Reason why there are 2 waves for 802.11AC:

The IEEE 802.11ac standard was introduced to the market in a series of
“waves” (releases) of new products and technology. The
reason is that the capabilities in 802.11ac are numerous, and delivering
them in waves allows the industry to take advantage of many without having
to wait for all capabilities to be available.

 

Note: EnGenius 802.11AC Wave 2 Access Points do not support 160MHz
Channel Bandwidth