Power allocation in multi-hop OFDM transmission systems with amplify-and-forward relaying: A unified approach
In this paper, a unified approach for power allocation (PA) in multi-hop orthogonal frequency division multiplexing (OFDM) amplify-and-forward (AF) relaying systems is presented. In the proposed approach, we consider short and long term individual and total power constraints at the source and relays, and devise low complexity PA algorithms when wireless links are subject to channel path-loss and small-scale Rayleigh fading. To manage the complexity, in the proposed formulations, we adopt a two-stage iterative approach consisting of a power distribution phase among distinct subcarriers, and a power allocation phase among different relays. In particular, aiming at improving the instantaneous rate of multi-hop transmission systems with AF relaying, we develop (i) a near-optimal iterative PA algorithm based on the exact analysis of the received SNR at the destination; (ii) a low complexity suboptimal iterative PA algorithm based on an approximate expression of the received SNR at high-SNR regime; and (iii) a low complexity non-iterative PA scheme with limited performance loss. Simulation results show the superior performance of the proposed power allocation algorithms.
© 2016 Elsevier B.V. Received 8 October 2015, Revised 26 June 2016, Accepted 28 July 2016, Available online 30 August 2016. A. Azari would like to thank H. Khodakarami, R. Hemmati, A. Behnad, and R. Parseh for their helpful discussions on this work. The authors would also like to thank the anonymous reviewers for their thoughtful comments.
Submitted - 1508.01216.pdf