Multi-Antenna-Enabled 6G Satellite Systems: Roadmap, Challenges and Opportunities

Future 6G communication networks are expected to connect billions of devices worldwide with trust and extreme bandwidth. In this environment, satellites will play a major role. They will extend the coverage region of terrestrial infrastructures and guarantee the anytime, anywhere connectivity which has now become a major policy objective to make the so-called digital society a reality. 6G satellite systems will have to support a multitude of services whose requirements can only be fulfilled by introducing groundbreaking technologies. Multi-antenna-based approaches pave the way to this game-changing step. In this paper, applications of multi-antenna schemes in satellite systems are hence presented, and the main research challenges are discussed. Direct connectivity to handheld devices, ultra-high capacity links and link security enhancement represent promising use cases. As the interest of the multi-antenna technology in 6G goes beyond pure communication scenarios, benefits in the domain of sensing and geolocation are also shortly addressed.