A communication apparatus is provided. A radio transceiver module receives paging indicators according to a first activation signal. A baseband processing module receives the paging indicators from the radio transceiver module and processes the paging indicators according to a second activation signal. A controller obtains corresponding system frame numbers of periodic radio frames, obtains a corresponding paging indicator position in each periodic radio frame, obtains a first and a second wake up time interval distributed within each periodic radio frame according to the corresponding paging indicator position, generates the first and the second activation signal to respectively activate the radio transceiver module and the baseband processing module during the first and the second wake up time interval, wherein both a length of the first wake up time interval and a length of the second wake up time interval are smaller than a length of a periodic radio frame.