Apparatus

1. An apparatus, comprising:

a processor configured to:

acquire subarray information indicating a plurality of subarrays usable for multilayer Multi-Input Multi-Output (MIMO);

notify a terminal apparatus of the subarray information, wherein the terminal apparatus is a terminal apparatus that performs a report related to a combination of two or more subarrays included in the plurality of subarrays; and

decide a combination of two or more subarrays to be used for the multilayer MIMO for the terminal apparatus on the basis of the report performed by the terminal apparatus, wherein the combination of the two or more subarrays to be used for the multilayer MIMO for the terminal apparatus does not include more than a predetermined number of subarrays that share one or more antenna ports.

2. The apparatus according to claim 1 ,

wherein the subarray information includes information indicating an antenna port included in each of the plurality of subarrays.

3. The apparatus according to claim 1 ,

wherein the subarray information includes identification information identifying each of the plurality of subarrays.

4. The apparatus according to claim 1 ,

wherein the processor is further configured to:

acquire first number information indicating the number of subarrays to be combined for the multilayer MIMO, and

notify the terminal apparatus of the first number information.

5. The apparatus according to claim 1 ,

wherein the processor is further configured to: acquire second number information indicating the number of combinations of subarrays to be reported, and

notify the terminal apparatus of the second number information.

6. The apparatus according to claim 1 ,

wherein the plurality of subarrays includes two or more subarrays that share one or more antenna ports.

7. The apparatus according to claim 1 ,

wherein the processor is further configured to:

acquire combination candidate information indicating one or more combination candidates of two or more subarrays included in the plurality of subarrays, and

notify the terminal apparatus of the combination candidate information.

8. The apparatus according to claim 7 ,

wherein the combination candidate information indicates two or more combination candidates of two or more subarrays included in the plurality of subarrays, and wherein the processor is further configured to:

acquire priority information indicating priorities of the two or more combination candidates, and

notify the terminal apparatus of the priority information.

9. The apparatus according to claim 1 ,

wherein the processor is further configured to:

acquire group information indicating a group of two or more subarrays forming a directional beam in the same radiation direction in the multilayer MIMO among the plurality of subarrays, and

notify the terminal apparatus of the group information.

10. An apparatus, comprising:

a processor configured to:

acquire subarray information indicating a plurality of subarrays usable for multilayer MIMO;

acquire combination candidate information indicating two or more combination candidates of two or more subarrays included in the plurality of subarrays;

perform a report related to a combination of two or more subarrays included in the plurality of subarrays, wherein the report is related to a combination included in the two or more combination candidates;

acquire priority information indicating priorities of the two or more combination candidates; and

perform a report related to a combination included in the two or more combination candidates on the basis of the priority information.

11. The apparatus according to claim 10 ,

wherein the processor is further configured to:

select a combination of two or more subarrays desirable for the multilayer MIMO from among the plurality of subarrays, and

the report includes a report of the combination of the two or more subarrays desirable for the multilayer MIMO.

12. The apparatus according to claim 10 ,

wherein the report includes a report of a weight set for the combination of the two or more subarrays.

13. The apparatus according to claim 12 ,

wherein the weight set includes a weight set for adjusting a phase between the two or more subarrays.

14. The apparatus according to claim 10 ,

wherein the report includes a report of the number of layers for the combination of the two or more subarrays.

15. The apparatus according to claim 10 ,

wherein the report includes a report of a channel quality for the combination of the two or more subarrays.

16. The apparatus according to claim 10 ,

wherein the processor is further configured to:

acquire group information indicating a group of two or more subarrays forming a directional beam in the same radiation direction in the multilayer MIMO among the plurality of subarrays, and

decide a weight set for obtaining directivity for the group on the basis of the group information.