On Optimum Regenerative Relaying With Imperfect Channel Knowledge

This correspondence is concerned with the performance of a regenerative relaying protocol on fading wireless channels with imperfect channel knowledge at the receivers. Assuming a single source and a single destination with multiple relay nodes, using binary modulation at the source, we present optimum receiver at the destination on frequency-flat Rayleigh fading channels by taking into account the effects of imperfect channel knowledge at the receivers. Since exact performance analysis of the optimal receiver is complicated due to the non-linear nature of the log-likelihood ratio contribution from the relay, upon using a standard technique in the literature, we present a simple approximate receiver and derive closed-form expression for the average bit error rate (BER) at the destination with a single relay node. We also present a simple analytical technique that allows us to numerically evaluate the average BER for an arbitrary number of relay nodes. Finally, with perfect channel estimation our proposed receiver subsumes the coherent receivers whereas with a minimum mean-square error channel estimation it reduces to the non-coherent receiver in the work of Chen and Laneman (2006).