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050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 6.3 Transit network | The TIPHON network as an originating network is shown in Figure 2. Donor Network Recipient Network Originating Network TIPHON Transit Network(s) a b b c Call path a-b - onward routeing Call path a-(release)-c - QoR/dropback Call path c - ACQ Figure 2 ETSI ETSI TR 101 858 V1.1.1 (2000-09) 16 Once again, the requirements... |
050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 6.4 Donor network | The TIPHON network as a donor network is shown in Figure 3. Donor Network - TIPHON Recipient Network - SCN Originating Network Possible Transit Network(s) a b b c Call path a-b - onward routeing Call path a-(release)-c - QoR/dropback Call path c - ACQ Figure 3 For this role, if ACQ techniques are being used, there is n... |
050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 6.4.1 Onward routeing | If Onward routeing is employed then the TIPHON network should: 1) Determine that the call is to a ported number rather than one terminating on it; 2) Determine the routeing number for the ported number; 3) Deal with the routeing number. This could imply: a) Routeing the call to the appropriate egress point from the TIP... |
050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 6.4.2 QoR/Dropback | If QoR/Dropback is employed, then the TIPHON network should: 1) Determine that the call is to a ported number rather than one terminating on it; 2) Determine the routeing number for the ported number (Dropback only); 3) Release the call with an appropriate cause value (QoR or Dropback), and routeing number (Dropback on... |
050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 6.4.3 Additional comments | If the TIPHON networks are not directly interconnected and calls to ported numbers have to transit via the SCN, then the solution to be used should match with that deployed for the SCNs of the country in question. Therefore, in the UK and onward routeing approach with the routeing number being a 5xxxxx prefix would be ... |
050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 6.5 Recipient network | The TIPHON network as a recipient network is shown in Figure 4. Donor Network - SCN Recipient Network - TIPHON Originating Network Possible Transit Network(s) a b b c Call path a-b - onward routeing Call path a-(release)-c - QoR/dropback Call path c - ACQ Figure 4 The following comments apply to all number portability ... |
050a1ee5cb4899adf18a98ec80d78a34 | 101 858 | 7 Conclusions for Tiphon | Number portability is a requirement in many countries and if TIPHON networks support services for which number portability is required then they will be required to implement number portability. Where a TIPHON network is present in more than one country it may have to support more than one number portability solution. ... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 1 Scope | The present document identifies the issues of electronically steerable antennas. An electronically steerable antenna is used in Point-to-Multipoint (P-MP) or Multipoint-to-Multipoint (MP-MP) systems to cover different directions with narrow beams and high gain. |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 2 References | For the purposes of this Technical Report (TR) the following references apply: [1] EN 60950: "Safety of information technology equipment". [2] 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 thei... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 3 Definitions, symbols and abbreviations | |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: antenna: part of the transmitting or receiving system that is designed to transmit or receive electromagnetic radiation antenna directivity: ratio of the radiation intensity in a given direction from the antenna to the radiation intens... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: dBi Decibels relative to an isotropic source GHz GigaHertz |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: CS Central Station MTBF Mean Time Between Failures P-MP Point-to-MultiPoint RPE Radiation Pattern Envelope RS Repeater Station TS Terminal Station |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 4 Overview of electronically steerable antennas | |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 4.1 General properties | An antenna is the part of the radio equipment that is designed to radiate or receive electromagnetic waves. There are a number of ways to affect the performance of an antenna with electronics. In the present document only a certain type of electronically steerable antennas are discussed. These are antennas that can poi... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 4.2 Technology overview | There are a number of techniques to achieve electronically steerable antennas. They are here divided into three groups; phased array antennas, multiple beam antennas and other types of electronically steerable antennas. |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 4.2.1 Phased array antennas | Phased array antennas consist of several radiating elements. By exciting the elements with different amplitude and phase the radiation of the elements will combine constructively in some directions and destructively in other directions. A narrow beam can be created and pointed in different directions. |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 4.2.2 Multiple beam antennas | Multiple beam antennas typically utilize Butler matrix networks, lenses, reflectors or a combination. Essentially the antenna has several inputs and each input corresponds to the antenna pointing in a certain direction. The scanning is achieved by having a switch network that will switch between the inputs. In a lens o... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 4.2.3 Other types of electronically steerable antennas | There are other ways of creating electronically steerable antennas. A technique in so called adaptive antennas is to modify the baseband signal and upconvert it to high frequencies in a separate equipment chain for each antenna element. This type of steering is not considered in the present document. Another approach t... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5 Radiation pattern specific issues | |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5.1 Merged Radiation Pattern Envelope | A method on how to compare electronically steerable antennas with conventional antennas is outlined. For the purpose of standards the assumption that the electronically steerable antenna at any moment can point in any of the available pointing directions is made. If we merge the radiation pattern of all available point... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5.2 Boresight gain | The boresight directivity of an electronically steerable antenna can approach that of a same size fixed beam antenna. Antenna efficiency may however be significantly lower than for a conventional antenna due to losses in electronics. For a sector antenna the boresight gain is defined as the gain of the direction with t... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5.3 Scan sector | The scan sector refers to the angle sector which is declared to be covered by the antenna. A main beam can be pointed in different directions inside the scan sector. Some types of antennas (primarily multiple beam antennas) cannot be pointed continuously over the scan sector. In this coverage is achieved by having a di... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5.4 Sidelobes | Sidelobes of an electronically steerable antenna will depend on which pointing direction is active. We distinguish between sidelobes inside and outside the scan angle sector. Sidelobes outside the scan sector may interfere with other systems working outside the declared scan angle, and the requirements on levels of the... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5.5 Cross-polarization | Cross-polarization issues are similar to those encountered with other antennas. When designing an antenna it is often possible to employ symmetry features to reduce cross polarization. That is not possible for a steerable antenna which beams are not pointing along a line of symmetry in the antenna. Cross-polarization l... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 5.6 Elevation radiation pattern | Elevation radiation pattern may vary depending on pointing angle (see figure 3). The attainable gain will be lower at mainlobe overlap points for example. Figure 3: Illustration of merged radiation pattern envelope in both azimuth and elevation for a steerable antenna with 6 discrete pointing directions |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6 Electronics related issues | |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.1 Switching | The time to switch between different beam positions needs to be specified. Switch times are completely dependent of the technology used. Semiconductor switches and phase shifters can have switch times in the order of nanoseconds. Ferrite phase shifters can have switch times in the order of microseconds. It is important... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.2 Gain stability | Depending on what electronics the antenna contains, the gain stability of the antenna can be an issue. For example if the antenna contain amplifiers the amplification may be dependent on temperature. It may therefore be necessary to set up requirements on gain stability. ETSI ETSI TR 101 938 V1.2.1 (2002-06) 11 |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.3 Interfaces | There would typically be three interfaces when an electronically steerable antenna is connected to a system. They may all be on different connectors or two or all three may share the same connector. This should be agreed on between antenna manufacturer and user. When testing an electronically steerable antenna a manufa... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.4 Spectrum issues | Since electronically steerable antennas most often contain non-linear components, they may cause spectrum pollution. Hence requirements on spectrum must be addressed. The approach will be that systems employing steerable antennas should meet the same requirements as systems with conventional antennas. Two paths are ide... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.5 Noise | The noise performance needs to be considered for an electronically steerable antenna. If the antenna is passive it can be regarded as a similar conventional antenna with the same gain. If the antenna contains amplifiers, the noise figure of the antenna needs to be determined. |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.6 Input level range | The noise performance of the antenna will set a lower limit on the acceptable level of input signal on receive. On transmit the linearity of the antenna will set an upper limit. |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.7 Reciprocity | Some types of electronically steerable antennas are not reciprocal. That is they have different properties when transmitting and receiving. This can be due to what type of components are used in the switching or phase shifting devices. If an antenna is not reciprocal it should be declared and there should be two specif... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 6.8 Equipment failure issues | Multiple beam antennas have a predictable behaviour if the electronics fail. The pointing direction is governed by which input that is active. That may correspond to a certain input port of a Butler matrix or a certain feedpoint in a lens/reflector system. The antenna will not point in any direction that it cannot poin... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 7 Other issues | |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 7.1 Mechanical issues | An electronically steerable antenna has a narrower beam and typically presents a greater wind load, because of greater size, than a commensurate sector antenna. These two features require the antenna to be more mechanically stable than a sector antenna. In other regards the mounting issues of an electronically steerabl... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 7.2 Esthetical issues | An electronically steerable antenna is typically larger than the commensurate sector antenna. Some local authorities may impose restrictions on antenna installations with regard to the esthetical impact. For example it may be required that antennas below the roofline have a diameter of less than one meter. Electronical... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 8 Conformance tests | There are some new challenges when testing electronically steerable antennas. |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 8.1 Radiation pattern | For a multiple beam antenna each pointing direction can be measured in both azimuth and elevation and for both co- and cross-polarization. Essentially the measurements of each pointing direction are done in the same way as for a fixed beam antenna. If an antenna is declared not to be reciprocal it should be tested in b... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 8.2 Spectrum | The need for the emitted spectral density of the system including the antenna should be investigated. The manufacturer may be required to provide access points so that the radiated spectrum can be measured. For example in a multiple beam antenna employing reflector antennas the connector to the feed antennas can be the... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 9 Relation to existing standards | |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 9.1 Comparison to EN 302 085 | EN 302 085 [4] is a standard for point-to-multipoint antennas in the 3 GHz to 11 GHz range. It can serve as an example for how to relate electronically steerable antennas to standards for sector antennas. When an electronically steerable antenna is employed with a CS or RS system the antenna effectively replaces a CS s... |
be883abaed5d72d3fe27925ba6b76bbc | 101 938 | 10 Conclusions | Electronically steerable antennas applied to CS or RS have advantages compared to traditional sector antennas, among other things they can give sector coverage with a narrow beam. There are several techniques to build electronically steerable antennas. We have identified the properties that are common to antennas of ph... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 1 Scope | The present document is to investigate the interoperability of Private Integrated Services Networks (PISNs) and Internet Protocol (IP) networks, with a view to identifying possible scenarios for interoperation, problems that will have to be solved if particular scenarios are to be pursued further, and possible future s... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 2 References | For the purposes of this Technical Report (TR) the following references apply: [1] ECMA-133: "Private Integrated Services Network (PISN) - Reference Configurations for PISN Exchanges (PINX)". [2] ECMA-143: "Private Integrated Services Network (PISN) - Circuit Mode Bearer Services - Inter-Exchange Signalling Procedures ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3 Definitions | For the purposes of the present document, the following terms and definitions apply. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.1 Corporate telecommunication Network (CN) | Sets of equipment (Customer Premises Equipment and/or Customer Premises Networks) that are located at geographically dispersed locations and are interconnected to provide telecommunication services to a defined group of users. NOTE: A CN can comprise a PISN, a private IP network (intranet), or a combination of the two. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.2 Internet | A public IP network. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.3 Intranet | A private IP network. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.4 Internet Protocol (IP) | The protocol specified in RFC 791 (IP version 4) or in RFC 2460 (IP version 6). |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.5 IP network | A public or private network offering connectionless packet-mode services based on the Internet Protocol (IP) as the network layer protocol. NOTE: The Internet is the prime example of a public IP network. ETSI ETSI TR 101 913 V1.1.1 (2001-05) 10 |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.6 Private Integrated Services Network (PISN) | A private SCN. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.7 Private Integrated services Network eXchange (PINX) | See ECMA-133 [56]. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.8 Switched Circuit Network (SCN) | A public or private network offering connection-oriented circuit-mode telecommunication services. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 3.9 Tunnelling | A means of transporting protocol information between two entities that are interconnected by a network, without the need for that interconnecting network to comprehend the transported protocol information. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 4 Acronyms | AC Admission Control (functional entity) AH Authentication Header BICC Bearer-Independent Call Control CC Call Control (functional grouping) CLIP Calling Line Identification Presentation CLIR Calling/connected Line Identification Restriction CN Corporate telecommunication Network COLP COnnected Line identification Pres... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 5 Introduction | |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 5.1 Background | Private Integrated Services Networks (PISNs), based on 64 kbit/s-based Time Division Multiplexing (TDM) techniques, have for many years been the basis of corporate voice communications, and additionally have supported other services such as facsimile, video and data (circuit-switched and packet-switched). The technolog... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 5.2 Types of network | An IP network operates in packet mode, since information is sent in packets, when information is available, rather than as a continuous stream. Each packet is routed individually, rather than being switched in accordance with a pre-established connection. This makes an IP network a connectionless packet network. This c... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 5.3 Arrangements for interworking of SCNs and IP networks | Figure 2 illustrates possible interworking between the following types of network: - private switched circuit network (PISN); - public switched circuit network (public ISDN); - private IP network (intranet); - public IP network (Internet). Circuit network (connection-oriented, circuit-mode) IP network (connectionless, ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1 Architecture | In this clause the functional entities that in general are required to achieve multimedia communication over an IP network are derived and the way in which they relate to each other is represented diagrammatically. The resulting generic functional architecture can then be used as the basis for evaluating relevant exist... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.1 Media Processing and Packetization (MPP) functional entity | In order to transport a medium across an IP network between two users the medium has to be processed into a suitable form and packetized. At the receiving end it has to be de-packetized and processed back into its original form (or some other form suitable for onward transmission). For data these functions can be null ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.2 Resource Control (RC) functional entity | The functional architecture above does not include control functionality for establishing, maintaining and clearing down the transport of media. At any given time there can exist one or more unidirectional medium streams between two communicating users. Bi-directional transport of a given medium will involve two unidir... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.3 Session Control (SC) functional entity | Media transport between two users occurs within the context of a communication session between the two users. The normal method of session establishment is that one of the users requests a session with the other user, that other user being identified by some means, e.g., name, address. Establishment is supported by SC ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.5 Admission control (AC) functional entities | An AC functional entity grants admission to the IP network for the purpose of establishing a session and grants permission to use IP network bandwidth during that session. A SC-U functional entity consults an AC functional entity for this purpose. ETSI ETSI TR 101 913 V1.1.1 (2001-05) 19 |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.6 Identity resolution (IR) functional entity | IR functional entities convert user identities to addresses that the IP network can use for routing, i.e. IP addresses. IR functional entities are called upon by SC functional entities for this purpose. An IR functional entity may be able to resolve a given identity fully (to the address of the destination user), parti... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.7 Registrar (RGR) and registrant (RGT) functional entities | The relationship between a user identity and an IP address can be fixed. However, this means that the user must always use the same IP address and prevents the following: - user mobility between different terminals with different IP addresses; - terminal mobility between different sub-networks that use different IP add... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.8 Generic functional architecture (non-interworking) | With all of the functional entities identified above, the functional architecture is as shown in figure 7. MPP User User IP network RC-U SC-U SC-P RC-P MPP RC-U SC-U SC-R IR IR AC RGT RGR AC RGT RGR Key: RGT – registrant RGR – registrar AC – admission control IR – identity resolution SC-U – session control – user SC-P ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.10 Generic functional architecture for interworking with an SCN | The generic functional architecture at either side of the IP network is modified as shown in figure 9 when interworking with an SCN. In the figure the SCN is represented by two functional entities: SCN switching (representing the collective switching capabilities of the SCN) and SCN control (representing the collective... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.1.12 Simple terminals | As has already been shown (see clause 6.1.9), user endpoints comprise a number of functional entities (i.e., MPP, RGT, SC-U, RC-U), reflecting the fact that a user endpoint acts as the interface between the user and the packet environment. An alternative view of a user endpoint is that it performs interworking between ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.2 Naming and addressing | For an IP network, the basic form of addressing is by means of IP addresses. At present this is almost predominantly IPv4 addresses comprising 4 octets. Longer IPv6 addresses are expected to be introduced eventually. In many cases, for convenience of the user, names are used as aliases for IP addresses, because names c... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.3 Security | Present day IP packet-based networks do not in general provide end-to-end security services. Therefore, when interconnecting a secure private switched circuit network (SCN) to an IP network, there is an increased potential for risk of attack by an intruder. Simply by attaching a network monitor that is SCN protocol cap... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.4 Quality of service (QoS) | Quality of service is the collective effect of service performance factors, which determines the degree of satisfaction obtained by a user of the service. Traditional SCNs offer good quality speech transmission, which is based upon the fact that SCNs had a relatively slow evolution and have always been optimized for se... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 6.5 Mobility | Three types of mobility in networks are recognized: - User mobility is the ability for a user to maintain the same user identity on different terminals or terminal types. - Terminal mobility is the ability for a terminal to change location and network point of attachment and still be able to communicate. - Service mobi... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.1 Overview | Important sources for existing and emerging standards for multimedia communication over a packet network are the ITU-T and the IETF. Figure 15 gives the generic functional architecture for multimedia communication over IP networks, including interworking with an SCN, showing most relevant interfaces. To SCN switching T... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2 The ITU-T H.323 family of recommendations | ITU-T Recommendation H.323 [24] (Packet-based Multimedia Communications Systems) is an umbrella recommendation that specifies protocols and procedures for multimedia communications over packet networks, including IP networks. ITU-T Recommendation H.323 itself refers to other ITU-T Recommendations, e.g., ITU-T Recommend... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2.1 Functional architecture | The main H.323 entities are endpoints (endstations, gateways or MCUs) and gatekeepers. For the case where one endpoint is an endstation (terminal) and the other is a gateway to an SCN, the allocation of functional entities to H.323 entities is as shown in figure 16. Gateway Gatekeeper Gatekeeper End-station MPP User IP... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2.2 Naming and addressing | In accordance with H.323 when applied to IP networks, addressing is by means of IP addresses. However, in H.323 the concept of aliases exists, whereby an addressable entity can have one or more other forms of identification in addition to an IP address. An alias can act as an address, but more often acts as a name. Exa... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2.3 Supplementary services | Supplementary services for use with H.323 in an IP network are specified in ITU-T Recommendation H.450.x series of recommendations [25] to [33]. ITU-T Recommendation H.450.1 [25] specifies the generic functional protocol that is used by other recommendations in the series. The following supplementary service recommenda... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2.4 Security | H.323 VoIP security procedures are outlined in ITU-T Recommendation H.235 [65]. The recommendation identifies a number of security services, including authentication, integrity, and confidentiality, which are intended to counter the primary threats of eavesdropping and media stream diversion. Confidentiality is also re... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2.5 Quality of service | H.323 is concerned with multimedia communications services over packet based networks that do not necessarily provide a guaranteed Quality of Service (QoS). In order to fulfil the QoS requirements of real-time video and audio streams, H.323 recommends the use of transport level resource reservation mechanisms. Such tra... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.2.6 Mobility | H.323 inherently supports user mobility through the use of gatekeepers and the mapping of user identity (e.g., in the form of a telephone number) to IP address representing the user's current location. By registering with its gatekeeper, a user can make and receive calls in principle from any terminal at any location. ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.3 Other ITU-T standards | |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.3.1 H.248 | ITU-T Recommendation H.248 [21] (Gateway Control Protocol) is complementary to ITU-T Recommendation H.323. [24] It defines the protocols used between elements of a physically decomposed multimedia gateway, used in accordance with the architecture as specified in ITU-T Recommendation H 248 [24]. is the result of co-oper... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.3.2 BICC | Bearer-Independent Call Control (BICC) is a protocol being developed by ITU-T Study Group 11 as an adaptation of SS7 ISUP. Initially developed for controlling bearers provided by ATM networks, work is now being extended to control bearers provided by IP networks. BICC itself runs in an existing signalling network. As f... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4 IETF specifications for IP telephony | Different protocols related to IP telephony are emerging from the IETF. Logically, these individual protocols can be used to create a complete framework for multimedia communication over IP networks. The difference from ITU-T Recommendation H.323 [66] is that there is no umbrella specification that formally glues toget... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.1 Functional architecture | The main entities defined in relevant IETF protocols are SIP proxy servers, SIP redirect servers, location servers, SIP registrars and endpoints (endstations, gateways) containing SIP user agents. The mapping of SIP entities onto functional entities of the generic functional architecture is as shown in figure 17. To SC... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2 Main protocols | |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2.1 Real-time Transport Protocol (RTP) | The Real time Transport Protocol (RFC 1889 [39]) provides end-to-end delivery services for data with real-time characteristics, such as interactive audio and video. Those services include payload type identification, sequence numbering, time-stamping and delivery monitoring. Applications typically run RTP on top of UDP... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2.2 Session Initiation Protocol (SIP) | The Session Initiation Protocol is a session control signalling protocol for IP telephony and multimedia conferencing. SIP can establish, modify and terminate phone calls or multimedia sessions. It has been developed within the IETF MMUSIC (Multiparty Multimedia Session Control) working group, and is now a Proposed Sta... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2.3 Session Description Protocol (SDP) | SDP (RFC 2327 [44]) is used to describe multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation. Although not mandated, SDP is the assumed candidate for use with SIP. Contrary to ITU-T Recommendation H.245 [20] , SDP is not intended for negotiat... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2.5 Telephony Routing Information Protocol (TRIP) | The Telephony Routing Information Protocol (TRIP) is being specified by the IETF IPTEL group. TRIP is a policy driven inter-administrative domain protocol for advertising the reachability of telephony destinations between location servers, and for advertising attributes of the routes to those destinations. TRIP's opera... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2.6 Media Gateway Control Protocol (MEGACOP) | MEGACOP defines protocols used between elements of a physically decomposed multimedia gateway and is the result of co-operative work between ITU-T Study Group 16 and the IETF MEGACO working group. See clause 7.3.1. |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.2.7 Stream Control Transport Protocol (SCTP) | Work in the IETF SIGTRAN group has produced a transport protocol suitable for carrying signalling, in particular taking into account the high demands of SS7. RFC 2960 specifies a Stream Control Transport Protocol (SCTP). Although it has a number of possible applications, the initial aim is to fulfil requirements of int... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.3 Naming and addressing | In SIP, users are identified and addressed by SIP URLs (such as sip:jack@company.com). Calls to this address must traverse SIP servers on the network, much like email traverses message transfer agents (MTA's), eventually arriving at the current location for this user. More precisely, SIP uses an email-like identifier o... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.4 Supplementary services | Assuming a high degree of decentralization, many supplementary services are enabled by basic SIP (RFC 2543 [52]). Without the need for further standardization, many supplementary services can be implemented in SIP endstations. A certain set of services however, need to be implemented in a network component, such as a S... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.5 Security | The SIP specification includes capabilities for encryption and authentication of SIP messages. These mechanisms can protect against unauthorized use of the signalling information contained in SIP and SDP messages. Different, complementary forms of security are supported. End-to-end encryption of SIP message body and ce... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.6 Quality of service | Different mechanisms for Quality of Service control and measurement are available, including: - RTP control Protocol (RTCP) defined in RFC 1889 [39]. RTCP provides feedback on quality of transmission. - End-to-end QoS reservations based on for example the Resource reSerVation Protocol (RFC 2205 [40]). - Differentiated ... |
c6ea5d8244134a269d02b41d6fbd6536 | 101 913 | 7.4.7 Mobility | SIP transparently supports user mobility by name mapping and by proxying and redirecting requests to the user's current location. Based on the use of a unique personal identity and the ability of SIP-users to register their current location, end users can originate and receive calls and access subscribed telecommunicat... |
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