Performance analysis of distributed space-time codes in amplify-and-forward mode

The idea of space-time coding, devised for multiple-antenna systems, can be applied to communication over a wireless relay network in amplify-and-forward (AF) mode. In this paper, we propose a distributed space-time protocol in which source node contributes in transmitting information as a virtual relay, for a general R-relay system. This system does not require channel state information at relays. Our simulation results show that we get significant performance gain, when the source to destination link is also employed for transmitting information. Furthermore, assuming MPSK and MQAM modulation and maximum likelihood (ML) detection, we derive a formula for the bit error probability of the investigated schemes in Rayleigh fading channels. Our analytical results have been confirmed by simulation results, using full-rate, full-diversity distributed codes.