Research Of Improved PTS Algorithm With PAPR Reduction For OFDM System

Orthogonal Frequency Division Multiplexing(OFDM)is a multi-carrier transmission with strong anti-fading,efficient spectrum utilization and data transfer rates.It is considered to be one of the core technologies of 4G mobile communication system.However,OFDM system can easily result in high Peak to Average Power Radio(PAPR).If signal with high PAPR are trapped into the nonlinear region of power amplifier,it may cause signal distortion and destroy the orthogonality of OFDM signals.Therefore,research of PAPR reduction algorithm for OFDM system is crucial.First,this thesis introduces the basic principles of OFDM technology as well as its merits and drawbacks,And the PAPR reduction algorithms,including limiting width algorithm,coding algorithm and the algorithm of reducing the probability of high PAPR.Then the inhibiting properties of these traditional PAPR reduction algorithms are analyzed and compared.The partial transmit sequences(PTS)algorithm is selected to research,which has better performances of reducing PAPR,and its two disadvantages are improved.Second,in order to improve the disadvantage of high complexity in PTS algorithm,two intelligent optimization algorithms,genetic algorithms and particle swarm optimization algorithm are adopted in searching optimal phase factors of PTS algorithm to reduce the PAPR.After the research of genetic algorithm and its applying in PTS,two new algorithms called multi-population genetic PTS algorithm and particle swarm optimization PTS algorithm are proposed.The simulation experiments show that the PAPR properties of these three improved PTS algorithm are second only to the traditional PTS algorithm,but their computational complexity reduction ratio are as high as 98%,94%,97%,Among them,the particle swarm optimization PTS algorithm achieves the best performance with the expense in PAPR to significantly reduce the computational complexity of system.Finally,in traditional PTS algorithm,the detection and recovery of original signals at the receiver need side information,which will result in system redundancy.Based on the improved PTS algorithm with intelligent algorithm,a without side information PTS algorithm is proposed by estimating the phase factors according to the guidelines.And on this basis,a without side information PTS algorithm with an expansion phase factor is proposed.The simulation experiments show that,the bit error rate of signals with the without side information PTS algorithm is approximately equal to that of the traditional PTS algorithm.The improved PTS algorithm does not need to transmit side information,so it reduces the redundancy of the system,and improves the performance of the system effectively.