Communication system using a multi-antenna transmit precoder codebook
View Patent ↗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.
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 another communication device;
wherein the processor is further configured to select an index for the first precoder component, wherein the transmitter is configured to signal the index to the another 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.
2. 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 another communication device.
3. The communication device of claim 1 , wherein the processor is further configured to determine an antenna configuration of the another communication device and to determine the 4Tx precoder from a sub-codebook of the codebook associated with the determined antenna configuration.
4. The communication device of claim 3 , wherein the antenna configuration of the another 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 another communication device.
5. The communication device of claim 3 , wherein the antenna configuration of the another 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 another communication device.
6. The communication device of claim 3 , wherein the antenna configuration of the another 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
ⅇ
-
jθ
2
i
ⅇ
-
jθ
2
i
+
1
]
,
θ
i
=
2
π
i
8
,
and N is an integer.
7. 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.
8. The communication device of claim 5 , wherein the second precoder component is configured to compensate for a cross-polarization phase difference between antennas of the another communication device.
9. The communication device of claim 8 , wherein the second precoder component is further configured to compensate for a short term or a narrowband variation of the separation phase difference.
10. 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 another communication device;
wherein the processor is further configured to determine an antenna configuration of the another communication device and to determine the 4Tx precoder from a sub-codebook of the codebook associated with the determined antenna configuration; and
wherein the antenna configuration of the another 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:
W 1 (i )=[v ULA (θ 2i−2)v ULA (θ 2i)v ULA (θ 2i+1)], i= 0 , . . . , N
wherein
θ
k
=
2
π
k
16
and N is an integer, and wherein v ULA (θ) is given by:
v
ULA
(
θ
)
=
[
1
ⅇ
-
jθ
ⅇ
-
j2θ
ⅇ
-
j3
θ
]
.
11. The communication device of claim 10 , 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.
12. The communication device of claim 10 , wherein the processor is further configured to select an index for the first precoder component, wherein the transmitter is configured to signal the index to the another 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.
13. The communication device of claim 10 , 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 another communication device.
14. 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 another communication device;
wherein the processor is further configured to determine an antenna configuration of the another communication device and to determine the 4Tx precoder from a sub-codebook of the codebook associated with the determined antenna configuration; and
wherein the antenna configuration of the another 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
ⅇ
-
jθ
1
c
c
ⅇ
-
jθ
2
]
.
15. The communication device of claim 14 , 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.
16. The communication device of claim 14 , wherein the processor is further configured to select an index for the first precoder component, wherein the transmitter is configured to signal the index to the another 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.
17. 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;
wherein the processor is further configured to select an index for the first precoder component, wherein the transmitter is configured to signal the index to the second 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.
18. The system of claim 17 , wherein the first communication device includes a user equipment (UE) and the second communication device includes a base station.
19. The system of claim 17 , 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.
20. The system of claim 19 , wherein the second precoder component is configured to compensate for a short term or a narrowband variation of the separation phase difference.