Performance Improvement of DSTBC Systems Using Decision Feedback Approach

DSTBC (differential space-time block coding) system does not require CSI (channel state information) in both transmitter and receiver sides, but its SNR (signal to noise ratio) versus BER (bit error rate) characteristic is degraded compared with original STBC scheme which utilizes CSI at the receiver. In this paper, attempting to recover this performance loss originated from the differential decoding, an improved DSTBC system is presented. In the proposed approach, data sequence after the hard decision is fed back and utilized for the channel estimation, and then the noise contained in the received signal is reduced using updated channel information before the differential decoding. Through computer simulations in fading channels assuming mobile applications, it is shown that the improved method could achieve better performance and shows higher tolerance to Doppler effect compared to conventional DSTBC.