Research On Relay Selection Algorithms Based On D2D Communication

Along with the users' continuous requirements for improving of communication rate and service quality,Mobile Communication Technology has obtained the rapid developments.Under the condition of limited spectrum resources,how to increase the system capacity has become the main problem of people thinking.As a key potential and optional part of 5G,D2 D communication technology aims to improve the overall systematic performance,perfect the users' experience,and reduce the pressure of cellular network communication.Because of the fact that D2 D communication technology has shown tremendous advantages,colleges and universities,and related organizations pay great attention to it.But when buildings block the signals and the depth fade of the channel,D2 D equipments fail to complete direct communication.The Relay Technology can be adopted under these circumstances.Hence combining the Relay Technology and D2 D communication technology can promote the quality of communication,and whether the smart and proper selection of relay will directly affect the overall performance of the communication system.This thesis focuses on two aspects of D2 D communication relay selection,the concrete research contents are as follows:1.Current studies of D2 D relay selection centers the one-way relay settings,so this thesis focuses on the three-time slots two-way relay selection to assist the selection of secondary D2 D communication scenarios.First,potential relay and cellular users are selected through the screening.Second,aiming to maximize the D2 D link capacity,a joint relay selection and power allocation algorithm is proposed.By optimizing the sending power of each node on the link of D2 D,the algorithm can find out the optimal relay nodes that can maximize the capacity of D2 D link.Finally,by simulation analysis,compared with other algorithm,algorithm proposed in this thesis can more greatly improve the D2 D link capacity and lower the computation complexity.2.Because of the fact that a single relay node can not achieve long-distance communication,so this thesis mainly studied the relay selection problem under multiple jump communication scenarios.In order to maximize the system capacity,this thesis proposes a multiple relay selection algorithm based on maximum capacity.Firstly,this algorithm screens candidate relay according to the constraints of distance and sending power;and then,the whole link relay selection is subdivided into three parts: the first and intermediate jump of relay selection,and jump in the last two relay selection.The first and intermediate jump of relay selection are based on the principle of maximum information channel capacity to select the best relay,while the two hop performance needs to be jointly considered for the jump in the last two relay selection,and thus the relay selection can be completed by selecting the two jump to link capacity of nodes as a relay node according to the maximum and minimum principle.A large number of simulation experiments show that the proposed Relay Selection Algorithm can effectively improve system capacity,and reduce the failure probability of relay selection.