Be aware of the meaning of the model name and consequently its radiation pattern:
c=ceiling omnidirectional (360°, at least in theory)
w=wall directional 90° to maybe 120° or so.
The radiation pattern of the Wap seems to be like an off center ball with a flat bottom, see:
http://forum.mikrotik.com/t/wap-coverage-picture-included/179859/1