SIST EN 301 707 V7.2.1:2003
(Main)Digital cellular telecommunications system (Phase 2+) (GSM); Discontinuous Transmission (DTX) for Adaptive Multi-Rate (AMR) speech traffic channels (GSM 06.93 version 7.2.1 Release 1998)
- Abstract
Adaptive Multi- Rate (AMR) Comfort noise
- Status
- Published
- Publication Date
- 30-Nov-2003
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Dec-2003
- Due Date
- 01-Dec-2003
- Completion Date
- 01-Dec-2003
- Mandate
- T-172
SIST EN 301 707 V7.2.1:2003 is the Slovenian adoption of EN 301 707 Version 7.2.1, a European telecommunications standard from ETSI for Digital cellular telecommunications system (Phase 2+) (GSM). It specifies Discontinuous Transmission (DTX) for Adaptive Multi-Rate (AMR) speech traffic channels, covering how GSM Mobile Stations (MS) and Base Station Systems (BSS) handle speech bursts, comfort noise, and frame types on the transmit and receive paths. In practice, it tells implementers how to reduce transmission during pauses without changing what the air interface and speech decoder output must do.
What does SIST EN 301 707 V7.2.1:2003 specify?
SIST EN 301 707 V7.2.1:2003 specifies the general baseband operation of AMR speech traffic channels during DTX in the transmitter and receiver of GSM MSs and BSSs. It also defines how DTX handling is structured around the transmit side, receive side, and a small informative change-history annex.
| Annex | What it covers |
|---|---|
| Annex A | Document change history |
The scope says the functional split shown in the figures is for clarity, but implementation may use other internal arrangements if the air interface and speech decoder output behave the same. For some BSS arrangements, especially where the speech transcoder is remote from the BTS, the interface between the DTX handlers and the Radio Sub System (RSS) is mandatory because it forms part of the A-bis interface.
What are the key requirements of SIST EN 301 707 V7.2.1:2003?
SIST EN 301 707 V7.2.1:2003 makes DTX mandatory in GSM MSs, and the receiver requirements mandatory in all GSM BSSs. The transmitter requirements are mandatory where downlink DTX or Tandem Free Operation (TFO) is used.
Transmit-side control
On the TX side, the Voice Activity Detector (VAD) runs continuously and drives the TX DTX handler. When VAD indicates speech, the frame is passed on as speech; when speech ends, the handler keeps sending speech-marked frames for a hangover period, then sends SID_FIRST and later periodic SID_UPDATE frames to refresh comfort noise. This matters because the receiver needs regular comfort-noise updates rather than silence alone.
Frame marking and scheduling
The TX DTX handler uses TX_TYPE to mark frames such as SPEECH_GOOD, SID_FIRST, SID_UPDATE, ONSET, and NO_DATA. The radio subsystem uses TX_TYPE to decide whether to code and transmit a frame, skip it, or prepare special frame formats. In practice, this is how the implementation controls what is actually sent over the air or between transcoder and base station.
TCH/AFS and TCH/AHS behavior
For TCH/AFS, the standard distinguishes speech, SID, and no-data handling and describes how ONSET can precede a new speech burst. For TCH/AHS, it adds special inhibited and partitioned SID frame formats and different transmission handling. This matters because the same DTX idea is applied differently depending on the traffic channel type.
Downlink TFO and corrupted frames
When TFO is ongoing, the BTS still applies DTX handling on the downlink path. The standard also defines special handling for SPEECH_DEGRADED, SPEECH_BAD, SID_BAD, and SID_FILLER, including deliberate CRC inversion to trigger error concealment in the MS. This preserves intelligibility when frames are damaged or replaced.
Receive-side classification and modes
On the RX side, the RSS classifies received frames into RX_TYPE categories such as SPEECH_GOOD, SPEECH_DEGRADED, SPEECH_BAD, SID_FIRST, SID_UPDATE, SID_BAD, ONSET, and NO_DATA. The RX DTX handler then operates in either SPEECH or COMFORT_NOISE mode. That separation tells implementers when to decode speech directly and when to generate comfort noise or apply substitution and muting.
Handover and synchronisation
The standard requires TX/RX DTX handler synchronisation at handover, using the NSYNC control parameter. This is important because a handover can otherwise break the timing of SID updates and comfort-noise state.
What terms does SIST EN 301 707 V7.2.1:2003 define?
- frame - A 20 ms time interval used by the AMR speech transcoder and also as a short term for a traffic frame.
- traffic frame - A block of information bits carried on TCH/AFS or TCH/AHS speech traffic channels.
- SID frame - A frame with SID bit patterns that can convey acoustic background-noise information.
- VAD flag - A binary output from VAD showing whether speech is present in the current frame.
- TX_TYPE - A transmit-side flag that tells the radio subsystem what kind of frame is being handled.
- RX_TYPE - A receive-side flag that tells the RX DTX handler what kind of frame the receiver has identified.
- hangover period - The 7-frame period after speech ends during which the transmitter still sends speech-marked frames.
- DTX - Discontinuous Transmission, the mechanism that switches the radio transmitter off during speech pauses.
Who uses SIST EN 301 707 V7.2.1:2003?
This standard is used by GSM MS and BSS implementers, especially teams designing the AMR speech path, VAD logic, comfort-noise generation, and radio-subsystem frame handling. It is also used by BTS, BSC, and transcoder vendors, and by test and quality teams checking handover behavior, frame classification, and DTX operation on TCH/AFS and TCH/AHS.
What changed in SIST EN 301 707 V7.2.1:2003 from the previous edition?
Annex A records the change history leading to Version 7.2.1. The listed changes include a revised SID update rate for AMR on TCH/AFS, handling of SPARE and NO_DATA RX_TYPEs, introduction of RATSCCH and TFO for AMR, a correction to the RX_TYPE identifier, and uplink RX/TX DTX handler synchronisation at handover. The document is then issued as Version 7.2.1 for publication.
Which standards are used with SIST EN 301 707 V7.2.1:2003?
SIST EN 301 707 V7.2.1:2003 references these GSM and ETSI documents to define the surrounding speech, radio, and control functions:
- GSM 01.04 - abbreviations and acronyms.
- GSM 04.08 - mobile radio interface layer 3, including network control of DTX.
- GSM 05.03 - channel coding and frame formats.
- GSM 05.05 - radio transmission and reception.
- GSM 05.08 - radio subsystem link control.
- GSM 05.09 - link adaptation, including RATSCCH.
- GSM 06.71, 06.73, 06.74, 06.90, 06.91, 06.92, 06.94 - AMR processing, code, test vectors, transcoding, frame substitution and muting, comfort noise, and VAD.
- GSM 08.60, 08.61, 08.62 - remote transcoder control and TFO.
What does the SIST EN 301 707 V7.2.1:2003 document contain?
The document contains two block diagrams showing the TX and RX DTX functions, plus tables that identify TX_TYPE and RX_TYPE values and their roles. It also gives the normal hangover procedure, the rules for SID_FIRST and periodic SID_UPDATE generation, and the handling of TCH/AFS, TCH/AHS, TFO, and RATSCCH cases. For verification work, the figures and tables show how to trace each frame from VAD decision to radio transmission and comfort-noise generation.
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Frequently Asked Questions
SIST EN 301 707 V7.2.1:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Digital cellular telecommunications system (Phase 2+) (GSM); Discontinuous Transmission (DTX) for Adaptive Multi-Rate (AMR) speech traffic channels (GSM 06.93 version 7.2.1 Release 1998)". This standard covers: Adaptive Multi- Rate (AMR) Comfort noise
Adaptive Multi- Rate (AMR) Comfort noise
SIST EN 301 707 V7.2.1:2003 is classified under the following ICS (International Classification for Standards) categories: 33.070.50 - Global System for Mobile Communication (GSM). The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 301 707 V7.2.1:2003 is associated with the following European legislation: Standardization Mandates: T-172. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
SIST EN 301 707 V7.2.1:2003 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHP ID]D ±1H]YH]QRRGGDMDQMH '7;
SULSULODJRGOMLYLKYHþKLWURVWQLK $05 JRYRUQLKSURPHWQLKNDQDOLK *60
UD]OLþLFDL]GDMD
Digital cellular telecommunications system (Phase 2+) (GSM); Discontinuous
Transmission (DTX) for Adaptive Multi-Rate (AMR) speech traffic channels (GSM 06.93
version 7.2.1 Release 1998)
Ta slovenski standard je istoveten z: EN 301 707 Version 7.2.1
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
ETSI EN 301 707 V7.2.1 (2000-04)
European Standard (Telecommunications series)
Digital cellular telecommunications system (Phase 2+);
Discontinuous Transmission (DTX) for Adaptive Multi-Rate
(AMR) speech traffic channels
(GSM 06.93 version 7.2.1 Release 1998)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
(GSM 06.93 version 7.2.1 Release 1998) 2 ETSI EN 301 707 V7.2.1 (2000-04)
Reference
REN/SMG-110693Q7R1
Keywords
Digital cellular telecommunications system,
Global System for Mobile communications
(GSM), AMR
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© European Telecommunications Standards Institute 2000.
All rights reserved.
ETSI
(GSM 06.93 version 7.2.1 Release 1998) 3 ETSI EN 301 707 V7.2.1 (2000-04)
Content
Intellectual Property Rights.4
Foreword .4
1 Scope.5
2 References.5
3 Definitions, symbols and abbreviations .6
3.1 Definitions.6
3.2 Symbols.6
3.3 Abbreviations .6
4 General .7
4.1 General organisation.7
5 Transmit (TX) side.8
5.1 General operation .8
5.1.1 Functions of the TX DTX handler .9
5.1.2 Functions of the TX Radio Subsystem.10
5.1.2.1 Functions of the TX Radio Subsystem for TCH/AFS .10
5.1.2.2 Functions of the TX Radio Subsystem for TCH/AHS.10
5.1.2.3 Functions of the Downlink TX Radio Subsystem for TFO .11
5.1.2.4 Functions of the TX Radio Subsystem for RATSCCH .11
6 Receive (RX) side .12
6.1 General operation .12
6.1.1 Functions of the RX radio subsystem .12
6.1.2 Functions of the RX DTX handler.13
Annex A (informative): Document change history.14
History.15
ETSI
(GSM 06.93 version 7.2.1 Release 1998) 4 ETSI EN 301 707 V7.2.1 (2000-04)
Intellectual 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 ETSI members and non-members, and can be found
in 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
(http://www.etsi.org/ipr).
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 SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by the Special Mobile Group (SMG).
The present document describes the general baseband operation of Adaptive Multi-Rate speech traffic channels in the
transmitter and in the receiver of GSM Mobile Stations and Base Station Systems during Discontinuous Transmission
(DTX) within the digital cellular telecommunications system.
The present document corresponds to GSM technical specification, GSM 06.93 AMR, version X.X.X.
The contents of the present document is subject to continuing work within SMG and may change following formal SMG
approval. Should SMG modify the contents of the present document it will be re-released with an identifying change of
release date and an increase in version number as follows:
Version 7.x.y
where:
7 indicates Release 1998 of GSM Phase 2+.
x the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections, updates,
etc.
y the third digit is incremented when editorial only changes have been incorporated in the specification.
National transposition dates
Date of adoption of this EN: 31 March 2000
Date of latest announcement of this EN (doa): 30 June 2000
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 December 2000
Date of withdrawal of any conflicting National Standard (dow): 31 December 2000
ETSI
(GSM 06.93 version 7.2.1 Release 1998) 5 ETSI EN 301 707 V7.2.1 (2000-04)
1 Scope
The present document gives a description of the general baseband operation of Adaptive Multi-Rate speech traffic
channels in the transmitter and in the receiver of GSM Mobile Stations (MS)s and Base Station Systems (BSS)s during
Discontinuous Transmission (DTX).
For clarity, the description is structured according to the block diagrams in figures 1 and 3. Except in the case described
next, this structure of distributing the various functions between system entities is not mandatory for implementation, as
long as the operation on the air interface and on the speech decoder output remains the same.
In the case of BSSs where the speech transcoder is located remote from the Base Transceiver Station (BTS), the
implementation of the interfaces between the DTX handlers and the Radio Sub System (RSS) as described in the present
document together with all their flags is mandatory, being part of the A-bis interface as described in GSM 08.60 and
GSM 08.61.
The DTX functions described in this technical specification are mandatory for implementation in the GSM MSs. The
receiver requirements are mandatory for implementation in all GSM BSSs, the transmitter requirements only for those
where downlink DTX or Tandem Free Operation will be used.
2 References
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.
• A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
• For this Release 1998 document, references to GSM documents are for Release 1998 versions (version 7.x.y).
[1] GSM 01.04: "Digital cellular telecommunication system (Phase 2+); Abbreviations and acronyms".
[2] GSM 04.08: "Digital cellular telecommunication system (Phase 2+); Mobile radio interface layer 3
specification".
[3] GSM 05.03: "Digital cellular telecommunication system (Phase 2+); Channel coding".
[4] GSM 05.05: "Digital cellular telecommunication system (Phase 2+); Radio transmission and
reception".
[5] GSM 05.08: "Digital cellular telecommunication system (Phase 2+); Radio subsystem link
control".
[6] GSM 05.09: "Digital cellular telecommunication system (Phase 2+); Link adaptation".
[7] GSM 06.71: "Digital cellular telecommunications system (Phase 2+); Adaptive Multi-Rate (AMR)
speech processing functions; General description".
[8] GSM 06.73: "Digital cellular telecommunications system (Phase 2+); ANSI-C code for the GSM
Adaptive Multi-Rate speech codec".
[9] GSM 06.74: "Digital cellular telecommunications system (Phase 2); Test vectors for the GSM
Adaptive Multi-Rate speech codec".
ETSI
(GSM 06.93 version 7.2.1 Release 1998) 6 ETSI EN 301 707 V7.2.1 (2000-04)
[10] GSM 06.90: "Digital cellular telecommunications system (Phase 2+); Adaptive Multi-Rate speech
transcoding".
[11] GSM 06.91: "Digital cellular telecommunications system (Phase 2+); Substitution and muting of
lost frame for Adaptive Multi-Rate speech traffic channels".
[12] GSM 06.92: "Digital cellular telecommunications system (Phase 2+); Comfort noise aspects for
Adaptive Multi-Rate speech traffic channels".
[13] GSM 06.94: "Digital cellular telecommunications system (Phase 2+); Voice Activity Detector
(VAD) for Adaptive Multi-Rate speech traffic channels".
[14] GSM 08.60: "Digital cellular telecommunication system (Phase 2+); Inband control of remote
transcoders and rate adaptors for Full Rate traffic channels".
[15] GSM 08.61: "Digital cellular telecommunication system (Phase 2+); Inband Control of Remote
Transcoders and Rate Adaptors for Half Rate traffic channels".
[16] GSM 08.62: "Digital cellular telecommunications system; Inband Tandem Free Operation (TFO)
of Speech Codecs".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
frame: Time interval of 20 ms, corresponding to the time segmentation of the Adaptive Multi Rate speech transcoder
(GSM 06.90 [9]), also used as a short term for a traffic frame.
traffic frame: Block of 95.244 information bits transmitted on the TCH/AFS or TCH/AHS speech traffic channels.
SID frame: Frame characterised by the SID (Silence Descriptor) gross bit patterns. It may convey information on the
acoustic background noise.
speech frame: Traffic frame that has been classified as a SPEECH frame.
VAD flag: Boolean flag, generated by the VAD algorithm defined in GSM 06.94 indicating the presence ("1") or the
absence ("0") of a speech frame.
RX_TYPE: flag with eight values, generated by the RX radio subsystem, indicating to the RX DTX handler the type of
data in the current frame. Refer to Table 2.
TX_TYPE: flag with eight values, generated by the TX DTX handler, indicating to the TX radio subsystem the type of
data in the current frame. Refer to Table 1.
hangover period: A period of 7 frames added at the end of a speech burst in which VAD flag ="0" and TX_TYPE is
"SPEECH".
3.2 Symbols
For the purposes of the present document, the following symbols apply:
N Number of elapsed frames since the last updated SID frame.
elapsed
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ETSI
(GSM 06.93 version 7.2.1 Release 1998) 7 ETSI EN 301 707 V7.2.1 (2000-04)
BSC Base Station Controller
BSS Base Station System
BTS Base Transceiver Station
CHD Channel Decoder
CHE Channel Encoder
DTX Discontinuous Transmission
ETS European Telecommunication Standard
FACCH Fast Associated Control CHannel
GSM Global System for Mobile Telecommunications
MS Mobile Station
RATSCCH Robust Amr Traffic Synchronised Control CHannel
RSS Radio Sub System
RX Receive
SACCH Slow Associated Control CHannel
SID SIlence Descriptor
TX Transmit
VAD Voice Activity Detector
For abbreviations not given in this subclause, see GSM 01.04.
4 General
Discontinuous Transmission (DTX) is a mechanism, which allows the radio transmitter to be switched off most of the
time during speech pauses for the following two purposes:
- to save power in the Mobile Station (MS);
- to reduce the overall interference level over the air interface.
DTX in uplink shall be in operation within the GSM MS, if commanded so by the network, see GSM 04.08. The MS
shall handle DTX in downlink at any time, regardless, whether DTX in uplink is commanded or not.
4.1 General organisation
The overall DTX mechanism described in the present document requires the following functions:
- a Voice Activity Detector (VAD) on the transmit (TX) side;
- evaluation of the background acoustic noise on the transmit (TX) side, in order to transmit characteristic
parameters to the receive (RX) side;
- generation on the receive (RX) side of a similar noise, called comfort noise, during periods where the radio
transmission is switched off.
The Voice Activity Detector (VAD) is defined in GSM 06.94 and the comfort noise functions in GSM 06.92. Both are
based partly on the speech transcoder and its internal variables, defined in GSM 06.90.
In addition to these functions, if the parameters arriving at the RX side are detected to be seriously corrupted by errors,
the speech or comfort noise must be generated from substituted data in order to avoid seriously annoying effects for the
listener. This function is defined in GSM 06.91.
An overall description of the speech processing parts can be found in GSM 06.71.
The description for Tandem Free Operation is given in GSM 08.62.
ETSI
(GSM 06.93 version 7.2.1 Release 1998) 8 ETSI EN 301 707 V7.2.1 (2000-04)
5 Transmit (TX) side
A block diagram of the transmit side DTX functions is shown in figure 1.
TX DTX handler TX Radio subsystem
Speech
encoder Information bits
Channel
Encoder
Voice
Mode Indication
Activity
Detector
TX_TYPE
TX_TYPE
Monitoring
Comfort
Noise
Computation
Figure 1: Block diagram of the transmit side DTX functions
5.1 General operation
The TX DTX handler passes traffic frames, individually marked by TX_TYPE, to the Radio Subsystem (RSS). Each
frame passed to the RSS consists of bit fields containing the information bits, the codec mode indication, and the
TX_TYPE. TX_TYPE is used to specify the contents of the frame. The table below provides an overview of the
different TX_TYPEs used and explains the required contents in the information bit and the mode indication bit fields. In
case of ongoing Tandem Free Operation (see GSM 08.62) frames with errors may arrive in downlink in the BTS.
Table 1: TX TYPE identifiers
TX_TYPE Legend Information Bits Mode Indication
SPEECH_GOOD speech frame, size 95.244 bits depending current code mode
on codec mode;
no errors known.
Speech frame, size 95.244 bits, depending current codec mode
SPEECH_DEGRADED
on codec mode;
(only in downlink in
TFO) there might be errors in class 2 bits.
Speech frame, size 95.244 bits, depending current codec mode
SPEECH_BAD
on codec mode;
(only in downlink in
TFO) there are errors in class 1 bi
...