Improvement of Complex Field Network Coding for Cooperative Networks

Complex field network coding (CFNC) is a new network coding approach proposed to improve network throughput and achieve full diversity gain in wireless networks. In view of that CFNC in cooperative networks with parallel relays leads to larger transmission delay and detection complexity at destination nodes, an improved CFNC scheme for(N_S,N_R,1) cooperative network is presented. More specifically, N_S sources send signals to N_R relays and destination simultaneously in time slot 1. In time slot 2, each relay detects and encodes the N_S source symbols with network coding, and then N_R relays send the N_R coded symbols to destination simultaneously. Based on the symbols received from sources and relays in two time slots, joint maximum likelihood detection is adopted at destination to obtain the N_S source symbols. Theoretic analysis demonstrate that, the improved CFNC scheme can obtain the same network throughput and diversity gain as CFNC, while it can decrease the transmission delay of source symbols, and reduce the detection complexity of destination.