Performance analysis of a DSTTD system with decision-feedback detection

We investigate closed-form bit error rate (BER) expressions for the double space-time transmit diversity (DSTTD) system with a zero-forcing decision-feedback (ZF-DF) detector. We show that the lower Alamouti's STTD unit can obtain the second order diversity gain. However, the upper one cannot guarantee the fourth order diversity due to the effect of error propagation. For example, it simply gives 3.5 dB signal-to-noise ratio (SNR) advantage over the lower one at the bit error rate (BER) of 10(-3). Under the same environment, overall BER performance also suffers from 5.6 dB performance degradation over a maximum likelihood (ML) detector.