Wireless networks acting as sensors and providing a more agile alternative to radar is gaining traction. With the rollout of 5G in 2019 and the availability of large-scale antenna rays, we can create radio beams not only to extend coverage towards individual handsets, but also to comprehensively sweep an environment and provide a map of objects within it such as cars, robots, and even people.
And wireless technologies are already being effectively explored in healthcare settings. Nokia Bell Labs recently joined forces with Fraunhofer HHI and Charité to research the use of beamforming technologies to sense vital signs of individual patients in a hospital ward. This could strip away the need for restrictive cables and monitors that tether patients to one place and possibly even enable remote monitoring at home.
The concept of networks that sense is not restricted to wireless sensing. It has been known for over half a century that optical fibers can be used not only for communication but also for sensing. The first patent for fiber optic sensing—where light pulses are transmitted through optical fibers and used to detect environmental changes in temperature, strain, or vibration—dates back to 1960.
State-of-the-art distributed acoustic sensing (DAS) allows for sensing on a fiber optic cable by sending out optical pulses at one end of the fiber, and measures how this light changes thousands of times per second due to acoustic vibrations at each piece of the fiber. This process, known as Rayleigh Backscatter, is limited, however, to 100 kilometers.
The breakthrough invented by Nokia Bell Labs is a new concept based on optical frequency domain reflectometry (OFDR) that allows for fiber sensing over distances of thousands of kilometers in subsea cable by crossing multiple optical amplifiers. This solution has been instrumental in unlocking new avenues of sensing innovation. Efforts to turn subsea telecom cables into sensors that detect extreme weather events or marine activity, for example, rely upon the technology. There are currently 500 subsea cables active or under-construction, stretching for more than a million kilometers, an increasing proportion of which have switched to fiber optic rather than copper cables. This vast ecosystem could now become a tool for sensing minute changes in reflected light to identify mechanical waves and predict tsunamis or earthquakes before they wreak devastation.
“Currently, state-of-the-art tsunami detection is a buoy floating 100 kilometers offshore which provides the warning too late,” says Peter Vetter, president of Bell Labs Core Research at Nokia. “But we have these fibers deep in the ocean which could provide an earlier warning, and that’s of real interest to governments.” These same networks could also sense sabotage by listening for surreptitious underwater activity.
“Thanks to our massive interconnectivity and the massive scale deployment of sensors that have become so affordable and cheap, we are increasingly exploiting sensing along all possible modalities.”Peter Vetter, President of Bell Labs Core Research, Nokia
Even more cutting-edge is early work into quantum sensing as a way to detect previously immeasurable natural phenomena.
“With quantum sensing we can create highly sensitive sensors with, for instance, the ability to detect magnetic fields with much higher sensitivity than present-day technology,” says Vetter. “The possible future applications for this could be MRI scans that deliver much higher accuracy and a much higher level of sensitivity.”
It’s against this backdrop of an already diverse and disruptive pipeline of innovations that we anticipate the rollout of both optical and wireless network sensing in the 6G era.
Many network providers have dubbed it a core feature of their own 6G development plans and—if it becomes reality—this concept of integrated sensing and communication (ISAC) is set to mark a further paradigm shift.
“With quantum sensing we can create highly sensitive sensors with the ability to detect magnetic fields with much higher sensitivity than present-day technology. The possible future applications for this could be MRI scans that deliver much higher accuracy and a much higher level of sensitivity.”Peter Vetter, President of Bell Labs Core Research, Nokia
As the researchers at Stuttgart are looking to demonstrate, expanding sensing capabilities to each point the network touches makes it possible to construct a dynamic digital twin of our physical surroundings, allowing us to see around corners and through walls. The potential applications span industry, infrastructure, and public safety.
Expediting such possibilities is in part why the EU set aside €127 million for 16 projects working in 6G research and development in 2024, and why the US Defense Department’s FutureG office has spoken openly about its own experimentation with ISAC as a military tool that could assist in areas such as drone detection. Both economic powers are looking to gain a first-mover advantage as sensing technologies take on a new dimension.
“We are at a tipping point for sensing technologies,” says Vetter. “Thanks to our massive interconnectivity and the massive scale deployment of sensors that have become so affordable and cheap, we are increasingly exploiting sensing along all possible modalities. They’re already being deployed everywhere that a network can interconnect them. But now, in addition to that, the network can be used as a new sensing modality, the combination of which can augment our real-time understanding of the physical world.”
Having access to such real-time information paves the way for a digital sixth sense with enormous transformative potential.
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