Relay Selection Schemes Based On D2D Mode

With the rapid development of mobile communication,people have more and more demands on the transmission rate,delay and throughput of the mobile communication system.D2D(Device-to-Device)communication is a promising technology in the next generation of mobile communications.By using D2 D technology,we can reduce the burdens of the base stations,improve the frequency band utilization and reduce the energy consumption.However,due to the limited transmission distance of D2 D,the direct connection with D2 D can not reflect its advantages.D2 D relay technology can extend the transmission distance of D2 D and improve the QoS of the system,so D2 D relay technology has been widely concerned.But how to choose the right mobile terminal as a D2 D relay in the system needs further study.When we pursue different optimization objectives,the relay selection schemes adopted will also be different.This paper studies the D2 D relay selection algorithm aiming at maximizing transmission rate and maximizing system energy efficiency,and proposes corresponding D2 D relay selection schemes combined with specific application scenarios.The D2 D relay selection based on the maximum transmission rate is studied.We find the factors affecting the ratio of target node n: the social factors which affected by communication frequency of two nodes and their influence of the number of common friends,the distance between two nodes.Therefore,by preprocessing the candidate relay terminals in the cell and combining the optimal stopping theory,we can find the optimal D2 D relay faster,thereby reducing the signaling cost to find the relay.And we can further improve the transmission rate of the system.The simulation results show that the algorithm is more advanced than the traditional algorithms.The D2 D relay selection based on the system energy efficiency maximization is studied.We study the D2 D relay node in the single cell scene to maximize the system's energy efficiency.First,we discuss the scene of the single relay and calculate the location of the optimal relay.Then considering a D2 D relay set to simultaneously transmit data,we propose a dynamic threshold setting algorithm.When the rate provided by the node through the screening does not meet the threshold value,the node can be determined to reduce the overall system efficiency.The simulation results show that the proposed algorithm has better performance in energy efficiency and complexity.Based on the previous theoretical research,this paper puts forward the corresponding application of D2 D relay selection in connection with the vehicle networking and the specific scene of the campus.For the scenario of vehicle networking,traffic information is transmitted between vehicles.It divides the vehicles receiving the same information into the same cluster,and searches D2 D relay to transmit data for vehicles in the cluster.We set the vehicle receiving SNR threshold to determine which vehicles have received the information correctly.And in the second stage,we use these vehicles as D2 D relay nodes to broadcast data for vehicles that do not receive information.In the campus,we proposed the relay selection scheme to maximize the energy efficiency by ensuring the minimum transmission rate.The simulation results show that the proposed scheme has certain advantages.