Methods and Devices for Mitigating Interference

• US 20140321296A1
• Filed: 04/26/2013
• Published: 10/30/2014
• Est. Priority Date: 04/26/2013
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Deutschland GmbH (Intel Corporation)
• Inventors: Balraj, Rajarajan
• Granted Patent: US 9,571,242 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04J 11/005 of intercell interference
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

A method includes receiving a signal including a two-dimensional signal pattern in a time-frequency representation, wherein the two-dimensional signal pattern includes a first reference signal at a predetermined first position in the two-dimensional signal pattern and at least one second reference signal at a predetermined second position in the two-dimensional signal pattern. The first reference signal includes cell identification information of a target cell of a cellular radio system and the at least one second reference signal includes cell identification information of at least one interfering cell of the cellular radio system. The method further includes determining a first noise covariance measure based on the first reference signal, determining at least one second noise covariance measure based on the at least one second reference signal, and mitigating an interference included in the received signal based on the first noise covariance measure and the at least one second noise covariance measure.

Claims

1. A method, comprising:

receiving a signal comprising a two-dimensional signal pattern in a time-frequency representation, wherein the two-dimensional signal pattern comprises a first reference signal at a predetermined first position in the two-dimensional signal pattern and at least one second reference signal at a predetermined second position in the two-dimensional signal pattern, wherein the first reference signal comprises cell identification information of a target cell of a cellular radio system and the at least one second reference signal comprises cell identification information of at least one interfering cell of the cellular radio system;

determining a first noise covariance measure based on the first reference signal;

determining at least one second noise covariance measure based on the at least one second reference signal; and

mitigating an interference comprised in the received signal based on the first noise covariance measure and the at least one second noise covariance measure.

2. The method of claim 1, wherein the first reference signal and the at least one second reference signal comprise cell-specific reference signals.

3. The method of claim 1, wherein mitigating the interference comprises at least one of the following operations with respect to the received signal:

noise-whitening, interference rejection combining, and minimum mean square error estimation.

4. The method of claim 1, wherein the first reference signal comprises a first part corresponding to a first antenna port of a plurality of antenna ports of the target cell and a second part corresponding to a second antenna port of the plurality of antenna ports of the target cell, and wherein the at least one second reference signal comprises a first part corresponding to a first antenna port of a plurality of antenna ports of the interfering cell and a second part corresponding to a second antenna port of the plurality of antenna ports of the interfering cell.

5. The method of claim 4, wherein the position of the first part of the at least one second reference signal in the two-dimensional signal pattern is spaced apart by a predetermined frequency shift from the position of the first part of the first reference signal in the two-dimensional signal pattern, wherein the predetermined frequency shift corresponds to an interfering cell.

6. The method of claim 5, wherein the position of the second part of the at least one second reference signal in the two-dimensional signal pattern is spaced apart by the predetermined frequency shift from the position of the second part of the first reference signal in the two-dimensional signal pattern.

7. The method of claim 1, wherein each of the at least one second reference signal corresponds to an interfering cell.

8. The method of claim 5, wherein the predetermined frequency shift corresponds to multiple interfering cells.

9. The method of claim 5, further comprising:

determining the first noise covariance measure based on pilot signals of the target cell;

noise whitening first elements of the two-dimensional signal pattern located at a predetermined third position in the two-dimensional signal pattern indicating data resource elements of the target cell with no cell-specific reference signal interference and noise whitening channel estimates of the target cell corresponding to the first elements, wherein the noise whitening is based on the first noise covariance measure;

determining channel coefficients of an interfering cell with respect to the corresponding antenna port and frequency shift of the interfering cell;

determining the at least one second noise covariance measure with respect to an antenna port and a frequency shift of the interfering cell based on the estimated channel coefficients with respect to the corresponding antenna port and frequency shift of the interfering cell; and

noise whitening second elements of the two-dimensional signal pattern located at a predetermined fourth position in the two-dimensional signal pattern indicating data resource elements of the target cell hit with cell-specific reference signal interference and noise whitening channel estimates of the target cell corresponding to the second elements, wherein the noise whitening is based on the at least one second noise covariance measure.

10. The method of claim 9, wherein determining the at least one second noise covariance measure and noise whitening the at least one second reference signal is performed for each antenna port and frequency shift unequal to an antenna port and a frequency shift corresponding to the target cell.

11. The method of claim 5, further comprising:

determining the first noise covariance measure based on pilot signals of the target cell;

noise whitening first elements of the two-dimensional signal pattern located at a predetermined third position in the two-dimensional signal pattern indicating data resource elements of the target cell with no cell-specific reference signal interference and noise whitening channel estimates of the target cell corresponding to the first elements, wherein the noise whitening is based on the first noise covariance measure;

determining the at least one second noise covariance measure with respect to an antenna port and a frequency shift of the interfering cell based on the at least one second reference signal with respect to the corresponding antenna port and frequency shift of the interfering cell and estimated channel coefficients of the target cell; and

noise whitening second elements of the two-dimensional signal pattern located at a predetermined fourth position in the two-dimensional signal pattern indicating data resource elements of the target cell hit with cell-specific reference signal interference and noise whitening channel estimates of the target cell corresponding to the second elements, wherein the noise whitening is based on the at least one second noise covariance measure.

12. The method of claim 11, wherein determining the at least one second noise covariance measure and noise whitening the at least one second reference signal is performed for each antenna port and frequency shift unequal to an antenna port and a frequency shift corresponding to the target cell.

13. The method of claim 11, wherein the channel coefficients of the target cell are estimated based on a known pre-coding matrix.

14. The method of claim 5, further comprising:

determining the first noise covariance measure based on pilot signals of the target cell;

noise whitening first elements of the two-dimensional signal pattern located at a predetermined third position in the two-dimensional signal pattern indicating data resource elements of the target cell with no cell-specific reference signal interference and noise whitening channel estimates of the target cell corresponding to the first elements, wherein the noise whitening is based on the first noise covariance measure;

determining channel coefficients of a predetermined number of interfering cells with respect to the corresponding antenna ports and frequency shifts of the interfering cells;

interference-canceling the at least one second reference signal with respect to the corresponding antenna ports and frequency shifts of the interfering cells based on the determined channel coefficients of the interfering cells;

determining the at least one second noise covariance measure with respect to an antenna port and a frequency shift of the interfering cell based on the data resource elements of the target cell where the interference-canceling is performed with respect to the corresponding antenna port and frequency shift of the interfering cell; and

noise whitening second elements of the two-dimensional signal pattern located at a predetermined fourth position in the two-dimensional signal pattern indicating data resource elements of the target cell hit with cell-specific reference signal interference and noise whitening channel estimates of the target cell corresponding to the second elements, wherein the noise whitening is based on the at least one second noise covariance measure.

15. The method of claim 14, wherein determining the channel coefficients of the predetermined number of interfering cells, interference-canceling the at least one second reference signals, determining the at least one second noise covariance measure and noise whitening the second elements of the two-dimensional signal pattern is performed for each antenna port and frequency shift unequal to an antenna port and a frequency shift corresponding to the target cell.

16. The method of claim 14, wherein the predetermined number of interfering cells with respect to an antenna port and frequency shift is smaller than a number of dominant aggressor cells with respect to the corresponding antenna port and frequency shift.

17. A device, comprising:

a first unit configured to receive a signal comprising a two-dimensional signal pattern in a time-frequency representation, wherein the two-dimensional signal pattern comprises a first reference signal at a predetermined first position in the two-dimensional signal pattern and at least one second reference signal at a predetermined second position in the two-dimensional signal pattern, wherein the first reference signal comprises cell identification information of a target cell of a cellular radio system and the at least one second reference signal comprises cell identification information of at least one interfering cell of the cellular radio system;

a second unit configured to determine a first noise covariance measure based on the first reference signal;

a third unit configured to determine at least one second noise covariance measure based on the at least one second reference signal; and

a fourth unit configured to mitigate an interference comprised in the received signal based on the first noise covariance measure and the at least one second noise covariance measure.

18. The device of claim 17, wherein the device comprises a chip, and the device is part of a mobile device.

19. A method, comprising:

receiving a signal comprising a two-dimensional signal pattern in a time-frequency representation, wherein the two-dimensional signal pattern comprises a first reference signal at a predetermined first position in the two-dimensional signal pattern and at least one second reference signal at a predetermined second position in the two-dimensional signal pattern, wherein the first position represents an antenna port and a frequency shift of a target cell of a cellular radio system and the second position represents an antenna port and a frequency shift of at least one interfering cell of the cellular radio system;

determining a first noise covariance measure based on pilot signals of the target cell;

determining channel coefficients of a predetermined number of interfering cells with respect to corresponding antenna ports and frequency shifts of the interfering cells;

interference-canceling the at least one second reference signal with respect to the corresponding antenna ports and frequency shifts of the interfering cells based on the determined channel coefficients of the interfering cells;

determining at least one second noise covariance measure with respect to an antenna port and a frequency shift of the interfering cell based on data resource elements comprised in the received signal where the interference-canceling is performed with respect to the corresponding antenna port and frequency shift of the interfering cell; and

mitigating an interference comprised in the received signal based on the first noise covariance measure and the at least one second noise covariance measure.

20. The method of claim 19, wherein the target cell comprises at least one of a macro base station, a pico cell, a femto cell, and a relay.