Freeradius 2.2.5 Access by SSID

Dear, I have a Debian server with Freeradius 2.2.5+dfsg-0.2, authenticating against an Active Directory server. I use PEAP / MSCHAPv2 and NTLM authentication. I have no MySQL server installed, all my config is in /etc/freeradius/* files. Everything work OK at the moment, but now I need to authenticate users by different SSID's, as below: SSID1 --> User-A and User-B SSID2 --> User-C and User-D Is this implementation possible in my current scenario? In the affirmartive case, what is the best way to do that? Thanks in advance!!! Alejandro