Research On D2D Communication Based On NOMA And IRS

With the continuous development of communication technology,human-computer interaction and the Internet of Everything have become the themes of the new era.How to provide technical means with low latency,low power consumption and high frequency band utilization in limited spectrum resources has become the unremitting efforts of communication researchers.Device-to-Device(D2D)is used in cellular networks,which can effectively reduce the traffic load on the base station side and improve network capacity and spectrum utilization;At the same time,Non-orthogonal Multiple Access(NOMA)not only improves the spectrum utilization,but also takes into account the fairness of users and reduces the interference between users,which has attracted the attention of many scholars;Intelligent Reflecting Surface(IRS)has aroused extensive discussion as soon as it appeared.It is known as a promising 6G technology due to its low cost,easy deployment,quasi-passive,and programmable characteristics.In this paper,the above three technologies are combined to study the performance of the uplink communication system,and propose a mobile relay selection method based on capacity and social relations.The details are as follows:Aiming at the capacity problem of two-hop D2 D communication in cellular systems,a communication model using NOMA to assist two-hop D2 D mobile relay is proposed.First,according to the probability density function(PDF)and cumulative distribution function(CDF)of each signal,the closed expression of the ergodic total capacity under the Rayleigh fading channel model is obtained.The total traversal capacity of NOMA’s two-hop D2 D communication,in addition,a capacity-based social relationship mobile relay selection(CSRS)method is proposed.The simulation results verify the correctness of the theoretical derivation.Compared with the scheme without NOMA,using NOMA The proposed two-hop D2 D communication scheme greatly improves the system capacity,and the proposed relay selection method can also make the system obtain better performance.Aiming at the upstream communication capacity of D2 D communication under NOMA network,a communication model using IRS to assist NOMA and D2 D is further proposed.The ergodic capacity of each signal of the system under Nakagami-m fading channel is deduced.Monte Carlo simulation is used to verify the correctness of the theoretical deduction.The number of different IRS elements and the system capacity without IRS are compared.The number of components is positively correlated with the system capacity.The system performance is better when the IRS is located close to the transmitter or receiver.Compared with the DF relay,the IRS can further improve the communication capacity of the system.