Adaptive relay selection for hybrid relay systems

Hybrid relay systems using Amplify-and-Forward protocol (AF) and Decode-and-Forward protocol (DF) together are introduced in cooperative networks. For hybrid systems, we propose adaptive relay selection scheme to maximize the overall received Signal to Noise Ratio (SNR) at the destination. At first two relays are selected among many according to the instantaneous channel conditions. One is a relay to operate as the Amplify-and-Forward protocol and the other is a relay to operate as the Decode-and-Forward protocol. Next the total transmission power is allocated to the source and two selected relays. Simulation results show that the proposed scheme achieves better performance than that of conventional cooperative schemes.