WCDMA/UMTS TB vs TBS vs TTI vs TFC vs TFCS vs TFI vs TFCI terms

This tutorial section on WCDMA (UMTS) basics covers following sub topics:
UMTS Tutorial  UMTS channels  measurements  PHY layer  TDD vs FDD PHY  RRC States  Security  Cell search  Bands  UARFCN  Frame 

This page on WCDMA TB vs TBS vs TTI vs TFC vs TFCS vs TFI vs TFCI provide difference between TB,TBS,TTI,TFC,TFCS,TFI and TFCI WCDMA/UMTS terms. Following are the Transport Formats/Configurations used in WCDMA/UMTS technologies.

Transport Block (TB)

Basic unit of data exchanged between L1 & MAC for L1 processing Transport Block Size: Number of bits in a TB.

Transport Block Set (TBS)

A set of TBs exchanged between L1 and MAC at the same time instant using the same transport channel Transport Block Set Size: Number of bits in a TBS

Transmission Time Interval (TTI)

Periodicity at which a TBS is transferred by the physical layer on to the radio interface - {10, 20, 40, 80 ms} MAC delivers one TBS to the physical layer every TTI.

Transport Format Combination (TFC)

Multiple TrCHs each having a TF. Authorized combination of the currently valid TFs that can be submitted to L1 on a CCTrCH, containing one TF from each TrCH.

Transport Format Combination Set (TFCS)

•  A set of TFCs on a CCTrCH. Produced by RNC.
•  TFCS is given to MAC by L3 for control.
•  MAC chooses between the different TFCs specified in the TFCS.
•  MAC has control over only the dynamic part of the TFs. Semi-static part relates to QoS (e.g., quality) and is controlled by RNC admission control.
•  Bit rate can be changed quickly by MAC with no need to L3 signaling.

Transport Format Indicator (TFI)

A label for a specific TF within a TFS. Used between MAC and L1.

Transport Format Combination Indicator (TFCI)

Used to inform the receiving side of the currently valid TFC.


UMTS Network Architecture
UMTS Protocol Stack
UMTS Logical, Transport and physical channels
UMTS Spreading,scrambling and modulation
WCDMA Compressed mode

RF and Wireless Terminologies