Adaptive Beam Tracking for Mobile Terahertz Massive MIMO Systems

As one of the key technologies in the future 6G system, Terahertz (0.1–10THz) communication has the characteristics of high frequency, large bandwidth, good directionality and high data transmission rate compared with 5G system. However, the large bandwidth brings the problem of beam splitting. Furthermore, the mobility of the user has impact on the alignment of the base station and the user. Some researches based on beam splitting or user movement, without considering both problems. In order to mitigate the effects of beam splitting and user movement in Terahertz massive MIMO systems, this paper establishes a user movement model and proposes an adaptive beam tracking algorithm. Specifically, both uniform and variable speed are considered, then the approximate position of the mobile user can be estimated according to this movement model. Additionally, the adaptive range of the beam can be obtained based on the speed of the user, which can improve the efficiency of the beam tracking. Therefore, the proposed adaptive beam tracking algorithm is utilized to achieve rapid and precise beam tracking and substantially reducing array gain loss. Simulation results show that this scheme can reduce the overhead of beam training and improve the data transmission rate.