802.11B/G Deployment Considerations; 802.11A Deployment Considerations; Access Point Configuration Considerations; Channel Selection - Avaya 3616 Installation Manual

Installation Guide
Avaya handsets have a site survey mode that should be used to validate the signal strength the
wireless telephone is receiving from the AP.
Although it is possible that Avaya handsets may operate at signal strengths which are weaker than
those provided in the above table, real world deployments involve many RF propagation challenges
such as physical obstructions, interference and multi-path effects that impact both signal strength and
quality. Designing RF coverage to the required levels will provide an adequate buffer for these
propagation challenges, enabling a more reliable and consistent level of performance.

802.11b/g Deployment Considerations

802.11g networks that also support 802.11b-only clients must run in protected mode to enable
backward compatibility. Protected mode adds considerable overhead to each transmission which
ultimately translates into significantly reduced overall throughput. Avaya 3641 and 3645 wireless
telephones, which support 802.11a, b and g radio types, do not operate in protected mode. The
overhead associated with performing protected mode transmissions largely negates any benefits of
transmitting relatively small voice packets at higher 802.11g data rates. For this reason, when Avaya
3641 and 3645 handsets are installed on a mixed 802.11b/g network which is already running in
protected mode, the handset must be set to 802.11b mode.

2.2 802.11a Deployment Considerations

The 802.11a standard utilizes the 5.1 GHz to 5.8 GHz spectrum. Although having the same maximum
throughput as 802.11g (54 Mb/s), up to 23 channels may be available for use in 802.11a deployments,
providing the potential for higher AP density and therefore 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.

2.3 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. Certain Avaya 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 must
use different 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 Avaya, or another suitable professional services organization, be engaged to
answer additional questions about configurations that may affect voice quality or wireless telephone
performance. In addition, Avaya wireless telephones are compliant with Polycom's Voice
Interoperability for Wireless Voice (VIEW) program. The Configuration and Deployment Guides for
Polycom VIEW Certified and Field Verified WLANs should be closely followed. These are available
from the Polycom web site http://www.polycom.com/usa/en/support/voice/wi-fi/wi-fi.html.

2.3.1 Channel Selection

The 802.11b/g standard provides for three non-interfering channels - channels one, six and 11 for
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, diagram provided
below illustrates this deployment methodology.
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