TS 27.010
Terminal Equipment to User Equipment (TE-UE)
Multiplexer Protocol
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2024/03 … p.
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2022/03 54 p.
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2002/03 54 p.
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- Rapporteur:
- Mrs. Biondic, Nevenka
Ericsson LM
full Table of Contents for TS 27.010 Word version: 17.0.0
0 Introduction
1 Scope
2 References
3 Abbreviations
4 Overview of Multiplexing System
5 Non Error Recovery mode Options
5.1 Service Interface Definition
5.2 Frame Structure
5.3 Frame Types
5.4 Procedures and States
5.5 Convergence Layers
5.6 DLCI Values
5.7 System Parameters
5.8 Start-up and close-down of multiplexer
6 Error Recovery Mode Option
6.1 Frame Types
6.2 Procedure and State
A Advice to TE software implementers
B Explanatory notes on the CRC Calculation
$ Change History
0 Introduction p. 6
The multiplexer protocol described in the present document operates between an UE and a TE and allows a number of simultaneous sessions over a normal serial asynchronous interface. Each session consists of a stream of bytes transferring various kinds of data; for instance, voice, fax, data, SMS, CBS, phonebook maintenance, battery status, GPRS, USSD etc. This permits, for example, SMS and CBS to be transferred to a TE when a data connection is in progress. Many other combinations are possible including digital voice. It is, for instance, possible to transfer digital voice in combination with SMS. The multiplexer allows a complete system to be partitioned in a flexible way between a UE and TE.
The design of the multiplexer is flexible and independent of UE/TE platforms, and allows existing applications to work without any modifications.
The multiplexer is designed, with special care for battery-powered devices, to include very important functionality such as power saving control and priorities. It is also specially designed to require minimum processing power and memory consumption.
The multiplexer is defined as a single mode with different options based on the ISO HDLC standard (ISO/IEC 13239) although the basic option is not in accordance with HDLC.
In the basic option, the multiplexer does not make use of any transparency mechanism or error recovery method. The advanced option uses the ISO HDLC standard transparency mechanism and gives the multiplexer an easy re-synchronisation method and the ability to operate over links which use DC1/DC3 (XON/XOFF) flow control. The advanced option also may include error-recovery for links subject to errors.
In its basic option, the multiplexer is intended for use in situations where the link between UE and TE is of a very good quality and where the HDLC transparency mechanism (byte stuffing) can not be implemented in the UE. If an UE supports the HDLC transparency mechanism, it shall be used by the multiplexer. The ISO HDLC transparency mechanism must be used if loss of synchronisation may occur caused by, for example, data over-runs or under-runs. The error-recovery option should be used in situations where the link is subject to errors.
The multiplexer is based on a control channel. On this channel, management information is exchanged, such as parameter negotiation, power saving control information, testing, flow control, close down etc.
The multiplexer is optional, but when supported, it is activated with the AT+CMUX command described in TS 27.007.
1 Scope p. 7
The scope of the present document is to define a multiplexing protocol between a UE and a TE. The multiplexing protocol can be used to send any data, for instance voice, SMS, USSD, fax etc.
The present document describes the protocol, but not the commands or data transported with it.
2 References p. 7
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] Void.
[2]
ISO/IEC 13239 (1997): "Information technology - Telecommunications and information exchange between systems - High-level data link control (HDLC) procedures".
[3]
TS 27.005: "Use of Data Terminal Equipment - Data Circuit terminating Equipment (DTE - DCE) interface for Short Message Service (SMS) and Cell Broadcast Service (CBS)".
[4]
TS 27.007: "AT command set for User Equipment (UE)".
[5]
TR 21.905: "Vocabulary for 3GPP Specifications".
[6]
TS 46.021: "Half rate speech; Substitution and muting of lost frames for half rate speech traffic channels".
[7]
ISO/IEC 646 (1991): "Information technology - ISO 7-bit coded character set for information interchange".
3 Abbreviations p. 7
For the purposes of the present document, the following abbreviations apply:
ABM
Asynchronous Balanced Mode
DLC
Data Link Connection
DM
Disconnected Mode
ERM
Error-Recovery Mode
FCS
Frame Check Sequence
MSC
Modem Status Command
PSC
Power Saving Control
SABM
Set Asynchronous Balanced Mode
UAU
Unumbered Acknowledgement
UIH
Unnumbered Information with header Check
UI
Unnumbered Information
Additional abbreviations can be found in TR 21.905.
4 Overview of Multiplexing System p. 8
The multiplexer provides mechanisms for conveying streams of data between TE and UE over a single start-stop framed, serial link. Figure 1 shows the arrangement of the various protocol levels and functions. The multiplexer layer provides multiplexing of data arranged in octet streams with no other framing; if the structure of the data has to be conveyed, a convergence layer may be necessary. The present document defines some convergence layers, others may be added later.
The multiplexer provides a virtual connection between a process in the TE and a similar process in the UE. For example, a PC application supporting SMS functions could be connected to the SMS handler in the UE via a multiplexer channel.
The present document uses start-stop transmission with eight-bit characters. Communication between the two multiplexing entities takes place using frames constructed as defined below.
Each channel between TE and UE is called a Data Link Connection (DLC) and is established separately and sequentially.
Each DLC may have individual flow control procedures for buffer management purposes and the aggregate link also has overall flow control mechanisms.
DLCs have two modes of operation; Error-Recovery Mode (ERM) and non-error-recovery mode (non-ERM), the choice of mode is made when a DLC is established. DLCs using error recovery mode may exist on the same link as DLCs using non-error recovery mode. If the error-recovery mode (ERM) is to be used at least on one DLC, then the multiplexer must be configured with the ISO HDLC transparency mechanism. The use of error recovery mode is optional. Non-error recovery mode uses the UI frame or UIH frame to carry user data; error recovery mode uses the I frame.
The multiplexer has three operating options, basic, advanced without error recovery and advanced with error recovery. The characteristics of the options are:
Basic:
- length indicator used instead of the HDLC transparency mechanism;
- different flag octet from that used by HDLC;
- can not be used on links which use XON/XOFF flow control;
- may have longer recovery procedure from loss of synchronisation.
- asynchronous HDLC procedures in accordance with ISO/IEC 13239;
- can be used on links which use XON/XOFF flow control;
- recovers quickly from loss of synchronisation.
- Uses HDLC error-recovery procedures.
5 Non Error Recovery mode Options p. 9
5.1 Service Interface Definition p. 9
5.1.1 Service Definition Model p. 9
5.1.2 Start up services p. 10
5.1.3 DLC establishment services p. 11
5.1.4 Data services p. 12
5.1.5 Power Control services p. 12
5.1.5.1 Sleep services p. 12
5.1.5.2 Wakeup services p. 12
5.1.6 DLC Release services p. 12
5.1.7 Close down services p. 13
5.1.8 Control Services p. 13
5.2 Frame Structure p. 16
5.2.1 Frame Fields p. 16
5.2.1.1 Flag Sequence Field p. 16
5.2.1.2 Address Field p. 16
5.2.1.3 Control Field p. 17
5.2.1.4 Information Field p. 17
5.2.1.5 Length Indicator p. 17
5.2.1.6 Frame Checking Sequence Field (FCS) p. 18
5.2.2 Format Conventions p. 18
5.2.3 Frame Validity p. 19
5.2.4 Frame Abort p. 19
5.2.5 Inter-frame Fill p. 19
5.2.6 Basic Option p. 19
5.2.6.1 Constraint p. 19
5.2.7 Advanced Option p. 20
5.3 Frame Types p. 21
5.3.1 Set Asynchronous Balanced Mode (SABM) command p. 21
5.3.2 Unnumbered Acknowledgement (UA) response p. 21
5.3.3 Disconnected Mode (DM) response p. 21
5.3.4 Disconnect (DISC) command p. 21
5.3.5 Unnumbered information with header check (UIH) command and response p. 21
5.3.6 Unnumbered Information (UI) command and response p. 22
5.4 Procedures and States p. 22
5.4.1 DLC Establishment p. 22
5.4.2 DLC Release p. 22
5.4.3 Information Transfer p. 22
5.4.3.1 Information Data p. 22
5.4.3.2 Priority p. 23
5.4.4 Frame Variables p. 23
5.4.5 Time-out considerations p. 24
5.4.6 Multiplexer Control Channel p. 24
5.4.6.1 Message format p. 24
5.4.6.2 Operating procedures p. 25
5.4.6.3 Message Type and Actions p. 25
5.4.6.3.1 DLC parameter negotiation (PN) p. 25
5.4.6.3.2 Power Saving Control (PSC) p. 27
5.4.6.3.3 Multiplexer close down (CLD) p. 27
5.4.6.3.4 Test Command (Test) p. 28
5.4.6.3.5 Flow Control On Command (FCon) p. 28
5.4.6.3.6 Flow Control Off Command (FCoff) p. 28
5.4.6.3.7 Modem Status Command (MSC) p. 28
5.4.6.3.8 Non Supported Command Response (NSC) p. 30
5.4.6.3.9 Remote Port Negotiation Command (RPN) p. 31
5.4.6.3.10 Remote Line Status Command(RLS) p. 34
5.4.6.3.11 Service Negotiation Command (SNC) p. 34
5.4.7 Power Control and Wake-up Mechanisms p. 36
5.4.8 Flow Control p. 37
5.5 Convergence Layers p. 38
5.5.1 Type 1 - Unstructured Octet Stream p. 38
5.5.2 Type 2 - Unstructured Octet Stream with flow control, break signal handling and transmission of V.24 signal states p. 39
5.5.3 Type 3 - Uninterruptible Framed Data p. 40
5.5.4 Type 4 - Interruptible Framed Data p. 41
5.6 DLCI Values p. 41
5.7 System Parameters p. 42
5.7.1 Acknowledgement Timer (T1) p. 42
5.7.2 Maximum Frame Size (N1) p. 42
5.7.3 Maximum number of retransmissions (N2) p. 42
5.7.4 Window Size (k) p. 42
5.7.5 Response Timer for multiplexer control channel (T2) p. 42
5.7.6 Response Timer for wake-up procedure(T3) p. 42
5.8 Start-up and close-down of multiplexer p. 43
5.8.1 Start-up procedure p. 43
5.8.2 Close-down procedure p. 43
6 Error Recovery Mode Option p. 43
6.1 Frame Types p. 43
6.1.1 Information transfer, I, command and response p. 43
6.1.2 Receive ready, RR, command and response p. 44
6.1.3 Receive not ready, RNR, command and response p. 44
6.1.4 Reject, REJ, command and response p. 44
6.2 Procedure and State p. 44
6.2.1 Frame state variables and sequence numbers p. 44
6.2.1.1 General p. 44
6.2.1.2 Send state variable V(S) p. 44
6.2.1.3 Send sequence number N(S) p. 44
6.2.1.4 Receive state variable V(R) p. 45
6.2.1.5 Receive sequence number N(R) p. 45
6.2.1.6 Use of the P/F bit to assist in error recovery p. 45
6.2.2 Exchange of information (I) frames p. 45
6.2.2.1 Sending I frames p. 45
6.2.2.2 Receiving I frames p. 45
6.2.2.3 Reception of incorrect frames p. 46
6.2.2.4 Station receiving acknowledgements p. 46
6.2.2.5 Exception conditions and recovery p. 46
6.2.2.5.1 Busy p. 46
6.2.2.5.2 N(S) sequence error p. 46
6.2.2.5.3 Poll/final (P/F) bit (checkpoint) recovery p. 47
6.2.2.5.4 REJ recovery p. 47
6.2.2.5.5 SABM Command p. 47
6.2.2.5.6 DISC Command p. 47
A Advice to TE software implementers p. 48
B Explanatory notes on the CRC Calculation p. 49
$ Change History p. 52
