2. I would not expect that to work very well without an IMU, but you can do some pretty remarkably good odometry using wheel rotations, vision, and/or automotive radar if you’re dead set against using an IMU.

3. I think they were measuring instantaneous Doppler and integrating to get phase. They only looked in a 1 MHz passband, and they didn’t have a very directional antenna, so they must have been acquiring something pretty narrow-band compared to the full downlink packets.

There have also been many other projects like http://wearnotch.com/

For now, External distance cameras (Kinect-like) seems to be the most accurate and usable method. Something like what these quadcopters use: https://www.youtube.com/watch?v=AiCFtmdrvHM

Sort of. Dead reckoning with accelerometers is only as good as the error correction. Accelerometers tend to gain error factor very quickly without using a form of sensor fusion such as a partnership with a magnetometer to cross reference things like yaw with.

"indoor gps" is a point of intense interest right now it seems like for in-shop marketing and other (evil) things.

GPS is accurate to within 30 cm. My old team at Apple did this for indoor positioning. The challenge was that the mag readings can be highly variable indoors & don't have enough texture outdoors. It's interesting they've managed to get it down to 10m. That could be pretty valuable when you integrate it as part of your overall SLAM algorithm & to reduce the overall power requirements. Instead of having GPS always on, primarily use mag + IMU dead reckoning. Then strobe the GPS every minute or so to get a more accurate fix (GPS signal generally can reacquire within a minute of a previous successful reading).

My knowledge of location systems only extends so far, but from what I know 3G, 4G and WiFi have not introduced anything particularly remarkable here. Wifi APs and various BSs are used as beacons (a la Skyhook), but their role doesn't extend much beyond that.

Anyway, there is still hope that 5G or some IEEE standard will make a difference here. They could perhaps provide something akin to a ground satellites, maybe at a very low frequency (to get past obstacles), or/and perhaps using UWB (helps with multipath, TOA determination). And then maybe we would have zeroish-time-to-fix, indoor-location on cheap, low-power devices.

It's possible to make good guesses, but it's a pain, and they're still guesses. (Well, they were at my level anyway)

I thought the tracking could be mostly automated between GPS (outdoor) and direction finding + dBm (indoor/canyon), but I guess not.

We have built an Indoor-Navigation-System with a POI-Editor for OSM and Route-Planning algorithms and more.

The article is disappointing, because it doesn't tell much more than you already know by reading the title. Here's the original article: https://wncg.org/research/briefs/centimeter-accurate-low-pow...

Then there is also an even greater TED Talk by Todd Humphrey: http://www.ted.com/talks/todd_humphreys_how_to_fool_a_gps

You can find more about their plans for the VR-Application here: http://radionavlab.ae.utexas.edu/videos/280-precise-augmente...

http://www.trueposition.com/about-trueposition/resource-cent...

Accuracy of 50 meters is a bit disappointing, but hopefully the technology has room to improve. It's also disappointing that they're focused on the benefits for law enforcement and carriers rather than handset makers and end users.

I'd wager there are _a lot_ more folks that that looking the problem. Its difficult to just use signal strength as this is heavily multi path dependent and time-varying as anything (e.g., moving your phone and hand around) within the environment changes.

There are results in the literature floating around that show some basic success, but nothing at all like the dreams of indoor GPS we're all hoping for. It's a fun problem space, but still in its infancy.

I worked at at an indoor location-systems startup once. The real fun part of the system was integrating wifi-based location with streaming video from fixed-mount cameras to pinpoint location even better. But let me tell your right off: wifi calibration of the sort they're talking about can be incredibly obnoxious (think "carefully rolling a laptop in a cart at a constant speed around a space, in a grid", which could easily be completed in an hour or two if you are really good at it, but might take a day or two to get right if you aren't.) Sure, this is all fine if you want to calibrate one or two indoor spaces for your automated drones, especially if you've already got APs deployed in a location-friendly mode (i.e. more around the perimeter and less around the center, with antenna orientation to match), but don't expect to see it in a corner store near you anytime soon.

Now, if you can talk about automating the calibration you'll do quite well.

Though you are right, a system depending on some entirely other phenomenon for location would be even more exciting.