Adaptive relay selection and power allocation for hybrid relay systems

Abstract

In this thesis, a hybrid system using Amplify-and-Forward protocol and Decode-and-Forward protocol together is introduced in cooperative networks. For this hybrid system we propose adaptive relay selection and power allocation scheme to maximize the overall received Signal to Noise Ratio(SNR) at the destination node. At first two relays are selected. One is the Decode-and-Forward relay and the other one is the Amplify-and-Forward relay. Next the total transmission power is allocated to the source node and two selected relays according to the instantaneous channel conditions. Simulation results show that the proposed scheme achieves better performance than that of equal power allocation or conventional cooperative schemes. Furthermore, we propose adaptive relay selection and power allocation scheme on individual power constraint of each relay. This proposed algorithm using the weighting factor considers the available power of each relay when relays are selected. System lifetime can be extended by taking this scheme.