Cisco Aironet 1570 Series, Руководство по установке

Страница: 39 / 168

2-5
Cisco Aironet 1570 Series Outdoor Access Point Hardware Installation Guide
OL-32138-01
Chapter 2 Preparing for Installation
Access Point Installation Guidelines
•
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.
Site surveys reveal problems that can be resolved before the network is operational. Because
802.11a/b/g/n/ac 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.
A proper site survey involves temporarily setting up mesh links and taking measurements to determine
whether your antenna calculations are accurate. Determine the correct locations and antenna types
before you drill holes and route cables and mounting equipment.
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 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.
•
Obstructions—Physical obstructions such as buildings, trees, or hills can hinder performance of
wireless devices. Avoid locating the devices in a location where there is an obstruction between the
sending and receiving antennas.
• How far is your wireless link?
•
Has a previous site survey been conducted?
• Do you have a clear Fresnel zone between the access points or radio line of sight?
•
What is the minimum acceptable data rate within the link?
• Do you have the correct antenna (if more than one antenna is being offered?)
•
Do you have access to both of the mesh site locations?
• Do you have the proper permits, if required?
•
Are you following the proper safety procedures and practices?