Research On Optimized Transmission Strategies In Heterogeneous D2D Cooperative Networks

With the development of the mobile communication and the increasing popularity of smart devices,the number of requests initiated by users has grown exponentially.At the same time,users have increasingly higher requirements for quality of service.How to improve the overall service performance of the network based on the existing basic network architecture has become one of the major challenges for the current wireless communication network.The D2D communications(Device-to-Device communications)and relay technology are considered as key technologies to improve the communication quality of the 5G cellular network.D2D communication technology is a short-range,end-to-end communication technology with the benefit of low latency,high transmission rate,and high spectrum utilization.The relay technology can expand the coverage of networks and terminals,improve the service quality of edge users,and increase the transmission rate.Therefore,under the 5G cellular system,using D2D technology and relay technology can effectively improve the quality of network services.This paper focuses on the self-property issues in existing D2D communication and the performance of untrusted relay transmission based on energy harvesting.The main contents are as follows:(1)In the D2D cooperative communication network,there is no effective incentive mechanism between terminal devices.Terminal devices are often unwilling to sacrifice their own interests to provide information for other devices.Based on this situation,we have designed a pricing mechanism to provide a basis for the cooperation between devices.The terminal device can decide whether to transmit with other terminal devices according to the obtained revenue.At the same time,the use of MDS(Maximumdistance separable)encoding encodes the file in the terminal device to improve the efficiency of the caching transmission.By optimizing the variable pricing factor and the number of files cached in the terminal device,the optimization goal of minimizing the communication transmission cost of the system is achieved.The simulation results prove that the D2D transmission strategy based on the MDS coding and pricing mechanism can reduce the communication transmission cost of the system and reduce the power consumption of the terminal devices.(2)Under the scenario of one-way and two-way transmission,the communication performance of the untrusted relay is studied based on the simultaneous wireless information and power transfer(SWIPT).In the system model,two communication nodes cannot communicate directly and need to amplify and forward information through an untrusted relay.Two types of relay eavesdropg modes are discussed: active eavesdrop mode and non-active eavesdrop mode.In a delay-sensitive scenario,the outage probability is minimized by optimizing power allocation and power splitting ratio.In delay-insensitive scenarios,the optimization problem is a non-convex problem,and we use Lagrange dual and propose an iterative algorithm to maximize the security rate.The simulation results compare the difference in system performance between one-way and two-way relay,active and passive eavesdropping modes,and prove that the proposed power algorithm can effectively increase the secrecy rate of the system.