Adaptive algorithm for a Cholesky approximation

• US 6,690,660 B2
• Filed: 05/22/2002
• Issued: 02/10/2004
• Est. Priority Date: 05/22/2002
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Zeira, Ariela, Kim, Younglok
• Primary Examiner(s): Marcelo, Melvin
• Assistant Examiner(s): DO, NHAT Q
• Application Number:
  US10/153,477
• Publication Number:
  US 20030218998A1
• Time in Patent Office: 629 Days
• Field of Search: 370/335, 370/342, 375/149, 375/150, 375/343, 375/346
• US Class Current: 370/335
• CPC Class Codes: G06F 17/16 Matrix or vector computation , e.g. matrix-matrix or matrix-vector multiplication, matrix factorization matrix transposition G06F7/78
• CPC Class Codes: H04B 1/7105 Joint detection techniques, e.g. linear detectors

Abstract

Data is to be detected in a wireless communication system. A plurality of communication signals are received. A solution for estimating data of the received communication signals is modeled using a linear system requiring a matrix inversion. Columns or rows of an approximate Cholesky factor are determined. A difference between the determined columns or rows is determined. If the determined difference is less than a threshold, subsequent columns or rows are determined by previously determined columns or rows. The data of the received communication signals is estimated using the approximate Cholesky factor.

Claims

1. A method for detecting data in a wireless communication system, the method comprising:

receiving a plurality of communication signals;

modeling a solution for estimating data of the received communication signals using a linear system requiring a matrix inversion;

determining columns or rows of an approximate Cholesky factor;

determining a difference between the determined columns or rows;

if the determined difference is less than a threshold, determining subsequent columns or rows by repeating previously determined columns or rows; and

estimating the data of the received communication signals using the approximate Cholesky factor.

2. The method of claim 1 further comprising repeating previously determined columns or rows, if a number of previously determined columns or rows exceeds an upper limit.

3. The method of claim 1 wherein the linear system is modeled using a minimum mean square error approach.

4. The method of claim 1 wherein the linear system is modeled using a zero forcing approach.

5. The method of claim 1 wherein the approximate Cholesky factor is lower triangular.

6. The method of claim 1 wherein the approximate Cholesky factor comprises a plurality of K by K blocks and K is a number of the received signals.

7. The method of claim 6 wherein the approximate Cholesky factor is determined by columns.

8. The method of claim 7 wherein block columns are L blocks in length and L is the longest length of intersymbol interference.

9. The method of claim 7 wherein block columns are 2L blocks in length and L is the longest length of intersymbol interference.

10. The method of claim 1 wherein the comparison comprises determining an error between normalized blocks of the columns or rows.

11. The method of claim 1 wherein the comparison compares a first determined block of a newly determined column or row to a corresponding block of a previously determined column or row, prior to determining subsequent blocks of the newly determined column or row.

12. A user equipment comprising:

means for receiving a plurality of communication signals;

means for estimating data of the received communication signals using a linear system requiring a matrix inversion;

means for determining columns or rows of an approximate Cholesky factor;

means for determining a difference between the determined columns or rows;

means if the determined difference is less than a threshold, for determining subsequent columns or rows by repeating previously determined columns or rows; and

means for estimating the data of the received communication signals using the approximate Cholesky factor.

13. The user equipment of claim 12 further comprising means for repeating previously determined columns or rows, if a number of previously determined columns or rows exceeds an upper limit.

14. The user equipment of claim 12 wherein the linear system is modeled using a minimum mean square error approach.

15. The user equipment of claim 12 wherein the linear system is modeled using a zero forcing approach.

16. The user equipment of claim 12 wherein the approximate Cholesky factor is lower triangular.

17. The user equipment of claim 12 wherein the approximate Cholesky factor comprises a plurality of K by K blocks and K is a number of the received signals.

18. The user equipment of claim 17 wherein the approximate Cholesky factor is determined by columns.

19. The user equipment of claim 18 wherein block columns are L blocks in length and L is the longest length of intersymbol interference.

20. The user equipment of claim 18 wherein block columns are 2L blocks in length and L is the longest length of intersymbol interference.

21. The user equipment of claim 12 wherein the comparison comprises determining an error between normalized blocks of the columns or rows.

22. The user equipment of claim 12 wherein the comparison compares a first determined block of a newly determined column or row to a corresponding block of a previously determined column or row, prior to determining subsequent blocks of the newly determined column or row.

23. A user equipment comprising:

an antenna for receiving a plurality of communication signals;

a data estimation device for estimating data of the received communication signals using a linear system requiring a matrix inversion;

for determining columns or rows of an approximate Cholesky factor;

for determining a difference between the determined columns or rows;

if the determined difference is less than a threshold, for determining subsequent columns or rows by repeating previously determined columns or rows; and

for estimating the data of the received communication signals using the approximate Cholesky factor.

24. The user equipment of claim 23 wherein the data detection device further for repeating previously determined columns or rows, if a number of previously determined columns or rows exceeds an upper limit.

25. The user equipment of claim 23 wherein the linear system is modeled using a minimum mean square error approach.

26. The user equipment of claim 23 wherein the linear system is modeled using a zero forcing approach.

27. The user equipment of claim 23 wherein the approximate Cholesky factor is lower triangular.

28. The user equipment of claim 23 wherein the approximate Cholesky factor comprises a plurality of K by K blocks and K is a number of the received signals.

29. The user equipment of claim 28 wherein the approximate Cholesky factor is determined by columns.

30. The user equipment of claim 29 wherein block columns are L blocks in length and L is the longest length of intersymbol interference.

31. The user equipment of claim 29 wherein block columns are 2L blocks in length and L is the longest length of intersymbol interference.

32. The user equipment of claim 23 wherein the comparison comprises determining an error between normalized blocks of the columns or rows.

33. The user equipment of claim 23 wherein the comparison compares a first determined block of a newly determined column or row to a corresponding block of a previously determined column or row, prior to determining subsequent blocks of the newly determined column or row.

34. A base station comprising:

means for receiving a plurality of communication signals;

means for estimating data of the received communication signals using a linear system requiring a matrix inversion;

means for determining columns or rows of an approximate Cholesky factor;

means for determining a difference between the determined columns or rows;

means if the determined difference is less than a threshold, for determining subsequent columns or rows by repeating previously determined columns or rows; and

means for estimating the data of the received communication signals using the approximate Cholesky factor.

35. The base station of claim 34 further comprising means for repeating previously determined columns or rows, if a number of previously determined columns or rows exceeds an upper limit.

36. The base station of claim 34 wherein the linear system is modeled using a minimum mean square error approach.

37. The base station of claim 34 wherein the linear system is modeled using a zero forcing approach.

38. The base station of claim 34 wherein the approximate Cholesky factor is lower triangular.

39. The base station of claim 34 wherein the approximate Cholesky factor comprises a plurality of K by K blocks and K is a number of the received signals.

40. The base station of claim 39 wherein the approximate Cholesky factor is determined by columns.

41. The base station of claim 40 wherein block columns are L blocks in length and L is the longest length of intersymbol interference.

42. The base station of claim 40 wherein block columns are 2L blocks in length and L is the longest length of intersymbol interference.

43. The base station of claim 34 wherein the comparison comprises determining an error between normalized blocks of the columns or rows.

44. The base station of claim 34 wherein the comparison compares a first determined block of a newly determined column or row to a corresponding block of a previously determined column or row, prior to determining subsequent blocks of the newly determined column or row.

45. A base station comprising:

an antenna for receiving a plurality of communication signals;

a data estimation device for estimating data of the received communication signals using a linear system requiring a matrix inversion;

for determining columns or rows of an approximate Cholesky factor;

for determining a difference between the determined columns or rows;

if the determined difference is less than a threshold, for determining subsequent columns or rows by repeating previously determined columns or rows; and

for estimating the data of the received communication signals using the approximate Cholesky factor.

46. The base station of claim 45 wherein the data detection device further for repeating previously determined columns or rows, if a number of previously determined columns or rows exceeds an upper limit.

47. The base station of claim 45 wherein the linear system is modeled using a minimum mean square error approach.

48. The base station of claim 45 wherein the linear system is modeled using a zero forcing approach.

49. The base station of claim 45 wherein the approximate Cholesky factor is lower triangular.

50. The base station of claim 45 wherein the approximate Cholesky factor comprises a plurality of K by K blocks and K is a number of the received signals.

51. The base station of claim 50 wherein the approximate Cholesky factor is determined by columns.

52. The base station of claim 51 wherein block columns are L blocks in length and L is the longest length of intersymbol interference.

53. The base station of claim 51 wherein block columns are 2L blocks in length and L is the longest length of intersymbol interference.

54. The base station of claim 45 wherein the comparison comprises determining an error between normalized blocks of the columns or rows.

55. The base station of claim 45 wherein the comparison compares a first determined block of a newly determined column or row to a corresponding block of a previously determined column or row, prior to determining subsequent blocks of the newly determined column or row.