What is AQI (Air Quality Index) and how is it calculated? What is AQI (Air Quality Index) and how is it calculated?
AQI indicates WiFi health within an AP's cell, as indicated by a scale from 0 (unusable) to 100 (perfect). Airtime utilization shows how much of the access point airtime is being utilized by the clients that are associated to it.
There could be many reasons why the AQI is impacted. Some reasons are high utilization of the AP channel, clients using a slow data rate, co-channel or adjacent channel interference, or nearby non-802.11 wifi devices like Bluetooth devices, wireless video cameras, or outdoor microwave links. The AP itself has a channel switching mechanism to move out of the operating channel if the noise is in the channel is high.
If we receive an AQI Alert we can check what is causing the AQI to be poor. Is it Noise, OBSS load, or non-wifi interference? We can't do much for bursty noise and non-wifi interference. Since the 2.4 GHz band generally has more interference and congestion using the 5GHz band can help clients avoid interference, increasing the overall performance of the network.
We use the following parameters to calculate the AQI: self-chan-util, noise-floor, channel-load, obss-chan-util, total-rx-chan-util, total-chan-free, total-tx-chan-util, and total-non-wifi-util. Definitions of these parameters are at the bottom of the article.
Example of Bad AQI
As you can see from the below screenshot. here the AQI is dropped to 0 which is below the threshold value 35, and this will generate alerts on Nile Portal saying AQI is impacted for 2 mins /3 mins
Example of Good AQI
Here as you see AQI is above 35 and marked as 98 which indicates that the air quality is good and that no issues are ongoing with the APs
Nile Portal: AQI Statistics
How to check the AQI alerts from the Nile portal in detail:
- Click on the Air quality tile under infrastructure. Select the respective building in Red
2. This will list out all the air quality-related events on the bottom right of the page
3. Check for the detailed view of AQI with the respective time/location
4.Select the time slot
5. Click on the Red circle in the map which indicates the AP that has generated bad AQI
6. We should be seeing the threshold and AQI values for the respective time frame
Definitions of AQI calculation parameters
- Self-chan-util: Self-channel-util will be the sum of total-tx-chan-util and total-rx-chan-util.
- Noise-floor: The Noise Floor is the signal created from adding up all the unwanted signals within a measurement system.
- channel-load: the percentage of the channel usage in time.
- obss-chan-util: obss-chan-util reflects the co-channel wifi interference seen in the current channel.
- total-rx-chan-util: Rx utilization is the percent of radio channel utilization in RX, receive traffic from client.
- total-chan-free: Percentage of radio channels that are free for transmission.
- total-tx-chan-util: tx channel utilization is the percent of radio channel utilization in Tx, sent traffic from AP.
- total-non-wifi-util: Total-non-wifi-util reflects the non-wifi channel utilization seen in the channel which is the sum of non-wifi interference and adj. channel interference seen in the current channel
