  Relay-based cooperative communication has become a research focus in recent
years because it can achieve diversity gain in wireless networks. In existing
works, network coding and two-path relay are adopted to deal with the increase
of network size and the half-duplex nature of relay, respectively. To further
improve bandwidth efficiency, we propose a novel cooperative transmission
scheme which combines network coding and two-path relay together in a
multi-source system. Due to the utilization of two-path relay, our proposed
scheme achieves full-rate transmission. Adopting complex field network coding
(CFNC) at both sources and relays ensures that symbols from different sources
are allowed to be broadcast in the same time slot. We also adopt physical-layer
network coding (PNC) at relay nodes to deal with the inter-relay interference
caused by the two-path relay. With careful process design, the ideal throughput
of our scheme achieves by 1 symbol per source per time slot (sym/S/TS).
Furthermore, the theoretical analysis provides a method to estimate the symbol
error probability (SEP) and throughput in additive complex white Gaussian noise
(AWGN) and Rayleigh fading channels. The simulation results verify the
improvement achieved by the proposed scheme.
