1、 ETSI TS 148 056 V14.0.0 (2017-04) Digital cellular telecommunications system (Phase 2+) (GSM); Base Station Controller - Base Transceiver Station (BSC - BTS) interface; Layer 2 specification (3GPP TS 48.056 version 14.0.0 Release 14) TECHNICAL SPECIFICATION GLOBAL SYSTEM FOR MOBILE COMMUNICATIONSRE
2、TSI ETSI TS 148 056 V14.0.0 (2017-04)13GPP TS 48.056 version 14.0.0 Release 14Reference RTS/TSGR-0648056ve00 Keywords GSM ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucra
3、tif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice The present document can be downloaded from: http:/www.etsi.org/standards-search The present document may be made available in electronic versions and/or in print. The content of any electronic and/or print versions of the pr
4、esent document shall not be modified without the prior written authorization of ETSI. In case of any existing or perceived difference in contents between such versions and/or in print, the only prevailing document is the print of the Portable Document Format (PDF) version kept on a specific network
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7、 authorized by written permission of ETSI. The content of the PDF version shall not be modified without the written authorization of ETSI. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2017. All rights reserved. DECTT
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9、sociation. ETSI ETSI TS 148 056 V14.0.0 (2017-04)23GPP TS 48.056 version 14.0.0 Release 14Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for
10、 ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (https
11、:/ipr.etsi.org/). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essent
12、ial to the present document. Foreword This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or GSM identities. These should be interpret
13、ed as being references to the corresponding ETSI deliverables. The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under http:/webapp.etsi.org/key/queryform.asp. Modal verbs terminology In the present document “shall“, “shall not“, “should“, “should not“, “may“, “need not“,
14、“will“, “will not“, “can“ and “cannot“ are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). “must“ and “must not“ are NOT allowed in ETSI deliverables except when used in direct citation. ETSI ETSI TS 148 056 V14.0.0 (2017-04)33
15、GPP TS 48.056 version 14.0.0 Release 14Contents Intellectual Property Rights 2g3Foreword . 2g3Modal verbs terminology 2g3Foreword . 4g31 Scope 5g32 References 5g33 Definitions and abbreviations . 6g34 General description. 6g35 Functional contents 7g36 LAPD functions 7g36.1 Exceptions and modificatio
16、ns. 7g36.1.1 Void 7g36.1.2 Command/Response field bit (C/R) 7g36.1.3 Service Access Point Identifier (SAPI) . 7g36.1.4 TEI for point-to-point data link connection 8g36.1.5 Commands and responses . 8g36.1.6 Exchange identification (XID) command/response 8g36.1.7 MDL-XID . 8g36.1.8 PH-DATA, PH DEACTIV
17、ATE and PH-ACTIVATE 8 g36.1.9 MPH-ACTIVATE, MPH-DEACTIVATE an MPH-INFORMATION 8g36.1.10 Priority indicator . 9g36.1.11 Terminal Endpoint Identifier (TEI) management procedures . 9g36.1.11.1 General 9g36.1.11.2 TEI assignment procedure . 9g36.1.11.3 TEI identity verify procedure 11g36.1.11.4 Formats
18、and codes. 11g36.1.12 Automatic negotiation of data link layer parameters 11g36.1.13 Establishment procedures . 11g36.1.14 N(S) sequence error 11g36.1.15 List of system parameters . 11g36.1.15.1 Timer T200 . 12g36.1.15.2 Maximum number of retransmissions (N200) 12g36.1.15.3 Maximum number of octets
19、in an information field (N201) . 12g36.1.15.4 Maximum number of transmission of the TEI identity request message (N202) 12g36.1.15.5 Maximum number of outstanding frames (K) . 12g36.1.15.6 Timer T201 . 12g36.1.15.7 Timer T202 . 12g36.1.15.8 Timer T203 . 12g36.1.16 Data link layer monitor function .
20、13g36.1.17 Miscellaneous . 13g3Annex A (informative): Change History 14g3History 15g3ETSI ETSI TS 148 056 V14.0.0 (2017-04)43GPP TS 48.056 version 14.0.0 Release 14Foreword This Technical Specification has been produced by the 3rd Generation Partnership Project (3GPP). The contents of the present do
21、cument are subject to continuing work within the TSG and may change following formal TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an identifying change of release date and an increase in version number as follows: Version x.y.z wher
22、e: x the first digit: 1 presented to TSG for information; 2 presented to TSG for approval; 3 or greater indicates TSG approved document under change control. y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates, etc. z the third digit is i
23、ncremented when editorial only changes have been incorporated in the document. ETSI ETSI TS 148 056 V14.0.0 (2017-04)53GPP TS 48.056 version 14.0.0 Release 141 Scope The present document specifies the link layer used for signalling on the A-bis interface between BSC and BTS. The use and general aspe
24、cts of the A-bis interface are described in 3GPP TS 48.051 and the interface aspects in 3GPP TS 48.052. The Link Access Procedure on the D-channel (LAPD) specification used on the A-bis interface in the GSM PLMN is a subset of the EN 300 125 which in turn has less options than the CCITT Recommendati
25、on Q.921. This description contains first the protocol definitions and second the services provided by the layer 2 to the layer 3. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References are either speci
26、fic (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-specif
27、ic reference implicitly refers to the latest version of that document in the same Release as the present document. 1 3GPP TS 21.905: “Vocabulary for 3GPP Specifications“. 2 3GPP TS 48.051: “Base Station Controller - Base Transceiver Station (BSC - BTS) interface; General aspects“. 3 3GPP TS 48.052:
28、“Base Station Controller - Base Transceiver Station (BSC - BTS) interface; Interface principles“. 4 Void. 5 Void. 6 Void. 7 Void. 8 Void. 9 Void. 10 Void. 11 Void. 12 Void. 13 Void. 14 Void. 15 Void. 16 Void. 17 Void. 18 Void. ETSI ETSI TS 148 056 V14.0.0 (2017-04)63GPP TS 48.056 version 14.0.0 Rele
29、ase 1419 CCITT Recommendation Q.921: “Integrated services digital network (ISDN) user-network interface - Data link layer specification“. 20 EN 300 125: “Integrated Services Digital Network (ISDN); User-network interface data link layer specification Application of CCITT Recommendations Q.920/I.440
30、and Q.921/I.441“. 3 Definitions and abbreviations Abbreviations used in the present document are listed in 3GPP TS 21.905. 4 General description The following information categories are supported by the procedures of this layer 2 Recommendation: - signalling (including Short Message Service (SMS) in
31、formation); - operation and maintenance; - layer 2 management. 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 addressed to the different units by Terminal Endpoint Identifiers (TEI). The same unit will n
32、ormally 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 architectural model with different layer 2 links. A number of logical links may be multiplexed
33、 on each physical link. The same layer 2 logical link may not be distributed over more than one physical link. _ | _ | | | | | | | | _ | _ _ | | | |_RSL_SAPI_=_0_| |_| | | | | |_OML_SAPI_=_62_| |_| | | | | |_L2ML_SAPI_=_63_| |_| TRX |TEI 1 | | | | | |_| | | | |_| |_| |_| | |LAYER 2| | _ _ | | | _ |
34、| |_| | | | | |_|_RSL_SAPI_=_0_| |_| | | | | |_OML_SAPI_=_62_| |_| TRX |TEI 2 | | | |_L2ML_SAPI_=_63_| |_| | | | T E I | | | | |_| | | | |_RSL_SAPI_=_0_| | _ | | | |_OML_SAPI_=_62_| |_| | | | | |_L2ML_SAPI_=_63_| |_| | | | |_| | |_| TRX |TEI 3 | | | | | |_| | | |MANAGE-| | |_| |_| | |MENT | _ | _ _
35、| | | |_OML_SAPI_=_62_| |_| | | | | |_L2ML_SAPI_=_63_| |_| BCF |TEI 4 | | |_| |_| | | | | | _ _ | _ | | | | | | _ _ | OML _ _ _ _SAPI = 62_ | |_| |TEI 65 | | | | _ _ | L2ML_ _ _ _SAPI = 63_ | |_| | | |_|_| | |_| |_| | | |_| Figure 4.1: An example of Logical Layer 2 links supported by three permanent
36、 and one semipermanent links ETSI ETSI TS 148 056 V14.0.0 (2017-04)73GPP TS 48.056 version 14.0.0 Release 145 Functional contents The basic functional content of the layer 2 protocol is: - transparent layer 2 links and time fill; - point-to-point dedicated layer 2 links addressing both physical enti
37、ties and functional entities; - point-to-multipoint addressed links used for layer 2 management; - basic functions for TEI assignment and management; - basic priority functions; - basic supervision of links when not carrying traffic; - sequence control; - transmission error control; - control of err
38、ors not recoverable by retransmission. 6 LAPD functions The LAPD functions as specified in EN 300 125 are applicable. However, the exceptions and modifications specified in the remainder of the present document shall be used. 6.1 Exceptions and modifications In the following headlines from EN 300 12
39、5 are kept and references are made to the corresponding clause of EN 300 125. 6.1.1 Void 6.1.2 Command/Response field bit (C/R) (Refer to EN 300 125, part 2, clause 3.3.2) In GSM PLMNs BSC represents the network side and TRX/BCF the user side of the interface. 6.1.3 Service Access Point Identifier (
40、SAPI) (Refer to EN 300 125, part 2, clause 3.3.3) The SAPI values for the A-bis interface are as listed in table 6.1.3. ETSI ETSI TS 148 056 V14.0.0 (2017-04)83GPP TS 48.056 version 14.0.0 Release 14Table 6.1.3: Allocation of SAPI values and priority classes SAPI value Related layer 3 or layer manag
41、ement entity Priority 0 Radio signalling procedures 2 1 Reserved for packet mode communications using Q.931 call control procedures (Not used in GSM PLMN) - 16 Reserved for packet communication conforming to X.25 level 3 procedures (Not used in GSM PLMN - 62 Operation and maintenance procedure 1 63
42、Layer 2 management procedures 1 All others Reserved for future standardization - 6.1.4 TEI for point-to-point data link connection (Refer to EN 300 125, part 2, clause 3.3.4.2). The remaining Terminal Endpoint Identifier (TEI) values are used for the point-to-point data link connections associated w
43、ith the addressed Service Access Point (SAP). The range of TEI values shall be allocated as shown in table 6.1.4. Table 6.1.4: Allocation of TEI values TEI value User type 0-63 TEI assignment for fixed TRX and BCF addresses 64-126 TEI assignment for additional, TRX or BCF addresses NOTE: A BCF is gi
44、ven a separate layer 2 link only if it is not integrated with a TRX. 6.1.5 Commands and responses (Refer to EN 300 125, part 2, clause 3.6.1) The XID command and response are not used. 6.1.6 Exchange identification (XID) command/response (Refer to EN 300 125, part 2, clause 3.6.12) This functionalit
45、y is not used. 6.1.7 MDL-XID (Refer to EN 300 125, part 2, clause 4.1.1.9) This functionality is not used. 6.1.8 PH-DATA, PH DEACTIVATE and PH-ACTIVATE (Refer to EN 300 125, part 2, clauses 4.1.1.10 - 4.1.1.12) This functionality is not relevant. 6.1.9 MPH-ACTIVATE, MPH-DEACTIVATE an MPH-INFORMATION
46、 (Refer to EN 300 125, part 2, clauses 4.1.1.13 - 4.1.1.15) ETSI ETSI TS 148 056 V14.0.0 (2017-04)93GPP TS 48.056 version 14.0.0 Release 14This functionality is not relevant. 6.1.10 Priority indicator (Refer to EN 300 125, part 2, clause 4.1.3.1) The different SAPIs are given the priority classes as
47、 listed in table 1 when contending (with priority one as the highest). 6.1.11 Terminal Endpoint Identifier (TEI) management procedures (Refer to EN 300 125, part 2, clause 5.3) Due to the special assignment functions needed on the A-bis interface there are modifications and additions to the assignment procedures. The rest of clause 5.3 in EN 300 125, part 2, is kept if not stated otherwise. 6.1.11.1 General (Refer to EN 300 125, part 2, clause 5.3.1) TEI management for A-bis interface is based on the following procedural means: - a Subset of
