Type-II port-selection codebook generation
Apparatuses, methods, and systems are disclosed for Type-II port-selection codebook generation. One apparatus includes a processor and a transceiver that receives a set of CSI-RS. The processor identifies a set of CSI-RS ports based on the set of CSI-RS. The processor selects a subset of CSI-RS ports from the identified set of CSI-RS ports based on a free selection of the respective CSI-RS ports from the identified CSI-RS ports. The processor generates, based on the set of CSI-RSs, at least one amplitude coefficient indicator and at least one phase coefficient indicator for each selected CSI-RS port generates a CSI report comprising a Type-II port-selection codebook corresponding to the generated coefficients and the subset of CSI-RS ports.
1. A user equipment (“UE”) for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the UE to:
receive a set of Channel State Information (“CSI”) reference signals (“CSI-RSs”);
identify a set of CSI-RS ports based on the set of CSI-RSs;
select a subset of CSI-RS ports from the identified set of CSI-RS ports based on a free selection of the respective CSI-RS ports from the identified CSI-RS ports;
generate, based on the set of CSI-RSs, at least one amplitude coefficient indicator and at least one phase coefficient indicator for each selected CSI-RS port; and
generate a CSI report comprising a Type-II port-selection codebook corresponding to the generated coefficients and the subset of CSI-RS ports.
2. The UE of claim 1 , wherein the CSI report indicates a set of one or more of phase coefficient values for each of the subset of CSI-RS ports.
3. The UE of claim 1 , wherein the set of CSI-RSs corresponds to a plurality of transmission layers, wherein a different subset of the set of CSI-RS ports is selected for each transmission layer.
4. The UE of claim 3 , wherein the CSI report comprises a layer-specific selected subset of the set of CSI-RS ports.
5. The UE of claim 4 , wherein the port selection per layer is polarization-common.
6. The UE of claim 1 , wherein the processor is configured to cause the UE to indicate the free selection of the CSI-RS ports from the identified CSI-RS ports using a bitmap.
7. The UE of claim 1 , wherein the processor is configured to cause the UE to indicate the free selection of the CSI-RS ports from the identified CSI-RS ports using a combinatoric value.
8. The UE of claim 7 , wherein the combinatoric value is in a form of an n-Choose-k mathematical combination function (“C b a ”) that selects an integer-valued “b” elements from a set of integer-valued “a” elements.
9. The UE of claim 8 , wherein a number of bits needed to indicate the free selection of the CSI-RS ports from the identified CSI-RS ports using the combinatoric value is ┌ log 2 C L K/2 ┐ bits, wherein K corresponds to a number of the identified set of CSI-RS ports, L corresponds to a number of beams, log 2 (·) function is a logarithmic function of a base of two, and ┌·┐ is a ceiling function whose output argument is a smallest integer value that is greater than or equal to its input argument.
10. The UE of claim 1 , wherein each indicated amplitude coefficient corresponds to one phase coefficient per CSI-RS port.
11. A base station comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the base station to:
generate a set of Channel State Information (“CSI”) reference signals (“CSI-RSs”);
transmit the set of CSI-RSs to a User Equipment (“UE”);
receive a CSI report from the UE, wherein the CSI report comprises a Type-II port-selection codebook corresponding to a set of generated coefficients and a free selection of CSI-RS ports corresponding to the CSI-RS, at least one amplitude coefficient indicator for each selected CSI-RS port, and at least one phase coefficient indicator for each selected CSI-RS port.
12. The base station of claim 11 , wherein, to transmit the set of CSI-RSs, the processor is configured to cause the base station to beamform the CSI-RSs using a beamforming function, wherein the beamforming function is based on one or more channel characteristics comprising parameters corresponding to one or more angles of arrival and relative delay values for a plurality of different channel paths.
13. The base station of claim 12 , wherein columns of the beamforming function at a given frequency index are based on orthonormal columns drawn from a Fourier-based transform, wherein each of the columns is scaled by a distinct phase value.
14. The base station of claim 12 , wherein columns of the beamforming function at a given frequency index are based on the parameters corresponding to one or more of angles of arrival and relative delay values of a subset of the set of different channel paths.
15. The base station of claim 12 , wherein the one or more channel characteristics are based on a set of uplink reference signals that are received at the base station.
16. A method of performed by a base station, the method comprising:
generating a set of Channel State Information (“CSI”) reference signals (“CSI-RSs”);
transmitting the set of CSI-RSs to a User Equipment (“UE”);
receiving a CSI report from the UE, wherein the CSI report comprises a Type-II port-selection codebook corresponding to a set of generated coefficients and a free selection of CSI-RS ports corresponding to the CSI-RS, at least one amplitude coefficient indicator for each selected CSI-RS port, and at least one phase coefficient indicator for each selected CSI-RS port.
17. The method of claim 16 , wherein transmitting the set of CSI-RSs comprises beamforming the CSI-RSs using a beamforming function, wherein the beamforming function is based on one or more channel characteristics comprising parameters corresponding to one or more angles of arrival and relative delay values for a plurality of different channel paths.
18. The method of claim 17 , wherein columns of the beamforming function at a given frequency index are based on orthonormal columns drawn from a Fourier-based transform, wherein each of the columns is scaled by a distinct phase value.
19. The method of claim 18 , wherein columns of the beamforming function at a given frequency index are based on the parameters corresponding to one or more of angles of arrival and relative delay values of a subset of the set of different channel paths.
20. The method of claim 19 , wherein the one or more channel characteristics are based on a set of uplink reference signals that are received at the base station.