and from one (broadband) to potentially thousands of (TDMA) downlinks. If the asymmetric users with individual traffic dominate the traffic pattern, then the gateways will in general uplink more traffic than they downlink. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 5.4 Multimedia communication interfaces | There is no, single, multimedia communication interface for non-satellite systems. Elaborating on different high-capacity interfaces is beyond the scope of the present document. However, it is noted that work has been initiated in several fora that addresses the application in the satellite environment of standardized broadband interfaces that have largely been developed thus far for application in terrestrial networks, the objective being to ensure that protocols that are in use in terrestrial systems can smoothly inter-operate with a satellite equipment. Among these efforts is the work to develop ATM protocols for satellite systems. Further study is needed to determine the appropriate way forward for ETSI in this area (phase 2). ETSI TR 101 374-1 V1.2.1 (1998-10) 22 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6 Broadband satellite communications | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.1 Satellites for broadband communication | There are a number of issues relating to the use of satellites for broadband communications. These include the transponder frequencies, licensing, coverage, orbits, number of satellites, network architecture, latency, competitive technologies and enabling and complementary technologies. These sections in this subclause will touch upon some of these, hopefully enabling the reader to as good as possible compare the aspects of the different systems described in the clauses 8 and 9. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.2 Current satellite internet and multimedia services | ETSI is not aware of any current Internet over satellite service provider or system that offers users an integrated satellites solution; the systems rely on broadband delivery over satellite, and a receive-only antenna at the customer premizes. The return link, which then is not usually broadband, is often via terrestrial modems to some central hub, or gateway, which transmits to the satellite. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3 System aspects | Broadband satellite multimedia systems are not homogenous. They vary with respects to numerous issues. Most notably are perhaps: - Frequency bands they operate in. Ku / Ka, and later so-called V and Q (40/50 GHz). Also some at lower frequencies. - Orbits. GEO and LEO. Later also MEO and HEO. Thereby also latency. - Coverage: Global and regional. Land mass or oceans as well. Polar regions. - Bit-rates offered. From a few tens or hundreds of kbps to Gbps. - Availability, and thus power requirements and antenna sizes. - Markets that are targeted. Business / consumer trade-off. - Protocols supported / used. Typically DVB or ATM. Looking at the number of degrees of freedom, it will be important to identify commonalties between the systems with respect to standardization. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1 Satellite orbits alternatives | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.1 Low Earth Orbit (LEO) | LEOs are either circular (or elliptical) orbits less than 2 000 km above the surface of the earth. In communications satellites, LEO satellites are generally found some 700 to 1 400 km above the Earth's surface. Orbit periods vary between 90 to 120 minutes, while the maximum time during which a satellite is above the horizon for an observer on the earth is 20 minutes. The footprint radius of a LEO communications satellite is generally 3 000 to 4 000 km. A global communications system using this type of orbit requires many satellites in different inclined, orbits. When a satellite serving a particular user moves below the local horizon, it needs to be able to hand over the service to another satellite in the constellation. Due to the relatively large movement of a satellite in LEO with respect to an observer on the earth, satellite systems using this type of orbit need to be able to cope with large Doppler shifts. ETSI TR 101 374-1 V1.2.1 (1998-10) 23 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.2 Medium Earth Orbits (MEO) / Intermediate Circular Orbits (ICO) | MEOs are circular orbits at an altitude of around 10 000 km, with an orbit period of around 6 hours. The time during which a MEO satellite is in view for an observer on the earth is in the order of a few hours. A global communications system using this type of orbit, requires a modest number of satellites (around 10 to 20) in 2 to 3 orbital planes to achieve global coverage. Compared to a LEO system, hand-over is less frequent, and propagation delay and free space loss are greater. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.3 Highly Elliptical Orbits (HEO) | HEOs typically have a perigee at about 500 km above the surface of the earth and an apogee as high as 50 000 km. The orbits are inclined at 63,4 degrees in order to provide communications services to locations at high northern latitudes. The particular inclination value is selected in order to avoid rotation of the apses, i.e. the intersection of a line from earth centre to apogee and the earth surface will always occur at a latitude of 63,4 degrees North. Orbit period varies from eight to 24 hours. Free space loss and propagation delay is comparable to that of GEO satellites, but HEO systems need to be able to cope with large Doppler shifts. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.4 Geosynchronous orbit | A geosynchronous orbit is any type of orbit which produces a repeating ground track. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.5 Geostationary Orbit (GEO) | A geostationary orbit is a circular orbit in the equatorial plane with an orbital period equal to that of the Earth. A GEO satellite appears fixed from an observer on Earth. This is achieved with an orbital height of 35 786 km (or an orbital radius of 6,6107 Equatorial Earth Radii). A GEO orbit has small non-zero values for inclination and eccentricity, causing the satellite to trace out a small figure of eight in the sky. The round-trip delay is approximately 250 milliseconds. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.6 Polar orbit | A polar orbit covers both poles, and is inclined at about 90 degrees to the equatorial plane. The orbit is fixed in space, and the Earth rotates underneath, therefore a single satellite can in principle provide coverage to the entire globe (but not at the same time). There would be long periods when such a satellite is out of view of a particular ground station, but it may still be acceptable for a store-and-forward type of communication system (messaging). |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.7 Sun-synchronous orbit | A satellite in a Sun-synchronous or Helio-synchronous orbit sun-synchronous orbit crosses the equator and each latitude at the same time each day. The angle between the orbital plane and Sun remains constant, resulting in consistent light conditions. The orbit is therefore advantageous for an Earth Observation satellite. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.1.8 Groundtrack | The satellite track in orbit, traced on the surface of the Earth is termed the satellite groundtrack. Satellite footprint or coverage circle. There are propositions for multimedia satellites in GEO, MEO and LEO orbits, and at the frequency bands S, Ku, Ka and V. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.2 Frequency bands | The frequency bands are subdivided into different regions, depending on their frequency. The grouping may vary, and there is no exact definition. This subclause aims to illustrate that by a few examples. One commonly seen sub-division of frequency characterization as: ETSI TR 101 374-1 V1.2.1 (1998-10) 24 Table 1: Common designation of communications bands ultra-low (ULF) 3 to 30 Hz extremely low (ELF) 30 to 300 Hz voice frequencies (VF) 300 Hz to 3 kHz very low (VLF) 3 to 30 kHz low (LF) 30 to 300 kHz medium (MF) 300 kHz to 3 MHz high (HF) 3 to 30 MHz very high (VHF) 30 to 300 MHz ultra high (UHF) 300 MHz to 3 GHz super high (SHF) 3 to 30 GHz extremely high (EHF) 30 to 300 GHz The following is an approximate division of the bands and the segments used for satellite communication. Table 2: Common designation of satellite communications bands Segment Name Band Bandwidth Used UHF 200 to 400 MHz 160 kHz L 1,5 to 1,6 GHz 47 MHz S 1,6/4 GHz SHF C 6/4 GHz 800 MHz X 8/7 GHz 500 MHz Ku 14/12 GHz 500 MHz Ka 30/20 GHz 2 500 MHz EHF Q 44/20 GHz 3 500 MHz V 64/59 GHz 5 000 MHz Table 3: More detailed band designations HF-band 1,8 to 30 MHz VHF-band 50 to 146 MHz P-band 0,230 to 1 GHz UHF-band 430 to 1 300 MHz L-band 1,530 to 2,700 GHz S-band 2,700 to 3,500 GHz C-band Downlink: 3,700 to 4,200 GHz C-band Uplink 5,925 to 6,425 GHz X-band Downlink: 7,250 to 7,745 GHz X-band Uplink: 7,900 to 8,395 GHz Ku-band Downlink: (region 1) FSS: 10,700 to 11,700 GHz DBS: 11,700 to 12,500 GHz Telecom: 12,500 to 12,750 GHz Ku-band Uplink: FSS & Telecom: 13,75 to 14,5 GHz DBS: 17,300 to 18,100 GHz Ka-band (one interpretation) 17,7 to 31 GHz V-band 36 to 51,4 GHz ETSI TR 101 374-1 V1.2.1 (1998-10) 25 Table 4: Frequency and Wavelength of the IEEE Radar Band designations Band Designation Nominal Frequency Unit HF 3 to 30 MHz VHF 30 to 300 MHz UHF 300 to 1 000 MHz L 1 to 2 GHz S 2 to 4 GHz C 4 to 8 GHz X 8 to 12 GHz Ku 12 to 18 GHz K 18 to 27 GHz Ka 27 to 40 GHz V 40 to 75 GHz W 75 to 110 GHz millimetre (mm) 110 to 300 GHz micrometre (µm) 300 to 3 000 GHz |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.2.1 L/S/C band | These bands have long been used for satellite communications, and their propagation characteristics are well known. There are little problems with rain fading, and the technology is well developed. A drawback may be that antenna sizes need to be relatively large. Inmarsat communications, as an example, have used the L-band for global satellite communications to the terminals up to now, and the C band for gateway-satellite communications. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.2.2 Ku band | The Ku-band has for some time been used for broadcast purposes. There can be problems with rain fading in very wet regions, but generally the issue is not critical. The technology is well developed and commercialized through the millions of consumer direct-to-home TV-systems around the world. The Ku-band supports several Internet over satellite connections today, and it is expected that the broadband satellite multimedia systems prior to around year 2000 will use the Ku-band for content delivery to the customer. The Ka-band may be used for return links. ASTRA, Eutelsat and SkyBridge are systems that will use the Ku-band. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.2.3 Ka band | As the Ka band has come to be synonymous with multimedia satellite systems, it is discussed to a slightly larger degree than the other bands here. The Ka-band is often meant to span the range from 18 to 31 GHz, albeit the exact definition of the frequency range covered by the Ka-band is seen to include frequencies up to 40 GHz in some contexts. For satellite communication purposes, the Ka-band in any case implies uplinks around 30 GHz and downlinks around 20 GHz. Please refer to the section on ITU for exact allocations. The Ka-band is of interest because there is more bandwidth available at these higher frequencies than at the Ku-band, and lower band. It is therefore possible to accommodate more users, and presumably deliver high bit-rate transmission links at a lower cost (per bit/s) for the end users than at lower frequencies and in addition, smaller antennas can be used. The principal problem, or challenge, with the Ka-band, is its susceptibility to rain; resulting in heavy fading, sometimes in the range of 20 dB. This results in requirements for spare power, both in the terminals and satellite, and power control algorithms in the systems, and terminals are required to operate with as little power as possible so as not to interfere more than necessary with other users. Some systems also include rain-adaptive coding on the downlink, whereas adaptive modulation has not (yet) been observed designed into planned systems. Satellite communications at the Ka-band will involve the development of new technology that is critical to the success of commercial Ka-band systems. In particular is this is the case for satellites and terminals, as the terminals need to be ETSI TR 101 374-1 V1.2.1 (1998-10) 26 relatively cheap to be able to compete with other access methods. Ka-band satellite technology has been demonstrated by DFS Kopernicus, N-Star, Italsat, ESA's Olympus project and NASA's ACTS satellite. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.2.4 V band | The V-band is used to classify the band above the Ka-band that will be used for broadband communications purposes. It will basically imply frequencies in the region 40/50 GHz. ETSI has been able to find few details in propagation characteristics, but obviously the rain attenuation problem is even more pronounced than at the Ka-band. As for technology, there are needs for large amounts of R&D work before components can be commercialized. The V-band can support even larger communications bandwidths than the Ka-band, and with smaller antennas. SkyStation aims to use the V-band, and have had a small portion of the band set aside for stratospheric communication (not satellite). Motorola M-star has filed with the FCC for using the V-band, and this may have lead to more applications for using the band. Currently there are several applications, but not yet any approvals or final allocations. FCC may have been pushed into the V-band applications round following applications from Motorola for its M-Star system. FCC policy states that other players must be given a chance to apply for spectrum on an equal basis before a request can be met. Hughes Communications Inc. and Loral Space & Communications Ltd., have filed for more than one new system, indicating a need to cover all their bases as they try to plan for future services. The following systems have filed for or are filing for V-band spectrum use: - Hughes' Expressway, StarLynx and SpaceCast; - TRW's GESN; - Lockheed Martin/TRW Milstar (in operation); - Loral's CyberPath; - GE Americom's GE*StarPlus; - Orbital Science's Orblink, extensions to Ellipso; - PanAmSat's V-Stream; - Lockheed Martin Q/V-Band System; - Motorola M-Star; - Teledesic; - Spectrum Astro Aster Satellite System. In addition there is the non-satellite: • SkyStation system at 47 GHz. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.3 Interference and coexistence | This subclause identifies some of the important issues relating to spectrum sharing among BSM systems and between BSM systems and systems in other radio services. Following are the sharing situations relevant to BSM systems: - GSO/GSO; - NGSO/NGSO; - GSO/NGSO; - satellite/terrestrial. It should be noted that the implications of the above-identified BSM sharing situations may vary depending on a number of considerations, several of which are: - the direction of the satellite transmission (uplink or downlink); ETSI TR 101 374-1 V1.2.1 (1998-10) 27 - antenna design and operating considerations (capability, cost, installation and control of consumer marketed devices); - use of modulation schemes, access techniques, and/or antenna technology to improve system performance and/or sharing capability; - the type and level of deployment of terrestrial services in certain frequency bands; - band-specific radio regulations or other regulatory policies affecting the implementation and/or operation of a given BSM satellite system(s) in a certain frequency band(s); - band-specific radio regulations or other regulatory policies affecting the implementation and/or operation of terrestrial systems in certain shared frequency bands. As summarized above, there are a number of significant issues to be addressed that impact prospects for sharing between BSM systems and systems in other services, as well as sharing between BSM systems. Due to regulatory uncertainties and a number of other factors, it is difficult to make generalized prioritizations of these issues. It is possible, however, to classify the scope and priority of issues by frequency band. For example, the technical provisions in the portions of the Ku-Band and Ka-Band targeted for possible use by BSM systems that are subject to provisional power limits adopted at WRC-97, are subject to further review at WRC - 2000. A major component of this further review is the verification of the power limits intended to facilitate sharing between NGSO and GSO BSM systems, as well as other satellite and terrestrial systems. In the 18,8 to 19,3 GHz and 28,6 to 29,1 GHz bands, the applicable international regulatory provisions have been fully established. The issues in these bands are focused largely on prospects for sharing with terrestrial fixed service systems. In the V-Band, there appears to be slightly more flexibility in addressing sharing issues. This is due to the fact that only certain portions of the existing co- primary satellite and terrestrial allocations are in use by the terrestrial services, and because V-Band satellite programs are at a relatively early stage of development, as compared to Ku-Band and Ka-Band programs. Several CEPT and ITU-R groups are involved in the study of issues relating to sharing between BSM systems and systems in other services, as well as sharing between BSM systems. These include, but are not necessarily limited to: CEPT project teams PT SE-19, PT SE-16, and PT FM-34; ITU-R Working Party 4A, Joint Working Party 4/9S, and Joint Technical Group 4-9-11. In the United States, work relating to BSM sharing issues is underway in a number of proceedings before the Federal Communications Commission. Additionally, the Telecommunications Industry Association has several technical groups that address BSM-related sharing issues. These include TR-34, TR-41, and joint activities between these two groups. Any work conducted in ETSI should take due account of the work being conducted in these fora. Further consideration should be given to specific approaches to integrating ETSI's BSM work with the work of other technical organizations. It is clear, however, that the work ongoing in CEPT is most relevant to the European environment. This is not meant to discount in any way the importance of the work ongoing in ITU-R or in the United States. The reader is also referred to ETSI's first two draft standards in a family (Ku/Ka & Ka/Ka): EN 301 359 [5] and EN 301 358 [6] both using satellites in geostationary orbit (GEO). Satellite Interactive Terminals (SIT) and Satellite User Terminals (SUT) aim at individual or collective use. SUT are used mainly for transmission and reception of data signals. SIT are used for reception of audio-visual signals as well as data and for providing a return channel for interactive services via satellite. Typically the received signal is digitally modulated as defined in EN 300 421 [7]. The two ENs should protect other users of the frequency spectrum, both satellite and terrestrial, from unacceptable interference. The requirements have been selected to ensure an adequate level of compatibility with other radio services. Both ENs define the minimum specifications of the technical characteristics of SIT/SUT operating as part of a satellite network. The equipment considered comprizes both the outdoor unit, usually composed of the antenna subsystem and associated up-converter, power amplifier and Low Noise Block (LNB) down-converter, and the indoor unit, usually composed of receive and transmit logic as well as the modulator, including cables between these two units. SIT/SUT common characteristics: - transmit through geostationary satellites with spacing down to 2° away from any other geostationary satellite operating in the same frequency band and covering the same area; ETSI TR 101 374-1 V1.2.1 (1998-10) 28 - linear or circular polarization is used for transmission or reception; - received signals may be analogue and/or digital; - transmitted signals are always of digital nature; - antenna diameter does not exceed 1,8 m, or equivalent corresponding aperture; - designed for unattended operations. SIT only characteristics (EN 301 359 [5]): - SIT reception is in the Fixed Satellite Service (FSS) frequency ranges from 10,70 GHz to 11,70 GHz and from 12,50 GHz to 12,75 GHz as well as the Broadcast Satellite Service (BSS) frequency range from 11,70 GHz to 12,50 GHz; - SIT transmission is in the frequency band allocated to FSS on a primary basis from 29,5 GHz to 30,0 GHz; SUT only characteristics (EN 301 358 [6]): - SUT reception is in the frequency band allocated to the Fixed Satellite Service (FSS) on a primary basis from 19,7 GHz to 20,2 GHz; - SUT transmission is in the frequency band allocated to FSS on a primary basis from 29,5 GHz to 30,0 GHz. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.4 Bit Error Rates (BER) | In contrast to most current voice communication satellite systems where users are directly connected today, like the Inmarsat system, the new multimedia systems will have to be able to provide services with significantly lower Bit Error Rates (BER). Typically, the target BER lies in the range between 10E-8 and 10E-10, for achieving acceptable quality in ATM systems. A specific bit error rate will result in a specific cell-loss ration for ATM systems, or in a packet error rate. From a users perspective, that may be the more interesting parameter. However, the two can be related through a formula or table, and from a communications engineers designers point of view the BER is a design criteria. Some questions that may need to be answered may be: - how can these low rates be achieved for all conditions? - if an active power control algorithms is used what limits shall there be? - how shall applications or APIs react if the targets are not met? Are there ground for standardization here? - with what probability shall the target BER conditions be met? - how will the availability affect the use of satellite multimedia systems? |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.5 Delay | Delay is also an quality criterion of the system. Satellite systems can provide communication with different delays, reflected in the variety of systems such as store and forward systems, GEO systems, and LEO systems. Adding to the transmission delay from a satellite in a specific orbit, the protocols and coding schemes that are used will also contribute to the overall source-to-receiver delay. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.6 Availability | Satellite systems can have as high availability as terrestrial, cabled systems if properly designed. However, at the Ka- band, current practical limitation in technology coupled with the diverse weather conditions on the Earth, may lead to different availability in different regions. In contrast, the hot and humid tropical regions. While the colder regions can have their periods of heavy rain, the integrated time a system may become unavailable may not be dominant. ETSI TR 101 374-1 V1.2.1 (1998-10) 29 To operate globally with an equal availability and quality, both satellite and terminals may need to have quite flexible characteristics relating to power and coding/modulation. A problem with current technology for the Ka-band is that the amplifiers are both expensive, and to some extent not available in high powers (more than a few Watts). At the lower frequencies, like the Ku-band, this is not considered that big problem. In addition to rain fading, availability is also affected by blocking. For GEO systems and a FSS this is a stationary situation (as long as a tree or building does not appear in front of a terminal after installation). For NGSO systems, however, some of the viewing angles in the horizon are likely to be blocked in some cases. For NGSO systems, satellite visibility and times when satellite diversity can be applied also plays important roles. The target availability for the planned systems lie in the range from 99,5 % to 99,99 %. With a 99,5 % availability, it implies that it is acceptable that the system is unavailable (with the target BER) more than half an hour a week. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.7 Coverage | Future broadband satellite multimedia systems can be categorized as being either Global or Regional in their coverage domain. There is a difference in coverage also between GEO and non-GEO systems: While the GEO systems can adapt their beams coverage to market regions, and thus not cover oceans and regions that are not economically worth covering, this is not as easy for LEO and MEO systems. As the satellites will have footprints that cover most of the earth, they will to a larger degree provide "real" global coverage. However, even LEO and MEO systems may chose not to cover some regions, thereby saving satellite power, for instance. GEO systems will be able to cover approximately 1/3 of the Earth; thus 3 satellites may be sufficient for a global system. The regions that are still not covered at the polar regions; above 70 to 80 degrees, but generally it is accepted close to 100 % of the market potential can be covered. Non-GEO satellites may have different coverage ability as the orbits inclination vary. Polar orbits can cover the whole Earth, and are thus useful for imagery missions and alike, but a large amount of satellite orbit time is spent over polar regions where little traffic is expected. In practice, therefore, the non-GEO systems will usually provide coverage somewhere between ± 60 to 70 degrees north and south. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.8 Polarization | At the Ka-band, systems will be allowed to use either Linear or Circular polarization, while at the Ku-band, the polarization is typically linear. Circular polarization has some distinct advantages in particular for LEO satellites requiring tracking antennas. It is also useful for countering Faraday rotation. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.9 Rain attenuation | Signal attenuation due to rain is a characteristic of both microwave and satellite transmissions. The level of attenuation is the product of a number of variables. Rain fading is the interference caused by raindrops on electromagnetic signals travelling through the atmosphere. When rain fading occurs, the transmission is weakened by absorption and scattering of the signal by raindrops. Rain fading is a local phenomena. To combat rain fading it is common to design the system with a fade-margin, which is the amount of extra power the system can add to the signal strength to compensate for the possibility of rain attenuation. When the reduction in signal strength due to rain does not surpass the rain fade margin, the fade does not have any noticeable effect on transmission. However, as the increased use of power can disturb other users, it need to be used carefully and under regulations. Rain attenuation increases as the signal frequency increases. This is due to the wavelength of each frequency and the size of the raindrop through which the signal has to pass. Transmissions at lower frequencies have a longer wavelength and are less susceptible to rain attenuation. A 6/4 GHz frequency has a wave-length of approximately 7 cm, and a 14/12 GHz frequency has a wavelength of approximately 2 cm. Any raindrop in the path of either signal which approached half the wavelength in diameter, will cause attenuation. Rain also increases the sky temperature. ETSI TR 101 374-1 V1.2.1 (1998-10) 30 The duration a transmission will be affected by rain attenuation and how deep the attenuation will be is determined by the amount of rainfall. The signal strength can generally be affected for two to three minutes during an average rainfall, and up to 15 minutes for extremely heavy rain periods. Various regions in a satellite coverage area can experience different weather patterns. Also, the antennas in each region are generally pointed at different elevation angles, resulting in differences in the length a signal must pass through rainy conditions. L/S and C-band transmissions are virtually immune to adverse weather conditions. For 6/4 GHz signals to be affected would require rain storms approaching hurricane conditions. At the Ku-band, the strength of the satellite signal may be temporarily reduced under severe rain conditions. To compensate for these potential effects, earth stations located in heavy rain areas are designed with more transmit power. Rain attenuation is considered a fundamental problem with Ka-band communications. Communication links at the Ka- band frequencies can be degraded by rain. To combat the rain fading there is a requirement for much spare power. Much of the NASA ACTS program has been devoted to experiments around rain fading and propagation. The exact amount of spare power required depends upon the target availability, and on the position and climate on earth. A margin of 10 to 15 dB at 30 GHz may be required, but typically the proposed systems plan to use 8 to 10 dB. The requirement for spare power puts tougher requirements on the power amplifiers in the satellite and terminals. For the Gateways, spare power is a lesser problem, but reception of very attenuated signal may be impossible with practical limitations. Over-sizing the antenna is a theoretical solution, but in practice one cannot hope to make Ka-band antennas as large as antennas for lower frequencies. This is due to the strict requirements for plain surfaces on these antennas. Further, antenna wetting may also be a problem So can ice and snow. A solution is to establish a remote site with a separate antenna (Antenna Diversity), and use an alternative antenna when conditions are too bad for the primary one. To avoid obstacles it is also required that the satellites are at a high elevation angle above the horizon. For LEO constellations this influences the number of satellites and orbit altitude, and for GEO systems, as well as some LEO systems depending upon orbit inclination, it influences how far north/south one can communicate. In places such as Southeast Asia or the Caribbean, torrential downpours can lower the level of the incoming Ku-band satellite signal by 20 dB or more; this may severely degrade the quality of the signals or even interrupt reception entirely. The duration of rain outages, however, is usually very short and typically occurs in the afternoons or early evenings rather than during the prime time evening viewing hours. For most Ku-band satellite TV viewers, these service interruptions will only amount to the loss of a few hours of viewing time over the course of any year. From the NASA ACTS experiment, the following conclusion is drawn: A fixed clear sky margin should be in the range of 4 to 5 dB, and more like 15 dB in the up link for moderate and heavy rain zones. To obtain a higher system margin it is desirable to combine the uplink power control technique with the technique that implements the source information rate and FEC code rate. Most of the proposed Ka-band systems will implement 5 to 10 dB typically, and target a user availability for terminals in the order of 99,5 %. As mentioned before, this corresponds to approximately 30 minutes outage each week, but actual availability will depend strongly upon geographical location and local rain characteristic. The major reason for not having higher margins is due to the desire for low-cost power amplifiers. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.3.10 Protocols and transmission formats | Most systems claim to be able to support all major protocols and interfaces (like TCP/IP, UNI, User Network Interface, and NNI, Network to Network Interface), but this can be supported by different underlying satellite transmission (air interface) formats. The broadband satellite multimedia systems coming in the near future often are seen to belong to what can be divided into two different classes: - DVB systems, adding inter-activity and generally asymmetric data services to a broadcasting system. These generally also take advantage of existing Ku-band DBS systems, and an to some degree an existing consumer customer base. - ATM systems, typically found fully at the Ka-band. ETSI TR 101 374-1 V1.2.1 (1998-10) 31 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4 The components involved | This subclause briefly describes some of the major individual components involved in broadband satellites systems. An interesting observation may be that the term terminal and gateway are not as clearly defined any longer as they have been. Very high rate terminals can have the same capacity as a gateway, and one may choose to separate them in instance by the way they are interfaced to the network. The components also play different roles when satellites are switching satellites or bent-pipe satellites. In the latter case, the gateways will typically incorporate some switching mechanism. All systems may therefore not include all types of components. Recognizing the differences and similarities, and the difficulty in defining them precisely, this subclause still uses the terms as headings. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.1 Network components | Network components include components that are used for things like: - log-on; - subscriber verification; and - similar tasks. Functions like satellite control and TT&C form part of the operational satellite network, but are not part of the telecommunications functions. All systems need this function, although it may be partly distributed among different types of HW equipment. This type of equipment and functionality can be very system-dependent, at there seem to be little room for or purpose in aiming for any standardization here. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2 Satellites | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2.1 Satellite stabilization | Most satellites are either spin stabilized or body stabilized. - A spin-stabilized satellite has a cylindrical shape. The satellite is divided into halves, allowing one half to spin while the other half remains pointing at earth. The spinning portion contains the solar panels that absorb energy from the sun, while the lower half contains the communications payload. They are in general less expensive and faster to produce than larger, dual-payload satellites and are also easier to control from the ground. - A three-axis or body-stabilized satellite does not spin but instead appears to be continuously pointed at the same spot on earth. Typically larger than the spin-stabilized satellite, the body-stabilized satellite is box- like in appearance upon launch. When the satellite reaches its final orbital location in space, the spacecraft's solar panels are unfurled to a "wing span" of more 20 to 30 m. The solar panels are designed to support greater power, thereby permitting dual payloads and more transmission power to the ground. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2.2 As switches or bent pipes? | To eliminate the need for an additional round trip delay, several of the proposed broadband systems aim to use switching in the sky, inter-satellite links and routing between satellites. For the Iridium system, this had the consequences that the system in principle could operate in a closed mode with only terminals and no gateways. In principle, only one gateway was required to get connections in and out of the systems. In practice an operation without gateways would be of little use, in particular in broadband communications systems, as most of the content an Internet user would download would have to come from terrestrially connected servers. However, switching in the satellite reduces the round trip delay, which may be important in some applications, particularly for GEO satellites. The SkyBridge system has no switching in the satellite, but then again they are at low earth orbit, and delay is small in any case. Teledesic, and Celestri, plus others, are in contrast planned with switching in the space segment, in spite of the LEO characteristics. There is no doubt that intelligent satellites simplify the ground segment, but ETSI TR 101 374-1 V1.2.1 (1998-10) 32 at the cost of more complex satellites which is in general a higher risk. The satellites are more difficult to repair (if not impossible in some cases) and maintain than a terrestrial infrastructure. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2.3 Onboard processing | A new feature for many of the forthcoming satellite systems is that they have on-board signal processing, OBP, in contrast to the bent-pipe approach of current systems. The first system to implement this technology in a commercial context will be the Iridium system, scheduled to be operational later this year. On-boards DSP processing will detect and regenerate the uplinks signals, and allowing smaller antennas. Several systems also have inter-satellite links and on- board switching, so that few gateways are needed. The onboard processor can be responsible for resource control, channelization, demodulation, and decoding/encoding. Onboard decoding allows the satellite to have greater capacity and the system to allow for smaller user terminals. OBP is also useful for adaptive antenna beam-forming. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2.4 Antennas | New antenna technology in the satellites is a pre-requisite for broadband communication, as it allows the use of spot- beams, and thereby increasing the system capacity significantly. Digital signal processing and beam forming, as well as phased array antennas have contributed to this capability. Spot beams can be created by different technologies, and they can be shaped permanently or be re-configurable. Scanning spot-beams can be used to cover low density regions. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2.5 Inter-Satellite Links (ISL) | Inter-satellite links, connecting satellites in space, are used in switched satellite systems, and combined with switching in the satellite it can offer the system the ability to bypass the terrestrial segment switching and routing. ISLs can be either optical or at radio frequency. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.2.6 Launch | Rocket launch capacity is limited, and there a few sites world-wide that have the capability to launch satellites into orbit. For GEO systems, this may not be a major problem, but for the LEO systems with a large number of satellites the deployment time required to launch all the satellites is a challenge. LEO systems require all or at least many satellites in orbit to operate as a system, and it can therefore take more than a year before the first satellite is launched until the system begins to create revenues. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.3 Gateways | If one considers a large number of consumer terminals, where the users download broadband multimedia, the content has to come from some gateway or high capacity terminal. To achieve a sufficiently high capacity for a large number of users, the broadband systems may need to have a high number of such gateways (or high capacity terminals). Current satellite systems, primary for voice, need not have more than a few gateways world-wide to operate, as the amount of up- and downlink spectrum is not generally a limitation. For broadband systems the bandwidth per gateway/terminal is limited (to 500 MHz or 1 GHz, depending on system). Within this bandwidth, only a limited number of individual multimedia channels can be supported, therefore many such gateways may be required. Since these will serve several users, their availability will also generally be required to be higher than that of an individual (single user) terminal. Antenna diversity may therefore be applied. Since the difference between terminals and gateways tend to diminish, standardization may be equally important and gateways may be considered as multi-user terminals. Broadband satellite systems may therefore choose to use several hundred gateways, as is the case foe SkyBridge. ETSI TR 101 374-1 V1.2.1 (1998-10) 33 |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.4 Terminals | Responses to the Questionnaire indicate that different BSM system proponents have devized different system architectures. Some of these designs entail the use of "gateway" earth stations to pool traffic or act as PSTN interconnect points. Other design architectures do not classify earth stations in this fashion. The issue of satellite terminal classification has also been addressed in numerous regulatory fora, with the results often creating ambiguous or conflicting working definitions that can result in confusion. Developments in operational and regulatory classifications for BSM earth stations have clear implications for ETSI standardization efforts. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.4.1 Low-cost SSPA | For the terminal, that aim to obtain the low pricing, the outdoor unit with the high power amplifier is a most challenging unit for Ka-band systems. Solid State Power Amplifier, SSPA, are required to obtain a reasonable cost, and these struggle to obtain 2 W power today. To obtain more, several have to be combined, and this is not trivial as the number of units to combine increase. A cost-effective alternative in the 2 to 15 W region can be tubes (or vacuum electronic devices). - The EIRP of a terminal may need to be standardized and regulated. - Recommendations for the SAR of a terminal already exist. These may need updating with the Ku/Ka band systems. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.4.2 Antenna and antenna pointing | The antenna subclause also contributes significantly to the terminal price. But more importantly, when the terminals also shall transmit data then antenna pointing becomes a critical issue. A wrongly pointed antenna may first not transmit or receive enough useful power towards the satellite, but more importantly, it may transmit towards a wrong satellite and distort for other users. - Antenna characteristics will need to be standardized and regulated. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.4.4.3 Mobility and nomadic use | Broadband satellite multimedia will typically be used as a fixed satellite service. Currently the Ka band is also only licensed for fixed services. Because of problems associated with antenna pointing, it is not imagined that broadband terminals receiving several Mbps will have the ability to become mobile for some time yet. However, as compression techniques may evolve, the services in question may become available with lower requirements for transmission capacity, and as such may eventually meet technically viable solutions. Nomadic terminals, on the other hand, are fully possible. These depend mostly on a practical way to get the antenna pointing correct, as one can not rely on a professional installation whenever the terminal is moved. With phased array antennas, which today are expensive, but in the 5 to 10 year term may become reasonable, nomadic terminals for a mass- market may be a reality. Nomadic terminals may raise an issue with respect to inter-system roaming. Cruise ships and marine terminals for very stable and slowly moving objects may be considered as a twofold problem. The technical issue is definitely simpler than for land mobile applications, but then again there is the licensing issues that allows the current Ka-band use only for fixed services. - Marine terminals will raise a question relating to beam hand-over. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.5 Communication issues | |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.5.1 Access multiplexing | The most common access format for the broadband satellites systems are to use some form of frequency division TDMA on the uplink, and a TDM structure on the downlink. There has also been responses to ETSI that CDMA will be used. ETSI TR 101 374-1 V1.2.1 (1998-10) 34 Orthogonal Frequency Division Multiple Access (OFDMA) has also been suggested as an access scheme for the return channel of future interactive. - TDMA schemes raise questions relating to synchronization, and up and down power ramping that maybe of interest with respect to synchronization. |
687ea47256d0a0253a548ca8c0b1feaf | 101 374-1 | 6.5.2 Modulation and coding |
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