Wireless Basics: CleanAir and Event Driven (ED-RRM) RRM

CleanAir and Event Driven (ED-RRM) RRM

The Cisco CleanAir solution leverages spectrum intelligence to proactively manage the challenges posed by a shared ISM spectrum. On a shared spectrum, you are able to see other devices that are not 802.11 compatible. 

The system also provides you with an opportunity to take action based on this information. For example, you could remove the interfering device manually or make a change in the channel to avoid it automatically.

Fig 1.1- Cisco CleanAir

The following two mitigation mechanisms can be used to mitigate the effects of non-802.11 interference automatically: Event Driven RRM (ED-RRM) and Persistent Device Avoidance (PDA).Bypassing the normal RRM intervals and quickly changing channels for an AP in distress, ED-RRM allows an AP to respond to a distress state more quickly (30 seconds).

Fig 1.2- CleanAir

CleanAir APs also offer PDA mitigation. Periodically operating devices, such as microwave ovens, can introduce destructive levels of interference. Upon shutting down the device, the air returns to normal. 

In order to prevent future interference, the PDA system remembers those interferers and refuses to assign channels where those devices operate. In the event that the device does not appear again for 7 days, it is erased. The clock starts again when it encounters it again.

Event Driven RRM (ED-RRM)
An AP in distress can bypass normal RRM intervals using Event Driven RRM (ED-RRM) to change channels instantly. CleanAir APs constantly monitor Air Quality and report on it every 15 seconds. 

Because Air Quality only measures Classified Interference devices, it is a better metric than normal Wi-Fi chip noise measurements. Therefore, Air Quality is a reliable metric since it can be assumed that what is reported is not a transient spike due to Wi-Fi.