Dynamic Frequency Selection (DFS) is a technique employed by radio transmitters to prevent interference by avoiding the use of channels that are already in use. Periodically, the radio transmitter monitors its local radio environment, identifying channels that are currently occupied. Utilizing this information, the transmitter selects an operating frequency that is currently available to minimize the risk of interference. DFS can be categorized as a form of Adaptive Frequency Agility (AFA).

DFS proves to be highly valuable in scenarios where a frequency band must be shared among a substantial number of users or when the band is shared with another service that takes precedence.

For instance, DFS is commonly utilized in cordless telephones, such as DECT (Digital Enhanced Cordless Telecommunications), to identify unoccupied channels for communication. Additionally, Radio LANs operating in the 5 GHz band employ DFS to prevent interference with radar systems operating within the same frequency band. This dynamic channel selection mechanism helps maintain efficient and interference-free communication in such wireless environments.