TS 101 504 : 8.0.1

Intellectual Property Rights
Foreword
1 Scope
2 References
3 Definitions and Abbreviations
  3.1 Definitions
  3.2 Abbreviations
4 General Approach
  4.1 Background
  4.2 Principle of Tandem Free Operation
5 TFO Frame Structure
  5.1 TFO Frames for Full Rate and Enhanced Full Rate
  5.2 TFO Frame for Half Rate
6 TFO Message Structure
  6.1 Extendibility
  6.2 Regular and Embedded TFO Messages
  6.3 Cyclic Redundancy Check
  6.4 Definition of the TFO_REQ Messages
  6.5 Definition of the TFO_ACK Messages
  6.6 Definition of the TFO_TRANS Messages
  6.7 Definition of the TFO_NORMAL Message
  6.8 Definition of the TFO_FILL Message
  6.9 Definition of the TFO_DUP Message
  6.10 Definition of the TFO_SYL Message
  6.11 Specification of the TFO Messages for GSM
7 Time Alignment of TFO Frames and TFO Messages
  7.1 Time Alignment of TFO Messages
  7.2 Time Alignment of TFO Frames
  7.3 Time Alignment of TFO Frames to Downlink TRAU
      Frames
8 Processes for Tandem Free Operation
  8.1 Rx_TRAU Process
  8.2 Tx_TRAU Process
  8.3 Tx_TFO Process
  8.4 Rx_TFO Process
  8.5 TFO_Protocol Process
9 State Machine of the TFO_Protocol Process
  9.1 Initialisation
  9.2 Establishment
  9.3 Contact State
  9.4 Konnect State
  9.5 Operation State
  9.6 Local Handover
  9.7 Distant Handover, TFO Interruption
  9.8 Failure State
10 Detailed Description of TFO_Protocol
11 Codec Mismatch Resolution and Codec Optimization
Annex A (Normative): Inband Signalling Protocol:
                     Generic Structure
                     A.1 Generic Structure of Inband
                         Signalling Messages
                     A.2 Detailed Specification of
                         IS Messages
                     A.3 Keep_Open_Indication
                     A.4 Rules for Sending of IS Messages
                     A.5 IS_System_Identification_Block
Annex B (Informative): In Path Equipment: Generic Rules and
                       Guidelines
                       B.1 Types of In Path Equipment
                       B.2 IS_Compliant IPEs
                       B.3 IPE State Representation
                       B.4 IPE Error Handling
                       B.5 IPE Transmission Delay
                       B.6 Compliance to IS Messages
Annex C (Informative): The SDL model of the TFO protocol
Annex D (informative): Change history
History

Establishes the stage 3 description for the Tandem Free Operation feature which provides the capability to avoid using two GSM speech codecs in mobile to mobile speech calls. The primary aim is to realise improvements in speech quality. The TFO mode of operation could also be used to reduce inter-MSC transmission bandwidth requirements. This service description should be considered together with GSM 08.60 (Inband control of remote transcoders and rate adaptors for Enhanced Full Rate and Full Rate traffic channels) and GSM 08.61 (Inband control of remote transcoders and rate adaptors for Half Rate traffic channels).