The Research On The Reduction Of Peak To Average Power Ratio In Filter Bank Multicarrier System

Filter Bank Multicarrier(FBMC)technology has less external interference and high frequency band utilization,which is considered as an effective method to overcome the existing problems in Orthogonal Frequency Division Multiplexing(OFDM)technology,and is also the key technology in the fifth generation mobile communication system.As a multicarrier system,FBMC system transmits signals which are composed of multiple subcarrier signals and has high peak power,so it faces the problem of peak to average power ratio.In this paper,the basic principle of FBMC system is analyzed,the generation and influence of peak to average power ratio are studied,and the algorithms with and without distortion are classified,then two algorithms to effectively suppress peak-to-average power ratio are proposed.Firstly,the precoding principle is analyzed,and the peak-to-average power ratio performance of the system is affected by introducing the precoding matrix at the sending end.The discrete fourier transform matrix and hadamard matrix are studied.On the basis of the existing ? Law companding algorithm,the discrete fourier transform matrix is introduced,and a joint algorithm based on Discrete Fourier Transform and ? Law(DFT-? Law)is proposed.In order to reduce peak to average power ratio better,Na and Choi are used to introduce multiple candidate signals,and a joint algorithm based on modified DFT-? Law(mDFT-? Law)is proposed.In this algorithm,the DFT is used to make the system use the single carrier effect more effectively by changing the phase-shift mode,and the signal form is changed to increase multiple candidate signals.Finally,the signal is companded.The simulation results show that the mDFT-? Law algorithm has better peak-to-average power ratio performance than the ? Law and DFT-? Law algorithm.Secondly,this paper studies the selective mapping algorithm,analyses the direct selection mapping algorithm was applied to FBMC system is not feasible.Then from the FBMC signal structure itself,put forward the Low Complexity Dispersive Selective Mapping(LDSLM)algorithm.This algorithm considers the overlapping characteristics of signals and analyzes the average power of signals.The analysis finds that the signal power is mainly concentrated in [nT+ T,nT+3T],so only the power concentration region is considered to shorten the search range and reduce the complexity of the system.Then,the algorithm of Clipping and Filtering(CAF)was further analyzed,and the LDSLM algorithm and CAF algorithm were combined to put forward the C-LDSLM algorithm.The joint algorithm adopted cascade mode,and the advantages and disadvantages of the two algorithms were weighed by adjusting the clipping rate reasonably.Through simulation verification,compared with LDSLM and CAF algorithm,this C-LDSLM algorithm can achieve more effective reduction of system peak to average power ratio on the basis of ensuring system bit error rate.