A Genetic-Simulated Annealing Algorithm Based on PTS Technique for PAPR Reduction in OFDM System

In this paper, we propose a genetic-simulated annealing algorithm (GSAA) with partial transmit sequence (PTS) technique (GSAA-PTS) to reduce the peak-to-average power ratio (PAPR) for orthogonal frequency division multiplexing (OFDM) system. Genetic algorithm based PTS method (GA-PTS) is a novel and suboptimal PAPR reduction approach, which has lower computational load than original PTS method. However, researchers still focus on how to improve the PAPR performance. The proposed method GSAA-PTS takes the advantages of genetic algorithm and simulated annealing algorithm to search the best phase factors of PTS. In this method, we initialize the population firstly, and then selection, crossover and mutation are used to generate the new population, finally using the simulated annealing algorithm to update each chromosome in the population. The simulation results show that the better performance of PAPR have been achieved by adopting GSAA-PTS scheme.

I. Introduction

Orthogonal Frequency Division Multiplexing (OFDM) is a unique multi-carrier modulation technique. In recent years, it has been used extensively in communication systems and radar systems. Due to its high spectrum efficiency and channel robust, it is becoming more and more popular in commercial and academic research. But OFDM signals still remain some limitations, one of the main drawbacks is high Peak-to-Average Power Ratio (PAPR) of time-domain signals. OFDM signals are composed of many individual sub-carriers, when the phases of output sub-carriers are identical, the peak power of the transmitted signal will be higher than the average power. High PAPR raises a higher requirement to linearity of transmit power amplifier, but many amplifiers are nonlinear and have the finite dynamic range, when the OFDM signal transmitted by a nonlinear power amplifier, it may suffers from spectral spreading and in-band distortion. While, the increase of dynamic range in a transmit power amplifier will lead to lower efficiency and higher costs. So we must try to reduce the PAPR in OFDM system.