Preamble design for frequency offset estimation and channel equalization in burst OFDM transmission system
First Claim
1. A method of estimating frequency offset in an orthogonal frequency division multiplexing system, the method comprising:
- calculating normalized frequency offset for each of a known experimental sample signal in which a correlative distance is the number N of subcarriers and a known experimental sample signal in which a correlative distance is two times 2N the number of subcarriers; and
subtracting or adding a predetermined value from or to normalized frequency offset calculated when the correlative distance is 2N, within a range of a normalized frequency offset value calculated when the correlative distance is N so as to estimate the frequency offset.
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Abstract
Provided is a transmission data frame in an orthogonal frequency division multiplexing (OFDM) burst mode transmission, and more particularly, a frequency offset estimating method and a channel equalizing method using a transmission data frame. In the transmission data frame used in the orthogonal frequency division multiplexing burst mode transmission, a length of a guard interval in a preamble area for frequency offset estimation and channel estimation varies depending on a channel environment not being limited in consideration of a size of a data symbol, and only data of ending part of the guard interval in the preamble is used to estimate frequency offset in consideration of intersymbol interference. In the frequency offset estimating method, desired frequency estimation efficiency can be satisfied with the small number of samples. Also, when channel equalization is performed, two symbols are averaged in a time area to reduce the accuracy of channel estimation due to Gaussian random noise. In a frequency area, by referring to weight placed on an adjacent subcarrier, a channel equalization coefficient is obtained to efficiently reduce Gaussian random noise.
70 Citations
31 Claims
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1. A method of estimating frequency offset in an orthogonal frequency division multiplexing system, the method comprising:
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calculating normalized frequency offset for each of a known experimental sample signal in which a correlative distance is the number N of subcarriers and a known experimental sample signal in which a correlative distance is two times 2N the number of subcarriers; and
subtracting or adding a predetermined value from or to normalized frequency offset calculated when the correlative distance is 2N, within a range of a normalized frequency offset value calculated when the correlative distance is N so as to estimate the frequency offset. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of equalizing a channel in an orthogonal frequency division multiplexing system, the method comprising:
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averaging two signals, which are transmitted in the same known pattern and received via a wireless channel, in a time area to obtain an average value; and
calculating a channel coefficient by performing fast Fourier transform for the obtained average value. - View Dependent Claims (9, 10, 11, 12)
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- 13. A transmission data frame structure used in an orthogonal frequency division multiplexing burst mode system, the transmission data frame structure in which a length of a guard interval in a preamble area for frequency offset estimation and channel estimation varies depending on a channel environment not being limited in consideration of a size of a data symbol, and only data of ending part of the guard interval in the preamble is used to estimate frequency offset in consideration of intersymbol interference.
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16. A computer-readable recording medium in which a program for executing a frequency offset estimating method performed in an orthogonal frequency division multiplexing system in a computer is recorded, the frequency offset estimating method comprising:
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calculating normalized frequency offset for each of a known experimental sample signal in which a correlative distance is the number N of subcarriers and a known experimental sample signal in which the correlative distance is two times 2N the number of subcarriers; and
subtracting or adding a predetermined value from or to the normalized frequency offset calculated when the correlative distance is 2N within a range of the normalized frequency offset calculated when the correlative distance is N so as to estimate normalized frequency offset.
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17. A computer-readable recording medium in which a program for executing a channel equalizing method performed in an orthogonal frequency division multiplexing system in a computer is recorded, the channel equalizing method comprising:
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averaging two signals, which are transmitted in the same known pattern and received via a wireless channel, in a time area to obtain an average value; and
calculating a channel coefficient by performing fast Fourier transform for the obtained average value.
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18. A computer-readable medium having stored thereon a data structure comprising:
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a first field containing data representing a calculating of normalized frequency offset for each of a known experimental sample signal in which a correlative distance is the number N of subcarriers and a known experimental sample signal in which the correlative distance is two times 2N the number of subcarriers; and
a second field containing data representing a changing of a predetermined value from the normalized frequency offset calculated when the correlative distance is 2N within a range of the normalized frequency offset calculated when the correlative distance is N accommodating to estimate normalized frequency offset. - View Dependent Claims (19)
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20. A method, comprising:
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calculating normalized frequency offset for each of a known experimental sample signal in which a correlative distance is the number N of subcarriers and a known experimental sample signal in which a correlative distance is two times 2N the number of subcarriers;
changing by a predetermined value of a normalized frequency offset calculated when the correlative distance is 2N, within a range of a normalized frequency offset value calculated when the correlative distance is N so as to estimate the frequency offset;
averaging two signals, which are transmitted in the same known pattern and received via a wireless channel, in a time area to obtain an average value; and
calculating a channel coefficient by performing fast Fourier transform for the obtained average value. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification