Ekahau's T301 tags support two-way traffic
It's also refreshing that, unlike some competitors, Ekahau doesn't shy away from accuracy claims. Most Wi-Fi location vendors depend on exciters or choke points to enhance the precision and timeliness of location tracking, but Ekahau swears off most of these methods and emphasizes its Ekahau Positioning Engine and active tags.
Location systems generally take one of two approaches to pinpointing location. In a tag-centric, or associated, model, tags actively take power readings of surrounding access points at controlled intervals or based on predefined events, like tag movement, then report to the location engine by associating with an AP and transmitting, like a regular Wi-Fi client. It's two-way communications.
Alternatively, tags may work in simpler beaconing mode, where they "chirp" at fixed intervals. The Wi-Fi infrastructure understands this abbreviated packet, which contains the tag's unique identifier and perhaps some state information, and appends the measured power reading of the tag before sending it to the location engine.
Ekahau tags may be programmed to perform in beaconing mode, but the company expects that will be the case in less than 10% of its 2008 deployments. Rather, Ekahau favors a tag-centric approach to calculating location, which it says is more accurate than the beaconing route most rival Wi-Fi location vendors favor. A key ingredient is the Ekahau Location Survey software, which is used to calibrate the system. With ELS, a technician performs a site walk-through, recording his route into the network along the way. This data is then integrated into the location model that the engine uses to spit out coordinates.