How do you handle WiFi signal interferences from other companies around you?
I have seen better deployments taking the time to plan each of the listed above items. we used to just throw in a controller and plug the AP in and leave. But with so much WIFI Signals in the area, taking the time to plan for the best, really helps. - Thats with anything really. But get a tool that can scan other signals in the area. inSSIDer / Channelyzer / Ekahau
There is no way to prevent interference from WLANs from nearby companies being the 2.4 and 5 GHz bands are unlicensed frequencies that anyone can transmit on. Proper planning and design is your best bet. If they are transmitting on a stupid channel like channel 2, you can always go talk to them and ask them to use channel 1, 6 or 11 on the 2.4 band.