Research On Energy Distribution For Maximizing Information Rate In Passive Relay Communication System

With the rapid development and wide application of the wireless communication network,the communication network based on the Simultaneous Wireless Information and Power Transfer(SWIPT)technology has attracted more and more extensive research.This technology solves the problem of frequent charging or replacement of the device battery very well,has greatly extended the working hours of the device,and can be adapted to some special communication environments such as high temperature and high pressure.The relay technology can expand the coverage of the communication network and increase the throughput rate of the system.The SWIPT technology combined with the relay technology can further improve the performance of the communication system.In this paper,the relay communication system based on SWIPT technology is studied,in which the relay nodes have no fixed energy supply and rely on the energy harvested from radio frequency signals to maintain its operation.Two relay energy allocation schemes are proposed to solve the interference problem of the single-user relay system by the interference signals and the problem of unfair user information rate in multi-user relay system,respectively.This paper is divided into two parts:1.For the single-user relay communication system operating in the environment of the interference signals,when the information transmission cannot be carried out normally due to the interference signals,the relay works in the energy harvesting mode and stores the harvested radio frequency(RF)signal energy in the energy storage device till the interference ends.The relay allocates the energy in the energy storage device to the transmission blocks in the subsequent communication period.Two kinds of relay receiver structures,namely,time switching and power splitting,are studied,the optimal energy allocation schemes is proposed,and the user information rate of the proposed scheme is derived.The simulation results show that the proposed scheme can significantly improve the loss of the user information rate caused by the interference signals.2.For the multi-user relay communication system,the relay uses the energy harvested in energy harvesting mode to amplify and forward the information of the users.In this paper,the total information rate maximization model is proposed and the corresponding energy allocation scheme is derived.Through comparison,it is found that the information rate of users who are far away from the relay is significantly lower than that of users who are close to the relay,i.e.,"far-near" phenomenon.For the "far-near" problem,this paper proposes the common information rate maximization model,and derives the corresponding energy allocation scheme of the model.In this model,the information rate of all users is equal,which ensures the fairness of the information rate in multi-user relay communication system.The simulation results show that the energy allocation scheme based on the common information rate maximization model can effectively solve the "far-near" problem in multi-user relay communication system.