When designing a static channel plan for an office using voice devices near an airport, which range of channels should be avoided to ensure optimal performance when implemented?

One of your warehouse customers called you reporting problems with their WLAN in some locations that you designed and installed over a year ago. What should be one of your first considerations for your line of questioning?
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What document is typically created to launch a project?
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What kind of antenna results in a nearly circular pattern on the azimuth chart but a very flat donut shape on the elevation chart?

What are the deliverables to your customer after successfully implementing a WLAN infrastructure?