Users Guide

Dell PowerConnect W-Series ArubaOS 6.1 | User Guide Spectrum Analysis | 627
Channel Metrics
This stacked bar chart can show one of three different types of channel metrics; channel utilization, channel
availability, or channel quality.
By default, this chart displays channel utilization data, showing both the percentage of each monitored channel
that is currently being used by Wi-Fi devices, and the percentage of each channel being used by non-Wi-Fi
devices and 802.11 adjacent channel interference (ACI).
The Channel Metrics graph can also show channel availability, the percentage of each channel that is available for
use, or display the current relative quality of selected channels in the 2.4 GHz or 5 GHz radio bands. Spectrum
monitors can display data for all channels in their selected band. Hybrid APs display data for their one monitored
channel only.
In the spectrum analysis feature, channel quality is a relative measure that indicates the ability of the channel to
support reliable Wi-Fi communication. Channel quality, which is represented as a percentage in this chart, is a
weighted metric derived from key parameters that can affect the communication quality of a wireless channel,
including noise, non-Wi-Fi (interferer) utilization and duty-cycles, and certain types of retries. Note that channel
quality is not directly related to Wi-Fi channel utilization, as a higher quality channel may or may not be highly
utilized.
When you hover your mouse over any bar in the chart, a tooltip displays the metric value for that individual
channel. The example below shows that 61% of channel 3 is being consumed by non-Wi-Fi devices and 802.11
adjacent channel interference.
Show lines for these
channels
The Active Devices Trend chart can display values for up to five different device types on different
channels for a spectrum monitor, or a single device type for a hybrid AP.
To choose which type of data each line should represent, click the channel number drop-down list
and select a channel within the radio band, then click the device type drop-down list and select
one of the following device types.
 WiFi (AP)
 Microwave (This option is only available for 2.4 GHz radios)
 Bluetooth (This option is only available for 2.4 GHz radios)
 Fixed Freq (Others)
 Fixed Freq (Cordless Phones)
 Fixed Freq (Video)
 Fixed Freq (Audio)
 Freq Hopper (Others)
 Freq Hopper (Cordless Network)
 Freq Hopper (Cordless Base)
 Freq Hopper Xbox (This option is only available for 2.4 GHz radios)
 Microwave (Inverter) (This option is only available for 2.4 GHz radios)
 Generic Interferer
Select the checkbox beside each channel and device entry to show that information on the chart,
or unselect the checkbox to hide that information. For more information on non-Wi-Fi device types
detected by a spectrum monitor, see “Non-Wi-Fi Interferers” on page 646.
Table 130 Active Devices Trend Options (Continued)
Parameter Description
NOTE: ACI refers to the interference on a channel created by a transmitter operating in an adjacent channel. A transmitter on a
nonadjacent or partially overlapping channel may also cause interference, depending on the transmit power of the interfering
transmitter and/or the distance between the devices. In general, ACI may be caused by a Wi-Fi transmitter or a non-Wi-Fi
interferer. However, whenever the term ACI appears in Spectrum Analysis graphs, it refers to the ACI caused by Wi-Fi
transmitters. The channel utilization option in the Channel Metrics Chart shows the percentage of the channel utilization due to
both ACI and non-Wi-Fi interfering devices. Unlike the ACI shown in the Interference Power chart, the ACI shown in this graph
indicates the percentage of channel time that is occupied by ACI or unavailable for Wi-Fi communication due to ACI.