Hybrid Beam Alignment for Multi-Path Channels: A Group Testing Viewpoint

Directional beams are key to enabling wireless communications at high-frequency bands such as millimeter-wave and terahertz. Beam alignment (BA) methods allow the transceivers to adjust the directions of these beams in an efficient manner by exploiting the channel sparsity at high frequencies. This paper considers an uplink scenario consisting of a user equipment (UE) and a base station (BS), where the channel between the UE and BS consists of multiple paths. The BS wishes to localize the angle of arrival of each of these paths with a given resolution. At each time slot of the BA, the UE transmits a BA packet and the BS uses hybrid beamforming to scan its angular region. In order to minimize the expected BA duration, a group testing framework is devised, and the associated novel analog and hybrid BA strategies are described. Simulation studies suggest that the proposed schemes outperform the state-of-the-art multi-path BA methods.