The Research Of PAPR Reduction Scheme In UFMC Systems

In recent years,more and more new business appear with the rapid development of mobile Internet and Internet of Things technologies.Existing data services show an explosive growth trend because of the large number of new demands.And 5G era will come soon.Due to the changes in demand and application scenarios,new generation mobile communication systems requires bigger challenges in transmission rate,system efficiency and resource utilization.Multi-carrier systems,especially Orthogonal Frequency Division Multiplexing(OFDM),have been widely used in current 4G communication systems.OFDM systems cannot meet these new requirements of 5G systems due to the inherent defects of their systems.As a new type of multi-carrier technology,Universal Filtered Multi Carrier(UFMC)is considered to be an effective way to meet 5G requirements.The UFMC system uses sub-band-based filtering processing,which has better out-of-band rejection,better performance in terms of carrier frequency offset(CFO)interference and spectral efficiency than OFDM systems.But the UFMC system also faces the problem of Peak to Average Power Ratio(PAPR).Excessive PAPR value will increase communication system design difficulty and implementation complexity.Therefore,it is necessary to suppress the PAPR value in the UFMC system.This thesis mainly studies the SLM method in the PAPR suppression.Then two PAPR suppression algorithms are proposed in thesis.Firstly, IGASLM algorithm which applies the SLM method to the UFMC system is proposed.The frequency domain signal experiences phase rotation before IFFT transform at the transmitting end.And the optimal set of phase rotation sequences is selected by the genetic algorithm.The genetic algorithm has the local optimal problem,so multi-point crossover and adaptive parameter techniques are used.And this algorithm is called IGASLM algorithm.The MATLAB simulation analysis proves that the IGASLM algorithm can effectively suppress the UFMC system.PAPR value.Then an algorithm that can get the optimal phase rotation sequence quickly is proposed according to the characteristics of SLM method structure.This algorithm uses the correlation theorems such as Chernoff bound,stochastic process,Ehlich and Zeller theorem to perform mathematical analysis on it.The algorithm of calculating phase rotation sequence is got by step-by-step analysis.Firstly,this algorithm obtains the first phase rotation factor randomly.Then,the optimal next phase rotation factor is calculated in turn and finally the optimal phase rotation sequence is obtained.At the same time,time-frequency conversion of the transmitter signal is done according to the characteristics of UFMC system and SLM method.Therefore the proposed algorithm can be applied to the UFMC system.The simulation results show that the proposed algorithm can quickly calculate the phase rotation sequence of the SLM method and has great performance in PAPR.Finally,the research work of the full text is summarized and the future research work is prospected at the end of the thesis.