Methods and apparatus for measuring, communicating and/or using interference information

• US 8,811,512 B2
• Filed: 09/28/2010
• Issued: 08/19/2014
• Est. Priority Date: 06/21/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei Yurievitch, Khandekar, Aamod Dinkar, Palanki, Ravi, Prakash, Rajat
• Primary Examiner(s): Fan, Chieh M
• Assistant Examiner(s): Aghdam, Freshteh N
• Application Number:
  US12/892,578
• Publication Number:
  US 20110019770A1
• Time in Patent Office: 1,421 Days
• Field of Search: 375/260, 375/267, 375/269, 375/316, 375/295
• US Class Current: 375/267
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/247 where the output power of a terminal is based on a path parameter sent by another terminal
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

Wireless communications methods and apparatus are described. A communications apparatus, e.g., a base station, measures interference information, e.g., other sector interference information. The communications apparatus generates a preamble which includes a plurality of pilot symbols and at least one of the pilot symbols includes interference information. In some embodiments, the preamble is part of a superframe structure, e.g., a recurring superframe structure, including the preamble and a plurality of frames, at least some of the frames used to convey traffic data. The communications apparatus transmits the preamble, thus broadcasting the interference information to access terminals in the vicinity. An access terminal receives the preamble including a plurality of pilot signals, at least one of the pilot signals including interference information. The access terminal recovers the interference information from the received preamble and controls signal transmission based on the recovered interference information.

Claims

1. A method of operating a communications apparatus, the method comprising:

measuring interference; and

transmitting a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information.

2. The method of claim 1, wherein transmitting a preamble further includes:

transmitting as part of said preamble at least one symbol corresponding to a broadcast channel used to communicate system configuration information.

3. The method of claim 1, wherein said pilot symbols include acquisition pilots used for at least one of timing acquisition and sector identification.

4. The method of claim, 2, wherein said preamble includes more symbols used to communicate system configuration information than interference information.

5. The method of claim 2, wherein said preamble is a superframe preamble.

6. The method of claim 5, wherein said symbols in said superframe preamble include fewer tones per symbol than symbols used to communicate data as part of a frame within a body of said superframe.

7. The method of claim 2, wherein at least two symbols are used in said preamble to communicate interference information.

8. The method of claim 7, wherein the measuring of the interference includes:

measuring interference with respect to sectors other than a sector from which said preamble is transmitted.

9. The method of claim 1, further comprising, prior to transmitting the preamble:

generating a first pilot in at least some subcarriers of a first OFDM pilot symbol;

generating a second pilot in at least some subcarriers of a second OFDM pilot symbol;

generating interference information in at least some other subcarriers of the second OFDM pilot symbol; and

wherein said plurality of pilot symbols, included in said preamble, includes said generated first and second pilots.

10. The method of claim 9, wherein generating said second pilot includes:

using a scrambling sequence that is applied to the first pilot.

11. The method of claim 10, wherein generating said second pilot further includes multiplying a scrambling sequence used to generate the second pilot by an offset.

12. The method of claim 11, wherein said offset depends on said interference information.

13. The method of claim 12, wherein said offset has unit modulus.

14. The method of claim 9, wherein transmitting a preamble includes transmitting the first OFDM pilot symbol and the second OFDM pilot symbol as adjacent OFDM symbols in said preamble.

15. The method of claim 9 further comprising:

controlling pilot signal generation to be performed differently during an asynchronous mode of operation than during a semi-synchronous mode of operation, said second pilot signal being generated using a different function during said asynchronous mode of operation than during said semi-synchronous mode of operation.

16. The method of claim 1, wherein generating said pilot symbol further comprises:

incorporating the interference information into the at least one of said pilot symbols via a phase offset applied to multiple subcarriers.

17. The method of claim 16, wherein said phase offset is applied by performing a phase multiplication operation on an input pilot symbol which does not include interference information to generate said pilot symbol including interference information.

78. The method of claim 1, wherein the scrambling sequence applied to the at least one and the at least one other pilot symbols is generated from a PilotPhase quantity.

18. A wireless communications apparatus, the apparatus comprising:

an interference measurement module; and

a preamble generation module for generating a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information.

19. The apparatus of claim 18, further comprising:

a wireless transmitter module for transmitting said generated preamble.

20. The apparatus of claim 18, wherein said preamble generation module includes a first symbol generation module for generating at least one symbol corresponding to a broadcast channel used to communicate system configuration information.

21. The apparatus of claim 18, wherein said preamble generation module generates pilots which are acquisition pilots used for at least one of timing acquisition and sector identification.

22. The apparatus of claim 19, wherein said preamble generation module generates more symbols used to communicate system configuration information than interference information in the generated preamble.

23. The apparatus of claim 19, wherein said preamble is a superframe preamble;

and

wherein at least two symbols are used in said preamble to communicate interference information.

24. The apparatus of claim 23, wherein said interference measurement module is an other sector interference measurement module which measures interference with respect to sectors other than a sector from which said preamble is transmitted.

25. The apparatus of claim 18, wherein said preamble generation module includes:

a first pilot generation module for generating a first pilot in at least some subcarriers of a first OFDM pilot symbol;

a second pilot generation module for generating a second pilot in at least some subcarriers of a second OFDM pilot symbol;

an interference information generation module for generating interference information in at least some other subcarriers of the second OFDM pilot symbol; and

wherein said plurality of pilot symbols, included in said preamble, includes said generated first and second pilots.

26. The apparatus of claim 25, wherein said second pilot generation module generates the second pilot using a scrambling sequence that is applied to the first pilot generated by the first pilot generation module.

27. The apparatus of claim 26, wherein the second pilot generation module includes an offset module for applying an offset to a scrambling sequence used to generate the second pilot.

28. The apparatus of claim 25, wherein said transmitter transmits the first OFDM pilot symbol and the second OFDM pilot symbol as adjacent OFDM symbols in said preamble.

29. The apparatus of claim 25 further comprising:

a pilot generation mode control module for controlling the second pilot generation module to operate in one of a first and second mode of operation at a given time, said first mode corresponding to a communications apparatus asynchronous module of operation and said second mode corresponding to a communications apparatus semi-synchronous mode of operation, said second pilot generation module generating the second pilot differently during said first and second modes of operation.

30. A wireless communications apparatus, the apparatus comprising:

interference measurement means; and

means for generating a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information.

31. The apparatus of claim 30, further comprising:

means for transmitting said generated preamble.

32. The apparatus of claim 30, wherein said means for generating includes first symbol generation means for generating at least one symbol corresponding to a broadcast channel used to communicate system configuration information.

33. The apparatus of claim 30, wherein said means for generating generates pilots which are acquisition pilots used for at least one of timing acquisition and sector identification.

34. The apparatus of claim 30, wherein said means for generating includes:

first pilot generation means for generating a first pilot in at least some subcarriers of a first OFDM pilot symbol;

second pilot generation means for generating a second pilot in at least some subcarriers of a second OFDM pilot symbol;

interference information generation means for generating interference information in at least some other subcarriers of the second OFDM pilot symbol; and

wherein said plurality of pilot symbols, included in said preamble, includes said generated first and second pilots.

35. An apparatus comprising:

a processor configured to;

measure interference,

generate a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information, and

operate a transmitter to transmit the preamble; and

memory coupled to the processor.

36. The apparatus of claim 35, wherein said processor is further configured to:

operate the transmitter to transmit as part of said preamble at least one symbol corresponding to a broadcast channel used to communicate system configuration information.

37. The apparatus of claim 35, wherein said pilot symbols include acquisition pilots used for at least one of timing acquisition and sector identification.

38. The apparatus of claim 35, wherein said processor is further configured to, prior to the transmission of the preamble:

generate a first pilot in at least some subcarriers of a first OFDM pilot symbol;

generate a second pilot in at least some subcarriers of a second OFDM pilot symbol;

generate interference information in at least some other subcarriers of the second OFDM pilot symbol; and

wherein said plurality of pilot symbols, included in said preamble, includes said generated first and second pilots.

39. The apparatus of claim 38, wherein said processor is further configured to control pilot signal generation to be performed differently during an asynchronous mode of operation than during a semi-synchronous mode of operation, said second pilot signal being generated using a different function during said asynchronous mode of operation than during said semi-synchronous mode of operation.

40. A non-transitory computer readable medium embodying machine executable instructions for controlling a communications apparatus to implement a method of communicating with another communications device, the method comprising:

measuring interference; and

transmitting a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information.

41. The computer readable medium of claim 40, further embodying machine executable instructions for:

transmitting as part of said preamble at least one symbol corresponding to a broadcast channel used to communicate system configuration information.

42. The computer readable medium of claim 40, wherein said pilot symbols include acquisition pilots used for at least one of timing acquisition and sector identification.

43. The computer readable medium of claim 40, further embodying machine executable instructions for, prior to transmitting the preamble:

generating a first pilot in at least some subcarriers of a first OFDM pilot symbol;

generating a second pilot in at least some subcarriers of a second OFDM pilot symbol;

generating interference information in at least some other subcarriers of the second OFDM pilot symbol; and

wherein said plurality of pilot symbols, included in said preamble, includes said generated first and second pilots.

44. The computer readable medium of claim 43 further embodying machine executable instructions for:

controlling pilot signal generation to be performed differently during an asynchronous mode of operation than during a semi-synchronous mode of operation, said second pilot signal being generated using a different function during said asynchronous mode of operation than during said semi-synchronous mode of operation.

45. A method of operating an access terminal, the method comprising:

receiving a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information;

recovering the interference information from the received preamble; and

controlling signal transmission based on the recovered interference information.

46. The method of claim 45, wherein recovering said interference information includes:

using preamble structure information to determine the location of said at least one pilot symbol including, interference information in said received preamble.

47. The method of claim 46, further comprising:

performing a timing acquisition operation using at least one of said pilot symbols included in the received preamble.

48. The method of claim 46, further comprising:

identifying a sector from which said received preamble was transmitted from said at least one of said pilot symbols including interference information that is included in the received preamble.

49. The method of claim 46, wherein said received preamble includes more symbols used to communicate system configuration information than interference information.

50. The method of claim 46, wherein said received preamble is a superframe preamble.

51. The method of claim 50, wherein said symbols in said superframe preamble include fewer tones per symbol than symbols used to communicate data as part of a frame within a body of said superframe.

52. The method of claim 46, wherein at least two symbols are used in said received preamble to communicate interference information;

and

wherein recovering interference information from the received preamble includes recovering interference information from said at least two symbols.

53. The method of claim 52, wherein recovering interference information includes performing an unscrambling operation using a scrambling sequence that is applied to a first pilot to generate a second pilot.

54. An access terminal, comprising:

a receiver for receiving a preamble, said preamble having a preamble structure including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information;

an interference information recovery module for recovering from the plurality of pilot symbols the interference information from the received preamble based on the preamble structure; and

a transmission control module for controlling signal transmission based on the recovered interference information.

55. The access terminal of claim 54, further comprising:

a memory including stored preamble structure information indicating the location of said at least one pilot symbol including interference information in a preamble; and

wherein said interference recovery module uses the stored preamble structure information to determine the location of said at least one pilot symbol including interference information in said received preamble.

56. The access terminal of claim 55, further comprising:

a timing acquisition module for performing a timing acquisition operation using at least one of said pilot symbols that is included in the received preamble.

57. The access terminal of claim 55, further comprising:

a sector identification module for identifying a sector from which said received preamble was transmitted from said at least one of said pilot symbols including interference information that is included in the received preamble.

58. The access terminal of claim 55, wherein said received preamble includes more symbols used to communicate system configuration information than interference information.

59. The access terminal of claim 55, wherein said received preamble is a superframe preamble.

60. The access terminal of claim 59, wherein said symbols in said superframe preamble include fewer tones per symbol than symbols used to communicate data as part of a frame within a body of said superframe.

61. The access terminal of claim 55, wherein at least two symbols are used in said received preamble to communicate interference information;

and

wherein said interference information recovery module recovers interference information from said at least two symbols.

62. The access terminal of claim 61, wherein said interference information recovery module includes:

an unscrambling module for performing an unscrambling operation using a scrambling sequence that is applied to a first pilot to generate a second pilot.

63. An access terminal, comprising:

receiver means for receiving a preamble, said preamble having a preamble structure including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information;

means for recovering from the plurality of pilot symbols the interference information from the received preamble based on the preamble structure; and

means for controlling signal transmission based on the recovered interference information.

64. The access terminal of claim 63, further comprising:

memory means including stored preamble structure information indicating the location of said at least one pilot symbol including interference information in a preamble; and

wherein said means for recovering uses the stored preamble structure information to determine the location of said at least one pilot symbol including interference information in said received preamble.

65. The access terminal of claim 64, further comprising:

means for performing a timing acquisition operation using at least one of said pilot symbols that is included in the received preamble.

66. The access terminal of claim 64, wherein at least two symbols are used in said received preamble to communicate interference information;

and

wherein said means for recovering recovers interference information from said at least two symbols.

67. The access terminal of claim 66, wherein said means for recovering includes:

means for performing an unscrambling operation using a scrambling sequence that is applied to a first pilot to generate a second pilot.

68. An apparatus comprising:

a processor configured to;

receive a preamble, said preamble having a preamble structure including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information,

recover from the plurality of pilot symbols the interference information from the received preamble based on the preamble structure, and

control signal transmission based on the recovered interference information; and

a memory coupled to the processor.

69. The apparatus of claim 68, wherein the processor is further configured to, in recovering said interference information:

use preamble structure information to determine the location of said at least one pilot symbol including interference information in said received preamble.

70. The apparatus of claim 69, wherein the processor is further configured to identify a sector from which said received preamble was transmitted from said at least one of said pilot symbols including interference information that is included in the received preamble.

71. The apparatus of claim 69, wherein at least two symbols are used in said received preamble to communicate interference information;

and

wherein the processor is further configured to, in recovering interference information from the received preamble, recover interference information from said at least two symbols.

72. The apparatus of claim 71, wherein the processor is further configured to, in recovering interference information, perform an unscrambling operation using a scrambling sequence that is applied to a first pilot to generate a second pilot.

73. A non-transitory computer readable medium embodying machine executable instructions for controlling an access terminal to implement a method of communicating with another communications device, the method comprising:

receiving a preamble, said preamble including a plurality of pilot symbols, at least one of said pilot symbols including interference information, wherein the at least one of said pilot symbols including the interference information is scrambled by applying the same scrambling sequence bits, in value and number, that are applied to at least one other pilot symbol among the plurality of pilot symbols included in said preamble that does not include the interference information;

recovering the interference information from the received preamble; and

controlling signal transmission based on the recovered interference information.

74. The computer readable medium of claim 73, further embodying machine executable instructions for:

using preamble structure information to determine the location of said at least one pilot symbol including interference information in said received preamble.

75. The computer readable medium of claim 74, further embodying machine executable instructions for:

identifying a sector from which said received preamble was transmitted from said at least one of said pilot symbols including interference information that is included in the received preamble.

76. The computer readable medium of claim 74, wherein at least two symbols are used in said received preamble to communicate interference information;

and

further embodying machine executable instructions for, in recovering interference information from the received preamble, recovering interference information from said at least two symbols.

77. The computer readable medium of claim 76, further embodying machine executable instructions for, in recovering interference information, performing an unscrambling operation using a scrambling sequence that is applied to a first pilot to generate a second pilot.