Design, Optimization, and Prototyping of Micro-scale THz Communication Systems Powered by Resonant Tunneling Diode-Based Energy Harvesting

• Applicants: Professor Dr.-Ing. Robert Schober; Professor Dr. Nils Weimann
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556167353

The Internet-of-Things (IoT) has become an integral part of modern human life. However, for certain applications, the comparatively large size of existing IoT nodes is problematic. For example, for on-body IoT networks monitoring vital signs, micro-scale devices are desirable to minimize the patients' discomfort. It is widely expected that such micro-scale IoT devices will operate in the terahertz (THz) frequency band (300 GHz - 10 THz), where small antennas can be employed and an extremely large bandwidth is available. However, although the general concept of the Internet of Nanothings (IoNT) based on THz communication has been proclaimed already in 2010, such micro-scale THz IoT devices are not available today. One limiting factor in this context is the lack of a perpetual power supply for micro-scale IoT nodes. At lower frequencies, wireless power transfer (WPT) from a dedicated energy source has been shown to be a viable option for powering IoT nodes equipped with energy harvesting (EH) circuits. To maximize efficiency, WPT was jointly designed with the information transmission in the downlink and the uplink, leading to the concepts of simultaneous wireless information and power transfer (SWIPT) and wireless powered communication networks (WPCNs), respectively. However, extending these concepts to micro-scale IoT networks employing THz communication and EH is challenging. First, the standard Schottky diode-based EH circuits commonly employed at lower frequencies may not be efficient for THz WPT. Instead, resonant tunneling diodes (RTDs) have been shown to be suitable for operation at THz frequencies. Second, SWIPT and WPCN design is intricately linked to the (generally non-linear) characteristics of the EH circuit. Thus, since the characteristics of RTDs are completely different from those of Schottky diodes, new SWIPT and WPCN design frameworks are needed. Third, the properties of electronic components (not only the EH circuit) depend on the operating frequency. In fact, practical THz local oscillators, signal mixers, and modulators are less stable than those at lower frequencies and introduce phase noise. Fourth, the generation of high-power THz signals is challenging and the path loss of wireless channels grows with frequency. Hence, to harvest significant amounts of energy, transmitter and receiver should be located in close proximity, where near-field effects become relevant. In the proposed project, the applicants tackle the aforementioned challenges in a holistic manner exploiting their combined expertise in theoretical modeling and SWIPT/WPCN design as well as THz hardware design and experimentation with the objective to develop viable concepts for the design, optimization, and prototyping of integrated THz communication and EH systems serving micro-scale nodes.

• DFG Programme: Research Grants