Analysis of the channel bit-rate detection process in WCDMA

A critical task within receivers for third-generation W-CDMA systems is the detection of the respective channel parameters and bit-rate on the basis of decoding the transport format combination indicator (TFCI) bits associated with each 10 ms frame. Evaluation of hard and soft decoding of the TFCI bits is therefore the focus of this work. The probability of erroneous rate detection for each case is computed and supported by simulation results obtained in realistic scenarios specified by the 3GPP standardisation forum. It is shown that the improved performance provided by soft decoding over hard detection is in the range of 2 to 3 dB for a wide range of signal-to-interference-plus-noise ratios, and that for low data rates, where fewer TFCI bits are transmitted per slot, the decoding performance is inferior to that in high data rates.