Beam Alignment And Beam Tracking Technology For Millimeter Wave Massive MIMO System

Millimeter waves can support data services with low-latency,high-speed and become an important candidate technology for future mobile communications.Narrow beams with high gain are used to compensate for path loss in millimeter waves system.However,the coverage of narrow beams is limited.Beam alignment and beam tracking technology is required to complete beam alignment and establish a communication link before communication.Therefore,precise beam alignment and beam tracking technology has become an important technology for millimeter-wave communication.This paper mainly studies beam alignment and beam tracking as follows.Firstly,Auxiliary beam pair(ABP)is studied,and an ABP-based beam tracking algorithm is proposed for single-user and multi-user scenarios,respectively.In the single-user scenario,a tracking algorithm based on beam multiplexing is proposed.Different from the existing tracking algorithm based on ABP,the algorithm in this paper multiplexes the communication beam as an auxiliary beam in the beam tracking stage,and the base station only needs to generate an additional auxiliary beam,reducing beam overhead? beam tracking can be accomplished without interrupting communications by using a dedicated RF link architecture.In the multi-user scenario,in order to track multiple users at the same time,this paper introduces a multi-mainlobe auxiliary beam.Each mainlobe of the multi-mainlobe auxiliary beam can be used as an auxiliary beam.By designing a multi-mainlobe auxiliary beam pointing to the current user,tracking of multiple users can be realized simultaneously.The simulation results show that the algorithm can reduce the beam overhead by 25%under the premise of approximating the performance of the existing ABP-based tracking algorithms.In the multi-user scenario,the existing ABP-based tracking algorithm cannot track multiple users simultaneously,while the multi-mainlobe auxiliary beam can realize simultaneous tracking of multiple users.The simulation results show that the performance of the multi-mainlobe auxiliary beam tracking algorithm outperforms existing ABP-based beam tracking algorithms.This paper also studies an ABP-based Extended Kalman Filter(EKF)tracking algorithm.The power ratios are approximately linear and suitable for the EKF tracking algorithm.Therefore,the ABP-based EKF tracking algorithm can be studied to make full use of the existing observations to keep track of the user.Compared with the existing beam scanning-based EKF tracking algorithms,the proposed algorithm only uses an ABP,which can effectively reduce the dimension of the observation matrix and the computational complexity.The simulation results show that the EKF tracking algorithm based on ABP can effectively track the user and has better performance than the ABP algorithm.