Method and apparatus for handling cell selection and re-selection in MR-DC system

1. A method for handling cell selection in a multiple radio access technology (RAT)—dual connectivity (DC)(MR-DC) system, comprising

scanning, by a user equipment (UE), at least one frequency;

obtaining, by the UE, at least one message;

determining, by the UE, a first cell supporting the MR-DC to camp to among at least one cell corresponding to the scanned at least one frequency respectively, based on the Obtained at least one message, by prioritizing a cell supporting an evolved-universal terrestrial radio access (E-UTRA) new radio (NR)—dual connectivity (DC) (EN-DC) among the at least one cell; and

camping, by the UE, to the determined first cell.

2. The method of claim 1 , further comprising storing, by the UE, at least one of MR-DC support information and 5th generation core (5GC) network connectivity support information corresponding to each of the scanned at least one frequency.

3. The method of claim 1 , further comprising:

storing, by the UE, first information corresponding to the first cell in response to determining that the first cell supporting the MR-DC, and

storing, by the UE, second information corresponding to a second cell in response to detecting the second cell supporting the MR-DC,

wherein the first information includes a type of the first cell and a frequency value of the first cell, and the second information includes a type of the second cell and a frequency value of the second cell.

4. The method of claim 1 , wherein the at least one message comprises a system information block 1 (SIB1) message,

wherein determining, by the UTE, the first cell to camp to further comprises determining, by the UE, whether the first cell supports a 5th generation core (5GC) network connectivity based on an information element (IE) in the SIB1 message, and

wherein frequency information related to the first cell, the public land mobile network (PLMN) information related to the first cell, and 5GC network connectivity support information of the first cell are stored in the UE.

5. The method of claim 1 , wherein the at least one message comprises a system information block 2 (SIB1) message,

wherein determining, by the UE, the first cell to camp to further comprises identifying, by the UTE, a type of the MR-DC based on an MR-DC availability indication included in the SIB 2 message, and

wherein the type of the MR DC comprises one of a next generation (NG) radio access network (RAN) evolved-universal terrestrial radio access (E-UTRA) new radio (NR)—dual connectivity (DC)(NGEN-DC) and an E-UTRA new radio (NR)—DC (EN-DC).

6. The method of claim I, wherein the at least one message comprises a system information block 1 (SIB1) message,

wherein determining, by the UE, the first cell to camp to further comprises determining, by the LE, whether the first cell supports the MR-DC based on an information element (IE) in the SIB1 message, and

wherein a type of the MR DC comprises new radio (NR) evolved-universal terrestrial radio access (E-UTRA)—dual connectivity (DC)(NE-DC).

7. The method of claim 1 , wherein the first cell and a second cell are long-term evolution (LTE) cells if the UE is in at least one of an evolved-universal terrestrial radio access (E-UTRA) new radio (NR)—DC (EN-DC) architecture and a next generation (NG) radio access network (RAN) E-UTRA NR—DC (NGEN-DC) architecture, and

wherein the first cell and the second cell are new radio (NR) cells having DC to an LTE, if the UE is in an NR E-UTRA—DC (NE-DC) architecture.

8. The method of claim 1 , wherein the at least one message comprises one of a system information block 1 (SIB1) message and an SIB2 message.

9. The method of claim 1 , further comprising determining the second cell to camp supporting the MR-DC,

wherein determining the second cell comprises:

identifying, by the UE, MR-DC support information or 5th generation core (5GC) network support information for a plurality of cells; and

selecting, by the UE, the second cell supporting the MR-DC from the plurality of cells based on the identified MR-DC support information or the 5GC support information.

10. A user equipment (UE) for handling cell selection in a multiple radio access technology (RAT)—dual connectivity (DC) (MR-DC) system, comprising:

a memory; and

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

scan at least one frequency,

obtain at least one message,

determine a first cell supporting the MR-DC to camp to among at least one cell corresponding to the scanned at least one frequency respectively, based on the obtained at least one message, by prioritizing a cell supporting an evolved-universal terrestrial radio access (E-UTRA) new radio (NR)—dual connectivity (DC) (EN-DC) among the at least one cell, and

camp to the determined first cell.

11. The UE of claim 10 , wherein the at least one processor is further configured to control the memory to store at least one of MR-DC support information and 5th generation core (5GC) network connectivity support information corresponding to each of the scanned at least one frequency.

12. The UE of claim 10 , wherein the at least one processor is further configured to control the memory to:

store first information corresponding to the first cell in response to determining that the first cell supporting the MR-DC, and

store second information corresponding to a second cell in response to detecting the second cell supporting the MR-DC,

wherein the first information includes a type of the first cell and a frequency value of the first cell, and the second information includes a type of the second cell and a frequency value of the second cell.

13. The LTE of claim 10 , wherein the at least one message comprises a system information block 1 (SIB1) message,

wherein the at least one processor is further configured to determine whether the first cell supports a 5th generation core (5GC) network connectivity based on an information element (IE) in the SIB1 message, and

wherein frequency information related to the first cell, the public land mobile network (PLMN) information related to the first cell, and 5GC network connectivity support information of the first cell are stored in the UE.

14. The UE of claim 10 , wherein the at least one message comprises a system information block 2 (SIB2) message,

wherein the at least one processor is further configured to identify a type of the MR-DC based on an MR-DC availability indication included in the SIB2 message, and

wherein the type of the MR DC comprises one of a next generation (NG) radio access network (RAN) evolved-universal terrestrial radio access (E-UTRA) new radio (NR)—DC(NGEN-DC) and an E-UTRA new radio (NR)—DC (EN-DC).

15. The UE of claim 10 wherein the at least one message comprises a system information block 1 (SIB1) message,

wherein the at least one processor is further configured to determine whether the first cell supports the MR-DC based on an information element (IE) in the SIB1 message, and

wherein a type of the MR DC comprises new radio (NR) evolved-universal terrestrial radio access (E-UTRA)—dual connectivity (DC)(NE-DC).

16. The UE of claim 10 , wherein the first cell and a second cell are long-term evolution (LTE) cells if the UE is in at least one of an evolved-universal terrestrial radio access (E-UTRA) new radio (NR)—DC (EN-DC) architecture and a next generation (NG) radio access network (RAN) E-UTRA NR—DC (NGEN-DC) architecture, and

wherein the first cell and the second cell are new radio (NR) cells having DC to an LTE, if the UE is in an NR E-UTRA—DC (NE-DC) architecture.

17. The UE of claim 10 , wherein the at least one message comprises one of a system information block 1 (SIB1) message and an SIB2 message.

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

identify MR-DC support information or 5 th generation core (5GC) network support information for a plurality of cells, and

select a second cell to camp to supporting the MR-DC from the plurality of cells based on the MR-DC support information or the 5GC support information.