Installation Guidelines - Cisco Aironet 1550 Series Hardware Installation Manual

Installation Guidelines

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
Under no circumstances should you connect the antenna port from one access point to the antenna port
Caution
of another access point 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 access
point 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.
Installation Guidelines
Because the access point is a radio device, it is susceptible to common causes of interference that can
reduce throughput and range. Follow these basic guidelines to ensure the best possible performance:
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To calculate path loss and to determine how far apart to install access points, consult an RF planning
Note
expert.
Site Surveys
Every network application is a unique installation. Before installing multiple access points, you should
perform a site survey to determine the optimum use of networking components and to maximize range,
coverage, and network performance.
Consider the following operating and environmental conditions when performing a site survey:
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Cisco Aironet 1550 Series Outdoor Mesh Access Point Hardware Installation Guide
2-8
For information on planning and initially configuring your Cisco Mesh network, refer to the Cisco
Wireless Mesh Access Points, Design and Deployment Guide, Release 7.0.
Review the FCC guidelines for installing and operating outdoor wireless LAN devices at
http://www.cisco.com/en/US/partner/prod/collateral/routers/ps272/data_sheet_c78-647116_ps114
51_Products_Data_Sheet.html.
Perform a site survey before beginning the installation.
Install the access point in an area where structures, trees, or hills do not obstruct radio signals to and
from the access point.
The access points can be installed at any height, but best throughput is achieved when all the access
points are mounted at the same height. We recommend installing the access points no higher than
40 feet to allow support for wireless clients on the ground.
Data rates—Sensitivity and range are inversely proportional to data bit rates. The maximum radio
range is achieved at the lowest workable data rate. A decrease in receiver sensitivity occurs as the
radio data increases.
Antenna type and placement—Proper antenna configuration is a critical factor in maximizing radio
range. As a general rule, range increases in proportion to antenna height. However, do not place the
antenna higher than necessary, because the extra height also increases potential interference from
other unlicensed radio systems and decreases the wireless coverage from the ground.
Physical environment—Clear or open areas provide better radio range than closed or filled areas.
Chapter 2 Installing the Access Point
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