Abstract: In order to mitigate the effect of asynchronism between users and reduce the complexity of the receiver, an asynchronous differential space-time cooperation scheme is presented. Binary phase-shift keying (BPSK) information symbols are divided into two parts and differential-modulated on the in-phase axis (I axis) and quadrature-phase axis (Q axis) respectively, and then coded with the time-reversal space-time block code (TR-STBC). The receiver decodes the signal with the similar method of differential space-time block code (DSTBC), and the decoded signals on the I axis and Q axis are two separate parts of the transmit signal without the asynchronous effect. Through the analysis and simulation of the BER, we demonstrate that the scheme can still achieve cooperative diversity in an asynchronous condition.

Key words: cooperation diversity, selection relaying protocol, differential space-time block code, time-reversal space-time block code