Low-orbit satellites have the potential to provide high-speed communications to millions of people worldwide, but they are limited by the fact that their antenna arrays can only manage one user at a time. This one-to-one ratio means that companies must launch constellations of many satellites or large individual satellites with many arrays, which is expensive, technically complex, and could lead to overcrowded orbits. SpaceX has taken the constellation route with its StarLink network, which currently consists of over 6,000 satellites and plans to launch tens of thousands more in the future.
Researchers at Princeton engineering and Yang Ming Chiao Tung University in Taiwan have developed a technique that enables low-orbit satellite antennas to handle signals for multiple users simultaneously, reducing the need for additional hardware. The technique involves positioning antenna arrays to direct a beam of radio waves precisely where it is needed, allowing each beam to carry information like texts or phone calls. Unlike terrestrial platforms such as cell towers, low-orbit satellites can only handle one signal per beam due to their high speed and constantly changing positions.
The researchers have developed a system that effectively splits transmissions from a single antenna array into multiple beams without the need for additional hardware, allowing satellites to overcome the single-user limit. This approach is compared to shining two distinctive rays from a flashlight without relying on multiple bulbs, resulting in a significant reduction in cost and power consumption. With fewer antennas needed, this could mean fewer satellites, smaller satellites, or a combination of both, reducing the number of satellites required to cover a particular area.
The impacts of low-orbit satellites in space are a concern due to the limited real estate in the lower layer of Earth’s atmosphere where these satellites are located. With more objects flying around, there is a greater risk of collisions, which can lead to debris breaking apart and causing further issues. The new technique developed by the researchers has the potential to reduce the risk of these hazards as the low-orbit satellite industry continues to grow rapidly, with companies like Amazon and OneWeb deploying their own satellite constellations to provide internet service.
While the research paper outlining the new technique is theoretical, the efficiency gains it offers are real. The researchers have conducted field tests using underground antennas to demonstrate that the math behind the technique works. The next step is to implement this technique in a real satellite and launch it into space to further validate its effectiveness. By incorporating this new approach into existing satellites, companies can design simpler satellites that are more efficient and can handle multiple users simultaneously, leading to a more cost-effective and sustainable approach to low-orbit satellite communications.