Simple shift could make low Earth orbit satellites high capacity | Science & Technology

The one-to-one ratio means that companies must launch either constellations of many satellites, or large individual satellites with many arrays, to provide wide coverage. Both options are expensive, technically complex, and could lead to overcrowded orbits.

For example, SpaceX went the “constellation” route. Its network, StarLink, currently consists of over 6,000 satellites in low-Earth orbit, over half of which were launched in the past few years. SpaceX aims to launch tens of thousands more in the coming years.

Now, researchers at Princeton engineering and at Yang Ming Chiao Tung University in Taiwan have invented a technique that enables low-orbit satellite antennas to manage signals for multiple users at once, drastically reducing needed hardware.

In a paper published June 27 in IEEE Transactions on Signal Processing, the researchers describe a way to overcome the single-user limit. The strategy builds on a common technique to strengthen communications by positioning antenna arrays to direct a beam of radio waves precisely where it’s needed. Each beam carries information, like texts or phone calls, in the form of signals. While antenna arrays on terrestrial platforms such as cell towers can manage many signals per beam, low-orbit satellites can only handle one.

The satellites’ 20,000 miles-per-hour speed and constantly changing positions make it nearly impossible to handle multiple signals without jumbling them.

“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,” said co-author H. Vincent Poor, the Michael Henry Strater University Professor in Electrical and Computer Engineering at Princeton. “But these…