Companies do rent convention centers for yearly events all the time. However, most convention centers do not offer some of the services needed to run a successful large scale event. For instance, if you are going to need displays, tablets, stands, high bandwidth internet etc., those are the types of services that you will most likely need an outside vendor for.
Luckily, there are companies that provide wifi service for a convention center that you can get in touch with. First thing that you need to do is to come up with how many attendees you will be expecting for this event and what type of bandwith you think they will require. If they are mostly going to be using email and social media, the need may not be that high, however, if they will be doing bandwidth intensive stuff such as watching videos, downloading / uploading files etc., you will need to be more careful about the needed bandwidth.
Another thing to keep an eye out for will be to make sure that the wifi service you are getting will not have any dead spots at the convention center of your choice. This could cause major headaches if some of the attendees seated at different parts of the convention center cannot access internet.
Make sure to pick the right wifi service vendor for your needs so you can focus on your events and your attendees to ensure a successful event execution.