智能反射面辅助的MU-MISO车联网毫米波通信联合波束赋形  

Joint Beamforming for IRS-aided MU-MISO Millimeter Wave Communication of Vehicular Network

作　　者：何艺 仲伟志[1] 万诗晴 朱秋明[2] 林志鹏 HE Yi;ZHONG Weizhi;WAN Shiqing;ZHU Qiuming;LIN Zhipeng(College of Astronautics,Nanjing University of Aeronautics and Astronautics,Nanjing,Jiangsu 210016,China;College of Electronic and Information Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing,Jiangsu 210016,China)

机构地区：[1]南京航空航天大学航天学院,江苏南京210016 [2]南京航空航天大学电子信息工程学院,江苏南京210016

出　　处：《信号处理》2024年第2期336-344,共9页Journal of Signal Processing

基　　金：江苏省重点研发计划(产业前瞻与关键核心技术)(BE2022067,BE2022067-1)。

摘　　要：近年来,车联网通信系统提出了大规模数据传输,通信连接稳定等需求。高频段通信凭借超高传输速率,低时延的特点被引入了该系统,但是,高频段通信仍面临着阻塞问题的挑战。因此,智能反射面作为一种可解决高频段通信阻塞问题的技术,成为车联网高频通信的热点议题。智能反射面由超材料构成,其表面的多个无源反射单元均匀排布形成阵列,所有反射单元的反射系数均可通过智能控制器实时调节,控制反射波束的方向和形状,来实现对无线传输环境的智能调控,提供增强视距通信、扩展通信覆盖范围等服务。针对MU-MISO车联网毫米波通信场景下,基站与车辆用户视线通信链路因遮蔽,车辆高速移动等因素,面临随机中断的问题,将智能反射面引入该系统,并结合该系统提出了基于半定松弛问题的交替迭代优化算法,以提高通信稳定性。该方法将系统中基站波束赋形矩阵优化和智能反射面相移矩阵优化分解为两个子问题,通过定义半定矩阵变量并适当放松特定的约束条件将两个子问题近似成为半定松弛问题,随后,使用交替优化技术对其进行迭代求解以实现联合优化,通过最大化同时刻通信车辆中的最小信干噪比来确保通信稳定性。仿真结果表明,该方法显著提高了车辆用户的信干噪比和基站的总频带利用率,确保了动态场景中车辆与基站的通信稳定性。In recent years,the communication-system demands of a vehicle-to-everything(V2X)network have included large-scale data transmission and stable communication connections.High-frequency communication has been introduced into the system,which has the characteristics of an ultra-high transmission rate and low latency.However,high-frequency communication is still troubled by the challenge of blocking.Therefore,as a technology to solve this problem,an intelligent reflecting surface(IRS)has become a hot topic for the high-frequency communication of a V2X network.An IRS is composed of a metamaterial,which contains multiple passive reflecting elements on its surface that are uniformly arranged to form an array.Moreover,the reflection coefficients of these elements can be adjusted in real time through an intelligent controller to control the direction and shape of the reflected beam.This makes it possible to intelligently manipulate the wireless transmission environment and provide services such as enhanced line-of-sight communication and extended communication coverage.The IRS was introduced to resolve the problem of the line-of-sight paths between the base station(BS)installed at the roadside and the vehicle users(VU)being randomly interrupted in the MU-MISO millimeter wave communication scenario of a vehicle-to-infrastructure network as a result of factors such as shielding and the high travel speed of the vehicles.Meanwhile,combined with the characteristics of this system,an alternate iterative optimization algorithm based on semidefinite relaxation(SDR)problems was proposed to improve the stability of the communication quality.This method decomposed the optimization of the base station beamforming matrix and IRS phase shift matrix into two subproblems,which were approximated as SDR problems by defining the semidefinite matrix variables and appropriately relaxing the specific constraints.Then,an iterative solution was obtained using the alternate optimization technique to realize the joint optimization,which ensured co

关 键 词：车联网 智能反射面 联合波束赋形 半定松弛问题 交替迭代优化算法 

分 类 号：TN929.5[电子电信—通信与信息系统]