Relay selection for two‐way opportunistic relaying with outdated Nakagami‐m estimates

Abstract

AbstractOpportunistic relay selection (RS) is an efficient method to obtain diversity gain in two‐way relaying protocol with multiple relays. However, in practical wireless networks, the channel state information (CSI) used in the RS procedure becomes outdated because of the feedback delay, which severely deteriorates the system performance. In this paper, we study the RS strategies that aim to optimise the system outage performance of two‐phase two‐way opportunistic relaying protocol in Nakagami‐m channels. RS schemes for two different cases are designed, that is, (i) the scheme with only the outdated CSI during the RS procedure and (ii) the scheme with both the outdated CSI and the statistical knowledge of channels during the RS procedure. The system outage performance and the achievable diversity for the proposed schemes are analysed theoretically. It is shown that the RS schemes that use the statistical knowledge of channels can not only provide improvement in outage probability but also harvest diversity gain. Simulation results are presented to evaluate the performances while validating the theoretical analyses for the proposed schemes. Copyright © 2014 John Wiley & Sons, Ltd.