ETSI ETS 300 651 ed.1 (1996-09)

SLOVENSKI STANDARD
3SIST ETS 300 651:1999
01-jDQXDU-1999
'LJLWDOQHL]EROMãDQHEUH]YUYLþQHWHOHNRPXQLNDFLMH'(&73URILOSRGDWNRYQLK
VWRULWHY'63*HQHULþQDVWRULWHYSRGDWNRYQHSRYH]DYHVWRULWHYWLSD&UD]UHG
Digital Enhanced Cordless Telecommunications (DECT); Data Services Profile (DSP);
Generic data link service (service type C, class 2)
Ta slovenski standard je istoveten z: ETS 300 651 E1
ICS:
33.020 Telekomunikacije na splošno Telecommunications in
general
33.070.30 'LJLWDOQHL]EROMãDQH Digital Enhanced Cordless
EUH]YUYLþQHWHOHNRPXQLNDFLMH Telecommunications (DECT)
'(&7
3SIST ETS 300 651:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 651
TELECOMMUNICATION September 1996
STANDARD
Source: ETSI TC-RES Reference: DE/RES-03036
ICS: 30.020, 30.060.50
Key words: DECT, data, layer 2, mobility, profile, radio
Radio Equipment and Systems (RES);
Digital Enhanced Cordless Telecommunications (DECT);
Data Services Profile (DSP);
Generic data link service;
Service type C, class 2
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 92 94 42 00 - Fax: +33 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.
© European Telecommunications Standards Institute 1996. All rights reserved.

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ETS 300 651: September 1996
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
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 651: September 1996
Contents
Foreword .9
1 Scope .11
2 Normative references.11
3 Definitions and abbreviations .13
3.1 Definitions .13
3.2 Abbreviations .13
4 Description of services .15
4.1 Reference configuration.15
4.2 Service objectives.17
5 PHL requirements .17
6 MAC layer requirements.17
7 DLC layer requirements .17
7.1 C-plane requirements .17
7.2 U-plane requirements .17
8 NWK layer requirements.18
9 Management entity requirements.19
9.1 Link resource management .19
10 Generic interworking conventions and procedures .20
10.1 PAD functionality for character oriented user data .20
10.1.1 Character formatting .20
10.1.2 PAD operation .21
10.1.2.1 Transmission over DECT air interface .21
10.1.2.1.1 Data forwarding conditions .21
10.1.2.1.2 Transmission buffering and flow-
control .21
10.1.2.2 Reception over DECT air interface.21
10.1.2.2.1 Data reception.21
10.1.2.2.2 Receive buffering and flow control.21
10.2 PAD functionality for bit oriented user data.22
10.2.1 The character formatting.22
10.2.2 BPAD operation.22
10.2.2.1 Transmission over DECT air interface .22
10.2.2.1.1 Data forwarding conditions .22
10.2.2.1.2 Transmission buffering and flow-
control .23
10.2.2.2 Reception over DECT air interface.23
10.2.2.2.1 Data reception.23
10.2.2.2.2 Receive buffering and flow control.23
10.2.3 Selection of BPAD functionality.23
10.3 Control frame for V.24 interworking.23
10.4 Control frame for voice band modem interworking.25
10.5 Data-compression.25
10.6 In-call Service Change.26
10.6.1 Service Change Scope.26
10.6.2 <> Service Change .26
10.6.3 <> Service Change.26

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ETS 300 651: September 1996
Annex A (normative): Implementation of the LU3 service including LAP-U . 27
A.1 U-plane service characteristics. 27
A.1.1 General. 27
A.1.2 LAP-U type of operation .27
A.1.3 U-plane Link Identifier (ULI) .27
A.2 Data link service frame structure for LU3 . 28
A.2.1 General frame structure .28
A.2.2 LU2 frame delimiting and transparency . 28
A.2.3 Transmission order . 28
A.2.4 Invalid frames. 29
A.3 Elements of procedures and formats of fields for U-plane peer to peer communication . 29
A.3.1 General. 29
A.3.2 Address field formats . 29
A.3.3 Address field parameters . 29
A.3.3.1 Reserved bit (RES). 29
A.3.3.2 Command Response bit (C/R) . 29
A.3.3.3 SAPI field . 30
A.3.3.4 New Link Flag bit (NLF). 30
A.3.3.5 More data bit; M. 30
A.3.3.6 U-plane Link Identifiers. 31
A.3.4 Control field formats. 31
A.3.5 Checksum field parameters . 31
A.3.6 Commands and responses . 32
A.3.6.1 Information (I) command . 32
A.3.6.2 Receive Ready (RR) command/response . 32
A.3.6.3 Receive Not Ready (RNR) command/response. 33
A.3.6.4 REJect (REJ) command/response . 33
A.3.6.5 Set Asynchronous Balanced Mode (SABM) command . 33
A.3.6.6 Unnumbered Acknowledgement (UA) response . 33
A.4 Primitives for the LU3 service. 34
A.5 U-plane peer to peer procedures. 34
A.5.1 General. 34
A.5.2 Point to point acknowledged operation . 35
A.5.2.1 Procedure for the use of the P/F bit in LAP-U acknowledged information
transfer. 35
A.5.2.2 Establishing LAP-U multiple frame operation . 35
A.5.2.2.1 Overview . 35
A.5.2.2.2 LAP-U multiple frame establishment procedures . 35
A.5.2.3 Link maintenance and information transfer in LAP-U multiple frame
operation. 36
A.5.2.3.1 Transmitting I-frames. 37
A.5.2.3.2 Receiving I-frames . 37
A.5.2.3.2.1 P bit set to 1 . 37
A.5.2.3.2.2 P bit set to 0 . 37
A.5.2.3.3 Sending and receiving acknowledgements. 38
A.5.2.3.3.1 Sending acknowledgements . 38
A.5.2.3.3.2 Receiving acknowledgements. 38
A.5.2.3.4 Receiving REJ-frames . 38
A.5.2.3.5 Receiving RNR-frames . 39
A.5.2.3.6 LAP-U own receiver busy condition . 41
A.5.2.3.7 Waiting acknowledgement. 41
A.5.2.4 Release of LAP-U multiple frame operation . 42
A.5.2.5 Re-establishment of LAP-U multiframe operation . 42
A.5.2.5.1 Criteria for re-establishment. 42
A.5.2.5.2 Re-establishment procedure. 42
A.5.2.6 Exception handling . 43
A.5.2.6.1 General . 43
A.5.2.6.2 LAP-U exception condition reporting and recovery. 43

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ETS 300 651: September 1996
A.5.2.6.2.1 N(S) sequence error .43
A.5.2.6.2.2 N(R) sequence error.44
A.5.2.6.2.3 Timer recovery condition .44
A.6 Management procedures for LAP-U .44
A.6.1 LU3 establishment .44
A.6.2 LU3 release.44
Annex B (normative): LU3 parameters.45
B.1 LAP-U timer values .45
B.2 Constants .45
Annex C (normative): Specific interworking conventions .46
C.1 Scope of this annex.46
C.2 Interworking specific codings .47
C.2.1 IWU-Attribute coding.47
C.2.2 IWU attributes implemented .50
C.3 Interworking to V.24 circuits .51
C.3.1 Reference configuration.51
C.3.2 Global assumptions .51
C.3.3 Interworking procedures and conventions .52
C.3.3.1 Procedures at the DTE-side-IWF.52
C.3.3.1.1 DTE-Initiated link establishment.52
C.3.3.1.2 DCE-Initiated link establishment.52
C.3.3.1.3 DTE-Initiated link suspension .52
C.3.3.1.4 DCE-Initiated link suspension.52
C.3.3.1.5 DTE-Initiated link resume .52
C.3.3.1.6 DCE-Initiated link resume.52
C.3.3.1.7 DTE-Initiated link release .53
C.3.3.1.8 DCE-Initiated link release .53
C.3.3.2 Procedures at the DCE-side-IWF.53
C.3.3.2.1 DCE-Initiated link establishment.53
C.3.3.2.2 DTE-Initiated link establishment.53
C.3.3.2.3 DCE-Initiated link suspension.53
C.3.3.2.4 DTE-Initiated link suspension .53
C.3.3.2.5 DCE-Initiated link resume.54
C.3.3.2.6 DTE-Initiated link resume .54
C.3.3.2.7 DCE-Initiated link release .54
C.3.3.2.8 DTE-Initiated link release .54
C.3.3.3 PAD .54
C.3.3.4 Timing conventions .54
C.3.3.5 Interworking of modem status lines, BREAK condition and PAUSE
condition .54
C.3.3.5.1 BREAK condition .54
C.3.3.5.2 PAUSE condition .55
C.3.3.6 Interworking of flow control.55
C.3.3.6.1 Flow control across the DTE/DTE-side-IWF interface .55
C.3.3.6.2 Flow control across the DCE-side-IWF/DCE interface.55
C.4 Interworking to connection-oriented bearer services .56
C.4.1 Scope.56
C.4.2 Reference configuration.56
C.4.2.1 PP TAF.57
C.4.2.2 FP IWF .57
C.4.2.3 General Configuration .58
C.4.3 PP Procedures.58
C.4.3.1 C-plane procedures.58
C.4.3.1.1 Suspend and resume procedures .58

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ETS 300 651: September 1996
C.4.4 FP procedures. 59
C.4.4.1 C-plane . 59
C.4.4.1.1 Suspend and resume procedures. 59
C.4.5 Network modem interworking service using V.24 connection. 59
C.4.5.1 General . 59
C.4.5.2 Reference configuration. 60
C.4.5.3 TAF Interworking to V.24/V25bis. 60
C.4.5.3.1 General . 60
C.4.5.3.2 V.24 interchange circuit handling rules . 60
C.4.5.3.3 Call establishment signalling handling . 61
C.4.5.3.4 V.25bis interworking to DECT CC primitives . 61
C.4.5.3.4.1 PP originated calls. 62
C.4.5.3.4.1.1 Call establishment. 62
C.4.5.3.4.1.2 Call release . 62
C.4.5.3.4.2 PP terminated calls . 62
C.4.5.3.4.2.1 Call establishment. 62
C.4.5.3.4.2.2 Call release . 63
C.4.5.3.5 Flow control. 63
C.4.5.3.6 Break signalling procedures. 63
C.4.5.3.7 PAUSE condition. 63
C.4.5.3.8 Data coding selection. 64
C.4.5.3.9 Data transmission . 64
C.4.5.4 DECT FP Interworking procedures. 64
C.4.5.4.1 General . 64
C.4.5.4.2 Call establishment signalling handling . 64
C.4.5.4.3 V.24 Interchange circuit handling rules. 65
C.4.5.4.4 Flow control. 65
C.4.5.4.5 Break signalling procedures. 65
C.4.5.4.6 PAUSE condition. 66
C.4.5.4.7 Modem selection. 66
C.4.5.4.8 Data coding selection. 66
C.4.5.4.9 Data transmission . 67
Annex D (normative): Service C2: Fixed radio Termination (FT) DLC PICS proforma . 69
D.1 Standardized symbols for the status column. 69
D.2 Capabilities . 70
D.2.1 Major capabilities. 70
D.2.1.1 C-plane capabilities . 70
D.2.1.1.1 C-plane services . 70
D.2.1.1.2 C-plane procedures . 70
D.2.1.1.2.1 Point-to-point acknowledged operation 70
D.2.1.1.2.1.1 Class A procedures. 70
D.2.1.1.2.1.2 Class B procedures. 71
D.2.1.1.2.2 Unacknowledged operation. 71
D.2.1.1.2.3 Broadcast operation . 72
D.2.1.2 U-plane capabilities . 72
D.2.1.2.1 U-plane services . 72
D.2.1.2.2 U-plane procedures . 72
D.2.1.2.2.1 LU2 Frame relay services . 72
D.2.1.3 Management procedures. 74
D.2.2 PDUs. 75
D.2.2.1 C-plane PDUs. 75
D.2.2.1.1 C-plane frame structure . 75
D.2.2.1.2 C-plane messages. 75
D.2.2.2 U-plane PDUs. 84
D.2.2.2.1 U-plane frame types. 84
D.5.2.2.2 U-plane frame structures . 85
D.2.2.2.3 U-plane frame elements. 86
D.2.3 Timers . 88
D.2.3.1 C-plane timers . 88
D.2.3.2 U-plane timers . 88

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ETS 300 651: September 1996
D.2.4 Protocol error handling.88
D.2.4.1 C-plane protocol error handling.88
D.2.4.2 U-plane protocol error handling.89
Annex E (normative): Service C2: Portable radio Termination (PT) DLC PICS proforma .90
E.1 Standardized symbols for the status column .90
E.2 Capabilities.91
E.2.1 Major capabilities .91
E.2.1.1 C-plane capabilities .91
E.2.1.1.1 C-plane services.91
E.2.1.1.2 C-plane procedures .91
E.2.1.1.2.1 Point to point acknowledged operation.91
E.2.1.1.2.1.1 Class A procedures .91
E.2.1.1.2.1.2 Class B procedures .92
E.2.1.1.2.2 Unacknowledged operation .92
E.2.1.1.2.3 Broadcast operation.93
E.2.1.2 U-plane capabilities .93
E.2.1.2.1 U-plane services.93
E.2.1.2.2 U-plane procedures .93
E.2.1.2.2.1 LU2 Frame relay services.93
E.2.1.3 Management procedures .95
E.2.2 PDUs.96
E.2.2.1 C-plane PDUs .96
E.2.2.1.1 C-plane frame structure.96
E.2.2.1.2 C-plane messages.97
E.2.2.2 U-plane PDUs .106
E.2.2.2.1 U-plane frame types .106
E.5.2.2.2 U-plane frame structures.107
E.2.2.2.3 U-plane frame elements .108
E.2.3 Timers.109
E.2.3.1 C-plane timers.109
E.2.3.2 U-plane timers.109
E.2.4 Protocol error handling.109
E.2.4.1 C-plane protocol error handling.109
E.2.4.2 U-plane protocol error handling.110
Annex F (normative): Service C2: Fixed radio Termination (FT) NWK PICS proforma.111
F.1 Standardized symbols for the status column .111
F.2 Capabilities.113
F.2.1 Major capabilities .113
F.2.1.1 Services.113
F.2.1.2 Procedures.113
F.2.2 Protocol parameters .115
F.2.2.1 Timer support .115
F.2.2.2 System wide parameters.116
F.2.2.3 Other parameters .116
F.2.3 Messages.117
F.2.3.1 CC messages.117
F.2.3.2 Mobility management messages.122
F.2.3.3 Link control entity messages.133
F.2.4 Information elements .135
F.2.4.1 Fixed length information element support .136
F.2.4.2 Variable length information element support.137
F.2.4.3 B-Format message structure support .147
F.2.5 Protocol error handling.149
F.2.6 Negotiation capabilities .150
F.2.7 Multi-layer dependencies .150
Annex G (normative): Service C2: Portable radio Termination (PT) NWK PICS proforma.151

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G.1 Standardized symbols for the status column. 151
G.2 Capabilities . 153
G.2.1 Major capabilities. 153
G.2.1.1 Services . 153
G.2.1.2 Procedures . 153
G.2.2 Protocol parameters. 156
G.2.2.1 Timer support . 156
G.2.2.2 System wide parameters . 157
G.2.2.3 Other parameters . 157
G.2.3 Messages. 157
G.2.3.1 CC messages . 157
G.2.3.2 Mobility management messages . 162
G.2.3.3 Link control entity messages . 173
G.2.4 Information elements. 175
G.2.4.1 Fixed length information element support . 176
G.2.4.2 Variable length information element support . 177
G.2.4.3 B-Format message structure support. 187
G.2.5 Protocol error handling. 189
G.2.6 Negotiation capabilities . 190
G.2.7 Multi-layer dependencies . 190
Annex H (normative): Service C2: Fixed radio Termination (FT): provisions from ETS 300 175-5
(2nd edition) specifically required by this profile . 191
Annex I (normative): Service C2: Portable radio Termination (PT): provisions from ETS 300 175-5
(2nd edition) specifically required by this profile . 201
History. 211

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ETS 300 651: September 1996
Foreword
This European Telecommunication Standard (ETS) has been produced by the Radio Equipment and
Systems (RES) Technical Committee of the European Telecommunications Standards Institute (ETSI).
Transposition dates
Date of adoption of this ETS: 23 August 1996
Date of latest announcement of this ETS (doa): 31 December 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 June 1997
Date of withdrawal of any conflicting National Standard (dow): 30 June 1997

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ETS 300 651: September 1996
1 Scope
This European Telecommunication Standard (ETS) defines a profile for Digital Enhanced Cordless
Telecommunications (DECT) systems conforming to ETS 300 175, Parts 1 to 9 [1] to [9]. It is part of a
family of profiles which build upon and extend each other, aimed at the general connection of terminals
supporting non-voice services to a fixed infra-structure, private and public.
This ETS specifies a Link Access Protocol (LAP) service suitable for non-transparent transfer of
character-oriented or bit-oriented data streams and intended for use in private and public roaming
applications. It builds upon the generic frame relay service offered by the Data Services Profile (DSP)
base standard (Type A and Type B services) and adds full Data Link Control (DLC) functionality to the
basic service. Annexes to this ETS contain interworking conventions to specific character orientated
services.
This ETS defines the Type C Service, Mobility Class 2. The Type C service is fully compatible with both
the Type A and Type B services defined in ETS 300 435 [11].
This ETS defines the additional requirements on the Physical Layer (PHL), Medium Access Control (MAC)
layer, DLC layer and Network (NWK) layer of DECT. The standard also specifies Management Entity (ME)
requirements and generic Interworking Conventions (IC) which ensure the efficient use of the DECT
spectrum.
2 Normative references
This ETS incorporates, by dated or 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 of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ETS 300 175-1 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 1:
Overview".
[2] ETS 300 175-2 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 2: Physical
layer".
[3] ETS 300 175-3 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 3: Medium
Access Control (MAC) layer".
[4] ETS 300 175-4 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 4: Data
Link Control (DLC) layer".
[5] ETS 300 175-5 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 5: Network
(NWK) layer".
[6] ETS 300 175-6 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 6:
Identities and addressing".
[7] ETS 300 175-7 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 7: Security
features".
[8] ETS 300 175-8 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 8: Speech
coding and transmission".
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ETS 300 651: September 1996
[9] ETS 300 175-9 (1996): "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Common Interface (CI); Part 9: Public
Access Profile (PAP)".
[10] ETS 300 444: "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Generic Access Profile (GAP)".
[11] ETS 300 435: "Radio Equipment and Systems (RES); Digital European
Cordless Telecommunications (DECT); Data Services Profile (DSP); Base
standard including inter-Working to connectionless networks (service types A
and B, Class 1)".
[12] CCITT Recommendation Q.921 (1988): "Digital subscriber signalling system no.
1 data link layer".
[13] CCITT Recommendation V.42: "Error-correcting procedures for DCEs using
asynchronous-to-synchronous conversion".
[14] CCITT Recommendation V.24 (1988): "List of definitions for interchange circuits
between data terminal equipment (DTE) and data circuit-terminating equipment
(DCE)".
[15] CCITT Recommendation V.25bis (1988): "Automatic calling and/or answering
equipment on the general switched telephone network (GSTN) using the
100-series interchange circuits".
[16] CCITT Recommendation V.42bis (1990): "Data compression procedures for
data circuit- terminating equipment (DCE) using error correcting procedures".
[17] ETR 043: "Radio Equipment and Systems (RES); Digital European Cordless
Telecommunications (DECT); Common interface; Services and facilities
requirements specification".
[18] ETS 300 476-2: "Radio Equipment and Systems (RES); Digital Enhanced
Cordless Telecommunications (DECT); Common Interface (CI); Protocol
Implementation Conformance Statement (PICS) proforma; Part 2: Data Link
Control (DLC) layer - Portable radio Termination (PT)".
[19] ETS 300 476-3: "Radio Equipment and Systems (RES); Digital Enhanced
Cordless Telecommunications (DECT); Common Interface (CI); Protocol
Implementation Conformance Statement (PICS) proforma; Part 3: Medium
Access Control (MAC) layer - Portable radio Termination (PT)".
[20] ETS 300 476-4: "Radio Equipment and Systems (RES); Digital Enhanced
Cordless Telecommunications (DECT); Common Interface (CI); Protocol
Implementation Conformance Statement (PICS) proforma; Part 4: Network
(NWK) layer - Fixed radio Termination (FT)".

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ETS 300 651: September 1996
3 Definitions and abbreviations
3.1 Definitions
For the purpose of this ETS, the following definitions apply:
mobility class 1: Local area applications, for which terminals are pre-registered off-air with one or more
specific Fixed Parts (FPs), and establishment of service and user parameters is therefore implicit,
according to a profile-defined list.
mobility class 2: Private and public roaming applications for which terminals may move between FPs
within a given domain and for which association of service parameters is explicit at the time of service
request.
multiframe: A repeating sequence of 16 successive Time Division Multiple Access (TDMA) frames, that
allows low rate or sporadic information to be multiplexed (e.g. basic system information or paging).
service type A: Low speed frame relay, with a net sustainable throughput of up to 24 kbits/s, optimized
for bursty data, low power consumption and low complexity applications such as hand-portable
equipment.
service type B: High performance frame relay, with a net sustainable throughput of up to 552 kbits/s,
optimized for high speed and low latency with bursty data. Equipment implementation the Type B profile
inter-operates with Type A equipment.
service type C: Non-transparent connection of data streams requiring Link Access Protocol (LAP)
services, optimized for high reliability and low additional complexity. This builds upon the services offered
by the type A or B profiles.
TDMA frame: A time-division multiplex of 10 ms duration, containing 24 successive full slots. A TDMA
frame starts with the first bit period of full slot 0 and ends with the last bit period of full slot 23.
3.2 Abbreviations
For the purpose of this ETS, the following abbreviations apply:
ACK Acknowledgement
AMCI Advanced MAC Connection Identifier
BPAD Bit oriented Packet Assembler/Disassembler
C higher layer control Channel (see CS and CF)
CC Call Control. A NWK layer functional grouping
CF higher layer signalling Channel (Fast)
CISS Call Independent Supplementary Services
CLMS Connectionless Message Services
COMS Connection Oriented Message Services
C-plane Control plane
CS higher layer signalling Channel (Slow)
DCE Data Circuit terminating Equipment
DECT Digital Enhanced Cordless Telecommunications
DLC Data Link Control
DTE Data Terminal Equipment
FP Fixed Part
FT Fixed radio Termination
GAP Generic Access Profile
GSM Global System for Mobile communication
I higher layer Information channel (see IP)
IP higher layer Information channel (Protected)
IPUI International Portable User Identity
ISDN Integrated Services Digital Network
IWF Interworking Functions
IWU Interworking Unit
LAP-B Link Access Procedure (Balanced)

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ETS 300 651: September 1996
LAP-C Link Access Procedure (Control)
LAP-D Link Access Procedure (ISDN D-channel)
LAP-U Link Access Procedure (U-plane)
LCE Link Control Entity
LLME Lower Layer Management Entity
LLN Logical Link Number (DLC layer)
MAC Medium Access Control
MCI MAC Connection Identifier
MM Mobility Management
NLF
...