Hi there,
We have many of the 1130 series mounted this way due to our campus environment.
There does not seem to be a significant performance hit with this method of mounting
Here is the "best practice" from Fred Niehaus @ Cisco;
If you look at the AP logo / LED light that part should be pointing down toward the users. The integrated antennas (six of them) are all designed to radiate best from an type of deployment as the antenna radiates DOWN and OUTWARD in a 360 degree pattern.
Best coverage is when the AP is closest to the actual users, if you mount them really high on the ceiling the signal has to travel that extra height (distance) as the AP is naturally further away from the users.
Try moving some data (pinging with large packets) and see what coverage you actually have at 6-8 Ft and then characterize how it looks higher in the ceiling.
Ideally you want the AP at 6-8 Ft and close as practical the users but reasonable success can happen with the AP higher. Avoid mounting the AP on a wall or upside down with the metal plate (down toward the user) - because if you do that the radiation pattern is not ideal. Wall mounting works best with the coverage area needed is less such as classrooms, small conference rooms kiosks etc.
ASK THE EXPERT - CISCO AP-1140 ACCESS POINT
https://supportforums.cisco.com/message/497273#497273
Cheers!
Rob
