Performance Evaluation for the Cooperative Communication Systems in Decode-and-Forward Mode with a maximal ratio combining scheme

Cooperative system is a tendency in the future communications because it provides a spatial diversity to improve the system performance. Three strategies including Amplify-and-Forward (AF) mode, Decode-and-Forward (DF) mode and Compress and Forward (CF) mode could be candidate to be employed in the system. This work considers the cooperative communication systems in DF Mode. The scenario includes one source station, M relay stations and N destinations. For the whole system, the maximum throughput approaching is the major purpose in this work. Hence, to select the relay stations for signal transmission could be the important scheme to achieve the best system performance. Based on the exhaustive search method, easily to realize, the optimal selection scheme could be found with a highly complicated calculation. In order to reduce the computational complexity, a sub-optimal solution with a greedy algorithm applied for the relay selection scheme is proposed. With different situations of the communication systems, the performances evaluations obtained by both the proposed algorithm and the exhaustive search method are given for comparison. It shows the proposed algorithm could provide a solution approaches to the optimal one. It is better to apply the proposed scheme when the number of relay stations is much larger than that of destination stations. Key-Words: Cooperative communication, Relay selection, Decode-and-Forward (DF) mode, Exhaustive search, Greedy algorithm