Methods for re-synchronizing a communication mode with a peer device and communications apparatus utilizing the same

A communications apparatus, comprising:

• a radio transceiver, transmitting or receiving wireless radio frequency signals to or from a peer device;
• and a processor, determining whether re-synchronization in a communication mode with the peer device is required according to a determination rule, and when the re-synchronization is required, transmitting a message to the peer device via the radio transceiver to trigger a re-synchronization procedure, wherein the processor determines whether the re-synchronization is required in a connected mode, wherein the connected mode is entered after the processor has set up a radio resource control (RRC) connection with the peer device and transmitted a connection setup complete message to the peer device in response to reception of a first paging message, and
• wherein the processor further starts a first timer when the connected mode is entered, and when a second paging message, which comes after the first paging message and with same Cn-Domain field as the first paging message, is received from the peer device before the first timer expires, the processor ignores the second paging message and does not process or respond to the second paging message, wherein the processor further starts a second timer when transmitting the message to the peer device to trigger the re-synchronization procedure, and when another paging message is received from the peer device before the second timer expires, the processor ignores the paging message.