Active Reconfigurable Intelligent Surface-Aided Terahertz Wireless Communications

Terahertz (THz) communication is expected to be a key technology for future sixth-generation (6G) wireless networks. Furthermore, reconfigurable intelligent surfaces (RIS) have been proposed to modify the wireless propagation environment and enhance system performance. Given the sensitivity to blockages and limited coverage range, RIS is particularly promising for THz communications. Active RIS can overcome the multiplicative fading effect in RIS-aided communications. In this paper, we explore active RIS-assisted THz communications. We formulate the ergodic rate, considering factors associated with active RIS, including active noise and signal amplification, and THz signals, including molecular absorption and beam misalignment