Systems and methods for suppressing interference in a signal received by a device having two or more antennas
Systems and methods for suppressing interference from a data signal received at a receiving device, where the receiving device has two or more receive antennas, are provided. Characteristics of a channel are estimated, the channel being a channel through which the data signal was transmitted by a transmitting device to the receiving device. A spatial correlation of interference and noise received at the two or more receive antennas of the receiving device is determined based on the estimated characteristics of the channel. The spatial correlation indicates how the interference and noise received at a particular one of the receive antennas is related to the interference and noise received at another one of the receive antennas. The spatial correlation of the interference and noise is used to suppress interference and noise from the data signal received at the receiving device.
1. A method for suppressing interference from a data signal received at a receiving device, the receiving device having two or more receive antennas, the method comprising:
estimating characteristics of a channel through which the data signal was transmitted by a transmitting device to the receiving device;
determining, based on the estimated characteristics of the channel, a spatial correlation of interference and noise received at the two or more receive antennas of the receiving device, the spatial correlation indicating how the interference and noise received at a particular one of the receive antennas is related to the interference and noise received at another one of the receive antennas; and
using the spatial correlation of the interference and noise to suppress interference and noise from the data signal received at the receiving device.
2. The method of claim 1 , wherein determining the spatial correlation of the interference and noise comprises determining a spatial covariance matrix for the interference and noise at the two or more receive antennas.
3. The method of claim 2 , wherein the characteristics of the channel are estimated based on a transmission of a plurality of pilot sequences including known reference data from the transmitting device to the receiving device, and wherein the estimated characteristics of the channel are used to determine an interference and noise matrix associated with the two or more receive antennas.
4. The method of claim 3 , wherein the spatial covariance matrix is determined according to a summation performed across the plurality of pilot sequences:
=
∑
pilots
q
^
q
^
H
,
where is the spatial covariance matrix, {circumflex over (q)} is the interference and noise matrix associated with the two or more receive antennas, and superposition ( ) H is an operation of Hermitian transpose of a complex matrix.
5. The method of claim 2 , wherein the characteristics of the channel are estimated based on a transmission of a plurality of pilot sequences including known reference data from the transmitting device to the receiving device, and wherein the estimated characteristics of the channel include an interference channel matrix, the interference channel matrix including characteristics of a channel configured for transmission of interference to the receiving device.
6. The method of claim 5 , wherein the spatial covariance matrix is determined according to a summation performed across the plurality of pilot sequences:
=
∑
pilots
H
mi
H
mi
H
+
R
^
z
,
where is the spatial covariance matrix, H mi is the interference channel matrix, is the noise covariance matrix, and superposition ( ) H is an operation of Hermitian transpose of a complex matrix.
7. The method of claim 5 , wherein the interference channel matrix is determined using a least squares approach.
8. The method of claim 2 , wherein the spatial covariance matrix is determined according to:
= {circumflex over (R)} interference-noise-matrix +{circumflex over (R)} interference-channel ,
wherein is the spatial covariance matrix, {circumflex over (R)} interference-noise-matrix is a spatial interference and noise covariance matrix determined from interference and noise, and {circumflex over (R)} interference-channel is a spatial interference covariance matrix determined from interference channels.
9. The method of claim 2 , wherein the spatial covariance matrix is determined according to
= {circumflex over (R)} intercell +{circumflex over (R)} intracell ,
wherein is the spatial covariance matrix, {circumflex over (R)} intercell is a spatial interference and noise covariance matrix determined for the interference and noise not from the transmitting device, and {circumflex over (R)} intracell is a spatial interference covariance matrix determined for the interference from the transmitting device.
10. The method of claim 2 , wherein using the spatial correlation of the interference to suppress interference from the signal comprises filtering the signal using an interference rejection filter W determined according to:
W= ( ) −1/2 ,
where {circumflex over (R)}{circumflex over (R 1 )} is the spatial covariance matrix.
11. A system for suppressing interference from a data signal received at a receiving device, the receiving device having two or more receive antennas, the system comprising:
a channel estimation block configured to estimate characteristics of a channel through which the data signal was transmitted by a transmitting device to the receiving device;
a spatial correlation block configured to determine, based on the estimated characteristics of the channel, a spatial correlation of interference and noise received at the two or more receive antennas of the receiving device, the spatial correlation indicating how the interference and noise received at a particular one of the receive antennas is related to the interference and noise received at another one of the receive antennas; and
a filtering block configured to use the spatial correlation of the interference and noise to suppress interference and noise from the data signal received at the receiving device.
12. The system of claim 11 , wherein the spatial correlation block is configured to determine a spatial covariance matrix for interference and noise at the two or more receive antennas.
13. The system of claim 12 , wherein the channel estimation block estimates the characteristics of the channel based on a transmission of a plurality of pilot sequences including known reference data from the transmitting device to the receiving device, and wherein the channel estimation block uses the estimated characteristics of the channel to determine an interference and noise matrix associated with the two or more receive antennas.
14. The system of claim 13 , wherein the spatial correlation block determines the spatial covariance matrix according to a summation performed across the plurality of pilot sequences:
=
∑
pilots
q
^
q
^
H
,
where is the spatial covariance matrix, {circumflex over (q)} is the interference and noise matrix associated with the two or more receive antennas, and superposition ( ) H is an operation of Hermitian transpose of a complex matrix.
15. The system of claim 12 , wherein the channel estimation block estimates the characteristics of the channel based on a transmission of a plurality of pilot sequences including known reference data from the transmitting device to the receiving device, and wherein the estimated characteristics of the channel include an interference channel matrix, the interference channel matrix including characteristics of a channel configured for transmission of interference to the receiving device.
16. The system of claim 15 , wherein the spatial correlation block determines the spatial covariance matrix according to a summation performed across the plurality of pilot sequences:
=
∑
pilots
H
mi
H
mi
H
+
R
^
z
,
where is the spatial covariance matrix, H mi is the interference channel matrix, is the noise covariance matrix, and superposition ( ) H is an operation of Hermitian transpose of a complex matrix.
17. The system of claim 15 , wherein the interference channel matrix is determined using a least squares approach.
18. The system of claim 12 , wherein the spatial correlation block determines the spatial covariance matrix according to:
= {circumflex over (R)} interference-noise-matrix +{circumflex over (R)} interference-channel ,
wherein is the spatial covariance matrix, {circumflex over (R)} interference-noise-matrix is a spatial interference and noise covariance matrix determined from interference and noise, and {circumflex over (R)} interference-channel is a spatial covariance matrix determined from the interference channels.
19. The system of claim 12 , wherein the spatial correlation block determines the spatial covariance matrix according to
= {circumflex over (R)} intercell +{circumflex over (R)} intracell ,
wherein is the spatial covariance matrix, {circumflex over (R)} intercell is a spatial interference and noise covariance matrix determined for the interference and noise not from the transmitting device, and {circumflex over (R)} intracell is a spatial interference covariance matrix determined for the interference from the transmitting device.
20. The system of claim 12 , wherein the filtering block filters the signal using an interference rejection filter W determined according to:
W= ( ) −1/2 ,
where is the spatial covariance matrix.