All about location tracking, Part I

There are a number of technical methods of wirelessly tracking down people, equipment, and goods. What applications require location capabilities, what are the various methods of wireless location tracking to support them, and how do they work?

Let’s start with the applications. Here are a few things you might want to do with wireless location information:

* Find an emergency (911) cellular or 802.11 telephone caller.

* Find wireless devices that are unauthorized or otherwise might pose a security threat.

* Troubleshoot sources of wireless network interference.

* Conduct a WLAN site survey.

* Locate assets and equipment that have been stolen or misplaced.

* Speed and enhance a workflow process, such as the shipment of goods.

* Determine a colleague’s “presence,” or availability status, based on location.

Depending on the application, there will be different requirements for the precision of the location measurement and its degree of accuracy. For example, it might be “close enough” to know that a person or object is on a certain floor of a building (degree of precision) and for that measurement to be successfully calculated 99% of the time (degree of accuracy). The general whereabouts of a person might be sufficient for the presence application, for example. In other cases, greater precision may be needed with greater accuracy, as in the case of a 911 caller.

There are several algorithmic approaches to location tracking for use in these applications, and they have various degrees of precision and accuracy. Among them:

* Trilateration and its cousin, triangulation.

* Nearest sensor.

* Time distance of arrival (TDOA)

* Received signal strength (RSS)

* RF fingerprinting.

* GPS.

I’ll take a look under the hood at the basics of these algorithms next time.