Method of generating codebook of uniform circular array and acquiring codeword from the codebook
View Patent ↗The present invention proposes a technical solution of codebook design which is suitable for antennas configured in a uniform circular array. Respective codewords in the designed codebooks have constant modulus, respective columns being orthogonal to each other and nested property. Based on the designed codebook, the invention further provides a method of determining a codeword in a base station of a MIMO communication system, the base station being configured with N t antennas in a uniform circular array, wherein the method comprises the steps of receiving codeword index information from a user equipment; and determining a target codeword corresponding to the codeword index information from a set of codebooks according to the codeword index information,wherein the set of codebooks comprises N t codebooks corresponding respectively to respective ranks and the N t codebooks are determined based upon a codebook of rank 1 and a N t ×N t Hadamard matrix, the first column of the Hadamard matrix is all 1 or all −1. As compared with the existing Rel-10 codebook, the codebooks designed according to the invention can reduce a feedback overhead and improve the average spectrum efficiency of a cell and spectrum efficiency of a user at the edge of the cell.
1. A method of generating a set of codebooks, the set of codebooks being suitable for a MIMO communication system in which a base station is configured with N t transmission antennas and the N t transmission antennas are configured in a uniform circular array, the set of codebooks comprising N t codebooks corresponding respectively to respective ranks, wherein the method comprises:
determining the N t codebooks in the set of codebooks based upon a N t ×N t Hadamard matrix D and a codebook C 1 of rank 1,
wherein the first column of the Hadamard matrix D is all 1 or all −1, and the codebook of rank 1 is
C
1
=
{
W
1
(
mN
+
n
)
,
m
=
0
,
1
,
…
,
M
-
1
;
n
=
0
,
1
,
…
,
N
-
1
}
,
wherein
W
1
(
mN
+
n
)
=
diag
(
D
(
:
,
1
)
)
·
v
m
,
n
,
V
m
,
n
=
1
N
t
[
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
1
)
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
2
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
i
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
N
t
)
]
T
,
D(:,1) represents the first column of the Hadamard matrix D, diag(D(:,1)) represents a diagonal matrix with main diagonal elements being the first column of the Hadamard matrix D, R represents the radius of the uniform circular array, θ i represents an azimuth angle of the i th antenna, and λ represents the wavelength of the electromagnetic wave emitted from the base station.
2. The method according to claim 1 , wherein a codebook C r of rank r among the N t codebooks is determined in the formula of:
C r ={W r (mN+n) , m= 0,1, . . . , M− 1; n= 0,1, . . . , N− 1},
wherein W r (mN+n) =X m,n (:,1:r)/√r, 1≦r≦N t , X m,n represents a N t ×N t matrix, X m,n (:,1:r) represents a matrix composed of the first to r th column vectors of the matrix X m,n , and X m,n is constructed by the equation of:
X m,n (:, k )=diag( D (:, k ))* v m,n , k= 1,2, . . . , N t ,
wherein D represents the N t ×N t Hadamard matrix with the first column which is all 1 or all −1, X m,n (:,k) represents the k th column vector of the matrix X m,n , D(:,k) represents the k th column vector of the matrix D, and diag(D(:,k)) represents a diagonal matrix with main diagonal elements being the k th column vector of the matrix D.
3. A method of determining a codeword in a base station of a MIMO communication system, the base station being configured with N t antennas in a uniform circular array, wherein the method comprises:
receiving codeword index information from a user equipment; and
determining a target codeword corresponding to the codeword index information from a set of codebooks according to the codeword index information, determining a target codeword corresponding to the codeword index information from a set of codebooks according to the codeword index information,
wherein the set of codebooks comprises N t codebooks corresponding respectively to respective ranks and the N t codebooks are determined based on a N t ×N t Hadamard matrix D and a codebook C 1 of rank 1,
wherein the first column of the Hadamard matrix D is all 1 or all −1, and the codebook of rank 1 is
C
1
=
{
W
1
(
mN
+
n
)
,
m
=
0
,
1
,
…
,
M
-
1
;
n
=
0
,
1
,
…
,
N
-
1
}
,
wherein
W
1
(
mN
+
n
)
=
diag
(
D
(
:
,
1
)
)
·
v
m
,
n
,
V
m
,
n
=
1
N
t
[
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
1
)
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
2
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
i
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
N
t
)
]
T
,
D(:,1) represents the first column of the Hadamard matrix D, diag(D(:,1)) represents a diagonal matrix with main diagonal elements being the first column of the Hadamard matrix D, R represents the radius of the uniform circular array, θ i represents an azimuth angle of the i th antenna, and λ represents the wavelength of the electromagnetic wave emitted from the base station.
4. The method according to claim 3 , wherein a codebook C r of rank r among the N t codebooks is determined in the formula of:
C r ={W r (mN+n) , m= 0,1, . . . , M− 1; n= 0,1, . . . , N− 1},
wherein W r (mN+n) =X m,n (:,1:r)/√r, 1≦r≦N t , X m,n represents a N t ×N t matrix, X m,n (:,1:r) represents a matrix composed of the first to r th column vectors of the matrix X m,n , and X m,n is constructed by the equation of:
X m,n (:, k )=diag( D (:, k ))* v m,n , k= 1,2, . . . , N t ,
wherein D represents the N t ×N t Hadamard matrix with the first column which is all 1 or all −1, X m,n (:,k) represents the k th column vector of the matrix X m,n , D(:,k) represents the k th column vector of the matrix D, and diag(D(:,k)) represents a diagonal matrix with main diagonal elements being the k th column vector of the matrix D.
5. The method according to claim 3 , wherein the codeword index information comprises rank indication information and codeword indication information, and the determining comprises:
determining a target codebook corresponding to the rank indication information from the set of codebooks according to the rank indication information; and
determining the target codeword corresponding to the codeword indication information from the target codebook according to the codeword indication information.
6. A method of providing a base station with codeword index information in a user equipment of a MIMO communication system, the base station being configured with N t antennas in a uniform circular array, wherein the method comprises:
determining a codeword from a set of codebooks according to an estimated matrix and based on a predetermined criterion; and
transmitting codeword index information of the codeword to the base station,
wherein the set of codebooks comprises N t codebooks corresponding respectively to respective ranks and the N t codebooks are determined based upon a N t ×N t Hadamard matrix D and a codebook C 1 of rank 1,
wherein the first column of the Hadamard matrix D is all 1 or all −1, and the codebook of rank 1 is
C
1
=
{
W
1
(
mN
+
n
)
,
m
=
0
,
1
,
…
,
M
-
1
;
n
=
0
,
1
,
…
,
N
-
1
}
,
wherein
W
1
(
mN
+
n
)
=
diag
(
D
(
:
,
1
)
)
·
v
m
,
n
,
V
m
,
n
=
1
N
t
[
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
1
)
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
2
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
i
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
N
t
)
]
T
,
D(:,1) represents the first column of the Hadamard matrix D, diag(D(:,1)) represents a diagonal matrix with main diagonal elements being the first column of the Hadamard matrix D, R represents the radius of the uniform circular array, θ i represents an azimuth angle of the i th antenna, and λ represents the wavelength of the electromagnetic wave emitted from the base station.
7. The method according to claim 6 , wherein a codebook C r of rank r among the N t codebooks is determined in the formula of:
C r ={W r (mN+n) , m= 0,1, . . . , M− 1; n= 0,1, . . . , N− 1},
wherein W r (mN+n) =X m,n (:,1:r)/√r, 1≦r≦N t , X m,n represents a N t ×N t matrix, X m,n (:,1:r) represents a matrix composed of the first to r th column vectors of the matrix X m,n , and X m,n is constructed by the equation of:
X m,n (:, k )=diag( D (:, k ))* v m,n , k= 1,2, . . . , N t ,
wherein D represents the N t ×N t Hadamard matrix with the first column which is all 1 or all −1, X m,n (:,k) represents the k th column vector of the matrix X m,n , D(:,k) represents the k th column vector of the matrix D, and diag(D(:,k)) represents a diagonal matrix with main diagonal elements being the k th column vector of the matrix D.
8. The method according to claim 6 , wherein the codeword index information comprises rank indication information and codeword indication information.
9. The method according to claim 6 , wherein the predetermined criterion comprises a maximized capacity criterion.
10. A device for determining a codeword in a base station of a MIMO communication system, the base station being configured with N t antennas in a uniform circular array, wherein the device comprises:
a first receiver configured to receive codeword index information from a user equipment; and
a first determiner configured to receive codeword index information from the first receiver and further configured to determine a target codeword corresponding to the codeword index information from a set of codebooks according to the codeword index information,
wherein the set of codebooks comprises N t codebooks corresponding respectively to respective ranks and the N t codebooks are determined based upon a N t ×N t Hadamard matrix D and a codebook C 1 of rank 1,
wherein the first column of the Hadamard matrix D is all 1 or all −1, and the codebook of rank 1 is
C
1
=
{
W
1
(
mN
+
n
)
,
m
=
0
,
1
,
…
,
M
-
1
;
n
=
0
,
1
,
…
,
N
-
1
}
,
wherein
W
1
(
mN
+
n
)
=
diag
(
D
(
:
,
1
)
)
·
v
m
,
n
,
V
m
,
n
=
1
N
t
[
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
1
)
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
2
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
i
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
N
t
)
]
T
,
D(:,1) represents the first column of the Hadamard matrix D, diag(D(:,1)) represents a diagonal matrix with main diagonal elements being the first column of the Hadamard matrix D, R represents the radius of the uniform circular array, θ i represents an azimuth angle of the i th antenna, and λ represents the wavelength of the electromagnetic wave emitted from the base station.
11. The method according to claim 10 , wherein a codebook C r of rank r among the N t codebooks is determined in the formula of:
C r ={W r (mN+n) , m= 0,1, . . . , M− 1; n= 0,1, . . . , N− 1},
wherein W r (mN+n) =X m,n (:,1:r)/√r, 1≦r≦N t , X m,n represents a N t ×N t matrix, X m,n (:,1:r) represents a matrix composed of the first to r th column vectors of the matrix X m,n , and X m,n is constructed by the equation of:
X m,n (:, k )=diag( D (:, k ))* v m,n , k= 1,2, . . . , N t ,
wherein D represents the N t ×N t Hadamard matrix with the first column which is all 1 or all −1, X m,n (:,k) represents the k th column vector of the matrix X m,n , D(:,k) represents the k th column vector of the matrix D, and diag(D(:,k)) represents a diagonal matrix with main diagonal elements being the k th column vector of the matrix D.
12. The device according to claim 10 , wherein the codeword index information comprises rank indication information and codeword indication information, and the first determining unit is further configured to determine a target codebook corresponding to the rank indication information from the set of codebooks according to the rank indication information and for determining the target codeword corresponding to the codeword indication information from the target codebook according to the codeword indication information.
13. A device for providing a base station with codeword index information in a user equipment of a MIMO communication system, the base station being configured with N t antennas in a uniform circular array, wherein the device comprises:
a second determiner configured to determine a codeword from a set of codebooks according to an estimated channel matrix and based on a predetermined criterion and provide the codeword to a transmitter; and
wherein the transmitter is configured to transmit codeword index information of the codeword to the base station,
wherein the set of codebooks comprises N t codebooks corresponding respectively to respective ranks and the N t codebooks are determined based upon a N t ×N t Hadamard matrix D and a codebook C 1 of rank 1,
wherein the first column of the Hadamard matrix D is all 1 or all −1, and the codebook of rank 1 is
C
1
=
{
W
1
(
mN
+
n
)
,
m
=
0
,
1
,
…
,
M
-
1
;
n
=
0
,
1
,
…
,
N
-
1
}
,
wherein
W
1
(
mN
+
n
)
=
diag
(
D
(
:
,
1
)
)
·
v
m
,
n
,
V
m
,
n
=
1
N
t
[
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
1
)
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
2
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
i
)
,
…
,
ⅇ
-
j
2
π
R
λ
sin
(
π
m
M
)
cos
(
2
π
n
N
-
θ
N
t
)
]
T
,
D(:,1) represents the first column of the Hadamard matrix D, diag(D(:,1)) represents a diagonal matrix with main diagonal elements being the first column of the Hadamard matrix D, R represents the radius of the uniform circular array, θ i represents an azimuth angle of the i th antenna, and λ represents the wavelength of the electromagnetic wave emitted from the base station.
14. The method according to claim 13 , wherein a codebook C r of rank r among the N t codebooks is determined in the formula of:
C r ={W r (mN+n) , m= 0,1, . . . , M− 1; n= 0,1, . . . , N− 1},
wherein W r (mN+n) =X m,n (:,1:r)/√r, 1≦r≦N t , X m,n represents a N t ×N t matrix, X m,n (:,1:r) represents a matrix composed of the first to r th column vectors of the matrix X m,n , and X m,n is constructed by the equation of:
X m,n (:, k )=diag( D (:, k ))* v m,n , k= 1,2, . . . , N t ,
wherein D represents the N t ×N t Hadamard matrix with the first column which is all 1 or all −1, X m,n (:,k) represents the k th column vector of the matrix X m,n , D(:,k) represents the k th column vector of the matrix D, and diag(D(:,k)) represents a diagonal matrix with main diagonal elements being the k th column vector of the matrix D.
15. The device according to claim 13 , wherein the codeword index information comprises rank indication information and codeword indication information.