Vision-aided Positioning and Beam Focusing for 6G Terahertz Communications

To meet the ever-increasing data rate demand in 6G, terahertz (THz) ultra-massive (UM) multiple-input multiple-output (MIMO) system has gained much attention recently. One notable aspect of this system is that the deployment of an extremely large-scale antenna array and high transmission frequency result in an expansion of the near-field region where the electromagnetic (EM) radiation is modeled as a spherical wave. In the near-field region, the channel becomes a function of a position, giving rise to a beam focusing operation that focuses the signal power onto the specific position. However, the traditional approaches relying on the sweeping of discretized beam code-words cannot support this ultra-sharp beam focusing operation in THz UM-MIMO systems. In this paper, we propose a novel beam focusing technique based on the sensing and computer vision (CV) technologies. Essence of the proposed scheme is to extract the mobile’s position from the vision information using the CV technique and then generates the focusing beam directed towards the extracted position. By replacing the discretized and time-consuming beam sweeping operation with a highly precise CV-based positioning, the positioning accuracy as well as the beam focusing gain can be improved significantly. From the numerical evaluations, we show that the proposed scheme achieves significant positioning accuracy and data rate gains over the conventional codebook-based beam focusing schemes.