Research On The Coexistence Technology Of Radar Sensing And Communication Assisted By Reconfigurable Intelligent Surface

The shortage of wireless resource spectrum is attracting widespread attention from both industry and academia with the deployment of 5G.In addition to using higher new frequency bands,people have to think about other methods to alleviate and solve the problem of spectrum resource shortage.Due to the intersection of radar and communication in spectrum resources,various technologies have emerged that share or combine radar and communication spectrum,such as time division frequency system,beam division system,and simultaneous system.Firstly,the time-sharing and frequency-division system refers to the separation of radar and communication in terms of time or frequency,meaning that the two have their own operating time and frequency bands,which is also known as the cooperative system.Secondly,the beamforming system refers to pointing radar signals and communication signals in different directions in space,which can achieve isolation between radar and communication in the spatial domain.Therefore,it is also known as the coexisting system.Since the two generate different waveforms at the same time,they will form interference with each other,so the focus is to develop effective interference reduction methods;Thirdly,the simultaneous system attempts to achieve a fully shared structure and integrates it on a platform through certain scientific methods.Radar and communication use the same signal waveform or orthogonal signal waveform to synthesize a signal waveform,which can be detected by radar while communicating.Therefore,it is also known as the integrated system of radar perception and communication.Nevertheless,the main purpose of traditional radar is target detection and recognition,while the main purpose of traditional communication is information transmission.Therefore,many works combining radar and communication are currently in the theoretical research stage.In addition,the current reconfigurable intelligent surface mainly serves communication functions to improve the performance of communication systems.In recent years,the theory and research work of reconfigurable intelligent surface assisted radar detection and integrated radar perception and communication systems have also begun to emerge.The purpose of this thesis is to study the combination of radar and communication,with a focus on the coexistence technology of the two.One method is to study how to use reconfigurable intelligent surface devices to improve radar detection performance from the perspective of time sharing system.The second method is to use reconfigurable intelligent surface to reduce radar interference on communication systems in scenarios where radar communication and cellular communication base stations coexist.Firstly,in terms of the combination of radar and communication,a detailed overview was given of joint radar perception and communication in the 6G background,basic knowledge related to traditional radar,and research progress in reconfigurable intelligent surface assisted communication.Then,from the perspective of time sharing system,a design concept of reconfigurable intelligent surface is proposed to improve radar detection performance.By extending the configuration of one reconfigurable intelligent surface in the system to two distributed reconfigurable intelligent surfaces,the detection probability of a distributed reconfigurable intelligent surface assisted sensing system is derived,and a simple reconfigurable intelligent surface phase alignment method is proposed.The simulation results show that this scheme can improve the radar target detection probability and meet the radar performance requirements.Secondly,considering the coexistence scenario of radar and cellular communication base stations,in which the reconfigurable intelligent surface mainly assists radar,interference reduction algorithms based on zero space projection were specifically studied.The simulation results show that this scheme can significantly reduce the interference of radar on the communication system to meet the communication transmission rate requirements.Finally,an overview is provided on the potential issues in the integration of radar and communication,and future research directions are also discussed.