With DFS, a Wi-Fi can perform an automatic channel change if another device is detected on the channel in use. another device has been detected on the channel used. This is intended in particular to prevent weather radar systems operating in this frequency range from being from being disturbed by WLANs. In order to recognise other systems, the channel must be periodically monitored. As soon as a foreign transmitter is recognised, a change of channel must be initiated immediately. The selection of the new channel is random and is usually carried out by the access point and then communicated to the other network participants. In an ad-hoc network, one of the participating stations must take over the channel selection and the organisation of the channel change. and the organisation of the channel change.
For operation in European Union, DFS must be used on channels 52 - 64 (5.25 - 5.35 GHz) and 100 - 140 (5.47 - 5.725 GHz).