Power minimization for OFDM Transmission with Subcarrier-pair based Opportunistic DF Relaying

TL;DR

This paper proposes a resource allocation algorithm for OFDM systems with opportunistic decode-and-forward relaying, achieving power minimization under a sum-rate constraint through optimization techniques.

Contribution

It introduces an optimized subcarrier pairing and power allocation method using dual and Hungarian algorithms for improved power efficiency in OFDM relaying.

Findings

Significant power reduction with optimized subcarrier pairing.

Efficient polynomial-time algorithm for resource allocation.

Validation through numerical results demonstrating power savings.

Abstract

This paper develops a sum-power minimized resource allocation (RA) algorithm subject to a sum-rate constraint for cooperative orthogonal frequency division modulation (OFDM) transmission with subcarrier-pair based opportunistic decode-and-forward (DF) relaying. The improved DF protocol first proposed in [1] is used with optimized subcarrier pairing. Instrumental to the RA algorithm design is appropriate definition of variables to represent source/relay power allocation, subcarrier pairing and transmission-mode selection elegantly, so that after continuous relaxation, the dual method and the Hungarian algorithm can be used to find an (at least approximately) optimum RA with polynomial complexity. Moreover, the bisection method is used to speed up the search of the optimum Lagrange multiplier for the dual method. Numerical results are shown to illustrate the power-reduction benefit of the improved DF protocol with optimized subcarrier pairing.