21923 - SCTE Broadband Aug2023 COMPLETE v1 (1)

100 Vol. 45 No. 3 - September 2023 Issue by Michele Polese, Viduneth Ariyarathna, Priyangshu Sen, Jose V. Siles, Francesco Restuccia, Tommaso Melodia & Josep M. Jornet Dynamic spectrum sharing Sixth-generation wireless networks will aggregate higher- than-ever mobile traf c into ultra-high capacity backhaul links, which could be deployed on the largely untapped spectrum above 100GHz. Current regulations however prevent the allocation of large contiguous bands for communications at these frequencies, since several narrow bands are reserved to protect passive sensing services. These include radio astronomy and Earth exploration satellites using sensors that suffer from harmful interference from active transmitters. Here we show that active and passive spectrum sharing above 100GHz is feasible by introducing and experimentally evaluating a real-time, dual-band backhaul prototype that tracks the presence of passive users (in this case the NASA satellite Aura) and avoids interference by automatically switching bands (123.5–140GHz and 210–225GHz). Our system enables wide-band transmissions in the above- 100GHz spectrum, while avoiding harmful interference to satellite systems, paving the way for innovative spectrum policy and technologies in these crucial bands. The digital transformation of our society is fostered by the availability of a fundamental, invisible, yet scarce resource – the electromagnetic spectrum. Besides enabling information exchange through wireless communications, the electromagnetic spectrum is also a rich source of information through sensing. The nite nature of the spectrum creates competing interests for communications and sensing. These diverging interests, expressed by different scienti c communities, government entities and industries, have led to rigid spectrum allocations from national and international regulatory bodies, such as the International Telecommunications Union (ITU), or the Federal Communications Commission (FCC), dating back to the 1930s. To support more devices and ultra-high capacity applications, 6th Generation (6G) wireless networks will require data rates that are orders of magnitude higher than available today, thus boosting the need for spectrum. While the 5th Generation (5G) of mobile networks uses carrier frequencies as high as 71GHz, 6G will move beyond 100GHz to aggregate data of many mobile users in ultra-high capacity backhaul links. However, communications in this spectrum band are limited by the coexistence of passive users that (i) do not transmit and (ii) only use high-sensitivity Radio Frequency (RF) sensors for Earth exploration, weather monitoring and radio-astronomy. Passive users can be negatively impacted by interference from active transmissions. Therefore, they retain exclusive access to relatively narrow portions of the above-100GHz spectrum, pre-venting the allocation of contiguous chunks with tens of GHz of bandwidth for communications. For example, in the U.S., the largest allocations for active transmissions between technical between active and passive users above 100GHz