Seleção de relay em sistemas OFDM cooperativos com amplificadores de potência não lineares.

Abstract

In recent decades, techniques such as orthogonal frequency division multiplexing (OFDM) and, more recently, cooperative communications have been gained ground in the telecommunications area. However, with the adoption of such techniques, some challenges arise, such as reducing the power peaks of OFDM symbols or relay selection in cooperative systems. Based on this, the present work presents two new per-subcarrier relay selection techniques for cooperative OFDM communication systems with nonlinear power amplifiers (PAs) and considering the amplify-andforward (AF) protocol. The proposed techniques are based on a developed theoretical expression fortheinstantaneoussignal-to-noiseratio(SNR)ofanAFcooperativeOFDMsystemtakinginto account the nonlinear distortions introduced by the relays’ PAs. The 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.