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Wireless Networking Hardware Science Technology

Forget GPS, Hello WPS 286

Posted by timothy
from the ded-reckoning dept.
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."
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Forget GPS, Hello WPS

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  • 20 - 40 meters? (Score:3, Insightful)

    by Anonymous Coward on Tuesday June 21, 2005 @11:54PM (#12878452)
    20 - 40 meters? Who will be forgetting GPS with that kind of crappy accuracy?
  • by cryptoz (878581) <jns@jacobsheehy.com> on Tuesday June 21, 2005 @11:57PM (#12878470) Homepage Journal
    If you're in a major city, you seriously don't need GPS or any positioning system. Look out the window of your car, ask someone, etc. GPS is needed and useful when you're NOT in the city, when you're out in the middle of nowhere or on a highway getting lost. Cities are the one place a positioning system is useless, so why develop it there?
  • by photon317 (208409) on Tuesday June 21, 2005 @11:59PM (#12878480)

    Rather than trying to maintain a static database of AP locations and signal strengths, they should just put some live wifi nodes out there with real GPS on them and track the AP map in realtime as it shifts. Or they could give free service to a select small percentage of customers in return for attaching a GPS device and helping recalibrate the map with some background software once a month or something.
  • by meatflower (830472) on Wednesday June 22, 2005 @12:17AM (#12878558)
    I honestly would expect it to be even worse.
    If this determines position by signal strength wouldn't it then be dependent on the type of antenna you were using with your WiFi card? Sometimes my signal moves around even in the same position or drops significantly lower in "dead spots". What if I'm using one of those crazy Pringles can antennas?

    "Hey! 100% signal here, I'm here, over there and...yep, that a ways too!"

    Anyhow, what an awesome idea, I mean, it's not like we have anything like this in existence, you know, that millions and millions of dollars were put in to launch satellites into orbit. No, nothing like that, nothing that has 10 feet or less accuracy. Guess we should all start usin this POS. No thanks.
  • Interesting. . . . (Score:5, Insightful)

    by Bagheera (71311) on Wednesday June 22, 2005 @12:22AM (#12878575) Homepage Journal
    . . . but I suspect ultimately of little practical value. Having done quite a bit of RF scanning on the WiFi bands in one of their listed cities (San Francisco) I've seen first hand how signals behave in that dense urban environment.

    GPS and WAAS operate on time signals and highly accurate positioning. Cell towers would be inherently more accurate since thier positions are accurately known and don't change (except under very unusual circumstances.

    WiFi nodes come up and down constantly, and their position is rarely going to be accurately known by anyone but the person who installed it - and chances are they're not telling "you" exactly where the node is.

    Given "walk around surveying" to map the nodes, it's not really a surprise they have accuracy that's no better than an early 2 channel GPS receiver.

    And, as others have pointed out, if I'm in downtown San Francisco (or any other city) I don't need my GPS to tell me I'm at 5th and Townsend. For directions there's Mapquest, Google, Yahoo Maps, etc...

    Interesting technology. But it sounds more like something a hobbiest would come up with than business.

  • Re:Oh man. (Score:5, Insightful)

    by nmb3000 (741169) <nmb3000@that-google-mail-site.com> on Wednesday June 22, 2005 @12:40AM (#12878636) Homepage Journal
    To be honest, I don't care how novel their ideas are. Using a system where position is located based on such arbitrary measurements is not only silly, but a waste of time. Not only can anyone move the access points around, but as they get shut off or more get added it will only make things worse. Also considering it can be influenced by minute things like weather and the position of the microwave in the apartment across the street make it a waste of time. You'd need to rescan it at least monthly to maintain even 20-40 feet (screw that) accuracy.

    Let's see, a near-absolute positioning system based on immobile and unchanging (or extremely slowly) data, or something based on what could probably be described as a chaotic system? Not to be a jerk about it, but "Forget GPS"? More like "Ignore WPS".
  • Re:Oh man. (Score:3, Insightful)

    by Johnny Mnemonic (176043) <mdinsmore.gmail@com> on Wednesday June 22, 2005 @12:47AM (#12878651) Homepage Journal

    Assuming people don't get swap-happy and trade access points all over the place, the reliability should be very high, too.

    Well, that would be an issue, wouldn't it? And, unlike, say, a system you own, other folks own and control these datapoints that your system depends on.

    I have to say that I regularly reconfigure my WAP becasuse, well, it's mine, and I chose to use it like a toy. I notice that a great many of my neighbors have WAPs of their own, but, not so surprisingly, I find that everytime I look the configuration is a little different--cause they're playing with theirs too.

    You know, they lose power so vanish for awhile. Or are configured for security, but then the owner decides that's too much a pain in the neck so reverts. Or buys a different brand, hoping to get better signal. Or people move away--I hear that "rentals" are common in "urban centers", which tend to attract a transient demographic. Or the mix changes for any number of other reasons.

    I hope for your sake that you guys took a snapshot and then took another 3 mos. later to determine average drift; I suspect that it'd be significant, enough that you couldn't triangulate off of it, at least.

    Really, at this stage of your product cycle you shouldn't be guessing if this is feasible; you should be able to respond to this (obvious) criticism in the strong affirmative, without the guessing you displayed. How else can I be expected to trust it? And while it may be accurate for a month or so, it'll only be updated once a year? Gee, I sure hope I'm trying to get my position at the beginning of the year rather than at the end.

    Sorry to be harsh, but really this is one of the stupider ideas I've seen posted here. You may as well give directions based on the make, model, and color of cars parked in driveways. Those don't change, much either. But over the course of a year, I guess they actually do, huh?

  • Re:20-40 meters? (Score:2, Insightful)

    by invisigoth (131518) on Wednesday June 22, 2005 @01:10AM (#12878734)
    This can solve some problems associated with standard GPS. Namely, that satellite-based GPS systems fail when structures block line-of-sight to the satellites in the sky. This can include things like tall buildings in urban areas, or underground parking garages, etc. Since WPS is purely terrestrial, it can overcome many of these problems. Of course, satellite-based GPS is still preferable if you don't have these issues.
  • Re:Oh man. (Score:4, Insightful)

    by andy jenkins (874421) on Wednesday June 22, 2005 @01:26AM (#12878787)

    Yes, but my iPaq has Wi-Fi not GPS. And the screen can show a good map.

    I could ensure I'm always carrying a GPS reciever or just a city map but you know what, I own both these and only carry them when I know I need them. Which in the case of GPS, is never.

  • Re:20-40 meters? (Score:2, Insightful)

    by wramsdel (463149) on Wednesday June 22, 2005 @01:45AM (#12878849)
    What accuracy, exactly, does GPS give you when it can't see any satellites? Skyhook isn't trying to sell this as a replacement for GPS, rather as a complementary technology. In fact, they even have a nice USA Today-style graph on their "Technology" page showing that the overlap between GPS and WPS is fairly small. What marketing person in the world would look at this graph and say "Let's position our technology as a replacement for GPS!". That's not even Internet-bubble thinking.

    That being said, keep in mind that the goal is locational awareness. Any information that you can feed into that equation has the potential to be helpful. It can also be harmful if used in an inappropriate manner. Take, for example, the case of an access point which has been moved. Your device could say "I see this access point, so I must be in some radius of its last known location." It could also say "I see this access point, but my last good GPS fix was 75 seconds ago, and the user can't have moved that far in 75 seconds, so I'll choose to disregard that information." If you consider all the potential inputs to the "locational awareness" equation: GPS, WLAN, WiMAX, fixed Bluetooth, RFID readers, etc., it becomes clear that you can start to do some pretty cool stuff with system redundancy.
  • Re:Oh man. (Score:3, Insightful)

    by MoneyT (548795) on Wednesday June 22, 2005 @01:51AM (#12878864) Journal
    Now the real question is, how often do access points get moved or shutdown?
  • by MoralHazard (447833) on Wednesday June 22, 2005 @01:55AM (#12878872)
    20 to 40 meters of accuracy? I work with various grades of GPS and even with low accuracy gps I can get within 10 feet no problem.

    My FAVORITE kind of slashdot post to respond to is this one. It's a combination of "I'm missing the point entirely" AND "I think I'm a lot smarter than I am." All rolled up into four little sentences.

    WHY IS WPS USEFUL: Because there are a lot of urban areas where you can't get GPS signals for shit. Try New York City, for one--you're lucky if you can get two or three satellites in Manhattan, most of the time. I've spent a LOT of time trying to make GPS work in this city, and it sucks--and I know there are probably other places where the same thing happens.

    So if your GPS can't give you any kind of signal, 20-40 meters is pretty frickin' good, wouldn't you say? Sure, 2.4 and 5.8 GHz signals get attenuated by common building materials, but not so much that it throws off triangulation too badly. I can routinely do reasonbly accurate triangulations (+/- 10 meters) on access points (sort of a reverse of the WPS process) near the ground in all sorts of medium-heavy office buildings.

    Now, add in the fact that there are probably at least 10 million wireless client devices in consumer hands in the US today (a number that grows as we speak!), and compare it to the distribution of GPS receivers. Chances are, most everybody with a laptop has WiFi, but there's a lot of people that don't have GPS. Cost isn't really such an issue--there are cheap-ass USB GPS receivers all over (running on Linux, even). I think it has more to do with the fact that GPS is less of a "need-to-have-it" thing, and it's rarely built into laptops and PDAs.

    Point is: MANY more people have a WiFi receiver than have a GPS receiver, and it often works as well or better in urban areas or in buildings.

    Do you see it, now? Sorry for the snark-attack, but man, how did you not get this?
  • by anthony_dipierro (543308) on Wednesday June 22, 2005 @08:07AM (#12879747) Journal

    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.

    Wow, I've gotta really disagree here. If GPS were cheap enough, I can think of a lot of legitimate uses for it other than when I'm lost. Basically, it's useful for tracking things (where did I park my car? where did the car thief take my car?), and tracking myself (how far did I travel for business purposes in 2004? what time did I get to work yesterday?).

    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.

    If by "some anonymous entity" you mean the government or your phone company, well, they could have already done it anyway. I don't see it as horrifying. I don't think it's such a good idea, but I still have a cell phone.

    Why is it so difficult to simply self-identify my location

    Besides the fact that good voice recognition technology isn't that widespread, it'd be a big hassle to constantly identify ones location. ("OK computer, I've parked my car in section D-5. OK, now I'm arriving at work.")

    rather than relying on the sketchy availability of GPS satellites or databases of WiFi APs and doing all that trigonometry

    Sketchy availability? Availability of GPS is basically a question of "are you outside?" It doesn't work as well indoors, and that's a problem for a lot of uses we might dream up for it (tell 911 where I am), but it was built for guiding missles, not calling 911. This is one advantage that wifi access points may be able to give. Of course I'm skeptical as to how reliable such a scheme would be. It certainly will never be global like GPS. I can get a GPS reception in the middle of the pacific ocean.

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