Home | Business News | Browse by Publication | J | Java Developer's Journal

The location API: simplify access to mobile positioning methods.

Article Excerpt
The Location API (JSR 179) was accepted by the Executive Committee for Micro Edition of the Java Community Process in June 2003. It provides an abstract interface for access to location-based information, such as the current coordinates of the mobile terminal independent from the underlying positioning method used.

Mobile Positioning 101

Mobile positioning in general is the process of determining the location of a mobile terminal; the result of this process is the mobile location, which is the current location in terms of coordinates of the mobile terminal. The mobile location can be more or less accurate, depending on the mobile positioning method used.

The large number of existing methods that can be used for mobile positioning can be divided into two broad categories: network-based and handset-based. The first category, network-based positioning, is made up of many methods that reach from relatively simple CO0 (cell of origin) methods to more complex methods like TDOA (Time Difference of Arrival). The latter category, the handset-based positioning methods, allows locating the terminal without the help of the mobile communication network (for example, the GSM or CDMA network). GPS--the Global Positioning System--is the most prominent member of that category.

Besides those two categories, there are also hybrid methods that unite network-based and handset-based methods. AGPS (Assisted GPS) is one, where you try to speed up the initialization time of the GPS receiver by using information coming from the mobile network.

The following sections explain the most common positioning methods in more detail. Figure 1 provides an overview of the described methods.

[FIGURE 1 OMITTED]

Handset-Based Methods

* Global Positioning System(GPS):This system was developed by the U.S. Department of Defense and is still maintained by them. Originally developed only for the military, today this positioning system is widely used by civilians. The system is based on signals that are transmitted from 24 satellites that GPS receivers on earth use to calculate the current location. Each GPS receiver needs to be in contact with four satellites at the same time to be able to determine the user's longitude,...

View this article FREE - Now for a Limited Time, try Goliath Business News
Free for 3 Days!