Uma Abordagem Heurística para o Algoritmo PTS na Redução da PAPR em Sistemas OFDM

Abstract

This paper deals with peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems under the perspective of heuristic optimization applied to the partial transmit sequence topology, seeking the reduction of computational complexity. We have analyzed and evaluated the partial transmit sequence (PTS) technique for reducing PAPR levels by means of heuristic optimization, namely particle swarm optimization (PSO). An elevated PAPR level on an OFDM signal implies an energy efficiency reduction of the high-power amplifiers (HPA) at the transmitter electronics, whose operating point must be moved in order to keep the output signal free from distortion; this is achieved by reducing the input signal power by a level known as input back-off (IBO). Numerical results have been compared with the conventional PTS (C-PTS) algorithm, especially regarding the trade-off between computational complexity versus PAPR reduction. Our numerical results have demonstrated that by using the PSO-PTS algorithm it is possible to achieve near optimal results in approximately a quarter of the time used by C-PTS, making the former more suitable for commercial applications that involve a large number of subcarriers, which implies in a high-PAPR OFDM signal.