design of a wireless internet access system for use at a hotel.
A hotel is like any other building only usually larger. That answer may not get the lecturer's approval (if this is a homework project) but it's true anyway. You set it up like anywhere else and only give the guests the security key when they pay you for it. Change it every week in case they come back and stay at the hotel next door so they can't poach your DSL signal because they know your key.