Method and device for interference cancellation
View Patent ↗An interference cancellation method performed by a receiver includes: determining a strong interference code channel among all code channels that carry a received signal, and determining a signal that corresponds to the strong interference code channel to be a strong interference signal, wherein the received signal has been matched filtered. The method further includes obtaining a reconstructed strong interference signal based on the determined strong interference signal and using a system matrix, performing the interference cancellation for the received signal using the reconstructed strong interference signal, to obtain the signal without interference. The strong interference signal can be reconstructed using the system matrix, and the interference cancellation can be performed for the received signal using the reconstructed strong interference signal. The complexity of inverting the matrix is reduced and the performance is enhanced by reducing the order of the matrix, and thus increasing the efficiency of cancelling the interference.
1. An interference cancellation method in a receiver, the method comprising:
determining a strong interference code channel among all code channels that carry a received signal, and determining a signal that corresponds to the strong interference code channel to be a strong interference signal by a receiver, wherein the received signal is a signal that has been matched filtered;
obtaining a reconstructed strong interference signal based on the determined strong interference signal using a system matrix; and
performing the interference cancellation for the received signal by utilizing the reconstructed strong interference signal, to obtain the received signal without interference,
wherein the reconstructed strong interference signal is determined by the following equation:
{circumflex over (d)} SI = diag (A H A)e mf,SI
wherein e mf,SI is the strong interference signal, A is the system matrix, diag (.) is a matrix generated by setting diagonal elements into 0,
wherein,
e
mf
,
SI
=
{
0
…
0
︸
K
vru
0
…
0
︸
K
vru
︷
44
*
(
Kvru
-
n
)
…
e
mf
,
1
(
SI
1
)
…
e
mf
,
44
(
SI
1
)
…
e
mf
,
1
(
SIn
)
…
e
mf
,
44
(
SIn
)
}
,
Kvru being the total number of the code channels, e mf,i (SI1) being the j-th element in the code channel of the i-th strong interference signal, and n beinq the number of the strong interference code channels.
2. The interference cancellation method according to claim 1 , wherein after performing the interference cancellation to obtain the received signal without the interference, the method further comprises:
setting a column that corresponds to a sequence number of the strong interference code channel in the system matrix into 0 to obtain a clipped matrix;
performing an equalization operation for the received signal without the interference using the clipped matrix by the receiver.
3. The interference cancellation method according to claim 1 , wherein the determining of the strong interference code channel comprises:
determining a first power value of each code channel,
comparing the first power value with a second power value of a code channel of a local user, and determining the code channel to be the strong interference code channel if a ratio of the first power value and the second power value is larger than or equal to a predetermined value.
4. The interference cancellation method according to claim 3 , wherein the power value P (k) of the k-th code channel is determined by the following equation:
P
(
k
)
=
∑
i
=
1
X
e
mf
,
i
(
k
)
2
wherein e mf,i (k) is the i-th symbol of the k-th code channel for the received signal output by a matched filter, and X is the number of symbols of each code channel.
5. The interference cancellation method according to claim 1 , wherein the received signal without the interference is determined by the following equation:
{circumflex over (d)} MFIC =(diag( A H A)) −1 e mf,PS −(diag( A H A)) −1 {circumflex over (d)} SI
wherein, (.) −1 is the matrix inversion, diag(.) is a matrix generated by setting non-diagonal elements into 0, e mf,SI is the strong interference signal, and e mf,PS is a signal generated by sequencing the powers of all code channels in an ascending sequence.
6. An interference cancellation apparatus, comprising:
an interference detection module, being configured for determining a strong interference code channel among all code channels that carry a received signal, and determining a signal that corresponds to the strong interference code channel to be a strong interference signal, wherein the received signal is a signal that has been matched filtered;
a reconstruction module, being configured for obtaining a reconstructed strong interference signal based on the determined strong interference signal using a system matrix; and
an interference cancellation module, being configured for performing the interference cancellation for the received signal by utilizing the reconstructed strong interference signal, to obtain the received signal without interference,
wherein the reconstructed strong interference signal is determined by the following equation:
{circumflex over (d)} SI = diag ( A H A ) e mf,SI
wherein e mf,SI is the strong interference signal, A is the system matrix, diag (.) is a matrix generated by setting diagonal elements into 0,
wherein,
e
mf
,
SI
=
{
0
…
0
︸
K
vru
0
…
0
︸
K
vru
︷
44
*
(
Kvru
-
n
)
…
e
mf
,
1
(
Sl
1
)
…
e
mf
,
44
(
S
l
1
)
…
e
mf
,
1
(
S
l
n
)
…
e
mf
,
44
(
S
l
n
)
}
,
Kvru being the total number of the code channels, e mf,i (SI1) being the j-th element in the code channel of the i-th strong interference signal, and n being the number of the strong interference code channels.
7. The interference cancellation apparatus according to claim 6 , wherein the apparatus further comprises:
an interference code channel determining module, being configured for determining a first power value of each code channel,
comparing the first power value with a second power value of a code channel of a local user, and
determining the code channel to be the strong interference code channel if a ratio of the first power value and the second power value is larger than or equal to a predetermined value.
8. The interference cancellation apparatus according to claim 6 , wherein the apparatus further comprises:
a matrix clipping module, being configured for setting a column that corresponds to a sequence number of the strong interference code channel in the system matrix into 0 to obtain a clipped matrix.
9. The interference cancellation apparatus according to claim 8 , wherein the apparatus further comprises:
an equalization processing module, being configured for performing an equalization operation for signals without interference on the strong interference code channel using the clipped matrix.