Device and method of handling aggregation of cellular network and wireless local area network

A communication device of handling aggregation of cellular network and Wireless Local Area Network (WLAN) (CWA), comprising:

• a storage device;
• and
• a processing circuit, coupled to the storage device, wherein the storage device stores, and the processing circuit is configured to execute instructions of:
• configuring a transmitting window to a Packet Data Convergence Protocol (PDCP) entity of a radio bearer, when the radio bearer is a CWA bearer;
• releasing a PDCP PDU transmitted by the PDCP entity, when receiving a cellular acknowledgement indicating that the PDCP PDU is received and the PDCP PDU is outside the transmitting window;
• and
• shifting the transmitting window, when a first PDCP PDU with a lowest sequence number in the transmitting window transmitted by the PDCP entity is acknowledged by a WLAN Medium Access Control (MAC) acknowledgement and a second PDCP PDU enters the transmission window, wherein the second PDCP PDU is outside the transmitting window.

A communication device of handling aggregation of cellular network and Wireless Local Area Network (WLAN) (CWA), comprising:

• a storage device;
• and
• a processing circuit, coupled to the storage device, wherein the storage device stores, and the processing circuit is configured to execute instructions of:
• transmitting a message indicating support of the CWA to a base station (BS) via a cellular connection;
• receiving a configuration message configuring the CWA from the BS via the cellular connection;
• transmitting a plurality of cellular protocol data units (PDUs) to a WLAN configured by the configuration message via a WLAN connection;
• receiving a status report indicating that a first cellular PDU of the plurality of cellular PDUs is lost from the BS;
• transmitting the first cellular PDU indicated by the status report, when the communication device has the first cellular PDU in a memory device of the communication device;
• ignoring the first cellular PDU, when the communication device does not have the first cellular PDU in the memory device;
• and
• ignoring the status report when all of lost LTE PDUs indicated by the status report are not in the memory device.