Transmitter diversity technique for wireless communications
First Claim
1. An electronic circuit for receiving a wireless communication from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the electronic circuit comprising:
- a channel estimator for generating estimated transmit channel characteristics of transmit channels over which the communication from the first and second space diverse antennas are communicated to the electronic circuit and outputting said estimated transmit channel characteristics to a signal combiner and to a detector;
said signal combiner for combining signals received from said first and second space diverse antennas and outputting combined signals to said detector as two output data signals responsive to said estimated transmit channel characteristics; and
said detector for detecting respective transmitted signals in the presence of noise responsive to said estimated transmit channel characteristics and in accordance with a decision rule.
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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.
127 Citations
33 Claims
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1. An electronic circuit for receiving a wireless communication from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the electronic circuit comprising:
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a channel estimator for generating estimated transmit channel characteristics of transmit channels over which the communication from the first and second space diverse antennas are communicated to the electronic circuit and outputting said estimated transmit channel characteristics to a signal combiner and to a detector; said signal combiner for combining signals received from said first and second space diverse antennas and outputting combined signals to said detector as two output data signals responsive to said estimated transmit channel characteristics; and said detector for detecting respective transmitted signals in the presence of noise responsive to said estimated transmit channel characteristics and in accordance with a decision rule. - View Dependent Claims (2, 3, 4)
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5. 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:
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estimating channel characteristics of transmit channels over which the wireless communication from the first and second space diverse antennas are communicated and outputting estimated channel characteristics to a signal combiner and a detector using a decision rule; combining signals received from said first and second space diverse antennas and outputting 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 and being responsive to said estimated channel characteristics. - View Dependent Claims (6, 7)
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8. An electronic circuit for decoding wireless communication signals, comprising:
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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 antennae, wherein the combiner is configured to combine the received encoded symbols, and wherein the received encoded symbols include negated selected symbols and conjugated selected symbols; and a detector configured to recover said one of a time diverse or a frequency diverse signal responsive to said combiner, the detector receiving the combined encoded signals and recovering a transmitted signal for feedback to said combiner. - View Dependent Claims (9, 10)
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11. An electronic circuit for decoding wireless communication signals, comprising:
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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 to output first and second signals, and wherein the received encoded symbols include negated selected symbols and conjugated selected symbols; and a detector configured to recover one of a time diverse or a frequency diverse signal responsive to said combiner, the detector receiving the first and second output signals of said combiner and recovering a transmitted signal using one of a metric or decision rule. - View Dependent Claims (12, 13)
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14. An electronic circuit for receiving wireless communications of unequal power from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the electronic circuit comprising:
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a channel estimator for estimating characteristics of at least two transmit channels over which said wireless communications are received from said space diverse antennas and outputting estimated channel characteristics to a signal combiner and a detector; said signal combiner for combining signals received from said firs and second space diverse antennas and outputting combined signals to said detector as two output data signals is responsive to said estimated channel characteristics; and said detector for detecting respective transmitted signals in the presence of noise responsive to said estimated channel characteristics, said detector for feeding back the detected transmitted signals to said channel estimator. - View Dependent Claims (15)
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16. A method of receiving a wire less communication from first and second space diverse antennas, the wireless communication comprising symbols of unequal power, the wireless communication being transmitted over first and second sequential time intervals, the method comprising:
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combining signals received from said first and second space diverse antennas using a signal combiner and outputting said combined signals to a detector as two output data signals; estimating characteristics of a detected transmit channel and outputting estimated characteristics to said signal combiner and to said detector, the characteristics being related to a time difference between sequential transmissions from said space diverse antennas; and detecting respective transmitted signals in the presence of noise via said detector responsive to said estimated characteristics to recover the transmitted signals; and
feeding back the recovered transmitted signals for updating said estimated characteristics. - View Dependent Claims (17, 18)
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19. An electronic circuit for receiving a wireless communication transmitted from first and second space diverse transmit antennas, the wireless communication being further one of time diverse or frequency diverse, the electronic circuit comprising:
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first and second channel estimators for receiving said wireless communication via first and second space diverse receive antennas respectively and for estimating characteristics of transmit channels over which said wireless communication is received from said space diverse transmit antennas and outputting 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; said signal combiner for combining signals received from said first and second space diverse antennas and outputting combined signals to said detector as two output data signals responsive to said estimated characteristics; and said detector for recovering respective transmitted signals in the presence of noise responsive to said estimated characteristics and said two output data signals received from said signal combiner. - View Dependent Claims (20)
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21. A method of receiving a wireless communication transmitted from first and second space diverse antennas, the wireless communication being further one of time diverse or frequency diverse, the method comprising:
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receiving said wireless communication via first and second space diverse receive antennae at first and second channel estimators respectively; estimating characteristics of transmit channels over which said wireless communication is received from said first and second space diverse antennas at said first and second channel estimators and outputting 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 combined signals to said detector as two output data signals responsive to said estimated characteristics; and recovering respective transmitted signals at said detector in the presence of noise responsive to said estimated characteristics and said two output data signals. - View Dependent Claims (22)
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23. A method of receiving a wireless communication that includes a transmitted block of symbols transmitted from first and second space diverse antennas to a receiving device, comprising:
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receiving the transmitted block of symbols at the receiving device over respective first and second transmit channels that couple the first and second space diverse antennas to the receiving device, the transmitted block including symbols s0, s1, −
si*, and s0*, where * represents complex conjugation, the symbols s0 and s1 being space diverse with respect to each other and the symbols −
s1* and s0* being space diverse with respect to each other and the symbols s1 and s0* being orthogonal with respect to each other and the symbols s0 and −
s1* being orthogonal with respect to each other;estimating channel transfer characteristics of the transmit channels and outputting estimated channel transfer characteristics to a signal combiner; and combining the received transmitted block of symbols and supplying output signals in accordance with said estimated channel transfer characteristics. - View Dependent Claims (24, 25, 26, 27)
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28. A receiving device for receiving a wireless communication that includes a transmitted block of symbols transmitted from first and second space diverse antennas to the receiving device, the receiving device comprising:
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a channel estimator coupled to receive signals transmitted over respective first and second transmit channels that couple the first and second space diverse antennas to the receiving device, the channel estimator configured to generate estimated transmit channel characteristics of the first and second transmit channels and supply said estimated transmit channel characteristics to a signal combiner; and said signal combiner coupled to receive signals corresponding to the transmitted block of symbols, the transmitted block of symbols including symbols s0, s1, −
s1*, and s0*, where * represents complex conjugation, the symbols s0 and s1 being space diverse with respect to each other, the symbols −
s1* and s0* being space diverse with respect to each other, the symbols s1 and s0* being orthogonal with respect to each other, and the symbols s0 and −
s1* being orthogonal with respect to each other, the signal combiner configured to combine the received signals and output combined signals as output signals responsive to said estimated transmit channel characteristics. - View Dependent Claims (29, 30, 31, 32)
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33. A receiver comprising:
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a combiner responsive to signals received by an antenna and to channel estimates developed for at least two concurrent space diverse paths over which said signals arrive at said antenna, for developing sets of information symbol estimates, where said combiner develops said sets of information symbol estimates by combining said signals received by said antenna with said channel estimates via operations that involve multiplications, negations, and conjugations; a channel estimator responsive to said signals received by said antenna for developing said channel estimates; where said signal received by said antenna at a given time interval corresponds to r(t)=h0si+h1sj+n(t), and in a next time interval corresponds to r(t+T)=−
h0sj*+h1si*+n(t+T), where h0 is a transfer function of a channel over which a symbol si is transmitted at said given time, h1 is a transfer function of a channel over which a symbol sj is transmitted at said given time interval, n(t) and n(t+T) are noise signals at said given time interval and said next time interval, respectively, and * appended to a signal designation represents the complex conjugate of the signal; andwherein said combiner forms a set of information symbol estimates comprising symbols {tilde over (s)}i and {tilde over (s)}j by forming signals {tilde over (s)}i={tilde over (h)}0*r(t)+{tilde over (h)}1r*(t+T) and {tilde over (s)}j={tilde over (h)}1*r(t)−
{tilde over (h)}0r*(t+T) where {tilde over (h)}i is the estimate of the channel transfer function hi.
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Specification