Designing The Wireless Lan; Planning Channel Usage; Ghz (802.11A) - Cisco 7925G Deployment Manual

Note: If using Coexistence where 802.11b/g and Bluetooth are being used simultaneously, then multicast voice is not
supported.

Designing the Wireless LAN

The following network design guidelines must be followed in order to accommodate for adequate coverage, call capacity and
seamless roaming for the Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G.

Planning Channel Usage

Use the following guidelines to plan channel usage for these wireless environments.

5 GHz (802.11a)

The Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G support Dynamic Frequency Selection (DFS) and
Transmit Power Control (TPC) from 802.11h, which are required when using channels operating at 5.260 - 5.700 GHz (15 of
the 23 possible channels).
DFS dynamically instructs a transmitter to switch to another channel whenever radar signal is detected. If the access point
detects radar, the radio on the access point goes on hold for at least 60 seconds while the access point passively scans for
another usable channel.
TPC allows the client and access point to exchange information, so that the client can dynamically adjust the transmit power.
The client uses only enough energy to maintain association to the access point at a given data rate. As a result, the client
contributes less to adjacent cell interference, which allows for more densely deployed, high-performance wireless LANs.
5 GHz channels overlap their adjacent channel, so there should be at least 1 channel of separation for adjacent access points.
Need to ensure there is at least 20 percent overlap with adjacent channels when deploying the Cisco Unified Wireless IP Phone
7925G, 7925G-EX, and 7926G in the 802.11a environment, which allows for seamless roaming. For critical areas, it is
recommended to increase the overlap (30% or more) to ensure that there can be at least 2 access points available with -67 dBm
or better, while the Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G also meet the access point's receiver
sensitivity (required signal level for the current data rate).
Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G Deployment Guide
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