Cross-carrier scheduling with different numerologies

1. A user equipment (UE), comprising:

radio front end circuitry configured to receive a downlink radio frame indicating a plurality of component carriers having more than one subcarrier spacing (SCS); and

processor circuitry, coupled to the radio front end circuitry, configured to:

assign the plurality of component carriers to a number of cell groups, wherein at least one cell group is assigned a first subset of the plurality of component carriers that includes a scheduling component carrier providing scheduling information for other component carriers in the first subset;

select a reference slot window based on an SCS of component carriers assigned to the at least one cell group;

determine, per the reference slot window, a number of physical downlink control channel (PDCCH) candidates that can be monitored by the UE for the at least one cell group, wherein the number of PDCCH candidates is determined based on a number of the component carriers and the SCS of the component carriers in the first subset assigned to the at least one cell group; and

monitor control information in the downlink radio frame based on the number of PDCCH candidates.

2. The UE of claim 1 , wherein the processor circuitry is further configured to:

determine, per the reference slot window, a number of non-overlapped control channel elements (CCEs) that can be monitored by the UE for the at least one cell group, wherein the number of non-overlapped CCEs is determined based on the number of the component carriers and the SCS of the component carriers in the first subset assigned to the at least one cell group; and

monitor control information in the downlink radio frame based on the number of non-overlapped CCEs.

3. The UE of claim 2 , wherein, when the UE is configured with not more than four component carriers, the number of non-overlapped CCEs per the reference slot window for the at least one cell group is a summation of the number of non-overlapped CCEs per the reference slot window for each component carrier in the at least one cell group.

4. The UE of claim 2 , wherein, when the UE is configured with more than four component carriers, the number of non-overlapped CCEs per the reference slot window for the at least one cell group is a minimum of:

a summation of the number of non-overlapped CCEs per the reference slot window for each component carrier in the at least one cell group, and

a product of a number of component carriers the UE is capable of monitoring and a number of non-overlapped CCEs of a reference component carrier, divided by a number of the plurality of component carriers.

5. The UE of claim 4 , wherein the number of non-overlapped CCEs of the reference component carrier is determined based on:

a smallest SCS of component carriers in the at least one cell group,

a largest SCS of component carriers in the at least one cell group,

an SCS of the scheduling component carrier in the at least one cell group, or

a summation of the number of non-overlapped CCEs per the reference slot window for each component carrier in the at least one cell group.

6. The UE of claim 5 , wherein the number of non-overlapped CCEs is further determined based on an offset value and the largest SCS of component carriers in the at least one cell group.

7. The UE of claim 1 , wherein the reference slot window is selected based on a smallest SCS of component carriers in the first subset, a largest SCS of component carriers in the first subset, or an SCS of the scheduling component carrier in the first subset assigned to the at least one cell group.

8. The UE of claim 1 , wherein, when the UE is configured with not more than four component carriers, the number of PDCCH candidates per the reference slot window for the at least one cell group is a summation of the number of PDCCH candidates per the reference slot window for each component carrier in the at least one cell group.

9. The UE of claim 1 , wherein, when the UE is configured with more than four component carriers, the number of PDCCH candidates per the reference slot window for the at least one cell group is a minimum of:

a summation of the number of PDCCH candidates per the reference slot window for each component carrier in the at least one cell group, and

a product of a number of component carriers the UE is capable of monitoring and a number of PDCCH candidates of a reference component carrier, divided by a number of the plurality of component carriers.

10. The UE of claim 9 , wherein the number of PDCCH candidates of the reference component carrier is determined based on:

a smallest SCS of component carriers in the at least one cell group,

a largest SCS of component carriers in the at least one cell group,

an SCS of the scheduling component carrier in the at least one cell group, or

a summation of the number of PDCCH candidates per the reference slot window for each component carrier in the at least one cell group.

11. The UE of claim 10 , wherein the number of PDCCH candidates is further determined based on an offset value and the largest SCS of component carriers in the at least one cell group.

12. A method, comprising:

receiving, by a user equipment (UE), a downlink radio frame indicating a plurality of component carriers having more than one subcarrier spacing (SCS);

assigning the plurality of component carriers to a number of cell groups, wherein at least one cell group is assigned a first subset of the plurality of component carriers that includes a scheduling component carrier providing scheduling information for other component carriers in the first subset;

selecting a reference slot window based on an SCS of component carriers assigned to the at least one cell group;

determining, per the reference slot window, a number of physical downlink control channel (PDCCH) candidates that can be monitored by the UE for the at least one cell group, wherein the number of PDCCH candidates is determined based on a number of the component carriers and the SCS of the component carriers in the first subset assigned to the at least one cell group; and

monitoring control information in the downlink radio frame based on the number of PDCCH candidates.

13. The method of claim 12 , further comprising:

determining, per the reference slot window, a number of non-overlapped control channel elements (CCEs) that can be monitored by the UE for the at least one cell group, wherein the number of non-overlapped CCEs is determined based on the number of the component carriers and the SCS of the component carriers in the first subset assigned to the at least one cell group; and

monitoring control information in the downlink radio frame based on the number of non-overlapped CCEs.

14. The method of claim 12 , wherein the selecting the reference slot window comprises selecting the reference slot window based on a smallest SCS of component carriers in the first subset, a largest SCS of component carriers in the first subset, or an SCS of the scheduling component carrier in the first subset assigned to the at least one cell group.

15. The method of claim 12 , wherein, when the UE is configured with not more than four component carriers, the determining the number of PDCCH candidates comprises summing the number of PDCCH candidates per the reference slot window for each component carrier in the at least one cell group.

16. The method of claim 12 , wherein, when the UE is configured with more than four component carriers, the determining the number of PDCCH candidates comprises calculating a minimum of:

a summation of the number of PDCCH candidates per the reference slot window for each component carrier in the at least one cell group, and

a product of a number of component carriers the UE is capable of monitoring and a number of PDCCH candidates of a reference component carrier, divided by a number of the plurality of component carriers.

17. The method of claim 16 , wherein the number of PDCCH candidates of the reference component carrier is determined based on:

a smallest SCS of component carriers in the at least one cell group,

a largest SCS of component carriers in the at least one cell group,

an SCS of the scheduling component carrier in the at least one cell group, or

a summation of the number of PDCCH candidates per the reference slot window for each component carrier in the at least one cell group.

18. A non-transitory computer-readable medium having instructions stored thereon that, upon execution by at least one processor of a user equipment (UE), cause the UE to perform operations comprising:

receiving a downlink radio frame indicating a plurality of component carriers having more than one subcarrier spacing (SCS);

assigning the plurality of component carriers to a number of cell groups, wherein at least one cell group is assigned a first subset of the plurality of component carriers that includes a scheduling component carrier providing scheduling information for other component carriers in the first subset;

selecting a reference slot window based on an SCS of component carriers assigned to the at least one cell group;

determining, per the reference slot window, a number of physical downlink control channel (PDCCH) candidates that can be monitored by the UE for the at least one cell group, wherein the number of PDCCH candidates is determined based on a number of the component carriers and the SCS of the component carriers in the first subset assigned to the at least one cell group; and

monitoring control information in the downlink radio frame based on the number of PDCCH candidates.

19. The non-transitory computer-readable medium of claim 18 , wherein the operations further comprise:

determining, per the reference slot window, a number of non-overlapped control channel elements (CCEs) that can be monitored by the UE for the at least one cell group, wherein the number of non-overlapped CCEs is determined based on the number of the component carriers and the SCS of the component carriers in the first subset assigned to the at least one cell group; and

monitoring control information in the downlink radio frame based on the number of non-overlapped CCEs.

20. The non-transitory computer-readable medium of claim 18 , wherein the reference slot window is selected based on a smallest SCS of component carriers in the first subset, a largest SCS of component carriers in the first subset, or an SCS of the scheduling component carrier in the first subset assigned to the at least one cell group.