I have been asked to help out in setting up a wireless network for a medical center. We have plenty of time before it opens so now is the time to test. I would like to recommend some kind of redundancy among the AP's. Right now it will take about 16 to cover the area. Being a medical facility, if one AP in the ICU fails, best if the client devices connect to a another one. My question, am I right in saying we need a controller to accomplish this? I built and installed the wired LAN, so here's my chance to build my wireless skills
The best way to build redundancy into your wireless infrastructure is to use a design concept called "microcells". By installing more APs at smaller radio strength, you have the luxury of increasing the signal strength of a nearby AP if one should fail. Consider the alternative, which is to install less APs at 100% power, but if one fails you cannot increase the power of nearby APs.
Now, a controller can automatically adjust nearby APs' power levels when this happens, but it can be handled manually in an autonomous environment.
Finally, if you already have installed a wireless infrastructure at 100% power, you can install redundant APs in a standby mode. The backup AP monitors the active AP, and it immediately turns on if the active AP fails. You would typically install these APs right next to the active ones.
Regardless of the redundancy used, the clients will see a hiccup in service when the AP goes down. This cannot be prevented, though roaming to the new AP should be extremely fast. This will only affect you if you're using delay-sensitive applications, and even then it might not be noticed.
I hope that helps! Let me know if you have any questions.