Research On Radio Resource Allocation In Device-to-Device (D2D) System Underlaying LTE-advanced Networks

With the advent of the era of mobile Internet, people are constantly looking forward to morevariety of mobile data services with higher transmission rate. However, the contradiction betweenthe ever-increasing service requirement and the limited radio resource becomes more and moreprominent. The increasingly severe shortage of spectrum resource leads to the extensive researchabout how to exploit radio resource scientifically and rationally, which is significant in the nextgeneration mobile network. Device-to-Device technology arises in response to the proper time andconditions. The hybrid network, which is composed of the D2D system and the cellular system, notonly can improve resource utilization, but also can bring more diverse, more exciting and moreconvenient services.The D2D system underlaying LTE-Advanced cellular network is set as the research object inthis thesis, which focuses on the radio resource allocation in D2D system. Firstly, the thesis outlinesthe development of mobile communication technology and the related background knowledge,including the introduction about LTE-Advanced system and the theory of radio resource allocation.Then, the thesis researches the system architecture and some key technologies of D2Dcommunication, and analyzes the mutual interference by means of simulation.Two methods of radio resource allocation are proposed in this thesis: radio resource allocationbased on greedy algorithm and successive interference cancellation in D2D communication, andradio resource allocation based on genetic algorithm in relay assisted D2D communication. Theyboth consider a single cell interference scenario. The former applies to direct D2D communicationand aims to maximize the total throughput within a cell, which allows the coexistence of a cellularuser and multiple pairs of D2D users in a sub-bandwidth. Unlike the former, the latter is designedfor D2D communication with mobile relay, and the condition that maximize the success probabilityof resource allocation with the guarantee of reliable cellular communication. Simulation resultsshow that the two proposed methods can both obtain satisfied performance.Finally, the performance of proposed methods is optimized through power control, whichconcentrates on the power level of D2D system. Simulation results illustrate that the adjustment oftransmission power of D2D users to constrain the signal-to-interference-plus-noise ratio of D2Dcommunication in certain range, can achieve the goal of reducing energy consumption and the interference from D2D users to cellular users.