Wifi Design Cycle

I’m in the process of carrying out wifi improvement works on the campus, so I thought I’d write some pieces about our wifi equipment lifecycle and the processes I’m following.

Initial Survey
Pretty much everywhere has some wifi coverage. I’m therefore starting with an initial survey to find out what we currently have and inform what we need to change. Even if I know the coverage is terrible and I need to just start again, this survey is necessary to provide before and after documentation. It also shows how RF propagates through the building, which can help identify troublesome areas of attenuation that don’t show up on the plan. I try to identify where the available data points are at this stage, though it can be hard to be thorough about this.

The design stage is predictive, though it’s sense checked using the initial survey information.

Once there’s a new design, this gets deployed – this can be where some compromises occur as it turns out that ceiling cavity contains asbestos, or one of these data cables is damaged. Deployment is sometimes going to be done by me, sometimes by a contractor.

A repeat of the initial survey – validate the coverage is as expected, that APs are using sensible channels and we don’t have a Co-Channel Interference disaster, that 2.4GHz radios are on a sensible power setting or disabled as is appropriate. At this point there’s a loop back to design in the flowchart. If things are not looking as expected it’s back to the drawing board to find a remedy, then deploy physical or config changes and survey the area again. Recently I’ve carried out validation surveys in areas where I know an install compromise was made because the building structure wasn’t quite as expected. It was strangely satisfying to discover the original design was sound and the new AP position wasn’t working, so I had to come up with a different option.

This is an ongoing process, but it’s worth confirming the throughput for group of APs is in the expected range (hasn’t dropped horribly for a building) and retransmissions are at acceptable levels. We use Aruba Airwave which makes it easy to group APs into an area for graphing of basic metrics. When wifi is improved in a building we expect to see an increase in client count and throughput but that isn’t always the case. Improving coverage in a lab means tablets can be used for note taking; that might be one or two more devices, not something that’s going to impact the graph.

I also talk to the users. Let them know there’s been a change, if they don’t already know. Ask for feedback and encourage them to tell you if there’s an device they need to use that doesn’t work so well in some parts of the building. Hopefully the design and validation accounts for this, but…..  I’ll more to day about that in another post.

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