Method and apparatus for PLMN selection and cell (re)selection

1. A User Equipment (UE), comprising:

one or more non-transitory computer-readable media having computer-executable instructions embodied thereon; and

at least one processor coupled to the one or more non-transitory computer-readable media, and configured to execute the computer-executable instructions to:

read system information of a plurality of cells on a first carrier frequency to obtain identification information of a plurality of Public Land Mobile Networks (PLMNs), the first carrier frequency being an unlicensed carrier frequency;

report, by an Access Stratum (AS) entity of the UE, the identification information of the plurality of PLMNs to a Non-Access Stratum (NAS) entity of the UE;

select, by the NAS entity of the UE, one of the plurality of PLMNs as a selected PLMN;

search for the plurality of cells on the first carrier frequency during a cell selection procedure;

select a suitable cell belonging to the selected PLMN from the plurality of cells on the first carrier frequency as an outcome of the cell selection procedure; and

perform a cell reselection procedure to select a new suitable cell, the cell reselection procedure comprising:

determining whether a highest-ranked cell on the first carrier frequency belongs to one of the selected PLMN and a PLMN that is indicated as being equivalent to a registered PLMN of the UE;

selecting the highest-ranked cell as the new suitable cell when the highest-ranked cell belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE; and

when the highest-ranked cell is not selected as the new suitable cell,

prohibiting the highest-ranked cell from being selected as the new suitable cell for a first period of time, and

iteratively performing a process on the first carrier frequency, until the new suitable cell is found on the first carrier frequency or a specific number of cells on the first carrier frequency are determined as non-suitable, the process comprising:

 determining whether a next highest-ranked cell on the first carrier frequency belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE;

 selecting the next highest-ranked cell as the new suitable cell when the next highest-ranked cell belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE; and

 determining that the next highest-ranked cell is non-suitable when the next highest-ranked cell is not selected as the new suitable cell.

2. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

search for the new suitable cell on a second carrier frequency when a total number of non-suitable cells on the first carrier frequency reaches the specific number.

3. The UE of claim 2 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

determine whether another highest-ranked cell on the second carrier frequency belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE;

select the another highest-ranked cell as the new suitable cell when the another highest-ranked cell belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE; and

when the another highest-ranked cell on the second carrier frequency is not selected as the new suitable cell, prohibit the another highest-ranked cell from being selected as the new suitable cell for a second period of time,

wherein a length of the second period of time is independent of a length of the first period of time.

4. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

deprioritize the first carrier frequency in a set of carrier frequencies for the cell reselection procedure for a second period of time when a total number of non-suitable cells on the first carrier frequency reaches the specific number.

5. The UE of claim 1 , wherein the highest-ranked cell and the next highest-ranked cell on the first carrier frequency are ranked by a received radio signal quality, and the next highest-ranked cell has a poorer received radio signal quality than the highest-ranked cell.

6. The UE of claim 1 , wherein the highest-ranked cell and the next highest-ranked cell belong to two different PLMNs of the plurality of PLMNs.

7. The UE of claim 1 , wherein the system information includes PLMN type information indicating at least one PLMN type associated with the plurality of cells.

8. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

provide a message by the NAS entity of the UE to the AS entity of the UE, the message indicating which of one or more PLMN types are supported by the UE,

wherein the one or more PLMN types include at least one of a public PLMN type, a private PLMN type, and a public and private PLMN type.

9. A method of wireless communications, the method comprising:

reading, by a User Equipment (UE), system information of a plurality of cells on a first carrier frequency to obtain identification information of a plurality of Public Land Mobile Networks (PLMNs), the first carrier frequency being an unlicensed carrier frequency;

reporting, by an Access Stratum (AS) entity of the UE, the identification information of the plurality of PLMNs to a Non-Access Stratum (NAS) entity of the UE;

selecting, by the NAS entity of the UE, one of the plurality of PLMNs as a selected PLMN;

searching, by the UE, for the plurality of cells on the first carrier frequency during a cell selection procedure;

selecting, by the UE, a suitable cell belonging to the selected PLMN from the plurality of cells on the first carrier frequency as an outcome of the cell selection procedure; and

performing, by the UE, a cell reselection procedure to select a new suitable cell, the cell reselection procedure comprising:

determining whether a highest-ranked cell on the first carrier frequency belongs to one of the selected PLMN and a PLMN that is indicated as being equivalent to a registered PLMN of the UE;

selecting the highest-ranked cell as the new suitable cell when the highest-ranked cell belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE; and

when the highest-ranked cell is not selected as the new suitable cell,

prohibiting the highest-ranked cell from being selected as the new suitable cell for a first period of time, and

iteratively performing a process on the first carrier frequency, until the new suitable cell is found on the first carrier frequency or a specific number of cells on the first carrier frequency are determined as non-suitable, the process comprising:

determining whether a next highest-ranked cell on the first carrier frequency belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE;

selecting the next highest-ranked cell as the new suitable cell when the next highest-ranked cell belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE; and

determining that the next highest-ranked cell is non-suitable when the next highest-ranked cell is not selected as the new suitable cell.

10. The method of claim 9 , further comprising:

searching, by the UE, for the new suitable cell on a second carrier frequency when a total number of non-suitable cells on the first carrier frequency reaches the specific number.

11. The method of claim 10 , further comprising:

determining, by the UE, whether another highest-ranked cell on the second carrier frequency belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE;

selecting, by the UE, the another highest-ranked cell as the new suitable cell when the another highest-ranked cell belongs to one of the selected PLMN and the PLMN that is indicated as being equivalent to the registered PLMN of the UE; and

when the another highest-ranked cell on the second carrier frequency is not selected as the new suitable cell, prohibiting, by the UE, the another highest-ranked cell from being selected as the new suitable cell for a second period of time,

wherein a length of the second period of time is independent of a length of the first period of time.

12. The method of claim 9 , further comprising:

deprioritizing, by the UE, the first carrier frequency in a set of carrier frequencies for the cell reselection procedure for a second period of time when a total number of non-suitable cells on the first carrier frequency reaches the specific number.

13. The method of claim 9 , wherein the highest-ranked cell and the next highest-ranked cell on the first carrier frequency are ranked by a received radio signal quality, and the next highest-ranked cell has a poorer received radio signal quality than the highest-ranked cell.

14. The method of claim 9 , wherein the highest-ranked cell and the next highest-ranked cell belong to two different PLMNs of the plurality of PLMNs.

15. The method of claim 9 , wherein the system information includes PLMN type information indicating at least one PLMN type associated with the plurality of cells.

16. The method of claim 9 , further comprising:

providing, by the NAS entity of the UE, a message to the AS entity of the UE, the message indicating which of one or more PLMN types are supported by the UE,

wherein the one or more PLMN types include at least one of a public PLMN type, a private PLMN type, and a public and private PLMN type.