Drag the 802.11 functional responsibility in the Cisco "Split MAC" design from the left and drop it on a platform on the right:

beacons encryption/decryption transmission and buffering of frames 802.11 association and re-association client authentication RF management

Access Point beacons Access Point encryption/decryption Access Point transmission and buffering of frames Controller 802.11 association and re-association Controller client authentication Controller RF management