6G Wireless Technologies

Discussions on 6G point to one terabit-per-second as a reasonable goal for the peak bit rate of next-generation wireless systems. To meet this goal, the adoption of the sub-terahertz and terahertz bands (from 100 GHz to 10 THz), which can provide ample bandwidth for both communication and sensing systems, has been proposed by academia and industry. Fortunately, in the last decade, the terahertz technology gap has been progressively closed through major advancements in electronic, photonic, and plasmonic technologies. In parallel, the propagation of terahertz signals has been studied through both physics-based and data-driven approaches, debunking some of the established myths. Nevertheless, there are several communication roadblocks that need to be overcome to unleash the spectrum above 100 GHz. In this chapter, a bottom-up approach will be followed to high-light unexpected findings, innovative solutions, and open challenges for terahertz communications and sensing systems on the ground, in the air, and in space.