Indoor Terahertz Communications: How Many Antenna Arrays Are Needed?

Terahertz (THz) communications promise to be the next frontier for wireless networks. Novel solutions should be explored to overcome the hardware constraints and the severe path loss. In this paper, we study a low-complexity indoor THz communication system with antenna subarrays. The Saleh-Valenzuela (S-V) channel model is modified to characterize the THz channel. By exploiting the hybrid beamforming with multiple subarrays, we analyze the ergodic capacity of the system and obtain an upper bound. Furthermore, with the analysis of performance degradation for the uncertainty in THz phase shifters, we provide a guidance on the design of antenna subarray size and number for certain long-term data rate requirements with different distances. Simulation results validate the effectiveness of the ergodic capacity upper bound, and show that the proposed THz system and antenna array structure can efficiently achieve capacity gains and support THz communications.