Terrestrial networks for in-flight coverage Standalone mobile operators implementations: ecosystem, radio design considerations, spectrum coexistence, techno-economic feasibility study

In this paper we set to answer the following main question: is there a case for the regular mobile operators to develop standalone subnetworks or to extend their terrestrial networks in order to provide almost seamless in-flight experience for their customers? Both, technical and economic perspective have to be considered. Several derived topics are treated within our study leading eventually to the main answer: Can we leverage the existing key assets present in traditional mobile networks, especially spectrum, as well the existing infrastructure, in order to provide in-flight broadband connectivity? Is it indeed mandatory to use a dedicated spectrum for such an implementation? Do we mandatory need a joint satellite-terrestrial network to provide services for the continental flights? Do we need a dedicated equipment within the aircraft to act as a relay-agent? Does it worth to trigger a possible standard evolution in regards with the smartphone evolution to support, in some conditions, special algorithms mitigating the Doppler effect? First, we present an overview of the terrestrial networks offering broadband services in continental aircrafts and key points considerations for the radio design of such a network. Then, by formulating divergent thinking questions, we challenge some of the key assumptions present in the current implementations. In the end, a schematic techno-economic use case is presented. Our analysis shows that it is feasible to design a network for in-flight coverage by leveraging existing assets. We provide insights and we sketch the requirements for a terrestrial-only network that shares the spectrum between on-the-ground and in-the-air users and, in some conditions, doesn't require additional equipment installed on the aircraft. Financial assessment shows good payback period. While much work remains to be done, we consider this promising results to be the basis for further exploration and eventually possible standard evolutions.