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You have gone to Covent Garden Market in London for the first time with your wife and children and have got lost. May be these are the series of questions that come to your mind.

Where am I?
What is around me?
Where are they?
How do I get there?
Where is it?
Where was I?
What is my Orientation?

The solution to all these questions is LBS (Location Based Services). LBS helps us locate position of any object on our planet. Common uses of LBS are Navigation, Mapping, Troop deployment in military, Vehicle tracking etc. All that comes to our mind whenever we talk about LBS is Global Positioning System (GPS) but LBS is not GPS. GPS is one of the several ways LBS tracking is done. The most popular positioning methods used by LBS systems are:

Satellite Based Positioning

GPS Constellation consists of 24 satellites that orbit the earth every 12 yours. To use this GPS system all we need is GPS receiver. This receiver is tracked by 3 or more satellites and the calculations are done to get a correct position of The GPS receiver.

Cellular Network Based Positioning

In this method the service providers Network towers calculate the position of the mobile phone by calculating the position based on the signal strength from various towers. However GPS approach gives more accurate results.

Short Range Positioning

In this method the Bluetooth talks with a local server to get position.

The above approaches are taken care by the Location API implementation and finally we get latitude, longitude, altitude and precision of service.

LBS development to track a mobile user can be done in two ways - Application on mobile approach & Service Provider Webservice approach

Application on mobile approach

A J2ME or any other platform application sits on the mobile phone and calls API's to find the position. This approach has following features

• A GUI based application on your mobile phone.
• No need of any tie-up with the service provider. However service providers may charge you for access to this service.
• Target devices can only be J2ME phones or any others phones that support Symbian, Pocket PC etc.

Service Provider Web service Approach

Here your server application directly queries the service provider web service which gives the mobile user position. This approach has following features

• Major advantage of this approach is that any mobile phone can be tracked imaterial of platform, OS etc.
• This approach is not suitable for Mobile maps
• Tie-up needed with the service provider and the service providers will charge you for this service.

In this tutorial we will consider the J2ME application approach. For web service approach look at your target service provider’s documentation for more details.

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