UE-assistance to support multiple systems based on frequency band combinations

1. A method comprising:

transmitting, by a wireless device to a first base station of a first public land mobile network (PLMN), a first radio resource control (RRC) message during an RRC connection with the first base station;

selecting, during the RRC connection with the first base station, a cell of a second base station of a second PLMN for monitoring one or more downlink channels;

determining that the wireless device is not capable of communicating with the first base station during a duration for communication via the cell of the second base station; and

transmitting, to the first base station during the RRC connection with the first base station, a second RRC message indicating the duration.

2. The method of claim 1 , wherein the first RRC message indicates one or more first frequency band combinations of the first base station that the wireless device is capable of communicating with the first base station.

3. The method of claim 2 , wherein the one or more first frequency band combinations comprise a band comprising a frequency of the cell.

4. The method of claim 1 , wherein the cell operates within one or more operating frequency bands of the second base station.

5. The method of claim 2 , wherein the determining is based on the one or more first frequency band combinations of the wireless device and one or more operating frequency bands of the second base station.

6. The method of claim 2 , wherein the determining is based on:

one or more operating frequency bands of the cell;

the one or more first frequency band combinations; and

radio transceiver capability of the wireless device.

7. The method of claim 1 , wherein the duration comprises one or more combinations of periodicities and offsets.

8. The method of claim 2 , wherein the one or more first frequency band combinations comprise one or more second frequency band combinations.

9. The method of claim 4 , further comprising determining the one or more operating frequency bands of the cell, wherein:

the wireless device uses same RF chain(s) between one or more second cells of the first base station and the cell of the second base station; and

the one or more second cells of the first base station operate in the one or more operating frequency bands.

10. The method of claim 1 , wherein the one or more downlink channels are transmitted at least for paging indication from the second base station.

11. A wireless device comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the wireless device to:

transmit, to a first base station of a first public land mobile network (PLMN), a first radio resource control (RRC) message during an RRC connection with the first base station;

select, during the RRC connection with the first base station, a cell of a second base station of a second PLMN for monitoring one or more downlink channels;

determine that the wireless device is not capable of communicating with the first base station during a duration for communication via the cell of the second base station; and

transmit, to the first base station during the RRC connection with the first base station, a second RRC message indicating the duration.

12. The wireless device of claim 11 , wherein the first RRC message indicates one or more first frequency band combinations of the first base station that the wireless device is capable of communicating with the first base station.

13. The wireless device of claim 12 , wherein the one or more first frequency band combinations comprise a band comprising a frequency of the cell.

14. The wireless device of claim 11 , wherein the cell operates within one or more operating frequency bands of the second base station.

15. The wireless device of claim 12 , wherein the determining is based on the one or more first frequency band combinations of the wireless device and one or more operating frequency bands of the second base station.

16. The wireless device of claim 12 , wherein the determining is based on:

one or more operating frequency bands of the cell;

the one or more first frequency band combinations; and

radio transceiver capability of the wireless device.

17. The wireless device of claim 11 , wherein the duration comprises one or more combinations of periodicities and offsets.

18. The wireless device of claim 14 , wherein the instructions further cause the wireless device to determine the one or more operating frequency bands of the cell, wherein:

the wireless device uses same RF chain(s) between one or more second cells of the first base station and the cell of the second base station; and

the one or more second cells of the first base station operate in the one or more operating frequency bands.

19. The wireless device of claim 11 , wherein the one or more downlink channels are transmitted at least for paging indication from the second base station.

20. A system comprising:

a first base station;

a second base station; and

a wireless device comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the wireless device to:

transmit, to the first base station of a first public land mobile network (PLMN), a first radio resource control (RRC) message during an RRC connection with the first base station;

select, during the RRC connection with the first base station, a cell of the second base station of a second PLMN for monitoring one or more downlink channels;

determine that the wireless device is not capable of communicating with the first base station during a duration for communication via the cell of the second base station; and

transmit, to the first base station during the RRC connection with the first base station, a second RRC message indicating the duration.