Joint Optimal Power Allocation and Relay Location for Amplify-and-Forward Multihop Relaying over Lognormal Channel

In this paper, a joint optimization of power allocation (PA) and relay location is proposed for Amplify-and-Forward (AF) multihop relaying over independent lognormal fading channels. The proposed optimization method maximizes the end-to-end (e2e) average signal-to- noise ratio (ASNR) having constraints on total transmit power with no per terminal maximum limit and assuming fixed e2e distance. Optimal parameters do not depend on instantaneous channel state information (ICSI) and can reduce complexity and power consumption. Optimal PA for maximizing e2e instantaneous SNR (ISNR) is also derived considering same constraints. Outage performance of joint optimization method based on ASNR and optimization method based on ISNR is compared. It is observed that joint optimization not only performs better than equal allocation, it can also outperform PA based on ISNR when link unbalance is large.