Precoding And Noise Mitigation Method Of MIMO NONA System Under Impulsive Noise Background

In recent years,with the rapid development of mobile communication technology,the demand for data transmission in human society has increased dramatically,and new business scenarios have continued to emerge.Intelligent modes of office,study and lifestyle make the current wireless communication system face huge challenges.In order to cope with the massive device connections and diversified application scenarios in the future communication system,the new multiple access technology has become a research hotspot in the communication field.Among them,as a potential new technology,non-orthogonal multiple access technology(NOMA)has attracted widespread concern from domestic and foreign scholars,on account of its advantages in significantly improving the spectrum efficiency,system capacity and energy efficiency of the system.In the meanwhile,the combination of NOMA and multipleinput multiple-output technology(MIMO)can further improve system performance.Therefore,taking the MIMO NOMA system as the research object,the paper studies the performance of the system from the perspective of system reliability and effectiveness.Under the background of impulsive noise,aiming at the MIMO NOMA system,this paper constructs system sum-rate maximization problem with the conditions of system transmission power limitation and users' rates constraints.Since the formed optimization problem is non-convex,it cannot be solved directly.In order to solve this problem,two schemes are proposed,using the difference of two convex functions(D.C.)algorithm and Fractional Programming(FP)algorithm to transform the optimization problem respectively.The D.C.algorithm uses the first-order Taylor expansion to approximately replace the objective function,and transform it into the D.C.form.And the FP algorithm uses a quadratic transformation method to decouple the numerator and denominator of the objective function in fractional form,and transform it into a specific form.Thus,both algorithms can obtain the optimal solution to the original problem.From the simulation results,it can be seen that the two proposed algorithms can dramatically improve the sum-rate performance of the MIMO NOMA system.Regarding to the impulsive noise in the communication scene,the impulsive noise mitigation algorithms in the time domain are mainly studied.Taking the output signalto-noise ratio and bit error rate performance of the system as the evaluation targets,an improved impulsive noise mitigation algorithm is proposed,which is based on the classic hybrid time-domain nonlinear preprocessing method.A detailed mathematical derivation of the calculation process of the index is carried out,and the proposed scheme is compared and analyzed with other schemes.At last,the simulation results show that the proposed improved impulsive noise mitigation algorithm can effectively improve the output signal-to-noise ratio and bit error rate performance of the system to a certain extent.This thesis contains 23 figures,5 tables and 80 references.