Multiple signal transformation in wireless receivers

• US 8,655,282 B2
• Filed: 10/24/2011
• Issued: 02/18/2014
• Est. Priority Date: 10/29/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Luo, Xiliang, Yoo, Taesang, Luo, Tao
• Primary Examiner(s): Nguyen, Hai V
• Application Number:
  US13/280,142
• Publication Number:
  US 20120108175A1
• Time in Patent Office: 848 Days
• Field of Search: 455/63.1
• US Class Current: 455/63.1
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2691 involving interference determination or cancellation
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT

Abstract

A frontend receiver of a user equipment (UE) is configured with multiple transform operations assigned to separate sets of cells. One set of cells includes the serving cell of the UE and at least one additional cell within a first offset range of the serving cell. Another set or sets of cells include additional interferer cells within another offset range of the serving cell. After tracking the common frequency/timing offsets of each set of cells the assigned transform operation for that set transforms the time domain samples into frequency domain symbols. The individual frequency/timing offsets for each cell within the set are then tracked.

Claims

1. A method of wireless communication at a user equipment (UE), comprising:

tracking a first common offset corresponding to a first group of cells, said first group of cells comprising a serving cell and at least one cell having an offset within a first range of said serving cell;

transforming a plurality of time domain samples into a first plurality of frequency domain symbols using said offset and a first transformation operation assigned to said first group of cells;

tracking a first individual offset of said first plurality of frequency domain symbols for each cell within said first group of cells;

tracking a second common offset corresponding to a second group of cells, said second group of cells comprising at least one cell having an offset within a second range of said serving cell;

transforming said plurality of time domain samples into a second plurality of frequency domain symbols using said second offset and a second transformation operation assigned to said second group of cells; and

tracking a second individual offset of said second plurality of frequency domain symbols for each cell within said second group of cells.

2. The method of claim 1 further comprising:

tracking a third common offset corresponding to a third group of cells, said third group of cells comprising at least one cell having an offset within a third range of said serving cell;

transforming said plurality of time domain samples into a third plurality of frequency domain symbols using said third offset and a third transformation operation assigned to said third group of cells;

tracking a third individual offset of said third plurality of frequency domain symbols for each cell within said third group of cells.

3. The method of claim 1 wherein said first and second offsets are timing offsets.

4. The method of claim 1 wherein said first and second offsets are frequency offsets.

5. The method of claim 1 further comprising:

processing said first and second pluralities of frequency domain symbols.

6. The method of claim 5 wherein said processing comprises one or more of:

estimating a channel of said first and second pluralities of frequency domain symbols;

demodulating said first and second pluralities of frequency domain symbols; and

decoding said first and second pluralities of frequency domain symbols.

7. The method of claim 1 further comprising:

adjusting said plurality of time domain samples according to said tracked first common offset;

adjusting said plurality of time domain samples according to said tracked second common offset;

for each of said cells in said first group of cells, adjusting said first plurality of frequency domain symbols according to said tracked first individual offset; and

for each of said cells in said second group of cells, adjusting said second plurality of frequency domain symbols according to said tracked second individual offset.

8. The method of claim 1 further comprising:

applying interference cancellation among a first transformation cluster, said first transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said first group of cells; and

applying interference cancellation among a second transformation cluster, said second transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said second group of cells.

9. The method of claim 8 further comprising:

determining a cancellation order of said first and second transformation clusters.

10. The method of claim 8 further comprising:

applying time domain interference cancellation for a subset of clusters, said subset of clusters comprising a subset of;

at least one signal from one or more of said plurality of time domain samples and said first plurality of frequency domain symbols of said first transformation cluster; and

at least one signal from one or more of said plurality of time domain samples and said second plurality of frequency domain symbols of said second transformation cluster.

11. The method of claim 8 further comprising:

applying frequency domain interference cancellation for a subset of clusters, said subset of clusters comprising a subset of;

at least one signal from one or more of said plurality of time domain samples and said first plurality of frequency domain symbols of said first transformation cluster; and

at least one signal from one or more of said plurality of time domain samples and said second plurality of frequency domain symbols of said second transformation cluster.

12. The method of claim 8 wherein a total number of transformation clusters is determined by one or more of:

a relative timing/frequency offset of a plurality of cells within range of said UE;

a relative signal strength of said plurality of cells;

a location of said serving cell.

13. The method of claim 12 wherein said total number of transformation clusters is adjusted dynamically across different subframes.

14. The method of claim 8 further comprising:

applying interference cancellation iteratively between each of said first transformation cluster and said second transformation cluster.

15. The method of claim 14 wherein one of said first transformation cluster and said second transformation cluster uses time domain interference cancellation.

16. The method of claim 15 wherein another of said first transformation cluster and said second transformation cluster uses frequency domain interference cancellation after use of said time domain interference cancellation.

44. The UE of claim 8 wherein said at least one processor is further configured:

to apply interference cancellation iteratively between each of said first transformation cluster and said second transformation cluster.

45. The UE of claim 44 wherein one of said first transformation cluster and said second transformation cluster uses time domain interference cancellation.

46. The UE of claim 45 wherein another of said first transformation cluster and said second transformation cluster uses frequency domain interference cancellation after use of said time domain interference cancellation.

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

means for tracking a first common offset corresponding to a first group of cells, said first group of cells comprising a serving cell and at least one cell having an offset within a first range of said serving cell;

means for transforming a plurality of time domain samples into a first plurality of frequency domain symbols using said offset and a first transformation operation assigned to said first group of cells;

means for tracking a first individual offset of said first plurality of frequency domain symbols for each cell within said first group of cells;

means for tracking a second common offset corresponding to a second group of cells, said second group of cells comprising at least one cell having an offset within a second range of said serving cell;

means for transforming said plurality of time domain samples into a second plurality of frequency domain symbols using said second offset and a second transformation operation assigned to said second group of cells; and

means for tracking a second individual offset of said second plurality of frequency domain symbols for each cell within said second group of cells.

18. The UE of claim 17 further comprising:

means for tracking a third common offset corresponding to a third group of cells, said third group of cells comprising at least one cell having an offset within a third range of said serving cell;

means for transforming said plurality of time domain samples into a third plurality of frequency domain symbols using said third offset and a third transformation operation assigned to said third group of cells;

means for tracking a third individual offset of said third plurality of frequency domain symbols for each cell within said third group of cells.

19. The UE of claim 17 wherein said first and second offsets are timing offsets.

20. The UE of claim 17 wherein said first and second offsets are frequency offsets.

21. The UE of claim 17 further comprising:

means for processing said first and second pluralities of frequency domain symbols.

22. The UE of claim 17 further comprising:

means for adjusting said plurality of time domain samples according to said tracked first common offset;

means for adjusting said plurality of time domain samples according to said tracked second common offset;

for each of said cells in said first group of cells, means for adjusting said first plurality of frequency domain symbols according to said tracked first individual offset; and

for each of said cells in said second group of cells, means for adjusting said second plurality of frequency domain symbols according to said tracked second individual offset.

23. The UE of claim 17 further comprising:

means for applying interference cancellation among a first transformation cluster, said first transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said first group of cells; and

means for applying interference cancellation among a second transformation cluster, said second transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said second group of cells.

24. A computer program product for wireless communications by a user equipment (UE) in a wireless network, comprising:

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

program code to track a first common offset corresponding to a first group of cells, said first group of cells comprising a serving cell and at least one cell having an offset within a first range of said serving cell;

program code to transform a plurality of time domain samples into a first plurality of frequency domain symbols using said offset and a first transformation operation assigned to said first group of cells;

program code to track a first individual offset of said first plurality of frequency domain symbols for each cell within said first group of cells;

program code to track a second common offset corresponding to a second group of cells, said second group of cells comprising at least one cell having an offset within a second range of said serving cell;

program code to transform said plurality of time domain samples into a second plurality of frequency domain symbols using said second offset and a second transformation operation assigned to said second group of cells; and

program code to track a second individual offset of said second plurality of frequency domain symbols for each cell within said second group of cells.

25. The computer program product of claim 24 further comprising:

program code to track a third common offset corresponding to a third group of cells, said third group of cells comprising at least one cell having an offset within a third range of said serving cell;

program code to transform said plurality of time domain samples into a third plurality of frequency domain symbols using said third offset and a third transformation operation assigned to said third group of cells;

program code to track a third individual offset of said third plurality of frequency domain symbols for each cell within said third group of cells.

26. The computer program product of claim 24 wherein said first and second offsets are timing offsets.

27. The computer program product of claim 24 wherein said first and second offsets are frequency offsets.

28. The computer program product of claim 24 further comprising:

program code to process said first and second pluralities of frequency domain symbols.

29. The computer program product of claim 24 further comprising:

program code to adjust said plurality of time domain samples according to said tracked first common offset;

program code to adjust said plurality of time domain samples according to said tracked second common offset;

program code, executable for each of said cells in said first group of cells, to adjust said first plurality of frequency domain symbols according to said tracked first individual offset; and

program code, executable for each of said cells in said second group of cells, to adjust said second plurality of frequency domain symbols according to said tracked second individual offset.

30. The computer program product of claim 24 further comprising:

program code to apply interference cancellation among a first transformation cluster, said first transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said first group of cells; and

program code to apply interference cancellation among a second transformation cluster, said second transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said second group of cells.

31. 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 track a first common offset corresponding to a first group of cells, said first group of cells comprising a serving cell and at least one cell having an offset within a first range of said serving cell;

to transform a plurality of time domain samples into a first plurality of frequency domain symbols using said offset and a first transformation operation assigned to said first group of cells;

to track a first individual offset of said first plurality of frequency domain symbols for each cell within said first group of cells;

to track a second common offset corresponding to a second group of cells, said second group of cells comprising at least one cell having an offset within a second range of said serving cell;

to transform said plurality of time domain samples into a second plurality of frequency domain symbols using said second offset and a second transformation operation assigned to said second group of cells; and

to track a second individual offset of said second plurality of frequency domain symbols for each cell within said second group of cells.

32. The UE of claim 31 wherein said at least one processor is further configured:

to track a third common offset corresponding to a third group of cells, said third group of cells comprising at least one cell having an offset within a third range of said serving cell;

to transform said plurality of time domain samples into a third plurality of frequency domain symbols using said third offset and a third transformation operation assigned to said third group of cells;

to track a third individual offset of said third plurality of frequency domain symbols for each cell within said third group of cells.

33. The UE of claim 31 wherein said first and second offsets are timing offsets.

34. The UE of claim 31 wherein said first and second offsets are frequency offsets.

35. The UE of claim 31 wherein said at least one processor is further configured:

to process said first and second pluralities of frequency domain symbols.

36. The UE of claim 35 wherein said processing comprises one or more of:

to estimate a channel of said first and second pluralities of frequency domain symbols;

to demodulate said first and second pluralities of frequency domain symbols; and

to decode said first and second pluralities of frequency domain symbols.

37. The UE of claim 31 wherein said at least one processor is further configured:

to adjust said plurality of time domain samples according to said tracked first common offset;

to adjust said plurality of time domain samples according to said tracked second common offset;

for each of said cells in said first group of cells, to adjust said first plurality of frequency domain symbols according to said tracked first individual offset; and

for each of said cells in said second group of cells, to adjust said second plurality of frequency domain symbols according to said tracked second individual offset.

38. The UE of claim 31 wherein said at least one processor is further configured:

to apply interference cancellation among a first transformation cluster, said first transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said first group of cells; and

to apply interference cancellation among a second transformation cluster, said second transformation cluster comprising said plurality of time domain samples and said first plurality of frequency domain symbols of said second group of cells.

39. The UE of claim 38 wherein said at least one processor is further configured:

to determine a cancellation order of said first and second transformation clusters.

40. The UE of claim 38 wherein said at least one processor is further configured:

to apply time domain interference cancellation for a subset of clusters, said subset of clusters comprising a subset of;

at least one signal from one or more of said plurality of time domain samples and said first plurality of frequency domain symbols of said first transformation cluster; and

at least one signal from one or more of said plurality of time domain samples and said second plurality of frequency domain symbols of said second transformation cluster.

41. The UE of claim 38 wherein said at least one processor is further configured:

to apply frequency domain interference cancellation for a subset of clusters, said subset of clusters comprising a subset of;

at least one signal from one or more of said plurality of time domain samples and said first plurality of frequency domain symbols of said first transformation cluster; and

at least one signal from one or more of said plurality of time domain samples and said second plurality of frequency domain symbols of said second transformation cluster.

42. The UE of claim 38 wherein a total number of transformation clusters is determined by one or more of:

a relative timing/frequency offset of a plurality of cells within range of said UE;

a relative signal strength of said plurality of cells;

a location of said serving cell.

43. The UE of claim 42 wherein said total number of transformation clusters is adjusted dynamically across different subframes.