A pre-scan interval including three states is employed to synchronize access points and facilitate
power control to facilitate initial channel selection where a group of nearby access point are contemporaneously initialized. In State 1 the access point is operable to transmit pre-scan frames which include device ID, and to listen for pre-scan frames transmitted by other access points. When a pre-scan frame is received, the received
power level and device ID are noted and used to construct a table. The access point normally remains in State 1 until a minimum number of frame samples have been received from each access point that has been heard, and a minimum pre-
scan time has elapsed. State 2 provides synchronization of transition of the access points between State 1 and State 3. When the access point is in State 2, it transmits pre-scan frames with a
sync-mark bit set to indicate that the access point is in State 2. The access point continues to listen for pre-scan frames from other access points to determine whether those access points have transitioned to State 2, i.e., by reading the
sync-mark bit in the received frames. The access point normally transitions to State 3 when all detected access points have transmitted pre-scan frames with the
sync-mark bit set, i.e., when all detected access points have signaled readiness to move to State 3. In State 3 the access point begins a
countdown to transition to the scan interval. While counting down, the access point transmits pre-scan frames which advertise the state of the
countdown timer, and listens for pre-scan frames from other access points. If differences in the
countdown state are detected then the access points re-synchronize by adopting the countdown state of the slowest
clock.