Research On Full-duplex Relaying Transmission Strategy Based On Polarized Signal Processing In SWIPT System

The development of communication technology and industry has never stopped.After four major revolutions,the fifth generation of mobile communication(5G)is coming.In the 5G era,the scale of mobile users is huge,and the number of mobile devices and infrastructure will also increase significantly.Although 5G will meet the diversified business needs of users in various places,it will also lead to more shortage of spectrum resources and more intense energy consumption.In addition,with the development of communication technologies,more and more wireless devices are used in special environments.In the harsh environment such as toxic or strong acid,or in the human body,it is difficult to supply power for the devices through the grid electricity or frequently replace the battery,resulting seriously restricted in communication quality and equipment life due to the battery capacity.At present,Full-Duplex Relaying(FDR)and Simultaneous Wireless Information and Power Transfer(SWIPT)can effectively solve the above problems.This is because,on the one hand,FDR can simultaneously transmit information at the same frequency and use relay to reduce the energy consumption of the system against path loss.On the other hand,SWIPT makes it possible to simultaneously perform wireless communication and wireless charging.It will broaden the use scenarios of communication devices and effectively reduce the constraints imposed by the battery life on the device and the network.The research work is supported by the Chinese National Natural Science Foundation Project,"Research on Full-duplex Polarization Self-interference Elimination Based on Phase Noise Additive Gaussian"(61501050).In order to make full use of communication resources,reduce energy consumption and increase system capacity,the research studies the joint technology of SWIPT and FDR.Based on the polarized signal processing,the full-duplex relay transmission strategy for SWIPT systems is proposed from the perspective of ideal channel conditions and nonideal channel conditions.The main research work and achievements of the t hesis are as follows:(1)The research summarizes and sorts out the status of SWIPT technology,FDR technology,FDR transmission strategy in SWIPT system and polarized signal processing technology.Firstly,SWIPT technology and FDR technology are studied in detail from three aspects:development history,research status and future challenges.Then the research status of SWIPT full-duplex relay transmission strategy is described.Finally,the basic theory of polarized signal processing technology and related research status are analyzed.(2)Because of the difficulty of achieving self-energy recycling(S-ER)in power splitting transmission strategy,this thesis proposes a full-duplex relay transmission strategy based on polarized signal processing under the ideal channel conditions of SWIPT system.The scheme uses polarized signal processing technology to assign desired signals and loop interference signals to different polarization states,so that the relay can realize S-ER while performing full-duplex communication.In addition,this thesis aims to maximize the system capacity and build the optimization problem,and find the closed solution of the optimal power splitting coefficient.Theoretical analysis and simulation results show that the proposed scheme can not only avoid the loopback interference(LI)affecting the full-duplex communication,but also fully collect the energy in the LI signal,thereby significantly increasing the system capacity.(3)The depolarization effect,cross polarization discrimination(XPD),will adversely affect the transmission strategy based on polarized signal processing in the actual wireless channel.Aiming at this problem,this thesis proposes a full-duplex relay transmission strategy for adaptive channel under the condition that the SWIPT system channel are not ideal.The scheme fully considers the influence of XPD on the transmission strategy,and performs power splitting based on the channel information at the source node,thereby controlling the transmission state of the polarization signal.Thus,the scheme can counteract the influence of XPD.Subsequently,this thesis establishes the optimization problem between system capacity and power splitting coefficient,and proposes the genetic algorithm to obtain the optimal solution.Theoretical analysis and simulation results show that the proposed scheme can adapt to channel changes,and the system capacity can be kept optimal under different XPD effects.