1、w GSM GSM 08.56 December 1996 Version 5.0.0 Source: ETSI TC-SMG Reference: TS/SMG-O30856Q ICs: 33.020 Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM) GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS Digital cellular telecommunications system; Base Station
2、Controller - Base Transceiver Station (BSC - BTS) interface; Layer 2 specification (GSM 08.56) ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE Off ice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
3、X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariatQetsi.fr Tel.: +33 4 92 94 42 O0 - Fax: +33 4 93 65 47 16 Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media.
4、Q European Telecommunications Standards Institute 1996. All rights reserved. STD-ETSI GSM 08.5b-ENGL 177b m 3400855 0353038 T49 m Page 2 GSM 08.56 version 5.0.0: December 1996 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or ot
5、herwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title page. STD-ETSI GSM 08.5b-ENGL L77b = 3400855 0153039 785 Page 3 GSM 08.56 version 5.0.0: December 1996 Contents Foreword . 5 1 Scope 7 2 Norm
6、ative references 7 3 Definitions and abbreviations 8 4 General description . 8 5 Functional contents . 9 6.1.12 6.1.13 6.1.14 6.1.15 6 LAPD functions 9 Exceptions and modifications 10 6.1.2 CommandResponse field bit (C/R) 10 6.1.3 Service Access Point Identifier (SAPI) 10 6.1.4 TE1 for point-to-poin
7、t data link connection . 10 6.1.5 Commands and responses . 10 6.1.6 Exchange identification (XID) commandhesponse . 10 6.1.7 MDL-XID 10 6.1.8 6.1.9 MPH-ACTIVATE, MPH-DEACTIVATE an MPH-INFORMATION . 11 6.1.10 Priority indicator . 11 6.1.1 1 Terminal Endpoint Identifier FEI) management procedures 11 6
8、.1.1 1.1 General 11 6.1.1 1.2 TE1 assignment procedure 11 6.1.1 1.3 TE1 identity verify procedure 13 6.1.1 1.4 Formats and codes 13 Automatic negotiation of data link layer parameters . 14 Establishment procedures . 14 N(S) sequence error 14 List of system parameters . 14 6.1 PH-DATA, PH DEACTIVATE
9、and PH-ACTIVATE 11 6.1.15.1 Timer T200 15 6.1.1 5.2 Maximum number of retransmissions (N200) . 15 6.1.15.3 Maximum number of octets in an information field (N201) 15 6.1.15.4 Maximum number of transmission of the TE1 identity request message (N202) . 15 6.1.15.5 Maximum number of outstanding frames
10、(K) 15 6.1.1 5.6 Timer T201 15 6.1.1 5.7 Timer T202 15 6.1.1 5.8 Timer T203 15 6.1.16 Data link layer monitor function . 15 6.1.17 Miscellaneous 15 History 16 STD-ETSI GSM 08-5b-ENGL L97b m 3400855 0353040 bT7 m Page 4 GSM 08.56 version 5.0.0: December 1996 Blank page STD-ETSI GSM 08-5b-ENGL L77b m
11、3400855 0153041 533 m Page 5 GSM 08.56 version 5.0.0: December 1996 Foreword This Global System for Mobile communications Technical Specification (GTS) has been produced by the Special Mobile Group (SMG) Technical Committee (TC) of the European Telecommunications Standards Institute (ETSI). This GTS
12、 specifies the link layer used for signalling on the A-bis interface between Base Station Controller (BSC) and Base Transceiver Station (BTS) within the digital cellular telecommunications system. The contents of this GTS are subject to continuing work within TC-SMG and may change following formal T
13、C-SMG approval. Should TC-SMG modify the contents of this GTS it will then be republished by ETSI with an identifying change of release date and an increase in version number as follows: Version 5.x.y where: y the third digit is incremented when editorial only changes have been incorporated in the s
14、pecification; x the second digit is incremented for all other types of changes, .e. technical enhancements, corrections, updates, etc. The specification from which this GTS has been derived was originally based on CEPT documentation, hence the presentation of this GTS may not be entirely in accordan
15、ce with the ETSVPNE rules. STDSETSI GSM 08.5b-ENGL L99b 3400855 0353042 47T Page 6 GSM 08.56 version 5.0.0: December 1996 Blank page STD-ETSI GSM 08*.5b-ENGL 177b m 3400855 0153093 30b m Page 7 GSM 08.56 version 5.0.0: December 1996 1 Scope This Global System for Mobile communications Technical Spec
16、ification (GTS) specifies the link layer used for signalling on the A-bis interface between Base Station Controller (BSC) and Base Transceiver Station (BTS). The use and general aspects of the A-bis interface are described in GSM 08.51 and the interface aspects in GSM 08.52. The Link Access Procedur
17、e on the D-channel (LAPD) specification used on the A-bis interface in the GSM PLMN is a subset of the ETS300125 which in turn has less options than the CCITT Recommendation Q.921. This description contains first the protocol definitions and second the services provided by the layer 2 to the layer 3
18、. 2 Normative references This GTS incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
19、of these publications apply to this GTS only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies. 11 1 131 i41 151 181 i91 o1 11 21 i 31 GSM O1 .O4 (ETR 350): “Digital cellular telecommunications system (Phase 2+); Abbre
20、viations and acronyms“. GSM 08.51 : “Digital cellular telecommunications system; Base Station Controller - Base Transceiver Station (BSC - BTS) interface; General aspects“. GSM 08.52: “Digital cellular telecommunications system; Base Station Controller - Base Transceiver Station (BSC - BTS) interfac
21、e; Interface principles“. GSM 12.00 (ETS 300 61 2-1): “Digital cellular telecommunications system (Phase 2); Objectives and structure of Network Management (NM)“. GSM 12.01 (ETC 300 612-2): “Digital cellular telecommunications system (Phase 2); Common aspects of GSM Network Management (NM)“. GSM 12.
22、07 (ETS 300 61 2-3): “Digital cellular telecommunications system (Phase 2); Operations and performance management“. GSM 12.02 (ETS 300 61 3): “Digital cellular telecommunications system (Phase 2); Subscriber, Mobile Equipment (ME) and services data administration“. GSM 12.03 (ETS 300 61 4): “Digital
23、 cellular telecommunications system (Phase 2); Security management“. GSM 12.04 (ETS 300 61 5): “Digital cellular telecommunications system (Phase 2); Performance data measurements“. GSM 12.05 (ETS 300 61 6): “Digital cellular telecommunications system (Phase 2); Subscriber related event and call dat
24、a“. GSM 12.06 (ETS 300 61 7): “Digital cellular telecommunications system (Phase 2); GSM Network change control“. GSM 12.1 1 (ETS 300 619): “Digital cellular telecommunications system (Phase 2); Maintenance of the Base Station System (BSS)“. GSM 12.20 (ETS 300 622): “Digital cellular telecommunicati
25、ons system (Phase 2); Network Management (NM) procedures and messages“. STD-ETSI GSM 08.5b-ENGL 177b 3400855 0353044 242 D Page 8 GSM 08.56 version 5.0.0: December 1996 11 41 i 51 i 71 GSM 12.21 (ETS 300 623): “Digital cellular telecommunications system (Phase 2); Network Management (NM) procedures
26、and message on the A-bis interface“. GSM 12.22 (ETS 300 624): “Digital cellular telecommunications system (Phase 2); Interworking of GSM Network Management (NM) procedures and messages at the Base Station Controller (BSC)“. CCITT Recommendation (2.921 : “Integrated services digital network (ISDN) us
27、er-network interface - Data link layer specification“. ETS 300 125: “Integrated Services Digital Network (ISDN); User-network interface data link layer specification Application of CCITT Recommendations Q.920A.440 and Q.921/1.441 I. 3 Definitions and abbreviations The following abbreviations and acr
28、onyms are used in this GTS. Ai BCF BSC BTS C/R GSM EML LAPD MS N(S) O - layer 2 management. signalling (including Short Message Service (SMS) information); For each of these categories the BSC may have one or more layer 2 links to every TRX and BCF. The signalling links over the A-bis interface are
29、addressed to the different units by Terminal Endpoint Identifiers (TEI). The same unit will normally have more than one functional entity. The logical links between different functional entities are identified by functional addresses, the Service Access Points Identifier (SAPI). Figure 1 shows the a
30、rchitectural model with different layer 2 links. STD-ETSI GSM 08.5b-ENGL L77b m 3400855 0353045 387 m Page 9 GSM 08.56 version 5.0.0: December 1996 RSL SAPI = O TRX OML SAPI = 62 2ML SAPI = 63 RSL SAPI = O OML SAPI = 62 2ML SAPI = 63 TRX I - A number of logical links may be multiplexed on each physi
31、cal link. The same layer 2 logical link may not be distributed over more than one physical link. TE12 TE13 AYER 2 TE1 AANAGE- AENT I I I Figure 1 : An example of Logical Layer 2 links supported by three permanent and one semipermanent links 5 Functional contents The basic functional content of the l
32、ayer 2 protocol is: transparent layer 2 links and time fill; point-to-point dedicated layer 2 links addressing both physical entities and functional entities; point-to-multipoint addressed links used for layer 2 management; basic functions for TE1 assignment and management; basic priority functions;
33、 basic supervision of links when not carrying traffic; sequence control; transmission error control; control of errors not recoverable by retransmission. 6 LAPD functions The LAPD functions as specified in ETS 300 125 are applicable. However, the exceptions and modifications specified in the remaind
34、er of this specification shall be used. STD-ETSI GSM 08-5b-ENGL L77b m 3Li00855 O15304b 015 m Page 10 GSM 08.56 version 5.0.0: December 1996 value O - 63 64 - 126 6.1 Exceptions and modifications TE1 assignment for fixed TRX and BCF addresses. EI assignment for additional, TRX or BCF addresses. In t
35、he fallowing headlines from ETS 300 125 are kept and references are made to the corresponding subclause of ETS 300 125. 6.1.2 CommandlResponse field bit (C/R) (Refer to ETS 300 125, part 2, subclause 3.3.2.) In GSM PLMNs BSC represents the network side and TRWBCF the user side of the interface. 6.1.
36、3 Service Access Point Identifier (SAPI) (Refer to ETS 300 125, part 2, subclause 3.3.3.) The SAPI values for the A-bis interface are as listed in table 1. Table 1 : Allocation of SAPI values and priority classes 6.1.4 TE1 for point-to-point data link connection (Refer to ETS 300 125, part 2, subcla
37、use 3.3.4.2.) The remaining Terminal Endpoint Identifier (TEI) values are used for the point-to-point data link connections associated with the addressed Service Access Point (SAP). The range of TE1 values shall be allocated as shown in table 2. Table 2: Allocation of TE1 values I TI I User type I N
38、OTE: A BCF is given a separate layer 2 link only if it is not integrated with a TRX. 6.1.5 Commands and responses (Refer to ETS 300 125, part 2, subclause 3.6.1.) The XID command and response are not used. 6.1.6 Exchange identification (XID) commandresponse (Refer to ETC 300 125, part 2, subclause 3
39、.6.1 2.) This functionality is not used. 6.1.7 MD L-XI D (Refer to ETS 300 125, part 2, subclause 4.1.1.9.) This functionality is not used. Page 11 STD-ETSI GSM 08.5b-ENGL L77b 3400855 0353047 T51 GSM 88.56 version 5.0.0: December1996 6.1.8 PH-DATA, PH DEACTIVATE and PH-ACTIVATE (Refer to ETS 300 12
40、5, part 2, subclauses 4.1.1.10 - 4.1.1.12). This functionality is not relevant. 6.1.9 MPH-ACTIVATE, MPH-DEACTIVATE an MPH-INFORMATION (Refer to ETS 300 125, part 2, subclauses 4.1.1.13 - 4.1.1.1 5.) This functionality is not relevant. 6.1.1 O Priority indicator (Refer to ETS 300 125, pari 2, subclau
41、se 4.1.3.1 .) The different SAPIs are given the priority classes as listed in table 1 when contending (with priority one as the highest). 6.1.1 1 Terminal Endpoint Identifier (TEI) management procedures (Refer to ETS 300 125, pari 2, subclause 5.3.) Due to the special assignment functions needed on
42、the A-bis interface there are modifications and additions to the assignment procedures. The rest of subclause 5.3 in ETS 300 125, part 2, is kept if not stated otherwise. 6.1.1 1.1 General (Refer to ETS 300 125, part 2, subclause 5.3.1.) TE1 management for A-bis interface is based on the following p
43、rocedural means: - - the TE1 check procedures; - the TE1 remove procedures; - The TE1 management needs procedures to check the used TE1 values and procedures for reaction in situation where more than one TRX equipment uses the same TE1 value. In addition to the fixed values it shall be possible to u
44、se additional TE1 value to the same TRX equipment and thus increase the signalling capacity. a Subset of the TE1 assignment procedures; an additional TE1 assignment procedure. 6.1.1 1.2 TE1 assignment procedure (Refer to ETS 300 125, part 2, subclause 5.3.2.) The TE1 assignment procedure used on the
45、 A-bis interface has some additions to the automatic TE1 assignment procedure specified in ETS 300 125, part 2. To facilitate the configuration control in the BSC each TRX will have a fixed TE1 and possibly get access to one or more additional TEls assigning physical channeldlayer 2 links. The layer
46、 2 links may all be turned on and off according to the normal automatic TE1 assignment scheme but the TRX may only request identified TE1 values which is (semi-) permanently programmed or programmed by operation and maintenance messages. In GSM the reference number Ri is not used. It is only misoper
47、ation situations resulting from double failures that could be prevented/solved faster by this parameter. The marginal advantage is not supposed to motivate the application of a random generator and the checking procedure. The subset of the automatic assignment procedure applicable for the first laye
48、r 2 link to a TRX shall have the following modifications to ETS 300 125, pari 2: - the identity request shall have an Ai value in the range 0-63 identifying the TE1 value which is requested for activation; STD*ETSI GSM 08-5b-ENGL L99b D 3400855 OL53Oii8 778 Page 12 GSM 08.56 version 5.0.0: December
49、1996 - on reception of the identity request message the BSC will check that the requested TE1 may be used from the configurations aspects and then perform a normal TE1 check procedure to prevent a double assignment; - if the TE1 request is accepted an identity assigned message with the requested TE1 number is received by TRX before the expiry of timer T202; - a successful assignment procedure is shown in figure 2. T T202 c Ident it y request (Ai ) Identity check request (Ai Normal check I ide nt it y I I I procedure I I No answer Ident
