3 Definitions and abbreviations

28.0623GPPInband Tandem Free Operation (TFO) of speech codecsService descriptionStage 3TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

3.1 Definitions

For the purposes of the present document, the following terms and definitions apply:

Transcoder: device that converts the encoding of information from one particular scheme to a different one

NOTE 1: A Speech Transcoder in a GSM or 3G system converts the speech encoding usually from G.711 [13] to a format optimised for the transmission over the Air Interface. The new format relates to a specific speech Codec.

Tandem Free Operation: call configuration where a transcoder device is physically present in the signal path, but the transcoding functions are bypassed

NOTE 2: The transcoding device may perform control and protocol conversion functions.

Transcoder Free Operation: call configuration where no transcoder device is physically present and hence no control or conversion or other functions associated with it are activated

Compressed Speech Samples: speech samples coded according to one of the Speech Codec Types supported by the TFO specification

PCM Samples: speech samples coded according to ITU-T Recommendation G.711 A-Law or -Law at 64 kbit/s

Speech Codec Type: speech Codec among those supported by this TFO specification: GSM_FR, GSM_HR, GSM_EFR, FR_AMR, HR_AMR, OHR_AMR, UMTS_AMR, UMTS_AMR_2, FR_AMR-WB, UMTS_AMR-WB, OFR_AMR-WB, OHR_AMR-WB

AMR Speech Codec Type: one of the following Speech Codec Types: FR_AMR, HR_AMR, UMTS_AMR, UMTS_AMR_2, FR_AMR-WB, UMTS_AMR-WB, OFR_AMR-WB, OHR_AMR-WB

AMR-NB Speech Codec Type: one of the following Speech Codec Types: FR_AMR, HR_AMR, UMTS_AMR, UMTS_AMR_2, OHR_AMR.

AMR-WB speech Codec Type: one of the following Speech Codec Types: UMTS_AMR-WB, FR_AMR-WB, OFR_AMR-WB, OHR_AMR-WB

Non-AMR Speech Codec Type: one of the following Speech Codec Types: GSM_FR, GSM_HR, or GSM_EFR

Speech Codec Configuration: set of parameters defining the operational conditions of a Speech Codec Type

EXAMPLE: The Speech Codec Configuration of an AMR Speech Codec Type defines the ACS, the SCS…

TRAU Frame or TRAU Speech Frame: refer to a Speech Frame carried over the Abis/Ater Interface in a GSM network

TFO Frame or TFO Speech Frame: refer to the Speech Frames exchanged between the Transcoders when Tandem Free Operation is active

Abis/Ater: applies to a GSM network where either the GSM Abis or Ater interfaces are used, depending on the location of the Transcoder and Rate Adaptor Units

Other definitions are contained in [1] and [3].

3.2 Abbreviations

For the purposes of the present document, the following abbreviations apply:

ACS Active Codec Set

ACT Active Codec Type

AMR Adaptive Multi-Rate

ATVN AMR-TFO Version Number

BSC Base Station Controller

BSS Base Station Sub-system

BTS Base Transceiver Station

CACS Common Active Codec Set

CSCS Common Supported Codec Set

DACS Distant Active Codec Set

DSCS Distant Supported Codec Set

EFR Enhanced Full Rate

FQI Frame Quality Index

FR Full Rate

HOM Hand-Over-Mode

HR Half Rate

IACS Immediate Active Codec Set

ICM Initial Codec Mode

IPE In Path Equipment

LACS Local Active Codec Set

LSB Least Significant Bit

LSCS Local Supported Codec Set

MACS Maximum number of Codecs Modes in the Active Codec Set

MGw Media Gateway

MS Mobile Station

MSB Most Significant Bit

MSC Mobile Switching Centre

NB Narrow-Band

OACS Optimised Active Codec Set

OD Optimal or Distant Configuration requested

OM Optimisation Mode supported

PCM sample 8-bit value representing the A_Law or _Law coded sample of a speech or audio signal; sometimes used to indicate the time interval between two PCM samples (125s).

PCM Pulse_Coded_Modulation

PCM_Alaw_Idle PCM sample with value 0x54

PCM_Alaw_Idle PCM sample with value 0x54.

PCM_Alaw_Silence PCM sample with value 0xD5

PCM_Alaw_Silence PCM sample with value 0xD5.

PCM_Idle either PCM_Alaw_Idle, or PCM_Law_Idle, dependent on application

PCM_Silence either PCM_Alaw_Silence, or PCM_Law_Silence, dependent on application

PCM_Law_Idle PCM sample with value 0x00

PCM_Law_Idle PCM sample with value 0x00.

PCM_Law_Silence PCM sample with value 0xFF

PCM_Law_Silence PCM sample with value 0xFF.

PDU Packet Data Unit

PLMN Public Land Mobile Network

RAN Radio Access Network

RATSCCH Robust AMR Traffic Synchronised Control Channel

RIF Request Indication Flag

RNC Radio Network Controller

SCR Source Controlled Rate

SCS Supported Codec Set

T_Bits Time Alignment Bits

Tbfh Time delay Bad Frame Handling

TC Transcoder

TCME TFO Circuit Multiplication Equipment

TFO Tandem Free Operation

TFO_ACK TFO Acknowledgement Message

TFO_DUP TFO (Half) Duplex Mode Message

TFO_FILL TFO Fill Message

TFO_NORMAL TFO Normal Mode Message

TFO_REQ TFO Request Message

TFO_SYL TFO Sync Lost Message

TFO_TRANS TFO Transparent Mode Message

TRAU Transcoder and Rate Adaptor Unit

TrFO Transcoder Free Operation

TSM TFO Setup Mode

Tultfo Time delay UpLink TFO

UE User Equipment

WB WideBand