Research On Phase Noise And IQ Imbalance Compensation Technology In GFDM System

Generalized Frequency Division Multiplexing(GFDM)technology is a new non orthogonal multi carrier modulation technology.Compared with Orthogonal Frequency Division Multiple(OFDM)technology,it has more flexible time-frequency structure,lower out of band radiation,smaller peak to average power ratio and higher spectral efficiency,and has broad application prospects.Considering that the wireless terminal in the future mobile communication application scenario needs to be miniaturized and intelligent,a receiver with compact structure,low power consumption and low cost is essential.However,high integration will inevitably cause various RF damage.Therefore,it is of great significance to study the estimation and compensation technology of receiver phase noise and In-phase and Quadrature-phase(IQ)imbalance.This thesis focuses on the estimation and compensation algorithm of phase noise and IQ imbalance in GFDM transmission system.The main research work of this thesis is as follows:(1)Aiming at the problem of channel and phase noise estimation of GFDM system under time-varying channel conditions,using the GFDM frame structure composed of block pilot symbols and discrete pilot symbols,a joint iterative channel,phase noise estimation and symbol detection algorithm based on Kalman filter is proposed.The channel state information of GFDM block pilot symbols is obtained by using the joint channel and phase noise estimation algorithm based on least square iteration,and the Kalman filtering algorithm is introduced for channel tracking.Firstly,based on the channel state information and covariance matrix predicted by Kalman filtering algorithm,phase noise estimation and data symbol detection are carried out,and the observation matrix in Kalman filtering algorithm is updated;Secondly,the Kalman filtering algorithm is used to correct the channel state information,and the phase noise estimation and data symbol detection are carried out again,and the observation matrix is updated to realize the iterative processing of channel estimation,phase noise estimation and symbol detection.The proposed algorithm can track the channel effectively,compensate the phase noise in the system effectively,and improve the bit error rate performance of the system.(2)Aiming at the problem of phase noise and IQ imbalance in GFDM system under time-varying channel conditions,a joint iterative channel,phase noise and IQ imbalance estimation and GFDM symbol detection algorithm based on Kalman filter is proposed.In the block pilot symbol,in order to avoid the influence of phase ambiguity on the estimated value of IQ imbalance parameters,the estimated quantity is converted and expressed in the form of the sum of estimated value and estimated error.The estimated error and estimated value are continuously updated through iteration,and finally the estimated value of IQ imbalance parameters and channel state information of GFDM block pilot symbol are obtained.After IQ imbalance compensation for GFDM discrete pilot symbols,Kalman filtering algorithm is used to track the channel,estimate phase noise and detect symbols.The proposed algorithm can ensure the bit error rate performance of GFDM system in poor IQ imbalance environment.