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Why Your Wi-Fi Sucks And How It Can Be Helped, Part 2

Coverage Areas

Before we delve into any hard testing, we felt it was important to give a sense of wireless coverage from each of our six access points. You’ve seen where the laptop systems are located within our environment. If we were running a normal office, the logical placement of the access point would be directly above the middle of our 60-client cluster (which is where we mounted our second access point, not the unit under test, during interference testing). So, to get an idea of how well each access point might serve such an environment in terms of coverage, we worked with commercial wireless solutions provider Connect802 to perform a thorough site survey for all six APs.

With a test notebook strapped into a harness and running AirMagnet Survey Professional Edition, our Connect802 technician made six complete walking tours of our office area. In the following images, you can see the path he walked marked by the little red arrows on each map.

We did make one modification from the software’s default setting. When our Connect802 specialist mentioned that an access point would need a roughly -70 to -75 dBm signal in order to hold a usable Wi-Fi connection, we had the technician change the color scale on his maps such that light blue hits at -75 dBm and light blue/green is at -70 dBm. This way, you can assume that green shading (and on into the stronger yellow and red zones) represents a dependable Wi-Fi signal.

In the 2.4 GHz range, HP clearly fares worst. Kudos to Apple for making a fairly equivalent showing to Aruba, Cisco, and Meraki, although note how Apple, Aruba, and Meraki all have one quirky dead spot in each of their decent coverage areas. Cisco and Ruckus do not share this problem. In terms of green coverage to the building’s far wall, Ruckus provides the most coverage.

With 5 GHz mapping, this second verse runs very similar to the first, only this time we’d give the nod to Cisco for having the most -70 dBm or better coverage. With its longer wavelengths, 2.4 GHz is known to be somewhat more penetrating and long-reaching than 5 GHz. Either way, though, such maps are essential when deploying wireless coverage across a broad area because you have to know how many APs you’ll need to service your users. Better coverage is one of the factors that lead to purchasing fewer APs.