Dynamic channel selection and DFS re-entry

A wireless network device (for example an Access Point, or base station) for operation in a wireless network (for example a Wi-Fi network) comprises a wireless interface operable on one or more wireless channels, a memory, a processor configured to scan at least one channel for a predetermined time duration and make a channel quality assessment measurement during the predetermined time duration. The processor is adapted to synchronize the predetermined time duration with other wireless network devices that are operable in the wireless network and that scan the at least one channel and make channel quality assessment measurements during substantially the same predetermined time duration. The channel quality assessment measurement is compared with others from other network devices that are operable in the wireless network thereby to enable determination of an optimal channel for communication between the network devices. The channel quality assessment may consist of a Clear Channel Assessment CCA. An embodiment describes detecting channels which are unavailable due to RADAR systems operating on the channel, and in particular, detecting periods within a day when said channels are unavailable due to Radar activity.