Outage-Optimal Power Allocation for Space-Time Cooperative Network Coding with Amplify-and-Forward

To improve the resource utilization of traditional two-way wireless relay system, an optimal power allocation (OPA) algorithm for a space-time cooperative network coding scheme employing amplify-and-forward protocol (AF-ST-CNC) is proposed. The system performance in terms of outage probability and its approximation in high signal-to-noise (SNR) regimes are first derived, and by minimizing the larger outage probability of the two sources with respect to the characteristic of network coding, optimal power factors are obtained for some special cases are presented. The proposed algorithm only needs the average channel gain information and has low computation complexity, which facilitates the practical implementation. Simulation results show that the proposed AF-ST-CNC with OPA algorithm outperforms the AF-ST-CNC with equal power allocation (EPA) algorithm and the space-time cooperative network coding scheme employing amplify-and-forward protocol (DF-ST-CNC) with OPA algorithm in terms of outage performance.