User Terminal Segments for Low-Earth Orbit Satellite Constellations: Commercial Systems and Innovative Research Ideas

Despite the rapid and continuous development of communication and networking technologies, the goal of universal connectivity (i.e., the ability to communicate with any user at any time and in any place) is still unrealized. In 2019, a study
[1]
found that 40% of Earth’s regions lack network coverage, which means that there are still 4 billion people on the planet without Internet access. Moreover, even as the COVID-19 pandemic increased the need for online working, learning, and accessing services—and, thus, increased the number of Internet users—2.9 billion people remain offline in developing countries
[2]
. Satellite communications (SatCom) have been emerging as a potential and indispensable solution to extending broadband coverage to underserved areas
[2]
.