Interference Cancellation Algorithm In The Mutiuser Non-Orthogonal Shared Access System Of 5G

With the development of mobile communication, 4G is commercially available on a large scale, the research of 5G is in full swing. With the arrival of the era of the Internet of things, 5G communication system will face massive connections scenario, and there is an urgent need to further enhance the system capacity. The existing orthogonal multiple access technology cannot meet the demand of 5G, so nonorthogonal multiple access technology with the good performance of channel capacity makes the advantages of non-orthogonal multiple access technology become a hot candidate in 5G.Firstly, this paper introduces the four kinds of popular multiuser non-orthogonal access systems and multi-user detection technology. Non-orthogonal system introduces non-orthogonal at the transmitter, and there will be multiple access interference between the users because the user data is not orthogonal to each other. The receiver will take advantage of complex multi-user detection techniques to separate the user data. Linear detection technology is difficult to meet the demand of system performance, so the receiver adopts linear detection module and simple serial interference cancellation receiver.Thereafter, the paper studies the non-orthogonal downlink multi-user shared access model. On the basis of downward two non-orthogonal user model, the analysis of the downlink AWGN channel capacity demonstrates the superiority of nonorthogonal access way. The paper studies the downlink interference cancellation scheme, and simulation results are given to verify the BER performance. And further the improved the non-orthogonal system is put forward, the introduction of extended sequence at the transmitter enhance the BER performance of the system.Finally, this paper studies the uplink multi-user non-orthogonal access model. The analysis of AWGN channel uplink channel capacity proved that the uplink channel capacity of non-orthogonal multi-access is superior to orthogonal multiple access. Respectively analyzed using different spreading sequences sending at the transmitter, simulation results show that the complex multivariate sequence gives better performance. And conduct the thorough research to the uplink interference cancellation process. MMSE-SIC algorithm is analyzed in detail. and aiming at the problem of large time delay of the MMSE-SIC algorithm, quasi parallel interference cancellation algorithm is proposed, but the overload performance fell. Then on the basis of this puts forward improving interference cancellation schemes, the improved interference cancellation algorithm is proposed. Ensuring the performance of the overload situation, it reduces system latency under high load scenarios.