The Research Of Signal Detection Algorithm In Massive MIMO System

Massive MIMO technology,as one of the key technologies of 5G communication,further improves the energy and spectrum efficiency of a communication system by the large increase in the number of antennas.However,the dramatic increase in the number of antennas also leads to complex signal detection at the receiving end in massive MIMO system,which has seriously affected the practical application of massive MIMO technology.In this context,this thesis studies the uplink signal detection in massive MIMO system to explore the signal detection algorithm suitable for practical applications.The main work of this thesis includes the following contents:Firstly,this thesis introduces the traditional linear signal detection algorithms(MF,ZF,MMSE)and nonlinear signal detection algorithms(MF-OSIC,MMSE-OSIC),and compares and analyzes the difference between each algorithm in traditional MIMO system and massive MIMO system through simulation.In the massive MIMO system with the number of antennas at the receiving end is much larger than the number of antennas at the transmitting end,an improved algorithm for linear signal detection is proposed by using MF algorithm which has better detection performance at low signal to noise ratio(SNR).while in the massive MIMO system with the same number of antennas at the receiving and transmitting end,an improved algorithm for nonlinear signal detection is proposed by using MF-OSIC algorithm which has better performance at low SNR.The simulation results indicate that the two improved algorithms can reduce the computational complexity while ensuring optimal detection performance.Secondly,this thesis introduces the principle of PIC detection,and proposes an MF-PIC algorithm,which uses the output of the MF algorithm as the input of PIC detection.The simulation results indicate that the proposed algorithm has better detection performance and lower complexity in massive MIMO system which the number of antennas at the receiving end is much larger than the number of antennas at the transmitting end.Aiming at the problem that the detection performance of the above algorithm is reduced when the number of antennas at the transceiver end is close,two improved algorithms are proposed,one is the MF-DPIC algorithm based on the second-level PIC,and the other is the MF-SPIC algorithm based on the MF-SIC.Finally,in the massive MIMO system which the number of transmit antennas and the signal-to-noise ratio have large variation,a single signal detection algorithm may have problems of poor detection performance or high complexity.Therefore,this thesis proposes an improved adaptive signal detection scheme with fixed number of receiving antennas.The signal detection algorithm is flexibly selected by the number of transmitting antennas and SNR.The simulation results show that the proposed scheme can not only achieve optimal detection performance but also has lower complexity than the best performance algorithm selected in the scheme.