Free Space Optical Communication for Inter-Satellite Link: Architecture, Potentials and Trends

TL;DR

This paper reviews the architecture, advantages, and future trends of free space optical communication for inter-satellite links, emphasizing laser-based systems for high-speed, secure, long-distance satellite communication within 6G networks.

Contribution

It provides a comprehensive overview of laser-based inter-satellite optical communication systems, including technical mechanisms, security features, and future research directions.

Findings

Laser ISLs offer longer distance and higher data rates.

Optical security is enhanced by laser and channel properties.

Open issues include beam steering and integrated sensing.

Abstract

The sixth-generation (6G) network is expected to achieve global coverage based on the space-air-ground integrated network, and the latest satellite network will play an important role in it. The introduction of inter-satellite links (ISLs) can significantly improve the throughput of the satellite network, and recently gets lots of attention from both academia and industry. In this paper, we illustrate the advantages of using the laser for ISLs due to its longer communication distance, higher data speed, and stronger security. Specifically, space-borne laser terminals with the acquisition, pointing and tracking mechanism which realize long-distance communication are illustrated, advanced modulation and multiplexing modes that make high communication rates possible are introduced, and the security of ISLs ensured by the characteristics of both laser and the optical channel is also analyzed. Moreover, some open issues such as advanced optical beam steering, routing and scheduling algorithm, and integrated sensing and communication are discussed to direct future research.