Cisco Aironet 340 Series Guide d'installation télécharger pdf (Page 27)

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Cisco Aironet Access Point Hardware Installation Guide

OL-0738-02

Chapter 2 Installation

Installation Guidelines

Heavy Overlap Coverage Option

By arranging the access points so the overlap in coverage area is nearly maximized, a large number of

mobile stations can be supported in the same wireless infrastructure (see Figure 2-3). However, devices

in overlapping coverage areas on the same frequency will detect adjacent cell traffic and delay

transmissions that would cause collisions. This configuration reduces the aggregate radio system

throughput. Heavy cell overlap is not recommended for maximum system throughput.

Because of the redundancy in coverage overlap, network access is not lost if an access point fails. Upon

failure of the access point, the station automatically roams to an operational access point. With this

architecture, each device in the RF network must be configured with the same SSID to provide the

roaming capability.

Figure 2-3 Heavy Overlap Coverage Option

Site Surveys

Because of differences in component configuration, placement, and physical environment, every

network application is a unique installation. Before installing multiple access points, you should perform

a site survey to determine the optimum utilization of networking components and to maximize range,

coverage, and network performance.

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 threshold 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.

• Physical environment – Clear or open areas provide better radio range than closed or filled areas.

Also, the less cluttered the work environment, the greater the range.

• Obstructions – A physical obstruction such as metal shelving or a steel pillar can hinder performance

of wireless devices. Avoid locating the devices in a location where there is a metal barrier between

the sending and receiving antennas.

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Wired LAN

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Cisco Aironet 340 Series Guide d'installation Page 27