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BlackInkBottle's Ink » Get "My Location" on mobile phone without GPS, from Google Maps

Get "My Location" on mobile phone without GPS, from Google Maps

This feature is really nice! I downloaded the latest Google Maps from my non-GPS Symbian phone, fired it and immediately "My Location" was located on the map, with acceptable and in fact praisable accuracy.

The way how it works (in theory) is no rocket science, yet it is just this one extra step that makes things so different! Small step, big changes: it's said "Fewer than 15% of the mobile phones expected to ship in 2007 have GPS capabilities".

From the same article "Google Talks Up Enhanced Mobile Google Maps And Location Services", some questions are answered:

"OTA: What technology is involved? Is this technology Google acquired?

SL: The technology was developed within Google and it uses mobile towers to approximate location. Mobile towers are placed by operators throughout an area to provide coverage for their users. Each of these towers has its own individual coverage area, usually split into three nonoverlapping sections known as "cells." These cells come with identification numbers, but no location information. Google takes geo-contextual information and associates this information with the cell at that location to develop a database of cell locations. With this information, Google uses various algorithms to approximate a user's handset location relative to the cells nearest to him or her. The accuracy of this information depends on how big an individual cell is. So areas with a denser concentration of mobile towers allow for a more accurate My Location reading. And as our database of cell locations continues to improve, so, too, will the accuracy and coverage of the My Location feature.

OTA: So does this mean that Google knows where users are when they use the My Location feature?

SL: No, it doesn't. Google Maps for mobile sends anonymous radio information back to Google servers to improve the service, but Google doesn't gather any personally identifiable information as part of the My Location feature or associate any location data with uniquely identifying data."

The answer is not crystal clear. It seems that Google Maps transmit both location information and cell information from phones that have GPS capability to construct the said database over time. When only cell information is sent by non-GPS phone, look up routine is performed to retrieve the location. In other words, GPS phones have performed surveying tasks (remember drone?)

Google eases mobile map use by locating celltowers (from Straits Times)

Visit http://www.google.com/gmm/mylocation.html?hl=en for details too.

 

Posted Nov 29 2007, 08:32 PM by blackinkbottle
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Comments

Softwaremaker wrote re: Get "My Location" on mobile phone without GPS, from Google Maps
on 11-30-2007 11:34 AM

This is really nothing new - with the onset of Location-Based Services (LBS) in the late 90s.

I suspect that this is more a telco play more than the map-provider play. Telcos have to give permissions to their co-ords of their triangulated cell-towers so any provider can determine the geo-locations and decide how they want to provide value-add services to the end-consumers.

In fact, with the triangulation technology of GSM networks, it is well-known that privacy is an issue although telcos has given assurance for many years that they will respect it.

blackinkbottle wrote re: Get "My Location" on mobile phone without GPS, from Google Maps
on 11-30-2007 3:51 PM

True, triangulation requires reading of signal strength from identifiable cell-towers and the exact coordinates of those cell-towers involved in the triangulation calculation.  In fact only telcos know their assets and such info well.

However, I think added value of google's My Location feature is that it does not rely on being given such coordinates information from telcos (ok in fact this is pure guesswork :)). They probably relied on thousands of phones that DO have GPS installed. When such devices send information, both cell towers information and their CURRENT location is sent. When there are many phones sending from nearly everywhere, millions of surveying records could be accumulated and are being accumulated.

Algorithm could then be used work on such huge amount of records to deduce where the cell-towers POSSIBLY are. The database of cell-towers could grow in size and improve in quality over time.

This is the small step that I consider valuable. Of course, privacy might be a issue, but if it is claimed anonymous, I might have to believe it.

Somehow, the idea reaps the economy of scales of distributed computing, just in LTA's traffic condition system that constructs the loading information based on the info sent by all the roaming taxies.

sidyk wrote re: Get "My Location" on mobile phone without GPS, from Google Maps
on 12-12-2007 4:08 PM

Nice post. heres my comments:

Pls note that such locality positioning is fully dependent on the telco's cellular infrastructure and telco's willingness to reveal their subscriber's mobile location and at an affordable pricing. Thats the major drawback...

nevertheless, Network dependent positioning have some good advantage over GPS:

- able to work almost just as good indoors, whereas GPS signals deteriorate to almost nil when you enter a building, underground or a road tunnel.

- easier to build more responsive LBS and other apps since locality data is available on the network; no need to fetch the coordinates from the client GPS mobile phone. (enabling Push rather than pull)

then again network-based flipside (disadvantages):

- accuracy is dependent on the density and capabilities of the telco's cellular topology. More dense  the cellular base stations, the smaller the area of coverage of each base station hence more accurate the location. On the other hand, if the telco uses tall antennas to cover large radius of area, accuracy suffers

there are techniques such as Enhanced-observed Time Difference  (EOTD), Time Difference of Arrival (TDOA), Angle of arrival (AOA) to help with the accuracy but nothing as close to GPS in terms of long-term reliablity.

theres more to this area of study, in fact there is a whole bunch of academic researchers in various universities working on it. Give it a few more years, and I believe the technologies will mature and LBS will truly flourish.....

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