Location-Based Services Realize Benefits

By Jim Geier

The combination of wireless networking and a location-based service (LBS) offers some very interesting applications. LBS technologies allow programmers to capture the location of a particular user and integrate the position information into a wide variety of solutions. Let's look at how these applications offer value, and what technical options you have when implementing them.

Pushing Local Information Increases Business

Companies often have local information that is beneficial for users to have, especially when users are residing within specific areas. If a user's position is known, a central server can then send valuable information to the user based on that location. As the user moves into different areas, the information sent to the user can then change accordingly.

Recently, I was part of a project deploying a wireless LAN in a very large airport to offer public wireless access to travelers. In this case, the airport found significant business opportunities by having the ability to push local advertisements to their wireless service subscribers. For example, a traveler waiting for a flight and browsing the Internet would see an advertisement for a nearby coffee shop. This system also pushes boarding announcements and departure delays to the users as well.

Several other LBS applications drive information to users. For example, in retail environments, customers can receive location-specific coupons and product information on PDAs as they move about different areas of the store. Visitors at a museum can receive information about displays and artifacts found in different areas of the museum. I could fill several pages of these types of solutions, but these give you enough so that you can think of others.

Tracking Improves Efficiency and Security

An LBS system makes it possible for a centralized server application to track users and assets. For example, a user's PDA can continuously provide position updates. Universities are very interested in this form of LBS. Areas such as classrooms can be places where a school can block access to the Internet and the ability for students to use chat to share test answers. Of course, the more intelligent students could still use an ad hoc form of wireless LAN connectivity for communicating with their neighbors!

A couple months ago, I visited a labor-and-delivery unit of a hospital. Immediately after a baby is born, the hospital staff attaches a small radio frequency identification (RF/ID) tracking device to the baby. This device is very difficult to remove, and sensors within that area of the hospital track the location of the baby. If anyone moves the baby outside an invisible perimeter (which is just before entering the exit areas of the labor-and-delivery unit), an alarm goes off and the system automatically secures all relevant exits. This makes it very difficult for anyone to steal babies, which happens more often than you'd think in some hospitals.

Even without the use of central server, an LBS system makes sense for tracking applications. In this somewhat peer-to-peer form of LBS, users exploit the location of other users to make better decisions. For example, emergency crews responding to natural disasters and terrorist attacks can keep abreast of each other's positions to effectively handle a situation. Each person can carry a PDA that shows the relative location of others.

Navigation Moves You in the Right Direction

It's fairly easy to tie position information to a map in order to offer navigation and directions. Many cars implement this and provide directions to specific addresses, gas stations, restaurants, and hospitals. Users discover how to proceed to a specific location in a timely manner by either receiving computer-generated voice commands, or maneuvering by referring to the car's position superimposed on a moving map.

Position-Based Monitoring Improves Analysis

When taking measurements, an LBS system reduces the amount of human input. For example, companies such as AirMagnet now have wireless LAN site survey tools that measure signal strength and other parameters, and record the results based on position. This makes performing the surveys much less tedious and more effective.

I recently performed an RF site survey of a Vivato wireless switch mounted on top of the tallest building in Dayton, Ohio. Through the use of a LBS-based analysis tool, all I had to was drive around the city streets and walk with the tool in public areas. There was no need to write down position information corresponding to specific measurements. With both position and signal strength information, the tool can easily produce a map-like graph indicating various grades of coverage.

GPS for Outdoor Solutions

A Global Positioning System (GPS) unit in a client device receives signals from at least three orbiting satellites to obtain a position. If something gets in the way of the GPS and the satellites, however, obtaining position information can be disrupted. This limits GPS mostly to outdoor areas with a clear path between the user and the sky.

GPS is an LBS technology that has been in use for years for navigation purposes. In fact, it's my primary form of navigation when flying airplanes (which I do as a hobby). In this case, GPS offers good situational awareness and helps me get to where I'm going, which is sometimes difficult when seeing things from above.

GPS cards are available in a number of form factors, making it possible to integrate position information into a variety of mobile application software. The RF site survey tools I mentioned previously make use of GPS for position information. Other applications include tracking of utility vehicles, trucks, buses, and anything else where a company can benefit by knowing their whereabouts.

WiFi a Good Platform for LBS

Some LBS approaches (such as one that Ekahau provides) utilize a WiFi (802.11) network as the basis for determining position and moving results among users and servers. In a way, this is like an indoor form of GPS, with the access points acting as satellites. At least three access points are necessary to calculate a position, and additional access points improve accuracy. Client software running on the user devices make use of access point signals to determine a relative position. However, you must calibrate the system initially against an electronic map of the facility to provide useful information.

With this approach, the server software keeps track of client device positions and also transmits this information to specific clients. This enables a variety of LBS applications, assuming that a wireless LAN is in place. The accuracy can be within a few feet, which is pretty good for most applications.

RF/ID: A Brute Force Method of LBS

RF/ID is a less sophisticated form of positioning offered by such manufacturers as WhereNet and CheckPoint. A company can place an RF/ID tag (which is a small database accessible through a RF/ID scanner) on a variety of items. With the installation of RF/ID scanners through a facility (such as a warehouse), the system can keep track of the items. When an item containing an RF/ID tag passes a scanner, the scanner retrieves the identification code and sends it to the server. The server keeps track of all items using this approach.

The accuracy of a RF/ID LBS depends on the number and placement of RF/ID scanners. For example, the system may only identify the location of an item within a few hundred feet if scanners are far apart. Some RF/ID scanners, though, can determine the exact location of an item as it passes the scanner. As a result, RF/ID LBS is very common in mail-processing plants and airport baggage transport systems where it's necessary to identify a particular item and route it a certain direction on a conveyor belt.