Real-time location systems: Can you find me now?

Real-time location systems (RTLS) have been around for years. Retailers use these systems to track inventory, and trucking companies use them for fleet tracking. Although the two applications sound similar, the underlying RTLS technology for both applications is quite different. This article provides an introduction to real-time location technology and a description of several common applications.


Real-time location systems determine the position and location of a target. Position identifies a spot on the Earth using a

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geographic coordinate system (e.g., 32° 49' 49.7964' -- 116° 49' 9.9228"). Location refers to a certain place in the real world (e.g., Boston's North End). RTLSs determine position and location using a variety of technology, as described below:

  • RFID: Radio frequency identification (RFID) systems consist of low-cost electronic tags that can be interrogated by electronic readers. In most RFID environments, the primary purpose of the system is to identify the tagged items (e.g., inventory tracking). These items may be constantly in transit, such as on a manufacturing line, or they may be tracked as they are moved from a retailer's shelf. Most RFID readers and tags operate only at very close range, offering proximity location within inches or at most a few feet.
  • Wireless LAN: A WLAN with one or more location servers has the ability to locate WLAN-enabled devices anywhere within the facility or campus. Any device that is communicating with the WLAN has the potential to be located in real time using the WLAN system. These WLAN location capabilities have been extended to locate individual users on the network, including WLAN phones for Enhanced 911 (E911) services.
  • Mobile cellular: Mobile cellular phone systems have incorporated location-detection and tracking mechanisms, such as Time Difference of Arrival (TDOA) and Triangulation. These mechanisms enable mobile operators to offer location-based services, such as fleet tracking, and enable first responders to dispatch emergency personnel to the appropriate location.
  • Global positioning system (GPS): GPS receivers rely upon a constellation of satellites circling the world. Unfortunately, the signals from the GPS satellites do not generally penetrate to the interiors of buildings and can be blocked by tall buildings in dense urban areas. This limits the use of GPS to outdoor environments where there is a clear line of sight to at least three of the satellites.
  • IP geolocation: The most established RTLS is not based on wireless networking technology at all but relies on Internet Protocol (IP) addresses to provide geolocation information. Geolocation provides the ability to route users to different websites according to the presumed location of the origination IP address. This capability is often utilized to route the user to data centers that are closer to him in hopes of providing better performance and faster response times.


Location applications are quite varied. The list below highlights some of the more common applications.

  • Fleet tracking: Fleet-tracking systems utilizing GPS technology have been available for many years. These systems enable an enterprise to analyze fleet activities (e.g., trucking) in real time and include the ability to track vehicle location and speed, optimize routes, schedule jobs, aid navigation, and analyze driver efficiency.
  • Navigation: In their simplest form, navigation services provide directions for how to get from Point A to Point B. Navigation services from companies such as Garmin and TomTom rely on ever-changing map databases from companies such as Tele Atlas and NAVTEQ to translate GPS-supplied position information into user-friendly location information. In October 2007, Nokia agreed to acquire NAVTEQ for $8.1 billion. The combination of GPS, mapping, and mobile cellular technology will enable mobile devices to offer new navigation services.
  • Inventory and asset tracking: RFID technologies are widely used for asset and inventory tracking. RFID readers are distributed throughout the enterprise in order to communicate wirelessly with the RFID tag on the target. The wireless readers must be connected to a network to allow real-time communication with a management console. Placing RFID readers at specific "chokepoints" will allow the tracking of inventory as it enters and leaves a facility and will enable an alarm to be activated when tagged items are removed from authorized areas.
  • Personnel tracking: The underlying technology for personnel tracking varies according to whether personnel reside inside the enterprise or are fieldworkers located many miles away. Fieldworker solutions typically rely on GPS technology embedded in mobile phones. The drawback of such services is that they are limited to the coverage area of the mobile operator. In contrast, in-building personnel tracking systems often use RFID technology. RFID-enabled badges, and RFID readers at specific locations, can provide details on when personnel are within range of a given location.
  • Network security: One of the more interesting applications of location detection is the ability to enable logical "boundary" enforcement. The use of Wi-Fi Protected Access (WPA) can prevent an eavesdropper from decoding transmissions, but it also has the advantage of being able to limit the physical area from which a user can connect. By creating logical boundaries, the enterprise can restrict access based on the user's location.


For many enterprises, the biggest issue with RTLS is privacy. Employees may be concerned that their manager is tracking their whereabouts throughout the day. Other important questions include: How will the location information be used? Who has access to location information? When is the information legally discoverable? How long will location information be stored? Enterprises must create and enforce privacy policies that protect employee and employer privacy.


Real-time location systems are poised to make a significant impact on the enterprise. Advances in location technology and expanding enterprise wireless applications will drive the deployment of next-generation RTLS throughout the enterprise, but enterprises must create privacy policies and establish processes that ensure policy adherence.


About the author: Paul DeBeasi is a senior analyst at the Burton Group and has more than 25 years of experience in the networking industry. Before joining the Burton Group, Paul founded ClearChoice Advisors, a wireless consulting firm, and was the VP of product marketing at Legra Systems, a wireless-switch innovator. Prior to Legra, he was the VP of product marketing at startups IPHighway and ONEX Communications and was also the frame relay product line manager for Cascade Communications. Paul began his career developing networking systems as a senior engineer at Bell Laboratories, Prime Computer and Chipcom Corp. He holds a BS degree in systems engineering from Boston University and a master of engineering degree in electrical engineering from Cornell University.

DeBeasi is a well-known conference speaker and has spoken at many events, among them Interop, Next Generation Networks, Wi-Fi Planet and Internet Telephony.

This was first published in September 2008

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