A cooperative transmission design combining network coding and superposition coding

This paper deals with the design of transmit scheme for the network with two source-destination pairs. A joint network coding (NC) and superposition coding (JNS) scheme is proposed to realize a cooperative transmission between two pairs. The use of NC is able to improve spectral efficiency over classical decode and forward (DF) relaying strategy by relaxing the orthogonality constraint between different data streams and mitigating the resultant interference through precoding /beamforming. In contrast to using the channel state information (CSI) based beamforming scheme which can achieve near-optimal performance but involves huge computational complexity, we propose to design the beamforming vector using the form of superposition coding, such that CSI at the transmitters are not required and the involved computation is greatly reduced. The theoretical analysis and simulation results reveal that the proposed scheme shows throughput and BER performances close to the near-optimal CSIT based scheme, while having a much lower implementation complexity.