Adaptive threshold based relay selection for minimum feedback

To enable relay selection in multiple relay network, using an average channel gain is not enough to achieve acceptable performance, but using an instantaneous gain causes undue system overhead due to feedback. In this paper, we propose adaptive threshold based relay selection scheme for minimum feedback to avoid system overhead, where a relay reports if its relay-destination (R-D) instantaneous channel gain is above threshold. A source selects the best relay among those which has the highest source-relay (S-R) instantaneous channel gain, and adjusts adaptive threshold according to an operating signal-to-noise ratio. Exact and upper bound on the symbol error rate are derived for M-PSK signaling, and it is shown that the proposed scheme yields acceptable performance in operating range, though full diversity order is not achieved. The theoretical results presented here are validated through simulation.