Space-time-coding metasurface could transform wireless networks with dual-functionality for 6G era

Programmable metasurfaces (PMs), also sometimes referred to as reconfigurable intelligence surfaces, are smart surfaces that reflect wireless signals, but can also dynamically manipulate electromagnetic waves in real-time. These surfaces are highly advantageous for the development of many cutting-edge technologies, including advanced sensing and wireless communication systems.

Researchers at Southeast University, University of Sannio and Université Paris-Saclay-CNRS showed that a specific PM, known as a space-and-time-coding metasurface, could simultaneously support both sensing and wireless communication.

Their paper, published in Nature Communications, introduces two promising schemes for integrated sensing and communication (ISAC) that rely on a space-and-time-coding metasurface they developed.

"Our research was driven by a fundamental question: Can a single device provide high-speed wireless communication while simultaneously sensing its environment?" Tie Jun Cui, one of the senior authors of the paper, told Tech Xplore.

"As we move towards the era of 6G—promising ultra-fast speeds, near-zero latency, and a vast range of new applications—there is an increasing demand for more integrated and intelligent systems. Future networks will need to do more than just transmit data; they must also interact with and respond to their surroundings."

Inspired by their vision of a seamlessly connected future world, Cui and his colleagues set out to develop a new PM that concurrently supports both high-speed communication and real-time sensing of its surrounding environment.

The key objective of their study was to contribute to the advancement of network infrastructures, simplifying their underlying structure, reducing their costs and ultimately allowing them to meet the larger demands associated with 6G technology.

"At the core of our system is a technology called a space-time-coding metasurface—a smart, programmable surface that goes beyond merely reflecting wireless signals," explained Cui.

"Unlike a conventional mirror that passively bounces back light, this surface actively manipulates the signals it reflects. Each element contains diodes that can be switched on or off, dynamically shaping the propagation of electromagnetic waves."

Notably, the metasurface designed by Cui and his colleagues supports both the original frequency of a signal it is interacting with and additional harmonic frequencies, which can be controlled with high precision.

While the original frequency can be used to enable high-quality communication, the controllable harmonics support the real-time sensing of the surrounding environment and the detection of signals of interest via a machine-learning algorithm.

"This dual functionality allows a single device to maintain stable connectivity while simultaneously sensing its environment—tracking movement, detecting objects, and adapting to changes in real time," said Cui.

To assess the performance of their proposed sensing and communication system, the researchers realized a prototype of the metasurface that operates at microwave frequencies, specifically at 10.3 GHz. In initial tests, this programmable surface was found to effectively tackle both communication and sensing tasks.

"We showed that our prototype can dynamically adjust to changes in the environment—tracking moving users, stabilizing connections, and accurately detecting obstacles," said Cui. "Practically, this approach could transform future mobile networks by reducing system complexity and cost, optimizing the use of the available spectrum, and enhancing the overall sustainability of wireless communication infrastructure."

This recent work by Cui and his colleagues could soon inspire other teams to design other similar space-and-time-coding metasurfaces for simultaneous sensing and communication. In the future, the system they developed could be further improved and used for various real-world applications, ranging from smart cities to home security, industrial robotics and autonomous vehicles.

"Looking ahead, we are working on the integration of advanced artificial intelligence at a system level, allowing these smart surfaces to make complex real-time decisions and further enhance both communication and sensing capabilities," added Cui.

"Enhancing security measures remains a critical focus to ensure robust, reliable, and protected operation. Ultimately, our goal is to develop intelligent environments that seamlessly adapt to user needs, transforming everyday spaces—from homes to entire cities—into more connected, responsive, and efficient ecosystems."

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