Our world is blanketed in wireless data transmissions. Beacons and towers and base-stations and devices everywhere are sending and receiving and relaying signals to each other through the air via wireless radios.
Over the years, wireless technology has marched forward. New use cases constantly demand higher bandwidth and lower latency and longer range and reduced power consumption. On the surface, these demands are contradictory: for instance, to get better range you can either crank up the power or shift to a lower frequency (increasing latency). The truth is that all of these factors need to be tuned to their physical environment, especially based on the materials and physical structures in the coverage range (such as concrete buildings, drywall interiors, moving vehicles, etc).
The biggest challenge comes from building a generic product that can be used in a myriad of constantly-changing physical environments. To accomplish this, many technologies have evolved that allow wireless radios to adapt to their environment. The wireless radios can detect when transmissions aren't optimized, and automatically tune various factors to improve performance. Smart, right?
Here's the thing researchers are recently discovering, though: the computer that operates the wireless radio, and therefore has raw access to the radio's low-level operating modes and tuning knobs, can actually reconstruct realtime information about the physical environment within the radio's coverage area by watching how the radio adjusts its transmissions. This is known as Channel State Information (CSI) forensics.
What does that mean? It means we're slowly and accidentally evolving wireless networks into surveillance fields. Wireless radios are becoming more and more capable of capturing realtime 3d imagery of their coverage area, including imagery through walls. As companies realize this, they are beginning to see it as a feature rather than a flaw.
So far, the CSI forensics techniques that use off-the-shelf consumer hardware like WiFi routers offer pretty limited functionality. They can be used for presence/movement detection, and rough estimation of floorplan. Some researchers have shown AI-assisted techniques with fuzzy visual imagery through a single wall.
A burgeoning field of research in 6G mobile network development is called "Integrated Sensing and Communications" (ISAC) (sometimes called Joint Communications and Sensing, or JCAS). The state of the art is to augment 6G networks with extremely high frequency (EHF) radios (similar in wavelength to airport body scanners). These radios, when used for data transmission, offer phenomal bandwidth and low latency but poor range and exceptionally poor signal penetration (which, incidentally, is exactly what makes them great for body scanners and 3d imaging).
It turns out that when a network is specifically designed for environmental imaging (cf: when you duct-tape an airport body scanner to your router), it can get a pretty good image. Nokia's press release states:
A very exciting innovation that 6G will bring to the table would be its ability to sense the environment. The ubiquitous network becomes a source of situational awareness, collating signals that are bouncing off objects and determining type and shape, relative location, velocity and perhaps even material properties. With adequate 6G solutions for privacy and trust, such a mode of sensing can help create a “mirror” or digital twin of the physical world in combination with other sensing modalities.https://www.nokia.com/6g/nokias-vision-for-the-6g-era/
A testbed deployment in a German hospital implies that they could literally see a heart beating.
The trio will focus on how sub-terahertz (sub-THz) frequencies could detect human vital signs from a distance, opening the door to a new generation of non-invasive medical monitoring and diagnostic solutions.https://www.nokia.com/newsroom/nokia-fraunhofer-hhi-and-charite-to-collaborate-on-wireless-sensing-solutions-for-healthcare/
Does this mean Telus or Verizon will be watching you in your bedroom in a few years? I don't think so, for two reasons:
But airports, stadiums, and government buildings? Absolutely. Whole Foods, Walgreens, and other physical stores owned by tech firms? Indubitably. What about a wealthy authoritarian surveillance state that runs its own network infrastructure? Any of those come to mind? Hmmm.
The part that disturbs me the most is the inevitability, even in networks that aren't explicitly designed for surveillance. Wireless technology simply cannot keep improving without also making the radio more and more aware of its surroundings. This is not limited to mobile phone networks. We're creating accidental cameras, and they're already everywhere.