Wideband Terahertz Communications with AoSA: Beam Split Aggregation and Multiplexing

Array-of-subarrays (AoSA) is an appealing architecture in terahertz (THz) communications since the analog beamformers on subarrays can provide beam gain to combat severe propagation loss, by low-cost phase shifters. However, the traditional beamforming scheme for AoSA, i.e., each subarray serves an exclusive user, cannot cope with the effect of beam split in THz wideband communications. In this paper, we propose a novel concept, i.e., beam split aggregation and multiplexing (BSAM), to support wideband THz communication with AoSA architecture. Specifically, we first characterize the direction of beam split and then derive the maximum bandwidth of a subband that will not cause beam split. Finally, based on the above results, we propose a criterion to plan the subbands and design the analog beamformers for BSAM.