Research On The Algorithm Of Reducing PAPR In FBMC-OQAM System

The filter bank multi-carrier offset quadrature amplitude modulation（FBMC-OQAM）,has the advantages of high frequency spectral efficiency and low out of band radiation.However,as a multi-carrier communication system,FBMC-OQAM system has the problem of high peak-to-average power ratio（PAPR）.In this paper,how to reduce the PAPR of FBMC-OQAM system is studied.Based on the classical partial transfer sequence（PTS）algorithm,two improved algorithms are proposed for FBMC-OQAM system.In a multi-carrier system,the amplitude of each subcarrier in the frequency domain will affect the superimposed waveform in the time domain.Based on this characteristic,a weighted PTS（WPTS）algorithm based on the traditional PTS algorithm is proposed,which weights the amplitude of FBMC-OQAM signal in frequency domain.Because the subcarriers with high frequency are more prone to mutation and generate peak value signal,while the probability of generating peak value signal of low-frequency subcarriers is smaller,the WPTS algorithm proposed in this paper gives low weight value to high-frequency subcarriers and high weight value to low-frequency subcarriers in frequency domain,so as to further reduce the PAPR of signal.Compared with the PTS algorithm,the computational complexity of the WPTS algorithm is basically not increased.It is the same as O（MW^V）in magnitude.However,the simulation results show that the WPTS algorithm reduces the PAPR by nearly 0.5d B when the complementary cumulative distribution function（CCDF）is 10^-3.The FBMC-OQAM system adopts offset modulation,and the transmitted complex signal has the characteristics of interleaving real part and virtual part for half a period.Based on this structure,an improved multi-block-joint-optimization PTS（MPTS）algorithm:MPTS-T/2 algorithm with half cycle is proposed.In the MPTS-T/2 algorithm,the real part and the virtual part of a complex signal are regarded as two FBMC-OQAM signals.On the basis of the MPTS algorithm,the operation period is halved,that is to find the best phase factor vector in terms of the half cycle signal.MPTS-T/2 algorithm refines the granularity of finding the best phase factor vector,which can further enhance PAPR suppression effect in theory.The simulation results show that whenCCDF=10^-3,V=4,the PAPR reduction performance of the MPTS-Suc-T/2 algorithm is nearly 0.9db better than that of the MPTS-Suc algorithm,and is close to or even better than that of the MPTS-DP algorithm,while the computational complexity of MPTS-Suc-T/2 algorithm is only 12.5%of the computational complexity of MPTS-DP algorithm.