Forget GPS, Hello WPS

No France writes "A company known as skyhook wireless has announced the commercial availability of its Wi-Fi Positioning System, or WPS. The company has compiled a database of every wireless access point it can find in a given city. When a mobile user running th Skyhook client is in a recorded area, their position is calculated by selecting the surrounding signals and comparing them to the reference database. Currently there are 25 US cities mapped, including New York City, Boston, Chicago, Los Angeles and San Francisco. Apparently this device is accurate to within 20-40 meters, though one has to wonder how well it deals with people moving their wireless access points."

The Positioning Sledgehammer

[Theo de Raabt]

All this effort to develop technology to determine your location is great if the reason for finding your location is because you're lost. But, otherwise, it seems like another case of the technology industry developing a new market for devices of questionable usage. Throw legitimate privacy issues into the mix - generally in the US at least and certainly elsewhere - the thought of some anonymous entity determining my location is positively horrifying. I can't help but think that this is one of those situations wherein the instrument precedes any of the truly challenging work of determining sensible, useful applications. (If one more dull-headed marketing guru uses the example of Starbucks ringing a phone as I walk by..) Why is it so difficult to simply self-identify my location rather than relying on the sketchy availability of GPS satellites or databases of WiFi APs and doing all that trigonometry. Here I am standing at 44th and Broadway, based on my profile and previous activities, give me some insights into other activities in the area? Or, are any of my friends within 6 blocks of me? PDPal was a project that provided a map and allowed you to target your location - easy-peasy. Dodgeball goes a light year beyond this, using technology that nearly everyone has in their pocket - a cell phone. No GPS, no WiFi positioning hacks, just a cell phone SMS. Is it because discovering application proves so difficult that the cart, burdened with gizmos, leads the applications cart?

Re:but there's really no point!

[JanneM]

Cities are the one place a positioning system is useless, so why develop it there?

You haven't tried to find a specific place in Tokyo or Osaka, have you?

Having a Gps is a life saver. You look up the place you want to go to on an online map, get the coordinates, and you're set. Without it, it's just too easy to miss the right building, mistake streets for each other or get lost in many other creative ways.

You could argue the other way round (and just as stupidly) - since there's one single highway or road in the entire area, why would you need a Gps to know which one you're on?

20-40 meters?

[Jurisenpai]

Don't these people realize how accurate GPS positioning has become?

MGIS-grade equipment [trimble.com] can now give positions with sub-foot ( 30cm) postprocessed accuracy. Survey-grade equipment can get within 5-10 cm.

As neat as WPS sounds, I don't think that anyone will be giving up GPS soon if WPS can't get any more accurate than 20-40 meters.

Re:Been there, done that!

[Myself]

Strange how the world turns, I just mentioned PlaceLab to a friend before loading Slashdot. Spooky!

PlaceLab's big advantage is the ability to use multiple sources. Wardriving data is just one potential input. If you have a GPS receiver and a wi-fi card and a CDMA phone all connected, it'll use whichever is giving the most trustworthy results. So you can move smoothly between urban, rural, and indoor environments.

What absolutely makes me giggle is this: "Morgan adds that GPS typically only locates things within a few hundred meters, whereas the Wi-Fi location system can get within 20 to 40 meters of an object."

Re:Been there, done that!

[Anonymous Coward]

Actually, having been part of the PlaceLab research team, I can confirm that "WPS" can be far more accurate than GPS. Consider that GPS is a single sample, and PlaceLab is a particle filter system which leverages many thousands of correlated samples with extra inputs such as relative signal strength.

Re:20-40 meters?

[Bastian]

Yeah, but most GPS equipment of that grade falls into the "If you have to ask how much it costs, you can't afford it" price range.

The system I work with can do sub-meter, sub centimeter with post-process. It retails for ~$40,000 plus a couple thou for a DGPS subscription and a few hundred to a couple thou for the DMI (odometer) equipment. And its precision falls off sharply (to as bad as 5 meters) in metropolitan areas where you get the GPS signal getting blocked by and bouncing off of tall buildings.

My guess would be that this system is sort of the opposite - a relatively cheap solution that works well when you don't need incredible accuracy , and it probably works best in dense urban areas where GPS tends to perform the worst.

That said, I'm not entirely sure how big their market is, because I imagine most people that need positioning equipment and work exclusively in areas with good wireless coverage are probably the type of customers who can afford expensive GPS equipment.

Not useful for typical GPS uses, but...

[SnprBoB86]

20-40 ft? This is totally useless for street navigation, surveying, etc.

What this is useful for is grander scale positioning without the need for a GPS device built into a portable device.

For example, timezones are far larger than 20-40ft. Laptops could be configured to automatically adjust the timezone setting to match the closest access points, no GPS device needed. A weather monitor utility could always automatically show the local weather. A star map could be configured to show the local sky. I'm sure many people can think of others.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Old news, with GSM this has been possible for ages

[Anonymous Coward]

Hi, I'm working with GPS tracking and have just finished one of the worlds largest online tracking of a sail reagatta using GPS/GPRS devices. (watski.watland.net). Earlier I have worked with various other systems for tracking, one of them using the distance from a GSM antenna as the measurement. Every base station(antenna) keeps a log of wich GSM phones are in the area and the strength of the signal, if you cross reference this with other base stations you get a pretty accurate measure of the position, but still there is a huge difference between this and GPS. It is pretty hard to get the accurancy lower than 50 meters (you probably wouldn't navigate your car after this...)

So, what I try to say, is after several years of working with various technologies, it is hard to match GPS on accuracy, then there is reliability and different service providers and so on...

Re:Open Source DGPS?

[DigitalRaptor]

I hadn't looked into this for a while, and it looks like some work has been done on it.

Several open source programs / projects are listed here [edu-observatory.org].

I haven't tried whether they work the way I want them to, or whether they provide the accuracy I crave... :}

Re:but there's really no point!

[mrchaotica]

GPS is useful in the city... if you want your computer to know where you are. Imagine being able to broadcast "I am [here]" to your friends (and have them reciprocate) so that your computer tells you when you happen to be in the same place and you can meet.

Imagine being able to enter meetings in your PIM software by saying to someone "Let's meet here tomorrow at five" and having the computer know where "here" is (it would also know who you're talking to, using facial recognition, but that's a different topic...).

Imagine your computer reminding you of work-related tasks as you walk into the office, and home-related ones when you arrive at home.

Imagine walking into a place you've never been, and having your computer automatically display useful information about it.

Granted, all these scenarios depend on technology beyond what's described here (namely, wearable computers), but even so GPS (and WPS, for areas such as inside large buildings where the GPS signal can't reach) is (or will be) more useful than you think.

Re:Interesting. . . .

[Dufffader]

But for typical outdoor GPS usage, depending on AGPS (Augmented GPS/Assisted GPS, etc) is a little redundant. You might as well stick to pure GPS for navigation.

What gets interesting is that AGPS is supposed to provide positioning indoors too, or in areas where GPS don't work so well. In a densely urban areas (think downtown NYC), acquiring the minimum 3 satellites for triangulation is not so easy. This is where using CellIDs and timing information from cellphone infrastructure to get your position is useful.

Now the question is... why isn't there a device to use both GPS and cell info to provide positioning info everywhere?

Skyhook?

[kingofalaska]

That is a mean trick played on newbies in the Army, at least in my first Air Assault unit. An old-timer says "go over to supply and get a skyhook, and some frequency grease for the antenna." He has a rational sounding explanation that the skyhook is the thing under the helo that the slings hook into. The newbie goes over to supply, and the seargent, playing along, sends him to someplace else. Everyone passes the poor newbie around, as long as the game can play.

On a more serious note, this sounds suspiciously like a project I worked on years ago, only this one is not as deep. Or nearly as accurate.

KoA

Alaska men should hit the trail for breasts [blogspot.com]

They got it backwards

[Jahz]

This service is interesting, but not very useful. How often are you using a wireless connection but you dont know where you are?

It reminds me of a project a friend of mine was working on earlier in the year. The college of computer science here at my university in Boston has a brand-spanking new building with cisco wireless routers built in (through all 15 or so floors). My friend was working on using these routers to triangulate the position of all of the wireless users.

This was accomplished by maticulously mapping the average signal strength of each router at various distances (1 foot, 2 feet, etc...). Since all the routers overlap a bit (as they should), extrapolating the position is not that hard. You just need a minimum of 3 routers to see any user. The more routers seeing the user, the more accurate the location. Its strikingly similiar to how the epicenter of an earthquakes is determined.

The authentication server behind the wireless network could then deny access to connections outside the building. The aim was to stop leechers from the nearby dorms and apartments, while still providing free authentication-less access (http only without authenticating) to the inside of the building.

Anyway I need to check up and see how that project is going. It was progressing well last time I checked. I think network security is a far better application for WPS.

What about RPS?

[scorp1us]

Can't you triangulate from FM radio station signal strength?

It woud have the following advangates:
Way smaller database
Way more coverage

It should be easy to do with the adevnt of software radio.

The only down side, is that you wouldn't need this company anymore!