Channel state information feedback in wireless communication
Methods, systems, and devices for reducing channel state information feedback channel overhead by compressing coefficients of precoding vectors and reporting a subset of the compressed coefficients based on several parameters including network-signaled parameters. Some embodiments may be used in wireless communication embodiments in which channel state information from many layers and many frequency domain units need to be reported.
1. A method for wireless communication, comprising:
determining, by a wireless device, for a layer in R layers, a subset of coefficients from a plurality of coefficients,
wherein R is a rank value and the subset of coefficients comprises less than or equal to K0 non-zero coefficients; and
generating, by the wireless device, a channel state information (CSI) feedback report based on a first plurality of L basis vectors, a second plurality of M basis vectors and the subset of coefficients, wherein the first plurality of L basis vectors, the second plurality of M basis vectors and the subset of coefficients indicate information regarding a precoding vector,
wherein M=ceil(pN3), wherein p and N3 are based on one or more network configured parameters, and wherein L and M are integers; and
transmitting, by the wireless device, the CSI feedback report to a base station.
2. The method of claim 1 , wherein the CSI feedback report comprises an indication of a number of non-zero coefficients across the R layers, and wherein a bit width of the indication of the number of non-zero coefficients across the R layers is based on a maximum number of layers.
3. The method of claim 1 , wherein the CSI feedback report comprises a precoding matrix indicator (PMI) that comprises at least one of an indication of the first plurality of L basis vectors, an indication of the second plurality of M basis vectors, an indication of an amplitude and a phase of the plurality of coefficients, and an indication of locations of non-zero coefficients of the plurality of coefficients.
4. The method of claim 1 , wherein at least one of the L, M, and K0 is constrained such that, when a rank R is larger than a rank R0, a value of K0 for the rank R is equal to a value of K0 for the rank R0, wherein R0 is greater than or equal to one.
5. The method of claim 1 , wherein a maximum number of layers is based on at least one of a network configuration parameter, a capability of the wireless device, and a maximum rank that a codebook used to determine the precoding vector is able to support.
6. A method for wireless communication, comprising:
receiving, by a wireless node, a channel state information (CSI) feedback report from a wireless device,
wherein the CSI feedback report is based on a first plurality of L basis vectors, a second plurality of M basis vectors and a subset of coefficients, wherein the first plurality of L basis vectors, the second plurality of M basis vectors and the subset of coefficients indicate information regarding a precoding vector,
wherein the subset of coefficients is determined from a plurality of coefficients for a layer in R layers, wherein R is a rank value and the subset of coefficients comprises less than or equal to K0 non-zero coefficients,
wherein M=ceil (pN3), wherein p and N3 are based on one or more network configured parameters, and wherein L and M are integers;
performing, by the wireless node, a subsequent communication with the wireless device based on the CSI feedback report.
7. The method of claim 6 , wherein the CSI feedback report comprises an indication of a number of non-zero coefficients across the R layers, and wherein a bit width of the indication of a number of non-zero coefficients across the R layers is based on a maximum number of layers.
8. The method of claim 6 , wherein the CSI feedback report comprises a precoding matrix indicator (PMI) that comprises at least one of an indication of the first plurality of L basis vectors, an indication of the second plurality of M basis vectors, an indication of an amplitude and a phase of the plurality of coefficients, and an indication of locations of non-zero coefficients of the plurality of coefficients.
9. The method of claim 6 , wherein at least one of the L, M, and K0 is constrained such that, when a rank R is larger than a rank R0, a value of K0 for the rank R is equal to a value of K0 for the rank R0, wherein R0 is greater than or equal to one.
10. The method of claim 6 , wherein a maximum number of layers is based on at least one of a network configuration parameter, a capability of the wireless device, and a maximum rank that a codebook used to determine the precoding vector is able to support.
11. A device for wireless communication, comprising at least one processor that is configured to:
determine, for a layer in R layers, a subset of coefficients from a plurality of coefficients,
wherein R is a rank value and the subset of coefficients comprises less than or equal to K0 non-zero coefficients; and
generate a channel state information (CSI) feedback report based on a first plurality of L basis vectors, a second plurality of M basis vectors and the subset of coefficients, wherein the first plurality of L basis vectors, the second plurality of M basis vectors and the subset of coefficients indicate information regarding a precoding vector,
wherein M=ceil(pN3), wherein p and N3 are based on one or more network configured parameters, and wherein L and M are integers; and
transmit the CSI feedback report to a base station.
12. The device of claim 11 , wherein the CSI feedback report comprises an indication of a number of non-zero coefficients across the R layers, and wherein a bit width of the indication of the number of non-zero coefficients across the R layers is based on a maximum number of layers.
13. The device of claim 11 , wherein the CSI feedback report comprises a precoding matrix indicator (PMI) that comprises at least one of an indication of the first plurality of L basis vectors, an indication of the second plurality of M basis vectors, an indication of an amplitude and a phase of the plurality of coefficients, and an indication of locations of non-zero coefficients of the plurality of coefficients.
14. The device of claim 11 , wherein at least one of the L, M, and K0 is constrained such that, when a rank R is larger than a rank R0, a value of K0 for the rank R is equal to a value of K0 for the rank R0, wherein R0 is greater than or equal to one.
15. The device of claim 11 , wherein a maximum number of layers is based on at least one of a network configuration parameter, a capability of the device, and a maximum rank that a codebook used to determine the precoding vector is able to support.
16. A device for wireless communication, comprising at least one processor that is configured to:
receive a channel state information (CSI) feedback report from a wireless device,
wherein the CSI feedback report is based on a first plurality of L basis vectors, a second plurality of M basis vectors and a subset of coefficients, wherein the first plurality of L basis vectors, the second plurality of M basis vectors and the subset of coefficients indicate information regarding a precoding vector,
wherein the subset of coefficients is determined from a plurality of coefficients for a layer in R layers, wherein R is a rank value and the subset of coefficients comprises less than or equal to K0 non-zero coefficients,
wherein M=ceil(pN3), wherein p and N3 are based on one or more network configured parameters, and wherein L and M are integers;
perform a subsequent communication with the wireless device based on the CSI feedback report.
17. The device of claim 16 , wherein the CSI feedback report comprises an indication of a number of non-zero coefficients across the R layers, and wherein a bit width of the indication of a number of non-zero coefficients across the R layers is based on a maximum number of layers.
18. The device of claim 16 , wherein the CSI feedback report comprises a precoding matrix indicator (PMI) that comprises at least one of an indication of the first plurality of L basis vectors, an indication of the second plurality of M basis vectors, an indication of an amplitude and a phase of the plurality of coefficients, and an indication of locations of non-zero coefficients of the plurality of coefficients.
19. The device of claim 16 , wherein at least one of the L, M, and K0 is constrained such that, when a rank R is larger than a rank R0, a value of K0 for the rank R is equal to a value of K0 for the rank R0, wherein R0 is greater than or equal to one.
20. The device of claim 16 , wherein a maximum number of layers is based on at least one of a network configuration parameter, a capability of the wireless device, and a maximum rank that a codebook used to determine the precoding vector is able to support.