Channel estimation using frequency smoothing
First Claim
1. A method of transmitting a training signal, the method comprising:
- generating a training signal in a quadrature modulation transmitter, the training signal representing a plurality of reference complex values to be respectively transmitted on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values to be respectively transmitted on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and
transmitting the training signal within the single symbol period.
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Abstract
A system and method are provided for supplying a frequency-smoothed communications training signal. The method generates a frequency-smoothed unbiased training signal in a quadrature modulation transmitter. The frequency-smoothed unbiased training signal includes a plurality of pilot signal products, where each pilot signal product includes complex plane information represented by a reference frequency subcarrier, multiplying complex plane information represented by mirror frequency subcarrier. The sum of the plurality of pilot signal products is equal to zero. The method supplies the frequency-smoothed unbiased training signal so that it may be transmitted within a single symbol period. System and methods are also provided for using a frequency-smoothed training signal in the calculation of a receiver channel estimate.
76 Citations
58 Claims
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1. A method of transmitting a training signal, the method comprising:
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generating a training signal in a quadrature modulation transmitter, the training signal representing a plurality of reference complex values to be respectively transmitted on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values to be respectively transmitted on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and transmitting the training signal within the single symbol period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for calculating a channel estimate, the method comprising:
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receiving a training signal at a quadrature demodulation receiver, the training signal representing a plurality of reference complex values respectively received on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values respectively received on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; generating a plurality of processed symbols (y) representing complex plane information based on the training signal; multiplying each processed symbol (y) by a conjugate of a corresponding reference complex value (p*); and obtaining a channel estimate (h) based on multiplication products. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for transmitting a training signal, the system comprising:
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a signal generator configured to generate a training signal representing a plurality of reference complex values to be respectively transmitted on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values to be respectively transmitted on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and a transmitter configured to transmit the training signal within the single symbol period. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A system for calculating a channel estimate using a frequency-smoothed unbiased training signal, the system comprising:
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a receiver configured to receive a training signal representing a plurality of reference complex values respectively received on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values respectively received on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and a processor configured to generate a plurality of processed symbols (y) representing complex plane information based on the training signal, multiply each processed symbol (y) by a conjugate of a corresponding reference signal (p*), and determine a channel estimate (h) based on the multiplication products. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36)
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37. A non-transitory machine-readable medium having stored thereon instructions for transmitting a training signal, the instructions comprising:
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generating a training signal in a quadrature modulation transmitter, the training signal representing a plurality of reference complex values to be respectively transmitted on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values to be respectively transmitted on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and transmitting the training signal within the single symbol period.
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38. A non-transitory machine-readable medium having stored thereon instructions for calculating a channel estimate, the instructions comprising:
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receiving a training signal at a quadrature demodulation receiver, the training signal representing a plurality of reference complex values respectively received on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values respectively received on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; generating a plurality of processed symbols (y) representing complex plane information based on the training signal; multiplying each processed symbol (y) by a conjugate of a corresponding reference complex value (p*); and obtaining a channel estimate (h) based on multiplication products.
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39. A device for transmitting a training signal, the device comprising:
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signal generation means for generating a training signal representing a plurality of reference complex values to be respectively transmitted on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values to be respectively transmitted on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and transmitting means for transmitting the training signal within the single symbol period. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47)
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48. A device for calculating a channel estimate, the device comprising:
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receiving means for receiving a training signal representing a plurality of reference complex values respectively received on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values respectively received on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and processing means for generating a plurality of processed symbols (y) representing complex plane information based on the training signal, multiplying each processed symbol (y) by a conjugate of a corresponding reference signal (p*), and determining a channel estimate (h) based on the multiplication products. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55, 56)
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57. A processing device for generating a frequency-smoothed unbiased training signal, the processing device comprising:
a processor to generate a training signal representing a plurality of reference complex values to be respectively transmitted on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values to be respectively transmitted on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero.
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58. A processing device for calculating a channel estimate, the processing device comprising:
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a receiver to receive a training signal representing a plurality of reference complex values respectively received on a plurality of reference frequency subcarriers during a single symbol period and a plurality of corresponding mirror complex values respectively received on a plurality of corresponding mirror frequency subcarriers during the single symbol period, wherein the sum of the products of the reference complex values and the corresponding mirror complex values is equal to zero; and a processor configured to generate a plurality of processed symbols (y) representing complex plane information based on the training signal, multiply each processed symbol (y) by a conjugate of a corresponding reference signal (p*), and determine a channel estimate (h) based on the multiplication products.
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Specification