Research On Coexistence Of FMT And FBMC/OQAM In Multi-service Scenario

The physical layer of the future network will provide modulated waveforms with multiple carrier intervals and carrier number configurations,and allow different services to use different waveforms for non-orthogonal access.A feasible solution is to divide the system bandwidth into several service subbands,and each service subband is used for different types of services.In this multi-type service system,each service has its best frame structure,and different service data uses different filters to complete the shaping process.Filtered Multitone Modulation(FMT)and Filter Bank Multicarrier/Offset Quadrature Amplitude Modulation(FBMC/OQAM)can be well applied to the future complex communication scenarios due to good spectrum convergence characteristics.This thesis focuses on the following two issues for the coexistence of FMT and FBMC/OQAM waveforms during non-orthogonal access:1.Aiming at the interference of adjacent frequency bands for the coexistence system of FMT and FBMC/OQAM,this thesis proposes a scheme for numerical analysis using fast convolution method.The fast convolution method generates FMT and FBMC/OQAM signals simultaneously in adjacent frequency bands,and the guard interval is adjusted with the granularity of fast Fourier transform.Finally,a numerical model of subcarrier interference based on the fast convolution scheme is obtained.Simulation results show that the interference of coexistence system will seriously affect the system transmission performance.Compared with the existing Power Spectral Density(PSD)interference analysis scheme,fast convolution is more accurate for system interference analysis and has more practical value for evaluating interference values between waveforms.2.For the interference problem of adjacent frequency bands in coexistence system of FMT and FBMC/OQAM,this thesis proposes an interference repression scheme by optimizing filter transition band coefficients.Based on the subcarrier interference numerical model,the change value of FMT spectrum frequency can be obtained.In this thesis,the interference matrix of FBMC/OQAM to FMT system is constructed,and the MMSE precoding scheme is proposed to adjust the filter transition band coefficient to complete the signal reconstruction.Simulation results show that minimum mean square error precoding can effectively inhibit the interference between FMT and FBMC/OQAM in adjacent frequency bands.Compared with the scheme of setting sufficient guard intervals,the proposed precoding scheme improves the utilization of spectrum resources.