More About Location-Based Services

In the September 5 issue of Mobile & Wireless UPDATE, I provided an overview of the Location-Based Services (LBS) industry and shared some application ideas. Many readers requested more information about the topic, so today I continue the discussion by looking at the advantages of LBS compared with traditional Global Positioning Services (GPS). I also delve more deeply into how LBS applications work.

LBS-aware applications show huge potential for enterprise solutions—for example, dispatching courier requests for package pickup to the driver closest to the pickup location. To utilize LBS information, an LBS-aware application would make a request to the wireless carrier network. The wireless carrier would then use one of several methods to determine a user's location on the wireless network and return the latitude and longitude coordinates to the LBS-aware application.

LBS location methods fall into three primary categories: network overlay, handset enhanced, and enhanced cell ID. The methods that carriers implement depend on levels of accuracy required, network technology, and existing infrastructure.

  1. Network overlay—Involves positioning technologies such as Time of Arrival (TOA), which accomplishes triangulation of a user's position based on the speed at which a user is moving away from or toward various cellular towers. This technology is primarily for legacy handset support and provides accuracy within about 300 meters.
  2. Handset enhanced—Involves positioning technologies such as Enhanced Observed Time Difference (E-OTD), which requires additional handset capabilities (e.g., device processing) to locate a user's position based on triangulation. Handset-enhanced location methods provide higher accuracy than network-overlay methods, providing accuracy within about 50 to 100 meters.
  3. Enhanced cell ID—Provides methods of enhancing current cell ID technologies to improve accuracy. These enhancements include Receiver cell signal (RX) strength and provide accuracy within about 1000 meters. Enhanced cell ID is now the most commonly tested and used LBS method.

You can use these location methods to locate a user's position on a wireless network. Depending on the accuracy you require, you might choose to stick with your existing handsets or replace them with newer enhanced handsets.

The advantages of using LBS instead of traditional GPS are as follows:

  • No additional hardware required—Because LBS requests are a network service and aren't calculated on the device, wireless carriers can locate legacy cell phones. However, some of the more recent LBS triangulation technologies require new handset features.
  • Lower costs—Because LBS is a wireless network function, no additional wireless data is necessary to send location information to LBS-aware applications. However, the exact cost of making LBS requests is unknown, because wireless carriers aren't yet offering enterprise LBS services. Most likely, wireless carriers will charge for LBS services on a per-request basis.
  • Indoor usage—Unlike GPS, which requires a direct sky view to at least three satellites, LBS works indoors and in situations in which GPS doesn't work. Indoor usage makes LBS effective for mobile enterprise applications.

As I discussed last time, wireless carriers are implementing LBS solutions so that they can locate users on their networks. The Location Server at the carrier is also known as a Gateway Mobile Location Center (GMLC) or a Mobile Positioning Center. The Location Server is the software platform that provides location information. This Location Server platform implements the above-mentioned location-determination mechanisms. Most enterprises, however, won't have direct access to the Location Server; instead, carriers implement an external gateway known as the Location Enabling Server (LES). The LES connects to the Location Server and provides an external XML-based interface for application developers. Therefore, enterprise developers don't need any information about the specific and often proprietary Location Server to determine a user's location.

Several wireless carriers are piloting the LES server for third-party developer access to LBS information. As public access becomes available, I'll definitely let you know in upcoming Mobile & Wireless UPDATEs. See you next time.

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