Methods and apparatuses for transmitting and receiving data in wireless communication system

1. A method performed by a user equipment (UE) in a wireless communication for performing handover between different radio access technologies, the method comprising:

receiving a radio resource control (RRC) message;

identifying whether a full configuration indicator is included in the RRC message;

in case that the full configuration indicator is not included in the RRC message, maintaining configuration information of a packet data convergence protocol (PDCP) layer or a service data adaptation protocol (SDAP) layer configured in a source base station (BS); and

based on the identification that the full configuration indicator is not included in the RRC message, using, for a target BS, the maintained configuration information of the PDCP layer or the SDAP layer configured in the source BS.

2. The method of claim 1 further comprising:

in case that the full configuration indicator is included in the RRC message, releasing the configuration information of the PDCP layer or the SDAP layer configured in the source BS for all bearers.

3. The method of claim 1 further comprising at least one of:

resetting media access control (MAC) layer;

stopping all timers that are running;

releasing configured security configuration information; or

releasing configuration information of a radio link control (RLC) layer or the MAC layer.

4. The method of claim 1 , wherein the RRC message comprises an RRC reconfiguration message or an RRC resume message.

5. The method of claim 1 further comprising:

identifying successful completion of the handover between the different radio access technologies.

6. The method of claim 1 , wherein the source BS is new radio (NR) and a target BS is evolved universal terrestrial radio access (E-UTRA).

7. The method of claim 1 , wherein the source BS is E-UTRA and a target BS is NR.

8. A user equipment (UE) in a wireless communication for performing handover between different radio access technologies, the UE comprising:

a transceiver;

a memory; and

at least one processor coupled with the memory and configured to:

receive a radio resource control (RRC) message;

identify whether a full configuration indicator is included in the RRC message;

in case that the full configuration indicator is not included in the RRC message, maintain configuration information of a packet data convergence protocol (PDCP) layer or a service data adaptation protocol (SDAP) layer configured in a source base station (BS); and

based on the identification that the full configuration indicator is not included in the RRC message, use, for a target BS, the maintained configuration information of the PDCP layer or the SDAP layer configured in the source BS.

9. The UE of claim 8 , the at least one processor further configured to:

in case that the full configuration indicator is included in the RRC message, release the configuration information of the PDCP layer or the SDAP layer configured in the source BS for all bearers.

10. The UE of claim 8 , the at least one processor further configured to:

reset media access control (MAC) layer;

stop all timers that are running;

release configured security configuration information; or

release configuration information of a radio link control (RLC) layer or the MAC layer.

11. The UE of claim 8 , wherein the RRC message comprises an RRC reconfiguration message or an RRC resume message.

12. The UE of claim 8 , the at least one processor further configured to:

identify successful completion of the handover between the different radio access technologies.

13. The UE of claim 8 , wherein the source BS is new radio (NR) and a target BS is evolved universal terrestrial radio access (E-UTRA).

14. The UE of claim 8 , wherein the source BS is E-UTRA and a target BS is NR.

15. A method performed by a source base station (BS) in a wireless communication for performing handover between different radio access technologies, the method comprising:

transmitting, to a user equipment (UE), a radio resource control (RRC) message including a full configuration indicator,

wherein the full configuration indicator is associated with whether the UE maintains or releases configuration information of a packet data convergence protocol (PDCP) layer or a service data adaptation protocol (SDAP) layer configured in the source BS, and

wherein the full configuration indicator is associated with whether the UE uses, for a target BS, the configuration information of the PDCP layer or the SDAP layer configured in the source BS.

16. The method of claim 15 , wherein the RRC message comprises an RRC reconfiguration message or an RRC resume message.

17. A source base station (BS) in a wireless communication for performing handover between different radio access technologies, the source BS comprising:

a transceiver;

a memory; and

at least one processor coupled with the memory and configured to:

transmit, to a user equipment (UE), a radio resource control (RRC) message including a full configuration indicator,

wherein the full configuration indicator is associated with whether the UE maintains or releases configuration information of a packet data convergence protocol (PDCP) layer or a service data adaptation protocol (SDAP) layer configured in the source BS, and

wherein the full configuration indicator is associated with whether the UE uses, for a target BS, the configuration information of the PDCP layer or the SDAP layer configured in the source BS.

18. The source BS of claim 17 , wherein the RRC message comprises an RRC reconfiguration message or an RRC resume message.