Array Signal Processing Techniques for Terahertz Communications and Sensing

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The demand for wireless throughput and connectivity continues to grow at unprecedented rates, boosted by the popularity of existing applications and the emergence of new ones, such as augmented reality, autonomous vehicles, holographic gaming, or data showers. While the use of mm-wave frequencies in 5G networks will help overcome current spectrum shortage, these newer applications call for further enhancements in data rate, device connectivity, and latency. Aware of these limitations, researchers are now turning their attention to terahertz (THz) communications, within the range from 0.1 to 10THz, as an enabling technology for future 6G networks. Due to the availability of wide swaths of spectrum, THz communications can innately achieve data rates well in excess of 100 Gbps. The short wavelengths of THz signals offer several advantages, especially the possibility to pack several hundreds antenna elements over a small footprint area. In turn, this allows to form transmit/receive beams with very high directivity, and exploit ultra-massive multiple-input multiple-output (UM-MIMO) techniques to significantly improve network capacity. Achieving the full potential of THz communications will ultimately depend on the availability of advanced signal processing techniques that exploit the underlying physical mechanisms of THz propagation and transceiver devices. The long-term goal of the proposed research is the development, performance evaluation and application of new signal processing techniques for THz communications and sensing, with focus on the use of very large-scale antenna arrays for UM-MIMO transmissions over short to medium range links. The short-term objectives are articulated around three avenues: (1) To develop new algorithms and training protocols for estimation of UM-MIMO channel parameters at THz frequencies, including angles of arrival and time differences of arrival, and endow these algorithms with tracking capabilities for applications under mobility conditions; (2) To conceive new design methods for hybrid analog-digital (HAD) UM-MIMO THz transceivers that maximize data rate while ensuring robustness against channel and hardware impairments, and to investigate the use of intelligent reflecting surfaces (IRSs) in combination with HAD transceivers to overcome blockage; (3) To develop new cooperative algorithms for indoor localization and tracking of THz transmitters by exploiting line-of-sight (LoS) measurements from multiple access points, and extend these algorithms to non-LoS (NLoS) scenarios by taking advantage of the diversity provided by multiple IRSs. This program of research will provide key opportunities for HQP training at the MEng and PhD levels, while the main findings will be presented at international conferences and published in highly selective journals.