Engineers in the US have developed a system that allows millimeter wave signals to overcome blockages while providing high throughput. They believe the technology can help bring a faster version of 5G to homes and workplaces.
Developed by electrical engineers at the University of California (UC) San Diego, the technology offers a solution to overcome a roadblock to make high-band 5G practical for the everyday user: millimeter-wave wireless signals cannot travel far and are easily blocked. through walls, people, trees and other obstacles.
Today’s high-band 5G systems communicate data by transmitting a single millimeter wave beam between a base station and a receiver, such as a user’s phone. But if something or someone blocks the path of that beam, the connection is completely blocked.
“Relying on a single beam creates a single point of failure,” explains Dinesh Bharadia, a professor of electrical and computer engineering at UC San Diego Jacobs School of Engineering.
To address this, the research team came up with a solution: split one laser-like millimeter wave beam into multiple beams and have each beam follow a different path from the base station to the receiver.
The idea was to increase the likelihood that at least one beam will reach the receiver when an obstacle is in the way. So the researchers created a system that can do this and tested it in an office and outside a building on campus.
According to the researchers, the system provided a high-throughput connection (up to 800 Mbps) with 100 percent reliability, so the signal didn’t drop or lose power as the user moved around obstacles such as desks, walls and outdoor sculptures. In outdoor tests, the system offered connectivity up to 80 meters away.
To create the system, the researchers developed a series of new algorithms. One algorithm first instructs the base station to split the beam into multiple paths. Some of these paths take a direct shot from the base station and receiver; and some trails take an indirect route, with the rays bouncing off so-called reflectors — surfaces in the environment that reflect millimeter waves like glass, metal, concrete or partitions — to get to the receiver.
The algorithm learns the best paths in a given environment and optimizes the angle, phase, and power of each beam so that when they arrive at the receiver, they constructively combine to create a strong, high-quality, high-throughput signal. With this approach, more beams result in a stronger signal.
“You would think splitting the beam would reduce the throughput or quality of the signal,” Bharadia said. “But with the way we’ve designed our algorithms, it turns out mathematically that our multi-beam system gives you higher throughput while generally transmitting the same amount of power as a single-beam system.”
The team added that the other algorithm maintains the connection when a user moves or gets in the way of another user. When these things happen, the rays become misaligned. The algorithm solves this problem by continuously tracking the user’s movement and realigning all beam parameters.
The researchers implemented their algorithms on hardware, consisting of a small base station and a receiver, which they developed in a lab at the university’s Center for Wireless Communications. “You don’t need any new hardware for this,” says Ish Jain, a PhD student in electrical and computer engineering in Bharadia’s lab. “Our algorithms are all compliant with current 5G protocols.”
The team is now working on scaling the system to accommodate multiple users.