4 ms·

I'm not sure that's accurate. The article suggests they used three routers, and mention 'interference'. I think you'd perhaps need to be more than a 'bystander'

I'm not sure that's accurate. The article suggests they used three routers, and mention 'interference'. I think you'd perhaps need to be more than a 'bystander' to be able to set up a triangle of WiFi routers around someone's home. Not impossible, of course, but by that point, no longer really a 'bystander'.

transpute 4y ago
Depends on the adversary's objective. The DensePose paper is only one of hundreds of papers on Wi-Fi Sensing for different activities, over ~10 years of funded research, https://news.ycombinator.com/item?id=34485816 https://news.ycombinator.com/item?id=34485816. E.g. keystroke recognition can be done with a single passive receiver, https://news.ycombinator.com/item?id=34485613 https://news.ycombinator.com/item?id=34485613 Some research is less dependent on the training environment, https://techxplore.com/news/2021-11-winect-tracks-3d-human-poses.html https://techxplore.com/news/2021-11-winect-tracks-3d-human-p... > wireless sensing systems .. mostly rely on models that were pre-trained on a fixed set of known activities, thus they can only classify a limited number of human poses or movements .. our system uses signal processing techniques to separate the Wi-Fi signals reflected from each moving limb and track the trajectory of each limb .. Winect could track free-form human activities with centimeter-level accuracy in a variety of challenging environments and scenarios. Dec 2022 survey paper categorized recent research on wireless device-free human sensing, https://dl.acm.org/doi/10.1145/3530682 https://dl.acm.org/doi/10.1145/3530682 > WDHS systems involve three primary sensing task types. The first type, behavior recognition .. second type is movement tracking .. The third type, user identification, leverages the unique features in behaviors to identify who performs the movements .. we believe that more context-aware multi-modal systems will be proposed to handle the complex sensing tasks in real life.
lwhi 4y ago
I read it as three WiFi modules .. such as the three contained in the WIFI router mentioned.
- d1sxeyes 4y ago
  Good shout. I checked the actual paper (here: https://arxiv.org/pdf/2301.00250.pdf https://arxiv.org/pdf/2301.00250.pdf, link in the article is broken), and seems you would need multiple routers: > [...] three WiFi transmitters and three aligned receivers [...]. It should be noted that many WiFi routers, such as TP-Link AC1750, come with 3 antennas, so our method only requires 2 of these routers. So basically, one on each side of the subject, one to transmit the signal, the other to receive, and then you can work out the interference pattern. It may be possible to do the same with the transmitters and receivers on the same physical device by measuring the reflected signal, but that doesn't seem to be what they were testing. It seems that the person needs to be between the transmitter and receiver, so I'm not even sure if triangulation would work, although figure 2 implies that you need the 'line of sight' between the routers to be blocked (three 'transmitter' routers and three 'receiver' routers).
  - justsomehnguy 4y ago
    > (three 'transmitter' routers and three 'receiver' routers). Three Tx antennas and three Rx antennas. You need 3 of them to make a 3d point, otherwise you would have 2d/1d only. Even 1cm difference between antennas placement is more than enough. > It seems that the person needs to be between the transmitter and receiver You receive the direct signal earlier than the reflected one. If you find a way to capture both/only reflections then you can do it without LoS and consequently from only one device (though you would still need at least 3 Tx/Rx pairs.)

transpute 4y ago

Depends on the adversary's objective. The DensePose paper is only one of hundreds of papers on Wi-Fi Sensing for different activities, over ~10 years of funded research, https://news.ycombinator.com/item?id=34485816 https://news.ycombinator.com/item?id=34485816. E.g. keystroke recognition can be done with a single passive receiver, https://news.ycombinator.com/item?id=34485613 https://news.ycombinator.com/item?id=34485613 Some research is less dependent on the training environment, https://techxplore.com/news/2021-11-winect-tracks-3d-human-poses.html https://techxplore.com/news/2021-11-winect-tracks-3d-human-p... > wireless sensing systems .. mostly rely on models that were pre-trained on a fixed set of known activities, thus they can only classify a limited number of human poses or movements .. our system uses signal processing techniques to separate the Wi-Fi signals reflected from each moving limb and track the trajectory of each limb .. Winect could track free-form human activities with centimeter-level accuracy in a variety of challenging environments and scenarios. Dec 2022 survey paper categorized recent research on wireless device-free human sensing, https://dl.acm.org/doi/10.1145/3530682 https://dl.acm.org/doi/10.1145/3530682 > WDHS systems involve three primary sensing task types. The first type, behavior recognition .. second type is movement tracking .. The third type, user identification, leverages the unique features in behaviors to identify who performs the movements .. we believe that more context-aware multi-modal systems will be proposed to handle the complex sensing tasks in real life.

lwhi 4y ago

I read it as three WiFi modules .. such as the three contained in the WIFI router mentioned.

d1sxeyes 4y ago
Good shout. I checked the actual paper (here: https://arxiv.org/pdf/2301.00250.pdf https://arxiv.org/pdf/2301.00250.pdf, link in the article is broken), and seems you would need multiple routers: > [...] three WiFi transmitters and three aligned receivers [...]. It should be noted that many WiFi routers, such as TP-Link AC1750, come with 3 antennas, so our method only requires 2 of these routers. So basically, one on each side of the subject, one to transmit the signal, the other to receive, and then you can work out the interference pattern. It may be possible to do the same with the transmitters and receivers on the same physical device by measuring the reflected signal, but that doesn't seem to be what they were testing. It seems that the person needs to be between the transmitter and receiver, so I'm not even sure if triangulation would work, although figure 2 implies that you need the 'line of sight' between the routers to be blocked (three 'transmitter' routers and three 'receiver' routers).
- justsomehnguy 4y ago
  > (three 'transmitter' routers and three 'receiver' routers). Three Tx antennas and three Rx antennas. You need 3 of them to make a 3d point, otherwise you would have 2d/1d only. Even 1cm difference between antennas placement is more than enough. > It seems that the person needs to be between the transmitter and receiver You receive the direct signal earlier than the reflected one. If you find a way to capture both/only reflections then you can do it without LoS and consequently from only one device (though you would still need at least 3 Tx/Rx pairs.)