4.3 TFO Standard Version Handling

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

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

In TFO Specifications before REL-4 no TFO version handling is defined.

In TFO Specifications of REL-4 an "AMR TFO version number" is defined in the Ver (Version number) field of the AMR_ACS and AMR_SCS Extension Blocks (see clause 7) and the ATVN field in AMR Configuration frames (see Annex C). Only one REL-4 AMR TFO version is defined: version "0".

From REL-5 onwards the "TFO Version number" contained in the "TFO Version" extension block (section 7) and in "Generic Configuration Frames" (Annex H) shall reflect the Version and Subversion of the corresponding TS 28.062 (first and second digit of the TS version number, see foreword). The AMR TFO version number (Ver, AVTN, as in REL-4) shall be treated as "undefined" in case the TFO Version Number (as in REL-5 and onwards) is indicated in the TFO Messages.

The current TFO Version supports the GSM_FR, GSM_HR, GSM_EFR ,five AMR (Narrow Band) speech codec types (FR_AMR, HR_AMR, UMTS_AMR, UMTS_AMR_2, OHR_AMR: AMR-NB family) and four AMR Wide Band speech codec types (FR_AMR-WB, UMTS_AMR-WB, OFR_AMR-WB, OHR_AMR-WB: AMR-WB family).

The smallest defined TFO Version number is 0.0. It stands for all TFO Versions before 5.3. All numbers between 0.0 and 5.3 are reserved for future use. If the Local and Distant version numbers differ, the smallest version number shall have precedence and shall be applied on both sides. The following features (table 4.3-1) are optional or mandatory for the different Codec Types, depending on the applicable version number:

Table 4.3-1: TFO Version Handling

Feature Codec Type	TFO Version	Immediate Codec Type Optimisation	Generic Configuration Frames
GSM_FR GSM_HR GSM_EFR	Optional. The TFO Version extension block need not to be sent. If not contained in TFO Messages, or is lower than 5.3, then Pre-REL-5 handling shall apply	Mandatory, if TFO Version is 5.3 or higher.	If the TFO Version is lower than 5.3 then Generic Configuration Frames shall not be used. Only TFO_REQ_L and (TFO_ACK_L) shall be used. If the TFO Version is 5.3 or higher, then Generic Configuration Frames shall be used. TFO_REQ_L and TFO_ACK_L shall not be used embedded into TFO Frames.
FR_AMR HR_AMR UMTS_AMR UMTS_AMR2 OHR_AMR	Optional. The TFO Version extension block need not to be sent. If not contained in TFO Messages, or is lower than 5.3, then Pre-REL-5 handling shall apply	Mandatory, if TFO Version is 5.3 or higher.	If the TFO Version is lower than 5.3, then Generic ConfigurationFrames shall not be used. If the TFO Version is 5.3 or higher, then Generic Configuration Frames shall be used. The parameter field in REL-4 AMR Configuration frames shall be treated as undefined. TFO_REQ_L and TFO_ACK_L shall not be used embedded into TFO Frames.
FR_AMR-WB UMTS_AMR-WB OFR_AMR-WB OHR_AMR-WB	Mandatory. The TFO Version extension block shall always be sent.	Mandatory.	Generic Configuration Frames shall be used. TFO_REQ_L and TFO_ACK_L shall not be used embedded into TFO Frames.