Ultra Wideband THz IRS Communications: Applications, Challenges, Key Techniques, and Research Opportunities

Terahertz (THz) communication is a promising technology for future wireless networks due to its ultra-wide bandwidth. However, THz signals suffer from severe attenuation and poor diffraction capability, making it vulnerable to blocking obstacles. To compensate for these two shortcomings and improve the system performance, an intelligent reflecting surface (IRS) can be exploited to change the propagation direction and enhance the signal strength. In this article, we investigate this promising ultra wideband (UWB) THz IRS communication paradigm. We start by motivating our research and describing several potential application scenarios. Then we identify major challenges faced by UWB THz IRS communications. To overcome these challenges, several effective key techniques are developed: the time delayer-based sparse radio frequency antenna structure, delay hybrid precoding, and IRS deployment. Simulation results are also presented to compare the system performance for these proposed techniques, thus demonstrating their effectiveness. Finally, we highlight several open issues and research opportunities for UWB THz IRS communications.