Using Motion Sensors for Improved Beam Tracking in THz Communications with User Micromobility

The terahertz frequency band (0.3-300 THz) is expected to be used in sixth generation (6G) cellular systems providing enormous bandwidth at the air interface. The cellular systems utilizing this band will rely on extremely directional antennas at both base station (BS) and user equipment (UE) to compensate for path losses. However, this property makes links vulnerable to frequent antenna misalignment caused by micromobility, e.g., small shakes and rotations of UE even when a user is in a stationary position. In this paper, we propose a new scheme for efficient beamalignment to reduce the fraction of time in the outage and improve ergodic capacity of the link under UE micromobility. The main idea consists in tracking the displacement of the center of the antenna half-power beamwidth (HPBW) allowing to drastically decrease the search space during the beamalignment procedure. By utilizing real measurements of micromobility patterns, we demonstrated that the proposed the scheme allows reducing the fraction of time in outage by 10-30% and improve ergodic capacity by 5-20% depending on the type of application utilized by the user and the accuracy of utilized motion sensors at UE. © 2022 IEEE.