A Survey on Inter-Satellite Links for Low-Earth Orbit Satellite Networks

Traditional satellite communication was limited to specific services such as military communication or broadcasting due to the cost and technical complexity issues. However, thanks to the recent development of satellite launch technology, it is envisaged that future satellite communication supports broadband internet services by deploying tens of thousands of satellites in Low Earth Orbit (LEO). The mega-constellation of the LEO satellite communication system consists of satellite-to-ground communication and satellite-to-satellite communication. In particular, inter-satellite link (ISL) technology for satellite-to-satellite communication is in the early stage, while satellite-to-ground communication technology is relatively mature. Thus, many countries have been getting attention to this ISL technology to accomplish low-latency and high-rate LEO satellite communication. In this paper, we summarize the current status of LEO satellite communication technology, focusing on the ISL technology while providing its future direction.