A Multihop Transmission Scheme With Detect-and-Forward Protocol and Network Coding in Two-Way Relay Fading Channels

In this paper, we propose and analyze a multihop transmission scheme based on detect-and-forward (DF) relay protocol and network coding (NC) for two-way relay channels. In this scheme, the odd relays perform hard detection and then forward the detected signals to the next hop, whereas the even relays perform NC on the detected signals from the two adjacent nodes and broadcast them to the next hop. By separating the network into multiple two-hop subsystems, we develop closed-form expressions for bit error rate (BER) in flat Rayleigh fading channels. Our results are given as both lower bound and asymptotic expression based on an accurate upper bound of the end-to-end signal-to-noise ratio (SNR). It is shown that the proposed scheme has the same asymptotic BER performance and a much higher throughput compared with the conventional bidirectional relay scheme based on four transmission phases. Therefore, the proposed scheme is efficient for practical wireless applications. Simulation results are provided to validate the analysis.