Signal Strength And Coverage - Cisco 9971 Deployment Manual

Non-overlapping channels must be used and allow at least 20 percent overlap with adjacent channels when deploying the Cisco
Unified IP Phone 9971 in the 802.11b/g environment, which allows for seamless roaming.
Using an overlapping channel set such as 1, 5, 9, 13 is not a supported configuration.

Signal Strength and Coverage

To ensure acceptable voice quality, the Cisco Unified IP Phone 9971 should always have a signal of -67 dBm or higher when
using 2.4 GHz or 5 GHz, while the Cisco Unified IP Phone 9971 also meets the access point's receiver sensitivity required
signal level for the transmitted data rate.
Ensure the Packet Error Rate (PER) is no higher than 1%.
A minimum Signal to Noise Ratio (SNR) of 25 dB = -92 dBm noise level with -67 dBm signal should be maintained.
It is recommended to have at least two access points on non-overlapping channels with at least -67 dBm signal with the 25 dB
SNR to provide redundancy.
To achieve maximum capacity and throughput, the wireless LAN should be designed to 24 Mbps. Higher data rates (36-54
Mbps) can optionally be enabled for other applications other than voice only that can take advantage of these higher data rates.
Recommended to set the minimum data rate to 11 Mbps or 12 Mbps for 2.4 GHz (dependent upon 802.11b client support
policy) and 12 Mbps for 5 GHz, which should also be the only rate configured as a mandatory / basic rate.
In some environments, 6 Mbps may need to be enabled as a mandatory / basic rate.
Due to the above requirements, a single channel plan should not be deployed.
Cisco Unified IP Phone 9971 Wireless LAN Deployment Guide
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