WPA2 is a certification created by the Wi-Fi Alliance that validates devices correctly implement CCMP/AES. The Wi-Fi Alliance developed WPA2 to ensure interoperability and security in wireless networks, and it implements CCMP/AES for enhanced security measures over previous standards.
The correct channel that became available in the 802.11-2016 standard that was not available before the ratification of 802.11ac is 144. This channel was added in the updated standards for use in the 5 GHz frequency band.