Research On Device-to-Device Communication Based On NOMA

As one of the key technologies of 5G,D2D communication has been widely used due to its advantages such as low power consumption,low delay,and high spectrum utilization,alleviating the increasingly scarce spectrum resources.The two users are closer to each other to establish a D2D direct communication link under the control of the base station,which reduces the load of the base station and reduces the signal loss.In addition,users at the edge of the cell have improved the system throughput and expanded the system coverage by establishing a D2D communication link.In the D2D communication scenario of the cellular network,it is not a certain value for the distance of the D2D pair.In order to solve the problem that a direct communication link can't be established by the D2D users,a cooperative transmission CRNG scheme is proposed in this thesis.The cellular user is used as the information relay of the D2D pair to decode and forward the signal of the D2D users in the scheme,the throughput of the D2D pair is improved based on ensuring the communication quality of the relay cellular user.The simulation results show that the data rate of D2D users and the access rate of D2D pairs can be improved in the CRNG transmission scheme,and the service performance of cellular systems is also enhanced.In the D2D communication scenario of one-to-many resource multiplexing mode,multiple D2D pairs sharing the spectrum resource block of a cellular user improves the spectrum utilization ratio,but the interference between the cellular user and the D2D user is also more serious.In order to solve the problem of excessive interference between D2D users and cellular users,a resource allocation scheme based on NOMA grouping is proposed.D2D pair is grouped according to the distance between D2D users.D2D users in the same group share the spectrum resource block of the same cellular user and send signals to the receiver in the form of NOMA.This solution reduces the cumulative interference between D2D users.Simulation results show that the proposed resource allocation scheme improves the spectrum utilization rate,reduces the co-frequency interference caused by D2D users to cellular users,and improves the throughput of cellular users.