Research On Algorithm Of Reducing In FBMC-OQAM System

As an important technology for signal modulation in future communications,the filter bank multi-carrier-offset quadrature amplitude modulation(FBMC-OQAM)has gradually attracted people's attention.However,multi-carrier transmission systems are difficult to avoid the problem of high peak-to-average ratio(PAPR).Therefore,it has become a research hotspot that how to effectively suppress the PAPR.Due to the structural difference between the FBMC-OQAM system and the orthogonal frequency division multiplexing system(OFDM),the traditional PAPR suppression schemes of OFDM system are not applicable to FBMC-OQAM systems,the existing suppression methods are not yet mature and still have some shortcomings.Aiming at above problems,this thesis mainly researches the PAPR suppression algorithm in FBMC-OQAM system.The specific contents are as follows:Aiming at the problem that the traditional PTS algorithm is too complicated and does not apply to the FBMC-OQAM system,an improved iterative partial transmission sequence algorithm applied in FBMC-OQAM system is proposed.The proposed algorithm improves the search method based on the traditional iterative partial transmission sequence(IPTS)method.The phase factor vector is iteratively searched according to two types of parity,which expands the search scope.Then contact the FBMC-OQAM system characteristics,taking into account the overlap between data blocks during optimization,selecting the phase factor vector with the smallest PAPR of the sum of the candidate transmission sequence in the current data block and the overlapped optimal transmission sequence as the optimal phase factor vector,The two-layer idea is introduced lastly,the signal is optimized two times every time,and the suppression effect is strengthened,so that the PAPR of the system can be effectively suppressed without increasing the amount of calculation.Through theoretical analysis and simulation,it is verified that compared with the IPTS algorithm,the proposed scheme adds a little amount of computation in exchange for better PAPR performance.At the same time,the improved algorithm is superior to the traditional partial transmission sequence(PTS)algorithm in terms of PAPR performance and computational complexity.Aiming at the problem that the traditional TR algorithm does not apply to the FBMC-OQAM system,an improved adaptive tone reservation algorithm applied in FBMC-OQAM system is proposed.The improved algorithm combines the overlapping features of the system based on the traditional tone reservation(TR)algorithm,divides signals into overlapping sectors and introduces an adaptive threshold factor so that when the threshold is not set to the optimal point,it can still be adjusted adaptively.At the same time,an adaptive scaling factor is introduced for each data segement and a signal that the waveform is similar to the clipping noise is generated as a peak cancellation signal,optimize each segment in turn.The improved algorithm can effectively suppress the system's PAPR on the basis of adding a small amount of calculation,and enter the convergence state with less iteration.Through theoretical analysis and simulation,it is verified that the complexity of the proposed scheme has better computational complextity and PAPR suppression performance and better overall.