Cisco recently released Aironet 1700 series access points which support high speed WiFi IEEE 802.11ac. One of the key specifications of this 1700 series – they “only” work with Cisco Unified Wireless Network Software Release 8.0 or later.
It’s now time to upgrade your WLC to version 8.x to get this work for you.
Here is the latest APs & WLCs software compatibility matrix (as of December 15, 2014) –
Details @ http://www.cisco.com/c/en/us/td/docs/wireless/compatibility/matrix/compatibility-matrix.html