Special caution needs to be taken when surveying multifloor facilities. APs
on different floors may be able to interfere with each other as easily as APs
located on the same floor. It is possible to take advantage of this during a
survey. By using larger antennas, it may be possible to penetrate floors and
ceilings and provide coverage to floors above and below the floor where the AP
is mounted.
In Figure
, a four-story
office complex needs to be covered. A single AP would not cover an entire
floor. Mounting two APs on each floor would be expensive and might present a
problem with APs on the same channel overlapping. Use patch antennas on the APs
to solve the problem. Because the patch antenna is semidirectional, there is
enough coverage from each AP to cover most of one floor and a portion of the
floors above and below it. By mounting APs on alternating floors and at
opposite ends of the building, the SE is able to achieve the desired coverage
with only four APs.