Method and device for detecting signal of LTE uplink system in interference condition
View Patent ↗A method and device for detecting a signal of an LTE uplink system in an interference condition. The method comprises: receiving baseband signals of M receiving antennas, and after fast Fourier transform, conducting demapping to obtain frequency-domain baseband signals; extracting a DMRS inserted in a received signal of each antenna, and then, calculating a channel gain h l,k of each receiving antenna; combining the baseband signals and the channel gains of the M receiving antennas to obtain a signal matrix Y k and a gain matrix H k ; calculating an interference noise covariance matrix R k on each subcarrier; conducting interference pre-processing on a received signal on each combined subcarrier to obtain the received signal (1) and the channel gain (2) after the interference pre-processing, where D=R k −1/2 ; and according to (3), conducting frequency-domain balancing on the received signal after the interference pre-processing.
1. A signal detection method, applied in a Long Term Evolution (LTE) uplink system equipped with one transmission antenna and M reception antennas in an interference condition, the method comprising:
receiving baseband signals of the M reception antennas, and performing Fast Fourier Transform and de-mapping on the received baseband signals to obtain frequency-domain baseband signals y l,k ,1≤l≤M,1≤k≤N s , where the l denotes an Ith reception antenna, the k denotes a sequence number of a sub-carrier, and the N s denotes a number of sub-carriers occupied by a user equipment actually;
extracting an LTE uplink demodulation reference signal (DMRS) inserted in the signals received by each of the reception antennas, and then calculating a channel gain h l,k of each of the reception antennas;
combining the baseband signals and the channel gains of the M reception antennas to obtain a signal matrix Y k and a gain matrix H k ;
calculating an interference noise covariance matrix R k of each sub-carrier;
performing interference pre-processing on the combined received signal on each sub-carrier, so as to obtain the received signals subjected to the interference pre-processing {tilde over (Y)} k =DY k , and the channel gains subjected to the interference pre-processing {tilde over (H)} k =DH k , wherein D=R k −1/2 ;
performing frequency-domain equalization on the received signals subjected to the interference pre-processing, based on the {tilde over (H)} k .
2. The method according to claim 1 , wherein, the step of extracting an LTE uplink DMRS inserted in the signal received by each of the reception antennas, and calculating a channel gain h l,k of each of the reception antennas, comprises:
extracting the uplink DMRS y l dmrs inserted in the signals received by each of the reception antennas, wherein the l denotes an Ith reception antenna;
performing least square (LS) estimation on the y l dmrs , so as to obtain an LS estimation output vector h LS =X −1 y l dmrs , wherein the X is the uplink DMRS;
calculating a frequency-domain correlation matrix of a time-domain rectangular window by using a formula:
R
^
=
F
N
E
{
gg
H
}
F
N
H
=
F
N
diag
(
N
Q
[
1
,
…
,
1
︸
Q
,
0
,
…
,
0
]
)
F
N
H
,
wherein the F N is an N×N Discrete Fourier Transform (DFT) matrix, the N is a number of the sub-carriers, the g is the time-domain rectangular window, the Q is a window length with a value less than an length of a cyclic prefix;
calculating the frequency-domain correlation matrix of the sub-carriers occupied by the user equipment actually by using a formula:
R
_
N
s
=
(
F
N
diag
(
N
Q
[
1
,
…
,
1
︸
Q
,
0
,
…
,
0
]
)
F
N
H
)
1
:
N
s
,
1
:
N
s
,
performing eigen value decomposition on the R N s by using a formula: R N s =U h ΛU h H ; and
performing windowing processing on the LS estimation output vector in an eigen domain of the R N s by using a formula:
h
l
=
U
h
{
diag
(
[
1
,
…
,
1
︸
Q
1
,
0
,
…
,
0
]
)
}
U
h
H
h
LS
,
wherein the Q 1 denotes a length of the rectangular window and a value of the Q 1 denotes a number of non-zero elements of a diagonal matrix Λ.
3. The method according to claim 1 , wherein the signal matrix Y k and the gain matrix H k obtained through the step of combining are Y k =[y 1,k , . . . , y M,k ] T and H k =[h 1,k , . . . , h M,k ] T respectively.
4. The method according to claim 1 , wherein the step of calculating an interference noise covariance matrix R k of each sub-carrier comprises:
extracting, from the combined signals, the uplink DMRS Y k dmrs of each sub-carrier; and
calculating the interference noise covariance matrix R k of each sub-carrier according to the following formula:
R
k
=
1
K
∑
m
=
⌊
k
/
K
⌋
×
K
+
1
⌊
k
/
K
⌋
×
K
+
K
(
Y
m
dmrs
-
H
m
X
m
)
(
Y
m
dmrs
-
H
m
X
m
)
H
,
wherein the K denotes an accumulated number of sub-carriers, and the └ ┘ denotes a floor operation.
5. The method according to claim 1 , wherein the step of performing an interference pre-processing on the combined received signals on each sub-carrier after the step of combining comprises:
calculating a pre-processing matrix D, comprising:
performing eigen value decomposition on the interference noise covariance matrix of each sub-carrier by using a formula: R k =UVU H =(UV 1/2 U H )·(UV 1/2 U H ) H , wherein the Λ denotes an diagonal matrix, the U denotes a unitary matrix, and the Λ 1/2 denotes a rooting operation on diagonal elements of the matrix Λ; and
assuming D =R k −1/2 =UΛ −1/2 U H ; and
performing a whitening operation, comprising:
multiplying the D by the received signal on each sub-carrier to obtain {tilde over (Y)} k =DY k =DH k s k +Du k , wherein the s k denotes a transmission signal on a kth sub-carrier, the u k denotes an interference noise vector of the kth sub-carrier, and the channel matrix subjected to the interference pre-processing is {tilde over (H)} k =DH k .
6. The method according to claim 5 , wherein the step of performing frequency-domain equalization on the reception signals subjected to the interference pre-processing, based on the {tilde over (H)} k , comprises:
calculating a weight vector w of frequency-domain equalization, and combining the received signals {tilde over (Y)} k subjected to the interference pre-processing, wherein w={tilde over (H)} k H ({tilde over (H)} k {tilde over (H)} k H +I) −1 .
7. A signal detection device, applied in a Long Term Evolution (LTE) uplink system equipped with one transmission antenna and M reception antennas in an interference condition, the device comprising:
a processor; and
a memory storing instructions executable by the processor;
wherein the processor is arranged to:
receive baseband signals of the M reception antennas, and perform Fast Fourier Transform and de-mapping on the received baseband signals to obtain frequency-domain baseband signals y l,k ,1≤l≤M,1≤k≤N s , wherein the l denotes an Ith reception antenna, the k denotes a sequence number of a sub-carrier, and the N s denotes a number of sub-carriers occupied by a user equipment actually;
extract an LTE uplink demodulation reference signal (DMRS) inserted in the signal received by each of the reception antennas, and then calculate a channel gain h l,k of each of the reception antennas;
combine the baseband signals and the channel gains of the M reception antennas to obtain a signal matrix Y k and a gain matrix H k ;
calculate an interference noise covariance matrix R k of each sub-carrier;
perform interference pre-processing on the combined received signal on each sub-carrier, so as to obtain the received signals subjected to the interference pre-processing {tilde over (Y)} k =DY k , and the channel gains subjected to the interference pre-processing {tilde over (H)} k =DH k , wherein D=R k −1/2 ; and
perform frequency-domain equalization on the received signals subjected to the interference pre-processing, based on the {tilde over (H)} k .
8. The device according to claim 7 , wherein in order to extract the LTE uplink DMRS, the processor is arranged to:
extract the uplink DMRS y l dmrs inserted in the signals received by each of the reception antennas, wherein the l denotes an Ith reception antenna;
perform LS estimation on the y l dmrs , so as to obtain an LS estimation output vector h LS =X −1 y l dmrs , wherein the X denotes the uplink DMRS;
calculate a frequency-domain correlation matrix of a time-domain rectangular window by using a formula:
R
^
=
F
N
E
{
gg
H
}
F
N
H
=
F
N
diag
(
N
Q
[
1
,
…
,
1
︸
Q
,
0
,
…
,
0
]
)
F
N
H
,
wherein the F N denotes an N×N Discrete Fourier Transform (DFT) matrix, the N denotes a number of the sub-carriers, the g denotes the time-domain rectangular window, the Q denotes a window length with a value less than an length of a cyclic prefix;
calculate the frequency-domain correlation matrix of the sub-carriers occupied by the user equipment actually by using a formula:
R
_
N
s
=
(
F
N
diag
(
N
Q
[
1
,
…
,
1
︸
Q
,
0
,
…
,
0
]
)
F
N
H
)
1
:
N
s
,
1
:
N
s
,
perform eigen value decomposition on the R N s by using a formula: R N s =U h ΛU h H ; and
perform windowing processing on the LS estimation output vector in an eigen domain of the R N s by using a formula:
h
l
=
U
h
{
diag
(
[
1
,
…
,
1
︸
Q
1
,
0
,
…
,
0
]
)
}
U
h
H
h
LS
,
wherein the Q 1 denotes a length of the rectangular window and a value of the Q 1 denotes a number of non-zero elements of a diagonal matrix Λ.
9. The device according to claim 7 , wherein the signal matrix Y k and the gain matrix H k are Y k =[y 1,k , . . . , y M,k ] T and H k =[h 1,k , . . . , h M,k ] T respectively.
10. The device according to claim 7 , wherein in order to calculate the interference noise covariance matrix R k of each sub-carrier, the processor is arranged to:
extract, from the combined signals, the uplink DMRS Y k dmrs of each sub-carrier; and
calculate an interference noise covariance matrix R k of each sub-carrier according to the following formula:
R
k
=
1
K
∑
m
=
⌊
k
/
K
⌋
×
K
+
1
⌊
k
/
K
⌋
×
K
+
K
(
Y
m
dmrs
-
H
m
X
m
)
(
Y
m
dmrs
-
H
m
X
m
)
H
,
wherein the K denotes an accumulated number of sub-carriers, and the └ ┘ denotes a floor operation.
11. The device according to claim 7 , wherein in order to perform interference pre-processing on the combined received signal on each sub-carrier, the processor is arranged to:
perform eigen value decomposition on the interference noise covariance matrix of each sub-carrier by using a formula: R k =UVU H =(UV 1/2 U H )·(UV 1/2 U H ) H , and assume D=R k −1/2 =UΛ −1/2 U H , wherein the Λ denotes an diagonal matrix, the U denotes a unitary matrix, and the Λ 1/2 denotes a rooting operation on diagonal elements of the matrix Λ;
multiply the D by the received signal on each sub-carrier to obtain {tilde over (Y)}=DY k =DH k s k +Du k , wherein the s k denotes a transmission signal on a kth sub-carrier, the u k denotes an interference noise vector of the kth sub-carrier, and the channel matrix subjected to the interference pre-processing is {tilde over (H)} k =DH k .
12. The device according to claim 11 , wherein the processor is further arranged to calculate a weight vector w of frequency-domain equalization, and combine the received signals {tilde over (Y)} k subjected to the interference pre-processing, wherein w={tilde over (H)} k H ({tilde over (H)} k {tilde over (H)} k H +I) −1 .
13. A non-transitory computer storage medium storing computer-executable instructions for performing a signal detection method, applied in a Long Term Evolution (LTE) uplink system equipped with one transmission antenna and M reception antennas in an interference condition the method comprising:
receiving baseband signals of the M reception antennas, and performing Fast Fourier Transform and de-mapping on the received baseband signals to obtain frequency-domain baseband signals y l,k ,1≤l≤M,1≤k≤N s , where the l denotes an Ith reception antenna, the k denotes a sequence number of a sub-carrier, and the N s denotes a number of sub-carriers occupied by a user equipment actually;
extracting an LTE uplink demodulation reference signal (DMRS) inserted in the signal received by each of the reception antennas, and then calculating a channel gain h l,k of each of the reception antennas;
combining the baseband signals and the channel gains of the M reception antennas to obtain a signal matrix Y k and a gain matrix H k ;
calculating an interference noise covariance matrix R k on each sub-carrier;
performing interference pre-processing on the combined received signal on each sub-carrier, so as to obtain the received signals subjected to the interference pre-processing {tilde over (Y)} k =DY k , and the channel gains subjected to the interference pre-processing {tilde over (H)} k =DH k , wherein D=R k −1/2 ; and
performing frequency-domain equalization on the received signals subjected to the interference pre-processing, based on the {tilde over (H)} k .
14. The non-transitory computer storage medium according to claim 13 , wherein the step of extracting an LTE uplink DMRS inserted in the signal received by each of the reception antennas, and calculating a channel gain h l,k of each of the reception antennas comprises:
extracting the uplink DMRS y l dmrs inserted in the signals received by each of the reception antennas, wherein the l denotes an Ith reception antenna;
performing least square (LS) estimation on the y l dmrs so as to obtain an LS estimation output vector h LS =X −1 y l dmrs , wherein the X is the uplink DMRS;
calculating a frequency-domain correlation matrix of a time-domain rectangular window by using a formula:
R
^
=
F
N
E
{
gg
H
}
F
N
H
=
F
N
diag
(
N
Q
[
1
,
…
,
1
︸
Q
,
0
,
…
,
0
]
)
F
N
H
wherein the F N is an N×N Discrete Fourier Transform (DFT) matrix, the N is a number of the sub-carriers, the g is the time-domain rectangular window, Q is a window length with a value less than an length of a cyclic prefix;
calculating the frequency-domain correlation matrix of the sub-carriers occupied by the user equipment actually by using a formula:
R
_
N
s
=
(
F
N
diag
(
N
Q
[
1
,
…
,
1
︸
Q
,
0
,
…
,
0
]
)
F
N
H
)
1
:
N
s
,
1
:
N
s
performing eigen value decomposition on the R N s by using a formula: R N s =U h ΛU h H ; and
performing windowing processing on the LS estimation output vector in an eigen domain of the R N s by using a formula:
h
l
=
U
h
{
diag
(
[
1
,
…
,
1
︸
Q
1
,
0
,
…
,
0
]
)
}
U
h
H
h
LS
wherein the Q 1 is a length of the rectangular window and a value of the Q 1 is a number of non-zero elements of a diagonal matrix Λ.
15. The non-transitory computer storage medium according to claim 13 , wherein the signal matrix Y k and the gain matrix H k obtained through the step of combining are Y k =[y 1,k , . . . , y M,k ] T and H k =[h 1,k , . . . , h M,k ] T respectively.
16. The non-transitory computer storage medium according to claim 13 , wherein, the step of calculating an interference noise covariance matrix R k on each sub-carrier comprises:
extracting, from the combined signals, the uplink DMRS Y k dmrs of each sub-carrier; and
calculating the interference noise covariance matrix R k of each sub-carrier according to the following formula:
R
k
=
1
K
∑
m
=
⌊
k
/
K
⌋
×
K
+
1
⌊
k
/
K
⌋
×
K
+
K
(
Y
m
dmrs
-
H
m
X
m
)
(
Y
m
dmrs
-
H
m
X
m
)
H
wherein the K denotes an accumulated number of sub-carriers, and the └ ┘ denotes a floor operation.
17. The non-transitory computer storage medium according to claim 13 , wherein the step of performing an interference pre-processing on the combined received signals on each sub-carrier after the step of combining comprises:
calculating a pre-processing matrix D, comprising:
performing eigen value decomposition on the interference noise covariance matrix of each sub-carrier by using a formula: R k =UVU H =(UV 1/2 U H )·(UV 1/2 U H ) H , wherein the Λ is an diagonal matrix, the U is a unitary matrix, and the Λ 1/2 is a rooting operation on diagonal elements of the matrix Λ; and
assuming D=R k −1/2 =UΛ −1/2 U H ; and
performing a whitening operation, comprising:
multiplying D by the received signal on each sub-carrier to obtain {tilde over (Y)} k =DY k =DH k s k +Du k , wherein the s k denotes a transmission signal on a sub-carrier k, the u k denotes an interference noise vector of the kth sub-carrier, and the channel matrix subjected to the interference pre-processing is {tilde over (H)} k =DH k .
18. The non-transitory computer storage medium according to claim 17 , wherein the step of performing frequency-domain equalization on the reception signals subjected to the interference pre-processing, based on the {tilde over (H)} k comprises:
calculating a weight vector w of frequency-domain equalization, and combining the received signals {tilde over (Y)} k subjected to the interference pre-processing, wherein the w is calculated by using a formula: w={tilde over (H)} k H ({tilde over (H)} k {tilde over (H)} k H +I) −1 .