Precoded data receiver
View Patent ↗Methods and apparatus are disclosed for applying successive multi-rank beamforming strategies (e.g., successive precoding strategies) for the design of precoders over a set of parallel channels. Successive beamforming is applied to a narrow band channel model and is also applied for finer quantization of a single beamforming vector (e.g., recursive beamforming). A first embodiment provides the optimal approach with high complexity. An alternative embodiment provides successive beamforming for near optimal precoding selection with medium complexity. A low complexity method for precoder selection is also provided wherein a channel representative matrix for the set of parallel channels is determined and successive beamforming on the calculated channel representative is applied.
1. A method by a mobile terminal for receiving data, comprising:
receiving data transmitted from a remote transmitter and precoded with a precoding matrix selected from a codebook for M transmit antennas, the codebook having entries in the following form
A
(
v
1
,
v
2
,
v
3
,
…
)
=
[
v
1
,
HH
(
v
1
-
e
1
M
)
[
0
v
2
]
,
HH
(
v
1
-
e
1
M
)
[
0
HH
(
v
2
-
e
1
M
-
1
)
[
0
v
3
]
]
]
,
…
where e 1 N =[1, 0, . . . , 0] T εC N , C N being N-dimensional complex space, v a denotes a column vector, HH(v k −e 1 l ) is a rotation matrix that transforms vector v k to the unit vector e 1 l .
2. The method of claim 1 , wherein
HH
(
w
)
=
{
I
-
2
ww
H
w
2
if
w
≠
0
I
if
w
=
0
and is the house-holder transformation.
3. The method of claim 1 , wherein the codebook entries are generated by selecting each vector v a from V a such that
V 1 ={v i 1 εC M } i=1 N 1 ,V 2 ={v i 2 εC M−1 } i=1 N 2 , . . . ,V M−1 ={v i M−1 εC 2 } i=1 N M−1 .
4. The method of claim 1 , wherein the precoding matrix is formed by picking one or more columns from the matrix A(v 1 , v 2 , v 3 , . . . ).
5. The method of claim 4 , wherein the number of selected columns to form the precoding matrix is less than the number of transmit antennas.
6. The method of claim 4 , wherein all the columns are selected to form the precoding matrix.
7. The method of claim 1 , wherein the precoding matrix is generated based on a vector codebook.
8. The method of claim 1 , wherein a transmission rank is determined by the remote transmitter.
9. The method of claim 1 , wherein a transmission rank is determined by the mobile terminal.
10. The method of claim 1 , wherein a scaled version of the precoding matrix is used.
11. The method of claim 1 , wherein the number of transmit antennas is at least 4.
12. The method of claim 1 , wherein the number of transmit antennas is 2.
13. The method of claim 1 , further comprising:
transmitting feedback information to the remote transmitter.
14. The method of claim 13 , wherein the feedback information includes at least one of a rank, a channel quality index (CQI), and a precoding matrix index.
15. The method of claim 13 , wherein the remote transmitter selects the precoding matrix according to the feedback information.
16. A mobile terminal for receiving data, comprising:
a receiving unit to receive data transmitted from a remote transmitter and precoded with a precoding matrix selected from a codebook for M transmit antennas, the codebook having entries in the following form
A
(
v
1
,
v
2
,
v
3
,
…
)
=
[
v
1
,
HH
(
v
1
-
e
1
M
)
[
0
v
2
]
,
HH
(
v
1
-
e
1
M
)
[
0
HH
(
v
2
-
e
1
M
-
1
)
[
0
v
3
]
]
]
,
…
where e 1 N =[1, 0, . . . , 0] T εC N , C N being N-dimensional complex space, v a denotes a column vector, HH(v k −e 1 l ) is a rotation matrix that transforms vector v k to the unit vector e 1 l and v a is selected from a set V a where V 1 ={v i 1 εC M } i=1 N 1 , V 2 ={e 1 M−1 }, V 3 ={e 1 M−2 }, . . . .
17. The mobile terminal of claim 16 , wherein the codebook entries are generated by selecting each vector v a from V a such that
V 1 ={v i 1 εC M } i=1 N 1 ,V 2 ={v i 2 εC M−1 } i=1 N 2 , . . . ,V M−1 ={v i M−1 εC 2 } i=1 N M−1 .
18. A mobile terminal for receiving, comprising:
receiving means for receiving data transmitted from a remote transmitter and precoded with a precoding matrix selected from a codebook for M transmit antennas, the codebook having entries in the following form
A
(
v
1
,
v
2
,
v
3
,
…
)
=
[
v
1
,
HH
(
v
1
-
e
1
M
)
[
0
v
2
]
,
HH
(
v
1
-
e
1
M
)
[
0
HH
(
v
2
-
e
1
M
-
1
)
[
0
v
3
]
]
]
,
…
where e 1 N =[1, 0, . . . , 0] T εC N , C N being N-dimensional complex space, v a denotes a column vector, HH(v k −e 1 l ) is a rotation matrix that transforms vector v k to the unit vector e 1 l and v a is selected from a set V a where V 1 ={v i 1 εC M } i=1 N 1 , V 2 ={e 1 M−1 }, V 3 ={e 1 M−2 }, . . . .
19. The mobile terminal of claim 18 , wherein the codebook entries are generated by selecting each vector v a from V a such that
V 1 ={v i 1 εC M } i=1 N 1 ,V 2 ={v i 2 εC M−1 } i=1 N 2 , . . . ,V M−1 ={v i M−1 εC 2 } i=1 N M−1 .