Tight Approximate Bounds on Bit Error Rate for Full-Rate Differentially Encoded Cooperative Communications

In this paper, we propose tight approximate bounds on the averaged bit error rate (BER) for differentially cooperative communications achieving full rate in three-user scenario. Under a fixed amplify-and-forward (AF) protocol with fixed transmission rate and power constraints, the proposed approximate bounds are tight to the exact BER in fairly-high signal-to-noise ration (SNR) regimes. Furthermore, the computational complexity of the proposed bounds are significantly lower than the existing bounds. A sub-optimum power allocation for such system is also studied, based on a guideline of an optimum power allocation for a coherent cooperative communication system. Simulation results show superior performance for the sub-optimum power allocation scheme to the equal power allocation one