4TX codebook enhancement in LTE
Channel state information (CSI) feedback in a wireless communication system is disclosed. A precoding matrix is generated for multi-antenna transmission based on precoding matrix indicator (PMI) feedback, wherein the PMI indicates a choice of precoding matrix derived from a matrix multiplication of two matrices from a first codebook and a second codebook. In one embodiment, the first codebook comprises at least a first precoding matrix constructed with a first group of adjacent Discrete-Fourier-Transform (DFT) vectors. In another embodiment, the first codebook comprises at least a second precoding matrix constructed with a second group of uniformly distributed non-adjacent DFT vectors. In yet another embodiment, the first codebook comprises at least a first precoding matrix and a second precoding matrix, where said first precoding matrix is constructed with a first group of adjacent DFT vectors, and said second precoding matrix is constructed with a second group of uniformly distributed non-adjacent DFT vectors.
1. A method of channel state information (CSI) feedback in a wireless communication system, comprising:
receiving one or more precoding matrix indicator (PMI) signals from a remote transceiver; and
generating a precoding matrix W derived from a matrix multiplication of two matrices W 1 and W 2 , where said precoding matrix W is applicable to precoding one or more layers of data streams, matrix W 1 selected from a first codebook C 1 based on a first group of bits in the PMI signals, arid matrix W 2 selected from a second codebook C 2 based on a second group of bits in the PMI signals, wherein the first codebook C 1 comprises the following W 1 matrices constructed by non-adjacent Discrete Fourier Transform (DFT) vectors:
B
=
[
b
0
b
1
…
b
N
-
1
]
,
[
B
]
1
+
m
,
1
+
n
=
ⅇ
j
2
π
mn
N
,
m
=
0
,
…
N
t
2
-
1
,
n
=
0
,
1
,
…
,
N
-
1
,
X
(
k
)
∈
{
⌊
b
k
mod
N
b
(
k
+
N
/
4
)
mod
N
b
(
k
+
2
×
N
/
4
)
mod
32
b
(
k
+
3
×
N
/
4
)
mod
32
⌋
:
k
=
0
,
1
,
…
,
N
4
-
1
}
,
W
1
(
k
)
=
[
X
(
k
)
0
0
X
(
k
)
]
,
C
1
=
{
W
1
(
0
)
,
W
1
(
1
)
,
W
1
(
2
)
,
…
,
W
1
(
N
/
4
-
1
)
}
,
N t ≧4 is the number of transmit antennas corresponding to W,
N is the maximum number of layers, an integer number greater than or equal to N t ,
m is the beam index,
n is the layer index,
k is the codebook index and
X (k) is the block diagonal sub-matrix of W (k) .
2. The method of claim 1 , wherein the number of layers of the data stream is one, and wherein the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
Y
]
,
1
2
[
Y
j
Y
]
,
1
2
[
Y
-
Y
]
,
1
2
[
Y
-
j
Y
]
}
,
Y
∈
{
e
~
1
,
e
~
2
,
e
~
3
,
e
~
4
}
,
and
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y is the sub-matrix of codebook C 2 .
3. The method of claim 1 , wherein the number of layers of the data stream is two, and wherein the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
1
)
,
(
e
~
2
,
e
~
2
)
,
(
e
~
3
,
e
~
3
)
,
(
e
~
4
,
e
~
4
)
,
(
e
~
1
,
e
~
2
)
,
(
e
~
2
,
e
~
3
)
,
(
e
~
1
,
e
~
4
)
,
(
e
~
2
,
e
~
4
)
}
,
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y 1 , Y 2 are sub-matrices of codebook C 2 .
4. The method of claim 1 , wherein the number of layers of the data stream is two, and wherein the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
-
Y
2
]
}
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
3
)
,
(
e
~
2
,
e
~
4
)
}
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1and Y 1 , Y 2 are sub-matrices of codebook C 2 .
5. The method of claim 1 , wherein the number of layers of the data stream is two, and wherein the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
j
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
,
1
2
[
Y
1
Y
2
-
j
Y
1
j
Y
2
]
,
1
2
[
Y
1
Y
2
-
j
Y
1
-
j
Y
2
]
}
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
3
)
}
or
{
(
e
~
2
,
e
~
4
)
}
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y 1 , Y 2 are sub-matrices of codebook C 2 .
6. The method of claim 1 , wherein N=32.
7. A method of channel state information (CSI) feedback in a wireless communication system, comprising:
receiving one or more precoding matrix indictor (PMI) signals from a remote transceiver; and
generating a precoding matrix W derived from a matrix multiplication of two matrices W 1 and W 2 , where said precoding matrix W is applicable to precoding one or more layers of data streams, matrix W 1 selected from a first codebook C 1 based on a first group of bits in the PMI signals, and matrix W 2 selected from a second codebook C 2 based on a second group of bits in the PMI signals, wherein the first codebook C 1 comprises at least a first W 1 matrix and a second W 1 matrix, wherein said at least first W 1 matrix is constructed with a first group of adjacent Discrete Fourier Transform (DFT) vectors, and
B
=
[
b
0
b
1
…
b
31
]
,
[
B
]
1
+
m
,
1
+
n
=
ⅇ
j
2
π
mn
32
,
m
=
0
,
…
N
t
2
-
1
,
n
=
0
,
1
,
…
,
31
,
for
i
1
=
0
,
1
,
…
,
7
:
X
(
i
1
)
∈
{
[
b
2
i
1
mod
16
b
(
2
i
1
+
1
)
mod
16
b
(
2
i
1
+
2
)
mod
16
b
(
2
i
1
+
3
)
mod
16
]
}
,
b
n
(
m
+
1
)
=
ⅇ
j
2
π
mn
16
,
n
=
0
,
1
,
…
,
15
,
m
=
0
,
…
1
for
i
1
=
8
,
9
,
…
,
15
:
X
(
i
1
)
∈
{
[
b
(
i
1
-
8
)
mod
32
b
(
i
1
-
8
)
+
8
mod
32
b
(
i
1
-
8
)
+
16
mod
32
b
(
i
1
-
8
)
+
24
mod
32
]
}
b
n
(
m
+
1
)
=
ⅇ
j
2
π
mn
32
,
n
=
0
,
1
,
…
,
31
,
m
=
0
,
…
1
W
1
(
i
1
)
=
[
X
(
i
1
)
0
0
X
(
i
1
)
]
,
C
1
=
{
W
1
(
0
)
,
W
1
(
1
)
,
W
1
(
2
)
,
…
,
W
1
(
15
)
}
,
said at least second W 1 matrix is constructed with a second group of non-adjacent DFT vectors, and
N t ≧4 is the number of transmit antennas corresponding to W,
m is the beam index,
n is the layer index,
X (k) is the block diagonal sub-matrix of W (k) .
8. The method of claim 7 , further comprising:
precoding one or more layers of a data stream at a base station by multiplication with the precoding matrix W; and
transmitting the precoded layers in the data stream to the remote transceiver.
9. The method of claim 7 , wherein the number of layers of the data stream is one, and wherein the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
Y
]
,
1
2
[
Y
j
Y
]
,
1
2
[
Y
-
Y
]
,
1
2
[
Y
-
j
Y
]
}
,
Y
∈
{
e
~
1
,
e
~
2
,
e
~
3
,
e
~
4
}
,
and
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y is a sub-matrix of codebook C 2 .
10. The method of claim 7 , wherein the number of layers of the data stream is two, and wherein i i =0,1, . . ., 7, the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
1
)
,
(
e
~
2
,
e
~
2
)
,
(
e
~
3
,
e
~
3
)
,
(
e
~
4
,
e
~
4
)
,
(
e
~
1
,
e
~
2
)
,
(
e
~
2
,
e
~
3
)
,
(
e
~
1
,
e
~
4
)
,
(
e
~
2
,
e
~
4
)
}
,
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y1, Y2 are sub-matrices of codebook C 2 .
11. The method of claim 7 , wherein the number of layers of the data stream is two, and wherein i 1 =0,1, . . .,7, the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
1
)
(
e
~
2
,
e
~
2
)
,
(
e
~
3
,
e
~
3
)
,
(
e
~
4
,
e
~
4
)
}
,
wherein {tilde over (e)} 1 is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y1, Y2 are sub-matrices of codebook C 2 .
12. The method of claim 7 , wherein the number of layers of the data stream is two, and wherein i 1 =8, 9, . . ., 15, the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
j
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
1
2
[
Y
1
Y
2
-
j
Y
1
j
Y
2
]
,
1
2
[
Y
1
Y
2
-
j
Y
1
-
j
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
3
)
,
(
e
~
2
,
e
~
4
)
}
,
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y1, Y2 are sub-matrices of codebook C 2 .
13. The method of claim 7 , wherein the number of layers of the data stream is two, and wherein i 1 =8, 9, . . ., 15, the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
-
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
3
)
,
(
e
~
2
,
e
~
4
)
}
,
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y1, Y2 are sub-matrices of codebook C 2 .
14. The method of claim 7 , wherein the number of layers of the ata stream is two, and wherein i 1 =8,9, . . .,15 , the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
Y
2
]
,
1
2
[
Y
1
Y
2
-
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
j
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
1
2
[
Y
1
Y
2
-
j
Y
1
j
Y
2
]
,
1
2
[
Y
1
Y
2
-
j
Y
1
-
j
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
3
)
}
or
{
(
e
~
2
,
e
~
4
)
}
,
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y1, Y2 are sub-matrices of codebook C 2 .
15. A method of channel state information (CSI) feedback in a wireless communication system, comprising;
receiving one or more precoding matrix indicator (PMI) signals from a remote transceiver; and
generating a precoding matrix W derived from a matrix multiplication of two matrices W 1 and W 2 , where said precoding matrix W is applicable to precoding one or more layers of data streams, matrix W 1 selected from a first codebook C 1 based on a first group of bits in the PMI signals, and matrix W 2 selected from a second codebook C 2 based on a second group of bits in the PMI signals, wherein the first codebook C 1 comprises at least the following matrix constructed by a set of adjacent Discrete Fourier Transform (DFT) vectors:
B
=
[
b
0
b
1
…
b
31
]
,
[
B
]
1
+
m
,
1
+
n
=
ⅇ
j
2
π
mn
32
,
m
=
0
,
…
N
t
2
-
1
,
n
=
0
,
1
,
…
,
31
,
X
(
k
)
∈
{
[
b
2
k
mod
32
b
(
2
k
+
1
)
mod
32
b
(
2
k
+
2
)
mod
32
b
(
2
k
+
3
)
mod
32
]
:
k
=
0
,
1
,
…
,
15
}
,
W
1
(
k
)
=
[
X
(
k
)
0
0
X
(
k
)
]
,
C
1
=
{
W
1
(
0
)
,
W
1
(
1
)
,
W
1
(
2
)
,
…
,
W
1
(
15
)
}
,
N t =4 is the number of transmit antennas corresponding W,
m is the beam index,
n is the layer index,
X (k) is the block diagonal sub-matrix of W (k) , wherein the number of layers of the data stream is two, and wherein the second codebook C 2 comprises at least the following matrix:
W
2
∈
C
2
=
{
1
2
[
Y
1
Y
2
Y
1
-
Y
2
]
,
1
2
[
Y
1
Y
2
j
Y
1
-
j
Y
2
]
}
,
(
Y
1
,
Y
2
)
∈
{
(
e
~
1
,
e
~
1
)
,
(
e
~
2
,
e
~
2
)
,
(
e
~
3
,
e
~
3
)
,
(
e
~
4
,
e
~
4
)
}
,
wherein {tilde over (e)} i is a 4×1 vector with all zero entries except for the i-th element which has value 1 and Y1, Y2 are sub-matrices of codebook C 2 .