Which IEEE standard enables Fast BSS Transition (FT) for seamless roaming?

802.11k provides radio resource management and neighbor AP reports to help clients discover roaming candidates faster, but it does not define the fast authentication mechanism itself.

802.11r introduces the Fast Transition protocol, which caches security keys at neighboring APs via a mobility domain, allowing a client to complete re-authentication in a single exchange instead of the full 802.1X/EAP handshake. This reduces roaming latency from hundreds of milliseconds to under 50 ms, enabling seamless connectivity during movement. Without 802.11r, voice and video calls are frequently disrupted during AP transitions.

802.11v defines BSS Transition Management, which allows the network to suggest or request that a client roam to a different AP, but it does not accelerate the authentication handshake.

802.11ac (now called Wi-Fi 5) is a physical and MAC layer standard focused on high-throughput transmission in the 5 GHz band and has no relation to roaming authentication procedures.