Study On Interference Suppression Techniques For UFMC System

Universal Filtered Multi-Carrier is a new multi-carrier modulation technology based on filter group filtering and the key technology of the fifth generation mobile communication system.It has high spectral efficiency and supports asynchronous transmission,thus it becomes the candidate waveform of the fifth wireless communication standard.When the signal is transmitted in the wireless channel,the signal will be attenuated because of the channel delay and the Doppler frequency shift that the performance of transmission and the information rate of the Universal Filtered Multi-Carrier system can be reduced.Thus the interference caused by the channel is the main issune in the development of Universal Filtered Multi-Carrier technology.This thesis focuses on how to reduce the influence of the multipath fading channel and Doppler frequency shift for the Universal Filtered Multi-Carrie system,so as to suppress the interference and improve the performance of the Universal Filtered Multi-Carrier system.In this thesis,we ficus on the interference cancellation of Universal Filtered Multi-Carrier system.New solutions and algorithms are proposed based on the study of the existing channel estimation and adaptive equalization algorithm for the Universal Filtered Multi-Carrier system.Firstly,aiming at the disadvantages of the complexity of the traditional channel estimation algorithm and the inaccurate of channel estination,this thesis is based on the analysis of the maximum likelihood channel estimation algorithm,and a method is proposed that the projection matrix is formed to determine the channel information.Then,the estimated result is taken as the initial value and the final channel information is obtained by iterative method.This iterative procedure is repeated until convergence and finally the signal response is determined by the channel information.It can be seen from the simulation results that this algorithm can effectively eliminate the interference in the Universal Filtered Multi-Carrier system and the performance of the Universal Filtered Multi-Carrier system is improved.Besides,in order to eliminate the inter-carrier interference and inter-symbol interference of UFMC system in the multipath fading channel,the theoretical analysis and discussion of the improved minimum mean square algorithm is proposed in this thesis.According to the correlation value of error signal,the algorithm is builded an improved step-size function relation based on the regulation of factor and the accumulation of correlation values of all error signal.Due to the multiple iterations and the update of the weight vector,the signal has the least error in the receiver.Thus the interference can be eliminated by the multipath channel in the receiver.The results show that the proposed algorithm has fast convergence speed and low steady-state error,and the Universal Filtered Multi-Carrier system has better performance of bit error rate.