Unlicensed 60 GHz millimeter band has a great potential in industrial Internet of things (IIoT) owing to its continuous large bandwidth. However, the signal transmission in this band suffers from high propagation loss, thus beamforming is adopted to provide directional gain. With the increasing number of beams, beam alignment and tracking in mobility scenario may incur unacceptable latency and overhead, and the existing beam management mechanism is no longer suitable. To reduce the latency and signaling overhead during beam tracking, we propose a fast beam tracking scheme with the help of trajectory prediction and channel monitoring. More specifically, we firstly quantify the beam coherent time to reduce the frequency of beam searching. Then, a two-stage heuristic trajectory prediction and channel monitoring aided fast beam tracking scheme is proposed to obtain the optimal beam pairs in the process of terminal movement and make sure that the interference on the directional beam is under the limit. Simulation results verify the effectiveness of the beam coherent time and the advantages of the proposed scheme in terms of complexity, outage probability, and effective spectrum efficiency.
Fast Channel Estimation and Beam Tracking for Millimeter Wave Vehicular Communications