Optimising the LEO satellite communications link through hybrid-ARQ techniques

Satellites in low Earth orbit (LEO) are accessible to an unprecedented number of users around the globe with numerous applications, especially with the recent rapid development in LEO satellite constellations for communications. Until a few years ago, advanced designs for satellite communications systems had focused on conventional geostationary Earth orbit (GEO) communications technologies which are not necessarily tailored to the LEO environment. Such sub-optimal designs were accommodated by the typical application of LEO satellites-remote sensing satellites-normally being large satellites with ever-increasing power and bandwidth and equipped with large ground stations. These days, the current trend of the satellite industry is towards smaller satellites and smaller terminals, made possible through continuous technological improvement. Advances in sensor and payload technology have permitted rapidly increasing amounts of data to be transferred. This, coupled with user demands for reliable, efficient data delivery from small satellites to even smaller terminals, calls for an urgent need to optimise the LEO communications link, particularly for payload data retrieval.