Design Of F-OFDM Filter Module And Research On Improved PAPR Algorithm

With the rapid development of the communication industry,the existing Orthogonal Frequency Division Multiplexing(OFDM)technology is no longer suitable for future communication requirements due to the defects of fixed parameter configuration,high synchronization requirements,serious spectrum leakage and low spectrum utilization,so,new air interface technologies need to be explored.Filtered-OFDM(F-OFDM)technology not only has the advantages of OFDM technology,but also can set parameters dynamically and support asynchronous transmission.However,in order to reduce spectral out-of-band leakage,filters have been added in each subband,which will increase the implementation complexity of the system.At the same time,the F-OFDM system also has the problem that the Peak to Average Power Ratio(PAPR)is too high.Therefore,this paper mainly studies the filter module with low complexity,the F-OFDM system with high spectral efficiency,and the algorithm of weakening the PAPR of F-OFDM system.Firstly,the principles of the F-OFDM system are analyzed,including the basic principles of the F-OFDM system,the basic principles of the OFDM technology,and the PAPR of the FOFDM system.The simulation results show that compared with the OFDM system,F-OFDM system has the advantages of flexible parameter configuration and small out-of-band leakage.Secondly,the filter of the F-OFDM system is designed with a low-complexity window function method,the appropriate window function is selected by the simulation and analysis of different window functions,the baseband filter coefficients are generated and the filter coefficients of each sub-band are obtained by frequency shift.After comparing the time domain filtering and the frequency domain filtering in the filtering method,the frequency domain filtering operation is adopted to reduce the system complexity.Then,the resource grid design of the F-OFDM system is given,and the system is simulated and analyzed under different settings of the guard subcarriers.A scheme of setting guard subcarriers in the passband and transition band of the low-pass filter is proposed to improve the spectral efficiency,the simulation of the F-OFDM system from the three aspects of the position of the guard subcarriers,the width of the guard band,and the moving speed of the receiver proves the feasibility of the scheme.Finally,the PAPR performance improvement scheme of the F-OFDM system is studied,the common algorithms for weakening the system PAPR are studied,and the clipping algorithm,the selective mapping(SLM)algorithm and the companding transform algorithm are simulated and analyzed,which found that all three algorithms can effectively reduce system's PAPR.The multi-segment selection companding transform(MSCT)algorithm is proposed according to the companding transform algorithm,simulation results show that the MSCT algorithm can effectively reduce the system's PAPR,and at the same time,it can have a better system bit error rate performance.Based on the MSCT algorithm,a joint algorithm based on MSCT and SLM is proposed,and the simulation results show that the proposed joint algorithm can better attenuate the system PAPR,and at the same time,it can maintain good system bit error rate performance.