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Band Steering is a solution ensures that clients are connected to the best radio. Dual Band supported Gateway can transmit SSIDs in both 2.4GHz and 5GHz frequency band. Band Steering solution does upgrade steering ( from 2.4 GHz to 5 GHz) and downgrade steering (5 GHz to 2.4 GHz) which allows optimal utilization of both bands. The Steering of the Wireless clients are based on the following parameter,
The purpose of Band Steering feature is to maintain Wireless Clients in band best suited to them. For instance, a 5GHz capable client would be maintained in faster & wider-channeled 5GHz band but if the Received Signal Strength is lesser than the threshold value, the Client is moved to a wider-range 2.4GHz band.
The most basic prerequisite of Band Steering is both the 2.4GHz and the 5GHz frequency band must have the same SSID and passphrase. The wireless Clients will be steered to a better band only if SSID and password are same. So before performing Band Steering operations, same SSID, Authentication Mechanism and passphrase are set to both 2.4GHz and 5GHz band. The enable & disabling of the Band Steering feature is done by dmcli command. Changes are done in WiFiHal and meta-cmf-raspberypi layer.
Modified Wifi Hal APIs related to Band Steering are as follows,
On Enabling, checks if the Device is dual band capable and makes sure that the SSID, passphrase and Authentication mechanism is same in both 2.4GHz and 5GHz. Sets syscfg value for "band_steering_enable" as "1"
When disabled, resets the configured SSIDs, passphrase and Authentication Mechanism in 5GHz band. Also sets syscfg value for "band_steering_enable" as "0".
Returns the Band Steering status of the device, this is done by using the syscfg get "band_steering_enable" variable.
Returns true if the device can transmit SSID in both 2.4GHz and 5GHz band, else return false. The return type is the device capability to support Band Steering Feature.
A compilation flag is defined to include WiFi Band Steering related calls in the CcspWifiAgent component.
System default is added with name "band_steering_enable" to track band steering status, whether enabled/disbaled.
Pre-association Band steering:
a. When SNR of client received by AP/Gateway in 2.4GHz band is more than the threshold, then AP blocks the 2.4GHz band for the client and informs client to probe request to 5GHz.
b. If the client device continues to probe request to 2.4GHz band, AP blocks the response in 2.4GHz until client device is ready to connect to 5GHz.
c. Sometimes client devices continues to probe request to 2.4GHz though AP blocks its response, in this case, after blocking a considerable number of times during a time period, AP enters backs off period and allows client to connect to 2.4GHz. For this period, AP does not try to steer the client to 5GHz again.
Post-association Band Steering:
a. Client has associated with a non-preferred band, SNR is checked if it is above threshold. If it is above threshold, client is disassociated from the band and Steered to preferred band using Pre-association procedure.
Architecture
S.no | Module | dmcli command | Description |
---|---|---|---|
1 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.Enable | used to enabled/disbaled Band Steering |
2 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.APGroup | sets/returns AP Group name |
3 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.Capability | returns Band Steering Device level capability |
4 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.History | History of Clients Steered across bands |
5 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.<radio-index>.UtilizationThreshold | Bandwidth Utilization threshold for 2.4/5 GHz |
6 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.<radio-index>.RSSIThreshold | Signal Strength threshold for 2.4/5 GHz |
7 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.<radio-index>.PhyRateThreshold | Physical Transmit rate thresholdrate for a Client in a band |
8 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.<radio-index>.OverloadInactiveTime | Threshold inactive time of a client during band overload condiiton |
9 | WiFi - TR181-WiFi-USGv2.XML | Device.WiFi.X_RDKCENTRAL-COM_BandSteering.<radio-index>.IdleInactiveTime | Threshold inactive time of a client during Idle condiiton |