Power Allocation for Amplify-and-Forward Relaying with Correlated Shadowing

Power allocation is a key technique to exploit the benefits of cooperative relaying. In this paper, we investigate the effect of shadowing on the power allocation of amplify-and-forward cooperative relaying systems. Considering the joint effects of path loss, correlated shadowing and flat Rayleigh fading, the approximate outage probability at high signal-to-noise ratio (SNR) is first derived. Then we solve the power allocation problem by minimizing the approximate outage probability subject to a total power constraint. It is shown by the analytical results that the correlation coefficients and the standard deviations of shadowing have significant impacts on the power allocation. The simulation results show that the proposed power allocation scheme yields about 2 dB SNR gain compared to the equal power allocation in the high SNR regime.