TRANSMITTER DIVERSITY TECHNIQUE FOR WIRELESS COMMUNICATIONS

• US 20070110179A1
• Filed: 09/28/2006
• Published: 05/17/2007
• Est. Priority Date: 09/16/1997
• Status: Active Grant

• Current Assignee: Cingular Wireless II LLC (AT&T, Inc.)
• Original Assignee: Cingular Wireless II LLC (AT&T, Inc.)
• Inventors: Alamouti, Siavash, Tarokh, Vahid
• Granted Patent: US 7,386,077 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 1/02 Transmitters
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/04 using frequency diversity
• CPC Class Codes: H04L 1/0606 Space-frequency coding
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: H04L 1/0643 block codes
• CPC Class Codes: H04L 1/0668 : Orthogonal systems, e.g. using Alamouti codes
• CPC Class Codes: H04L 1/08 : by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 25/0202 : Channel estimation

Abstract

A simple block coding arrangement is created with symbols transmitted over a plurality of transmit channels, in connection with coding that comprises only of simple arithmetic operations, such as negation and conjugation. The diversity created by the transmitter utilizes space diversity and either time or frequency diversity. Space diversity is effected by redundantly transmitting over a plurality of antennas, time diversity is effected by redundantly transmitting at different times, and frequency diversity is effected by redundantly transmitting at different frequencies. Illustratively, using two transmit antennas and a single receive antenna, one of the disclosed embodiments provides the same diversity gain as the maximal-ratio receiver combining (MRRC) scheme with one transmit antenna and two receive antennas. The principles of this invention are applicable to arrangements with more than two antennas, and an illustrative embodiment is disclosed using the same space block code with two transmit and two receive antennas.

Claims

1-21. -21. (canceled)

22. A method for transmitting over a transmission medium information corresponding to incoming symbols, comprising the steps of:

encoding said incoming symbols as blocks of n symbols to generate coded sequences of symbols, the generated code sequences selectively including one of selectively complex conjugating symbols and selectively negating and complex conjugating symbols; and

transmitting the coded sequences of symbols from at least two space diverse antennas, each of the at least two space diverse antennas transmitting a differently coded sequences, the transmission being further one of time diverse or frequency diverse.

24. The method of claim 22 where said encoding consists of replicating an incoming symbol, forming a complex conjugate of an incoming symbol, forming a negative of an incoming symbol or forming a negative complex conjugate of an incoming symbol.

38. A method for transmitting over a transmission medium information corresponding to incoming symbols as recited in claim 22, comprising transmitting an initial pair of signals known to a receiver.

23. (canceled)

25-37. -37. (canceled)

39. A method for transmitting over a transmission medium information corresponding to incoming symbols, comprising the steps of:

generating a first block of output symbols from the incoming symbols and a second block of output symbols related to the first block of output symbols, each one of the output symbols in the first block of output symbols being related, as a set of output symbols, with one of the output symbols in the second block of output symbols, one symbol in each set of symbols being the complex conjugate or a negative complex conjugate of the other symbol in the set of output symbols;

transmitting by first and second space diverse antennas, each space diverse antenna receiving respective first and second blocks of output symbols.

40. A method of transmitting information as recited in claim 39 wherein one of the output symbols in each set of symbols is transmitted with one of either time or frequency diversity from its related output symbol in the set of symbols.

41. A method of transmitting information as recited in claim 39 wherein a first symbol in each block of symbols is transmitted at time t and a second symbol in each block of symbols is transmitted at time t+T, where T is greater than zero.

42. A method of transmitting information as recited in claim 39 wherein the first and second blocks of output symbols are of equal energy.

43. A method of transmitting information as recited in claim 39 further comprising phase shift key modulating symbols for transmission.

44. A method of transmitting information as recited in claim 39 wherein two space diverse antennas transmit a symbol on one of said antennas and a related conjugate of said symbol on the other of said antennas within a given time interval.

45. A method for transmitting over a transmission medium information corresponding to incoming symbols as recited in claim 39, comprising transmitting an initial pair of signals known to a receiver.

46. A method for transmitting over a transmission medium information corresponding to incoming symbols, comprising the steps of:

receiving blocks of incoming symbols,

encoding the incoming symbols, the encoding including negation and complex conjugation of selected symbols;

transmitting the encoded symbols via at least two space diverse antennas, the transmitting also creating one of time diversity or frequency diversity.

47. A method of transmitting information as recited in claim 46, the transmitted encoded symbols being respectively applied in successive sequences of symbols of equal length to each antenna.

48. A method of transmitting information as recited in claim 46, the transmitted encoded symbols having equal energy.

49. A method of transmitting information as recited in claim 46 further comprising phase shift key modulating symbols for transmission.

50. A method of transmitting information as recited in claim 46 further comprising phase shift key modulating symbols for transmission.

51. A method of transmitting information as recited in claim 46 wherein two space diverse antennas transmit a symbol on one of said antennas and a related conjugate of said symbol on the other of said antennas within a given time interval.

52. A method for transmitting over a transmission medium information corresponding to incoming symbols as recited in claim 46, comprising transmitting an initial pair of signals known to a receiver.

53. A transmitter for wireless communications comprising:

a coder for receiving incoming data in blocks of symbols and generating coded sequences of symbols, the generated code sequences including complex conjugating symbols and negating and complex conjugating symbols,

at least two space diverse transmitting antennas for transmitting differently coded sequences.

54. A transmitter for wireless communication as recited in claim 53, the coder further creating one of time diversity or frequency diversity.

55. A transmitter as recited in claim 53, the transmitted encoded symbols being respectively applied in successive sequences of symbols of equal length to each antenna.

56. A transmitter as recited in claim 53, the transmitted encoded symbols having equal energy.

57. A transmitter as recited in claim 53 further comprising phase shift key modulating symbols for transmission.

58. A method for transmitting over a transmission medium information corresponding to incoming symbols, comprising the steps of:

encoding said incoming signals for transmission via first and second space diverse antennas as block code symbol sequences of symbols and the conjugates of said symbols over at least two symbol periods and

phase shift key modulating said symbol sequences for transmission.

59. A method for transmitting over a transmission medium information corresponding to incoming symbols as recited in claim 58, comprising transmitting an initial pair of signals known to a receiver.

60. A wireless transmitter for transmitting encoded information comprising

an encoder for encoding incoming signals for transmission as block code symbol sequences of symbols and the conjugates of said symbols over at least two symbol periods, the encoder including phase shift key modulation and

at least two first and second space diverse antennas coupled to said encoder for transmitting the symbols and their conjugates over at least two symbol periods.

61. A method of receiving a wireless communication from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the method comprising the steps of

estimating characteristics of a transmit channel received from said space diverse antennas and outputting said estimated characteristics to a signal combiner and a maximum likelihood detector, the characteristics being related to a time difference between sequential transmissions from said space diverse antennas;

combining signals received from said first and second space diverse antennas and outputting said combined signals to said maximum likelihood detector as two output data signals responsive to said estimated channel characteristics;

and detecting respective transmitted signals in the presence of noise via said maximum likelihood detector responsive to said estimated channel characteristics.

62. A method of receiving a wireless communication as recited in claim 61, comprising initially receiving a known transmitted signal.

63. A method of receiving a wireless communication as recited in claim 61, comprising feeding back the detected transmitted signals.

64. A method of receiving a wireless communication from first and second space diverse antennas, the wireless communication comprising first, second and third transmitted signals, the method comprising

combining first and second transmitted signals and noise to develop a first received signal and combining first and second conjugate transmitted signals and noise to develop a second received signal,

developing estimates of the first and second transmitted signals and applying said estimates to a maximum likelihood detector;

recovering said first and second transmitted signals for combining with further received signals to recover third and fourth transmitted signals.

65. A method of receiving a wireless communication as recited in claim 64 comprising initially receiving a known transmitted signal.

66. A method of receiving a wireless communication as recited in claim 64 comprising feeding back the detected transmitted signals.

67. An electronic circuit for decoding wireless communication signals, comprising:

a combiner adapted to receive one of an incoming time diverse or frequency diverse signal representing blocks of encoded symbols, wherein the blocks of symbols have been transmitted by a plurality of spatially diverse antennas, wherein the combiner is configured to combine the received encoded symbols, and wherein the received encoded symbols include negating selected symbols and conjugating selected symbols, and

a maximum likelihood detector configured to receive one of a time diverse or a frequency diverse signal, the detector receiving the combined encoded signals and recovering a transmitted signal using a channel transfer function.

68. An electronic circuit as recited in claim 67, the combiner initially receiving a known transmitted signal.

69. An electronic circuit as recited in claim 67, the maximum likelihood detector feeding back the recovered transmitted signals.

70. A method of receiving a wireless communication from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the method comprising the steps of

estimating characteristics of a transmit channel received from said space diverse antennas and outputting said estimated characteristics to a signal combiner and a detector using a decision rule, the characteristics being related to a time difference between sequential transmissions from said space diverse antennas;

combining signals received from said first and second space diverse antennas and outputting said combined signals to said detector as two output data signals responsive to said estimated channel characteristics;

and detecting respective transmitted signals in the presence of noise via said detector using said decision rule responsive to said estimated channel characteristics.

71. A method of receiving a wireless communication from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the method comprising the steps of

estimating characteristics of a transmit channel received from said space diverse antennas and outputting said estimated characteristics to a signal combiner and a detector, the characteristics being related to a time difference between sequential transmissions from said space diverse antennas;

combining signals received from said first and second space diverse antennas and outputting said combined signals to said detector as two output data signals responsive to said estimated channel characteristics;

and detecting respective transmitted signals in the presence of noise via said detector responsive to said estimated channel characteristics.

72. A method of receiving a wireless communication as recited in claim 71, comprising initially receiving a known transmitted signal.

73. A method of receiving a wireless communication as recited in claim 71, comprising feeding back the detected transmitted signals.

74. A method of receiving a wireless communication from first and second space diverse antennas, the wireless communication comprising first, second and third transmitted signals, the method comprising

combining first and second transmitted signals and noise to develop a first received signal and combining first and second conjugate transmitted signals and noise to develop a second received signal,

developing estimates of the first and second transmitted signals and applying said estimates to a decoder using a decision rule;

recovering said first and second transmitted signals for combining with further received signals to recover third and fourth transmitted signals.

75. A method of receiving a wireless communication as recited in claim 74 comprising initially receiving a known transmitted signal.

76. A method of receiving a wireless communication as recited in claim 74 comprising feeding back the detected transmitted signals.

77. An electronic circuit for decoding wireless communication signals, comprising:

a combiner adapted to receive one of an incoming time diverse or frequency diverse signal representing blocks of encoded symbols, wherein the blocks of symbols have been transmitted by a plurality of spatially diverse antennas, wherein the combiner is configured to combine the received encoded symbols, and wherein the received encoded symbols include negating selected symbols and conjugating selected symbols, and

a detector configured to receive one of a time diverse or a frequency diverse signal, the detector receiving the combined encoded signals and recovering a transmitted signal using a channel transfer function.

78. An electronic circuit as recited in claim 77, the combiner initially receiving a known transmitted signal.

79. An electronic circuit as recited in claim 77, the detector feeding back the recovered transmitted signals.

80. An electronic circuit as recited in claim 77, the channel transfer function being multiplied times a transmitted symbol.