Opportunistic Network-Coded Cooperative Transmission with Demodulate-and-Forward Protocol in Wireless Channels

In this letter, we consider a multiuser cooperative transmission scheme with network coding over wireless channels. Network coding based on decode-and-forward protocol is a promising technique to improve network throughput. However, decoding errors at the relay cause error propagation, which degrades the performance of network-coded cooperations. To mitigate the error propagation in the network-coded signal, we first express a single equivalent gain, and then the opportunistic relay selection and proportional combining schemes are performed with the equivalent channel and the relay-destination channel. Simulation results show that all cooperative users can obtain a diversity gain of order two by using single network-coded transmission, even when there are detection errors at the relay.