Method for processing data in consideration of TCP/IP

A packet processing method of a receiving device in a wireless communication system, the method comprising:

• identifying whether a data radio bearer (DRB) mapped to a quality of service (QoS) flow is changed from a legacy DRB to a new DRB;
• and
• receiving, from a transmitting device via the new DRB, information on a last packet transmitted from the transmitting device to the receiving device on the legacy DRB in the QoS flow in case that the DRB is changed from the legacy DRB to the new DRB,
• wherein the information on the last packet transmitted from the transmitting device to the receiving device on the legacy DRB includes a sequence number of the last packet on the legacy DRB.

A transmitting device for processing packets in a wireless communication system, the device comprising:

• a transceiver;
• and
• a controller connected to the transceiver and configured to control to:
• identify whether a data radio bearer (DRB) mapped to a quality of service (QoS) flow is changed from a legacy data radio bearer (DRB) to a new DRB;
• and
• transmit information, to a receiving device via the new DRB, on a last packet being transmitted from the transmitting device to the receiving device on the legacy DRB in the QoS flow in case that the DRB is changed from the legacy DRB to the new DRB,
• wherein the information on the last packet transmitted from the transmitting device to the receiving device on the legacy DRB includes a sequence number of the last packet on the legacy DRB.

A receiving device for processing packets in a wireless communication system, the device comprising:

• a transceiver;
• and
• a controller connected to the transceiver and configured to control to:
• identify whether a data radio bearer (DRB) mapped to a quality of service (QoS) flow is changed from a legacy DRB to a new DRB;
• and
• receive, from a transmitting device via the new DRB, information on a last packet being transmitted from the transmitting device to the receiving device on the legacy DRB in the QoS flow in case that the DRB is changed from the legacy DRB to the new DRB,
• wherein the information on the last packet transmitted from the transmitting device to the receiving device on the legacy DRB includes a sequence number of the last packet on the legacy DRB.