An irregular repeat accumulate coded adaptive cooperation scheme based on Orthogonal Superposition Modulation

User Cooperation (UC) is a promising technology to obtain diversity gain at terminals. Superposition Modulation Cooperation (SMC) is a new kind of UC mode exploiting higher order modulation constellation to allow relay node (RN) transmitting his own local data together with the relay data from source node (SN). The throughput outperforms Amplify-and-Forward (AF), Decode-and-Forward (DF) and coded cooperation (CC) when channel state is good. Power allocation (PA) between the local signal and relay signal is crucial for the performance of SMC. An Adaptive Orthogonal Superposition Modulation Cooperation (OSMC) Scheme is designed based on the bit-level Mutual Information (MI) model to minimize the average outage probability of the three-node cooperation system. Moreover, Irregular Repeat Accumulate (IRA) code is introduced to further improve the performance. Theoretical analysis and simulation results indicate that the adaptive OSMC scheme improves the power efficiency significantly.