Open problems in 6G terahertz communications and networking

Investigate and resolve the primary unresolved questions in terahertz-band (0.1–10 THz) communications for 6G networks, including overcoming short-range propagation (“distance problem”) via ultra-massive MIMO and/or reconfigurable intelligent surfaces, developing accurate beamforming and practical initial access methods for THz ultra-massive MIMO, designing practical and cost-/energy-efficient electronic and photonic transceivers for THz signal generation and detection that are robust to severe hardware impairments (phase noise, non-linearity), creating flexible multi-waveform designs that mitigate hardware impairments at very high frequencies, establishing realistic THz channel and simulation models for link- and system-level evaluation in 6G scenarios, and integrating THz communication with high-accuracy localization and sensing.

Background

The paper identifies terahertz (THz) communication as a key enabler for extreme data rates in 6G owing to the massive spectrum available at 0.1–10 THz. However, THz links suffer from high propagation losses, easy blockages, and severe hardware impairments, which constrain coverage and practicality.

In the authors’ future directions, they enumerate several specific areas requiring further research to make THz viable for 6G: addressing the distance problem with ultra-massive MIMO and RISs, supporting close-proximity services and applications, selecting suitable THz bands, alleviating hardware impairments via multi-waveform designs, advancing practical transceiver design (electronic/photonic, signal generation/detection, RF/antenna), integrating THz communication and sensing, and developing realistic channel and simulation models for robust link- and system-level performance evaluations.