In a communications apparatus first radio module communicates with a first wireless network and provides wireless communication services in compliance with a first RAT. A second radio module communicates with a second wireless network and provides wireless communication services in compliance with a second RAT. At least two antennas are shared by the first radio module and the second radio module. When the first radio module operates in an idle mode and when the timing of the first radio module performing a first receiving activity coincides with the timing of the second radio module performing a second receiving activity, the second radio module uses the antennas to perform the second receiving activity when a DRX cycle duration of the first radio module in the idle mode is shorter than a DRX cycle duration of the second radio module.