Adaptive Beamforming With Resource Allocation for Distance-Aware Multi-User Indoor Terahertz Communications

Terahertz (THz) communication is envisioned as a key technology for next-generation ultra-high-speed wireless systems. In this paper, we study an indoor multi-user THz communication system with multiple antenna subarrays. To capture the distance-frequency-dependent characteristics of THz channels, we design a hybrid beamforming scheme with distance-aware multi-carrier transmission, including analog beamforming for user grouping and interference cancellation in radio-frequency (RF) domain and digital beamforming with dynamically selected subarrays at baseband. Specifically, an adaptive power allocation and low-complexity antenna subarray selection policy is developed to serve different users at different distances and reduce the cost of active RF circuits simultaneously, where two greedy subarray selection algorithms are proposed. The effectiveness of the proposed adaptive hybrid beamforming and antenna subarray selection algorithms is verified through simulation results, which achieves significant gains over other nonadaptive and non-distance-aware schemes.