RU 2863: Metrology for THz Communications

Since the submission of the Meteracom phase I proposal at the end of 2018, THz communications has been experiencing a tremendous momentum in the scientific community and is today seen as one of the key enabling technologies to satisfy the exponential growth of data traffic volume, THz communications is now seen as a prime candidate for the physical layer of the sixth generation (6G) wireless systems. As data rates in wireless communications are doubling every 18 months, wireless link connections of 100 Gigabit per second, and beyond, will be critical for emerging applications and systems like wireless backhaul and fronthaul, virtual reality, kiosk down-loading, wireless close proximity links, wireless data center links or wireless chip-to-chip communication. In addition to sophisticated transmission schemes, such as spatial multiplexing, high data rates can effectively scale only in THz frequency ranges. Transmission over carrier frequencies in the THz range is, however, not without challenges, and most notably path losses, which are much more pronounced as compared to that at lower carrier frequencies. Therefore, a THz communication system cannot be designed and characterized as a scaled and incremental version of a lower frequency system. For instance, high gain antennas are indispensable to mitigate the high path loss. However, high gain comes only with high directivity. Hence, in mobile scenarios adaptive beam-forming becomes essential. Since receiver and transmitter have to discover each other under such a condition of limited viewing area, this has a critical impact on beam-tracking and acquisition, also known as device discovery. The ultra-high data rates bring new challenges and opportunities with respect to sampling and analogue-to-digital conversion. This means that channel characteristics and system design (modulation design, sampling at ultra-high data rates, symbol structure, RF design and networking aspects) become intrinsically linked and can no longer be considered separately. Circuit design with compact and integrated implementation reinforces this claim this effect especially in the absence of well-defined reference interfaces. It furthermore exemplifies the need for paradigm shifting metrological concepts to predicting the performance of THz communication systems in real-world environments. The capability to perform measurements and to develop metrological concepts to effectively evaluate these measurements are critical to the further evolution of THz communication systems. Building on phase I where we achieved significant results in all project areas, we have identified broad but strongly interlinked research areas in THz system metrology for phase II.