Softer and soft handoff in an orthogonal frequency division wireless communication system

• US 20060291371A1
• Filed: 05/18/2005
• Published: 12/28/2006
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Naguib, Ayman Fawzy, Gorokhov, Alexei, Sutivong, Arak, Ji, Tingfang, Gore, Dhananjay
• Granted Patent: US 7,768,979 B2
• Time in Patent Office: Days
• US Class Current: 370/208
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0012 Hopping in multicarrier systems for frequency hopping in spread spectrum systems H04B1/713
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0069 Allocation based on distance or geographical location allocation based on terminal or device properties in general, H04W72/51
• CPC Class Codes: H04W 36/00692 using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO] allocation of physical resources in CoMP or in CA H04L5/0035
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00

Abstract

Transmission patterns for pilot symbols transmitted from a mobile station or base station are provided. The patterns may be selected according to a location of the mobile station with respect to one or more antennas are provided. In some aspects, the pattern may be selected based upon the distance between the mobile station and the one or more antennas. In other aspect, the pattern may be based upon whether the mobile station is in handoff.

Claims

1. A wireless communication apparatus, comprising:

a plurality of antenna groups each of which corresponds to a different area of a plurality of areas;

a memory that stores a plurality of indicators each corresponding to a group of pilot symbols of a plurality of groups of pilot symbols; and

a circuit coupled with the plurality of antenna groups that selects an indicator of the plurality of indicators, to be transmitted to a wireless communication device in communication with one of the plurality of antenna groups based upon a location of the wireless communication device within the area, to assign the wireless communication device to transmit a group of pilot symbols to the wireless communication apparatus.

2. The wireless communication apparatus of claim 1, wherein the plurality of areas are contiguous areas and wherein the circuit selects a specific one of the indicators when the wireless communication device is near a boundary between two or more contiguous areas.

3. The wireless communication apparatus of claim 2, wherein the wireless communication apparatus decodes a same symbol received, at antennas from two different groups of the antenna groups, from the wireless communication device.

4. The wireless communication apparatus of claim 2, wherein the circuit selects the specific one of the indicators, to be transmitted to a second wireless communication device in communication with one of the plurality of antenna groups, when the second wireless communication device is near a boundary between two or more contiguous areas.

5. The wireless communication apparatus of claim 2, wherein the circuit selects a second specific indicator, to be transmitted to the second wireless communication device in communication with one of the plurality of antenna groups, when the second wireless communication device is near a boundary between another two or more contiguous areas that are different than the two or more contiguous areas.

6. The wireless communication apparatus of claim 2, wherein each group of pilot symbols correspond to a different scrambling sequence of a plurality of scrambling sequences and wherein a group corresponding to the specific one of the indicators corresponds to a pre-determined scrambling sequence based upon the location.

7. The wireless communication apparatus of claim 2, wherein each group of pilot symbols correspond to a pattern of pilot symbol locations of a plurality of patterns of pilot symbol locations and wherein a group corresponding to the specific one of the indicators corresponds to a pre-determined pattern of pilot symbol locations that are based upon the location of the wireless communication device.

8. The wireless communication apparatus of claim 1, wherein the circuit comprises a processor.

9. The wireless communication apparatus of claim 1, wherein the wireless communication apparatus transmits signals according to an OFDM communication protocol.

10. The wireless communication apparatus of claim 1, wherein the circuit further utilizes quality of service requirements to select the indicator of the plurality of indicators.

11. The wireless communication apparatus of claim 1, wherein the circuit determines the location of the wireless communication device based upon channel quality information received from the wireless communication device.

12. The wireless communication apparatus of claim 1, wherein the plurality of groups of pilot symbols are each orthogonal to each other.

13. The wireless communication apparatus of claim 1, wherein the circuit decodes data symbols associated with the pilot symbols received at each of the plurality of antenna groups for each of the group of pilot symbols of the plurality of groups of pilot symbols and then combines decoded data symbols for a same group of pilot symbols received at each of the plurality of antenna groups.

14. A wireless communication apparatus, comprising:

a plurality of antenna groups;

a memory that stores a plurality of pilot pattern indicators each corresponding to a plurality of pilot symbols; and

a circuit coupled with the plurality of antenna groups that selects a pilot pattern indicator of the plurality of pilot pattern indicators to be transmitted to a wireless communication device based upon whether the wireless communication device is in handoff.

15. The wireless communication apparatus of claim 14, wherein the memory stores a number of pilot indicators equal to the number of antenna groups.

16. The method of claim 14, wherein the memory stores a number of pilot pattern indicators equal to three times the number of antenna groups.

17. The wireless communication apparatus of claim 14, wherein the wireless communication apparatus transmits signals according to an OFDM communication protocol.

18. The wireless communication apparatus of claim 14, wherein the circuit comprises a processor.

19. The wireless communication apparatus of claim 14, wherein the circuit determines the whether the wireless communication device is in handoff is based upon channel quality information received from the wireless communication device.

20. The wireless communication apparatus of claim 14, wherein each group of the plurality of pilot symbols corresponds to a different scrambling sequence of a plurality of scrambling sequences and wherein the pilot pattern indicator corresponds to a pre-determined handoff scrambling sequence.

21. The wireless communication apparatus of claim 14, wherein each group of the plurality of pilot symbols corresponds to pilot symbol locations of a plurality of patterns of pilot symbol locations and wherein a group corresponding to the pilot pattern indicator corresponds to a pre-determined handoff pilot pattern.

22. The wireless communication apparatus of claim 14, wherein the circuit selects the pilot pattern indicator of the plurality of pilot pattern indicators to be transmitted to the wireless communication device based upon whether the wireless communication device is in handoff and the antenna group with which the wireless communication device is currently communicating.

23. The wireless communication apparatus of claim 14, wherein each of the plurality of pilot symbols corresponding to each of the plurality of pilot pattern indicators is orthogonal with respect to each other plurality of pilot symbols corresponding to each other of the plurality of pilot pattern indicators.

24. The wireless communication apparatus of claim 14, wherein the circuit decodes data symbols received at each of the plurality of antenna groups associated with each of the groups of the plurality of pilot symbols corresponding to a pilot symbol indicator of the plurality of pilot symbol indicators and then combines decoded data symbols for a same group of the plurality of pilot symbols received at each of the plurality of antenna groups.

25. A method of selecting a pilot pattern for a wireless communication device comprising:

determining a location of a wireless communication device with respect to an antenna;

selecting a pilot pattern of a plurality of pilot patterns to be utilized for transmission by the wireless communication device based upon the location; and

transmitting an indicator of the pilot pattern to the wireless communication device.

26. The method of claim 25, further comprising determining a location of the wireless communication device with respect to another antenna, and wherein selecting the pilot pattern comprises selecting the pilot pattern based upon the location with respect to the antenna and the location with respect to the another antenna.

27. The method of claim 25, wherein determining the location with respect to the antenna comprises determining a distance between the antenna and the wireless communication device and determining the location with respect to the another antenna comprises determining a distance between the another antenna and the wireless communication device.

28. The method of claim 25, wherein determining the location comprises determining the location based upon channel quality information.

29. The method of claim 28, wherein determining the location based upon channel quality information comprises determining a noise level.

30. The method of claim 28, wherein determining the location based upon channel quality information comprises determining a signal to noise ratio.

31. The method of claim 25, wherein determining the location comprises determining the location with respect to a sector boundary.

32. The method of claim 31, wherein selecting the pilot pattern comprises selecting an edge pilot pattern if the location is sufficiently close to the sector boundary.

33. The method of claim 25, wherein determining the location with respect to the antenna comprises determining a distance between the antenna and the wireless communication device.

34. The method of claim 25, wherein determining the distance comprises comparing a signal to noise ratio to a reference.

35. The method of claim 25, wherein selecting comprises selecting the pilot pattern based upon the location and the antenna group with which the wireless communication device is currently communicating.

36. The method of claim 25, wherein each pilot pattern of the plurality of pilot patterns is orthogonal with respect to each other pilot pattern of the plurality of pilot patterns.

37. The method of claim 25, wherein each pilot pattern of the plurality of pilot patterns is assigned a different scrambling sequence of a plurality of scrambling sequence than each other pilot pattern of the plurality of pilot patterns.

38. A wireless communication apparatus comprising:

means for determining a location of a wireless communication device with respect to an antenna of the wireless communication apparatus;

means for selecting a pilot pattern of a plurality of pilot patterns to be utilized for transmission by the wireless communication device based upon the location; and

a transmitter configured to transmit signals including the indicator of the pilot pattern.

39. The wireless communication apparatus of claim 38, further comprising means for determining a location of the wireless communication device with respect to another antenna of the wireless communication apparatus, and wherein the means for selecting comprises means for selecting the pilot pattern based upon the location with respect to the antenna and the location with respect to the another antenna.

40. The wireless communication apparatus of claim 39, wherein the means for determining the location with respect to the antenna comprises means for determining a distance between the antenna and the wireless communication device and the means for determining the location with respect to the another antenna comprises means for determining a distance between the another antenna and the wireless communication device.

41. The wireless communication apparatus of claim 38, wherein the means for determining the location comprises means for determining the location based upon channel quality information.

42. The wireless communication apparatus of claim 38, wherein the means for determining the location comprises means for determining the location with respect to a sector boundary.

43. The wireless communication apparatus of claim 38, wherein each pilot pattern of the plurality of pilot patterns is orthogonal with respect to each other pilot pattern of the plurality of pilot patterns.

44. The wireless communication apparatus of claim 38, wherein each pilot pattern of the plurality of pilot patterns is assigned a different scrambling sequence of a plurality of scrambling sequence than each other pilot pattern of the plurality of pilot patterns.

45. The wireless communication apparatus of claim 38, further comprising means for decoding data symbols received at each of the plurality of antenna groups associated with each of the pilot pattern of the plurality of pilot patterns and means for combining decoded symbols associated with a same pilot pattern received at each of the plurality of antenna groups.

46. A method of selecting a pilot pattern for a wireless communication device comprising:

determining whether a wireless communication device is in handoff;

selecting a pilot pattern of a plurality of pilot patterns to be utilized for transmission by the wireless communication device based upon whether the wireless communication device is in handoff; and

transmitting an indicator of the pilot pattern to the wireless communication device.

47. The method of claim 46, further comprising determining which antenna group the wireless communication device is in communication, and wherein selecting the pilot pattern further comprises selecting the pilot pattern based upon the antenna group the wireless communication device is in communication.

48. The method of claim 46, wherein determining whether the wireless communication device is in handoff is based upon channel quality information received from the wireless communication device.

49. The method of claim 46, wherein each of the plurality of pilot patterns corresponds to a different scrambling sequence of a plurality of scrambling sequences and wherein the indicator corresponds to a pre-determined handoff scrambling sequence.

50. The method of claim 46, wherein each of the plurality of pilot patterns corresponds to pilot symbol locations of a plurality of patterns of pilot symbol locations and wherein the indicator corresponds to a pre-determined handoff pilot pattern.

51. The method of claim 46, wherein determining whether the wireless communication device is in handoff comprises determining whether the wireless communication device is in handoff is based upon channel quality information.

52. The method of claim 46, wherein determining whether the wireless communication device is in handoff comprises determining whether the wireless communication device is in handoff is based upon whether a request for handoff has been provided.

53. The method of claim 46, wherein each pilot pattern of the plurality of pilot patterns is orthogonal with respect to each other pilot pattern of the plurality of pilot patterns.

54. The method of claim 46, wherein each pilot pattern of the plurality of pilot patterns is assigned a different scrambling sequence of a plurality of scrambling sequence than each other pilot pattern of the plurality of pilot patterns.

55. A wireless communication apparatus, comprising:

a plurality of antenna groups;

a memory that stores a plurality of indicators each corresponding to a pilot pattern of a plurality of pilot patterns; and

a circuit coupled with the plurality of antenna groups that selects an indicator of the plurality of indicators, to be transmitted to a wireless communication device in communication with one of the plurality of antenna groups based upon which antenna group is in communication with the wireless communication device.

56. The wireless communication apparatus of claim 55, wherein the wireless communication apparatus decodes pilot symbols received, at antennas from two different groups of the antenna groups, from the wireless communication device.

57. The wireless communication apparatus of claim 55, wherein the circuit selects a second specific indicator, to be transmitted to a second wireless communication device in communication with one of the plurality of antenna groups, when the second wireless communication device is in communication with a different antenna group than the wireless communication device.

58. The wireless communication apparatus of claim 55, wherein the circuit comprises a processor.

59. The wireless communication apparatus of claim 55, wherein the wireless communication apparatus transmits signals according to an OFDM communication protocol.

60. The wireless communication apparatus of claim 55, wherein at least two pilot patterns are assigned for communication between wireless communication devices and each antenna group.

61. The wireless communication apparatus of claim 57, wherein the at least two pilot patterns are different between each antenna group.

62. The wireless communication apparatus of claim 55, wherein only one pilot pattern is assigned for communication between wireless communication devices and each antenna group.

63. The wireless communication apparatus of claim 55, wherein the circuit decodes pilot symbols received at each of the plurality of antenna groups for each pilot pattern of the plurality of pilot patterns and then combines decoded pilot symbols for a same pilot pattern received at each of the plurality of antenna groups.

64. A wireless communication apparatus, comprising:

a plurality of antenna groups each of which corresponds to a different area of a plurality of areas in which a wireless communication apparatus is capable of communication;

a memory that stores a plurality of indicators each corresponding to a pilot pattern of a plurality of pilot patterns, at least one of the plurality of pilot patterns corresponding to a handoff; and

a circuit coupled with the plurality of antenna groups and the memory, the circuit determining if a pilot pattern received at one or more of the antenna groups corresponds to the at least one pilot pattern and combining processed data symbols, associated with the at least one pilot pattern, received at the one or more antenna groups .

65. The wireless communication apparatus of claim 64, wherein the circuit performs combining by using maximum ratio combining.

66. The wireless communication apparatus of claim 64, wherein the circuit assigns the at least one pilot pattern to a wireless communication device based upon a determination as to whether the wireless communication device is in handoff.

67. The wireless communication apparatus of claim 66, wherein the circuit whether the wireless communication device is in handoff based upon a request for handoff.

68. The wireless communication apparatus of claim 66, wherein the circuit whether the wireless communication device is in handoff based upon a location of the wireless communication device.

69. The wireless communication apparatus of claim 68, wherein the circuit determines the location of the wireless communication device based upon a signal to noise ratio.

70. The wireless communication apparatus of claim 64, wherein the circuit comprises a processor.

71. The wireless communication apparatus of claim 64, wherein the wireless communication apparatus transmits signals according to an OFDM communication protocol.

72. The wireless communication apparatus of claim 64, wherein the plurality of groups of pilot symbols are each orthogonal to each other.

73. The wireless communication apparatus of claim 64, wherein each antenna group corresponds to a sector of a base station.

74. The wireless communication apparatus of claim 64, wherein each antenna group includes a single antenna.