Frequency-independent spatial processing for wideband MISO and MIMO systems

• US 7,894,538 B2
• Filed: 06/19/2006
• Issued: 02/22/2011
• Est. Priority Date: 08/27/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Howard, Steven J., Ketchum, John W., Walton, J. Rodney, Wallace, Mark S.
• Primary Examiner(s): KIM, KEVIN
• Application Number:
  US11/471,415
• Publication Number:
  US 20060274844A1
• Time in Patent Office: 1,709 Days
• Field of Search: 375/260, 375/299, 375/347
• US Class Current: 375/260
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Frequency-independent eigensteering in MISO and MIMO systems are described. For principal mode and multi-mode eigensteering, a correlation matrix is computed for a MIMO channel based on channel response matrices and decomposed to obtain N_S frequency-independent steering vectors for N_S spatial channels of the MIMO channel. N_D data symbol streams are transmitted on N_D best spatial channels using N_D steering vectors, where N_D=1 for principal mode eigensteering and N_D>1 for multi-mode eigensteering. For main path eigensteering, a data symbol stream is transmitted on the best spatial channel for the main propagation path (e.g., with the highest energy) of the MIMO channel. For receiver eigensteering, a data symbol stream is steered toward a receive antenna based on a steering vector obtained for that receive antenna. For all eigensteering schemes, a matched filter is derived for each receive antenna based on the steering vector(s) and channel response vectors for the receive antenna.

Claims

1. A method of performing spatial processing in a wireless communication system, comprising:

obtaining a plurality of channel response matrices for a channel response of a communication channel in the wireless communication system;

computing a correlation matrix for the communication channel based on the plurality of channel response matrices; and

decomposing the correlation matrix to obtain steering information for at least one spatial channel of the communication channel, wherein the steering information is used by a transmitting entity for spatial processing of a data stream sent on the at least one spatial channel associated with the steering information.

2. The method of claim 1, wherein the wireless communication system is a multiple-input multiple-output (MIMO) communication system, and the communication channel is a MIMO channel.

3. The method of claim 1, wherein the steering information includes at least one steering vector.

4. The method of claim 1, wherein the spatial processing is frequency-independent spatial processing.

5. The method of claim 1, wherein the plurality of channel response matrices comprise a plurality of channel impulse response matrices for a plurality of time delays of a channel impulse response of the communication channel.

6. The method of claim 1, wherein the plurality of channel response matrices comprise a plurality of channel frequency response matrices for a channel frequency response for a plurality of subbands of the communication channel.

7. The method of claim 1, wherein the computing the correlation matrix for the communication channel comprises:

computing a correlation matrix of each of the plurality of channel response matrices to obtain a plurality of correlation matrices for the plurality of channel response matrices; and

summing the plurality of correlation matrices for the plurality of channel response matrices to obtain the correlation matrix for the communication channel.

8. The method of claim 5, wherein the computing the correlation matrix for the communication channel comprises:

determining energy of each of the plurality of channel impulse response matrices;

identifying a channel impulse response matrix with highest energy among the plurality of channel impulse response matrices; and

computing a correlation matrix of the channel impulse response matrix with the highest energy to generate the correlation matrix for the communication channel.

9. The method of claim 1, wherein eigenvalue decomposition of the correlation matrix is performed to obtain the steering information for the at least one spatial channel of the communication channel.

10. The method of claim 1, further comprising sending the steering information as feedback information to the transmitting entity.

11. The method of claim 1, wherein the steering information is used by the transmitting entity to generate a plurality of transmit chip streams for at least one data stream sent on the at least one spatial channel of the communication channel, and wherein the plurality of transmit chip streams are transmitted from a plurality of transmit antennas at the transmitting entity.

12. The method of claim 1, wherein the spatial processing is performed by the transmitting entity in the time-domain on a stream of time-domain chips generated for the data stream by OFDM modulation.

13. The method of claim 1, wherein the spatial processing is performed by the transmitting entity in the frequency-domain for each of a plurality of subbands on data symbols generated for the data steam.

14. The method of claim 1, further comprising:

obtaining, from the plurality of channel response matrices, a plurality of channel response vectors for each of a plurality of receive antennas at a receiving entity; and

deriving a matched filter for each of the plurality of receive antennas based on the steering information and the plurality of channel response vectors for the respective receive antenna.

15. The method of claim 14, wherein the matched filter for each of the plurality of receive antennas is used to maximize received signal-to-noise ratio (SNR) for the respective receive antenna.

16. The method of claim 14, further comprising filtering a plurality of received symbol streams for the plurality of receive antennas with the plurality of matched filters.

17. The method of claim 16, wherein the plurality of channel response matrices comprise a plurality of channel impulse response matrices for a plurality of time delays of a channel impulse response of the communication channel, and wherein the filtering is performed in the time domain with a plurality of time-domain matched filters derived for the plurality of receive antennas based on the steering information and the plurality of channel impulse response matrices.

18. The method of claim 16, wherein the plurality of channel response matrices comprise a plurality of channel frequency response matrices for a channel frequency response for a plurality of subbands of the communication channel, and wherein the filtering is preformed in the frequency domain with a plurality of frequency-domain matched filters derived for the plurality of receive antennas based on the steering information and the plurality of channel frequency response matrices.

19. The method of claim 3, wherein one steering vector is obtained and used by the transmitting entity for the spatial processing of one data stream.

20. The method of claim 19, further comprising:

deriving a matched filter for each of a plurality of receive antennas at a receiving entity based on the one steering vector and a plurality of channel response vectors for the receive antenna, wherein the plurality of channel response vectors for each receive antennas are obtained from the plurality of channel response matrices;

filtering a plurality of received symbol streams for the plurality of receive antennas with the plurality of matched filters to obtain a plurality of filtered symbol streams; and

combining the plurality of filtered symbol streams to obtain a detected symbol stream for the one data strewn sent by the transmitting entity.

21. The method of claim 20, further comprising performing equalization on the detected symbol stream to obtain a recovered symbol stream for the one data stream.

22. The method of claim 3, wherein a plurality of steering vectors are obtained and used by the transmitting entity for the spatial processing of a plurality of data streams sent on a plurality of spatial channels associated with the plurality of steering vectors.

23. The method of claim 22, further comprising:

deriving a matched filter for each of a plurality of receive antennas at a receiving entity based on the plurality of steering vectors and a plurality of channel response vectors for the receive antenna, wherein the plurality of channel response vectors for each receive antenna are obtained from the plurality of channel response matrices;

filtering a plurality of received symbol streams for the plurality of receive antennas with the plurality of matched filters to obtain a plurality of filtered symbol substreams; and

combining the plurality of filtered symbol substreams to obtain a plurality of detected symbol steams for the plurality of data streams sent by the transmitting entity.

24. The method of claim 23, further comprising performing space-time equalization for the plurality of detected symbol streams to obtain a plurality of recovered symbol streams for the plurality of data streams.

25. The method of claim 24, wherein the space-time equalization is preformed with a minimum mean square error linear equalizer (MMSE-LE), a decision feedback equalizer (DFE), or a maximum likelihood sequence estimator (MLSE).

26. An apparatus in a wireless communication system, comprising:

a channel estimator configured to obtain a plurality of channel response matrices for a channel response of a communication channel in the wireless communication system; and

a controller configured to compute a correlation matrix for the communication channel based on the plurality of channel response matrices and configured to decompose the correlation matrix to obtain steering information for at least one spatial channel of the communication channel, wherein the steering information is used by a transmitting entity for spatial processing of a data stream sent on the at least spatial channel associated with the steering information.

27. The apparatus of claim 26, wherein the wireless communication system is a multiple-input multiple-output (MIMO) communication system, and the communication channel is a MIMO channel.

28. The apparatus of claim 26, wherein the steering information includes at least one steering vector.

29. The apparatus of claim 26, wherein the spatial processing is frequency-independent spatial processing.

30. The apparatus of claim 26, wherein the controller is configured to compute a correlation matrix of each of the plurality of channel response matrices to obtain a plurality of correlation matrices for the plurality of channel response matrices, and is configured to sum the plurality of correlation matrices to obtain the correlation matrix for the communication channel.

31. The apparatus of claim 26, wherein the plurality of channel response matrices comprise a plurality of channel impulse response matrices for a plurality of time delays of a channel impulse response of the communication channel, and wherein the controller is configured to determine energy of each of the plurality of channel impulse response matrices and configured to compute a correlation matrix of a channel impulse response matrix with highest energy among the plurality of channel impulse response matrices to obtain the correlation matrix for the communication channel.

32. The apparatus of claim 26, further comprising:

a plurality of matched filters for a plurality of receive antennas, one matched filter for each receive antenna, each matched filter is configured to filter a received symbol stream for an associated receive antenna to obtain a filtered symbol stream, wherein the matched filter for each receive antenna is derived based on the steering information and a plurality of channel response vectors for the receive antenna, and wherein the plurality of channel response vectors for each receive antenna are obtained from the plurality of channel response matrices; and

a combiner configured to combine a plurality of filtered symbol streams from the plurality of matched filters to obtain at least one detected symbol stream for at least one data steam sent by the transmitting entity.

33. An apparatus in a wireless communication system, comprising:

means for obtaining a plurality of channel response matrices for a channel response of a communication channel in the wireless communication system;

means for computing a correlation matrix for the communication channel based on the plurality of channel response matrices; and

means for decomposing the correlation matrix to obtain steering information for at least one spatial channel of the communication channel, wherein the steering information is used by a transmitting entity for spatial processing of a data stream sent on the at least one spatial channel associated with the steering information.

34. The apparatus of claim 33, wherein the wireless communication system is a multiple-input multiple-output (MIMO) communication system, and the communication channel is a MIMO channel.

35. The apparatus of claim 33, wherein the steering information includes at least one steering vector.

36. The apparatus of claim 33, wherein the spatial processing is frequency-independent spatial processing.

37. The apparatus of claim 33, wherein the means for computing the correlation matrix comprises:

means for computing a correlation matrix of each of the plurality of channel response matrices to obtain a plurality of correlation matrices for the plurality of channel response matrices; and

means for summing the plurality of correlation matrices to obtain the correlation matrix for the communication channel.

38. The apparatus of claim 33, wherein the plurality of channel response matrices comprise a plurality of channel impulse response matrices for a plurality of time delays of a channel impulse response of the communication channel.

39. The apparatus of claim 38, wherein the means for computing the correlation matrix comprises:

means for determining energy of each of the plurality of channel impulse response matrices; and

means for computing a correlation matrix of a channel impulse response matrix with highest energy among the plurality of channel impulse response matrices to obtain the correlation matrix for the communication channel.

40. A processor readable media for storing instructions operable to:

receive a plurality of channel response matrices for a channel response of a communication channel in a wireless communication system;

compute a correlation matrix for the communication channel based on the plurality of channel response matrices; and

decompose the correlation matrix to obtain steering information for at least one spatial channel of the communication channel, wherein the steering information is used by a transmitting entity for spatial processing of a data stream sent on the at least one spatial channel associated with the steering information.

41. The processor readable media of claim 40, wherein the wireless communication system is a multiple-input multiple-output (MIMO) communication system, and the communication channel is a MIMO channel.

42. The processor readable media of claim 40, wherein the steering information includes at least one steering vector.

43. The processor readable media of claim 40, wherein the spatial processing is frequency-independent spatial processing.

44. The processor readable media of claim 40, further storing instructions operable to:

compute a correlation matrix of each of the plurality of channel response matrices to obtain a plurality of correlation matrices for the plurality of channel response matrices; and

sum the plurality of correlation matrices to obtain the correlation matrix for the communication channel.

45. The processor readable media of claim 40, wherein the plurality of channel response matrices comprise a plurality of channel impulse response matrices for a plurality of time delays of a channel impulse response of the communication channel.

46. The processor readable media of claim 45, further storing instructions operable to:

compute energy of each of the plurality of channel impulse response matrices; and

compute a correlation matrix of a channel impulse response matrix with highest energy among the plurality of channel impulse response matrices to obtain the correlation matrix for the communication channel.

47. A method of performing spatial processing in a communication system, comprising:

obtaining a plurality of channel impulse response matrices for a communication channel in the wireless communication system, wherein the plurality of channel impulse response matrices comprise a plurality of time delays of a channel impulse response of the communication channel;

computing energy of each of the plurality of channel impulse response matrices;

identifying a channel impulse response matrix with highest energy among the plurality of channel impulse response matrices as a channel impulse response matrix for a main, path of the communication channel;

computing a correlation matrix of the channel impulse response matrix for the main path; and

decomposing the correlation matrix to obtain steering information for a spatial channel of the main path, wherein the steering information is used by a transmitting entity for spatial processing of a data stream sent via the communication channel.

48. The method of claim 47, wherein the wireless communication system is a multiple-input multiple-output (MIMO) communication system, and the communication channel is a MIMO channel.

49. The method of claim 47, wherein the steering information includes at least one steering vector.

50. The method of claim 47, wherein the spatial processing is frequency-independent spatial processing.

51. The method of claim 47, wherein eigenvalue decomposition of the correlation matrix for the main path is performed to obtain the steering information for the spatial channel of the main path.

52. The method of claim 47, further comprising:

deriving a matched filter for each of a plurality of receive antennas at a receiving entity based on the steering information and a plurality of channel impulse response vectors for the receive antenna, wherein the plurality of channel impulse response vectors for each receive antenna are obtained from the plurality of channel impulse response matrices; and

filtering a plurality of received symbol streams for the plurality of receive antennas with the plurality of matched filters.

53. A method of performing spatial processing in a wireless communication system with a plurality of transmit antennas at a transmitting entity and a plurality of receive antennas at a receiving entity, the method comprising:

obtaining a plurality of sets of channel response vectors for the plurality of receive antennas, one set for each receive antenna, wherein each set of channel response vectors is indicative of a channel response between the plurality of transmit antennas and one of the plurality of receive antennas;

computing a correlation matrix for each of the plurality of receive antennas based on the set of channel response vectors for the receive antenna; and

decomposing the correlation matrix for each receive antenna to obtain a steering vector for the receive antenna, wherein a plurality of steering vectors are obtained for the plurality of receive antennas and the plurality of steering vectors are used by the transmitting entity for spatial processing of at least one data stream sent to the receiving entity.

54. The method of claim 53, wherein the spatial processing is frequency-independent spatial processing.

55. The method of claim 53, wherein the computing the correlation matrix for each receive antenna includes:

computing a correlation matrix of each of the plurality of channel response vectors for the receive antenna to obtain a plurality of correlation matrices for the plurality of channel response vectors for the receive antenna, and summing the plurality of correlation matrices for the plurality of channel response vectors for the receive antenna to obtain the correlation matrix for the receive antenna.

56. The method of claim 53, further comprising:

deriving a matched filter for each of the plurality of receive antennas based on the steering vector and the set of channel response vectors for the receive antenna, filtering a received symbol stream for each of the plurality of receive antennas with the matched filter for the receive antenna to obtain a filtered symbol stream for the receive antenna; and

combining a plurality of filtered symbol streams forte plurality of receive antennas to obtain at least one detected symbol stream for the at least one data stream sent by the transmitting entity.

57. The method of claim 53, wherein one data stream is sent by the transmitting entity to the plurality of receive antennas using the plurality of steering vectors.

58. The method of claim 53, wherein a plurality of data streams are sent by the transmitting entity to the plurality of receive antennas using the plurality of steering vectors.

59. The method of claim 58, further comprising:

deriving a matched filter for each of the plurality of receive antennas based on the steering vector and the plurality of channel response vectors for the receive antenna, wherein a plurality of matched filters are derived for the plurality of receive antennas;

filtering a plurality of received symbol streams for the plurality of receive antennas with the plurality of matched filters to obtain a plurality of filtered symbol streams; and

combining the plurality of filtered symbol streams to obtain a plurality of detected symbol streams for the plurality of data streams sent by the transmitting entity.

60. The method of claim 59, further comprising:

performing space-time equalization on the plurality of detected symbol streams to obtain a plurality of recovered symbol streams for the plurality of data streams.

61. An apparatus in a wireless communication system with a plurality of transmit antennas at a transmitting entity and a plurality of receive antennas at a receiving entity, the apparatus comprising:

a channel estimator configured to obtain a plurality of sets of channel response vectors for the plurality of receive antennas, one set for each receive antenna, wherein each set of channel response vectors is indicative of a channel response between the plurality of transmit antennas and one of the plurality of receive antennas; and

a controller configured to compute a correlation matrix for each of the plurality of receive antennas based on the set of channel response vectors for the receive antenna and to decompose the single correlation matrix for each receive antenna to obtain a steering vector for the receive antenna, wherein a plurality of steering vectors are obtained for the plurality of receive antennas and the plurality of steering vectors are used by the transmitting entity for spatial processing of at least one data stream sent to the receiving entity.

62. The apparatus of claim 61, wherein the spatial processing is frequency-independent spatial processing.

63. The apparatus of claim 61, wherein the controller is configured to compute a correlation matrix of each of the plurality of channel response vectors for each receive antenna to obtain a plurality of correlation matrices for the plurality of channel response vectors for the receive antenna and to sum the plurality of correlation matrices for the plurality of channel response vectors for the receive antenna to obtain the correlation matrix for the respective receive antenna.

64. The apparatus of claim 61, wherein the controller is configured to derive a matched filter for each of the plurality of receive antennas based on the steering vector and the set of channel response vectors for the respective receive antenna.

65. The apparatus of claim 64, further comprising:

a plurality of matched filters for the plurality of receive antennas, one matched filter for each receive antenna, each matched filter is configured to filter a received symbol stream for the associated receive antenna to obtain a filtered symbol stream; and

a combiner configured to combine a plurality of filtered symbol streams from the plurality of matched filters to obtain at least one detected symbol stream for the at least one data stream sent by the transmitting entity.

66. An apparatus in a wireless communications system, comprising:

means for obtaining a plurality of sets of channel response vectors for a plurality of receive antennas, one set for each receive antenna, wherein each set of channel response vectors is indicative of a channel response between a plurality of transmit antennas and one of the plurality of receive antennas;

means for computing a correlation matrix for each of the plurality of receive antennas based on the set of channel response vectors for the respective receive antenna; and

means for decomposing the single correlation matrix for each receive antenna to obtain a steering vector for the respective receive antenna, wherein a plurality of steering vectors are obtained for the plurality of receive antennas and are used by a transmitting entity for spatial processing of at least one data stream sent to a receiving entity.

67. The apparatus of claim 66, wherein the spatial processing is frequency-independent spatial processing.

68. The apparatus of claim 66, further comprising:

means for computing a correlation matrix of each of the plurality of channel response vectors for each receive antenna to obtain a plurality of correlation matrices for the plurality of channel response vectors for the receive antenna; and

means for summing the plurality of correlation matrices for the plurality of channel response vectors for each receive antenna to obtain the correlation matrix for the respective receive antenna.

69. The apparatus of claim 66, further comprising:

means for deriving a matched filter for each of the plurality of receive antennas based on the steering vector and the set of channel response vectors for the respective receive antenna;

means for filtering a received symbol steam for each of the plurality of receive antennas with the matched fiber for the receive antenna to obtain a filtered symbol stream for the respective receive antenna; and

means for combining a plurality of filtered symbol streams for the plurality of receive antennas to obtain at least one detected symbol stream for the at least one data stream sent by the transmitting entity.

70. A computer-readable media for storing instructions operable to:

receive a plurality of sets of channel response vectors for a plurality of receive antennas, one set for each receive antenna, wherein each set of channel response vectors is indicative of a channel response between a plurality of transmit antennas and one of the plurality of receive antennas;

compute a correlation matrix for each of the plurality of receive antennas based on the set of channel response vectors for the respective receive antenna; and

decompose the correlation matrix for each receive antenna to obtain a steering vector for the respective receive antenna, wherein a plurality of steering vectors are obtained for the plurality of receive antenna and are used by a transmitting entity for spatial processing of at least one data stream sent to a receiving entity.

71. The processor readable media of claim 70, wherein the spatial processing is frequency-independent spatial processing.

72. The processor readable media of claim 70 and further storing instructions operable to:

compute a correlation matrix of each of the plurality of channel response vectors for each receive antenna to obtain a plurality of correlation matrices for the plurality of channel response vectors for the respective receive antenna; and

sum the plurality of correlation matrices for the plurality of channel response vectors for each receive, antenna to obtain the correlation matrix for the respective receive antenna.

73. The processor readable media of claim 70 and further storing instructions operable to:

derive a matched filter for each of the plurality of receive antennas based on the steering vector and the set of channel response vectors for the respective receive antenna;

filter a received symbol stream for each of the plurality of receive antennas with the matched filter for the receive antenna to obtain a filtered symbol stream for the respective receive antenna; and

combine a plurality of filtered symbol streams for the plurality of receive antennas to obtain at least one detected symbol stream for the at least one data stream sent by the transmitting entity.

74. A method of performing spatial processing in a multiple-input single-output (MISO) system utilizing orthogonal frequency division multiplexing (OFDM), the method comprising:

obtaining a set of channel response vectors indicative of a channel response between a plurality of transmit antennas at a transmitting entity and a receive antenna at a receiving entity in the MISO system;

computing a correlation matrix based on the set of channel response vectors; and

decomposing the correlation matrix to obtain steering information used by the transmitting entity for spatial processing of a data stream sent to the receiving entity.

75. The method of claim 74, wherein the wireless communication system is a multiple-input single-output (MISO) communication system.

76. The method of claim 74, wherein the steering information includes at least one steering vector.

77. The method of claim 74, wherein the spatial processing is frequency-independent spatial processing.

78. The method of claim 74, wherein the spatial processing is performed by the transmitting entity in the dine-domain on a stream of time-domain chips generated for the data stream by OFDM modulation.

79. The method of claim 74, wherein the spatial processing is performed by the transmitting entity in the frequency-domain for each of a plurality of subbands on data symbols generated for the data stream.

80. The method of claim 74, further comprising:

deriving a matched filter based on the steering information and the set of channel response vectors; and

filtering a received symbol stream with the matched filter to obtain a detected symbol stream.