Design And Implementation Of Interference Cancellation Receiver In Uplink Non-orthogonal Multiple Access

In the past two years,the rapid development of wireless mobile services has put forward higher requirements for the fifth generation(5G)communication technology.5G network is supposed to support higher spectrum efficiency,larger system capacity and more application scenarios.The development of Non-Orthogonal Multiple Access(NOMA)technology provides a good technical support for 5G,but its system interference is still a major bottleneck restricting system performance.It is imperative to study the anti-interference receiving scheme with better performance and adapted to more scenarios.As key technologies of uplink receiver,multi-user detection and interference cancellation are of great significance for improving communication quality and system capacity.In this paper,we mainly discussed the design and performance of the uplink interference cancellation receiver based on the interference cancellation technique and NOMA system.The main work is as follows:Firstly,based on the requirements of larger transmission capacity and interference in actual environment,an uplink multi-cell and multi-user interference scenario is firstly proposed.In this interference scenario,there are both intra-cell interference and inter-cell interference.Accordingly,a receiver scheme combining MMSE-IRC and CW-IC(Code-Word Level SIC)is proposed based on the scenario.Through link level simulation on MATLAB,we discussed the different performance of 4 kinds of receiver schemes for multi-cell interference model,proved that the scheme we proposed can not only realize the inter-cell interference rejection and intra-cell cancellation,but can also bring better SINR gain compared to MMSE baseline receiver.Secondly,according to the verified scheme,the structure design of interference cancellation receiver is studied.we analyzed the structure and function of the existing MMSE-SIC receiver and found that on the one hand,the existing MMSE-SIC receiver could not meet the needs of multi-cell interference scenarios;on the other hand,it will cause error propagation in many parts of the detection process.So,a new iterative receiver structure in accordance with the receiver scheme was designed.We added MMSE-IRC into the iterative structure of CW-IC.By IRC interference rejection and Code-Word Level reconstruction of signal,we can further reduce the error propagation and improve the accuracy of signal detection.Finally,considering the gain performance of CW-IC receiver,Unequal SNR configuration for target user and interference user was proposed.We set up 2 intra-cell users model and 4 intra-cell users model,and conducted 4 test cases simulation work to compare the different performances between different SNR distribution scenarios.The results show that Unequal SNR distribution brings more obvious gain performance to the target user based on CW-IC receiver.