Research On Interference Cancellation Technology Of LTE Uplink System

In order to enhance the competitiveness of the third generation mobile communication technology in the field of wireless access,the Long Term Evolution(LTE)is proposed by 3GPP.The purpose of LTE is to reduce system delay,improve data rate,expand the system coverage and increase the system capacity,while reducing operating costs.At present,the major communication equipment companies are actively studying LTE,thus the research of LTE technology is of great significance.Interference is one of the main factors that limit the performance of LTE.This thesis mainly studies the interference cancellation technology of the physical layer link of LTE uplink system.The main work of this thesis is as follows:According to the structure of LTE,the simulation platform is built.The platform includes some main elements of the LTE link layer,including MIMO,channel coding,OFDM,DFT mapping,etc..On the platform,the traditional interference cancellation algorithm is realized and verified by the simulation,including ZF algorithm and MMSE algorithm.In view of the random distribution of user location in LTE,this thesis focuses on the situation that the distance of two mutually interfering users is unequal.The results show that the difference of users'distance or power will decrease the performance of the traditional algorithm.In view of this situation,this thesis uses soft information to reconstruct the interference,and counteract interference with the iterative method.This method is called reconstruction algorithm,and it is simulated on the simulation platform.The simulation results show that the interference reconstruction algorithm can significantly improve the efficiency and reliability of the system in the case of large signal to noise ratio.Due to the complexity of the interference reconstruction algorithm is high,this thesis further considerate to reconstruct the interference with the hard decision.This method is called decision reconstruction algorithm,and it is simulated on the simulation platform.proposes a new improved algorithm,that is the decision reconstruction algorithm,and the performance of the algorithm is simulated and analyzed.The simulation results show that the improved algorithm not only can improve the efficiency and reliability of the system in the case of large signal to noise ratio,but also can be simple and easy to achieve.In addition,in terms of the degree of improvement,the decision reconstruction algorithm is much better than the interference reconstruction algorithm.