Comments on: The three deadly sins of GPS

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By: Massimo Allegra

Massimo Allegra — Thu, 23 Oct 2008 20:21:49 +0000

Ciao Manlio, presumo tu sia mio cugino, io sono Massimo figlio di zio Piero.
Se sei realmente tu mi farebbe veramente piacere scambiare due chiacchiere, anche se solo via email.
Un abbraccio
Massimo Allegra

By: PE HUB » Blog Archive

PE HUB » Blog Archive — Wed, 03 Sep 2008 00:49:31 +0000

[...] * 3 Deadly Sins of GPS [...]

By: xiaodi

xiaodi — Wed, 09 Jul 2008 07:03:14 +0000

I completely agree with Anon imous. The 50m accuracy is the theoritical best the WLS model can achieve based on the statistical nature of the model and the PSD database (20m by 20m grid resolution). It maybe cheap to deploy (pure software based), but it is very expensive to maintain. You need to constantly remeasure and calibrate the PSD database. Based on my experience of the WLS, it accuracy is around 200m- 1000m.

By: Marty Feuerstein

Marty Feuerstein — Fri, 04 Jul 2008 04:46:15 +0000

The previous post from “Anon imous” brings to mind the fact that every location technology has pros and cons. That's why hybrid approaches combining different technologies are so powerful. GPS and A-GPS are wonderful technologies and in open-sky conditions, their accuracy is hard to beat. But for all practical purposes GPS/A-GPS doesn't work indoors, where much of the wireless usage is concentrated these days. That creates the need for complementary technologies to drive location coverage indoors and into urban canyons. In those challenging areas, other technologies can and do perform better than GPS/A-GPS — those are exactly the areas where network-based approaches like Polaris's work best because the cellular network base station densities are high. Inertial Navigation Systems (INS) and Dead Reckoning (DR) are technologies that can be used in high-end devices or in-vehicle navigation systems, but the cost, size and battery drain prohibit their mass adoption on cell phones, and more importantly they don't solve the indoor problem where even $1000+ INS/DR systems don't perform well.

To correct some misunderstandings in that post, the Polaris system does work for locating CDMA terminals, whether they are using UMTS/WCDMA or CDMA2000. The CDMA measurements used for location are from pilot control channels, which are not power controlled (they are broadcast at constant transmit power). The claimed 50 meter accuracy at 67th percentile for urban environments comes from multiple independent blind tests conducted by large wireless service providers in places like New York, San Francisco, Tokyo, London and Toronto.

By: Anon imous

Anon imous — Sat, 28 Jun 2008 02:44:00 +0000

The Polaris Wireless solution has several drawbacks including poor accuracy which can only be as good as the database which in turn depends on continuous data collection and calibration and also has problems with locating power controlled CDMA based terminals. In short, the accuracy will never come close to what AGPS can provide. GPS companies are increasingly adopting INS and DR techniques for uninterrupted location in urban areas. The 50m claim here is simply what you would expect from the CEO based on performance at select testbeds. In reality, the accuracy is of the order of several hundred meters and cannot be relied on for navigation purposes. Indoor positioning has been talked about for several years now and would be a nightmare to implement given the need to create a database that includes signal strength vectors from every floor at extremely small grid spacing. In short, WLS is good for small carriers that are looking for cheap software based solutions but can never hope to upsatge or complement GPS and AGPS solutions.

By: Location buzz continues: Nokia buys Plazes, Verizon backs Loopt & NIW » VentureBeat

Mon, 23 Jun 2008 19:00:13 +0000

[...] Various writers have recently opined at VentureBeat about location-based services (here and here). In fact, at this point, it may be [...]

By: shrirang

shrirang — Mon, 23 Jun 2008 14:26:57 +0000

Great Article by Manlio on LBS. I guess the important part is to commercialize it, esp in areas where there is no mandate by the government to have Location determined.

Local Coupons probably is very well suited for commercialization. Buddy finder has had a hype around it, but will have to wait and see. So cellfire and polaris solutions together can become a good combo.

By: 3 Below » The three deadly sins of GPS

3 Below » The three deadly sins of GPS — Mon, 23 Jun 2008 04:40:35 +0000

[...] The three deadly sins of GPS In the article below, Polaris Wireless Chief Executive Manlio Allegra … 3. Throwing Satellites at the Problem [...]

By: Andrew Grill

Andrew Grill — Sat, 21 Jun 2008 23:34:41 +0000

Perhaps the location battle is already over.

See http://www.andrewgrill.com/blog/index.php/2008/...

where I pose the question Has Google won the location battle already?

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best wifi mobile phones — Sat, 21 Jun 2008 10:59:40 +0000

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By: Andrew Graham

Andrew Graham — Sat, 21 Jun 2008 01:07:42 +0000

As an experienced LBS developer with aGPS application deployments onVerizon Wireless, Sprint, Alltel and others we are seeing faster initial acquisitions and associated consumer satisfaction than those quoted in the article (typically 5 – 20 secs).

It's true that unfiltered aGPS readings suffer from signal reflection in urban settings and look like a scatter plot even in ideal conditions.

However, we take MS based pings every 2-5 seconds to build accurate path traces (running, walking, cycling) with data conditioning that produces results within +/- 2% of actual. Here's an example from the NY Marathon.

http://bimactive.com/ba/ui/route_detail.php?f_r...

The biggest issue I see is with building penetration where hybrid approaches may help. References to aGPS being “overhyped” are a bit of a mischaracterization based on our experience with accuracy sensitive applications and the user experience of subscribing consumers.

Andy

By: Lewis Gersh

Lewis Gersh — Fri, 20 Jun 2008 22:17:47 +0000

Interesting article and points on strengths and weaknesses with LBS. At our fund, we have found that from and advertising and transaction processing services perspective, the best results so far are using coupons to area locations with a call to action. Getting to within a few blocks is usually good enough, especially if you are tying to time of day and typical user activity based on location. It' s all about scaling volume, and the highest concentrations of users in densely populated areas are critical (urban home or work, and school). If the application utilizing a LBS functionality has a consumer facing Web presence, which is often the case, the consumer's registration information can close the gap to “back up” the several block area with their actual address and provide additional value as to their psychographic profile of being at home, work or school. This won't solve for a consumer “on the go”, which is a whole other market and very much day-of-the-week dependent – consumers during the week spend most of their “purchasing” time in and around the same exact locations; weekends are much more on-the-go LBS driven without a back up of Web site registration to utilize.

By: James Geshwiler

James Geshwiler — Fri, 20 Jun 2008 15:49:03 +0000

Generally a good article aside from this being a white paper for Polaris. However, the importance of accuracy and precision depend on the application. For example, accuracy to a few meters may be irrelevant for metr0-targeted advertising and may be all that's necessary because there isn't ad inventory block-by-block. Sure, you could give someone a coupon for a store they are standing next to, but can you? Also there's a cost-benefit trade off for any infrastructure. Skyhook Wireless (mentioned above and in which I am an investor) has extremely low infrastructure costs because the public provides the beacons. At the other extreme, satellites can cost billions. Again, the investment depends on the application. (And yes, se419's comment is correct not only does one not need as strong a signal for Skyhook's technology to work but the device doesn't have to log on to the wifi network either….)

By: se419

se419 — Fri, 20 Jun 2008 13:33:05 +0000

Polaris' solution to geolocation may be good, but at least some of the claims Manlio uses to deride his competition may be inaccurate and misleading.

Regarding WiFi positioning and the service Skyhook provides, Manlio discounts coverage and accuracy based on the following statements:
“How many times have you tried to log onto the Internet via a public WiFi network and couldn’t receive a strong signal? How many times have you gone into a building and couldn’t even get a WiFi signal?”

My understanding of Skyhook's technology and service is that it is not limited to what you see when you try to connect your laptop to a hot spot. Manlio does not take into account that technologies used to sniff WiFi signals can divine much information from signals too weak for your laptop to deem relevant for display. They also use router mac addresses and don't need to rely on access point names for recognition.

For a little more on how WiFi positioning works there's a video of Skyhook's Ryan Sarver at the following link:
http://www.endpointenvironmental.com/W2MSN_meet...