Determination of Impact of Imperfect Feedback Over Distributed Wireless Relay Selection

Space-time coding has the potential to achieve significant diversity gain without having channel state information at the transmitter. We apply this idea over distributed wireless relay network combined with quantized feedback. In this work, we propose and analyse the performance of imperfect feedback-based relay selection schemes employing decode and forward protocol. The feedback bit helps to select the precoder matrix at the relay node for power allocation according to the channel gain. However, a wrong relay channel may get selected due to the unguided nature of the wireless feedback link which degrades the overall performance of the considered system. Therefore, two error-tolerant weighting schemes are implemented over the considered wireless cooperative network. The exact and asymptotic expressions of the outage probability are calculated while considering imperfect feedback. The out-age performance comparison of the considered schemes over Nakagami-m faded channel with other equal power allocation and best relay selection (with and without feedback error) schemes are also investigated. It is evident from the numerical results that the considered error-tolerant schemes remain insensitive to the feedback error and provide noticeable gain.