The MetaGeek office in downtown Boise is within walking distance of a Whole Foods market, so most workdays I walk over there during my lunch break. It’s a long walk which gives me some exercise (and a ton of steps) and I usually average around $6 for a healthy, well-portioned lunch. Since I am also in “test the heck out of Air Viewer mode,” earlier this week I said to myself, “why not put the Wi-Spy Air in my pocket and see what their WiFi environment looks like.”
As I was eating my lunch (a yummy kale salad and chicken), I got out my Wi-Spy Air and launched Air Viewer on my phone. I was at first surprised to see all of the virtual (and hidden) SSIDs they have going on. I was then a little more surprised at the channel planning and channel re-use that they have configured.
The below screenshot shows that their APs near where I was sitting were broadcasting on 3 different channels and that there were 2 radios in range broadcasting the network on each of the 3 channels. The concerning part, though, was that they were broadcasting at nearly the same levels, making it difficult for my client to choose which radio it might want to associate to. It also added to the to co-channel interference situation, since about 13 BSSs were broadcasting on each of these channels.
After I finished my lunch in the dining area, I was curious what the rest of the store would look like from Air Viewer’s perspective. As I moved through the floor space, I noticed quite a few Cisco APs hanging above the aisles (I counted about 12 total). The channel planning was much of the same: broadcasting on 36, 44, and 149 throughout and the signal strength almost always in the green.
Since this is what I saw, let’s now talk a little about what I would have expected for channel planning and re-use. First, I would have expected signal strengths at a given location to favor one channel over the others that are broadcasting the Whole Foods SSID. This way my client knows which radio is the best to connect to based on my location and so that it will roam to a new AP more fluidly as I walk the floor. Secondly, I would expect more channels to be used so that there is less same-channel overlap, meaning less overhead and contention, which increases throughput potential.
For some more helpful information on channel planning and channel re-use, below is a visualization of channel planning that we use in our training material. What we recommend is for each of the different shaded colors to be a specific channel and that colors (channels) are spaced out so that they don’t overlap. Also, here is a knowledge base article on channel planning for further reference.