The Research On Mode Selection And Resource Allocation Algorithm For Device-to-Device Communication In 5G Cellular Network

As a result of the development communication technologies,the number of users and applications has increased exponentially,resulting in resource shortage and increased energy consumption.The data flow of the base station also increases with the growing number of users.In order to reduce the probability of failure of the cellular users in 5G,device to device(D2D)communication regarded as an important solution.This thesis studies mode selection and resource allocation points of D2 D communications and its impact on the key indicators of network performance.The study reveals the potential of opportuni stic communication beyond D2 D to improve energy efficiency,fairness an d cellular network capacity,when D2 D users can be formed and managed in cellular network.The introduction of D2 D links into a cellular network will bring many technical problems.such as D2 D device discovery and link establishment,mode selection,resource allocation and mobility management.In order to solve the coexistence problem between them,this thesis will focus on the issue of D2 D mod e selection and resource allocation underlying cellular networks.At present many studies of D2 D communication are based on traditional communication modes: cellular mode,D2 D shared mode,and D2 D dedicated mode.This thesis studies the new D2 D communicati on mode: Local route mode,direct D2 D mode a nd relay-assisted D2 D mode,classifying the load status of base stations in single cell,and corresponding communication modes are designed for different levels.Based on the whole network load of the base station in a single cell,this paper divides it in to two states: non full load and full load,and divides the non-full load into low load and medium load.The interference of D2 D users reusing uplink resources of cellular users under various load conditions is analyzed in detail.Firstly,is considered resource allocation and mode selection under low load.Because of more free resources in low load of BS,this thesis proposes a mode selection based on the maximum achievable rate and resource allocation scheme for low load.Secondly,is considered resource allocation and mode selection under medium load.In this section free resources are relatively less,than in the low load.Therefore,the primary mode selection based on channel state is proposed,and maximizing the throughput of D2 D users through joint mo de selection and resource allocation.Finally,is considered mode selection and resource allocation under full load.Due to no free resources under full load,so the non-full load option is no longer applicable.This thesis proposes a scheme for joint mode selection and resource allocation based on Kuhn-Munkres algorithm.Results of simulation show that the D2 D resource allocation and mode selection schemes offered in this paper for each level of load o f BS can greatly improve the spectrum utilization and transmission rate of D2 D users in terms of ensuring the fairness of D2 D users and cellular users.