Location-Assisted Beam Alignment for Train-to-Train Communication in Urban Rail Transit System

Train-to-train (T2T) communication is expected to increase efficiency of train operation and reduce life-cycle cost in construction for the urban rail transit system. In this paper, we adopt the millimeter wave (mmWave) band to achieve T2T communication and focus on the alignment problem of narrow beams between trains in the turning scene. We first investigate the beam coherence time related to a number of antennas and train speed to avoid misalignment problems and then propose a location-assisted beam alignment method and obtain analog beamforming and combining vectors by comparing the estimated beam deflection angle with the reference phase angle. To validate the proposed algorithm, the numerical results are presented and discussed, where the received signal to noise ratio (SNR), the computational complexity, and the loss rate of the received SNR are assessed. Compared with other search and alignment methods, the proposed algorithm shows significant superiority.