Millimeter Wave Beam Alignment And Tracking Method Based On High Moving Scenario

The transmission of large bandwidth data between the automatic vehicles has become the focus research of Internet of vehicles(IoV)in various countries.Millimeter wave(Mm Wave)communication technology has become the key to solve this problem.In order to realize the accurate and fast mmWave communication in the IoV scenario,it is necessary to propose a reliable mmWave beam alignment and tracking algorithm.Therefore,this paper mainly studies the fast and accurate beam alignment and tracking algorithm in the IoV scenario.The main contributions of this paper are as follows.(1)A camera sensing assisted joint offline and online beam tracking(CS-JBT)algorithm is proposed for the line of sight(LOS)scenario.Firstly,the image information obtained by the camera is used to obtain the speed and acceleration information,and build the vehicle mobility model,deduce the vehicle mobility state at the next time through the current vehicle mobility state,to reduce the beam search space.Furthermore,in order to meet the requirements of timeliness,the optimal beam pair in the current mobility state is obtained by using the confidence upper bound(UCB)algorithm in the offline learning stage.Because the sensor error is inevitable,in the online learning stage,the optimal beam in the real mobility state is obtained by the improved ε-greedy algorithm to ensure the accuracy of beam tracking.Software simulation and hardware test results show that compared with the existing algorithms,the proposed CS-JBT algorithm reduces the beam tracking delay from 500ms to 20ms,and achieve a stable throughput of more than 2.5Gbps in the 28GHz band.(2)Intelligent reflecting surface(IRS)assisted mm Wave beam alignment(IRS-BA)algorithm is proposed for the none line of sight(NLOS)scenario.Firstly,the beam alignment problem is modeled as an optimization problem to maximize the spectral efficiency,and the optimization problem is divided into the optimization of beamforming vectors and the optimization of amplitude and phase of the reflectors in the IRS.For the first optimization problem,a mmWave cascade channel estimation algorithm is proposed..According to the obtained mmWave cascaded channel,the beamforming vectors are solved by the alternating optimization.For the second problem,firstly,the solution of the IRS matrix is decomposed into the solution of each reflector.Furthermore,using the alternating optimization,the optimal solution of the amplitude and the phase is obtained.Simulation results show that the throughput of the proposed IRS-BA algorithm is 400Mbps higher than that of the existing algorithms.Finally,this paper summarizes the research content and looks forward to the future optimization direction of the proposed algorithm.