Users Guide

Dell PowerConnect W-Series ArubaOS 6.1 | User Guide Adaptive Radio Management (ARM) | 175
 Dynamic mode: In this mode, the Clear Channel Assessment (CCA) thresholds are based on channel loads,
and take into account the location of the associated clients. When you set the Channel Reuse feature to
dynamic mode, this feature is automatically enabled when the wireless medium around the AP is busy greater
than half the time, and the CCA threshold adjusts to accommodate transmissions between the AP its most
distant associated client.
 Disable mode: This mode does not support the tuning of the CCA Detect Threshold.
The channel reuse mode is configured through an 802.11a or 802.11g RF management profile. For details on
modifying 802.11a or 802.11g RF management profiles, refer to “RF Management (802.11a and 802.11g)
Profiles” on page 232.
Non-802.11 Noise Interference Immunity
When an AP attempts to decode a non-802.11 signal, that attempt can momentarily interrupt its ability to
receive traffic. The noise immunity feature can help improve network performance in environments with a high
level of non-802.11 noise from devices such as Bluetooth headsets, video monitors and cordless phones.
You can configure the noise immunity feature for any one of the following levels of noise sensitivity. Note that
increasing the level makes the AP slightly “deaf” to its surroundings, causing the AP to lose a small amount of
range.
 Level 0: no ANI adaptation.
 Level 1: Noise immunity only. This level enables power-based packet detection by controlling the amount of
power increase that makes a radio aware that it has received a packet.
 Level 2: Noise and spur immunity. This level also controls the detection of OFDM packets, and is the default
setting for the Noise Immunity feature.
 Level 3: Level 2 settings and weak OFDM immunity. This level minimizes false detects on the radio due to
interference, but may also reduce radio sensitivity. This level is recommended for environments with a high-
level of interference related to 2.4Ghz appliances such as cordless phones.
 Level 4: Level 3 settings, and FIR immunity. At this level, the AP adjusts its sensitivity to in-band power,
which can improve performance in environments with high and constant levels of noise interference.
 Level 5: The AP completely disables PHY error reporting, improving performance by eliminating the time the
controller would spend on PHY processing.
You can manage Non-802.11 Noise Immunity settings through the 802.11g RF management profile. Do not raise
the noise immunity feature’s default setting if the RX Sensitivity Tuning Based Channel Reuse feature is also
enabled. A level-3 to level-5 Noise Immunity setting is not compatible with the Channel Reuse feature. For
details refer to “Mesh Radio Profiles” on page 227.
ARM Metrics
ARM computes coverage and interference metrics for each valid channel and chooses the best performing
channel and transmit power settings for each AP’s RF environment. Each AP gathers other metrics on their ARM-
assigned channel to provide a snapshot of the current RF health state.
The following two metrics help the AP decide which channel and transmit power setting is best.
 Coverage Index: The AP uses this metric to measure RF coverage. The coverage index is calculated as x/y,
where “x” is the AP’s weighted calculation of the Signal-to-Noise Ratio (SNR) on all valid APs on a specified
802.11 channel, and “y” is the weighted calculation of the Dell APs SNR the neighboring APs see on that
channel.
To view these values for an AP in your current WLAN environment issue the CLI command show ap arm rf-
summary ap-name <ap-name>, where <ap-name> is the name of an AP for which you want to view
information.