I think the AP1131AG is designed to deploying on the ceiling. It has 360 degree omni antenna. but how about deploy on the wall? Is the pattern of RF changed omni to patch?
I believe that in either case, the radiation pattern is a hemisphere (~180degrees).
When hung form the ceiling (dome down), it covers the horizontal @ 360 degrees, floor to ceiling.
When hung on the wall, it covers from (mounting)wall-to-(mounting) wall, 180 degrees, floor to ceiling.
The signal polirity (probably) changes. Depending on your hosts, it may be a Good Thing or a Bad Thing (Laptops using PC Cards tend to be horizontal polorization, laptops with built-in wireless tend to be vertical polorization, PCs with wireless NICs tend to be vertical, USB-based wireless could be either ... depends on the form-factor).