What is dynamic frequency selection (DFS)?

Dynamic Frequency Selection (DFS) is a technique used in IEEE 802.11 wireless networks or WiFi that permits devices to dynamically switch the operating frequency of transmission in order to avoid interference with other devices.


  • DFS is a legal mandate for all IEEE 802.11 devices which share 5 GHz radio spectrum with radar.

  • DFS was adopted in IEEE 802.11h standard for wireless transmissions. It came up in 2003, when the wireless network started using 5 GHz band that is primarily used by radar systems.

  • The objective of DFS is to prevent co-channel interference of signals between the primary user, i.e. radar systems, and the secondary users, i.e. the WiFi or WLAN.

  • DFS allows a router or access point (AP) of a wireless network to detect radar signals in the same frequency spectrum, and change their operating frequency.

  • The switching of frequency prevents interference between the signals, and assures that the radar systems are able to transmit accurate signals.