RIS辅助的ISAC系统抗多径衰落及路径损耗方法研究

Research on Methods for Mitigating Multipath Fading and Path Loss in ISAC RIS-assisted Systems

车联网作为未来智慧交通系统中的重要组成部分,对通信和感知的要求也越来越高。通信感知一体化(Integrated Sensing and Communication,ISAC)作为车联网方向极具潜力的一项技术,因可以解决通信场景下的位置感知问题而引起业内的广泛关注。由于城市场景中电磁环境更加随机和不可控,使得当前传统的通信系统架构已经无法满足车-路侧单元(Vehicle-to-Infrastructure,V2I)系统中的通信与感知需求。对此,考虑在传统的V2I系统加入智能反射面(Reconfigurable Intelligent Surface,RIS),将其与ISAC技术结合,构建多径场景下新的被动感知模型。深入分析了在新的被动感知模型下,RIS辅助ISAC通信系统的抗多径性能优化。提出一种大尺寸RIS单元优化分组方法,使部分单元参与信号的反射,并将单元优化分组后的大尺寸RIS与相同单元数的小尺寸RIS进行系统性能对比。仿真结果表明,优化设计大尺寸RIS实现了高于小尺寸RIS大约1.5 bit/s的信号传输效率,在提升系统信号传输性能的同时有效地减少了信道的估计开销。

As an important part of the future intelligent transportation system,the Internet of Vehicles has increasingly high requirement for communication and perception.Integrated Sensing and Communication(ISAC),as a promising technology in Internet of Vehicles,has attracted widespread attention in the industry because it can solve the problem of location perception in communication scenarios.Due to the more random and uncontrollable electromagnetic environment in urban scenarios,the current traditional communication system architecture can no longer meet the communication and perception needs in Vehicle-to-Infrastructure(V2I)system.In response to this,this paper considers adding a Reconfigurable Intelligent Surface(RIS)to traditional V2I system,combining it with ISAC technology,and constructing a new passive perception model under multipath scenarios.Then,it deeply analyzes the optimization of the anti-multipath performance of the RIS-assisted ISAC communication system under a new passive perception model.A large-scale RIS unit optimization grouping method is proposed,which allows some units to participate in signal reflection,and then compares the system performance of the large-scale RIS after unit optimization grouping with the small-scale RIS with the same number of units.Simulation results show that the optimized design of large-scale RIS achieves a signal transmission efficiency of about 1.5 bit/s higher than that of small-scale RIS,effectively reducing the channel estimation overhead while improving the system signal transmission performance.