Limiting Wifi Access

Hi guys, We're trying to centralize our corporate wifi authentication using freeradius. So far, I was able to get user to authenticate based on NAS IP (I got access to multiple NAS working as well) and Mac Address. Is it possible to also limit their access per SSID? The reason for this is because one of our locations, our HQ, has 3 SSID and only certain people have access to certain SSID but I'm not sure if this will conflict with already working NAS checking. Our HQ is using Cisco Wireless LAN Controller so all 3 SSID will connect to radius using the same NAS IP. Cheers, Roy Kartadinata