An access point establishing a
wireless LAN is constructed to have a monitor
system ‘b’ for monitoring an available channel for communication, in addition to a communication
system ‘a’. In the event of detection of
radar / radio signals, the access point changes a
communication channel used for
wireless communication from a current active channel to the monitored channel. Each terminal belonging to the
wireless LAN recognizes and follows this channel change by detection of a
beacon broadcasted by the access point. In the case of non-detection of
radar / radio signals for one minute at the monitored channel, the wireless communication is reestablished immediately at the monitored channel recognized as a CAC (
channel availability check)-finished channel. This series of
processing is also applicable to inter-access point communication, for example, communication in a WDS (
wireless distribution system) mode. This arrangement desirably prevents the potential interruption of wireless communication in a 5 GHz
frequency band for a significant period, in the event of detection of
radar / radio signals, for example, a
weather radar.