Method and apparatus for interference estimation in wireless communication networks

1. An apparatus, comprising:

a non-transitory memory configured to store program code instructions; and

a processor coupled to the memory, wherein the program code instructions, when executed by the processor, cause the processors to:

receive a digital communication signal, wherein the digital communication signal comprises a common reference signal and transmitted data,

determine a first interfering channel matrix for a first interfering cell based on a channel estimation of the common reference signal,

estimate a first power offset ratio and a first effective pre-coding matrix for the first interfering cell by evaluating a maximum likelihood metric, wherein the maximum likelihood metric is based on a first interfering channel correlation,

reconstruct a channel covariance matrix based on the estimated first power offset ratio and the first effective pre-coding matrix, and

detect the transmitted data based on the reconstructed channel covariance matrix.

2. The apparatus of claim 1 , wherein the program instructions, when executed by the processor, further cause the processor to:

evaluate the maximum likelihood metric based on an average covariance matrix.

3. The apparatus of claim 1 , wherein the program instructions, when executed by the processor, further cause the processor to:

generate a triangular matrix using Cholesky factorization of the first interfering channel correlation;

invert the triangular matrix; and

evaluate the maximum likelihood metric based on a spectral decomposition of the inverted triangular matrix and a channel correlation.

4. The apparatus of claim 1 , wherein the program code instructions, when executed by the processor, further cause the processor to:

estimate a set of power offset ratios corresponding to a set of possible effective pre-coding matrices, wherein each power offset ratio in the set of power offset ratios corresponds to one possible effective pre-coding matrix in the set of possible effective pre-coding matrices, and wherein the set of power offset ratios are determined in parallel.

5. The apparatus of claim 4 , wherein the program code instructions, when executed by the processor, further cause the processor to:

evaluate a product of each effective pre-coding matrix and the conjugate transpose of the each effective pre-coding matrix; and

remove an effective pre-coding matrix from the set of effective pre-coding matrices when the corresponding evaluated product is a duplicate of the evaluated product corresponding to another effective pre-coding matrix in the set of effective pre-coding matrices.

6. The apparatus of claim 4 , wherein the program code instructions, when executed by the processor, further cause the processor to:

perform selecting the first power offset ratio from the set of power offset ratios based on the maximum likelihood metric.

7. The apparatus of claim 1 , wherein the program code instructions, when executed by the processor, further cause the processor to:

estimate a second power offset ratio and a second effective pre-coding matrix corresponding to a second interfering cell by:

evaluating a maximum likelihood metric, wherein the maximum likelihood metric is based on the first interfering channel correlation and a second interfering channel correlation, and

reconstructing the channel covariance matrix based on the estimated first power offset ratio, the second power offset ratio, the first effective pre-coding matrix, and the second effective pre-coding matrix.

8. The apparatus of claim 7 , wherein the program code instructions, when executed by the processor, further cause the processor to:

approximate a joint detection of the first power offset ratio and the second power offset ratio by estimating the first power offset ratio based on a maximum likelihood metric, and estimating the second power offset ratio based on a linear relationship between the first power offset ratio and the second power offset ratio.

9. The apparatus of claim 8 , wherein the program code instructions, when executed by the processor, further cause the processor to:

select the first power offset ratio based on the interfering power of the first interfering cell and the interfering power of the second interfering cell, wherein the interfering power of the first interfering cell is greater than the interfering power of the second interfering cell.

10. The apparatus of claim 7 , wherein the program code instructions, when executed by the processor, further cause the processor to:

when the first interfering cell and the second interfering cell have substantially the same interfering power, select as the first interfering cell the interfering cell having better estimation accuracy.

11. The apparatus of claim 1 , wherein the program code instructions, when executed by the processor, further cause the processor to:

detect the transmitted data based on interference rejection combining type receivers.

12. The apparatus of claim 1 , wherein the program code instructions, when executed by the processor, further cause the processor to:

select the first power offset ratio from a set of possible power offset ratios wherein the set of possible power offset ratios includes a zero value.

13. A method for estimating interference in a digital communication signal, wherein the digital communication signal comprises a common reference signal and a transmitted data, the method comprising:

determining a first interfering channel matrix for a first interfering cell based on a channel estimation of the common reference signal;

estimating a first power offset ratio and a first effective pre-coding matrix for the first interfering cell by evaluating a maximum likelihood metric, wherein the maximum likelihood metric is based on a first interfering channel correlation;

reconstructing a channel covariance matrix based on the estimated first power offset ratio and the first effective pre-coding matrix; and

detecting the transmitted data based on the reconstructed channel covariance matrix.

14. The method according to claim 13 , wherein evaluating the maximum likelihood metric comprises:

generating a triangular matrix using Cholesky factorization of the first interfering channel correlation;

inverting the triangular matrix; and

evaluating the maximum likelihood metric based on a spectral decomposition of the inverted triangular matrix and a channel correlation.

15. The method according to claim 13 , wherein evaluating a maximum likelihood metric comprises evaluating the maximum likelihood metric based on an average covariance matrix.

16. A non-transitory memory for storing computer-readable program comprising program code that, when executed by a processor, causes the processor to:

receive a digital communication signal, wherein the digital communication signal comprises a common reference signal and transmitted data;

determine a first interfering channel matrix for a first interfering cell based on a channel estimation of the common reference signal;

estimate a first power offset ratio and a first effective pre-coding matrix for the first interfering cell by evaluating a maximum likelihood metric, wherein the maximum likelihood metric is based on a first interfering channel correlation;

reconstruct a channel covariance matrix based on the estimated first power offset ratio and the first effective pre-coding matrix; and

detect the transmitted data based on the reconstructed channel covariance matrix.

17. The non-transitory memory of claim 16 , wherein the program code, when executed by a processor, further causes the processor to:

evaluate the maximum likelihood metric based on an average covariance matrix.

18. The non-transitory memory of claim 16 , wherein the program code, when executed by a processor, further causes the processor to:

generate a triangular matrix using Cholesky factorization of the first interfering channel correlation;

invert the triangular matrix; and

evaluate the maximum likelihood metric based on a spectral decomposition of the inverted triangular matrix and a channel correlation.

19. The non-transitory memory of claim 16 , wherein the program code, when executed by the processor, further causes the processor to:

detect the transmitted data based on interference rejection combining type receivers.

20. The non-transitory memory of claim 16 , wherein the program code, when executed by the processor, further causes the processor to:

select the first power offset ratio from a set of possible power offset ratios wherein the set of possible power offset ratios includes a zero value.