The decision schemes on the concatenation of space-time block code and convolutional code in WCDMA system

This paper discusses the decision issue on the concatenation of space-time block code and convolutional code in WCDMA system. We compare the performance of three decision schemes, i.e., hard-decision, uniform quantization (UQ) soft-decision and adaptive uniform quantization (AUQ) soft-decision over Rayleigh fading channel. Simulation results show that both soft-decision schemes have obviously gain over 1dB than hard-decision. Moreover, if we divide the Rayleigh fading item from the output of space-time block combining, a little more performance gain is possible, thus reaches the soft-decision advantage about 2dB than hard-decision. And because the AUQ scheme changes its quantization scope according to the signal-noise-ratio (SNR), it has extra performance advantage over UQ scheme in fading channel especially at very high or low SNR. However, all of the performance gain is based on increasing the hardware implementation complexity.