Relay Selection Methods for Cooperative OFDM Systems with Nonlinear Power Amplifiers

This paper presents two new per-subcarrier relay selection techniques for cooperative orthogonal frequency division multiplexing (OFDM) communication systems with nonlinear power amplifiers (PAs) and considering the amplify-and-forward (AF) protocol. The proposed techniques are based on a developed theoretical expression for the instantaneous signal-to-noise ratio (SNR) of an AF cooperative OFDM system taking into account the nonlinear distortions introduced by the relays’ PAs. Our results show that both the proposed techniques can significantly improve the system capacity when compared to a classical relay selection method. Numerical simulation results are presented to validate the performance of the proposed techniques.