Imagine a client device ("station" in the wifi terminology) with an authenticated, living connection to a 802.11 infrastructure. The APs are expected to follow the relevant standards.
Then, the client device goes in suspension: all of its internal state remains, but it becomes incapable for any radio communication. Essentially, it is powered off.
Being powered on again, it has all what is needed to continue the 802.11 traffic as it wants to.
How long can the communication timeout last without a requirement of a new handshake?