Simbhu,
The Guest Portal lives on the controller, so if you're wanting to use it, the controller will have to be active.
If you wanted to use some sort of other external portal/authentication means (i.e. NAC), once the AP is configured, you could, in theory turn off the V2110 controller, as the settings & filters would be downloaded to the AP.
Is there a reason why the controller cannot stay active? If you have an older computer, you may be able to just have it run the controller; it's not very resource intensive.
Thanks,
Bill