If you're familiar with the advanced tab while configuring a WLAN on a Cisco (Airespace) WLC, you've probably seen the Session Timeout checkbox and corresponding timer value.
This timer is used to setup how long a wireless user can remain connected before reauthentication is required.
While deploying a 5760 to match an existing 4400 controller, I attempted to disable the session timeout, but to no avail. Let's look at my simple WLAN I have configured: