CDMA cellular triangulation??

[anandrenake]

Hi All,

I dont know how GSM, CDMA networks work...

I wanted to know a few things,

- Is cellular triangulation possible in CDMA?
- What information is required to be provided by the operator for such an application?
- Can such an application be developed in Mobile Java or Symbian C++?
Any pointers are greatly appreciated.

I am not a telecom engineer, so i dont know this...

Please help.

Thanks!

--Anand.

[petrib]

On any cellular network, the network operator can locate which cell (base station) the phone is connected to.

The network operator can also detect which other cells/base stations "see" the phone (which tends to stay connected to the one with the strongest signal).

The network operator also knows exactly where each base station is physically, what kind of antenna it has, where it is directed, what kind of delays and other signal timing is going on between the phone and the base station, etc.

With all this information and some math the network operator can approximate the relative position of the phone (not simple triangulation, exactly, but anyway).

The theory of what information is needed and how it can be used to calculate the approximate location is the same (some details vary from network technology to another).

The details of how to get that information from network elements (network devices/servers and their software) varies and depends what and whose network equipment is used.

Now, there is no way that a phone (an application running on on the phone) can have direct access to such information (and no network operator makes all such data available directly either).

However, a network operator can - if they want to - set up a service that will give the phone's position (to the phone - or an application on it - itself, or another phone or other system).

In some countries (like in the US) there are regulations that define how such information/service must be made available to officials in charge of police, firefighting, emergency rescue services, etc.

The operator can also offer (usually a commercial, fee-based) location based service (LBS) which then can be utilized by applications using APIs to request location info or other details (such as location of nearby services like restaurants or whatever), local weather, etc.

The point is, you can develop an application to request such info from the operator (in Java or C++), but if the operator does not support such a service (their own or standards based), there is no way for you to get and use the location info.

Without the operator's support you can, at most, just get the base station's unique ID (the so called cell ID), but the distance from that cell can be anything from a few meters to, say 20-30 kilometers (10-15 miles). At least you can from C++ on a Symbian OS based phone (but not necessarily from Java; it'll depend on the phone).

Then there is satellite navigation (GPS, Global Positioning System - and in the future the European Galileo system, I suppose) devices that will give you the exact location (through a serial communications based interface, via cable connectivity or Bluetooth to an external GPS receiver, or from a built-in GPS receiver, if the phone has one; very few do).

[alexis_ypy]

hi im working in a location project, im looking a way to get the information of the received signal strength from neighborhood cell(are needed at least 3 of them to make a triangulation) in a gsm network, could someone give a way to get this iformation from the sim card...thanks.

[petrib]

That information is not on the SIM card (it comes from the radio network), and that information is not available for/from Java (J2ME) applications (MIDlets), either.