Intelligent reflecting surface enhanced indoor terahertz communication systems

Terahertz (THz) band has been envisioned as a promising enabler that achieves high-speed information transmission and provides adequate spectrum resources for future sixth generation (6G) wireless systems. However, due to the extremely high frequency and the strong directionality of THz waves, the wireless communication links in such a frequency range (from 0.1 THz to 10 THz) suffer from serious path loss, multi-path fading, communication interruption and poor coverage. To this end, the intelligent reflecting surface (IRS) is proposed to improve the coverage performance for the indoor THz communication scenarios. Interestingly, the IRS is able to smartly reconfigure the propagation of electromagnetic waves by adjusting the discrete phase shifts of the IRS elements. Although the exhaustive phase shift search scheme can significantly enhance the coverage capability of THz communication, it involves the unacceptable computation complexity. Subsequently, a low complexity phase shift search scheme, called suboptimal search scheme, is proposed by just selecting the partially better combinations of discrete phase shifts. Simulation results show that the proposed suboptimal search scheme is able to achieves the near-optimal coverage performance and greatly decreases the computational burden compared with the exhaustive search method. Moreover, the ray-tracing technique is leveraged to validate effectiveness of the IRS in practical application scenarios.