It’s happened to everyone with a cell phone – dropped calls or dead air because service is suddenly unavailable. Or worse, the location pin falls on the navigation app.
Researchers at UBC Okanagan are looking at ways to improve cellphone connectivity and location capabilities by investigating “smart” surfaces that can relay signals from a tower to customers to improve connectivity. A smart surface involves installing reflective elements on windows or panels on buildings in dense urban environments.
The goal, says Dr. Anas Chaaban, is improving wireless services for millions of Canadians. Currently, he says, there are more than 12,000 cell towers. And yet, a lack of cellular service is a common problem.
“The increasing use of mobile technologies around the world requires research that unlocks potential new approaches within our existing infrastructure,” says Dr. Chaaban, assistant professor at the UBC Okanagan School of Engineering. “Although cell towers dot the rooftops of major cities and handle the data and voice traffic of millions of Canadians every day, there are still gaps in service.”
dr Chaaban and his team at UBCO’s Communication Theory Lab have developed transmission schemes that would integrate reconfigurable intelligent surfaces – smart surfaces – in urban centers to serve as reflectors within existing wireless networks.
A reconfigurable intelligent surface (RIS) is a sheet of many individual reflective elements, each of which can modify and reflect an incoming signal. This modification can be controlled with an electrical signal, allowing the RIS to improve the connection or generate signals useful for locating users on the network.
Researchers developed a new localization system that allows a RIS to act as a satellite to improve accuracy. By making a surface smart, it can relay signals to cellphones, which in turn can use those signals to generate an accurate estimate of location, he says. Accurate location estimation is useful not only for location services, but also for improving transmission from tower to phone using optimized location-aware transmission schemes that also leverage the RIS.
“Users never expect a disconnect, and they also expect blazing-fast data speeds,” he says. “To do this, however, the networks have to be constantly updated.”
Researchers tested their theory using multiple modulated RISs, allowing simultaneous localization of multiple users with low complexity for each RIS. They also developed and tested RIS-enabled transmission schemes that outperform existing schemes.
“We simulated the proposed localization protocol and demonstrated its effectiveness in an urban microcell urban canyon scenario,” he explains. “And the protocol works for multiple users at the same time. Even in areas with interrupted service, data can be shared and users can be located and enjoy a reliable connection.”