Mitigating error propagation with an adaptive detect-and-forward strategy in cooperative relay channels

This paper proposes a simple relaying protocol, namely Adaptive Detect-and-Forward (ADeF), for dual-hop transmissions in cooperative networks. In ADeF, relay nodes forward the received signal if the reliability information satisfies a predetermined threshold level. This simple strategy can adaptively select the symbols that are most reliable to the destination, and thus mitigate error propagation from noisy relays. We investigate two-hop relay schemes which implement only a hard-decision detect-and-forward (DeF) at relays. We examine the bit error rate (BER) performance for the proposed strategies against the baseline DeF through Monte Carlo simulations. We also suggest a list of threshold levels which provides optimal BER performance improvements. We find that the proposed schemes can obtain a considerable performance gain against the baseline scheme by using this simple reliability threshold at relays.