On the performance of cooperative communication via best relay path

We design and analyze spectrally efficient half-duplex cooperative diversity protocols using multiple relays (say N), which combat the multi-path fading by retransmitting the bitinterleaved coded information transmitted by a source to destination. In the first proposed protocol, the relay with the best mutual information relay path (source-relay-destination) will relay the source information - thus termed as best-relay protocol. In the second proposed protocol, called N-relay cyclic protocol, each relay will transmit only a portion of the signal transmitted by the source. We derive the probability density functions of the mutual information for both of these protocols and using these densities, we analyze the outage probability and outage capacity performances. The results show that the proposed protocols achieve the maximum diversity order N + 1. The simulation results using turbo code are given and results show the superior performance of the best-relay protocol.