Systems, devices, apparatus and methods, including computer programs encoded on storage media, are disclosed for an access point (AP) in a basic service set (BSS) to advertise or indicate 320 MHz bandwidth operation and frequency segment composition in the 320 MHz bandwidth to one or more stations (STAs) in a Wireless Local Area Network (WLAN). Also, a WLAN device may advertise or indicate its 320 MHz bandwidth support capability to other WLAN devices in the WLAN.