Nov 23, 2007 (07:11 PM EST)
AeroScout Keeps Tabs On Movable Assets

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THE UPSHOT
CLAIM:  AeroScout provides a complete enterprise-class Wi-Fi location system that's flexible and scalable enough to work within most environments. With its tag, location engine, and viewer, it provides as complete a lineup of Wi-Fi location products as anyone. It offers readers that can use TDOA plus exciters for precise and immediate location detection..

CONTEXT:  Without Wi-Fi locationing, valuable time is wasted hunting down items or people, and you'll miss out on security capabilities. Our latest Rolling Review evaluates this emerging market.

CREDIBILITY:  AeroScout offers a wide variety of tags in all kinds of packages and mounting options. Tag certification and a strong product relationship with Cisco suggest market permanence. AeroScout recommends that customers use its MobileView user interface; we'd prefer to see the company develop partnerships with third-party app vendors.

AeroScout, a well-known player in the Wi-Fi location market, focuses less on pinpoint accuracy, more on integrating with Wi-Fi networks to provide ubiquitous visibility into the whereabouts of assets and people. It has arguably the most comprehensive set of hardware and software products of any location vendor, offering tags in multiple form factors as well as chokepoints for sending alerts and a locationing engine that can process location from its tags based on TDOA (time difference of arrival) in addition to RSSI (received signal strength indication).

AeroScout's tags, which it developed in-house, differ from those of its main competitor. Rather than have a tag take readings, associate with an access point, and then communicate with a location engine, AeroScout's tags regularly "chirp" or "beacon" a 416-bit 802.11 frame. This approach reduces tag/access point interaction to a simple unidirectional packet. No state for the access point to maintain and no IP address required--and less radio time means longer battery life.

On the other hand, the Wi-Fi infrastructure needs to be able to listen for and interpret this packet, despite the lack of association, and send it on to the locationing engine. This requires enterprise Wi-Fi gear vendors to buy into the concept and add support for AeroScout's message. Fortunately, according to AeroScout, more than 95% of enterprise access points support its tags today. For Cisco Systems Lightweight Access Point Protocol, or LWAPP, environments, location information is sent to the Cisco Location Appliance and Wireless Control System rather than AeroScout's engine.

Another caveat is that tag messages can be cloned. Because there's no authentication or two-way verification, once tag communication is captured, it can be played back on any device. AeroScout says its engine can filter fake messages and toss erroneous readings.

A TAG FOR EVERY PURPOSE

Tags are available with a variety of mounting options in multiple form factors, from ruggedized packages to small portable units and personnel badges. In AeroScout's T3 model, motion sensors conserve battery life when the asset is stationary. Optional temperature sensors can help ensure that sensitive items are within the proper environment. Two call buttons are standard on the T3 model. The replaceable battery operates up to four years, and available extended batteries may last as long as eight years. AeroScout's T3 tag also includes infrared support for over-the-air firmware upgrades. Tags can be set to turn themselves on or off as they go through chokepoints, as when an employee is leaving the building, or to sense if an expensive item walks out the door.

Completing the picture is AeroScout's engine, which receives location reports and calculates the positions of tags. AeroScout's own algorithms use RSSI, a value appended by the access point or WLAN controller to the tag's beacon, to calculate location. Data on the tag's previous position, the AP's location, and fingerprinting helps tighten accuracy to perhaps 3 meters, depending on environment and the location and density of APs. We don't see scalability as a concern. A single engine can handle 500 location reports per second, and multiple engines can feed into one MobileView server, described later.

AeroScout is a key Cisco partner, unlike its main competitor, Ekahau. AeroScout's Web-based MobileView shares with Cisco's Location Appliance and Wireless Control System a common set of management information, including site maps. Cisco often bundles its location appliance into larger enterprise WLAN deals but doesn't make tags itself. AeroScout's tags have passed Cisco's CCX certification program for Wi-Fi tags.

InformationWeek's Rolling Reviews present a comprehensive look at a hot technology category, beginning with market analysis and wrapping up with a synopsis of our findings. For consideration, contact the author .