Integrated Sensing and Communications Enabled Low Earth Orbit Satellite Systems

Extreme crowding of electromagnetic spectrum in recent years has led to the emergence of complex challenges in designing sensing and communications systems. Both systems need wide bandwidth to provide a designated quality-of-service thus resulting in competing interests in exploiting the spectrum. Efficient spectrum utilization has led to the emergence of Integrated Sensing and Communications (ISAC) systems, an approach listed for beyond 5G networks. Several seminal works focusing on the physical and medium-access layer as well as system aspects of ISAC have appeared in the literature already. These works largely focus on terrestrial communications and the use of near-earth objects like Unmanned Aerial Vehicles (UAV)s. The focus of this work is to explore the ISAC in the emerging massive Low Earth Orbit (LEO) satellite systems, leveraging on their low latency, density, ubiquitous coverage and ease of integration. In particular, two aspects of the ISAC: opportunistic and optimized will be highlighted in this work through the use of LEO satellites for positioning as well as the use of Rate-Splitting Multiple Access (RSMA) technique optimized to address sensing and communication requirements.