IEEE 802.11-based Wi-Fi networks operate in the unlicensed spectrum of the 5GHz band, which is also shared by other radio devices like weather, civilian and military radars. As a result, Wi-Fi networks operating in specific 5GHz bands are required to monitor for the presence of radar activity. When emissions from radar systems are detected, clients and devices associated with Wi-Fi access points (APs) dynamically switch to a new operating channel.
Generally, DFS provides a better user experience, especially in dense deployments where multiple neighboring Wi-Fi APs are present. Increased availability of channels means there is less probability of interference between neighboring AP’s — resulting in increased performance. This is analogous to adding more lanes to a congested freeway, helping to improve traffic flow.