Massive RF Inter-Satellite Links for Massive Non-Terrestrial Networks

The continuous growth of the satellite industry has started an avalanche of satellite services with the accelerated deployment of thousands of non-geostationary orbit satellites. Various constellations and even swarms of small satellites have been proposed to cope with typical challenges of non-terrestrial networks (NTNs), such as heterogeneous traffic demand, scarce radio resources, challenging link budgets, and high implementation complexity. In this context, inter-satellite links (ISLs) represent a promising solution to enhance the cooperation among satellites in terms of the exchange of control information, load balancing, and so on. This article focuses on RF technology for ISL implementation. While this technology is already rather mature, the increasing number of satellites requires many such links to be deployed per satellite, giving rise to a novel paradigm of massive ISLs. This massive connectivity in space poses challenges, which will likely play a major role in future NTN system designs. In this article, we would like to open a discussion on the future of massive ISLs, the likely technology to be used for their implementation, and the potential opportunities for the research community and industrial stakeholders.