Relay selection utilizing power control for decode-and-forward wireless relay networks

In this paper, we consider a 2-hop wireless relay network where more than one relay is available. We explore optimal relay selection for decode-and-forward cooperative protocol to minimize the outage probability under a short-term power constraint. We first investigate the impact of power control on relay selection from a capacity point-of-view. Assuming the knowledge of channel gain magnitudes, we propose a relay selection strategy utilizing power control. For each candidate relay, its capability of cooperation is evaluated after optimal power allocation between it and the source. The one that maximizes the mutual information between the source and destination is selected for cooperation. A threshold is set to exclude those relays whose cooperation cannot provide performance gain over direct transmission. We also extend the relay selection strategy to the scenario where only network geometry is available. Both theoretical and numerical analyses show the superiority of our relay selection strategies.