Cooperative hybrid-ARQ protocol with network coding

A novel cooperative Hybrid-ARQ protocol was presented on the basis of network coding (C-HARQ-NC). Two users communicated with the base station with the assistance of a relay node. Relay node responded the repeat request and processed two users´ incremental redundancy frames with physical-layer network coding, i.e. signal superposition modulation, before transmitting to the base station. Multi-user joint detection and joint soft decision decoding were adopted at the base station. Compared with traditional Hybrid-ARQ protocol, the C-HARQ-NC protocol can achieve better performance on flat Rayleigh fading channel, and approximates the performance of cooperative Hybrid-ARQ protocol without network coding with fewer hardware and bandwidth resources.