Research On PAPR Suppression Technology For OFDM System

The modern wireless communication system,orthogonal frequency division multiplexing(OFDM)technology is widely used because of its high data transmission rate.In addition,OFDM technology is selected as IEEE 802.11a/g and IEEE 802.16 communication industry standard,and is also one of the alternative technologies of 5G mobile communication system.However,the peak to average power ratio(PAPR)problem of OFDM technology will make high power amplifier(HPA)work in the nonlinear region,and introduce nonlinear distortion to worsen the BER performance of the system.With the rapid development of wireless communication systems,it is urgent to solve the problem of high PAPR in OFDM signals.It is of great significance to study PAPR suppression technology.Therefore,the PAPR suppression technology is studied in this thesis.The main research results are as follows:1.Clipping technology can suppresses the PAPR and interferes.In order to solve the nonlinear distortion problem introduced by clipping and HPA,a nonlinear distortion recovery algorithm based on compression sensing(CS)is proposed.Firstly,to reducing the influence of clipping interference on the signal,a preprocessing method based on Taylor series expansion is proposed.Secondly,the iterative noise elimination algorithm is used to further eliminate the residual clipping interference;finally,the sparsity of clipping noise is used to consider the nonlinear distortion introduced by the clipping and HPA.Using CS recovery algorithm to recover the nonlinear distortion signal.Simulation results show that the proposed algorithm can effectively suppress PAPR and improve the BER performance of the system.2.Selective Mapping(SLM)algorithm can suppress PAPR without signal interference,but it can't effectively suppress PAPR while reducing the edge band information transmission.The thesis proposes an improved SLM algorithm.Firstly,We propose to use weighted logistic chaos sequence instead of IFFT matrix in SLM algorithm,to reducing the system sideband information transmission;secondly,to effectively suppress PAPR,the thesis proposes to increase the diversity of alternative signals in the time domain by rotating vector sequence.Simulation results show that the improved SLM algorithm not only reduces the system sideband information transmission,but also effectively suppresses the PAPR.