Research On Relay Technology Based On Device To Device In Cellular Network

With the popularity of mobile smart terminals,the media for access to information is becoming more diverse,including pictures,audio,video,etc.,which lead to explosive growth in the amount of data in the mobile network,and then inspired the development of mobile communication technology.Now,LTE has been on a wide range of commercial worldwide,LTE-A is also for pilot applications in a number of countries and regions,but the traditional cellular network still has its limitations,in the cell due to shadow effects and path loss,the quality of communication for all users can't be guaranteed.D2 D is a close-range communication technology and D2 D technology can be used to achieve relay,which enables users with poor communication quality to communicate with base stations through other mobile devices.In this thesis,the key technical problems are studied.This thesis first introduces the LTE/LTE-A communication system related knowledge,including LTE network architecture,wireless frame structure,resource scheduling process and power control,and analyzes the key technologies in D2 D technology and solutions to the problems in D2 D technology,the feasibility and superiority of relaying with D2 D are put forward,and the key problems are discussed.According to the problems that need to be solved,the concrete application scenarios are envisaged and the corresponding solutions are put forward.Then,this thesis proposes a cellular priority resource allocation algorithm in hybrid networks.The algorithm is designed to solve the problem of D2 D technology in the process of using D2 D relay,how to allocate the appropriate resources for D2 D communication.The thesis argues that D2 D communication must have the least impact on cellular communication,including the interference caused by the introduction of D2 D and the increase of cellular user power.It is proved that the algorithm can effectively reduce the interference and reduce the impact of D2 D users on cellular users.Finally,this thesis combines D2 D and Relay to propose a dynamic relay algorithm based on D2 D.The algorithm is designed to solve the problem of communication mode and relay node selection in the cellular network.The algorithm uses the cellular priority resource allocation algorithm as the resource allocation algorithm,taking into account the low mobility of the user and the changing channel,each frame or multiple frames change the allocation of resources once.In the simulation,different D2 D relay scenes are created by changing the location and channel conditions of the UE,and then observe the performance change of the system.Finally,it proves that the algorithm can improve the throughput and spectral efficiency of the system and reduce the energy consumption.