Location tracking is not one, single technology. Rather, it is the convergence of several technologies that can be merged to create systems that track inventory, livestock or ­vehicle fleets. Similar systems can be created to deliver location-based services to wireless devices.

Current technologies being used to create location-tracking and location-based systems include:

Geographic Information Systems (GIS) - For large-scale location-tracking systems, it is necessary to capture and store geographic information. Geographic information systems can capture, store, analyze and report geographic information.

Global Positioning System (GPS) - A constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). A GPS receiver, like the one in your mobile phone, can locate four or more of these satellites, figure out the distance to each, and deduce your location through trilateration. For trilateration to work, it must have a clear line of sight to these four or more satellites. GPS is ideal for outdoor positioning, such as surveying, farming, transportation or military use (for which it was originally designed).

Radio Frequency Identification (RFID) - Small, battery-less microchips that can be attached to consumer goods, cattle, vehicles and other objects to track their movements. RFID tags are passive and only transmit data if prompted by a reader. The reader transmits radio waves that activate the RFID tag. The tag then transmits information via a pre-determined radio frequency. This information is captured and transmitted to a central database. Among possible uses for RFID tags are a replacement for traditional UPC bar codes.

Wireless Local Area Network (WLAN) - Network of devices that connect via radio frequency, such as 802.11b. These devices pass data over radio waves and provide users with a network with a range of 70 to 300 feet (21.3 to 91.4 meters).

­ Any location tracking or location-based service system will use one or a combination of these technologies. The system requires that a node or tag be placed on the object, animal or person being tracked. For example, the GPS receiver in a cell phone or an RFID tag on a DVD can be used to track those devices with a detection system such as GPS satellites or RFID receivers.

Types of Tracking

­Companies are finding location-tracking technologies ideal for better managing inventories or fleets of vehicles. Knowing the exact location of each piece of inventory helps to control the supply chain and saves money by not losing those assets that are in transit. Companies, such as retailers, must consider how to track inventory across a wide area, either country or state, and in a smaller area, such as the warehouse or store.

Wide-Area Tracking

On a large scale, companies must track their vehicle fleets across the country or the world. GPS is the ideal tracking technology for tracking over large areas. To do this, every vehicle needs to be equipped with a GPS receiver. As the vehicle crosses the country, the GPS satellites track the truck's position. With GPS, the operator can request positioning at anytime. However, GPS is limited in smaller areas or indoors.

Local-Area and Indoor Tracking

A good example of where GPS would not be suitable for tracking items is in a warehouse or hospitals. The accuracy provided by GPS is not sufficient for such a small scale. Consider all of the medical equipment, wheelchairs, gurneys and even patients that need to be tracked. GPS is not a practical or cost-effective solution.