MIT Demonstrates Accurate Single AP Location Method

[thiggins]

In a new paper, a research team led by Professor Dina Katabi present a system called Chronos that enables a single WiFi access point to locate users to within tens of centimeters, without any external sensors.

http://news.mit.edu/2016/wireless-tech-means-safer-drones-smarter-homes-password-free-wifi-0331

 

[sfx2000]

neat stuff...

 

[L&LD]

Existing localization methods have required four or five WiFi access points. This is because today’s WiFi devices don’t have wide enough bandwidth to measure time-of-flight, and so researchers have only been able to determine someone’s position by triangulating multiple angles relative to the person.

The quote from the article seems to suggest this isn't possible with existing WiFi?

Seems like a tech that will not see the light of day anytime soon.

 

[stevech]

In a new paper, a research team led by Professor Dina Katabi present a system called Chronos that enables a single WiFi access point to locate users to within tens of centimeters, without any external sensors.

http://news.mit.edu/2016/wireless-tech-means-safer-drones-smarter-homes-password-free-wifi-0331

I can comment as one who has done a lot of work with 802.11 WiFi location systems... that the news release has many inaccurate statements and terminilogy. Some 5 years ago, Ekahau began selling a location system based on time difference of arrival (TDOA), where 2+ WiFi devices (for location) correlate their measurements and use a high precision common clock to get the time difference. This forms an "interferometer" - a technique in use for decades in RF and optics. Since then several other TDOA products have gone to market, for WiFi, and for UWB (e.g., Time Domain Tech.). A single receiving station can estimate time of flight and thus range. If it moves to well known locations, it can estimate location - if the emitter cooperates. But the usual technique is to use 2-3 receivers all measuring at the same time, in case the emitter is moving. Another term is trilateration. That's been used for many years in aircraft navigation.

I hope M.I.T. did their prior-art research.

 

[sfx2000]

I can comment as one who has done a lot of work with 802.11 WiFi location systems...

Same here - and I'll add that some have been exploring WiFi as Radar seeing on the other side of a wall...

 

[stevech]

http://www.ekahau.com/real-time-location-system/solutions

Hospitals use it "where's the nearest calibrated IV pump"
many other examples.

The Z axis is really hard, e.g., which floor in an office building. That's what I concentrated on in past projects.

 

[sfx2000]

http://www.ekahau.com/real-time-location-system/solutions

Hospitals use it "where's the nearest calibrated IV pump"
many other examples.

The Z axis is really hard, e.g., which floor in an office building. That's what I concentrated on in past projects.

Well, yes and no...

Had a bit of scare* about a year ago (rightfully so, take care of your heart) - the hospital I spent a few days with - they were very connected... 24/7 on their WLAN, and digging into things once I felt a bit better, they actually had a clue or two as far as network security...

* yes, one of those things - some don't make it - I did...

 

[kvic]

The actual paper: https://www.usenix.org/system/files/conference/nsdi16/nsdi16-paper-vasisht.pdf

 

[kvic]

The quote from the article seems to suggest this isn't possible with existing WiFi?

They're using commercially off-the-shelf WiFi hardware. The meat is in their software, Chronos.

Seems like a tech that will not see the light of day anytime soon.

I would think so. It's a very interesting idea and makes a good paper for conference. But far from deployment.

I think the innovation here is making use of the whole bandwidth of WiFi in 2.4Ghz and/or 5Ghz for localization purpose (albeit for very short period per request). But as people could imagine and the authors rightly point out in their paper it'll have impact on normal traffic between the AP (and adjacent APs) and clients.

They seem to down play the adverse impact (or maybe not enough research in their project yet).

 

[System Error Message]

I've heard of projects like this and ones about seeing whats behind the wall and in medical. Thing is 5Ghz is used for radar so theres no reason why you couldnt do the same with existing wifi. Arduino's radar module is just a small 5ghz square cased chip which i have for the purpose of screwing with peoples DFS settings when there isnt a radar around.

 

[stevech]

Radar gives range, not location.
Unless multiple receivers are used and are time-synch'd to a few nSec.

 

[sfx2000]

Radar gives range, not location.
Unless multiple receivers are used and are time-synch'd to a few nSec.

.mil has had similar stuff for at least 20 years* - it's wavefront analysis on the front end - these days we see it as part of Tx Beamforming...

* my stage 1 career was .mil, then I moved to wireless