The use of wireless technologies for location and tracking purposes can trace its roots back about 80 years to...
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the invention of radar, an essential element of many current commercial and military systems. While radar involves bouncing numerous radio pulses off an object and sampling the energy reflected back to determine the location and heading of said object, another valuable technique uses radio transmissions from a particular source to do the same. GPS and onboard transponders used to track aircraft, for example, work in this way.
Using Wi-Fi for location and tracking purposes has been around for many years, and the more recent development of using Bluetooth Low Energy, or BLE beacons, for similar deployments has served to increase interest in these important technologies. Want to know where key people and equipment might be in mission-critical settings, like healthcare? This is how it's done. These technologies can help find residents wandering off in assisted-living facilities, or find lost kids in theme parks. They can help people locate particular items in a superstore or find their way through stadiums, airports or convention centers. The list goes on.
The topic of location-based services is of great interest for many organizations seeking to personalize user experiences in a particular area. And, as one might guess, the network plays a critical role in every one of these applications. Imagine receiving customized information in a museum while standing in front of a particular exhibit -- we're limited only by our imaginations.
Using signal strength for tracking
The most common technique applied in the wireless LAN and Bluetooth space uses signal strength. The basic idea is to take advantage of the fact that radio waves become weaker the farther they go, declining with the square of the distance between the endpoints of a given link. Because radio waves bounce around within an indoor environment and lose significant energy when passing through walls or ceilings, becoming artificially weaker, any given sample or radio energy can be an invalid indication of range.
But if one takes enough samples and rejects any anomalous results, it is possible to locate and track a given station in real time, often with good accuracy. For example, in many cases, results have been achieved using unmodified Wi-Fi clients and infrastructure of approximately 1 square meter, with the required additional effort limited to adding an access point (AP) or two, or a one-time calibration via application software.
BLE beacons work in a similar fashion, providing a near, medium or far indication of the distance between a given station and the beacon. Since a single beacon can provide only a rough distance to a station somewhere in a circle around it -- indicating presence, but not actual location -- two or more BLE beacons can be applied simultaneously to provide a more specific location indication. Note that both the Wi-Fi and the Bluetooth options described here require a network connection in order to map the assumed location to the physical space where the beacon is installed -- commonly via an imported facility floorplan. BLE beacons simply transmit a unique ID that must be looked up in a database, again via a network connection -- and, perhaps ironically, over a Wi-Fi connection that might also be used for location and tracking.
Comparing BLE beacons and Wi-Fi tracking
When comparing BLE beacons and Wi-Fi tracking, which option is better? Well, the Wi-Fi approach can be low in cost, even free, as some AP vendors provide credible location options at no additional charge. But it could take additional APs to get sufficient accuracy. The BLE alternative may involve literally thousands of beacons, which can get costly and even unwieldy from a management and operations perspective -- each beacon must be installed, noted in a database and have its batteries changed occasionally.
However, the recent development of virtual beacon technology -- incarnated as an AP-like device, or even integrated into Wi-Fi APs -- changes the economics and logistics of BLE-based location and tracking dramatically. It's even possible to move a virtual beacon via software to improve coverage or the quality of results. And, of course, both Wi-Fi and BLE options can work together when needed.
But perhaps the most interesting recent development in the location and tracking field is the work now underway on a new standard, IEEE 802.11az. This enhancement will likely use a form of round-trip timing, called Fine Timing Measurement, between APs and clients. Using the speed of light, this standard should provide an accurate measurement of range and motion -- again, using numerous samples to account for reflections and potential interference. The standard and products based on it are expected around 2020.
As is usually the case, success with location and tracking is ultimately all about the apps involved and how they use location data. Currently, the core challenge is how to improve the update rate so real-time tracking, where required, is common. But have no fear: These principles have been around for decades, and remarkable innovations in the location and tracking field have already resulted. This is an area of endeavor that's well on its way to becoming essential.
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