Cisco Cisco Aironet 3500p Access Point Libro blanco
Copyright © 2010 Miercom
Cisco CleanAir Competitive
Page 12
Multiple Sources of Interference – 2.4GHz Band
We wanted to determine if CleanAir and AirDefense could correctly classify multiple interferers if
operating simultaneously.
operating simultaneously.
We used two video surveillance cameras, one on Channel 1, and the other on Channel 11.
Cisco correctly classified both sources of interference as video cameras, reporting that one was
affecting channels 1-4, and the second affecting channels 9-11. It also displayed the physical
location on the floor plan.
Cisco correctly classified both sources of interference as video cameras, reporting that one was
affecting channels 1-4, and the second affecting channels 9-11. It also displayed the physical
location on the floor plan.
Motorola triggered alarms on both sensors and on the access point but was unable to determine
if one device or multiple devices were causing the alarms. Each sensor and the access point
showed a single interference alarm.
if one device or multiple devices were causing the alarms. Each sensor and the access point
showed a single interference alarm.
We then added additional interferers. The multiple interference sources consisted of a 2.4GHz
DECT phone, a 2.4GHz video camera, a Bluetooth headset, and a microwave oven.
DECT phone, a 2.4GHz video camera, a Bluetooth headset, and a microwave oven.
Cisco detected, classified, and located all devices accurately. The microwave oven location icon
was initially hidden by the video camera location icon.
was initially hidden by the video camera location icon.
Motorola detected and set an alarm for a continuous wave device (the video camera) at
2462MHz, and also correctly classified the microwave oven, but was unable to detect the DECT
phone or the Bluetooth headset as frequency hopping devices.
2462MHz, and also correctly classified the microwave oven, but was unable to detect the DECT
phone or the Bluetooth headset as frequency hopping devices.
Single Interferers – 5GHz Band
We also examined each product’s ability to classify single interference sources in the
5GHz band.
5GHz band.
Beginning with the DECT cordless phone, Cisco was able to detect and properly classify
and locate the device as a “DECT-like phone.”
and locate the device as a “DECT-like phone.”
As previously shown in the 2.4GHz testing, the low duty cycle hampered Motorola to detect
and it did not trigger any alarms.
and it did not trigger any alarms.
To increase duty cycle of the interference, we added a handset and made it active. Cisco again
correctly classified and mapped the location of the phone. Motorola intermittently detected and
set alarms for a frequency hopper on one sensor only, but not on the access point.
correctly classified and mapped the location of the phone. Motorola intermittently detected and
set alarms for a frequency hopper on one sensor only, but not on the access point.
With three phones active, the Motorola AP and both sensors detected and set alarms for a
frequency hopper. Cisco classified and located all three phones correctly.
frequency hopper. Cisco classified and located all three phones correctly.
We then placed a 5GHz video camera into the environment. Motorola was unable to detect or
identify the interference, possibly because the duty cycle of the interference was insufficient to
cross the threshold to trigger an alarm. Cisco was able to classify and locate the video camera
accurately.
identify the interference, possibly because the duty cycle of the interference was insufficient to
cross the threshold to trigger an alarm. Cisco was able to classify and locate the video camera
accurately.
A summary of the interference source and how it was detected and classified is shown in
Figure 3
on page 13.