5-2
Site Survey Guide for Deploying Cisco 7920 IP Phones
OL-6315-01
Chapter 5 Positioning Access Points and Antennas for Site Surveys
Antennas and Antenna Positioning
The access point in Figure 5-2 provides better coverage because the reflected signal produces fewer nulls
and less multipath than the I-beam placement. However, because there is only one floor in this industrial
building, there is no need for the antennas to be above the access point. The signal could be improved
by inverting the access point so that the antennas point to the ground.
Figure 5-2 Access Point Installed on a Wall
Antennas and Antenna Positioning
Interference and multipath cause the transmitted signal to fluctuate. Interference increases the required
signal-to-noise ratio for a particular data rate. The packet retry count goes up in areas where interference
or multipath are high. Changing the type and location of the antenna can reduce multipath interference.
Antenna gain adds to the system gain and improves the signal-to-noise requirement.
Figure 5-3 shows proper positioning of the antennas on a dual-radio access point mounted on a
suspended ceiling. Both the removable antennas and the paddle antenna are pointed down at the floor.
Figure 5-3 Access Point Installed on a Suspended Ceiling
