Opportunistic cooperation and optimal power allocation for wireless sensor networks

Cooperative communications is a promising technology to improve the performance of wireless sensor networks. In this paper, a dual-hop wireless cooperative network with opportunistic amplify-and-forward relaying is investigated over independent and non-identically distributed Nakagami-m fading channels. Due to the complicated form of the probability density function of the instantaneous signal-to-noise ratio (SNR), the symbol error rate and outage probability expressions are difficult to obtain in closed form. Taking advantage of Maclaurin series expansion of the probability density function of the output instantaneous SNR, we present the asymptotic symbol error rate and outage probability expressions at medium and high SNR regions, and the optimal power allocation scheme between the source and opportunistic relay is also proposed to minimize the outage probability. Simulation results demonstrate that the derived symbol error rate and outage probability matches well with the Monte-Carlo simulations. In addition, it is verified that the optimal power allocation scheme outperforms the equal power allocation scheme in terms of outage probability.