# US 2014/0192916 A1 · Communication System Using a Multi-Antenna Transmit Precoder Codebook

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- Number: US 2014/0192916 A1
- Document ID: US20140192916A1
- Status: Published application
- Kind: A1
- Application number: 14/147,245
- Filed: 2014-01-03
- Published: 2014-07-10
- Earliest claimed: 2013-01-10
- Assignees: Broadcom Corporation
- Applicants: Broadcom Corporation
- Inventors: Krishna Srikanth GOMADAM; Djordje Tujkovic
- Web page: https://patentgrep.com/patent/US20140192916A1

## CPC

- H04B 7/0469: {taking special antenna structures, e.g. cross polarized antennas into account}
- H04B 7/0481: {using subset selection of codebooks}
- H04B 7/065: {Variable contents, e.g. long-term or short-short}
- H04B: TRANSMISSION

## Abstract

Systems using a transmit precoder codebook designed for a four-transmitter (4Tx) antenna configuration are described. The 4Tx antenna configuration is an attractive option for base stations in cellular network environments due to site-acquiring advantages and robust performance. In an embodiment, the transmit precoder codebook can be used for a variety of transmit antenna configurations and has a high resolution to enable beamforming and/or nulling. In another embodiment, the transmit precoder codebook is a two-component codebook, with a first precoder component signaled at a first frequency and a second precoder component signaled at a second higher frequency.

## Claims

### Claim 1

A communication device, comprising:
a channel estimation module configured to generate a channel estimate of a channel from another communication device;
a processor configured to determine a four-transmitter (4Tx) precoder from a codebook based on the channel estimate, wherein the 4Tx precoder includes a first precoder component and a second precoder component; and
a transmitter configured to signal the first precoder component and the second precoder component to the other communication device.

### Claim 2 (depends on 1)

The communication device of claim 1, wherein the transmitter is configured to signal the first precoder component at a lower frequency than the second precoder component to the other communication device.

### Claim 3 (depends on 1)

The communication device of claim 1, wherein the processor is further configured to determine an antenna configuration of the other communication device and to determine the 4Tx precoder from a sub-codebook of the codebook associated with the determined antenna configuration.

### Claim 4 (depends on 3)

The communication device of claim 3, wherein the antenna configuration of the other communication device corresponds to a Uniform Linear Array configuration, and wherein the first precoder component is configured to compensate for a long term or a wideband variation of a separation phase difference between antennas of the other communication device.

### Claim 5 (depends on 4)

The communication device of claim 4, wherein the second precoder component is configured to compensate for a short term or a narrowband variation of the separation phase difference.

### Claim 6 (depends on 3)

The communication device of claim 3, wherein the antenna configuration of the other communication device corresponds to a Uniform Linear Array configuration, and wherein the processor is further configured to select the first precoder component as a vector from a plurality of vectors of a precoder matrix, wherein the precoder matrix is given by:
W1(i)=[vULA(θ2i−1) vULA(θ2i−1) vULA(θ2i) vULA(θ2i+1)], i=0, . . . , N
wherein
θ
k
=
2

π


k
16
and N is an integer, and wherein vULA(θ) is given by:
v
ULA

(
θ
)
=
[
1

-
jθ

-
j2θ

-
j3


θ
]
.

### Claim 7 (depends on 6)

The communication device of claim 6, wherein the vector of the precoder matrix includes a plurality of elements, wherein the second precoder component is configured to select an element of the plurality of elements of the vector as the 4Tx precoder.

### Claim 8 (depends on 3)

The communication device of claim 3, wherein the antenna configuration of the other communication device corresponds to a Closely Spaced Cross Polarized Antenna Array configuration, and wherein the first precoder component is configured to compensate for a long term or a wideband variation of a separation phase difference between antennas of the other communication device.

### Claim 9 (depends on 8)

The communication device of claim 8, wherein the second precoder component is configured to compensate for a cross-polarization phase difference between antennas of the other communication device.

### Claim 10 (depends on 9)

The communication device of claim 9, wherein the second precoder component is further configured to compensate for a short term or a narrowband variation of the separation phase difference.

### Claim 11 (depends on 3)

The communication device of claim 3, wherein the antenna configuration of the other communication device corresponds to a Closely Spaced Cross Polarized Antenna Array configuration, and wherein the processor is further configured to select the first precoder component as a matrix from a plurality of matrices given by:
W
1

(
i
)
=
[
X

(
i
)
0
0
C

(
i
)
]
,
i
=
0
,
…

,
N
wherein
X

(
i
)
=
[
1
1

-
jθ
2

i

-
jθ
2

i
+
1
]
,

θ
i
=
2

π


i
8
,
and N is an integer.

### Claim 12 (depends on 3)

The communication device of claim 3, wherein the antenna configuration of the other communication device corresponds to a Widely Spaced Cross Polarized Antenna Array configuration, and wherein the processor is further configured to select the first precoder component as a matrix from a plurality of matrices given by:
W
1

(
1
)
=
[
v
UNCOR

(
θ
1
,
θ
2
,
c
=
1
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
1
)
]
θ
1
=
0
,
θ
2
=
0
W
1

(
2
)
=
[
v
UNCOR

(
θ
1
,
θ
2
,
c
=
1
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
1
)
]
θ
1
=
0
,
θ
2
=
π
W
1

(
3
)
=
[
v
UNCOR

(
θ
1
,
θ
2
,
c
=
1
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
1
)
]
θ
1
=
π
,
θ
2
=
0
W
1

(
4
)
=
[
v
UNCOR

(
θ
1
,
θ
2
,
c
=
1
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
j
)
v
UNCOR

(
θ
1
,
θ
2
,
c
=
-
1
)
]
θ
1
=
π
,
θ
2
=
π
wherein
v
UNCORR

(
θ
1
,
θ
2
,
c
)
=
[
1

-
jθ
1
c
c



-
jθ
2
]
.

### Claim 13 (depends on 12)

The communication device of claim 12, wherein the matrix includes a plurality of column vectors, and wherein the second precoder component is configured to select one of the plurality of column vectors of the matrix as the 4Tx precoder.

### Claim 14 (depends on 1)

The communication device of claim 1, wherein the processor is further configured to select an index for the first transmit precoder component, wherein the transmitter is configured to signal the index to the other communication device, wherein the index indicates a plurality of 4Tx precoders from a finite set of consecutive uniformly spaced 4Tx precoders, and wherein the plurality of 4TX precoders are non-consecutive within the finite set of consecutive uniformly spaced 4TX precoders.

### Claim 15

A system, comprising:
a first communication device; and
a second communication device,
wherein the first communication device comprises:
a channel estimation module configured to generate a channel estimate of a channel from the second communication device;
a processor configured to determine a four-transmitter (4Tx) precoder from a codebook based on the channel estimate, wherein the 4Tx precoder includes a first precoder component and a second precoder component; and
a transmitter configured to signal the first precoder component and the second precoder component to the second communication device.

### Claim 16 (depends on 15)

The system of claim 15, wherein the first communication device includes a user equipment (UE) and the second communication device includes a base station.

### Claim 17 (depends on 15)

The system of claim 15, wherein the first precoder component is configured to compensate for a long term or a wideband variation of a separation phase difference between antennas of the second communication device.

### Claim 18 (depends on 17)

The system of claim 17, wherein the second precoder component is configured to compensate for a short term or a narrowband variation of the separation phase difference.

### Claim 19

A communication device, comprising:
a channel estimation module configured to generate a channel estimate of a channel from another communication device; and
a processor configured to determine an antenna configuration of the other communication device and to determine a four-transmitter (4Tx) precoder from a codebook based on the channel estimate and the determined antenna configuration, wherein the 4Tx precoder includes a first precoder component and a second precoder component.

### Claim 20 (depends on 19)

The communication device of claim 19, further comprising:
a transmitter configured to signal the first precoder component and the second precoder component to the other communication device.

### Claim 21 (depends on 19)

The communication device of claim 19, wherein the first precoder component is configured to compensate for a long term or a wideband variation of the channel and the second precoder component is configured to compensate for a short term or a narrowband variation of the channel.