Empirical investigation of directional beamforming for sub‐THz propagation loss based on 255 GHz indoor office and industrial environment measurements

Abstract

This study presents an empirical investigation of propagation loss characteristics at 255 GHz in indoor office and industrial environments, focusing on the directional beamforming performance under varying beam alignment conditions. Using a wideband channel sounder equipped with Tx and Rx horn antennas, three beamforming schemes are analyzed: (1) the optimal best‐beam pair, (2) ‐th ordered beam pairs, and (3) randomly selected beam pairs. While the best‐beam propagation loss is well characterized by conventional distance‐dependent models (alpha‐beta and close‐in propagation loss models), the ‐th ordered and random beam pairs exhibit converging excess‐loss behaviors. Notably, line‐of‐sight (LoS) links incur substantial penalties under random beam alignments, whereas non‐LoS links incur smaller penalties, reflecting the inherent multipath diversity available in indoor channels. These findings provide experimentally grounded insights into the trade‐offs between beam management overhead and system performance, establishing a foundation for interference analysis and beam management design of future sub‐THz wireless networks.