MAP detection with soft information in an estimate and forward relay network

One proven solution to improve the reliability of a wireless channel is to use relays. We focus on the estimate-and-forward (EF) relay protocol where the relay node estimates the source symbol and then forwards it to the destination. We assume the soft information sent by the relay is the expected value of the symbol transmitted by the source. With bit-error-rate (BER) as a metric, we show that EF outperforms other common relay protocols, in a pathloss model for the cooperative three node wireless network. We use a linear piecewise approximation of the soft information to make the MAP detector tractable and reduce computational complexity.