About a third of the world’s population, some 3 billion people, have no access to the internet or have poor connectivity due to limited infrastructure, economic disparities and geographic isolation.
Current satellite and ground networks create communications gaps where it would be too expensive to install traditional ground communications equipment due to geography.
High-altitude platform stations – telecommunications equipment high in the sky, on unmanned balloons, airships, gliders and airplanes – could increase social and economic equality by filling internet connectivity gaps in ground and satellite coverage. This would allow more people to fully participate in the digital age.
One of us, Mohamed-Slim Alouini, is an electrical engineer who contributed to an experiment that showed that it is possible to provide high data speeds and ubiquitous 5G coverage from the stratosphere. The stratosphere is the second-lowest layer of the atmosphere, ranging from 4 to 30 miles above the Earth. Commercial aircraft typically fly in the lower part of the stratosphere. The experiment measured signals between pad stations and users on the ground in three scenarios: a person staying in one place, a person driving a car, and a person driving a boat.
My colleagues measured how strong the signal is in relation to interference and background noise levels. This is one of the measures of network reliability. The results showed that the platform stations can support high data rate applications, such as streaming 4K resolution videos, and can cover 15 to 20 times the area of standard terrestrial towers.
Early attempts by Facebook and Google to commercialize platform stations were unsuccessful. But recent investments, technological improvements, and interest from traditional aviation companies and specialized aerospace startups could change the equation.
The goal is global connectivity, a cause that earned the idea of platform stations recognition in the World Economic Forum’s Top 10 Emerging Technologies report in 2024. The international industry initiative HAPS Alliance, which also includes academic partners, is also pursuing that goal.
Fast, cost-effective, flexible
Platform stations would be faster, more cost-effective and more flexible than satellite-based systems.
Because they keep communications equipment closer to Earth than satellites, the stations can provide stronger signals with higher capacity. This would enable real-time communications fast enough to communicate with standard smartphones, high-resolution capabilities for imaging tasks, and greater sensitivity for sensor applications. They transmit data via free-space optics, or light beams, and large-scale antenna array systems, which can transmit large amounts of data quickly.
Satellites can be vulnerable to eavesdropping or jamming when their orbits take them over hostile countries. But platform stations stay within a single country’s airspace, which reduces that risk.
High-altitude pad stations are also easier to deploy than satellites, which have high launch and maintenance costs. And the regulatory requirements and compliance procedures needed to secure places in the stratosphere are likely to be simpler than the complex international laws that govern satellite orbits. Pad stations are also easier to upgrade, so improvements can be made more quickly.
In addition, platform stations may be less polluting than mega satellite constellations, as satellites burn up upon re-entry and can release harmful metals into the atmosphere. Platform stations, on the other hand, can be powered by clean energy sources such as solar power and green hydrogen.
The main challenges for practical platform stations are extending their airborne time to months, boosting onboard green energy, and improving reliability, especially during automatic take-off and landing in the lower turbulent layers of the atmosphere.
Beyond satellites
Platform stations can play a crucial role in emergency and humanitarian situations by supporting relief efforts when ground networks are damaged or out of service.
The stations can also connect Internet of Things (IoT) devices and sensors in remote locations to better monitor the environment and manage resources.
In agriculture, the stations can use imaging and sensor technologies to help farmers monitor the health of their crops, soil conditions and water supplies.
Their ability to capture high-resolution imagery can also support navigation and mapping activities critical to cartography, urban planning and disaster response.
The stations could also serve a dual function, carrying instruments for atmospheric monitoring, climate research, and remotely sensing features of the Earth’s surface, vegetation, and oceans.
From balloons to airplanes
Platform stations can be placed on different aircraft types.
Balloons provide stable, long-term operation at high altitudes and can be tethered or free-floating. Airships, also called dirigibles or blimps, use lighter-than-air gases and are larger and more maneuverable than balloons. They are especially useful for surveillance, communications, and research.
Gliders and powered aircraft can be controlled more precisely than balloons, which are sensitive to variations in wind speed. In addition, powered aircraft, including drones and fixed-wing aircraft, can provide electricity to communications equipment, sensors and cameras.
Next generation energy
Platform stations can use a variety of energy sources, including increasingly lightweight and efficient solar cells, high-energy-density batteries, green hydrogen combustion engines, green hydrogen fuel cells (currently in the testing phase), and eventually laser beams driven by solar stations on the ground or in space.
The evolution of lightweight aircraft design, combined with advances in high-efficiency engines and propellers, are allowing aircraft to fly longer and carry heavier payloads. These advanced lightweight aircraft could lead to platform stations capable of maneuvering in the stratosphere for extended periods of time.
Meanwhile, improvements in stratospheric weather models and atmospheric models make it easier to predict and simulate the conditions under which the platform stations would operate.
Bridging the Global Digital Divide
Commercial deployment of platform stations, at least for post-disaster or emergency situations, could occur by the end of the decade. For example, a consortium in Japan, a country with remote mountain and island communities, has set aside $100 million for high-altitude solar-powered platform stations.
Platform stations could bridge the digital divide by increasing access to critical services like education and healthcare, providing new economic opportunities, and improving emergency response and environmental monitoring. As technological advances continue to fuel their evolution, platform stations will play a critical role in a more inclusive and resilient digital future.
This article is republished from The Conversation, an independent nonprofit organization that brings you facts and analysis to help you understand our complex world.
It is written by: Mohamed-Slim Alouini, King Abdullah University of Science and Technology and Mariette DiChristina, Boston University.
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Mohamed-Slim Alouini has received many grants, mainly from his own university, to work on theoretical aspects of non-terrestrial networks (including HAPS and satellite networks). He is also an academic member of the HAPS Alliance https://hapsalliance.org/ to keep up to date with practical developments in the field of HAPS.
Mariette DiChristina is not an employee of, an advisor to, an owner of stock in, or a recipient of funding from any company or organization that would benefit from this article, nor has she disclosed any relevant affiliations beyond her academic appointment.