Content for TS 48.006 Word version: 18.0.0

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1 Scope p. 6

The present document is split into four parts, clauses 4 to 6 dealing with the MTP, clause 6a dealing with M3UA/SCTP, clause 7 dealing with interface functions towards higher layers and clauses 8 to 10 dealing with the SCCP and its use.

The MTP provides a mechanism giving reliable transfer of signalling messages. Clauses 4 to 7 of the present document deal with the subset of the MTP that can be used between an BSS and an MSC, which is compatible with a full MTP.

The M3UA/SCTP provides a mechanism giving reliable transfer of signalling messages over an IP network.

The SCCP is used to provide a referencing mechanism to identify a particular transaction relating to for instance a particular call. Clauses 8 to 10 identify the SCCP subset that should be used between a BSS and an MSC. The SCCP can also be used to enhance the message routing for (for instance) operations and maintenance information.

2 References p. 6

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. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.

[1]

TR 21.905: "Vocabulary for 3GPP Specifications".

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TS 44.006: "Mobile Station - Base Station System (MS - BSS) interface Data Link (DL) layer specification".

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TS 44.018: "Mobile radio interface layer 3 specification; Radio Resource Control Protocol".

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TS 48.008: "Mobile Switching Centre - Base Station System (MSC-BSS) interface; Layer 3 specification".

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[58]

ITU-T Recommendation Q.702: "Signalling data link".

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ITU-T Recommendation Q.703: "Signalling link".

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ITU-T Recommendation Q.704: "Signalling network functions and messages".

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ITU-T Recommendation Q.707: "Testing and maintenance".

[62]

ITU-T Recommendation Q.711: "Functional description of the signalling connection control part".

[63]

ITU-T Recommendation Q.712: "Definition and function of signalling connection control part messages".

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ITU-T Recommendation Q.713: "Signalling connection control part formats and codes".

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ITU-T Recommendation Q.714: "Signalling connection control part procedures".

[66]

TS 23.003: "Numbering, addressing and identification".

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ANSI T1.110-1999: "Signaling System No.7; General Information".

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ANSI T1.111-2000: "Signalling System No. 7; Message Transfer Part".

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ANSI T1.112-1996: "Signalling System No. 7; Signalling Connection Control Part Functional Description".

[70]

TIA/EIA/IS-104-A: "Personal Communications Service Descriptions for 1 800 MHz".

[71]

ITU-T Recommendation Q.701: "Functional description of the message transfer part (MTP) of Signalling System No. 7".

[72]

RFC 2960(10/2000): "Stream Control Transmission Protocol".

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RFC 3332(09/2002): "Signalling System 7 (SS7) Message Transfer Part 3 (MTP3) - User Adaptation Layer (M3UA)".

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RFC 1661(07/1994), STD 51: "The Point-To-Point Protocol (PPP)".

[75]

RFC 1662(07/1994), STD 51: "PPP in HDLC-like Framing".

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RFC 2507(02/1999): "IP header compression".

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RFC 1990(07/1994): "The PPP Multilink Protocol (MP)".

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RFC 2686(09/1999): "The Multi-Class Extension to Multi-Link PPP".

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RFC 2509(02/1999): "IP Header Compression over PPP".

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RFC 2474 (12/1998): "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers".

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RFC 3309: "SCTP Checksum Change".

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RFC 791 (09/1981): "Internet Protocol".

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RFC 2460: "Internet Protocol, Version 6 (Ipv6) Specification".

[84]

TS 29.202: "SS7 Signalling Transport in Core Network; Stage 3"

3 Definitions and abbreviations p. 9

3.1 Definitions p. 9

For the purposes of the present document, the following terms and definitions apply:

E1:

link employs 32 Pulse Code Modulation signals (timeslots) at 64 kbits/s. The 32 timeslots consist of 30 voice (or signalling) channels and 2 common signalling channels. The output bit rate is 2048 Mbits/s.

T1:

link employs 24 Pulse Code Modulation signals (timeslots) at 64 kbits/s. (T1 interface can alternatively use signalling at 56 kbits/s). The output bit rate is 1544 Mbits/s. (A frame consists of 193 bits, (8 x 24) + 1, as one bit is used for synchronization. The frame repeats 8,000 times per second.).

3.2 Abbreviations p. 9

For the purposes of the present document, the abbreviations given in TR 21.905 apply.

4 Field of application p. 9

The present document is applicable to the signalling between radio subsystems (BSS) and mobile switching centres (MSCs) in GSM PLMNs. It provides a minimum set of MTP, or in the case of IP-based signalling transport - M3UA and SCTP, requirements that may be implemented at a BSS or MSC, whilst maintaining compatibility with the implementation of a full specification of the MTP (M3UA/SCTP).
For MTP signalling transport usage, the Technical Specification defines the interface at the 64 kbits/s boundary to the BSS or MSC and applies primarily for digital access arrangements, the use of analogue arrangements isan option for PLMN operator. Also, the Technical Specification defines the interface at the 56 kbits/s boundary to the BSS or MSC for T1 links.
The security of signalling links is a PLMN operator concern , however it is recommended that in the case where more than one multiplex system is required and security reasons dictate the use of a multiple link linkset, then each signalling link should be assigned in a different multiplex system. It is however noted that this is of little benefit if diversity of routing of the multiplexes is not used.
Both associated and quasi-associated modes of signalling between the BSS and the MSC are allowed. In case of quasi-associated mode the STP functionality is provided outside the BSS. Future evolution or economic reasons applicable to the interface may however make the use of STP working at the BSS attractive, in which case some of the simplifications in this paper will not apply.
A variety of information types may be supported by the signalling system, e.g. relating to circuit switched call control and packet communication. These are fully defined in the service series of Technical Specifications (the 3GPP TS 02.xx series and in [70] for PCS 1900).
For E1 link usage, the ITU-T recommendations concerning the MTP shall be taken as being requirements unless covered by a statement in the present document.
For T1 link usage, the ANSI recommendations concerning the MTP [68] shall be taken as being requirements unless covered by a statement in the present document.
For IP-based signaling transport usage, TS 29.202 shall be taken as being requirements unless covered by a statement in the present document.

5 Functional content p. 9

The functional requirements are as follows:

the network call control functions are as specified in TS 48.008 and TS 44.018;
the minimum set of Message Transfer Part functions are specified in Blue Book ITU-T Recommendations Q.702, Q.703, Q.704 and Q.707, with the qualifications specified in the present document;
The functions are specified in ANSI T1.111 [68] for T1 links.
the additional interface functions required for the proper operation of the layer 3 control functions in combination with the Message Transfer Part, or in the case of IP-based signalling transport - M3UA and SCTP, functions, are specified in clause 7 of the present document.
the minimum set of Message Transfer Part 3 - User Adaptation (M3UA) functions are specified in TS 29.202.