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681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2 Mobility Management using a Layered Architecture | |
681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2.1 Physical layer and link layer | Both access networks and core networks will have various physical layers and link layers. Diversity in access technologies will occur especially at network edges (wireless, wire-line, Public Switched Telephone Network (PSTN), Asymmetric Digital Subscriber Line (ADSL), etc.). Some of the access networks may have scarce resources, some of them may already have Quality of Service (QoS) access mechanisms (e.g. the PSTN). The intention of a layered architecture is to hide, as much as possible, the various access technologies from the applications running on top. There are instances though where access technology related information needs to be conveyed end to end (e.g. QoS related parameters conveyed at the router level). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2.2 IP network layer and transport layer | One of the more important aspects of VoIP is Quality of Service. IP Quality of Service should be provided independently of the application requesting it. The IP layer might be aware of the fact that the underlying transport mechanism is e.g. a wireless link (possibly due to header compression). IP QoS issues might also be different over a public wireless IP link compared to over a private LAN, but again, as much as possible should be hidden to applications on top of the IP layer. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 14 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2.3 Applications layer | The application layer itself is to some extent layered as well. Some applications may make use of underlying applications. This split within the applications layer depends on the functionality, but still, from an IP perspective, these underlying applications are all applications on top of IP. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2.3.1 Basic conversational voice applications and multimedia applications | Conversational voice applications provide two way speech between users. Non-conversational voice applications provide a means for a user to leave a message to be played back to the intended recipient at some later time, e.g. voice mail. This is the application at the core of the mobility activities in TIPHON. The application can be considered as a separate layer, mainly in cases of interworking with SCNs, where the voice telephony application and voice bearer are tightly coupled and could be considered as THE application. For an IP network, a conversational voice service should be considered as just one of the real-time applications. In principle only the business roles (see [26] and [27]) involved in the application need to be aware of the application. In a pure IP case the business roles involved relate to the two parties involved in the call, and any service provider(s) with whom the communicating parties have a subscription. In case of roaming and Voice over IP registration in a visited network, the business role is also aware of the application. However, a core network just offering IP transport of the voice packets does not have to be aware of the application that is using the network. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2.3.2 Other Applications | Access to an IP network can of course be used for many applications that are not call related, e.g. mail applications, Web-browsing, content on demand. Access to an IP network does not automatically imply that a user wishes to make or receive calls. Another class of applications is non-call related applications that interact with or invoke underlying basic voice and/or multimedia applications (e.g. Web-portals, call centres, personal communication agents). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 4.2.4 Wireless Access and VoIP | In an unbundled IP world, the application is separated from the transport. However, access registration may still be coupled to the application registration. This is not the case for certain wireless access networks such as the General Packet Radio Service (GPRS). The reason being that the initial registration is with the access (GPRS) network for the transport of the application to the IP network and a further registration is then required for the application with the IP network. The reason a user may require wireless IP access may be to be able to read E-mail only and so the user may not want to have the ability to be called or to place calls. Nodes between the terminal application and a telephony server in the network do not have to be aware of the telephony application. This facilitates introduction of new versions of the voice/multimedia application, or parallel operation of alternatives such as Session Initiation Protocol (SIP) [29] and ITU-T Recommendation H.323 [28]. Applications should not be tailored to one type of access so as to make optimal use of the possibilities that multimedia over IP offers. Tailoring applications to one type of access could limit the service offering, which in turn could close the architecture to new and flexible applications. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 15 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5 Roaming technologies | |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.1 Global System for Mobile communications (GSM) | A GSM network can be divided into three broad parts: • the mobile station; • the base station subsystem; and • the network subsystem (Mobile Switching Centre (MSC), Home location register (HLR), Visitor Location Register (VLR), Authentication Centre, and Equipment Identification Register). The mobile station consists of a terminal and a Subscriber Identity Module (SIM) that provides a level of user mobility so that the user can have access to subscribed services regardless of the terminal used. By inserting the SIM card into another GSM terminal, the user is able to receive calls at that terminal, make calls from that terminal, and receive other subscribed services. The usage of SIM card is restricted to one user per card, so a user can not use two different terminals at the same time. The mobile station is uniquely identified by the International Mobile Equipment Identity (IMEI). The SIM card contains the International Mobile Station Identity (IMSI) used to identify the subscriber to the system, a private key for authentication, and other information. The IMEI and the IMSI are independent, thereby allowing personal mobility. Service mobility is provided to the user through Intelligent Network (IN) services (e.g. those specified by ETSI SMG committee: Customized Applications for Mobile Network Enhanced Logic (CAMEL) and supplementary services) within the GSM systems where the end user should not see any difference in the services provided by the IN nodes irrespective of the user's location and the terminal used. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.1.1 GSM location update | The location updating procedures, and subsequent call routing, use the MSC and two location registers: the HLR and the VLR. When a mobile station is switched on in a new location area, or it moves to a new location area or a different operator's Public Land Mobile Network (PLMN), it registers with the network to indicate its current location. In the normal case, a location update message is sent to the new MSC/VLR, which records the location area information, and then sends the location information to the subscriber's HLR. The information sent to the HLR is normally the SS7 address of the new VLR, although it may be a routing number. The reason why a routing number is not normally assigned, even though it would reduce signalling, is that there are only a limited number of routing numbers available in the new MSC/VLR and they are allocated on demand for incoming calls. If the subscriber is entitled to service, the HLR sends a subset of the subscriber information, needed for call control, to the new MSC/VLR, and, if there is a previous registration, the HLR sends a message to the previous MSC/VLR to cancel the previous registration. For reliability reasons, GSM also has a periodic location updating procedure. If an HLR or MSC/VLR fails, and as a result all mobile stations attempt to re-register simultaneously to bring the database up to date, this would cause overloading of the network. Therefore, the database is updated only when location update events occur. The enabling of periodic updating, and the time period between periodic updates, is controlled by the operator, and is a trade-off between signalling traffic and speed of recovery. If a mobile station has not re-registered when the updating time period expires, it is deregistered. The IMSI attach and detach mechanism is related to location updating. An IMSI detach informs the network that the mobile station is unreachable, and avoids allocating channels and sending paging messages unnecessarily. An IMSI attach is similar to a location update, and informs the network that the mobile station is reachable again. The activation of IMSI attach/detach is controlled by the operator and may be on an individual cell basis. The location of a subscriber is uniquely identified by the Location Area Identity (LAI), which is composed of the mobile country code, the mobile network code, and the location area code. The mobile country code is a three-digit value that identifies the country where the network is located. The mobile network code identifies different (competing) networks within a country. The location area code identifies the physical area in which a mobile subscriber is located. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 16 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.1.2 GSM Call Routing | To make a call in a GSM network, the calling party dials the called subscribers Mobile Subscriber ISDN (MSISDN) number which uses ITU-T Recommendation E.164 [1] address scheme. An incoming call is directed to the Gateway MSC (GMSC) function. The GMSC is basically a switch which is able to interrogate the called subscriber's HLR to obtain routing information, and this is achieved by the GMSC mapping the MSISDNs to the called subscriber's HLR. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.1.2.1 Routing within a PLMN | A call terminating on a mobile station is routed through the GMSC to a Visited Mobile Switcheind Centre (VMSC) identified by the HLR, based on the location of the terminating mobile subscriber. The GMSC interrogates the HLR for the routing information of the subscriber. The HLR has the latest location area information, which it uses to request to the appropriate VLR for the temporary roaming number (Mobile Station Roaming Number (MSRN)). The VLR requests the temporary roaming number from the appropriate VMSC. The VMSC randomly selects an available temporary roaming number and this is reported to the VLR. The VLR reports the temporary roaming number to the HLR, which reports the temporary roaming number to the GMSC. Using the temporary roaming number, the call set-up is performed from the GMSC to the VMSC. The VMSC proceeds to page the subscriber in the location area. Upon page response, the call is connected (end-to-end). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.1.2.2 Call routing for an inter-network roaming subscriber | In principle, the call establishment is identical to the scenario of "Routing in the PLMN". Inter-network roaming occurs when a subscriber is registered outside the subscriber's home network. If optimal routing is not supported , the call will be routed to the GMSC in the home network where the routing interrogation begins. The establishment of the call then takes place between the GMSC in the home network and the VMSC in the target network. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.1.2.3 Support of Optimal Routing | Call routing in the original GSM architecture does not always follow the most direct route, particularly in the case of roaming subscribers. The call charges for non optimal routing are quite expensive and the traffic unnecessarily occupies international lines. GSM Phase 2+ intends to implement the support of optimal routing to reduce unnecessary international links. Details on the support of optimal routing can be found in GSM 02.79 [7] and GSM 03.79 [8]. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.2 US cellular system (ANSI-41) | Cellular networks conforming to ANSI TIA/EIA 41 [31] interoperate to provide nation-wide roaming services to mobile subscribers. They also interwork with the PSTN and ISDN to support calls between cellular and wire line parties. Roaming agreements between the cellular service providers in the USA and Canada form the basis for proper routing and signalling information between two networks. They also permit the ANSI-41 signalling communications specified in ANSI TIA/EIA 41 [31] between cellular networks that provides the mobility management and call processing functions. Based on these agreements, configuration tables in the network equipment contain information that enables subscribers to register and receive services from a visited system. Without roaming agreements with a visited system, the visiting mobile may obtain service through a clearinghouse network that has a roaming agreement to the roaming mobile subscriber's home network. NOTE: To properly route a call to/from a roaming mobile, the roaming agreements require technical information (e.g. MSC Numbering Plan Area (NPA), MSC identity, SS7 Message Transfer Part (MTP)/Signalling Connection and Control Part (SCCP) point codes) shared about the cellular networks involved. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 17 For Cellular networks conforming to ANSI TIA/EIA 41 [31] to support international roaming, numbering and international call delivery problems need to be resolved. Mobile Information Numbers (MIN) use the 10-digit subscriber directory number that follows the North American Numbering Plan (NANP). The NANP is a subset of ITU-T Recommendation E.164 [1], the international ISDN numbering plan standard. ITU-T Recommendation E.164 [1] includes a Country Code, a National Destination Code, and a Subscriber Number. Together the National Destination Code and the Subscriber Number comprise the National Significant Number. The 10-digit MIN complies with the international National Significant Number format of ITU-T Recommendation E.164 [1]. Since most of the North American mobile subscribers possess a 10-digit MIN, this causes problems when trying to register an international subscriber in North American networks. The country code of the MIN could be interpreted as part of the NPA and the wrong HLR could be queried for Mobile Subscriber service qualification. Similarly, a North American subscriber roaming internationally would have the first few digits of the MIN interpreted as a Country Code, and thus registration would also be attempted at the wrong HLR. One solution is to expand the existing MIN length to at least 12 digits to accommodate a Country Code. This would enable true seamless automatic roaming using the existing ITU-T Recommendation E.164 [1] format. However, this will require major changes throughout cellular networks conforming to ANSI TIA/EIA 41 [31] to convert all of the 10-digit MINs. Another solution that has been proposed is know as HLR double dipping. That is, when a mobile station registers with a MIN that may be ambiguous, sequential queries are made from the serving network to the two HLRs that both maintain each interpretation of the ambiguous MIN. This solution has drawbacks and causes extraneous signalling traffic. Further research is needed to resolve the numbering problem. Temporary Location Directory Number used for call delivery to a roaming mobile station in networks conforming to ANSI TIA/EIA 41 [31] also adopts a 10-digit format in ANSI-41 Rev. A and ANSI-41 Rev. B. In ANSI-41 Rev. C the Temporary Location Directory Number is explicitly stated to be a maximum of 15 digits in length. If a 10-digit Temporary Location Directory Number is used to deliver a call to a roaming mobile outside of the USA or Canada, the call may not be properly delivered due to the same numbering problem. Networks conforming to ANSI TIA/EIA 41 [31] provide support for different wireless access technologies (e.g. Advanced Mobile Phone Service (AMPS), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Narrowband Advanced Mobile Phone Service (N-AMPS)). Unlike GSM networks, networks conforming to ANSI TIA/EIA 41 [31] are built to offer mainly terminal mobility. The entity associated with the roaming is the terminal. However, roaming is not merely the network simply monitoring of the terminal as it moves. In ANSI-41, the status of the subscriber is also tightly associated with the terminal "roaming" within the network. Mobility Management (MM) is defined by a set of functions, enabling the network to keep track of the user's status and terminal location while the terminal/user is moving in the network. The objective of MM is to enable the network to deliver calls to the subscriber, and to authorize the subscriber for service in a given service area, also known as system. To manage terminal/user mobility, a database record called a service profile is maintained in the network. One service profile is associated with one subscriber (and associated with one terminal). This database record contains both temporary data, such as current location and status of subscriber, as well as permanent data, such as subscribed features. Roaming, also known as Automatic Roaming in ANSI TIA/EIA 41 [31], is a set of network functions that enable the subscriber to receive calls, and use call features while moving throughout the networks. Originating a call may not require roaming, however MM occurs as a consequence of originating a call. Roaming is transparent to the subscriber and moving between systems requires no special actions. The detection of a subscriber/terminal in a new serving network is known as a registration event. The different types of registration events in ANSI TIA/EIA 41 [31] are largely air interface dependent, i.e. AMPS, TDMA, and CDMA all support different types of registrations. Registration may initiate other network processes such as location management, service qualification and user/terminal state management. In ANSI TIA/EIA 41 [31], the location management may be defined as the serving system location update process and the HLR location update processes. The terminal location update process creates or modifies the subscriber's temporary record in a visited system and updates the location information in the subscriber record in the HLR. The terminal location cancellation or de-registration deletes the subscriber's temporary record in a visited system and updates the location information in the subscriber's record in the HLR. In ANSI TIA/EIA 41 [31], service qualification authorizes roaming service capabilities for users and terminals in a serving system. The service profile is a specific set of features and service capabilities (including restrictions) that are associated with the user/terminal. The serving system uses this profile to tailor the services it provides to each individual subscriber. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 18 In ANSI TIA/EIA 41 [31], terminal state management coordinates the call delivery Availability State of the terminal between the serving system and the HLR. A terminal in an active state is available for call delivery. When in an inactive state, the terminal is not available for call delivery, however it may be available to receive short message services. When a call is to be routed to the terminal, the same procedure as in GSM applies, whereby an interrogation will be initiated by the gateway (if the call originates from a PSTN), or from an originating network (if the call originates from just another system conforming to ANSI TIA/EIA 41-D [31]. Upon receiving the location interrogation, the home network would request a temporary routing address (Temporary Location Directory Number) from the VLR where the terminal was last located. The request might trigger the process to locate the terminal before returning the routing address. When the HLR receives the routing address from the visited system, it will send it to the gateway or originating network to set up a call using the new routing address. Service mobility is provided to the user through IN services (e.g. Wireless IN contained in ANSI TIA/EIA 41 [31] and supplementary services) within systems that conform to ANSI TIA/EIA 41 [31]. The end user should not see any difference in the services provided by the IN nodes irrespective of the user's location and terminal used. In ANSI TIA/EIA 41 [31] Rev.C, the basic mobile telecommunication network functions related to automatic roaming are summarize in the following table: Table 1: Use of ANSI-41C Operations for Basic Automatic Roaming Use of ANSI-41C Operations for Basic Automatic Roaming MS service qualification RegistrationNotification, QualificationRequest, QualificationDirective MS location management RegistrationNotification, MSInactive, BulkDeregistration, RegistrationCancellation, UnreliableRoamerDataDirective MS state management RegistrationNotification, MSInactive, BulkDeregistration, RegistrationCancellation, UnreliableRoamerDataDirective, RoutingRequest HLR and VLR fault recovery BulkDeregistration, UnreliableRoamerDataDirective |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3 UMTS - Third Generation Partnership Project (3GPP) | |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.1 UMTS PHASE-1 3GPP Release 99 | The UMTS Phase1 3GPP release 1999 architecture (3G TS 23.101 [32]) consists of two network domains: the Circuit Switched Domain, centred around an MSC, and the Packet Switched Domain, centred around GPRS Support Nodes (GSN). The general architecture for 3GPP release 1999 is shown in figure 2. NOTE: For clarity, a number of interfaces have been left off of this picture. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 19 3G MSC/ VLR NODE B RNC RNC 3G SGSN GGSN HLR Gn MAP MAP Packet data networks PSTN/ISDN NODE B NODE B NODE B NODE B Gs Iucs Iups Iups Iucs Core Network Radio Access Network Figure 2: UMTS Phase1 3GPP'99 The Packet-Switched Domain in the Core Network has 2 main interfaces that involve the use of IP: IuPS, between the Radio Network Control (RNC) and the 3rd Generation Serving Gateway Support Node (SGSN), and Gn, between the 3rd Generation SGSN and the GPRS Gateway Support Node (GGSN). The feasibility of Mobile IP as a means to provide connectivity between fixed and mobile access networks connected to an IP network, are among the issues studied by the 3GPP S WG2 Mobile-IP ad-hoc group. A network conforming to UMTS 22.05 [5] is a network operated by a single network operator and consists of: • UMTS Terrestrial Radio Access Network (UTRAN) access networks; • Wideband CDMA (WCDMA); and/or • Time Division CDMA (TD-CDMA); and • GSM BSS access networks; and • a UMTS core network (defined as an evolved GSM network infrastructure (GSM Network SubSystem (NSS) and GPRS backbone) or any new UMTS core network infrastructures, integrating circuit and packet switched traffic). The scope of UMTS requires parallel existence with the pre-UMTS technologies such as, GSM, DECT etc.. The UMTS objectives relevant to the present document are: • to provide a single integrated system in which the user can access services in an easy to use and uniform manner in all environments; • to provide support of roaming users by enabling users to access services provided by their home environment in the same way even when roaming; and • to be IMT2000 (ITU-T Recommendation Q.1711 [9]) compliant in regards to terminal mobility (roaming). The distribution of functionality between the home environment and serving network for an UMTS system are as follows: • the home environment takes care of user authentication, Universal Subscriber Information Module (USIM) issues, billing and User Profile/VHE management; and • the serving network handles the access and transport. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 20 The following responsibilities can be provided by either the home or the serving network or both: • service control; • QoS negotiation; • mobility management including roaming and automatic establishment of roaming agreements. The interfaces have to be able to support inter-system roaming between systems conforming to different standards, provide unified mobility management from the user's perspective and support 3rd Generation features such as VHE. UMTS requires that a system is able to provide User, Terminal, and Service mobility to the end user. Each USIM will be unique and associated with only one home environment. However, a user can have multiple user profiles which can be activated on a per access basis and simultaneous access by the same user using different profiles will also be possible. For an originating access, a user will choose the profile required. For terminating accesses, the profile selected will be based on the user address indicated by the caller (e.g. International Mobile User Number (IMUN) which will be a diallable number allocated to a UMTS user). In respect to personal mobility, UMTS systems rely on the user having a valid USIM, which can be inserted in any compatible 3rdGeneration terminal, whereas, terminal mobility is achieved through the ability of interacting with the access network. The proposed UMTS system is in line with the GSM development of roaming platform for international roaming. The registration and roaming process requires the serving network to be able to contact the given Home Environment and thus maintain some form of process of determining the Home environment. The serving network provides access to the user and through the roaming broker, is able to interwork with any home environment needed. Any user who wants to use the services of a particular network would register with the network and the network would either directly or indirectly interwork with the home environment. As the serving network will need to know how to route the registration message, several methods such as global title translation table or Internet Domain Name Server (DNS) address request etc. can be used. There is no standardization required to facilitate automatic establishment of roaming relationships because these can be implemented with current standards and procedures. This conclusion is based on the fact that three issues have to be resolved for automatic roaming fulfilment: 1) a contractual relationship; 2) a signalling network to support authentication, incoming call handling, etc.; 3) an accounting and settlement procedure. These components have been addressed within the International roaming platform in GSM. The two types of mobility requirements defined by UMTS are described hereafter. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.1.1 UMTS Call-Unrelated Mobility | REGISTRATION FUNCTIONS: - Location Registration - Terminal notifies the network of making first access to the system and provides it with location information and capabilities and services. - Registration of Additional Subscribers - Terminals that allow multiple subscribers can use this process to notify the network of additional subscriber on a specific terminal and its requested services. REGISTRATION REQUIREMENTS: - Subscriber controlled access - Registration should support the possibility of explicit or predefined actions from the mobile subscriber to choose the desired service. - Access restrictions - The limitation of service selection shall be possible according to subscription and authorization. - Subscriber information - A mobile subscriber must be informed about the availability and restrictions of services in the service environment. This information should be available before registration is made. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 21 - Multiple subscribers - Some types of UMTS terminals should provide services to more than one subscriber simultaneously. - Provision of home services - The subscriber shall be able to register in a serving network for services provided by his home environment. The serving network shall provide the services with the same "touch and feel" regardless of serving network (virtual home environment). ATTACH/DETACH: This process will inform the network of the subscriber being reachable or not. Any signal from a detach subscriber will change status to attach. In the same manner, when the status of a subscriber is unknown to the network for a pre-defined period, the status is changed to detach. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.1.2 UMTS Call-related Mobility | REQUIREMENTS FOR CALL HANDLING: - Route Optimization - Route chosen from originating to terminating party should be independent of the location of the home mobility provider. But for heterogeneous environments that are evolving, new mechanisms may be required in order to recognize an UMTS subscriber. - Transparency - A user should be unaware of mobility aspects such as location updating and handover. VIRTUAL HOME ENVIRONMENT: Virtual Home Environment (VHE) is defined as a system concept for personalized service portability across network boundaries and between terminals. The key requirements of the VHE are to provide a user with: - personalized services; - personalized User Interface (within the capabilities of terminals); - consistent set of services from the user's perspective irrespective of access e.g. (fixed, mobile, cordless etc.); - global service availability when roaming. Roles and components involved in realization of VHE are: - Home Environment; - one or more unique Identifiers; - one User; - one or more terminals (simultaneous activation of terminal providing the same service is not allowed); - one or more Serving Network Operator; - one Subscription; - possibly one or more Value added service providers. The requirements for each component are being specified as part of UMTS ongoing work. The Home Environment is responsible for providing services to the user in a consistent manner. The user may have a number of user profiles which enable her to manage communications according to different situations or needs. A combination of services, profiles and personalization information forms the user's personal service environment or VHE. The Home Environment provides services to the user in a managed way, possibly by collaborating with HE-VASPs, but this is transparent to the user. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 22 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.2 UMTS Packet-Switched Domain Architecture | The Packet-Switched Domain in the Core Network has 2 main interfaces that involve the use of IP: IuPS, between the RNC and the 3G SGSN, and the Gn, between the 3G SGSN and GGSN. The feasibility of Mobile IP as a means to provide connectivity between fixed and mobile access networks, connected to an IP network, are among the issues currently studied by the 3GPP S WG2 Mobile-IP ad-hoc group. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.2.1 The IuPS Interface | The IuPS interface comprises of two separate planes, a control plane and a user plane. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.2.2 The IuPS interface control plane | For transport of RANAP messages over IuPS an SCCP protocol shall be used. The SCCP protocol shall fully comply with ITU-T white book. RANAP protocol shall be designed to use this service according to the ITU-T standard. The IuPS shall be designed so that RANAP is not impacted by alternatives for SCCP message transport on layers below SCCP. The UMTS standard shall allow operators to chose one out of two standardized protocol suites for transport of SCCP messages. - Broadband SS7 stack comprising MTP3b on top of SAAL-NNI. - IETF/Sigtran SCTP protocol suite for MTP3 users with adaptation to SCCP. The protocol suite shall fully comply with the IETF standards developed by the Sigtran working group. No UMTS specific adaptations shall be standardized below the SCCP protocol. R A N A P M T P -3 b C T P ( m o d u le S C C P /M T P 3 u s e rs ) S A A L -N N I IP S C C P Figure 3: RANAP Protocol stack options |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.3 Using GPRS Gn Interface within UMTS | User data is transported from the RNC, across the IuPS, via the3G-SGSN, across the Gn, to the GGSN. A tunnelling protocol is used on top of a common layer 2. This tunnelling protocol corresponds to an evolution of the user plane part of GTP (GPRS Tunnelling Protocol) used in GPRS and carried within UDP/IP. The user data plane in the UMTS core network PS Domain is made up of two tunnels: - a first IP/UDP/GTP tunnel between an RNC and a 3G SGSN on IuPS; - a second IP/UDP/GTP tunnel between a 3G SGSN and a GGSN on Gn. This architecture: - Provides hierarchical mobility; - Allows an RNC to be directly connected on the IP domain backbone; - Ensures that all traffic is routed through 3G-SGSN: this supports the operation of functions such as charging and Lawful Interception; - Allows easy insertion of different underlying transport protocols (or new protocol versions) on Gn and Iu if needed in the future. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 23 The protocol stack is shown in figure 4: RLC MAC L1 GTP-U BSSGP ATM L2 L1 UDP/IP L2 L1 UDP/IP Uu Iu-PS Gn Gi UE RNS 3G-SGSN 3G-GGSN GTP-U GTP-U UDP/IP RLC L1 AAL5 ATM UDP/IP GTP-U MAC AAL5 NOTE: Protocol layers above RLC and GTP-U are for further study. Figure 4: GPRS Gn Interface within UMTS |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.4 Use of Mobile IP within UMTS | "Presently, the work of the Mobile IP ad hoc group is defined by two work items (WI) in 3GPP TSG SA WG2, namely, "Combined GSM and Mobile IP mobility handling in UMTS IP CN" and "GPRS Mobile IP interworking". The WI "Combined GSM and Mobile IP mobility handling in UMTS IP CN" is a feasibility study of using Mobile IP for mobility management within the CN. The WI "GPRS Mobile IP interworking" is to identify how to offer Mobile IP to end-users for R99. The following three steps for achieving GPRS evolution towards Mobile IP are foreseen (3G TR 23.920 [6]): - Step (Stage) 1 represents a minimum configuration for an operator, who wishes to offer the mobile IP service. The current GPRS structure is kept and handles the mobility within the PLMN, while MIP allows user to roam between other systems, such as LAN's, and UMTS without loosing an ongoing session, e.g. TCP. This step is corresponds to the WI "GPRS Mobile IP interworking". - Step (Stage) 2: The SGSN and GGSN can be co-located without any alterations of the interfaces. However, to obtain more efficient routing, the MS could change GGSN/FA, i.e. PDP context and care-of address after an inter SGSN handover if it is not transferring data. MS's which are transferring data during the inter SGSN handover could perform the streamlining after the data transfer is completed, using the old GGSN as anchor during the completion of the data transfer. - Step (Stage) 3 is to let MIP handle also handover during ongoing data transfer. The Gn interface is here only needed for handling roaming customers without support for MIP". The ad-hoc group will present its work in an ETR, which will serve as the basis for the changes needed to support the steps described above. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.3.5 UMTS Open Service Architecture | The UMTS Open Service Architecture defines so-called Service Capability Servers, which provide open interfaces for services/applications (API's to be defined in IDL) towards GSM/UMTS bearers and service mechanisms. Examples of server components are Call Control, Location/Positioning, PLMN Information & Notifications. Each of these server components offers its services via defined open interfaces, and implements these by using GSM/UMTS protocols (e.g. MAP, CAP, WAP). The service mechanisms for UMTS phase 1 are Mobile Execution Environment (MeXE), SIM Application Tool kit (SAT) and CAMEL. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 24 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.4 IMT 2000 | IMT-2000 is an ITU-T draft recommendation (ITU-T Recommendations, Q.1701 [3] and ITU-T Recommendation Q.1711 [9]) to provide telecommunication services to mobile and fixed users via a wireless link, covering a wide range of user sectors (e.g. public, private, business, residential, local loop, etc.), radio technologies and coverage (cellular, satellite, cordless, etc.) and accommodating a wide range of user equipment. Intentionally, IMT-2000 systems shall support global roaming and the Virtual Home Environment (VHE) concept, i.e. the user will be provided with a comprehensive set of services and features which have the same look and feel whether they are used in the home or visited network. However, there are no detail implementation or information flows yet to assess how IMT-2000 systems perform automatic global roaming. Some guidelines and functional models to support global roaming are described in ITU-T Recommendation Q.1701 [3] and ITU-T Recommendation Q.1711 [9]. The Network Capabilities Roaming section in the proposed Capability Set 1 for IMT-2000 is outlined to support: - interoperability and roaming among IMT-2000 family of systems using a single subscription; - ability to supplement mobility management with IN-type service logic; - ability to supplement authentication control with IN-type service logic. This capability does not include generation of authentication parameters. Mobility and global roaming: - Location Management, including automatic update; - User Registration, Update and Cancellation; - Service Monitoring Registration, Update, Activation, Deactivation and Cancellation; - User Profile Database management and control; - Security and Authentication Database management and control. Concept and requirements for mobility and roaming. An IMT-2000 System can be described by a set of functional subsystems which perform actions and interact among themselves to support IMT-2000 wireless users. An IMT-2000 System consists of the following functional subsystems: User Identity Module (UIM), Mobile Terminal (MT), Radio Access Network (RAN) and Core Network (CN). IMT2000 is characterized by its concept of family and family members used to realize a global service offering among IMT-2000 systems. The UIM, MT, RAN, and CN functional subsystems may be specific to each Family Member along with the associated internal processes, internal interactions, and internal communication between functional entities. Support for IMT-2000 capabilities and interfaces will facilitate roaming between family members. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.4.1 IMT 2000 Global roaming | An essential service requirement of IMT-2000 is that IMT-2000 users should be able to use their equipment and subscriptions in different family member networks, and to establish calls and connections between networks of different operators. To support this service requirement, interconnection between different IMT-2000 family member networks is required. An IMT-2000 network should therefore be able to interwork with a wide range of existing and future partner networks and services such as other mobile networks, Internet, ISDN, B-ISDN, PSTN, UPT, PDN, GII, etc. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 25 IMT2000 specifies that the network to network interface (NNI) be supported between the following networks: a) Home network is the IMT-2000 network which is related by subscription to the IMT-2000 User. It permanently holds location and service profile information related to the IMT-2000 User. b) Supporting network is the network which provides support for a variety of services including but not limited to service logic programs and service related data for IN supplementary services provided to IMT-2000 Users. c) Visited (Serving) network is the IMT-2000 network where an active IMT-2000 User is being served. d) Interrogating network is the network from which a routing data retrieval request is sent to the Home network of the called IMT-2000 User. e) Destination network is the network to which an outgoing call from an IMT-2000 User is destined. f) Previously visited network is the network where an IMT-2000 user has been served before entering the Visited/(Serving) network. Between IMT-2000 networks, user profile data and location (routing) data is separated from normal call control. This supports the mobility aspect. For this, the following operations of transfer and retrieval of user data and location data would have to be supported by the visited, home, previously visited networks. Location registration/updating, transfer or retrieval of trigger/ service profile data, Retrieval of location and user data, Updating of user data, Location and user data cancellation and Call routing/terminating which could be performed with or without the MSRN number as specified in GSM. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.4.2 IMT-2000 Virtual Home Environment | The VHE is a capability whereby a User is offered the same service experience in a visited network as in his Home system. This would allow users to enjoy Internet style flexibility and operators to differentiate services. The degree to which the VHE matches the actual home environment may be subject to, for example, the degree of co-operation between the visited network and home or supporting networks their relative technical capabilities and the compatibility of the user terminal. The specifications for VHE exist at the requirements level. VHE requires that: 1) the user profile data belongs to user; it can be stored in USIM and/or home database; 2) this profile data can control/run software in mobile station or terminal, serving network or home network (e.g. IN server); 3) this software may already exist or may need to be created and/or delivered to appropriate location; 4) software code and/or data may be needed at more than one node for a given service. Two possible scenarios for VHE are: the Direct-home command and the relay service control. These scenarios are described in ITU-T Recommendation Q.1711 [9]. The service may be executed, based on the program and data in one or more of those entities. The control data could be transported across interfaces such as IP, GPRS, X.25, SMS, SS7. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.5 Universal Personal Telecommunication (UPT) | UPT is a personal mobility telecommunications service wherein a subscriber/user can register at a terminal on any connected network and be provided with UPT service at that terminal location. UPT enables access to telecommunication services while allowing personal mobility. It enables each UPT user to participate in a User-defined set of subscribed services and to initiate and receive calls on the basis of a personal, network-transparent UPT Number across multiple networks at any terminal, fixed or mobile, irrespective of geographic location, limited only by terminal and network capabilities and restrictions imposed by the network operator. Basically, the fixed association between terminal and user identification is removed. Consequently, the identification of UPT Users is treated separately from the addressing of terminals and network access points. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 26 When a UPT user is invoking the service on a particular access, his service profile must apply there and replace the features attached to the subscription of the owner of the terminal. This requirement applies to any action of the UPT user as outgoing call, incoming call, registration or service profile management. The handling of a UPT call implies that the involved exchanges have the knowledge of the UPT characteristics of this call. UPT architecture is derived from the standard architecture by assembling the IN architecture for the originating, terminating and home networks. UPT is provided by a set of procedures that are classified into three different categories. The categories related to mobility and roaming is: 1) Personal mobility procedures Personal mobility procedures are UPT procedures relating to the personal mobility of the UPT user and require access, identification and authentication procedures to be carried out with or before these procedures. Personal mobility procedures are registration procedures used to specify where to receive or make calls and do not include the actual receiving or making of calls. 2) UPT call handling procedures UPT call handling procedures are procedures relating to the actual receiving and making of calls and may require access, identification and authentication procedures to be carried out with or before these procedures. 3) UPT service profile management procedures UPT service profile management procedures allow the UPT user to manage accessible data in their own personal service profile, and require access, identification and authentication procedures to be carried out before or as part of these procedures. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.6 Cellular Digital Packet (CDPD) | Cellular Digital Packet Data or CDPD uses existing cellular network infrastructure and frequency channels, enabling digital AMPS (D-AMPS) and AMPS wireless network operators to offer packet data services for wireless Internet and corporate database access applications. The following list represents the functional components within a CDPD network: - M-ES: the Mobile End System to gain access to CDPD network; - MDBS: the Mobile Data Base Station providing radio link; - DIS: the Mobile Data Intermediate System providing mobility management, registration and forward and redirect data to M-Ess; - S: the Intermediate System that routes data between different components; - ES: the Fixed End System representing traditional external data application and value added network service application systems. CDPD system provides an extension to the existing AMPS and data communications system allowing users to use traditional voice services from the wireless system and at the same time get access to the data applications outside and within the CDPD network (such as SMS delivery, Web browsing). CDPD system does not make use of or connect to the traditional MSCs of the ANSI-41 system. As such, the system has its own set of mobility management and roaming operations independent of the ANSI system. CDPD mobility management is based on same principles as mobile IP. The MD-IS is the central element in the process. A MD-IS is logically separated into a home MD-IS and a serving MD-IS. There is often several serving MD-ISs in a network, all connected to a home MD-IS. A serving MD-IS manages one serving area. The MD-BSs that provides coverage in this area is connected to the serving MD-IS, which has a database containing information about all subscribers currently visiting the area. A home MD-IS contains a subscription database for its geographical area. Each subscriber is registered in the home MD-IS associated with his home area. The IP address of a subscriber points to his home MD-IS. The database keeps information on which serving area a subscriber is currently visiting. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 27 Mobility management in a CDPD network involves maintaining location information database and routing of Network Protocol Data Units (NPDU) based on this information. This information is managed and constrained within the MD-ISs so that routing and relaying is transparent to all other external and internal systems from the CDPD network point of view. Mobility is supported in both Data link layer and Network layer. MD-ES is logically member of a fixed home area that provides mobility-independent routing destination area for ISs and ESs that are not mobile aware. CDPD mobility provides rerouting and forwarding messages from home to the current location of the M-ES. Cell selection procedure allows the M-ES to discover, select and maintain the most optimal channel available in the serving system. Location updating procedure between the M-ES and serving MD-IS results in authenticating and updating the Location directory in the home MD-IS and updating the Registration directory in the serving MD-IS. Redirection and forwarding delivers messages that are destined for M-ESs that are located in a serving MD-IS area by the process of home MD-IS redirecting the messages by forwarding them to the serving MD-IS. Serving MD-IS completes the delivery by routing the message to the M-ES in its current location. The M-ES must be switched on before an end-user can send any data. The M-ES switch-on action sends a message to the serving MD-IS, identifying the user and his home MD-IS. User access rights and authentication processes are performed at the home MD-IS. The IP packets are assembled in the serving MD-IS using the link layer frames received from the MDBS. From the serving MD-IS the IP packets are routed to their destinations. An incoming IP packet is routed to the home MD-IS of the receiver. After finding out in which serving area the subscriber is currently located, the IP packet is tunnelled to the corresponding serving MD-IS. This MD-IS checks in which channel stream the subscriber is active and forwards the packet to the mobile data base station responsible for that channel stream. CDPD has support for sleep mode (inactive). Packets are stored in the serving MD-IS in case a mobile end system is sleeping. If the system (except for sleep mode) is out of contact with mobile end systems, packets are only stored for the time it takes to perform the predetermined number of retransmissions. Then they are discarded. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.7 General Packet Radio Service (GPRS) | General Packet Radio Service (GPRS) provides end-to-end packet data access for the subscriber within GSM systems and towards the PDNs without using circuit switched mode. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.7.1 GSM/GPRS | The GSM/GPRS network infrastructure is obtained from the existing GSM infrastructure by adding two new network elements, the Serving GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN). GPRS defines the concept of Routing Area (RA), defined as a set of radio cells where an idle MS doesn't need to update its location with the network. One or more cells form a RA, which is a subset of the cell in one GSM Location Area (LA). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.7.1.1 GPRS Mobility Elements: SGSN, GGSN, VLR and HLR | An SGSN (Serving GPRS Supporting Node) provides mobility management, register functions such as subscription information (e.g. the IMSI and temporary identities) and location information (e.g. the cell or the RA where the MS is registered, the VLR number of the associated VLR, the GGSN address of the GGSN corresponding to an active PDP context, zero or more PDP addresses). The SGSN is connected to the BSC and is the service access point to the GPRS network for the GPRS MS. An SGSN can support several RAs and can support one or several BSCs. Each routing area is served by one and only one SGSN. The GSM MSC/VLR area (Location Area) and the SGSN area need not have any relationship. GGSN (Gateway GPRS Supporting Node) is the access point from the IP network into the GPRS system. The GGSN stores subscription information (IMSI and zero or more PDP addresses) and routing information (SGSN address needed to deliver packets towards the MS registered in the SGSN) for each subscriber that has at least one Packet Data Protocol (PDP) context active with the GGSN. At the GGSN level, user mobility is tracked with a precision of SGSN. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 28 The VLR (Visited Location Register) that supports both GSM and GPRS needs to provide, in addition to the circuit switched GSM functionality, GPRS function such as storing the identity of the SGSN where the mobile is registered. VLR doesn't provide any register/location management function for the GPRS part of the GSM/GPRS network. HLR (Home Location Register) provides register function for the permanent subscription information and stores the identity of the SGSN where the mobile is registered. GSM HLR is enhanced with GPRS subscriber information. The following identifiers are defined in GPRS: user: IMSI (International Mobile Subscriber Number): it is the same subscriber identifier adopted in GSM. terminal: IMEI (International Mobile Equipment Identity): it is the same terminal identifier adopted in GSM. application: no specific application level identifiers are defined in GPRS. An MS can be assigned one or more logical names (like IP addresses or context identifiers), but the association between the subscriber and the logical name is outside the scope of the GPRS specification. location-identifiers: CellID identifies the cell where the MS is camping. CellID is meaningful only when the MS is actively involved in a connection. RAI (Routing Area Identifier) identifies the RA where the MS is attached to the GPRS network. RAI is used by the MS to determine that a RA update is needed and to indicate to the network its location. temporary-identity: P-TMSI (Packet Temporary Mobile Subscriber Identity): a GPRS IMSI is allocated a temporary P-TMSI when the MS attaches to the network, and a new P-TMSI can be reallocated when the MS changes RA. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.7.1.2 GPRS Registration and Context Activation Procedures | For a MS to access GPRS services, the MS needs first to make its presence known to the network by performing a GPRS Attach to the SGSN. The Attach procedure includes updating the location information in the HLR (if the MS is registering with a new SGSN), transferring information between the old SGSN where the MS was previously attached and the new SGSN, and cancellation of the MS data from the old SGSN (and old VLR if MS was attached also for circuit switched services with the GSM network). In order to transmit or receive data, an MS needs to activate PDP contexts. Activation of PDP context makes the MS known to the GGSN corresponding to the PDP context, and allows packet data transfer to/from the corresponding user. A PDP context contains mapping and routing information for transferring Packet Data Units (PDU) for that particular PDP address between MS and GGSN and vice versa. For each PDP context, the MS is provided with either a static PDP address (includes ETSI X.121 or IETF IPv4 or IPv6 address among other data) assigned at subscription time or a dynamic address, allocated at the PDP context activation by the GGSN of either the HPLMN or VPLMN operator. Dynamic addresses allow only MS-initiated data transfers. Mobile-terminated point-to-point communications ("calls") are delivered to the MS in the following way: - packets are delivered to the GGSN corresponding to the PDP address; - GGSN verifies if the address (e.g. IP address) is active. If it is, the GGSN retrieves the PDP context corresponding the PDP address and the SGSN address of the SGSN where the MS is registered; - GGSN forwards the data to the SGSN serving the MS using the GPRS Tunnelling Protocol (GTP), i.e. encapsulating and tunnelling the received packets to the SGSN with an appropriate Tunnel Identifier (TID) built from the PDP context information; - SGSN received and decapsulates the packets and, from TID, retrieves the information regarding the MS; - SGSN delivers the packets to the MS. If the GGSN determines that the PDP address is inactive, the data is discarded. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 29 For mobile-terminated point-to-point communications, if packets are received by the GGSN before a PDP context has been established by the MS, the GGSN may initiate (when allowed) a network requested PDP context activation procedure (valid for static address only). At GPRS detach, all PDP contexts are implicitly deactivated for the MS. Network (HLR and SGSN) or MS can request an explicit detach. Detach can occur implicitly due to time expiration during the period when there has been no activity by the MS. VLR is notified of the detach procedure so that SGSN association or IMSI related detach information can be managed. For roaming subscribers that have a PDP address allocated from the HPLMN, a forwarding route between the HPLMN and the VPLMN is created for communication to and from the MS. Protocols such as BGP (IETF RFC 1771 [4]) and other routing protocols can be used between the BGs (Border Gateway) based on bilateral agreements between operators. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.7.1.3 GPRS Mobility Management | GPRS provides indication of reachability both to the MS and to the network. MS knows its location both in terms of cell and RA, whereas in the network the MS location is tracked at two levels, depending on the present mobility management state of the Mobile Station (MS). When the MS is in STANDBY, i.e. the MS is attached to the GPRS network for mobility management but is not involved in any active connection, the location is tracked at the Routing Area level. When the user is READY, i.e. it is involved in active connection, the location is tracked at the cell level (i.e. the cell where the MS is camping at present). Mobility between SGSN and GGSN is supported through the adoption of the GPRS Tunnelling Protocol (GTP). GTP allows also transfer of subscriber information and user data between SGSNs when the MS is changing SGSN. In order to maintain its location updated with the network, the MS performs mobility management procedures when it has entered a new cell or a new RA, and periodically depending on network settings (periodic RA updates). A cell update (re-selection) takes place when the MS enters a new cell inside the current RA and the MS is in READY state. If the RA has changed, a RA update is executed instead of a cell update. RA update takes place also when the MS in STANBY state detects that it has entered a new RA, or when the periodic RA update timer has expired. RA update may involve a change of SGSN (inter-SGSN RA update): in this case, the procedure triggers the SGSN to initiate a RA update procedure involving: - the old SGSN, to transfer the PDP context information regarding the active PDP contexts and to setup a forwarding path for data still in transit from the GGSN to the old SGSN; - the GGSN corresponding to each active PDP context, to update the GTP tunnels; - the HLR, in order to store the new SGSN information and to remove the old SGSN and information from it. For transport of real-time services (e.g. voice) over GPRS, a critical element is the RA update. It has to be verified if such procedure can be fast enough to allow MS mobility without disruption in the service. In fact, in GPRS the concept of handover is implemented in terms of cell re-selection and RA update. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.7.1.4 GPRS Analysis and Comments | GPRS mobility management protocols are stable. Improvements are being made to adapt GPRS protocol to 3G systems (e.g. UMTS). GPRS does not allow QoS re-negotiation during mobility. QoS is negotiated at PDP context activation, but nor renegotiated at cell update/RA update. If QoS has to be modified, SGSN can modify it after Cell Update/RA Update has taken place. The concept of Codec re-negotiation does not apply to GPRS. GPRS does not support security re-negotiation during mobility. The MS can anyway be re-authenticated during the RA update, however. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 30 GPRS does not support routing optimization when using a PDP context from HPLMN. As an example, a forwarding route between the HPLMN (Home PLMN) and the VPLMN (Visited PLMN) is created for communication to and from the MS for roaming subscribers that have a static IP PDP addresses allocated from the HPLMN. Protocols such as BGP (IETF RFC 1771 [4]) and other routing protocols can be used between the Border Gateways based on bilateral agreements between operators. GPRS supports service portability between GPRS network, since when the MS roams to a VPLMN the MS service profile is downloaded to the SGSN in the VPLMN where the user is registering. Table 2: GPRS mobility Criteria GPRS User IMSI Terminal IMEI Application PDP Address Identities recognized Location identity RAI, CellID Stability of protocols Stable Critical protocol elements MS, SGSN, GGSN, HLR (VLR) Handover capability Yes Mobility elements involved in handover phase MS, SGSN (VLR) Mechanism to reach the terminal Reachability status flags QoS Codec Security Resource (re-) negotiation capability Other Routing optimization Service portability |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.8 ANSI (IS-136)/GPRS | GPRS architecture has been adapted to work with ANSI-41 system. New additional specifications have been defined in order to interwork GPRS with ANSI-41, but no modifications have been made that may impact GSM GPRS specifications. From the point of view of GPRS mobility management, no differences with GSM GPRS have been introduced, and the same comments reported in the previous subclause are still valid. The following differences are made within the core network functions relevant to mobility management and roaming. (Note that additional changes have been made towards the air interface, other interfaces such as Gs´ and mobile terminals have changed specifications too.) SGSN is also responsible for tunnelling the ANSI-41 related control messages for authentication, location updates, registration etc. SGSN routes packets within the service area it is defined to serve. Both ANSI-41 HLR/AC and GPRS part of GSM HLR is needed in order to support GPRS in ANSI-41 system. The HLR/AC for ANSI-41 requires modifications to handle the GPRS related system access by the MS. The Serving ANSI-41 MSC/VLR serves existing circuit switched based information as defined within ANSI-41. The Gateway ANSI-41 MSC/VLR integrates circuit switched and packet functions within GPRS-136 network by providing circuit switched call routing, redirections, supplementary service interactions and paging and registration handling towards ANSI-41 HLR/AC and provides MIN to IMSI mapping. Provides VLR functions when the serving node is a GPRS SGSN by enabling gateway functions to/from GPRS networks. The Message Centre (MC) is able to receive and accept requests to deliver teleservice messages over the GPRS-136 network and ANSI-41 (136) network. The mobility management for GPRS (as defined in the GSM GPRS SGSN function) and for IS-136 system is kept separately, meaning there is an additional GSM HLR required. An IS-136 registration is handled within ANSI-41 HLR whereas GSM HLR handles GPRS registration. Call delivery from circuit switched network is always handled by the ANSI-41 HLR towards the MSC/VLR. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 31 Serving ANSI-41 MSC/VLR sends the necessary page request towards the SGSN for call delivery when the MS is camped on PCCH (GPRS attach has been performed). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.9 Mobility and roaming in datacom networks | |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.9.1 Mobile IPv4 | Mobile IPv4 - referred to as Mobile IP - allows terminals to roam freely to other networks while still maintaining the same IP address IETF RFC 2004 [17]. Mobile IP consists of three components: mobile node, home agent and a foreign agent, latter two being basically routers with some special functionality. A home agent allows mobile nodes to roam to other networks. A foreign agent allows mobile nodes from other networks to visit to the network. A host exchanging messages with a mobile node is called correspondent node. It may be an ordinary stationary Internet host, or an another mobile node. Mobile IP allows mobile nodes to effectively utilize two IP addresses, one for identification (home address) and one for routing (care-of address). There are two types of care-of addresses in Mobile IP: co-located and foreign agent care-of address. The co-located care-of address represents an address temporarily assigned to the mobile node itself from a PPP or DHCP server. The foreign agent care-of address is the address of the foreign agent with which the mobile node is registered. The mobile node will indicate its preference for a foreign or co-located care-of address in the Mobile IP registration procedures. As using a co-located care-of address wastes scarce resource, namely an IPv4 address, foreign care-of address is assumed for the rest of this subclause. The mobile node uses agent discovery protocol to locate a foreign agent that is willing to provide mobility support to the mobile node. The foreign and home agents periodically multicasts/broadcasts agent advertisement messages, and a mobile node can ask for an agent advertisement message by sending an agent solicitation message. The mobile host can discover the foreign agent identity and the care-of address upon receiving an advertisement message. Once a foreign agent is discovered, the mobile node registers its care-of address along with the registration lifetime to the home agent via foreign agent. The home agent processes the registration by updating its routing table; creates or modifies its mobility binding, associating the mobile host's home address with its current care-of address for the specified registration lifetime. The mobile node identification is currently based on its home address. The Mobile IP working group is working on more generic solution, where a NAI is used for identification purposes. Using NAI is necessary for the home agent to dynamically assign an address to the mobile node, or to use private IP addresses for mobile nodes. When the datagrams sent by a correspondent node arrive to the home network, the home agent redirects them to the care-of address by using an encapsulation method, also known as tunnelling IETF RFC 1701 [18]. It uses the care-of address as the destination address in the new IP header. The new packets are then tunnelled from the home agent to the care-of address indicated in the new IP header, bypassing the usual effect of IP routing. The foreign agent where the tunnel terminates decapsulates the received packet and sends the original packet from the correspondent node to the mobile node. In the reverse direction, a mobile node usually sends its packets through a router on the foreign network and assumes that routing is independent of source address. Reverse tunnelling could be used to allow a mobile node's care-of address to shuttle packets towards the home agent using a symmetric topologically correct reverse tunnel. The tunnel starts from the mobile node's care-of address and terminates at the home agent. An extension providing optimized routing (see Internet Draft mobileip-optim) using routing bindings similar to Mobile IPv6 is still work in progress (July 1999). ETSI ETSI TR 101 338 V1.1.6 (2000-07) 32 Table 3: Mobile IP (V4) mobility Criteria Mobile IP (v4) User NAI, Home IP Address Terminal MAC Address Application Identities recognized Location identity Care-of address Stability of protocols Proposed Internet standard, extensions in Internet drafts Critical protocol elements Mobile node, home agent, foreign agent Handover capability Mobility elements involved in handover phase Mechanism to reach the terminal Sending datagram Reachability status flags ICMP messages may be sent if node is not reachable QoS RSVP Codec Not applicable Security IP Sec Resource (re-) negotiation capability Other Routing optimization Optional, requires support from correspondent node Service portability Not applicable |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.9.2 Mobile IPv6 | IPv6 packets addressed to a mobile node's home address are transparently routed to its care-of address. The protocol enables IPv6 nodes to cache the binding of a mobile node's home address with its care-of address and to then send any packets destined for the mobile node directly to it at this care-of address. IPv6 mobile nodes would have additional capabilities such as support of tunnelling protocol and neighbour discovery. A mobile node typically acquires its care-of address through stateless or stateful (such as DHCPv6, Dynamic Host Configuration Protocol for IPv6) address auto configuration, according to the method of IPv6 neighbour discovery. While away from home, the mobile node registers one of its bindings with a router on its home link, requesting this router to function as the "home agent" for the mobile node. This binding registration is done by the mobile node sending a packet with a "BindingUpdate" destination option to the home agent. The home agent then replies by returning a packet containing a "Binding Acknowledgement" option to the mobile node. The mobile node's home agent thereafter uses proxy neighbour discovery to intercept any IPv6 packets addressed to the mobile node's home address on the home link and tunnels each intercepted packet to the mobile node's primary care-of address. To tunnel each intercepted packet, the home agent encapsulates the packet using IPv6 encapsulation, with the outer IPv6 header addressed to the mobile node's care-of address. When sending a packet to an IPv6 destination, a correspondent node checks its cached bindings for an entry for the packet's destination address. If an entry exists, the host would use IPv6 routing header instead of IPv6 encapsulation to route the packet to the mobile node by way of the care-of address indicated in this binding. Consequently, the home agent is not involved with the packet transmission to the mobile node and optimal routing from the correspondent node to the mobile node is achieved. If the sending node does not have a cached binding for the destination address, the node sends the packet normally which is then intercepted and tunnelled by the mobile node's home agent to the mobile node. When a mobile node receives a packet tunnelled to it from its home agent, the mobile node assumes that the original sending correspondent node has no binding cache entry for the mobile node, otherwise the correspondent node would otherwise have sent the packet directly to the mobile node using routing header. The mobile node thus returns a binding update to the correspondent node, allowing it to cache the mobile node's binding for routing future packets. A correspondent node with a binding cache entry for a mobile node may refresh this binding if it is actively communicating with the mobile node (e.g. it has an open TCP connection), for example if the binding's lifetime is near expiration, by sending a binding request to the mobile node. When a mobile node receives a binding request, it replies with a binding update. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 33 Table 4: Mobile IP (V6) mobility Criteria Mobile IPv6 User NAI, Home IP Address Terminal MAC Address Application Identities recognized Location identity Care-of address Stability of protocols Internet draft Critical protocol elements Mobile node, home agent, correspondent node Handover capability Yes Mobility elements involved in handover phase Mobile node, correspondent node Mechanism to reach the terminal Sending datagram Reachability status flags ICMP messages may be sent if node is not reachable QoS RSVP Codec Not applicable Security IP Sec Resource (re-) negotiation capability Other Routing optimization Yes Service portability Not applicable |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.9.3 Network Access Identifier | The Network Access Identifier (NAI) is the user ID submitted by the client during PPP authentication (or authentication on any other link frame protocol which has authentication packets which carry login prompt information such as username and password). A roaming user dials into a local network access server (NAS) using PPP, authenticates via link control protocol, identifying itself using the Network Access Identifier. The purpose of the NAI is to identify the user as well as to assist in the routing of authentication request by providing the user's home authentication server through the NAI. When using Mobile IPv4 over PPP, the NAI is used as the user (or mobile node) identification instead of the IP address of the mobile node. As described in the Mobile IPv4 section, the mobile node may request its preference of the type of care-of address. The request could be handled via options provided in IPCP configure request if PPP is used between the mobile node and NAS. In this context, the request is negotiated with the NAS. If the NAS, possibly acting as foreign agent, grants the mobile node access to the Internet, it would send agent advertisement messages on the PPP link towards the mobile node. The Network Access Identifier is of the form username@realm, where the username portion can contain any printable ASCII characters, and the optional realm portion corresponds to a domain name (conforming to the best current practice). The realm portion is used to locate user's home network. Table 5: Analysis of NAI Criteria RoamOPS NAI User NAI Terminal None Application None Identities recognized Location identity Assigned IP address Stability of protocols Internet-draft Critical protocol elements NAS, AAA server Handover capability Not applicable Mobility elements involved in handover phase Not applicable Mechanism to reach the terminal None Reachability status flags None defined QoS RSVP Codec Not applicable Security CHAP, IP Sec Resource (re-) negotiation capability Other Routing optimization Not applicable Service portability Partial (service parameters are transferred from home AAA server to NAS) ETSI ETSI TR 101 338 V1.1.6 (2000-07) 34 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.9.4 Session Initiation Protocol | Recently, within IETF, new protocols have been drafted that provide personal mobility. One such protocol is known as Session Initiation Protocol (SIP). SIP is an application protocol that can establish and control multimedia sessions or calls. The protocol draft indicates that personal mobility provided by SIP is based on the use of a unique personal identity. SIP could offer users some freedom of access from different locations using different hosts. SIP has the capability of locating registered users by providing a location service through a SIP redirect or proxy server to obtain information about a callee's possible location(s). Users register to a registrar server by sending REGISTER requests. A registrar is typically co-located with a proxy or redirect server and may offer location services. The REGISTER request allows a client to let a proxy or redirect server know at which address(es) it can be reached. In order to set-up a session to a registered user using SIP, an INVITE method is sent from the calling host to a SIP server which could either be a proxy or redirect server. The SIP server may request the location of the called user from the location server. Once the location of the called user is returned, meaning called user@host, where the host indicates the domain and host name where the user had last been located, the SIP server, if proxy, initiates another INVITE to that new address. The SIP proxy server waits for the result, and when successful, it would expect to receive a 200OK that will then be sent to the calling user. The calling host would send an acknowledgement to the 200OK back to the SIP server, which will forward it to the called user's host to indicate that the end-to-end session has successfully been initiated. If the SIP server includes the registrar functionality, it may not need to query the location server for the location of the called user if the called user had previously registered within the same SIP server. There are other different mechanisms that are available within SIP to locate a user. A mechanism such as multi-hop "searches" for a user is supported where, when a call request is made to a particular address, a SIP server is contacted at that address. As this SIP server may not be the machine where the callee is currently residing at, the server can proxy the request to one or more additional servers. These servers may in turn proxy the request to multiple servers in parallel. Just like (current) ITU-T Recommendation H.323 [28], SIP does not address terminal mobility. It does not address wireless aspects either. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.10 H.323 Mobility | Like cellular phone services, mobile Internet telephony demands seamlessly roaming while conversation is in progress. Under the current Version of H.323 service scope, however, host mobility is forbidden, resulting from the underlying IP mechanism that implicitly assumes that a host is fixed. Moreover, Voice over IP service is a real-time connection-oriented service over packet-switched IP-based networks. Through proper call setup signalling with the H.323 Gatekeeper, the address of the target endpoint (i.e. callee or called party) can be resolved before call establishment, enabling the service redirection to be completely handled in the application layer. Thus, it realizes mobile IP telephony services with IP. This approach enables mobility support without the need for additional new entities and with minimal modifications to the H.323 standard, allowing such mobile IP telephony service to be a valued-added feature in the existing H.323-compliant Internet telephony systems. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 35 5.11 Public Access Mobile Radio (PAMR) and Private Mobile Radio (PMR) ITU has included in its Report IETF RFC 2003 [16] on 'spectrum efficient digital mobile systems for dispatch traffic', using digital modulation and trunking technologies: TETRA ETS 300 392 [12] and ETS 300 393 [13] and ETS 300 396 [14], APCO25, IDRA, DIMRS, TETRAPOL, IETF RFC 2002 [15], EDACS, FHMA. These Voice and Data digital systems are dedicated to Private Mobile Radio (PMR) where the user owns the network and Public Access Mobile Radio (PAMR) where an operator shares the network between several users, typically Large business, Utilities, Transportation, Public Safety and Emergency forces. Network size is scalable from one cell, through country, continent, to global, and from a few tens of subscribers to many millions of subscribers. Typically PMR/PAMR operates as narrow band (low bandwidth) using RF carrier spacing of 25 kHz and 12,5 kHz with 1 to 6 traffic channels per RF carrier. Carrier (resource) management is achieved through the use of trunking methods. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.11.1 Specificities of PAMR and PMR wireless digital networks | The specificities of wireless digital networks that have evolved for Private Mobile Radio (PMR) and for Public Access Mobile Radio (PAMR) include: - rapid call establishment (tens of milliseconds); - group call (point-to-multipoint); - broadcast call; - open channel (all informed nets); - out of network point-to-point and point-to-multipoint (direct-mode); - range extension by gateways and repeaters; - data and speech optimized; - secure; and - scaleable. PMR/PAMR systems where specified at the radio interface offer a number of access technologies representative examples of which are the TDMA based TETRA ETS 300 392 [12] and ETS 300 393 [13], and the FDMA based TETRAPOL, IETF RFC 2002 [15] systems. The different radio access technologies allow common infrastructures to optimize local area coverage where in general TDMA systems favour high user densities and small cells with FDMA systems finding favour in lager cells with lower user densities. The basic services of Individual and Group calls, Broadcast calls, Emergency calls, Open channel are, in common with ISDN, extensible by supplementary services that include: call forwarding (conditional and unconditional); secondary call authorization; ambience and discreet listening; dynamic address assignment. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.11.1.1 Mobility services in PMR/PAMR | Generic mobility in PMR/PAMR is resident in layer 3 of the protocols and is linked to the primary subscription identity. Alternative subscriber identities are bound to this mobile identity and will include group identities, alias identities, and mapping of equipment identities to mobile identities. Handover (i.e. transfer of call handling from cell to cell) is provided by co-operation of the call handling protocol handlers (at layer 3) with the MM protocol handlers. In most cases handover is not restricted when moving between cells of different networks. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 36 |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.11.1.2.1 TETRA | TETRA offers session oriented mobility. A TETRA session begins with registration of location that registers the network address of the terminal to the network and allows all subscribed services for that network address to be delivered to the terminal. As a terminal moves the lower layers of the protocol continually monitor the link performance and update the registration as the mobile terminal moves between serving base stations and cells. When the serving cell changes between networks mobility information is exchanged such that calls in progress can be restored. Essentially TETRA applications are unaware of the actions of the mobility management protocol (as for any OSI application). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.11.1.2.2 GSM Phase 2+ Advanced Speech Call Items (ASCI) | GSM ASCI offers a subset of PAMR services (Group call, priority, Specific supplementary services). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 5.11.1.2.3 Inter technology SIM roaming | An alternative to mobility by MM protocols is mobility of service between technology domains by SIM roaming. This is being explored in SMG9 and in EPT.7 and by TETRAPOL. |
681a67b945c1c5f10d955076243cde3f | 101 338 | 6 Analysis of roaming technologies | These tables identifies the common elements used in the roaming technologies discussed in the present document to provide mobility. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 37 Table 6: Mobility mechanism part-1 Mobility mechanism evaluation table (part I) Identities recognized Mobility mechanism U S E R T E R M I N A L A P P L I C A T I O N Location identity (note 3) Stability of protocols Critical protocol elements (note 1) (and potential for recuperation) Handover capability (note 2) Mobility elements involved in handover phase GSM (5.1) IMSI IMEI MS ISDN LAI, CellID Stable MS, BSC, MSC, VLR, HLR Yes MS, MSC, VLR UMTS/3GPP r99 (5.3) IMUI IMEI MS ISDN , PDP RAI, LAI, CellId progressing MS, 3G-MSC/VLR, RNC, HLR, 3G- SGSN, 3G-GGSN Yes MS, RNC, 3G-MSC/VLR, 3G-SGSN GPRS (5.7) IMSI IMEI PDP RAI, CellID Stable MS, SGSN, GGSN, VLR, HLR Yes (note 4) MS, SGSN, VLR ANSI-41 (5.2) MIN MSN MIN CellID Stable MS, BSC, MSC, VLR, HLR Yes MS, MSC, VLR SIP (5.9.4) u@d Mobile IPv4 (5.9.1) IP Addr, NAI (note 5) IP Addr Port COA Prop. std Mobile node, home agent, foreign agent Limited MN, HA, FA Mobile IPv6 (5.9.2) IPv6 Addr, NAI (note 6) IPv6 Addr Port, flow label COA I-D Mobile node, home agent, correspondent node Yes MN, HA, CH RoamOps/NAI (5.9.3) NAI None None None I-D NAS, AAA servers No N/A PAMR /TETRA (5.11) (I)TSI TEI LAI Cell Id Stable MS, BS, SwMI, VDB, HDB Yes MS, BS, HDB,VDB NOTE 1: E.g. protocol time out restrictions/limitations or delay sensitivities. NOTE 2: Handover capability as in handover of mobile set between base stations. NOTE 3: E.g. GSM area identifier. NOTE 4: I.e. cell re-selection and RA update. NOTE 5: NAI is required when RFC 2290 PPP/IPCP Mobility Extensions are used. NOTE 6: NAI is required when RFC 2290 PPP/IPCP Mobility Extensions are used. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 38 Table 7: Mobility mechanism part-2 Mobility mechanism evaluation table (part II) Mobility mechanism Mechanism to reach the terminal Reachability Status flags (note 1) Resource (re-)negotiation capability Routing optimization Service Portability (note 2) Special considerations/ Notes Q o S C O D E C S E C U R I T Y O T H E R GSM (5.1) Yes Yes Yes Optional Using CAMEL UMTS/3GPP r99 (5.3) MSRN, GTPiD Unattached, attached, active PDP cntxt Yes Yes Yes Optional VHE/OSA GPRS (5.7) Unattached, attached, active PDP cntxt PDP Act. N/A RA Upd. Yes (if using context of VPLMN) Yes ANSI-41 (5.2) SIP (5.9.4) Mobile IPv4 (5.9.1) ICMP messages RSV P N/A IP Sec Optional (note 3) N/A Mobile IPv6 (5.9.2) ICMPv6 messages N/A IP Sec Yes N/A RoamOps/N AI (5.9.3) N/A RSV P N/A IP Sec N/A Partial PAMR /TETRA (5.11) Yes No Yes Infrastructure dependent NOTE 1: E.g. terminal known, terminal located, terminal off. NOTE 2: I.e. capability for user profile exchange in the protocol. NOTE 3: Requires support from correspondent node (see Internet Draft mobileip-optim). The analysed roaming protocols can be divided into three main categories: 1) Protocols providing only transport-level connectivity (e.g. Mobile IP, GPRS); 2) Protocols providing both transport- and application-level connectivity (e.g. GSM); 3) Protocols providing only application-level connectivity (e.g. SIP). Division of the roaming and mobility management operations into application-specific and transport-specific operations: • Paging, i.e. peer-initiated attachment at transport level; • Attachment at transport level and at application level; • Registration/location update at transport level and at application level; • Roaming number/address query at application level; • Routing optimization at transport level and at application level. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 39 Roaming requires a home function, which stores the up-to-date information required to reach the roaming subscriber. Most of the above roaming technologies have also a separate visited function. The cases without a visited function assume transport-level connectivity provided by means outside their scope. Although the separate visited function may have only a few duties at the application level, having an application-level visited function has clear benefits, especially when implementing location-aware services and when distributing the implementation of the various services between home and visited operator networks. Identifying the roaming entities is done in various ways. However, it is clear that the terminal needs to be identified at transport layer. The subscriber, or rather the subscription identity may be separate from the terminal identity at the transport level. At the application level, the telephone application itself needs to be identified in order to route calls to it. An application-level user roaming identification is also needed. This user roaming identification may be separate from the actual user name used by other users. The list of possible identifications include at least the following items: • Terminal identifier (transport address, hardware identifier); • Subscription identifier at transport level; • Application identifiers (the access points/transport addresses of the application at transport level); • User roaming identifier (subscription identifier at application level, which may or may not be different from subscription identifier at transport level); • User identifier (user name at application level). |
681a67b945c1c5f10d955076243cde3f | 101 338 | 7 Recommended roaming technology | The following recommendations and guideline for the TIPHON roaming/mobility specification have been collected. The scope of the TIPHON roaming/mobility specification is roaming at the TIPHON application plane. If wireless or wireline access network supports roaming/mobility at IP or lower layers, e.g. Mobile IP or GPRS the TIPHON roaming/mobility may or may not take advantage of the transport plane roaming/mobility. However, the modifications to the transport plane or any access networks, if desired, are out of the scope of the TIPHON roaming/mobility. The TIPHON roaming/mobility solution should based on the model where application mobility management is handled by the core network elements, i.e. between Service Control and User Control functional elements. The model implies a User Control element on the service layer with registration/mobility management information flows are included into the TIPHON architecture at application plane (see figure below). The model should also require as few modifications as possible to the User-to-Network Interface, i.e. H.323 or other existing call control protocols. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 40 SC CC SC CC DU D CU C DC BC BC CB MP M M MP FFS B SC CC BC MP SC CC DC BC CB BM MP DN CN B M Services Call Control Media Bearer Control IP Network SCN BM UC RN RN R R Figure 6: The (note) User Control functional element and the registration/roaming information flows adapted to the TIPHON scenarios 1 and 2 NOTE: Similar figures for other scenarios are to be included in TS 101 337 [30]. Information flows to and from the User Control Element shall be mapped to separate reference points from other service-specific signalling. Required procedures for mobility management protocol shall be specified as a part of the TIPHON roaming/mobility recommendation. These procedures shall cover common aspects of roaming technologies listed in the analysis section (clause 6) of the present document. For smooth interoperability with other mobility networks it is recommended that the TIPHON mobility management protocol follows basic principles of the MAP protocol. However, in order to enable widespread utilization within the Internet the mobility management protocol should not depend on any SS7 protocol layers nor SS7 addressing. The TIPHON roaming/mobility specification shall allow user roaming between TIPHON and existing mobile networks, e.g. GSM SIM roaming and ANSI-41, and between TIPHON and 3G networks. More detailed requirements, roaming scenarios, etc., will be specified in TS 101 337 [30]. The Recommended roaming technology: - should support wireline or wireless IP terminals e.g. an H.323 terminal; - should be based on the TIPHON system in an totally IP-based network; - should support roaming of legacy mobile terminals; and - should re-use all or most of the TIPHON protocols and IP infrastructure. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 41 The Recommended roaming technology should support the following scenarios: A. Changing Network Point of Attachment: 1) Intra-zone, Inter-zone, and Inter-domain roaming; 2) Handover (MT only) resulting in a changing IP address. B. Changing IP Application Point of Attachment: 3) Intra-zone, Inter-zone, and Inter-domain roaming; 4) Handover (MT only) resulting in a changing IP address. C. Interworking: 5) Network interworking: connections between TIPHON and legacy mobile networks (e.g. GSM, ANSI 41, UMTS,...) and connections between TIPHON and PSTN or other networks; 6) Tandeming minimization; 7) Minimizing transcoding events within media streams; 8) Terminal interworking: use of legacy mobile terminals (e.g. GSM handset, H.324 terminal, H.320 terminal, etc.) to communicate with TIPHON, including mapping of user identifications between TIPHON and legacy mobile networks. ETSI ETSI TR 101 338 V1.1.6 (2000-07) 42 Bibliography The following material, though not specifically referenced in the body of the present document (or not publicly available), gives supporting information. - C Perkins, D. Johnson, Work in progress - INTERNET-DRAFT draft-ietf-mobileip-optim-08.txt: "Route Optimization in Mobile IP", March 1999. - Charles E. Perkins, Mobile networking through Mobile IP, tutorial, 1997. - David B. Johnson, Charles Perkins, Mobility support in IPv6, draft-ietf-mobileip-ipv6-07.txt, Nov. 1998. - G. A. Thom, "H.323: the Multimedia Comm. Standard for Local Area Networks," IEEE Comm. Magazine, pp. 52-56, December 1996. - Henning Schulzrinne, Jonathan Rosenberg, A comparison of SIP and ITU-T Recommendation H.323 for Internet telephony. - Mobility management, Part 500, CDPD system specification. - ETSI EN 301 344: "Digital cellular telecommunications system (Phase 2+); General Packet Radio Service (GPRS); Service description; Stage 2 (GSM 03.60 Version 7.1.1 Release 1998)". - ETSI TR 101 307 V2.2.2: "Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON); Requirements for service interoperability; Phase 2". - ETSI TS 100 522 V6.1.0: "Digital cellular telecommunications system (Phase 2+); Network architecture; (GSM 03.02 Version 6.1.0 - Release 1997)". - ETSI TS 101 313 V0.4.2: "Telecommunications and Internet Protocol Harmonization Over Network (TIPHON); Network architecture and reference configurations; Phase II: Scenario 1 + Scenario 2". - ETSI TS 101 350 V6.1.0: "Digital cellular telecommunications system (Phase 2+); General Packet Radio Service (GPRS); Overall description of the GPRS radio interface; Stage 2 (GSM 03.64 Version 6.1.0 Release 1997)". - GSM Association Permanent Reference Document: TG.34, Target 3G network requirements, Version 3.0.0. - GSM MoU Permanent Reference Document: TG.25, UMTS Roaming/Mobility Aspects, Version 3.0.0. - GSM MoU Permanent Reference Document: TG.30, Requirements for the third generation system architecture, Version 3.1.0. - GSM MoU Permanent Reference Document: TG.37, UMTS access network requirements, Version 3.0.0. - IETF RFC 1889 (1995): "RTP: A Transport Protocol for Real-Time applications", H. Schulzrinne et al. - IETF RFC 2138 (1997): "Remote Authentication Dial In User Service (RADIUS) - C. Rigney, A. Rubens, W. Simpson, S. Willens, Merit, Daydreamer, Livingston". - IETF RFC 2194 (1997): "Review of Roaming Implementations - B. Aboba, J. Lu, J. Alsop, J. Ding, W. Wang. Microsoft, AimQuest Corp., i-Pass Alliance, Asiainfo, Merit Network, Inc.". - IETF RFC 2477 (1999): "Criteria for Evaluating Roaming Protocols - B. Aboba, G. Zorn, Microsoft Corporation". - ITU-T Recommendation H.225.0 (1996): "Media stream packetization and synchronization on non-guaranteed quality of service LANs". - ITU-T Recommendation H.235 (1998): "Security and encryption for H Series (ITU-T Recommendation H.323 and other ITU-T Recommendation H.245-based) multimedia terminals". - ITU-T Recommendation H.245 (1998): "Control protocol for multimedia communication". ETSI ETSI TR 101 338 V1.1.6 (2000-07) 43 - MI/CTM-000001: "Cordless terminal Mobility (CTM); Global System for Mobile communications (GSM); Intelligent Network (IN); CTM/GSM internetwork roaming using IN; Feasibility study". - TIA/EIA-136-330 DRAFT TEXT V2.0, Packet Data Overview. - TIA/EIA-136-932 DRAFT TEXT V1.2, Stage 2 descriptions for Packet Data. - UMTS 22.00 V2.0.0, UMTS Phase 1. - UMTS 22.01 V3.5.0, Service aspects, Service principles. - UMTS 22.71 V3.1.0, Service aspects, Automatic establishment of roaming relationships. - UMTS 22.71: "Universal Mobile Telecommunications System (UMTS); Automatic Establishment of Roaming - Relationships". - UMTS 23.01 V1.0.0: "General UMTS architecture". - UMTS SMG work programme for UMTS, UMTS 30.00 V3.6.1. - 3G TS 22.121: "Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS);Service aspects; The Virtual Home Environment". ETSI ETSI TR 101 338 V1.1.6 (2000-07) 44 History Document history V1.1.6 July 2000 Publication |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 1 Scope | The present document introduces the activities of the Verification-Demonstration-Interoperability (VDI) working group of TIPHON which organizes interoperability events and provides remote testing facilities (Implementers Net). |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 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] TS 101 335: "Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON); Test specifications". [2] ITU-T Recommendation H.323: "Packet based multimedia communications systems". [3] ITU-T Recommendation H.245: "Control protocol for multimedia communication". [4] ITU-T Recommendation H.225.0: "Call signalling protocols and media stream packetization for packet-based multimedia communication systems". |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 3 Abbreviations | For the purposes of the present document the following abbreviations apply: BRI Basic Rate Interface CoIP Conferencing over IP Activity Group of IMTC IMTC International Multimedia Teleconferencing Consortium INOW! Interoperability NOW, Activity Group of IMTC ISDN Integrated Services Digital Network LAN Local Area Network NDA Non-Disclosure Agreement PBX Private Branch eXchange PRI Primary Rate Interface PSTN Public Switched Telephone Network STF Specialist Task Force VDI Verification-Demonstration-Interoperability VIMP Virtual Interop Meeting Place WG Working Group ETSI ETSI TR 101 334 V3.1.1 (2000-01) 7 |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4 Interoperability Testing | |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.1 Purpose/ Objectives | The purpose of interoperability testing is to verify the TIPHON specifications and interoperability of different implementations. These tests can either take place in a single room, “classic" or “face-to-face" Interoperability Events, or can be spread over the whole world using remote connectivity, then they are called remote Interop events. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.2 Testing | Testing will verify all TIPHON scenarios (that is, PC to PC, PC to Phone, Phone to PC, and Phone to Phone). Testing will attempt to completely demonstrate and debug these services, rather than just concentrate on the specific protocol elements that are required. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.3 Privacy | The result of the tests will not be in any case available outside TIPHON membership, nor may it be used in any case under any situation to promote some products as being "more" TIPHON compliant than others, or for any other purpose other than the verification and debugging of the TIPHON specifications. There will be no formal kind of NDA to be filled out, but there is always a kind of gentleman’s agreement not to disclose any individual results. Documents that request changes to the TIPHON specifications as a result of the Interoperability events will not directly reference the vendor that found the fault. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.4 Responsible WG | Interoperability events will be operated under the responsibility of WG6, with support from the relevant protocol generating and specifying WGs (i.e. WG3, WG4, and WG5). |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.5 Test Procedures | Test specifications of all TIPHON scenarios can be found in TS 101 335 [1]. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.6 Test Scoring | In tests which are scored, score sheets are distributed based on TS 101 335 [1]. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.7 Participation | |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.7.1 Joint events | TIPHON interoperability events are in general organized jointly with IMTC CoIP. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 4.7.2 Who can participate | Participation is open to ETSI members, ETSI associate members, IMTC members, and companies in the application process to become a member of ETSI or IMTC. Participants need to have products or services available for testing with other companies. Companies simply wanting to observe the testing will not be allowed to attend the event. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 8 |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5 Interoperability Events | Interoperability events can take place as face-to-face events, or as remote events. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.1 Face-to-face Interoperability Events | The classical way to test interoperability is to meet in a room and connect multiple systems together. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.1.1 Organization | Interoperability events are in general organized together with the CoIP (Conferencing over IP) Activity Group of IMTC (International Multimedia Teleconferencing Consortium). Annex 1, "Guidelines for the organization of interoperability events", summarizes the experience gained from multiple interoperability events and may prove useful for future organizers of Interoperability events. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.1.2 Registration | Prior to any Interop the participants have to register. To optimize this process and to easily provide detailed information to the other participants ETSI has installed the VIMP. More details are described in clause 7 of the present document. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.1.3 Scheduling | Scheduling is one of the most difficult aspects of Interop Events. As a consensus we can state that the participants prefer 65% of the time as ad hoc, self scheduled tests and 35% of the time as scheduled by the organizers. Scheduled tests in face-to-face interoperability events are intended to test the interoperability of a large number of participants in a minimum of time. Thus the timeslots are pretty short and there is no time for the companies to debug. Extensive analyses and debugging can take place in the ad-hoc test time after the scheduled tests. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.1.4 Frequency | Here is some feedback collected at two post Interoperability Events in Boston and Sophia Antipolis. How many Interop Event should there be per year? 4-99 Boston 6-99 Sophia Antipolis 1 per year 0% 2 % 2 per year 18 % 18 % 3 per year 30 % 45 % 4 per year 49 % 30 % 6 per year 3 % 5 % Average 3,4 3,2 ETSI ETSI TR 101 334 V3.1.1 (2000-01) 9 |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.2 Remote Interoperability Events | Remote Interoperability Events provide companies the opportunity to test interoperability in their own labs without buying other companies equipment. They can interconnect to other parties via the public Internet or the ETSI ISDN router. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.2.1 Organization | The organization of a remote interoperability event is different from a face to face event. There is no need to arrange a room and prepare accommodation, but in order to organize an effective event the information for the participants have to be much more detailed and precise, as communication is much more complicated and solving simple problems may be very time-consuming. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.2.2 Registration | Prior to any Interop the participants have to register. To optimize this process and to provide detailed information to the other participants in any effective way, ETSI has installed the VIMP. More details are described in clause 7 of the present document. The information provided about other participants equipment is very important for remote interoperability events, as it is much more complicated to collect details at a later stage. These details include: - Time of day the contact person is present in the company and able to do testing; - Ability to test using the pubic internet; - Ability to test using the TIPHON Interop Router; - IP-Address of device ( if known and important for test); - Alias the Endpoint is going to register with; - Gateway Prefix, the Gateway is going to register with, or Endpoint Alias; - Number an Endpoint has to dial to reach a telephone connected to the Gateway. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.2.3 Communication | The communication is simple if you are sitting together in one room. If you test remotely, you must have a telephone conference or a simple chat tool to communicate the progress of the test. A chat tool also allowS the co-ordinator to be informed about the progress of a test. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.2.4 Time | As TIPHON is a world-wide project we have different time zones for the participating companies. It is not complicated to calculate the actual time in another parts of the world but causes sometimes confusion. To simplify this, TIPHON should use a common time-base to schedule tests. UTC or the InternetTime can be used as a common time. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 10 |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 5.2.5 Scheduling | Scheduling is one of the most difficult aspects of Interop Events. As a consensus we can state that the participants prefer 65% of the time as ad hoc, self scheduled tests and 35% of the time as scheduled by the organizers. Scheduling of a remote interoperability event has to take some specialities into account: A test can either use the public internet or the Interop router but this can not be mixed due to routing reasons. - Companies have to be available at the same time; - The time for each configuration has to be at least 1-2 hours long, to give participants time for debugging; - Schedules including all relevant data have to be delivered to the participants; - The participants have to check, if they can operate with the parameters of the others like Endpoint Alias or Gateway Prefix if not they have to announce this. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6 Implementers Net | |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6.1 Purpose/Objectives | A new framework called Implementers Net is being created under the umbrella of WG6 to support Interoperability testing for TIPHON equipment manufacturers only. This framework is not be used for demonstration or trial, and access will be tightly controlled. The Implementers Net is currently being set up and replaces the TIPHON-Net. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6.2 Architecture | The architecture contains a central ISDN/PSTN router, where vendors can dial up with either an ITU-T Recommendation H.323 [2] terminal, equipped with an ISDN card, or an ISDN router. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 11 Company A with full H.323 zone Central ISDN ROUTER Company B H.323 Terminal with ISDN Card or modem H.323Terminal ISDN Router Ethernet H.323 Gatekeeper H.323 Gateway H.323 MCU ISDN ISDN/PSTN Company C with full H.323 zone H.323Terminal ISDN Router Ethernet H.323 Gatekeeper H.323 Gateway H.323 MCU ISDN Company D H.323 Gateway with ISDN Card or modem ISDN/PSTN PSTN Telefon PSTN Telefon Internet Figure 1: Implementer's Net Architecture |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6.3 Procedures | The Implementers Net is used for ad-hoc testing (i.e., it is up to the individual companies to find partners) and for "Remote Interoperability Events." The "Virtual Interoperability Meeting Place" (see next chapter) will be used to schedule tests and find like-minded partners. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6.4 Requirements | Each participant needs either an ITU-T Recommendation H.323 [2] terminal, equipped with an ISDN card, or an ISDN router connected via LAN to the local ITU-T Recommendation H.323 [2] testbed or alternatively the public internet can be used. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 12 |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6.5 Technical details of the Dial up ISDN router | The ISDN router supports 30 concurrent ISDN or analogous connections. The router is configured with incoming lines only (30). Phone costs for dialing in are paid by the callers. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 6.6 Administration of the ISDN router | The ISDN router is administered by the STF 114 or ETSI network administration. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 7 The Virtual Interoperability Meeting Place (VIMP) | |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 7.1 Purpose | The VIMP is the central organizational element for Interoperability events and the use of the Implementers Net. The VIMP contains a database of the companies and TIPHON compliant products. Before participating in any interoperability event or using the Implementers Net, each company has to register a primary contact and its equipment with the VIMP. This registration can either be specific for the upcoming event or continuous. The collected data enables all implementers to look for partners for ad-hoc tests during or after the interoperability events. The collected information is the basis for the organizer of the Interoperability event to schedule the tests and for the other participants of the event to find adequate partners for ad-hoc testing. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 7.2 Structure | The virtual meeting place contains form fields where engineers enter all the necessary information such as: • equipment (endpoint, gateway, gatekeeper, MCU); • codecs supported; • which version of H.xxx (ITU-T Recommendation H.323 [2], ITU-T Recommendation H.245 [3], ITU-T Recommendation H.225.0 [4], …) they implement; • which features within a version are supported (Fast connect, ITU-T Recommendation H.245 [3] tunnelling, Gatekeeper routed signalling, Direct routed signalling, …); • what they would like to test; • when they would like to test; • Names & addresses of engineers; • test scenarios with scoring guide; • availability for companies to enter anonymously results of their tests. The homepage is publicly available and has a branch to a member section. The member section is password-protected and only accessible to test engineers, ETSI-TIPHON STF 114 and the IMTC CoIP chair. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 7.3 Organization | The VIMP is administered by the STF 114 and ETSI network administration. The STF 114 and IMTC CoIP will play a pro-active role in managing and organizing remote tests (ad-hoc remote tests; remote interoperability events). ETSI ETSI TR 101 334 V3.1.1 (2000-01) 13 |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 8 Implementers mailing list | |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 8.1 Purpose of TIPHON_Implementers | The purpose of this Mailing List is to announce interoperability tests and discuss technical details in a private and secure way. Access is controlled by the ETSI STF 114, WG6 chairman and IMTC CoIP chairmen, and only equipment manufacturers will be allowed to join. The Mailing List will be organized and administered by the STF 114. |
a1765d8d398ae82d88c0967bdc40ed38 | 101 334 | 8.2 How to join the TIPHON_Implementers List | 1) You send a subscribe request in the body part (not the subject) of a message to the mailing list manager LISTSERV@LIST.ETSI.FR. - SUBSCRIBE TIPHON_Implementers (firstname surname); - Two separate words are required for firstname and surname. 2) The mailing list manager may check that it can reach your e-mail address by sending you a message which you will have to confirm. If sent, the message will contain a line with the word "OK" followed by a code, e.g. OK sbc4na. Put that line in the body (not the subject) of a message and send it to LISTSERV@LIST.ETSI.FR. 3) The subscription request will be sent to the list owner (STF 114) who will decide, in agreement with the WG6 chairman and IMTC CoIP chairmen, if the request will be approved or not. 4) The list will confirm that you have been successfully added by sending you a file with information on the list and some helpful hints. Keep this carefully. You may need it to change your settings or to leave the list. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 14 Annex A (informative): Guidelines for the Organization of Interoperability Events The following is a collection of experiences and guidelines, resulting from two interoperability events, which may prove useful for the organization of future interoperability events. A.1 Responsibilities - There needs to be one person with the overall responsibility of the event. - Some tasks will be delegated. It has to be clear who is responsible for what, e.g. setting up the network, making arrangements with the hotel, etc. A.2 Timing - Make sure that the location where the interoperability event takes place is booked early enough. Hotels may not be able to have e.g. a ballroom available for an entire week unless reserved early enough. - Inform participants early enough when the interoperability event is to take place (2-3 months). A.3 How to register Registration should make extensive use of the VIMP. A.4 Guest rooms in hotel Send list of hotels with the event kit, or, if event takes place in a hotel, make arrangements with hotel to reserve rooms for the event. A.5 Deadline for registration Make it about 3 weeks in advance. Be prepared that there will always be registrations coming in after the deadline. A.6 Rental of Equipment Companies should and do rent monitors. At the Sophia and Boston interoperability event, about 20-30 monitors had been rented. Arrange special deal with a local rental company. It is the responsibility of the companies to contact the rental place. A.7 Shipping of equipment About 20% of companies will ship big crates (up to 2m x 2m) with their equipment; others have all they need on their laptop. Equipment needs to be shipped off early enough (2/3 weeks), but shipping companies are pretty good in making sure that the equipment arrives on time. Shipping is the responsibility of the companies. Customs shouldn’t be a problem either, but expect a couple of phone calls from an airport on what to do with a particular shipment. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 15 A.8 Facilities - Location: often in hotels. Entire network has to be built up from scratch. Rooms may not be available until the event actually starts, or there may be additional costs for renting it. The test facility should be very close to hotels and restaurants. - Test room: Each participant should have at least a desk space of 1 m x 1 m by default. The test room has to be secured and available 24 hours per day. The cabling should be arranged in a secured way to avoid damage of equipment. - Secured Storage Room: to store anything safely on-site, to avoid transportation to the hotel. To store boxes waiting for rental return or shipping. For instance, a locker could be a nice feature. - Safe shipping and Rental Facilities: especially at the beginning and at the end of the event, for delivering and returning of rental equipment. A receipt from the rental company is required when returning back the equipment. - Space: in Boston, there was a 116 ft x 53 ft = 6 150 square feet (about 35 m x 16 m = 560 m2) ballroom in a hotel. This was a lot and no problem to host about 30 companies with 80+ people. 116’ 53’ Electrical power 1 2 3 8x2 foot tables 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 ISDN Switch on 8x2 foot table PABX on 8x2 foot table Network Router and Hubs on 8x2 foot tables Power & Network Cable Runs Figure 2: Example of room layout - Seating: prearrange seating. It saves time and avoids space fragmentation. Put signs with company names on tables. - Microphone: a must. - Computer connected to PC screen projector: nice to have to project announcements on the wall, or changing schedules, map of the room, status of devices, etc. Should be visible from all places. A second PC screen projector would be nice, especially for displaying the map of the room permanently. - Printer: a must (e.g. in business office of hotel). Should be operated as a self-service. - Copy machine: a must (e.g. in business office of hotel). Should be operated as a self-service. - Security: equipment is valuable, and people will ask how secure the place is. On-site security during the night may be required. However, hotels will have security patrolling the hotel and the surroundings anyway, and they may have e.g. motion alarm inside the building, so additional on-site security may not be necessary. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 16 - On-site catering: engineers will be working long hours, and continue debugging software in the hotel. Coffee/tea/water is very much appreciated. Vending machines as well. Make sure that vending machines get filled up. If no sponsors for food can be found (costly: 3 sandwich lunches with potato salad + cookies + ice tea feeding 85 people can easily cost $5,000.-), it is recommended to have sandwiches brought in and the costs be shared by the participants. Going out to restaurants can be time-consuming. Snacks and refreshments should be available all the time (24 hours). If participants are charged for food, it has to be announced in advance. - Garbage cans: easy to forget. A.9 Network The crucial part of the Interoperability event. "Pure" ITU-T Recommendation H.323 [2] interoperability events require only a LAN which can be set up relatively easily from scratch in a hotel within ½ - 1 day, and the necessary equipment (switches, hubs) is readily available. TIPHON interoperability events require in addition a phone network, e.g. a PBX with T1-PRI, E1-PRI and interfaces for the gateways, and analog lines for the telephones. - Power: there has to be at least one power supply for each table. Some hotels have break-up (hubble) boards and can provide a dedicated circuit to each table. Make sure that hotels have long enough power cables that can reach from the break-up boards to the tables. In general, hotels have audio-visual staff who will take care of that. In a hotel, power has to be paid. Extensions should be provided by the participants. - Power Transformers: a few spare power transformers should be available. - LAN: all ports should be switched 10/100 Mbps Ethernet. Switching allows to filter the unicast Ethernet traffic between ports, and avoids LAN segments to be flooded by the traffic of each device; however, multicast and broadcast traffic is not filtered. VLANs (Virtual LANs) facilities allow in addition to test multicast messages, such as Gatekeeper auto-discovery, by keeping all the multicast traffic local to a given virtual LAN. Mini-hubs may be used on booth for using protocol analysers in parallel to device under test on the same switched port. One subnet is sufficient. - LAN-Cabling: if there is no pre-wired network already in place, lots of cabling will be needed. Depending on where they are seated, people need to run to 20-30 m cables to switches or hubs. So be sure to have a role of 1000 ft cat 5 cable available. - Internet connectivity: should be provided so that people can download latest software fixes and check their email, or to allow remote testing and remote debugging. It would be ideal for every table to have Internet connectivity. If cost is an issue, the cost for Internet access could be divided among the participants for an extra fee. - Telephony: PBXs, or PSTN switches, with T1-PRI, E1-PRI, BRI, ... and analog interfaces. The switches should support protocols used in main parts of the world (e.g. 5ESS, DSS1, NI1, ...). In general, companies can support most protocols in the world, so the local ones may be fine. However, engineers present may have worked primarily with one interface only and run into configuration problems. The PBXs and/or PSTN switches should be connected to the outside world to provide connectivity for remote testing and support. An internal communication mean between participant should be provided, such as table phones, and wireless communication (e.g. DECT, talkie-walkie, ...). For future tests, support for SS7 and IN will be needed. - Telephones: should either be provided or brought by the participants. - Test Tools: Third-party ITU-T Recommendation H.323 [2] protocol analyser and LAN analyser will be very helpful in case of suspicious error situation. Additionally, ITU-T Recommendation H.323 [2] loader/traffic generator and IP traffic resequencer /delayer/loser could be very helpful for more elaborated tests. Voice quality measurement tools would become necessary in a near future. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 17 A.10 Information Services - General Web Server: it is important to have an easy accessible location of information during the event. The easiest way would be a Web server, not accessible from the outside. The following functionalities should be supported: upload and download of documents, display of time schedule, FAQ list, room map, available facilities, access to docbox, Do Not Disturb service... - Mail Server: each participant should have access to an email server during the event. This can either be achieved by a local email server or by access to the public internet, so people can access their companies e-mail server. Be aware that some e-mail servers are only accessible if you are not running a firewall. Mailing lists should be used to distribute timely important information, questions of general interest. - VIMP (Virtual Interoperability Meeting Place): the VIMP should be used to schedule ad-hoc testing and for providing detailed information about the features of tested devices. - Free/Busy Service: this service should be used to indicate the current status of a device under test: "Free" (green), "Busy" (red). "Free" will indicate that the device is currently available for test. "Busy" will indicate that the device is currently involved in a test case or is not available. These flags could be sorted by device type and/or company, allowing a quick search for a specific device. - FAQ List: a FAQ list should be maintained and easily accessible. A.11 On-site Staff - Network and System Manager: maintaining the network. - PBX Manager: maintaining the telephone network. - Web/Email/VIMP Manager: maintaining the information services. - Special Testing Tools Manager: operating special test equipment. These people need not to be present all the time, but should be sufficiently available and reachable during the test event (e.g. if the network or the PBX is down during the evening). A.12 Conference Calls It may be useful to have conference calls 2-3 weeks prior to the event in order to sort out final details with the participants. A.13 Sponsors Inquire about sponsors. Some companies may not sponsor an entire event but a lunch or a breakfast. A.14 Event kit / Information package An example of an event kit, i.e. invitation for the interoperability event, can be found on the ETSI TIPHON web site (http://www.etsi.org/tiphon). ETSI ETSI TR 101 334 V3.1.1 (2000-01) 18 A.15 Documents to have ready at the beginning of interoperability event The following documents will have to be revised on the first day, but a first version should be ready upon arrival of the participants: - Floor plan: prearrange seating and have a floor plan with company booths ready before the event. - Phone numbers and IP-addresses: assigned to all companies should be written up in advance and handed out to the companies. - List of participants. - Name badges: needed to make sure no one unauthorized enters the facilities. It also helps to get people to know each other. Have also first names on name badges. A.16 Running the event Scheduling: can be a nightmare. There are 3 ways to do scheduling: 1) Ad-hoc testing: companies find their own partners on site and test whatever they want to test. Good for debugging. 2) Scheduled tests: companies are assigned time slots, what to test, and with whom to test, and score the result of the test. Goal is not to debug but to get a measure of interoperability. 3) Ad-hoc scheduled test: companies are assigned time slots and with whom to test, but can test whatever they want. Some guidelines: - Almost all participants prefer ad-hoc tests because it gives them time to debug. About 2/3 of the time should be reserved for ad-hoc tests. - Do ad-hoc testing on the first day. People may still be setting up their equipment. - Put scheduled testing towards the end when some confidence has been achieved (last 2 days), or do ad-hoc – scheduled – ad-hoc – scheduled testing. - Make time slots of scheduled tests large enough. 15 minutes seems too small. - An entire day of scheduled testing is very demanding. May do scheduled in the morning, ad-hoc in the afternoon. - Schedule complex tests not at the end of a period because people are tired. - If scheduled testing is done, may want to run part of it like a drill: have someone with a microphone tell everybody to stop with test x and move to test y; x minutes left for test y, etc. If this is not done, people will drift off and do ad-hoc testing. trouble-shooting: network staff is needed full-time until everyone is connected. Once everyone is connected, things are usually relatively quiet, but network staff has to be prepared to jump in any time to fix problems. questionnaire: towards the end of the interoperability event, distribute questionnaire to get feedback on the interoperability event. social event: nice to have. If not sponsored, ask who wants to go to some place for dinner. odds and ends: have office supplies ready, additional power plugs, adapters, duct tape, … ETSI ETSI TR 101 334 V3.1.1 (2000-01) 19 A.17 After the interoperability event - Companies have to send back their equipment. Make sure that people don’t forget to put the correct shipping information on their boxes. It happens frequently that shipping orders are missing, or are not correctly filled out. - If score sheets were collected, evaluate. - If questionnaire has been distributed, evaluate. ETSI ETSI TR 101 334 V3.1.1 (2000-01) 20 Bibliography The following material, though not specifically referenced in the body of the present document (or not publicly available), gives supporting information. - http://docbox.etsi.org/tech-org/tiphon/Document/tiphon/05-9905-Bangkok/13TD094-guidelines- for-organization-of-interops.doc - http://docbox.etsi.org/tech-org/tiphon/Document/tiphon/05-9901-InterOp/invite_r1.doc ETSI ETSI TR 101 334 V3.1.1 (2000-01) 21 History Document history V1.1.1 January 1999 Publication V2.1.4 August 1999 Publication V3.1.1 January 2000 Publication |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 1 Scope | The present document applies to disposable Radiosonde transmitters in Meteorological Aids Systems operating on the 400,15 MHz to 406 MHz band. Essential properties; spectrum mask, power level, and centre frequency drift are specified. Further, the present document discuss Radiosonde to Radiosonde interference giving guidelines for frequency management. |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 2 References | For the purposes of this Technical Report (TR) the following references apply: [1] ITU-R Recommendation SA 1165-1: "Technical characteristics and performance criteria for radiosonde systems in the meteorological aids service". [2] ITU-R Recommendation SA 1262: "Sharing and coordination criteria for meteorological aids in the 400.15-406 MHz and 1 668.4-1 700 MHz bands". [3] ITU-R Recommendation SA 1263: "Interference criteria for meteorological aids operated in the 400.15-406 MHz and 1 668.4-1 700 MHz bands". [4] Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio equipment and telecommunications terminal equipment and the mutual recognition of their conformity (R&TTE Directive). [5] WMO-No.49, World Meteorological Organization: "Volume I - General meteorological standards and recommended practices". [6] Doc 7488/2, International Civil Aviation Organisation: "Manual of the ICAO standard atmosphere: extended to 32 kilometres (105,000 feet)". [7] ETSI EN 300 220 (all parts): "ElectroMagnetic Compatibility and Radio Spectrum Matters (ERM); Short Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW". |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 3 Definitions, symbols and abbreviations | |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: assigned frequency band: frequency band within which the device is authorized to operate dropsonde: disposable sonde released with a parachute from an airborne launch platform to perform measurements fixed station: sounding station in a fixed location floatsonde: disposable sonde performing measurements while floating on the sea surface harmful interference: interference that prevents the system to perform the intended task launch site: location where a Meteorological Aids sonde is deployed for use measurement: single act to provide instant information of e.g. temperature, humidity or pressure mobile station: sounding station intended for use in varying locations depending on the needs observation: number of consecutive measurements composing a useful data set ETSI ETSI TR 101 446 V1.1.1 (2002-04) 6 radiosonde: disposable sonde carried up to the altitudes by a balloon to perform measurements of the atmosphere receiving station: generic name for Meteorological Aids receiving equipment rocketsonde: disposable dropsonde carried to the altitudes by a rocket and released at the apogee sonde: generic name for a Meteorological Aids device to perform measurements sounding station: generic name for a location or platform releasing sondes and receiving signals |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: P Pressure, units in hPa T Temperature, units inºC or inºK U or H relative Humidity of the air, units in % RH |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: EESS Earth Exploring Satellite System FM Frequency Modulation FSK Frequency Shift Key GFSK Gaussian Frequency Shift Keying GPS Global Positioning System GTS Global Telecommunication System for meteorological data ICAO International Civil Aviation Organization IPR Intellectual Property Rights ITU International Telecommunications Union Loran-C Long range navigational system - version C Met Sat Meteorological Satellite MSS Mobile Satellite Service RF Radio Frequency S/I Signal to Interference ratio S/N Signal to Noise ratio SRD Short Range Device VCO Voltage Controlled Oscillator WMO World Meteorological Organisation |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 4 Executive summary | Short Background information: The Meteorological Aids allocation is 400,15 MHz to 406 MHz. The sub band 400,15 MHz to 401 MHz is shared, with MSS (Mobile Satellite Service), and the sub band 401 MHz to 403 MHz, with Met Sat (Meteorological Satellite) and EESS (Earth Exploration Satellite Service). In addition, in Europe, the Ultra Low Power Active Medical Implants have a secondary allocation in the sub band 402 MHz to 405 MHz. Radiosondes, the main Meteorological Aids devices, are released in all European Union and adjacent countries on daily basis. This operation is performed based on agreements within the WMO (World Meteorological Organisation). In addition there are national or regional use of sondes in many countries. Because the Radiosondes are carried aloft with free flying balloons they drift with wind, and may cross borders entering into the legislation area of neighbouring countries. In order to avoid cross border harmful interference an European frequency plan and assignment may be needed to ensure proper performance of observations. The majority of the currently used sondes use free oscillating transmitters and analogue FM modulation. The free oscillating transmitters tend to drift due to the wide ambient temperature variation and decreasing battery voltage. ETSI ETSI TR 101 446 V1.1.1 (2002-04) 7 The present document presents a spectrum mask for transmission encouraging the use of digital modulation, and frequency drift control electronics in disposable sondes. The present document covers Radiosondes. The other Meteorological Aids applications on the same frequency band shall meet the present document when applicable. The other applications are e.g. Dropsondes, Rocketosondes and Floatsondes. The present document meets the requirements of efficient use of the spectrum stated in the R&TTE Directive [4] taking into account the sonde specific issues. System operation, applications and rationale: The Radiosondes are used for weather forecasting and meteorological and environmental research. The international agreements within the WMO suggest at least two, but encourage four, daily observations at each site (fixed land and mobile ship stations). Observation data are distributed to all WMO member countries through the Global Telecommunication System (GTS). The number of sondes used for international weather data exchange within WMO agreement is about a half of the sondes totally used. In other applications the sondes are used more sporadic, but their use can be intensive during measurement campaigns or other special situations. Currently the majority of Radiosonde transmissions are full analogue FM modulation or combined with FSK modulated data. The transmitter is typically a free oscillating one, which tends to drift due to the wide temperature variation and fading power source (battery). This causes usually about ±150 kHz drift (±800 kHz defined by ITU-R Recommendation SA 1165-1 [1]) from the pre-set frequency. For the analogue FM transmitters ITU-R Recommendation SA 1165-1 [1] defines -43 dBc as the limit for spurious (out of band) transmissions. The present document proposes limits corresponding to -60 dBc level and better, and limits the transmission power to 200 mW. The Radiosonde specific issues, compared with other, e.g. typical SRD applications, are: a) The wide ambient operating temperature range: +55ºC … -66,5ºC (10ºC less than ICAO standard atmosphere minimum). b) The high dynamic range of the reception: in the beginning of the observation the Radiosonde is close to the deployment and reception site, and by the end of it, the range may be about 300 km. c) The economy: Radiosonde is disposed after one time use. The present document gives a spectral mask for sonde transmission. Market Briefing: Radiosondes have been in the use for about 60 years. The use of the 400,15 MHz to 406 MHz band has increased during the past two decades, and about half of the sondes in the world use this band. There are some plans to deploy Dropsondes from high altitude platforms close to European coastal area. In addition ship-borne systems have proven to provide useful data for medium range weather forecast. In the Europe, the present annual use of Radiosondes, is about 100 000, and there are about 300 receiving systems. About 100 sites (receiving systems) have WMO catalogue number to report observations to the GTS. The other users fall into different categories covering research, atmospheric science and environmental monitoring. Spectrum requirement and justifications: The development of technology has made a high measurement rate, compared to Radiosondes used in the past decades, possible. In addition to the actual readings, in order to ensure the measurement quality, Radiosondes need to transmit a number of reference, and housekeeping data to the receiving station for analysis. Further, to ensure error free reception, redundancy, e.g. error detection and correction methods, need to be applied. The spectrum mask allows theoretically high-speed, up to 50 kbit/s, transmission using digital modulation. The wide variation in the ambient temperature affects on the transmitter frequency stability even if crystals or synthesizers are used, therefore it is feasible to allow drift of the centre frequency during the operation. The other essential factor in the digital transmission is the property of the local oscillator (VCO). Using an ideal modulation and VCO this spectral mask allows transmission speed of 50 kbit/s. This speed may be sufficient for all foreseen volume Radiosonde applications in future. ETSI ETSI TR 101 446 V1.1.1 (2002-04) 8 The proposed spectrum mask with allowed transmitter drift properties makes 200 kHz channel separation possible. The ITU-R Recommendation SA 1165-1 [1] suggest ±800 kHz drift and 480 kHz spectral mask in worst case for FM-analogy Radiosondes Current regulations: In European Countries only in Germany there are specific requirements, which differ from those given in the ITU specification ITU-R Recommendation SA 1165 [1]. In Germany Radiosonde transmission needs to comply with the generic standard for short range devices (EN 300 220) [7]. |
887dfc404afb2308eac5e9a49a76b6fe | 101 446 | 5 Specifications and recommendations | The essential specifications of the sonde transmitter are given in the following. 1) Effective Radiated Power: maximum 200 mW. 2) Frequency stability: ±20 kHz [ = ±50 ppm] within the ambient temperature range from +55ºC to -66,5ºC, which is 10ºC less than the minimum atmospheric temperature specified by ICAO standard atmosphere. 3) Spectral mask: Frequency offset is given relative to the nominal carrier frequency. Carrier frequency drift is not included. Power is given relative to the power in the nominal carrier frequency in 1 kHz band. Table 1: Spectrum mask Frequency offset from nominal Maximum relative power ±50…100 kHz -34 dBc/1 kHz ±100…200 kHz -40 dBc/1 kHz ±200…300 kHz -48 dBc/1 kHz 4) There are no common European channel assignments for Radiosondes in the Meteorological Aids band from 400,15 MHz to 406 MHz. The presented characteristics support use of 200 kHz separation in frequency between Radiosondes operating in the same geographical area. ETSI ETSI TR 101 446 V1.1.1 (2002-04) 9 Annex A: Detailed application information A.1 Radiosonde application A sounding system comprises of disposable radiosonde ascending with a Hydrogen or Helium balloon, and a receiving station. Radiosonde deployed from aircraft and descending with a parachute are called Dropsondes. In the receiving station the signal transmitted from Radiosonde are converted to quantities and output messages used in meteorology, and then input to Global Telecommunication Network (GTS). Radiosondes with balloon ascend usually up to about 35 km altitude in about two hours, and Dropsondes released from aircraft cover the range from flight level to the ground. Dropsondes are usually deployed over sea areas, where ground based releases are not practical. The balloon borne Radiosondes drift with wind, and at the end of the flight the maximum distance to the release site may be about 300 km in some weather conditions, but typically much less. Radiosondes measures typically atmospheric pressure (P), temperature (T), relative humidity (U or H as American abbreviation reads), and wind speed and direction. Special sondes measure Ozone, other substances, and the presence of radioactive particles. The wind measurement is usually done using Navigational Aid signals from Loran-C or GPS (Global Positioning System). When available the European navigational system Galileo may be applied. The present document does not apply to sondes measuring winds using the Loran-C, and transmitting analogue FM modulated signal. A.2 Transmitters The present document presents specifications for spectral mask of digital modulation. The specification does not impose any methods to stabilize the transmitter or any specific modulation technique. The bit rate 50 kbit/s. is envisioned to be needed for high resolution measurements in the future. The maximum transmission power of 200 mW promotes long range and high bit rate transmission with low bit error rate. A.3 Requirement to wide spectrum The number of Radiosondes, which needs to be tracked simultaneously at a site varies, in addition alien Radiosondes usually are within the telemetry range. The situations given here are only for understanding the operation, and other schemes may exist: a) Fixed or mobile ship stations performing observations according to the WMO recommendations: if the released Radiosonde, using primary frequency, fails but continues to transmit, a new Radiosonde needs to be released using the secondary frequency assigned to the station. b) Sounding stations locating close to each other's need to have different assignments for primary and secondary frequencies. c) Mobile (usually research application) sounding stations performing multiple soundings consecutively. Receiving station tracks at the same time more than one Radiosonde. The earlier released Radiosondes may be far away (e.g. 300 km) from the receiving station while the new one is under preparation in its immediate proximity. In research applications the need to the channel assignment depends on the (research) program objectives ETSI ETSI TR 101 446 V1.1.1 (2002-04) 10 Annex B: Technical information B.1 Technical justifications for spectrum B.1.1 High dynamic range of reception The Radiosonde reception range varies during a sounding from deployment, which is usually near to the receiving system, to the end of the sounding, when the range in some conditions may be up to about 300 km. Table 2: Free space loss of 400 MHz signal Distance free space loss 10 m 44,5 dB 100 m 64,5 dB 1 km 84,5 dB 10 km 104,5 dB 30 km 114,3 dB 100 km 124,5 dB 200 km 130,5 dB 300 km 134,0 dB 350 km 135,4 dB B.1.2 Radiosonde to Radiosonde interference When a second RF signal is set spectrally near to a desired one, it becomes a harmful interfere under certain conditions. If the power of the side lobe of alien signal is high enough degradation of the system performance will occur. The Radiosonde to Radiosonde interference occurs if a Radiosonde receiving station is tracking the target far away, and another Radiosonde released from somewhere else would drift to a close distance. This may happen if near-by release sites use frequencies uncoordinated or the assigned frequencies are too close to each other. Assuming that the interfering Radiosonde would be at 30 km, and the sonde to be received at 300 km distance, respectively the free space losses would be 114,3 dB and 134 dB. The required marginal for successful reception and detection of the GFSK modulated Radiosonde signal, S/N or S/I, is typically about 14 dB with acceptable bit error rate. Consequently at least 33,5 dB is required to separate two adjacent channels. Combining the spectral mask properties, maximum allowed frequency drift given in clause 5, and required receiver band width the channel separation could be 200 kHz. B.1.3 Frequency drift due to the ambient temperature variation Radiosonde passes through the atmosphere, and is exposed to all occurring conditions. The operational temperature ranges from +55ºC to -90ºC may occur, pressure from 1 050 hPa to 3 hPa and humidity from dry, about 10 % RH, to condensing 100 % RH. The wide operation environment range tends to cause temperature related drift to the transmitter. With a synthesized frequency, and crystal controlled transmitters the drift can be reduced substantially compared to free oscillating ones, but not eliminated. The allowed drift specified in the present document is substantially less, but allows, however, more temperature related drift for Radiosonde transmitters than is allowed for SRD devices. ETSI ETSI TR 101 446 V1.1.1 (2002-04) 11 B.2 Current of relevant ETSI standards for ensuring the conformity with technical specifications • ETSI ETS 300 683, (1997): "Radio Equipment and Systems (RES); ElectroMagnetic Compatibility (EMC) standard for Short Range Devices (SRD) operating on frequencies between 9 kHz and 25 GHz ". • ETSI EN 300 220-1 (V1.3.1): "ElectroMagnetic Compatibility and Radio Spectrum Matters (ERM); Short Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW; Part 1: Technical characteristics and test methods". ETSI ETSI TR 101 446 V1.1.1 (2002-04) 12 History Document history V1.1.1 April 2002 Publication |
abd3ec15d3b7f9b4dfa3b9b29f0899ad | 101 445 | 1 Scope | The present document applies to RFID systems operating in the UHF band. RFID belong to the family of non-specific SRDs. It is anticipated that the frequency band proposed in the present document will be dedicated to non-specific SRDs. The present SR Doc is intended to define RFID systems that are used in item management and logistic applications. These applications require reading ranges of at least 2 m that cannot be provided by alternative technologies and at other frequencies. The operation of SRDs in the UHF band is covered by the generic standard EN 300 220-1 [2]. Some of the requirements proposed in this System Reference Document - particularly those relating to power levels - fall outside the generic standard. It will be necessary therefore to raise a new Work Item for the generation of suitable documentation to deal with these issues. The present document contains the technical characteristics for radio equipment referencing CEPT/ERC Decisions and Recommendation CEPT/ERC/REC 70-03 [1]. Table 1 Power class Power level (conducted or radiated) mW 11 100 12 500 xx 2 000 The following information is given in the Annexes • Annex A: Detailed market information; • Annex B: Technical information; • Annex C: Anticipated compatibility issues. |
abd3ec15d3b7f9b4dfa3b9b29f0899ad | 101 445 | 2 References | For the purposes of this Technical Report (TR) the following references apply: [1] CEPT/ERC/REC 70-03 (1998): "Relating to the use of Short Range Devices (SRD)". [2] ETSI EN 300 220-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Short Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW; Part 1: Technical characteristics and test methods". [3] ISO/IEC JTC1/SC31: "Automatic Identification and Data Capture Techniques". ETSI ETSI TR 101 445 V1.1.1 (2002-04) 6 |
abd3ec15d3b7f9b4dfa3b9b29f0899ad | 101 445 | 3 Definitions, symbols and abbreviations |
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