SWRU423A July 2015 – May 2016 WL1801MOD , WL1805MOD , WL1807MOD , WL1831MOD , WL1835MOD , WL1837MOD
The dynamic frequency selection (DFS) channels are 5-GHz channels, 52 to 140, where radar can operate. Channel switch is a mechanism implemented to avoid co-channel operation with radar systems. This feature verifies that the STA does not transmit any packets in DFS channels upon radar detection.
The AP is the master and must detect the radar and notify the client-slave that should get the info from the AP. The AP informs associated STAs that the AP is moving to a new channel and maintains the association by advertising the switch using channel switch announcement elements (IE#37) in beacon frames, probe response frames, and channel switch announcement frames, until the intended channel switch time. The AP may force STAs in the BSS to stop transmissions until the channel switch takes place, by setting the channel switch mode field in the channel switch announcement element to 1.
The channel switch should be scheduled so that all STAs in the BSS, including STAs in power-save mode, have the opportunity to receive at least one channel switch announcement element before the switch. An STA that receives a channel switch announcement element can choose not to perform the specified switch and take alternative action instead. For example, it can choose to move to a different BSS. An STA in a BSS that is not the AP must not transmit the channel switch announcement element.