Scientists in Germany have demonstrated a startling new form of surveillance: identifying people using nothing more than ordinary WiFi signals. By analyzing how radio waves bounce around a room, researchers can effectively “see” and recognize individuals — even if they are not carrying a device and even if their phone is turned off.
Any reason this wouldn’t work with cell towers?
Despite what others have said. It could in theory. But could it work with ordinary cell towers today, probably not. I base this on the accuracy of current location tracking by cell towers. They still use triangulation from my understanding, and aren’t highly accurate at that. The space your phone could be in is large enough for many people to be. So the granularity just isn’t there.
This is probably because of the large range they cover compared to the power levels they use. But in theory if the density of towers were higher, and the power levels were increased, they could probably do it in at least some locations with the perfect conditions.
There is another potential issue, which is the frequency. The lower the frequency, the less it will interact with an obstacle including people.
Yes, it wouldn’t really.
Right now the way this works is that a human body absorbs a certain about it wifi signal, so of the signal strength in a room dips and comes back up, someone walked through the room, for example. Couple this with what IPs and MAC addresses the router is connecting to, and Verizon can tell “human with laptop,” or “human watching TV.” So just “human body” or dog/cat are what it can detect. Verizon does try and sell this as a feature, as in a shit security feature.
So for cell towers, they’re too far from people in an already chaotic environment to really be useful. Trees, cars, and a million other things can throw off trying to detect already minute changes in signal density. Not to mention that the signals from cell towers are much stronger, so harder to detect the changes.
The imaging argument is just using 2.4GHz as a distance sensing radar, then using the normal transmitted wifi signal as the sender. In order to get the kind of image in the article’s illustration, they’d have to “beam sweep” the room, something that cell towers only do to a very limited degree (not nearly enough resolution to distinguish a FedEx truck from a mini-bus of similar size), and home WiFi barely do at all (I think some home wifi may do a little beam steering, but again, with nothing like that resolution shown.)
So, if the spies wanted to create a special (super costly) WiFi access point, it could “look like ordinary wifi” to an unsophisticated signal sniffer, but get these kinds of images. It also would be outrageously expensive as compared to an ordinary access point… unless they mass produce them…
Yes, however do you remember the big fuss over 5g tower tech coming from Huawei and how that is a security issue? Well turns out the 5g towers can employ beam forming for better connection with each phone. And the interesting thing is that AESA radars work much the same - so you can imagine what a nation wide network of these towers would provide for china in terms of air traffic information
Sure, but why bother?
Practically speaking, we all carry trackers in our pockets, attached to our phone number, email and social media. We already consent to giving away all that data, which basic ping triangulation also allows for fairly granular location tracking.
The wifi tracking method is helpful because it very granular in an otherwise opaque area. It tracks based on body size, who does what around the house, who specifically watched what on TV.
In that last comment, they said air traffic information. So think military aircraft movements.
I imagine resolution decreases with range
Edit: resolution not revolution
Revolution should increase the closer you get to a billionaire.
There’s no need, they can use triangulation since you’re almost always near your phone
I think the main advantage with the wifi-based approaches is that they are usually used in a relatively static/calm indoor environment with a stable channel response and your motions are disturbing that, compared to a quickly changing outdoor environment (e.g. a city) where it would be much harder to distinguish individuals. Also, you are typically closer to the access points, making the power/SNR higher. Regarding mobile communication though, the trend is towards higher frequencies and smaller cell sizes which also give greater spatial resolution (and higher power) and some funky near-field effects can be used to get beam forming on crack: https://arxiv.org/abs/2407.10147 So perhaps it could work even better, wouldn’t be surprised