Relay Selection for Lifetime Extension in Amplify-And-Forward Cooperative Networks

Prolonging lifetime is of paramount importance for an energy-constrained wireless network to ensure uninterrupted information exchange. Cooperative communication technology, which can achieve high energy-efficiency by exploiting spatial diversity of distributed nodes, has become an attractive way for lifetime extension of wireless networks. In this paper, a novel relay selection method is developed for lifetime extension in an Amplify-and-Forward (AF) cooperative network where the transmission power is subject to a signal-to-noise ratio (SNR) requirement at the destination. In the proposed method firstly the average transmission power for every relay to forward the message is derived through the knowledge of channel statistics and then a utility function is designed to introduce it into the relay selection procedure so as to offer a relay more opportunity to be selected when its required transmission power is lower than usual. Simulation results show that the proposed method achieves improved performance in extending the lifetime by both reducing the average transmission power and lowering the residual battery energy.