Tone hopping methods and apparatus

• US 20090122810A9
• Filed: 12/22/2005
• Published: 05/14/2009
• Est. Priority Date: 10/14/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Li, Junyi, Jin, Hui
• Granted Patent: US 7,715,845 B2
• Time in Patent Office: Days
• US Class Current: 370/468
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

Methods and apparatus for allocating and hopping tones for uplink communications purposes in adjacent sectors and neighboring cells of an OFDM system are described. Physical tones used in each sector and cell are allocated to tone hopping sequences according to a tone to tone hopping sequence allocation function which uses both a cell identifier and sector identifier. Different sectors and cells use different tone to tone hopping sequence allocation functions through the use of different cell and/or sector identifiers to minimize the number of collisions between hopping sequences of adjacent sectors and neighboring cells. Uplink tone hopping sequences, corresponding to logical tones are allocated to uplink communications channels. Uplink communications channels are used by wireless terminals, e.g., mobile nodes, to transmit data to base stations. Over time, a wireless terminal uses the tones included in the uplink tone hopping sequences corresponding to uplink communications channels it is authorized to use.

Claims

1. A method of implementing tone hopping in a frequency division multiplexed system, said system including at least one cell including multiple sectors, the method comprising the steps of:

determining a plurality of physical tone indexes, said physical indexes corresponding to physical tones to be used to transmit signals based on a tone hopping function which uses a cell identifier and a sector identifier to control the mapping of logical tones to physical tones as a function of time; and

transmitting signals using said physical tones corresponding to the determined physical tone indexes.

2. The method of claim 1, wherein said tones are orthogonal frequency division multiplexing (OFDM) tones.

3. The method of claim 2, wherein said determining step is preformed once per dwell, each dwell including a fixed number of consecutive orthogonal frequency division multiplexing (OFDM) time periods.

4. The method of claim 1, wherein determining the plurality of physical tone indexes as a function of time includes using a quadratic time dependent parameter.

5. The method of claim 4, wherein determining the plurality of physical tone indexes as a function of time further includes using a linear time dependent parameter in addition to said quadratic time dependent parameter.

6. The method of claim 5, wherein at least one of said cell and sector identifiers are used to scale at least one of the linear time dependent parameter and said quadratic time dependent parameter.

7. The method of claim 6, wherein said cell and sector identifiers are used in combination to scale one of said linear time dependent parameter and said quadratic time dependent parameter;

and

wherein a single one of said cell and sector identifiers are used to scale the one of said linear time dependent parameter and said quadratic time dependent parameter which is not scaled using said combination of cell and sector identifiers.

8. The method of claim 7, wherein said cell and sector identifiers are integer values.

9. The method of claim 8, wherein said cell identifier is a value from a set of predetermined cell identifier values.

10. The method of claim 9, wherein said sector identifier is a value from a set of predetermined sector type identifier values.

11. The method of claim 3, wherein said tone hopping function is a periodic function having a predetermined period which is independent of both the sector type identifier and cell identifier.

12. The method of claim 11, the method further comprising resetting said linear time dependent parameter on a periodic basis.

13. The method of claim 12, wherein said resetting is performed through the use of at least one modular computation operation.

14. The method of claim 12, wherein said linear time dependent parameter has a different value for each dwell that occurs between a reset.

15. The method of claim 11, where the sector type identifier is different for adjacent sectors of a cell.

16. The method of claim 15, wherein the cell identifier is different for adjacent cells.

17. The method of claim 13, wherein the periodicity of the hopping function is longer than the interval between resets of the linear time dependent parameter.

18. The method of claim 12, wherein the periodicity of the hopping function is longer than the interval between resets of the linear time dependent parameter;

and

wherein for any two sectors of the same cell having different sector types and the same cell identifier, said two sectors including a first sector and a second sector, which each use the same set of logical tone indexes, in the first sector for a first logical tone index and in the second sector for a second logical tone index, during the interval between said occurrence of said resets, with respect to the first sector the first logical tone index will be mapped to a first corresponding physical tone on a dwell by dwell basis and with respect to the second sector the second logical tone index will be mapped to a second corresponding physical tone on a dwell by dwell basis, and wherein there is at most a single dwell between said time resets wherein the first and second logical tones will be mapped to correspond to the same physical tone.

19. The method of claim 18, wherein the first logical tone index is any tone index from the set of logical tone indexes and wherein the second logical tone index is any tone index from the set of logical tone indexes.

20. The method of claim 12, wherein the periodicity of the hopping function is longer than the interval between resets of the linear time dependent parameter;

and

wherein for any two sectors corresponding to different cells, said different cells having different cell identifiers, said two sectors including a first sector and a second sector which each use the same set of logical tone indexes, in the first sector for a first logical tone index and in the second sector for a second logical tone index, during the interval between said occurrence of said resets, with respect to the first sector the first logical tone index will be mapped to a first corresponding physical tone on a dwell by dwell basis and with respect to the second sector the second logical tone will be mapped to a second corresponding physical tone on a dwell by dwell basis, and wherein there is at most at most two dwells between said time resets wherein the first and second logical tones will be mapped to correspond to the same physical tone.

21. The method of claim 20, wherein the first logical tone index is any tone index from the set of logical tone indexes and wherein the second logical tone index is any tone index from the set of logical tone indexes.

22. The method of claim 3, wherein said hopping function can be expressed in the form of the equation:

f_s^T(j,k)=s/((1/j)+T*k+k²),

where the operations in the equation are in GF(z) where;

j is the logical tone index,

T is the sector type identifier,

s is the cell identifier,

k is the linear time dependent parameter,

k² is the quadratic time dependent parameter,

f_s^T is a hopping function used in a sector with sector type identifier T and cell identifier s,

f_s^T(j,k) is the physical tone index corresponding to logical tone j used during dwell k in a sector with sector type identifier T and cell identifier s,

z is the number of logical indexed tones and the number of physical indexed tones, and

wherein j, s, k, k², f_s^T(j,k), z are non-negative integers.

23. The method of claim 22, wherein z is 113, T is a value in the set of {0, 1, 2}, s is an integer value in a set of at least 5 different integers, k is an integer greater than or equal to 0 and less than or equal to 59.

24. The method of claim 22, wherein k=(L mod 4)*15+floor function ((t−

9)/7), where

L is a superslot index within a beaconslot and L is an integer in the range 0 to 7,

t is a symbol index of a superslot having an index range of 0 to 113 and t is an integer in the range 9 to 113.

25. The method of claim 3, wherein said steps of determining and transmitting are performed by a first wireless terminal.

26. The method of claim 25 further comprising:

operating the first wireless terminal to receive assignment information indicating a set of logical tone indexes assigned to said first wireless terminal, said first wireless terminal using physical tones determined to correspond to the assigned logical tones.

27. The method of claim 25 further comprising:

operating a second wireless in the same cell as said first wireless terminal to perform the steps of;

determining a plurality of physical tone indexes, said physical indexes corresponding to physical tones to be used to transmit signals based on a tone hopping function which uses a cell identifier and a sector identifier to control the mapping of logical tones to physical tones as a function of time;

transmitting signals using said physical tones corresponding to the determined physical tone indexes; and

wherein each of said first and second wireless terminal use the same sector type identifier, cell identifier and time values but use different disjoint sets of logical tones on which to transmit signals.

28. The method of claim 25 further comprising:

operating the second wireless terminal to receive assignment information indicating a set of logical tone indexes assigned to said second wireless terminal, said second wireless terminal using physical tones determined to correspond to the assigned logical tones.

29. The method of claim 3, further comprising:

determining said cell identifier from downlink signals received from a base station.

30. The method of claim 29, wherein determining said cell identifier includes determining the cell identifier from a pattern of high power signals received from said base station.

31. The method of claim 30, wherein said high power signals are pilot signals, beacon signals or a combination of pilot and beacon signals.

32. The method of claim 3, further comprising:

determining said sector type identifier from downlink signals received from a base station.

33. The method of claim 32, wherein determining said sector identifier includes determining the type identifier from a pattern of high power signals received from said base station.

34. The method of claim 33, wherein said high power signals are pilot signals, beacon signals or a combination of pilot and beacon signals.

35. The method of claim 3, wherein said method is implemented by a base station.

36. A wireless terminal for use in a frequency division multiplexed communications system including a multi-sector cell, the wireless terminal comprising:

a tone hopping module for determining a plurality of physical tone indexes, said physical indexes corresponding to physical tones to be used to transmit signals based on a tone hopping function which uses a cell identifier and a sector identifier to control the mapping of logical tones to physical tones as a function of time; and

a transmitter for transmitting signals on physical tones corresponding to the determined physical tone indexes.

37. The wireless terminal of claim 36, wherein said tones are orthogonal frequency division multiplexing (OFDM) tones.

38. The wireless terminal of claim 37, wherein said determining step is preformed once per dwell, each dwell including a fixed number of consecutive orthogonal frequency division multiplexing (OFDM) time periods.

39. The wireless terminal of claim 36, wherein said tone hopping module has a timing input for receiving a timing value used in generating a quadratic time dependent parameter used in determining the plurality of physical tone indexes as a function of time.

40. The wireless terminal of claim 39, wherein said tone hopping module further includes:

means for using a linear time dependent parameter, which is a function of said timing value, in addition to said quadratic time dependent parameter, when determining the plurality of physical tone indexes as a function of time.

41. The wireless terminal of claim 40, wherein tone hopping module includes a sector identifier and a cell identifier input and wherein said tone hopping module uses at least one of said cell and sector identifiers to scale at least one of the linear time dependent parameter and said quadratic time dependent parameter.

42. The wireless terminal of claim 41, wherein said cell and sector identifiers are used in combination to scale one of said linear time dependent parameter and said quadratic time dependent parameter;

and

wherein a single one of said cell and sector identifiers are used to scale the one of said linear time dependent parameter and said quadratic time dependent parameter which is not scaled using said combination of cell and sector identifiers.

43. The wireless terminal of claim 42, wherein said cell and sector identifiers are integer values.

44. The wireless terminal of claim 43, wherein said cell identifier is a value from a set of predetermined cell identifier values.

45. The wireless terminal of claim 44, wherein said sector identifier is a value from a set of predetermined sector type identifier values.

46. The wireless terminal of claim 38, wherein said tone hopping function is a periodic function having a predetermined period which is independent of both the sector type identifier and cell identifier.

47. The wireless terminal of claim 46, further comprising:

means for modular computation operations.

48. The method of claim 45, where the sector type identifier is different for adjacent sectors of a cell.

49. The wireless terminal of claim 48, wherein the cell identifier is different for adjacent cells.

50. The wireless terminal of claim 46, wherein the linear time dependent parameter is reset on a periodic basis.

51. The wireless terminal of claim 50, wherein the linear time dependent parameter has a different value for each dwell that occurs between a reset.

52. The wireless terminal of claim 50, wherein the periodicity of the hopping function is longer than the interval between resets of the linear time dependent parameter.

53. The wireless terminal of claim 51, wherein the periodicity of the hopping function is longer than the interval between resets of the linear time dependent parameter;

and

wherein for any two sectors of the same cell having different sector types and the same cell identifier, said two sectors including a first sector and a second sector, which each use the same set of logical tone indexes, in the first sector for a first logical tone index and in the second sector for a second logical tone index, during the interval between said occurrence of said resets, with respect to the first sector the first logical tone index will be mapped to a first corresponding physical tone on a dwell by dwell basis and with respect to the second sector the second logical tone index will be mapped to a second corresponding physical tone on a dwell by dwell basis, and wherein there is at most a single dwell between said time resets wherein the first and second logical tones will be mapped to correspond to the same physical tone.

54. The wireless terminal of claim 51, wherein the periodicity of the hopping function is longer than the interval between resets of the linear time dependent parameter;

and

wherein for any two sectors corresponding to different cells, said different cells having different cell identifiers, said two sectors including a first sector and a second sector which each use the same set of logical tone indexes, in the first sector for a first logical tone index and in the second sector for a second logical tone index, during the interval between said occurrence of said resets, with respect to the first sector the first logical tone index will be mapped to a first corresponding physical tone on a dwell by dwell basis and with respect to the second sector the second logical tone will be mapped to a second corresponding physical tone on a dwell by dwell basis, and wherein there is at most at most two dwells between said time resets wherein the first and second logical tones will be mapped to correspond to the same physical tone.

55. The wireless terminal of claim 38, wherein said hopping function can be expressed in the form of the equation

f_s^T(j,k)=s/((1/j)+T*k+k²),

where the operations in the equation are in GF(z) where:

j is the logical tone index,

T is the sector type identifier,

s is the cell identifier,

k is the linear time dependent parameter,

k² is the quadratic time dependent parameter,

f_s^T is a hopping function used in a sector with sector type identifier T and cell identifier s,

f_s^T(j,k) is the physical tone index corresponding to logical tone j used during dwell k in a sector with sector type identifier T and cell identifier s,

z is the number of logical indexed tones and the number of physical indexed tones, and

wherein j, s, k, k², f_s^T(j,k), z are non-negative integers.

56. The wireless terminal of claim 55, wherein z is 113, T is a value in the set of {0, 1, 2}, s is an integer value in a set of at least 5 different integers, k is an integer greater than or equal to 0 and less than or equal to 59.

57. The wireless terminal of claim 55, wherein k=(L mod 4)*15+floor function ((t−

9)/7),

where;

L is a superslot index within a beaconslot and L is an integer in the range 0 to 7,

t is a symbol index of a superslot having an index range of 0 to 113 and t is an integer in the range 9 to 113.

58. The wireless terminal of claim 37, further comprising:

a receiver module for receiving downlink signals; and

a slope determination module for determining said cell identifier from downlink signals received from a base station.

59. The wireless terminal of claim 58, wherein said slope determination module includes information about signal patterns corresponding to different cell identifiers for use in determining the cell identifier from a pattern of high power signals received from said base station.

60. The wireless terminal of claim 59, wherein said high power signals from which a cell identifier is determined include pilot signals, beacon signals or a combination of pilot and beacon signals.

61. The wireless terminal claim 60, further comprising:

a sector type determination module for determining said sector type identifier from downlink signals received from the base station.

62. A method of implementing tone hopping in a frequency division multiplexed system, said system including at least one cell including multiple sectors, the method comprising the steps of:

determining a plurality of physical tone indexes, said physical indexes corresponding to physical tones to be used to transmit signals based on a tone hopping function which uses a cell identifier and a sector identifier to control the mapping of logical tones to physical tones as a function of time; and

receiving signals using said physical tones corresponding to the determined physical tone indexes.

63. The method of claim 62, wherein said tones are orthogonal frequency division multiplexing (OFDM) tones.

64. The method of claim 63, wherein said determining step is preformed once per dwell, each dwell including a fixed number of consecutive orthogonal frequency division multiplexing (OFDM) time periods.

65. The method of claim 62, wherein determining the plurality of physical tone indexes as a function of time includes using a quadratic time dependent parameter.

66. The method of claim 65, wherein determining the plurality of physical tone indexes as a function of time further includes using a linear time dependent parameter in addition to said quadratic time dependent parameter.

67. The method of claim 66, wherein different wireless terminals use different subsets of said physical tones, the method further comprising:

determining based on logical tone assignment information and said determined plurality of physical tone indexes which physical tones have been assigned to each of a plurality of wireless terminals from which signals have been received.

68. The method of claim 67, wherein said method is implemented in a base station

69. A base station for use in a frequency division multiplexed communications system including a multi-sector cell, the base station comprising:

a tone hopping module for determining a plurality of physical tone indexes, said physical indexes corresponding to physical tones to be used to transmit signals based on a tone hopping function which uses a cell identifier and a sector identifier to control the mapping of logical tones to physical tones as a function of time; and

a receiver for receiving signals on physical tones corresponding to the determined physical tone indexes.

70. The base station of claim 69, wherein said tones are orthogonal frequency division multiplexing (OFDM) tones.

71. The base station of claim 70, wherein said determining step is preformed once per dwell, each dwell including a fixed number of consecutive orthogonal frequency division multiplexing (OFDM) time periods.

72. The base station of claim 69, wherein said tone hopping module has a timing input for receiving a timing value used in generating a quadratic time dependent parameter used in determining the plurality of physical tone indexes as a function of time.

73. The base station of claim 72, wherein said tone hopping module further includes:

means for using a linear time dependent parameter, which is a function of said timing value, in addition to said quadratic time dependent parameter, when determining the plurality of physical tone indexes as a function of time.

74. The base station of claim 72, wherein different wireless terminals use different subsets of said physical tones, the method further comprising:

determining based on logical tone assignment information and said determined plurality of physical tone indexes which physical tones have been assigned to each of a plurality of wireless terminals from which signals have been received.