A Survey on Non-Geostationary Satellite Systems: The Communication Perspective

Abstract

Non-geostationary (NGSO) satellites are envisioned to support various new communication applications from countless industries. NGSO systems are known for a number of key features such as lower propagation delay, smaller size, and lower signal losses in comparison to the conventional geostationary (GSO) satellites, which will enable latency-critical applications to be provided through satellites. NGSO promises a dramatic boost in communication speed and energy efficiency, and thus, tackling the main inhibiting factors of commercializing GSO satellites for broader utilizations. However, there are still many NGSO deployment challenges to be addressed to ensure seamless integration not only with GSO systems but also with terrestrial networks. These unprecedented challenges are discussed in this paper, including coexistence with GSO systems in terms of spectrum access and regulatory issues, satellite constellation and architecture designs, resource management problems, and user equipment requirements. Beyond this, the promised improvements of NGSO systems have motivated this survey to provide the state-of-the-art NGSO research focusing on the communication prospects, including physical layer and radio access technologies along with the networking aspects and the overall system features and architectures. We also outline a set of innovative research directions and new opportunities for future NGSO research.

Scalable Cell-Free Massive MIMO Networks With LEO Satellite Support

“…Unlike [21], this work focuses on the downlink (DL) of LEO deployments operating on the S-band (2.2 GHz), as this allows the direct LEO-to-MS communication (i.e., satellite-to-handheld terminal) without the need to route traffic through a satellite gateway. While the available S-band spectrum is much narrower than that in the Ka/Ku bands (i.e., 30 MHZ rather than 250 MHz), this frequency band allows user terminals to share the RF frontend with that devoted to a sub-6 GHz terrestrial segment, thus significantly easing the implementation of dual terrestrialsatellite handsets [31].…”

Adaptive Beam Pattern Selection and Resource Allocation for NOMA-Based LEO Satellite Systems

“…Low earth orbit (LEO) satellite systems are envisioned as one of the promising solutions for coverage extension in the upcoming beyond 5G (B5G) and 6G era [1]. To deliver exponentially growing traffic and support ubiquitous connectivity, the industry is in the process of deploying hundreds or thousands of LEO satellites in the space [2], e.g., SpaceX Starlink.…”