Channel estimation for reference signal interference cancelation

• US 9,503,285 B2
• Filed: 08/01/2011
• Issued: 11/22/2016
• Est. Priority Date: 03/01/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yoo, Taesang, Luo, Tao
• Primary Examiner(s): WONG, XAVIER S
• Application Number:
  US13/195,711
• Publication Number:
  US 20120224499A1
• Time in Patent Office: 1,940 Days
• US Class Current: 1/1
• CPC Class Codes: H04J 11/005 of intercell interference
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04W 52/02 Power saving arrangements in wired systems H04L12/12; signaling of mobile application services, e.g. low battery notifications H04W4/20
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Various aspects disclosed are directed to improvements to channel estimation through more efficient cancelation of neighboring common reference signals (CRS). Cancelation of CRS from other cells allows the user equipment (UE) a better opportunity for accurately detecting the reference signal of the current cell. Alternative aspects have a recursive element that uses previous estimates as the basis for the current channel estimate. The various aspects of the present disclosure generally have two alternative embodiments: (1) initializing the channel estimation for all cells with a previous channel estimate and cancellation of reference signals of non-target cells to accurately update channel estimate of the target cell; and (2) initializing the channel estimate for all cells with a previous channel estimate and cancelation of reference signals of all cells to accurately estimate residual channel estimate of the target cell and update its channel estimate.

Claims

1. A method of wireless communication, comprising:

calculating a correlation between a current subframe and a previous subframe;

modifying a previous channel estimate computed for the previous subframe according to said correlation;

initializing a current channel estimate using the previous channel estimate;

selecting a target cell from a plurality of cells;

canceling interfering signals of non-target cells of said plurality of cells from a received signal in said target cell, said canceling resulting in a remaining signal;

filtering said remaining signal using a channel estimator; and

updating said current channel estimate of said target cell using said filtered remaining signal.

2. The method of claim 1 further comprising:

selecting a next target cell from said plurality of cells;

performing said canceling, said filtering, and said updating for said next target cell.

3. The method of claim 1 wherein said channel estimator comprises a single cell channel estimator.

4. The method of claim 1 wherein said canceling, said filtering, and said updating are performed over a plurality of iterations.

5. A method of wireless communication, comprising:

calculating a correlation between a current subframe and a previous subframe;

modifying a previous channel estimate computed for the previous subframe according to said correlation;

initializing a current channel estimate using the previous channel estimate;

canceling interfering signals of a target cell and non-target cells from a received signal, said canceling resulting in a residual signal;

filtering said residual signal using a channel estimator; and

updating said current channel estimate of said target cell using said filtered residual signal and said previous channel estimate.

6. The method of claim 5 wherein said canceling is performed on said interfering signals originating from one of:

said target cell; and

a plurality of cells.

7. The method of claim 6, said interfering signals originating from said plurality of cells, wherein said canceling, said filtering, and said updating are performed for said target cell and each cell of said plurality of cells.

8. The method of claim 7 wherein said canceling, said filtering, and said updating for said target cell and each cell of said plurality of cells are performed over a plurality of iterations.

9. The method of claim 5 wherein said channel estimator comprises a single cell channel estimator.

10. A user equipment (UE) configured for wireless communication, comprising:

means for calculating a correlation between a current subframe and a previous subframe;

means for modifying a previous channel estimate computed for the previous subframe according to said correlation;

means for initializing a current channel estimate using previous channel estimate;

means for selecting a target cell from a plurality of cells;

means for canceling interfering signals of non-target cells of said plurality of cells from a received signal in said target cell, said means for canceling resulting in a remaining signal;

means for filtering said remaining signal using a channel estimator; and

means for updating said current channel estimate of said target cell using said filtered remaining signal.

11. The UE of claim 10 further comprising:

means for selecting a next target cell from said plurality of cells;

means for performing said means for canceling, said means for filtering, and said means for updating for said next target cell.

12. The UE of claim 10 wherein said channel estimator comprises a single cell channel estimator.

13. The UE of claim 10 wherein said means for canceling, said means for filtering, and said means for updating are performed over a plurality of iterations.

14. A user equipment (UE) configured for wireless communication, comprising:

means for calculating a correlation between a current subframe and a previous subframe;

means for modifying a previous channel estimate computed for the previous subframe according to said correlation;

means for initializing a current channel estimate using the previous channel estimate;

means for canceling interfering signals of a target cell and non-target cells from a received signal, said means for canceling resulting in a residual signal;

means for filtering said residual signal using a channel estimator; and

means for updating said current channel estimate of said target cell using said filtered residual signal and said previous channel estimate.

15. The UE of claim 14 wherein said means for canceling is performed on said interfering signals originating from one of:

said target cell; and

a plurality of cells.

16. The UE of claim 15, said interfering signals originating from one of said target cell and said plurality of cells, wherein said means for canceling, said means for filtering, and said means for updating are performed for said target cell and each cell of said plurality of cells.

17. The UE of claim 16 wherein said means for canceling, said means for filtering, and said means for updating said target cell and each cell of said plurality of cells are performed over a plurality of iterations.

18. The UE of claim 14 wherein said channel estimator comprises a single cell channel estimator.

19. A computer program product for wireless communications in a wireless network, comprising:

a non-transitory computer-readable medium having program code recorded thereon, said program code comprising;

program code to calculate a correlation between a current subframe and a previous subframe;

program code to modify a previous channel estimate computed for the previous subframe according to said correlation;

program code to initialize a current channel estimate using the previous channel estimate;

program code to select a target cell from a plurality of cells;

program code to cancel interfering signals of non-target cells of said plurality of cells from a received signal in said target cell, execution of said program code to cancel resulting in a remaining signal;

program code to filter said remaining signal using a channel estimator; and

program code to update said current channel estimate of said target cell using said filtered remaining signal.

20. The computer program product of claim 19 further comprising:

program code to select a next target cell from said plurality of cells;

program code to execute said program code to cancel, said program code to filter, and said program code to update for said next target cell.

21. The computer program product of claim 19 wherein said channel estimator comprises a single cell channel estimator.

22. The computer program product of claim 19 wherein said program code to cancel, said program code to filter, and said program code to update are performed over a plurality of iterations.

23. A computer program product for wireless communications in a wireless network, comprising:

a non-transitory computer-readable medium having program code recorded thereon, said program code comprising;

program code to calculate a correlation between a current subframe and a previous subframe;

program code to modify a previous channel estimate computed for the previous subframe according to said correlation;

program code to initialize a current channel estimate using the previous channel;

program code to cancel interfering signals of a target cell and non-target cells from a received signal, said program code to cancel resulting in a residual signal;

program code to filter said residual signal using a channel estimator; and

program code to update said current channel estimate of said target cell using said filtered residual signal and said previous channel estimate.

24. The computer program product of claim 23 wherein said program code to cancel is performed on said interfering signals originating from one of:

said target cell; and

a plurality of cells.

25. The computer program product of claim 24, said interfering signals originating from one of said target cell and said plurality of cells, wherein said program code to cancel, said program code to filter, and said program code to update are performed for said target cell and each cell of said plurality of cells.

26. The computer program product of claim 25 wherein said program code to cancel, said program code to filter, and said program code to update for said target cell and each cell of said plurality of cells are performed over a plurality of iterations.

27. The computer program product of claim 23 wherein said channel estimator comprises a single cell channel estimator.

28. A user equipment (UE) configured for wireless communication, said UE comprising:

at least one processor; and

a memory coupled to said at least one processor,

wherein said at least one processor is configured to;

calculate a correlation between a current subframe and a previous subframe;

modify a previous channel estimate computed for the previous subframe according to said correlation;

initialize a current channel estimate using the previous channel estimate;

select a target cell from a plurality of cells;

cancel interfering signals of non-target cells of said plurality of cells from a received signal in said target cell, said cancelation resulting in a remaining signal;

filter said remaining signal using a channel estimator; and

update said current channel estimate of said target cell using said filtered remaining signal.

29. The UE of claim 28 said at least one processor further configured to:

select a next target cell from said plurality of cells;

perform said cancelation, said filtering, and said update for said next target cell.

30. The UE of claim 28 wherein said channel estimator comprises a single cell channel estimator.

31. The UE of claim 28 wherein said configuration of said at least one processor to cancel, to filter, and s to update are performed over a plurality of iterations.

32. A user equipment (UE) configured for wireless communication, said UE comprising:

at least one processor; and

a memory coupled to said at least one processor,

wherein said at least one processor is configured to;

calculate a correlation between a current subframe and a previous subframe,

modify a previous channel estimate computed for the previous subframe according to said correlation;

initialize a current channel estimate using the previous channel estimate;

cancel interfering signals of a target cell and non-target cells from a received signal, said cancelation resulting in a residual signal;

filter said residual signal using a channel estimator; and

update said current channel estimate of said target cell using said filtered residual signal and said previous channel estimate.

33. The UE of claim 32 wherein said configuration of said at least one processor to cancel is performed on said interfering signals originating from one of:

said target cell; and

a plurality of cells.

34. The UE of claim 33, said interfering signals originating from said target cell and said plurality of cells, wherein said configuration of said at least one processor to cancel, to filter, and to update are performed for said target cell and each cell of said plurality of cells.

35. The UE of claim 34 wherein said configuration of said at least one processor to cancel, to filter, and to update for said target cell and each cell of said plurality of cells are performed over a plurality of iterations.

36. The UE of claim 32 wherein said channel estimator comprises a single cell channel estimator.