Research On Power Control And Resource Allocation In D2D Communication

Device-to-Device(D2D)communication becomes its short distance direct communication can get advantages such as reduce latency and it has become one of the key technologies of 5G in the future.However,when a large number of D2 D users communicate by sharing resources with cellular users,severe interference will occur between users which uses the same frequency band.Therefore,when a dense D2 D user is introduced into a cellular network,the interference coordination is an important issue worth studying.In addition,it is also one of the current research hotspots for D2 D technology to introduce idle cellular users as relays to assist communication in environments with poor communication quality.In this thesis,cellular and D2 D hybrid networks are taken as the research objects.The problem of interference coordination of D2 D communication under high-density scenes and with relay assistance is mainly studied.The main work of this thesis includes:Aiming at the severe co-channel interference caused by D2 D communication in high-density scenes,this thesis presents a resource allocation scheme based on grouping and a power control based on adaptive particle swarm optimization.These measures can improve the system throughput and the D2 D users' access volume effectively.In terms of resource allocation,the packet center is selected by the distance,and each D2 D packet is determined by the interference value.Finally,the multiplexing cellular user resources for each packet are determined by the principle of maximum signal to interference and noise ratio.In terms of power control,an adaptive particle swarm algorithm is proposed to ensure the service quality of cellular users and D2 D users while reducing the interference between users of each link.The simulation results show that the proposed algorithm can ensure that more than 93% of D2 D users access the cellular network,and the spectral efficiency of the system is more than doubled that of the comparison random algorithm.Aiming at the interference caused by introducing relay technology into D2 D communication,this thesis proposes a D2 D interference coordination scheme for joint relay selection,power control and resource allocation.Firstly,by analyzing the objective function of the system,it is equivalent to a two-stage optimization problem of power control,relay selection and resource allocation.In the power control problem,the original subproblem is transformed into a linear fractional programming problem.The optimal transmit power is obtained by the Dinkelbach algorithm.It is transformed into the best matching problem in graph theory on the issue of relay selection and resource allocation.The optimal matching is obtained by using the KM algorithm.The simulation results show that when the maximum distance between D2 Ds is 70 m,the relay assistance algorithm proposed in this thesis improves the throughput by 31% compared with the non-relay algorithm.