802.11 standard; enhancements for high-efficiency WLAN operation between 1 GHz and 7.125 GHz

An IEEE 802.11 standard that specifies modifications to the physical (PHY) layer and medium access control (MAC) sublayer for high-efficiency operation in frequency bands between 1 GHz and 7.125 GHz. 

802.11ax encompasses both Wi-Fi 6 and Wi-Fi 6E generations, which are marketed by the Wi-Fi Alliance. Wi-Fi 6 only supports 2.4 and 5 GHz and Wi-Fi 6E supports 2.4, 5, and 6 GHz.