Chapter 2 Installing the Access Point
Installation Guidelines
For a radiated test bed, 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 Under no circumstances should you connect the antenna port from one access point to the antenna port 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:
•For information on planning and initially configuring your Cisco Mesh network, refer to the Cisco Wireless Mesh Access Points, Design and Deployment Guide, Release 7.3.
•Review the FCC guidelines for installing and operating outdoor wireless LAN devices at
•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.
Note To calculate path loss and to determine how far apart to install access points, consult an RF planning 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:
Cisco Aironet 1550 Series Outdoor Mesh Access Point Hardware Installation Guide
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