Researchers have made a breakthrough in satellite technology, enabling low Earth orbit satellites to manage signals for multiple users at once, making them cheaper and simpler to design and launch. This innovation could soon provide millions of people worldwide with access to high-speed communications. Currently, these satellites’ antenna arrays can only handle one user at a time, requiring companies like SpaceX to launch constellations of many satellites or large individual satellites with many arrays to provide wide coverage.
However, this approach is expensive and technically complex, leading to overcrowded orbits. The new technique, developed by researchers at Princeton Engineering and Yang Ming Chiao Tung University in Taiwan, allows satellites to overcome the single-user limit by effectively splitting transmissions from a single antenna array into multiple beams without requiring additional hardware. Key individuals involved in this work include H. Vincent Poor, the Michael Henry Strater University Professor of Electrical and Computer Engineering at Princeton, and Shang-Ho (Lawrence) Tsai, professor of electrical engineering at Yang Ming Chiao Tung University.
Overcoming the Limitations of Low-Earth Orbit Satellites
Low-Earth orbit satellites have the potential to provide high-speed communications to millions of people worldwide. However, their antenna arrays can only manage one user at a time, limiting their capabilities and increasing costs. Researchers from Princeton Engineering and Yang Ming Chiao Tung University in Taiwan have developed a technique that enables these satellites’ antennas to manage signals for multiple users at once, making them cheaper and simpler to design and launch.
The traditional one-to-one ratio between antenna arrays and users means that companies must launch either constellations of many satellites or large individual satellites with many arrays to provide wide coverage. This approach is expensive, technically complex, and can lead to overcrowded orbits. For instance, SpaceX has launched over 6,000 satellites in low-Earth orbit as part of its StarLink network, with plans to launch tens of thousands more in the coming years.
The new technique developed by the researchers builds on a common method used to strengthen communications by positioning antenna arrays to direct a beam of radio waves precisely where it’s needed. Each beam carries information, such as texts or phone calls, in the form of signals. While antenna arrays on terrestrial platforms like cell towers can manage many signals per beam, low-orbit satellites have been limited to handling only one due to their high speed and constantly changing positions.
The Challenge of High-Speed Satellites
The satellites’ 20,000 mile-per-hour speed makes it nearly impossible to handle multiple signals without jumbling them. According to H. Vincent Poor, coauthor and Michael Henry Strater University Professor of Electrical and Computer Engineering at Princeton, “For a cell tower to communicate with a car moving 60 miles per hour down the highway, compared to the rate that data is exchanged, the car doesn’t move very much. But these satellites are moving very fast to stay up there, so the information about them is changing rapidly.”
To overcome this limitation, the researchers developed a system to effectively split transmissions from a single antenna array into multiple beams without requiring additional hardware. This allows satellites to overcome the limit of a single user per antenna array, making them more efficient and cost-effective.
A Simpler and More Efficient Approach
The new technique can be incorporated into existing satellites that are already built, according to Poor. However, a key benefit is that it enables the design of simpler satellites with fewer antennas. This could lead to fewer satellites being launched, smaller satellites, or both. As Shang-Ho (Lawrence) Tsai, coauthor and professor of electrical engineering at Yang Ming Chiao Tung University, explained, “A conventional low Earth orbit satellite network may need 70 to 80 satellites to cover the United States alone. Now, that number could be reduced to maybe 16.”
The approach is comparable to shining two distinctive rays from a flashlight without relying on multiple bulbs. As Tsai noted, “Now, that means a huge reduction in cost and power consumption.” This reduction in complexity and cost has significant implications for the satellite industry, enabling more efficient and sustainable operations.
Reducing the Risk of Space Debris
The low-orbit satellite industry is gaining traction rapidly, with companies like Amazon and OneWeb deploying their own satellite constellations to provide internet service. However, this growth also increases the risk of space debris, which can have long-term consequences for the atmosphere and orbit. The new technique has the potential to reduce this risk by enabling fewer satellites to be launched, reducing the likelihood of collisions and debris.
As Poor emphasized, “The concern there isn’t so much getting hit by a falling satellite, but about the long-term future of the atmosphere, and the orbit being clouded up with space debris causing problems.” By developing more efficient and sustainable satellite technologies, researchers can help mitigate these risks and ensure a safer and more responsible use of space.
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