Performing Site Surveys - Cisco Catalyst IW9167E Hardware Installation Manual

Performing Site Surveys

Note
• Reduce the configured transmit power to the minimum level.
• Use directional antennas, and keep them away from each other.
• Cable the radios together using a combination of attenuators, combiners, or splitters to achieve a total
For a radiated testbed, the following equation describes the relationships among transmit power, antenna gain,
attenuation, and receiver sensitivity:
txpwr + tx gain + rx gain - [attenuation due to antenna spacing] < max rx input level
Where:
txpwr = Radio transmit power level
tx gain = transmitter antenna gain
rx gain = receiver antenna gain
For a conducted test bed, the following equation describes the relationships among transmit power, antenna
gain, and receiver sensitivity:
txpwr - [attenuation due to coaxial components] < max rx input level
Caution
Performing Site Surveys
Every network application is a unique installation. Before installing multiple APs, you should perform a site
survey to determine the optimum use of networking components and maximize range, coverage, and network
performance.
Site surveys reveal problems that can be resolved before the network is operational. Because 802.11a/b/g/n/ac/ax
operates in an unlicensed spectrum, there may be sources of interference from other 802.11a wireless devices
(especially in multi-tenant buildings) that could degrade your 802.11 signals. A site survey can determine if
such interference exists at the time of deployment.
Consider the following operating and environmental conditions when performing a site survey:
• Data rates: Sensitivity and range are inversely proportional to data bit rates. The maximum radio range
Cisco Catalyst IW9167E Heavy Duty Access Point Hardware Installation Guide
60
These distances assume free space path loss and are conservative estimates. Required separation distances
for damage and performance degradation levels in actual deployments are less if conditions are not
non-line-of-sight.
attenuation of at least 60 dB.
Under no circumstances should you connect the antenna port from one AP to the antenna port of another AP
without using an RF attenuator. If you connect antenna ports, you must not exceed the maximum survivable
receive level of 0 dBm. Never exceed 0 dBm, or damage to the AP can occur. Using attenuators, combiners,
and splitters having a total of at least 60 dB of attenuation ensures that the receiver is not damaged and that
PER performance is not degraded.
is achieved at the lowest workable data rate. A decrease in receiver sensitivity occurs as the radio data
increases.
Safety Guidelines and Warnings