361| Adaptive Radio Mana gement (ARM ) DellPowerConnect W- Series ArubaOS 6.2 | User Guide
802.11 noise from devices such as Bluetooth headsets, video monit ors and cordlessphones.
You can configurethe nois e immunity featurefor any one of t he followinglevels of noise sensiti vity. Note that
increasingt helevel makes the AP slightly “deaf” to its surroundings,causing the AP to lose a small amount of range.
lLevel0 : no ANI adaptation.
lLevel1 : Noise immunity only. This level enables power-based packet detection by controlling the amount of
power increaset hat makesa radio aware that it has received a packet.
lLevel2 : Noise and spuri mmunity.This level also controls the detection of OFDM packets, and is the default
setting for the Noise Immunity feature.
lLevel3 : Level 2 settings and weak OFDM immunity. This level minimizes false detects o n the radio due to
interference,but may also reduce radio sensiti vity. This level is recommended for environments with a high-level
of interferencerelated to 2.4Ghz appliances such as cordless phones.
lLevel4 : Level 3 settings, and FIR immunity. At this level, the AP adjusts its sensitivity to in-band power, which
can improve performancein environments with high and constant levels of noise i nterference.
lLevel5 : The AP completely disables PHY error reporting, improving performanceby eliminati ngt he time the
controllerwould spend on PHY processing.
NOTE:Only 802.11n-capable APs simultaneously support both theR X Sensitivity Tuning BasedC hannel Reuse featureand a l evel-3
tolevel-5 Noise Immuni tysetting. Do not raise the noise immunity default setting on APs thatdo not support 802.11n unless youfirst
disable theC hannel Reuse feature.
You can manageN on-802.11 Noise Immunity sett ings throughthe 8 02.11g RF management profile. For details refer
to “RF Management” on page433.
ARM Metrics
ARM computes coverage and interferencemetrics for each valid channel and chooses the best performingc hannel
and transmit power settings for each AP��s RF environment. Each AP gathers other metrics on their ARM-assigned
channelto provide a snapshot of the current RF health state.
The followingt wo metrics help the AP decide which channel and transmit power setting i s best.
lCoverage Index: The AP uses this metric to measure RF coverage. The coveragei ndexis calculated as x/y, where
“x” is the AP’s weighted calculation of the Signal-to-Noise Rat io (SNR) on all valid APs on a specified 80 2.11
channel,and “y” is the weighted calculation of the Dell AP's SNR the neighboring APs see on that channel.
To view these values for an AP in yo urcurrent 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 w hich you want to view information.
lInterference Index: The AP uses this metric to measure co-channel and adjacent channel interference.The
InterferenceIndex is calculated as a/b//c/d, where:
lMetric value“a” is the channel interferencethe AP sees on i ts selected channel.
lMetric value“b” is the interference the AP sees on the adjacent channel.
lMetric value“c ” is the channelinterference the AP’s neighbors see on the selected channel.
lMetric value“d” is the interference the AP’s neighborss eeo nt headj acentc hannel
To manuallycalculate the total Interference Index for a channel,issue the CLI command show ap arm rf-
summary ap-name <ap-name>,then add the values

a+b+c+d.

Each AP also gathers the following additional metrics,w hichcan provide a snapshot of the current RF health state.
View these values for each AP using the CLI c ommandshow ap arm rf-summary ip-addr <ap ip address>.
lAmount of Retry frames (measuredi n %)
lAmount of Low-speed frames (measuredin %)