Information About Cisco CleanAir
Cisco CleanAir is a solution designed to proactively manage the challenges of a shared wireless spectrum. It allows you to see all the users of a shared spectrum (both native devices and foreign interferers). It also enables the network to act upon this information. For example, you can manually remove the interfering device, or the system can automatically change the channel away from the interference. CleanAir provides spectrum management and Radio Frequency (RF) visibility.
A Cisco CleanAir system consists of CleanAir-enabled access points and Cisco Catalyst 9800 Series Wireless Controller . These access points collect information about all the devices that operate in the industrial, scientific, and medical (ISM) bands, identify and evaluate the information as a potential interference source, and forward it to the controller . The controller controls the access points and displays the interference devices.
For every device operating in the unlicensed band, Cisco CleanAir provides information about what it is, how it is impacting your wireless network, and what actions you or your network should take. It simplifies RF so that you do not have to be an RF expert.
Wireless LAN systems operate in unlicensed 2.4-GHz and 5-GHz ISM bands. Many devices, such as microwave ovens, cordless phones, and Bluetooth devices also operate in these bands and can negatively affect the Wi-Fi operations.
Some of the most advanced WLAN services, such as voice-over-wireless and IEEE 802.11 radio communications, might be significantly impaired by the interference caused by other legal users of the ISM bands. The integration of Cisco CleanAir functionality addresses this problem of RF interference.
Cisco CleanAir-Related Terms
|Air Quality Index. The AQI is an indicator of air quality, based on the air pollutants. An AQI of 0 is bad and an AQI > 85 is good.
|Air Quality Report. AQRs contain information about total interference from all the identified sources represented by AQI and the summary of the most severe interference categories. AQRs are sent every 15 minutes to the Mobility Controller and every 30 seconds in the Rapid mode.
|Duty Cycle. Percentage of time that the channel is utilized by a device.
|Event-Driven RRM. EDRRM allows an access point in distress to bypass normal RRM intervals and immediately change channels.
|Interference Device Reports that an access point sends to the controller .
|Interference Severity Index. The ISI is an indicator of the severity of the interference.
|Received Signal Strength Indicator. RSSI is a measurement of the power present in a received radio signal. It is the power at which an access point sees the interferer device.
Cisco CleanAir Components
The basic Cisco CleanAir architecture consists of Cisco CleanAir-enabled APs and device.
An access point equipped with Cisco CleanAir technology collects information about Wi-Fi interference sources and processes it. The access point collects and sends the Air Quality Report (AQR) and Interference Device Report (IDR) to the controller .
The controller controls and configures CleanAir-capable access points, and collects and processes spectrum data. The controller provides local user interfaces (GUI and CLI) to configure basic CleanAir features and services and display current spectrum information. The controller also detects, merges, and mitigates interference devices using RRM TPC and DCA For details, see Interference Device Merging.
The device performs the following tasks in a Cisco CleanAir system:
Configures Cisco CleanAir capabilities on the access point.
Provides interfaces (GUI and CLI) for configuring Cisco CleanAir features and retrieving data.
Displays spectrum data.
Collects and processes AQRs from the access point and stores them in the air quality database. AQRs contain information about the total interference from all the identified sources represented by the Air Quality Index (AQI) and the summary for the most severe interference categories. The CleanAir system can also include unclassified interference information under per-interference type reports that enable you to take action in scenarios where interference because of unclassified interfering devices is more.
Collects and processes IDRs from the access point and stores them in the interference device database.
When Cisco CleanAir is disabled and Spectrum Intelligence (SI) is enabled in the controller, both CleanAir and Air Quality reporting are disabled. In spite of this, Air Quality is still populated for SI APs and viewed as disabled when show ap dot11 5ghz/24ghz cleanair config command is executed. This is an expected behaviour as SI APs report Air Quality.
Here, Spectrum intelligence is a subset of CleanAir features. For more information on Spectrum Intelligence, see the Spectrum Intelligence Deployment Guide.
Interference Types that Cisco CleanAir can Detect
Cisco CleanAir access points can detect and report severity of the interference. Spectrum event-driven RRM is one such mitigation strategy.
Wi-Fi chip-based RF management systems share these characteristics:
Any RF energy that cannot be identified as a Wi-Fi signal is reported as noise.
Noise measurements that are used to assign a channel plan tend to be averaged over a period of time to avoid instability or rapid changes that can be disruptive to certain client devices.
Averaging measurements reduces the resolution of the measurement. As such, a signal that disrupts clients might not look like it needs to be mitigated after averaging.
All RF management systems available today are reactive in nature.
Cisco CleanAir is different and can positively identify not only the source of the noise but also its potential impact to a WLAN. Having this information allows you to consider the noise within the context of the network and make intelligent and, where possible, proactive decisions. Spontaneous interference event is commonly used for CleanAir.
Spectrum event-driven RRM can be triggered only by Cisco CleanAir-enabled access points in local mode.
Spontaneous interference is interference that appears suddenly on a network, perhaps jamming a channel or a range of channels completely. The Cisco CleanAir spectrum event-driven RRM feature allows you to set a threshold for air quality (AQ) which, if exceeded, triggers an immediate channel change for the affected access point. Most RF management systems can avoid interference, but this information takes time to propagate through the system. Cisco CleanAir relies on AQ measurements to continuously evaluate the spectrum and can trigger a move within 30 seconds. For example, if an access point detects interference from a video camera, it can recover by changing channels within 30 seconds of the camera becoming active. Cisco CleanAir also identifies and locates the source of interference so that more permanent mitigation of the device can be performed at a later time.
Microwave Ovens, Outdoor Ethernet bridges are two classes of devices that qualify as persistent, since once detected, it is likely that these devices will continue to be a random problem and are not likely to move. For these types of devices we can tell RRM of the detection and Bias the affected channel so that RRM "remembers" that there is a high potential for client impacting interference for the Detecting AP on the detected channel. For more information, see https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8-3/b_RRM_White_Paper/b_RRM_White_Paper_chapter_0100.html?bookSearch=true#id_15217.
CleanAir PDA devices include:
In the case of Bluetooth devices, Cisco CleanAir-enabled access points can detect and report interference only if the devices are actively transmitting. Bluetooth devices have extensive power-save modes. For example, interference can be detected when data or voice is being streamed between the connected devices.
EDRRM and AQR Update Mode
EDRRM is a feature that allows an access point that is in distress to bypass normal RRM intervals and immediately change channels. A CleanAir access point always monitors AQ and reports the AQ every 15 minutes. AQ only reports classified interference devices. The key benefit of EDRRM is fast action time. If an interfering device is operating on an active channel and causes enough AQ degradation to trigger an EDRRM, then no clients will be able to use that channel or the access point. You must remove the access point from the channel. EDRRM is not enabled by default, you must first enable CleanAir and then enable EDRRM.