Approximate Outage Probability Expressions for Evaluating Cooperative Communications

Cooperative communication systems have emerged as a significant concept to improve reliability and throughput in wireless systems. Some existing cooperative diversity protocol are shown to increase the diversity order, allowing single-antenna nodes to cooperate and achieve performance like a real MIMO system. In this paper, we focus on improving the precision of analysis of Amplify-and-Forward (AF), Decode-and-Forward (DF) in terms of outage probability. Especially, we derive some approximate expressions of outage probability for these three relaying protocols. The approximate expressions are proved to be better than some existing ones, in other words our approximations are much closer to the truth value. In our research, we use the outage probabilities calculated by Monte Carlo Method (MCM) as the reference for the reason that they are the nearest to the truth value. We show analytically and experimentally that our expressions are better than some existing approximate expressions in low Signal to Noise Ratios (SNR) as well. The simulation results and our analysis can prove the accuracy and concision of the expressions. Besides, the approximate expressions are useful to the analysis of outage probability when we investigate the performance of relaying protocols.