802.11A Deployment Considerations; Access Point Configuration Considerations; Channel Selection - Polycom SpectraLink 8020 Deployment Manual

Deploying SpectraLink 8020/8030
Wireless Telephones
July 2009
2.3

802.11a Deployment Considerations

The 802.11a standard utilizes the 5.1 GHz to 5.8 GHz Unlicensed National Information Infrastructure
(UNII) frequency spectrum. Although having the same maximum throughput as 802.11g (54 Mb/s), the
increased frequency spectrum at 5 GHz offers up to 23 channels, providing the potential for higher AP
density and increased aggregate throughput. There is significant variation in channel availability and use
between countries, however, which must be considered for any particular 802.11a deployment.
As compared with the 2.4 GHz frequency of 802.11b/g radio deployments, higher frequency RF signals
utilized by the 802.11a 5GHz band do not propagate as well through air or obstacles. This typically
means that an 802.11a network will require more APs than an 802.11b/g network to provide the same
level of coverage. This should be taken as a guideline however, as signal propagation may also be
impacted by the output power settings of the AP and the antenna type. A comprehensive wireless site
survey focusing on VoWLAN deployments should be conducted to identify the specific needs for each
environment.
2.4

Access Point Configuration Considerations

There are several fundamental access point configuration options that must be considered prior to
performing a site survey and deploying a voice-capable WLAN infrastructure. SpectraLink handsets
provide support for 802.11b, 802.11g and 801.11a radio types. The selection of radio type has significant
impact on the overall configuration and layout of the WLAN infrastructure. This fundamental selection
determines most other configuration considerations. In general, however adjacent APs in three
dimensions (above, below and beside) must use different non-overlapping radio channels to prevent
interference between them regardless of 802.11 radio type.
This document does not cover all issues or considerations for WLAN deployment. It is strongly
recommended that Polycom Professional Services, or another suitable professional services
organization, with wireless voice deployment experience be engaged to answer additional questions
about configurations that may affect voice quality or wireless telephone performance. In addition, VIEW
Configuration Guides for WLAN infrastructure, which are available from the Polycom web site, should be
followed closely.
2.4.1

Channel Selection

The 802.11b/g standard provides for three non-interfering, non-overlapping frequency channels -
channels one, six and eleven in North America. Access points within range of each other should always
be set to non-interfering channels to maximize the capacity and performance of the wireless
infrastructure. Figure 2 illustrates the correct deployment methodology for 802.11b/g deployments.
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