HAPS as a coverage alternative in low-density territories
High-altitude platforms, known by their English acronym HAPS (High Altitude Platform Stations), operate in the stratosphere at altitudes of between 17 and 22 kilometres. Unlike satellites in low or medium orbit, their quasi-stationary position over a given geographical area allows a stable coverage footprint to be maintained without the propagation delays characteristic of geostationary orbits. This feature positions them as a technically coherent option for providing connectivity in environments where the deployment of terrestrial infrastructure is economically unviable, as is the case across extensive rural and peri-urban areas of the European geography and, in particular, of the Iberian Peninsula. The central argument for considering HAPS in low-density territories is not solely one of coverage, but of infrastructure cost per user served. The laying of optical fibre in areas with densities below operational profitability thresholds requires sustained public subsidies or falls entirely outside the reach of private operators. In this context, a HAPS platform can cover an area on the order of hundreds of square kilometres from a single aerial node, reducing dependence on distributed terrestrial infrastructure and simplifying the network architecture in the access segment. From a technical standpoint, HAPS systems present limitations that condition their operational design. Platform stability under adverse meteorological conditions in the stratosphere, energy management in solar-propulsion platforms, and the coordination of radio spectrum with other systems are engineering factors that determine the viability of continuous service. The ITU has established specific spectrum allocations for HAPS in certain bands, and compatibility with existing terrestrial and satellite systems requires rigorous frequency planning that operators must address during the network design phase. At the European regulatory level, the Digital Connectivity Agenda and the objectives of the Digital Decade 2030 set broadband coverage targets that explicitly include rural areas. HAPS can be integrated into critical infrastructure financing frameworks as a complement to low-orbit satellite technologies and next-generation terrestrial networks, provided that the quality-of-service, latency and availability requirements are defined with precision in the corresponding technical specifications. The operational maturity of these systems and their positioning within the applicable aeronautical certification schemes are factors that operators and institutions must evaluate rigorously before incorporating them into their deployment plans.
NASSAT - Network Satellite Systems