1、ETSI/TC SMG Released by : ETSI/PT 12 Release date: February 1992 RELEASE NOTE Recommendation GSM 04.06 MS - BSS Data Link Layer Specification Previously distributed version : 3.9.0 (Updated Release 1/90) New Released version February 92 : 3.9.0 (Release 92, Phase 1) w No changes since the previously
2、 distributed version. 3Lt04583 0070554 7b8 ELECOMMUNICATION STANDARD 2nd FINAL DRAFT prl-ETS 300 021 . February 1992 Source: ETSI TC-SMG Reference: GSM 04.06 UDC: 621.396.21 Key words: European Digital Cellular Telecommunications System, Global System for Mobile Communications (GSM) European digital
3、 cellular telecommunications system (phase I ); Mobile Station - Base Station System (MS-BSS) interface data link layer specification ETSI European Telecommunications Standards Institute ETSI Secretariat: B.P.152 . F - 06561 Valbonne Cedex . France TP. + 33 92 94 42 O0 TF. + 33 93 65 47 16 Tx. 47 O0
4、 40 F 0 European Telecommunications Standards Institute 1 992. All rights reserved. Previous page is blank No part may be reproduced or used except as authorised by contract or other written permission. The copyright and the foregoing restriction on reproduction and use extend to all media in which
5、the information may be embodied. 2nd Final draft prl-ETS 300 021:1992 3404583 0070555 bT4 * Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “E
6、TSI Standards Management Dept.“ at the address shown on the title page. 3404583 007055b 530 2nd Final draft prl-ETS 300 021 :1992 Fore word This second Final draft Interim European Telecommunication Standard (I-ETS) has been produced by the Special Mobile Group (SMG), a Technical Committee of the Eu
7、ropean Telecommunications Standards Institute (ETSI). The final drafts dealing with the GSM system were adopted by vote in May 1991 but were not published. This was because amendments, agreed by ETSI TC-SMG at subsequent meetings, were made to some of the drafts. However, other drafts have not been
8、amended since the first vote. This updated draft is now considered to be stable enough for submission to second vote. This draft LETS describes the data link layer signalling protocol at the Mobile Station - Base Station (MS-BS) interface within the European digital cellular telecommunications syste
9、m (phase 1 1, Reference is made within this I-ETS to the following technical specifications (NOTE 1): GSM 04.03 Mobile Station - Base Station System (MS-BSS) interface: Channel structures and access capabilities. GSM 04.05 Mobile Station - Base Station System (MS-BSSI data link layer - general aspec
10、ts. GSM 04.07 Mobile radio interface signalling layer 3 - general aspects. GSM 04.08 Mobile radio interface - layer 3 specification. The above specifications, together with Annexes A and G of this standard, are normative. NOTE 1: ETSI has constituted stable and consistent documents which give techni
11、cal specifications for the implementation of the European digital cellular telecommunications system. Historically, these documents have been identified as “GSM recommendations“. Some of these recommendations may subsequently become Interim European Telecommunication Standards (I-ETSs) or European T
12、elecommunication Standards (ETSs), whilst the others will be renamed ETSI-GSM Technical Specifications. These ETSI-GSM Technical Specifications are, for editorial reasons, still referred to as GSM recommendations in some current GSM documents. The numbering and version control system used for ETSI-G
13、SM Technical specifications is the same as that used for GSM recommendations. NOTE 2: Items in this draft indicated as not complete, or requiring further study or work, are not required for the Phase 1 implementation of the European digital cellular telecommunications system. ETSi/GSM 34045153 00705
14、57 477 version 3.9.0 Recommendation GSM 04.06 Title: MS-BSS INTERFACE DATA LINK LAYER SPECIFICATION List of contents : see next pages Date : February 1992 Original language: English Number of pages: 82 . H 3404583 0070558 303 GSM 04.06 - v. 3.9.0 - Page 2 List of contents: O Scope 1 General 2 Frame
15、structure for peer-to-peer communication 2.1 General 2.2 Frame delimitation and fill bits 2.3 Address field 2.4 Control field 2.5 Length indicator field 2.6 Information field 2.7 Transparency 2.8 Format convention 3 Elements of procedure and formats of fields for data link layer peer-to-peer communi
16、cation 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 General Address field format Address field variables Control field formats Control field parameters and associated state variables Length indicator field format Length indicator field variables Commands and responses 4 Elements for layer- to-layer communication
17、 4.1 4.2 Primitive procedures Definition of primitives and parameters = 3YOY583 0070559 ZYT GSM 04.06 - v. 3.9.0 - Page 3 5 Definition of the peer-to-peer procedures of the data link layer 5.1 5.2 5.3 5.4 5.5 5.6 5-7 5.8 Genera Procedure for the use of the P/F bit Procedures for unacknowledged infor
18、mation transfer Procedure for establishment and release of multiple frame operation Procedures for information transfer in multiple frame operation Abnormal release and reestablishment of multiple frame operation Exception condition reporting and recovery for multiple frame operation List of system
19、parameters for multiple frame operation 6 Specialities of protocol Annex A Random access procedure . ANNEX G Handling of frames with parameter errors I 3404583 0070560 TbL W GSM 04.06 - v. 3.9.0 - Page 4 O SCOPE 1 The scope of this Recommendation is to define the data link layer protocol to be used
20、for signalling, and possibly also for other applications, on the MS-ES interface. Mandatory requirement For SAPI=O (i.e. signalling) or 3, the protocol shall use window size 1 and the peer entities are not allowed to enter the receiver busy state. GENERAL This Recommendation specifies the frame stru
21、cture, elements of procedure, format of fields and procedures for the proper operation of the Link Access Procedure on the Dm channel, LAPDm. When the mention for “further study“ or “FS“ or “FFS“ is present throughout this document this means this is not relevant for EISI-GSM phase 1 standard. Note:
22、 The term Dm channel is used for convenience to designate the collection of ail the various signalling channels required in the GSM system. See also Recommendation GSM 04.03. The concepts, terminology, overview description of LAPDm functions and procedures, and the relationship with other Recommenda
23、tions are described in general terms in Recommendation GSM 04.05. The frame formats defined for LAPDm are based on those defined for LAPD. However, there are important differences between LAPDm and LUD, in particular with regard to frame delimitation methods and transparency mechanisms. These differ
24、ences are necessary for operation within the constraints set by the radio path. WDm supports two modes of operation: - unacknowledged operation using U1 frames - acknowledged operation using the multiple frame procedure 3404583 0070563 9T8 GSM 04.06 - v. 3.9.0 - Page 5 As a choice of implementation,
25、 the two modes of operation may be implemented independently of each other. This is possible since there . is no interactions between the two modes, other than queuing at the transmitter, even when they coexist on the same physical channel. For BCCHs and CCCHs only the unacknowledged mode of operati
26、on needs to be implemented. LAPDm is used for information sent on the control channels BCCH, ASCH, , PCH, FACCH, SACCH and SDCCH as defined in Recommendation GSM 04.03. Note: AGCH and PCH are sometimes referred to by the collective name CCCH and FACCH, SACCH and SDCCH are, similarly, referred to by
27、the collective name DCCH. LAPDm may also be used on other types of channel. Note: As stated in Recommendation GSM 04.05, the term “data link layer“ is used in the main text of this Recommendation. However, mainly in figures and tables, the terms “layer 2“ and “L2“ are used as abbreviations. Furtherm
28、ore , in accordance with Recommendations GSM 04.07 and GSM 04.08, the term “layer 3“ is used to indicate the layer above the data link layer. The Recommendation is organised as follows : The specification for the random access channel is contained in Annex A even though this is not a LAPDm function.
29、 This part of the Recommendation is descriptive and does not constrain the implementation of the random access function. The procedure is used on the RACH. The frame structure for peer-to-peer communication is given in sect. 2 . The elements of procedure and formats of fields are given in sect. 3. T
30、he elements of layer-to-layer communication are contained in sect. 4. The details of the peer-to-peer procedures are given in sect 5. Annex G gives an overview of actions taken on frames containing parame ter errors. 3404583 O070562 834 GSM 04.06 - v. 3.9.0 - Page 6 2 2.1 FRAME STRUCTURE FOR PEER-TO
31、-PEER COMMUNICATION General All data link layer peer-to-peer exchanges are in frames conforming to one of the formats shown in Figure 1. Several format types are shown in the Figure: Format A is used on DCCHs for frames where there is no information field, Format B is used on DCCHs for frames contai
32、ning an information field, and formats Abis and Bbis are equivalent to formats A and B but are used on channels only supporting unacknowledged mode of operation and SAPI=O (BCCH, PCH, AGCH). The format Abis may be used when there is no information to be sent on the channel. In addition there is a Fo
33、rmat C for transmission of random access signals. Format C frames are described in Annex A. Format A/Abis and B/Bbis frames are described in the remainder of this Recommendation. = 3q04583 00705b3 770 GSM 04.06 - v. 3.9.0 - Page 7 bit 8 7 6 5 4 3 2 1 I Octet no bit 8 7 6.5 4 3 2 1 1 k k+l k+2 n n+ 1
34、 N201+n k k+ 1 k+2 n n+l N N+ 1 N201+n Figure 1/GSM 04.06 (sheet 1 of 2) General frame formats = 3404583 0070564 607 GSM 04.06 - v. 3.9.0 - Page 8 bit 8 7 6 5 4 3 2 1 I 1 Octet no Length indicator field I I N201+m Format type Abis I I m+ Fill bits Format type Bbis Figure 1/GSM 04.06 (Sheet 2 of 2) G
35、eneral frame formats = 34U4583 0070565 543 GSM 04.06 - v. 3.9.0 - Page 9 The parameter N201 takes a fixed value for each type of channel, see section 5.8.3, and determines the maximum nimber of octets in the information field of a frame. 2.2 Frame delimitation and fill bits Frame delimitation is pro
36、vided by the physical layer: - in format type A and B frames at the beginning of the frame for determining the start of the first octet in the address field and in format type Abis and Bbis frames for determining the start of the first octet for the length indicator field: - at the end of the frame
37、for determining the last bit of the frame. The end of the useful part of the frame, i e the end of the length indicator field in type A/Abis frames and the end of the information field in type B/Bbis frames, is determined by a length indicator contained in the length indicator field. - If the length
38、 indicator has a vaue less than N201, the frame contains fill bits. Octets containing fill bits shall take the binary value “00101011“ (See notes 1 and 2). Note 1: This value is chosen due to the modulation and interleaving scheme used in the GSM system. Note 2: Mobile Stations may use the binary va
39、lue “11111111“. 2.3 Address field The address field may consist of a variable number of octets. However, for applications on control channels the field consists of only one octet. The address field identifies the SAP for which a command frame is intended and the SAP transmitting a response frame. Th
40、e format of the address field is defined in section 3.2. 2.4 Control field “he control field consists of one octet. The format of the control field is defined in section 3.4. 3404583 00705bb 48T GSM 04.06 - v. 3.9.0 - Page 10 2.5 Length indicator field The length indicator field may consist of a var
41、iable number of octets. However, for applications on control channels the field consists of only one octet. The format of the field is defined in section 3.6. 2.6 Information field The informatic; field of a frame, when present, follows the length indicator field (see 2.5 above). The maximum number
42、of octets in the information field (N201) is defined in section 5.8.3. 2.7 Transparency Because of the frame delimitation technique used (see section 2.2). the frame can include any possible sequence of bits without the need for additional transparency mechanisms. 2.8 Format convention 2.8.1 Numberi
43、ng convention “he basic convention used in this Recommendation is illustrated in Figure 2. The bits are grouped into octets. The bits of an octet are shown horizontally and are numbered from 1 to 8.,Multiple octets are shown vertically and are numbered from 1 to n. bit 8 7 6 5-4 3 2 1 I I Octet no I
44、 I ln Figure 2/GSM 04.06 Format convention. = 340t4583 00705b7 3Lb = 4 3 2 12 2 2 GSM 04.06 - v. 3.9.0 - Page 11 1st octet of field 2.8.2 Order of bit transmission The order of bit transmission is defined in Rec. GSM 04.04. 2.8.3 Field mapping convention When a field is contained within a single oct
45、et, the lowest bit number of the field represents the lowest order value. , When a field spans more than one octet, the order of bit values within each octet progressively decreases as the octet number increases. In that part of the field contained in a given octet the lowest bit number represents t
46、he lowest order value. For example, a bit number can be identified as a couple (o, b) where o is the octet number and b is the relative bit number within the.octet. Figure 3 illustrates a field that spans from bit (1, 3) to bit (2, 7). The high order bit of the field is mapped on bit (1, 3) and the
47、low order bit is mapped on bit (2, 7). bit 8 7 6 5 4 3.2 1 I 2nd octet of field 121 201 Figure 3/SM 04 .O6 Field mapping convention. 3404583 0070568 252 W Spare LPD SAPI C/R FA= 1 L 3 3.1 3.2 GSM 04.06 - v. 3.9.0 - Page 12 ELEMENTS OF PROCEDURES AND FORMATS OF FIELDS FOR DATA LINK LAYER PEER- TO-PEE
48、R COMMUNICATION General The elements of procedures define the commands and responses that are used on the data link connections carried on the Dm channel. Procedures are derived from these elements of procedures and are described in section 5. Address field format The 5. The format of the address fi
49、eld for control channels is shown in Figure address field extension bit, EA, enables extension of the field to span more than one octet. The Link Protocol Discriminator (LPD) shall take the following value (Note) : O O corresponds to the use in this Recommendation, The field consists of the address field extension bit, EA, the command/response bit, C/R, and the SAPI. Note: O 1 corresponds to the use for SMSCB (see Rec. GSM 04.12). 3404583 0070567 177 GSM 04.06 - v. 3.9.0 - Page i3 3.3 Address field variables 3.3.1 Address field extension bit (FA) The address field range is exten
