you can use QoS roles:
This will only affect downstream, not upstream traffic.
You want to say "Thank you"?
Don't. Just rate the useful answers,
that is more useful than "Thank you".
There is some kind of bandwidth control for ssid guest on the WLC?
Depends on what firmware your controller is running.
If you have the new 7.3.X then you now have the options of either configuring bandwidth control on a per-SSID basis or per-user basis.