Channel Utilization

Channel Utilization describes how busy a WiFi channel is. It is a percentage that represents the amount of bandwidth being used on a WiFi channel. A higher percentage indicates a busier channel, resulting in reduced throughput. The calculated value varies based on the environment of the Access Point.

Channel utilization calculation

The channel utilization value is calculated based on these factors: 

• Transmit TX time: how much time was used for data transmission from WiFi client to the Access Point over the last hour (in milliseconds). 
• Receive RX time: how much time was used for data transmission from the Access Point to the WiFi client over the last hour (in milliseconds)
• Busy time: how much time was used by third parties for data transmission over the last hour (in milliseconds)
• Idle time: how much time there was unused capacity available for data transmission over the last hour (in milliseconds) 

Calculation

Total Utilization=Idle Time+Busy Time+Transmit Time+Receive Time

Channel Utilization=(Total Utilization−Idle TimeTotal Utilization)×100Channel Utilization=(Total UtilizationTotal Utilization−Idle Time​)×100

Best practices

High channel utilization can cause a variety of symptoms, including slow network performance, "missing" SSIDs, network timeouts or trouble connecting to network, and dropped network packets. Therefore, it should be kept at a healthy level. As a general guideline:

• Voice Traffic: Channel utilization should be below 20%.
• Video Traffic: Channel utilization should be below 50%.
• Data Traffic: Channel utilization should be below 75%.

Reducing channel utilization

High channel utilization can have a lot of reasons. Factors include:

• A high number of connected clients using the same channel can increase utilization.
• Interference with other wireless networks (nearby networks on the same channel),
• Used channel width (wider channels can carry more data but are more prone to interference),
• Overlapping channels have higher interference vs. non-overlapping channels.

The transmit and receive times mentioned above show how much channel utilization the Access Point radio is responsible for. When those values are low but the channel utilization is still high, it means that other nearby wireless devices are using the same channel (high 'busy time'). Now if those other wireless devices are Access Points in your network, the following can be done to reduce utilization:

• Use less SSIDs (maximum 3 is recommended),
• Disable 2.4 GHz radio in high interference environments,
• Disable lower data-rates so clients will try to roam earlier,
• Consider upgrading to higher performing Access Point models that are able to support more concurrent clients, 
• Install a sufficient amount of Access Points depending on the number of connected clients present in your network.

2.4 GHz band

High channel utilization also often occurs on the 2.4 GHz band due to the limited (non overlapping) channels and the fact that the 2.4 GHz frequency reaches much further than 5 GHz and 6 GHz frequency, increasing the presence of 2.4 GHz signals and the risk of interference. If your network consists of dual- or tri-band Access Points, consider disabling the 2.4 GHz band in high-interference environment. The Plasma Cloud console allows you to scan your RF environment and provides a visual chart per Access Point showcasing the wireless interference levels for each band. You can use the RF topology scan to get insights into how much interference is present on each WiFi radio. Enable the Ambient Noise filter. For details, please see this article.