A communication apparatus, comprising: a radio frequency signal processing device, for transmitting and receiving an RF signal and processing the RF signal in accordance with a predetermined protocol to generate a first signal; a baseband signal processing device, coupled to the RF signal processing device, for processing the first signal; and an access control module, for controlling operations of the communication apparatus in at least a station mode and an access point mode, wherein in the AP mode, the communication apparatus is operative to provide a network access service for one or more peer device(s) associated therewith, and wherein the access control module issues a first indication signal and a second indication signal under the AP mode so that the RF signal processing device and the baseband signal processing device are switched between a first power level and a second power level in the AP mode, wherein in the first power level, the RF signal processing device and the baseband signal processing device are turned off, and the transmission and reception of the RF signal and the processing of the RF signal and the first signal are suspended, wherein the baseband signal processing device further detects whether a communication channel is busy or not and reports a detection result to the access control module when being switched to the second power level, characterized in that a duration of a switching cycle of the RF signal processing device and the baseband signal processing device is shorter than a duration of transmitting one physical layer convergence procedure (PLCP) protocol data unit (PPDU). a radio frequency signal processing device, for transmitting and receiving an RF signal and processing the RF signal in accordance with a predetermined protocol to generate a first signal; a baseband signal processing device, coupled to the RF signal processing device, for processing the first signal; and an access control module, for controlling operations of the communication apparatus in at least a station mode and an access point mode, wherein in the AP mode, the communication apparatus is operative to provide a network access service for one or more peer device(s) associated therewith, and wherein the access control module issues a first indication signal and a second indication signal under the AP mode so that the RF signal processing device and the baseband signal processing device are switched between a first power level and a second power level in the AP mode, wherein in the first power level, the RF signal processing device and the baseband signal processing device are turned off, and the transmission and reception of the RF signal and the processing of the RF signal and the first signal are suspended, wherein the baseband signal processing device further detects whether a communication channel is busy or not and reports a detection result to the access control module when being switched to the second power level, characterized in that a duration of a switching cycle of the RF signal processing device and the baseband signal processing device is shorter than a duration of transmitting one physical layer convergence procedure (PLCP) protocol data unit (PPDU).