Abstract: Simple close form expressions for STTD's theoretical performance with or without channel estimation error in flat Rayleigh channel are derived. Simulation comparison between STTD and the two closed loop transmit diversity modes shows that when the maximal Doppler frequency is small the closed loop modes have better performance, but when the Doppler frequency increases this doesn't hold. STTD tends to have a better performance in that case.

Key words: WCDMA, STTD transmit diversity, pairwise error probability, flat Rayleigh channel