# US 11,909,472 B2 · Method and apparatus for selection of linear combination coefficients for precoding in frequency-selective channels

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- Number: US 11,909,472 B2
- Document ID: US11909472B2
- Status: Granted
- Kind: B2
- Application number: 17/729,457
- Filed: 2022-04-26
- Published: 2023-05-18
- Granted: 2024-02-20
- Earliest claimed: 2021-11-16
- Assignees: Samsung Electronics Co., Ltd.
- Applicants: Samsung Electronics Co., Ltd.
- Inventors: Federico Penna; Hyukjoon Kwon; Dongwoon Bai; Jaein Kim; Junho Lee; Hui Won Je
- Web page: https://patentgrep.com/patent/US11909472B2

## CPC

- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/048: {using three or more PMIs}
- H04B 7/0632: {Channel quality parameters, e.g. channel quality indicator [CQI]}
- H04L 5/0094: {Indication of how sub-channels of the path are allocated}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

The disclosure provides a method of providing implicit channel state information (CSI) feedback from a user equipment (UE). The method includes determining a precoding matrix indicator (PMI) selection decision metric, selecting one of a sub-band (SB) linear combination coefficient (LCC) selection method, a wideband (WB) LCC selection method, or a sub-band group (SBG) LCC selection method, based on the determined PMI selection decision metric, determining, using the selected LCC selection method, PMI indices based on sub-bands configured by a base station, and transmitting the determined PMI indices to the base station.

## Claims

### Claim 1

A method performed by a user equipment (UE), the method comprising:
determining a precoding matrix indicator (PMI) selection decision metric;
selecting one of a sub-band (SB) linear combination coefficient (LCC) selection method, a wideband (WB) LCC selection method, or a sub-band group (SBG) LCC selection method, based on the determined PMI selection decision metric;
determining, using the selected LCC selection method, PMI indices based on sub-bands configured by a base station; and
transmitting the determined PMI indices to the base station.

### Claim 2 (depends on 1)

The method of claim 1, wherein the determined PMI selection decision metric includes a ratio between LCC energy after frequency domain (FD) compression and LCC energy before FD compression.

### Claim 3 (depends on 2)

The method of claim 2, wherein selecting one of the SB LCC selection method, the WB LCC selection method, or the SBG LCC selection method comprises:
comparing the ratio with a threshold;
selecting the SB LCC selection method, in response to the ratio being greater than the threshold; and
selecting one of the WB LCC selection method or the SBG LCC selection method, in response to the ratio being less than or equal to the threshold.

### Claim 4 (depends on 3)

The method of claim 3, wherein selecting one of the WB LCC selection method or the SBG LCC selection method comprises selecting the SBG LCC selection method, in response to an SB grouping achieving lossless compression.

### Claim 5 (depends on 3)

The method of claim 3, wherein selecting one of the WB LCC selection method or the SBG LCC selection method comprises:
determining a number of the sub-bands configured by the base station and a maximum number of sub-bands; and
selecting one of the WB LCC selection method or the SBG LCC selection method, based on a comparison of the number of the sub-bands configured by the base station and the maximum number of sub-bands, and whether the number of the sub-bands configured by the base station is odd or even.

### Claim 6 (depends on 5)

The method of claim 5, wherein selecting one of the WB LCC selection method or the SBG LCC selection method, based on the comparison of the number of the sub-bands configured by the base station and the maximum number of sub-bands, and whether the number of the sub-bands configured by the base station is odd or even comprises:
selecting the SBG LCC selection method, in response to the number of the sub-bands configured by the base station being less than the maximum number of sub-bands, and the number of the sub-bands configured by the base station being even; and
selecting the WB LCC selection method, in response to the number of the sub-bands configured by the base station being greater than or equal to the maximum number of sub-bands, or the number of the sub-bands configured by the base station being odd.

### Claim 7 (depends on 1)

The method of claim 1, wherein the determined PMI selection decision metric includes an average capacity difference.

### Claim 8 (depends on 7)

The method of claim 7, wherein selecting one of the SB LCC selection method, the WB LCC selection method, or the SBG LCC selection method comprises:
selecting the SB LCC selection method, in response to the average capacity difference being greater than 0; and
selecting one of the WB LCC selection method or the SBG LCC selection method, in response to the average capacity difference being less than or equal to 0.

### Claim 9 (depends on 8)

The method of claim 8, wherein selecting one of the WB LCC selection method or the SBG LCC selection comprises selecting the SBG LCC selection method, in response to an SB grouping achieving lossless compression.

### Claim 10 (depends on 8)

The method of claim 8, wherein selecting one of the WB LCC selection method or the SBG LCC selection method comprises:
determining a number of the sub-bands configured by the base station and a maximum number of sub-bands; and
selecting one of the WB LCC selection method or the SBG LCC selection method, based on a comparison of the number of the sub-bands configured by the base station and the maximum number of sub-bands, and whether the number of the sub-bands configured by the base station is odd or even.

### Claim 11 (depends on 10)

The method of claim 10, wherein selecting one of the WB LCC selection method or the SBG LCC selection method, based on the comparison of the number of the sub-bands configured by the base station and the maximum number of sub-bands, and whether the number of the sub-bands configured by the base station is odd or even comprises:
selecting the SBG LCC selection method, in response to the number of the sub-bands configured by the base station being less than the maximum number of sub-bands, and the number of the sub-bands configured by the base station being even; and
selecting the WB LCC selection method, in response to the number of the sub-bands configured by the base station being greater than or equal to the maximum number of sub-bands, or the number of the sub-bands configured by the base station being odd.

### Claim 12 (depends on 1)

The method of claim 1, wherein the WB LCC selection method comprises:
determining a single LCC matrix for an entire band; and
mapping the single matrix to PMI indices corresponding the SB LCC selection method.

### Claim 13 (depends on 1)

The method of claim 1, wherein the SBG LCC selection method comprises:
determining a set of LCC matrices, wherein a total number of matrices included in the set of the LCC matrices is less than a number of discrete Fourier transform (DFT) components utilized in the SB LCC selection method; and
mapping the set of LCC matrices to PMI indices corresponding the SB LCC selection method.

### Claim 14

A user equipment (UE), comprising:
a transceiver; and
a processor configured to:
determine a precoding matrix indicator (PMI) selection decision metric,
select one of a sub-band (SB) linear combination coefficient (LCC) selection method, a wideband (WB) LCC selection method, or a sub-band group (SBG) LCC selection method, based on the determined PMI selection decision metric,
determine, using the selected LCC selection method, PMI indices based on sub-bands configured by a base station; and
transmit, via the transceiver, the determined PMI indices to the base station.

### Claim 15 (depends on 14)

The UE of claim 14, wherein the determined PMI selection decision metric includes a ratio between LCC energy after frequency domain (FD) compression and LCC energy before FD compression.

### Claim 16 (depends on 15)

The UE of claim 15, wherein the processor is further configured to:
compare the ratio with a threshold,
select the SB LCC selection method, in response to the ratio being greater than the threshold, and
select one of the WB LCC selection method or the SBG LCC selection method, in response to the ratio being less than or equal to the threshold.

### Claim 17 (depends on 16)

The UE of claim 16, wherein the processor is further configured to select the SBG LCC selection method, in response to an SB grouping achieving lossless compression.

### Claim 18 (depends on 16)

The UE of claim 16, wherein the processor is further configured to:
determine a number of the sub-bands configured by the base station and a maximum number of sub-bands, and
select one of the WB LCC selection method or the SBG LCC selection method, based on a comparison of the number of the sub-bands configured by the base station and the maximum number of sub-bands, and whether the number of the sub-bands configured by the base station is odd or even.

### Claim 19 (depends on 18)

The UE of claim 18, wherein the processor is further configured to:
select the SBG LCC selection method, in response to the number of the sub-bands configured by the base station being less than the maximum number of sub-bands, and the number of the sub-bands configured by the base station being even; and
select the WB LCC selection method, in response to the number of the sub-bands configured by the base station being greater than or equal to the maximum number of sub-bands, or the number of the sub-bands configured by the base station being odd.

### Claim 20 (depends on 14)

The UE of claim 14, wherein the determined PMI selection decision metric includes an average capacity difference.

### Claim 21 (depends on 20)

The UE of claim 20, wherein the processor is further configured to:
select the SB LCC selection method, in response to the average capacity difference being greater than 0; and
select one of the WB LCC selection method or the SBG LCC selection method, in response to the average capacity difference being less than or equal to 0.

### Claim 22 (depends on 21)

The UE of claim 21, wherein the processor is further configured to select the SBG LCC selection method, in response to an SB grouping achieving lossless compression.

### Claim 23 (depends on 21)

The UE of claim 21, wherein the processor is further configured to:
determine a number of the sub-bands configured by the base station and a maximum number of sub-bands, and
select one of the WB LCC selection method or the SBG LCC selection method, based on a comparison of the number of the sub-bands configured by the base station and the maximum number of sub-bands, and whether the number of the sub-bands configured by the base station is odd or even.

### Claim 24 (depends on 23)

The UE of claim 23, wherein the processor is further configured to:
select the SBG LCC selection method, in response to the number of the sub-bands configured by the base station being less than the maximum number of sub-bands, and the number of the sub-bands configured by the base station being even; and
select the WB LCC selection method, in response to the number of the sub-bands configured by the base station being greater than or equal to the maximum number of sub-bands, or the number of the sub-bands configured by the base station being odd.

### Claim 25 (depends on 14)

The UE of claim 14, wherein the WB LCC selection method comprises:
determining a single LCC matrix for an entire band; and
mapping the single matrix to PMI indices corresponding the SB LCC selection method.

### Claim 26 (depends on 14)

The UE of claim 14, wherein the SBG LCC selection method comprises:
determining a set of LCC matrices, wherein a total number of matrices included in the set of the LCC matrices is less than a number of discrete Fourier transform (DFT) components utilized in the SB LCC selection method; and
mapping the set of LCC matrices to PMI indices corresponding the SB LCC selection method.