Distributed Power Allocation Algorithm for Cooperative Diversity

In this paper,we study the power allocation problem in decode-and-forward cooperative diversity systems.We first present the mathematical model of the power allocation problem,which can minimize the total power consumption of the source and partner under the average bit error rate(BER) constraints at the partner and the destination.Accordingly,the model not only can exploit the inherent spatial diversity in multiuser wireless systems,but also can reduce both the energy consumption of mobile nodes and the cochannel interference in wireless networks.We then derive the BER expressions at the partner and the destination which can characterize the performance of cooperative diversity systems over multipath fading channels.According to the expressions,we propose a distributed power allocation algorithm by which the source,the partner and the destination can compute the optimal power allocation scheme(OPAS) on a message-by-message basis.The proposed algorithm not only has little overhead but also adapts to the changes of channel state.Therefore,the algorithm can conform to the decentralized and dynamic nature of wireless networks.In addition,we present simulations to confirm the proposed algorithm.