| Multicarrier modulation technology is widely used in communication systems.OFDM,as the key technology in 4G,has made a deep impression on its excellent performance.With the progress of the times,4G can not meet the growing demand of people.People have a strong desire for the early arrival of 5G.Filtered-OFDM(F-OFDM)is a candidate solution for the fifth generation mobile communication system(5G).Its basic idea is to divide the spectrum resources into a number of different subbands.Each subband can configure different parameters according to different business scenarios and design the corresponding subband filters according to the different subband parameters.Then the band filter is used to suppress the leakage of the external spectrum,so as to improve the spectrum utilization.As a technology based on multicarrier modulation,it also has the shortcoming of high peak to average power ratio(PAPR).High PAPR improves the requirement of system power amplifier,so it is particularly important to reduce PAPR in the actual production environment.As a simple,low complexity and effective method to suppress high PAPR,signal pre distortion technology has been widely studied.This paper mainly studies the application of the compression expansion algorithm in the signal pre distortion technology in Filtered-OFDM,analyzes the performance of the suppression of PAPR and the effect on the bit error rate of the system.This thesis first analyzes the basic principles of Filtered-OFDM,and focuses on the design of subband resource grid,subcarrier mapping and subband filter.Simulation analysis of Hanning,Hamming and Kaiser three kinds of window function filters,QPSK,16 QAM,64QAM three modulation mode F-OFDM BER performance.On this basis,the peak to average power ratio(PAPR)of the Filtered-OFDM system is simulated and analyzed,and the different sub band configuration and the peak to average ratio under different modulation orders are discussed.This paper studies the method to reduce the peak to average power ratio of F-OFDM systems,and focuses on the relatively mature compression expansion algorithm that restraining high PAPR in OFDM system.The performance of the F-OFDM system in the literature [26] and literature [27] is also analyzed.Finally,the two sub-band Filtered-OFDM systems are built with LabView/Matlab and USRP,and the BER of the system is analyzed.The algorithm is verified by comparing the situation of PAPR suppression and the BER of different compression expansion algorithms in USRP environment and simulation environment. |
