# US 10,484,069 B2 · Method for feeding backchannel state information, user equipment, and base station

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- Number: US 10,484,069 B2
- Document ID: US10484069B2
- Status: Granted
- Kind: B2
- Application number: 16/268,284
- Filed: 2019-02-05
- Published: 2019-06-06
- Granted: 2019-11-19
- Earliest claimed: 2012-12-27
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Jianguo Wang; Yongxing Zhou; Leiming Zhang
- Web page: https://patentgrep.com/patent/US10484069B2

## CPC

- H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]}
- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/0634: {Antenna weights or vector/matrix coefficients}
- H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection}
- G06F 17/16: Matrix or vector computation {, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization (matrix transposition G06F7/78)}
- H04B 7/0413: MIMO systems
- H04N 19/124: Quantisation
- H04B: TRANSMISSION
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

Embodiments of the present invention provide a method for feeding back channel state information, a user equipment, and a base station, to improve feedback precision of channel state information. The method includes: receiving a reference signal sent by a base station; selecting a precoding matrix W from a codebook according to the reference signal, where a column vector of the precoding matrix W may be expressed as α[v ejϕv]T, v=[1 ejθ]; and sending a precoding matrix indicator PMI to the base station, where the PMI is corresponding to the selected precoding matrix W. The present invention may further improve quantization precision and achieve balance between overheads and the quantization precision. The base station performs precoding on a sent signal according to a fed back precoding matrix indicator, which can improve precoding precision, thereby improving a data transmission rate and system throughput.

## Claims

### Claim 1

A method performed by a user equipment (UE) for sending channel state information as feedback information to a base station wherein the method comprises:
receiving a reference signal sent by the base station;
selecting a precoding matrix W from a codebook based on an antenna port corresponding to the reference signal, wherein a column vector of the precoding matrix W is expressed as α[v ejϕ]T, v=[1 ejθ], wherein α is a constant, θ and ϕ are phases, and [ ]T indicates transposing of a matrix or vector, wherein the codebook comprises a matrix set; and
sending a precoding matrix indicator (PMI) to the base station, wherein the PMI is corresponding to the selected precoding matrix W,
wherein the matrix set is one of:
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
1
-
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
j
-
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
⁢
⁢
or
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
-
1
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
-
j
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
wherein
θ
=
π
8
⁢
(
4
⁢
i
1
+
2
⁢
⁢
⌊
i
2
/
2
⌋
)
,
i
1
=
0
,
1
,
2
,
3
,
i
2
=
0
,
…
⁢
,
7
,
and
⁢
⁢
⌊
i
2
/
2
⌋
indicates the greatest integer not greater than i2/2.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the precoding matrix W is a precoding matrix obtained after row or column permutation from the matrix set.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the sending a precoding matrix indicator (PMI) to the base station comprises:
sending a first precoding matrix indicator (PMI1) and a second precoding matrix indicator (PMI2) to the base station, wherein PMI1 and PMI2 are respectively used to indicate indexes and i2 corresponding to the selected precoding matrix W.

### Claim 4

A method performed by a base station for receiving channel state information, wherein the method comprises:
sending a reference signal to a user equipment (UE);
receiving a precoding matrix indicator (PMI) sent by the UE, wherein the PMI is corresponding to a precoding matrix W that is selected by the UE from a codebook based on an antenna port corresponding to the reference signal, and a column vector of the precoding matrix W is expressed as α[v ejϕ]T, v=[1 ejθ], wherein a is a constant, θ and ϕ are phases, and [ ]T indicates transposing of a matrix or vector, wherein the codebook comprises a matrix set;
wherein the matrix set is one of:
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
1
-
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
j
-
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
⁢
⁢
or
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
-
1
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
-
j
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
wherein
θ
=
π
8
⁢
(
4
⁢
i
1
+
2
⁢
⁢
⌊
i
2
/
2
⌋
)
,
i
1
=
0
,
1
,
2
,
3
,
i
2
=
0
,
…
⁢
,
7
,
and
⁢
⁢
⌊
i
2
/
2
⌋
indicates the greatest integer not greater than i2/2.

### Claim 5 (depends on 4)

The method according claim 4, wherein the precoding matrix W is a precoding matrix obtained after row or column permutation from the matrix set.

### Claim 6 (depends on 4)

The method according claim 4, wherein the receiving a precoding matrix indicator (PMI) sent by the UE comprises:
receiving a first precoding matrix indicator (PMI1) and a second precoding matrix indicator (PMI2) that are sent by the UE, wherein the PMI1 and the PMI2 are respectively used to indicate indexes i1 and i2 corresponding to the selected precoding matrix.

### Claim 7

A user equipment, comprising:
a receiver, configured to receive a reference signal sent by a base station;
a processor, configured to select a precoding matrix W from a codebook based on an antenna port corresponding to the reference signal received by the receiver, wherein a column vector of the precoding matrix W is expressed as α[v ejϕ]T, v=[1 ejθ], wherein α is a constant, θ and ϕ are phases, and [ ]T indicates transposing of a matrix or vector, wherein the codebook comprises a matrix set; and
a transmitter, configured to send a precoding matrix indicator (PMI) to the base station, wherein the PMI is corresponding to the precoding matrix W selected by the processor;
wherein the matrix set is one of:
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
1
-
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
j
-
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
⁢
⁢
or
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
-
1
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
-
j
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
wherein
θ
=
π
8
⁢
(
4
⁢
i
1
+
2
⁢
⁢
⌊
i
2
/
2
⌋
)
,
i
1
=
0
,
1
,
2
,
3
,
i
2
=
0
,
…
⁢
,
7
,
and
⁢
⁢
⌊
i
2
/
2
⌋
indicates the greatest integer not greater than i2/2.

### Claim 8 (depends on 7)

The user equipment according to claim 7, wherein the precoding matrix W is a precoding matrix obtained after row or column permutation from the matrix set.

### Claim 9 (depends on 7)

The user equipment according to claim 7, wherein the transmitter is specifically configured to:
send a first precoding matrix indicator (PMI1) and a second precoding matrix indicator (PMI2) to the base station, wherein the PMI1 and the PMI2 are respectively used to indicate indexes i1 and i2 corresponding to the selected precoding matrix.

### Claim 10

Abase station, comprising:
a transmitter, configured to send a reference signal to a user equipment (UE);
a receiver, configured to receive a precoding matrix indicator (PMI) sent by the UE, wherein the PMI is corresponding to a precoding matrix W that is selected by the UE from a codebook based on an antenna port corresponding to the reference signal, and a column vector of the precoding matrix W is expressed as α[v ejϕ]T, v=[1 ejθ], wherein α is a constant, θ and ϕ are phases, and [ ]T indicates transposing of a matrix or vector, wherein the codebook comprises a matrix set;
wherein the matrix set is one of:
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
1
-
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
j
-
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
⁢
⁢
or
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
-
1
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
-
j
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
wherein
θ
=
π
8
⁢
(
4
⁢
i
1
+
2
⁢
⁢
⌊
i
2
/
2
⌋
)
,
i
1
=
0
,
1
,
2
,
3
,
i
2
=
0
,
…
⁢
,
7
,
and
⁢
⁢
⌊
i
2
/
2
⌋
indicates the greatest integer not greater than i2/2.

### Claim 11 (depends on 10)

The base station according to claim 10, wherein the precoding matrix W is a precoding matrix obtained after row or column permutation from the matrix set.

### Claim 12 (depends on 10)

The base station according to claim 10, wherein the receiver is specifically configured to:
receive a first precoding matrix indicator (PMI1) and a second precoding matrix indicator (PMI2) that are sent by the user equipment to the base station, wherein the PMI1 and the PMI2 are respectively used to indicate indexes i1 and i2 corresponding to the selected precoding matrix.

### Claim 13

An apparatus, comprising:
a processor; and
a non-transitory computer-readable storage medium storing a program to be executed by the processor, the program including instructions for:
receiving a reference signal sent by a base station;
selecting a precoding matrix W from a codebook based on an antenna port corresponding to the reference signal wherein a column vector of the precoding matrix W is expressed as α[v ejϕ]T, v=[1 ejθ], wherein α is a constant, θ and ϕ are phases, and [ ]T indicates transposing of a matrix or vector, wherein the codebook comprises a matrix set; and
sending a precoding matrix indicator (PMI) to the base station, wherein the PMI is corresponding to the selected precoding matrix W,
wherein the matrix set is one of:
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
1
-
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
j
-
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
⁢
⁢
or
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
-
1
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
-
j
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
wherein
θ
=
π
8
⁢
(
4
⁢
i
1
+
2
⁢
⁢
⌊
i
2
/
2
⌋
)
,
i
1
=
0
,
1
,
2
,
3
,
i
2
=
0
,
…
⁢
,
7
,
and
⁢
⁢
⌊
i
2
/
2
⌋
indicates the greatest integer not greater than i2/2.

### Claim 14 (depends on 13)

The apparatus according to claim 13, wherein the precoding matrix W is a precoding matrix obtained after row or column permutation from the matrix set.

### Claim 15 (depends on 13)

The apparatus according to claim 13, wherein the sending a precoding matrix indicator (PMI) to the base station comprises:
sending a first precoding matrix indicator (PMI1) and a second precoding matrix indicator (PMI2) to the base station, wherein PMI1 and PMI2 are respectively used to indicate indexes i1 and i2 corresponding to the selected precoding matrix W.

### Claim 16

An apparatus, comprising:
a processor; and
a non-transitory computer-readable storage medium storing a program to be executed by the processor, the program including instructions for:
sending a reference signal to a user equipment (UE);
receiving a precoding matrix indicator (PMI) sent by the UE, wherein the PMI is corresponding to a precoding matrix W that is selected by the UE from a codebook based on an antenna port corresponding to the reference signal, and a column vector of the precoding matrix W is expressed as α[v ejϕ]T, v=[1 ejθ], wherein α is a constant, θ and ϕ are phases, and [ ]T indicates transposing of a matrix or vector, wherein the codebook comprises a matrix set;
wherein the matrix set is one of:
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
1
-
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
j
-
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
⁢
⁢
or
{
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
1
-
1
1
-
1
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
]
,
1
4
⁡
[
1
1
1
1
e
j
⁢
⁢
θ
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
-
e
j
⁢
⁢
θ
j
-
j
j
-
j
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
-
je
j
⁢
⁢
θ
je
j
⁢
⁢
θ
]
}
wherein
θ
=
π
8
⁢
(
4
⁢
i
1
+
2
⁢
⁢
⌊
i
2
/
2
⌋
)
,
i
1
=
0
,
1
,
2
,
3
,
i
2
=
0
,
…
⁢
,
7
,
and
⁢
⁢
⌊
i
2
/
2
⌋
indicates the greatest integer not greater than i2/2.

### Claim 17 (depends on 16)

The apparatus according to claim 16, wherein the precoding matrix W is a precoding matrix obtained after row or column permutation from the matrix set.

### Claim 18 (depends on 16)

The apparatus according to claim 16, wherein the receiving a precoding matrix indicator (PMI) sent by the UE comprises:
receiving a first precoding matrix indicator (PMI1) and a second precoding matrix indicator (PMI2) that are sent by the UE, wherein the PMI1 and the PMI2 are respectively used to indicate indexes i1 and i2 corresponding to the selected precoding matrix.