Method and arrangement for synchronization in OFDM modulation
First Claim
1. A method for synchronization in OFDM (orthogonal frequency division multiplexing) modulation, whereby frequency errors in an IF (intermediate frequency) clock and a sampling clock are controlled by estimating the deviation of the sampling clock and of the IF clock for two subcarriers with different frequencies (k1 and, respectively, k2), comprising:
- choosing the different frequencies (k1, k2) symmetrically around zero;
detecting absolute phase errors (θ
1, θ
2) for both subcarriers;
forming a timing error and a phase error from the absolute phase errors (θ
1, θ
2);
forming a first control signal (F1) from the deviation of the sampling clock and the timing error for controlling the sampling clock; and
forming a second control signal (F2) from the deviation of the IF clock and the phase error for controlling the IF clock.
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Abstract
A method and an arrangement for synchronization in OFDM modulation. Frequency errors of an IF clock and a sampling clock are controlled by estimating the deviation of the sampling clock and, respectively, the IF clock for two subcarriers with different frequencies. According to the invention, the frequencies are chosen symmetrically around zero and the absolute phase errors are detected for both subcarriers. Timing errors and phase errors are formed from the absolute phase errors in order to generate two control signals. The first control signal is formed from the deviation of the sampling clock and the timing error for controlling the sampling clock while the second control signal is formed from the deviation of the IF clock and the phase error for controlling the IF clock.
132 Citations
19 Claims
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1. A method for synchronization in OFDM (orthogonal frequency division multiplexing) modulation, whereby frequency errors in an IF (intermediate frequency) clock and a sampling clock are controlled by estimating the deviation of the sampling clock and of the IF clock for two subcarriers with different frequencies (k1 and, respectively, k2), comprising:
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choosing the different frequencies (k1, k2) symmetrically around zero; detecting absolute phase errors (θ
1, θ
2) for both subcarriers;forming a timing error and a phase error from the absolute phase errors (θ
1, θ
2);forming a first control signal (F1) from the deviation of the sampling clock and the timing error for controlling the sampling clock; and forming a second control signal (F2) from the deviation of the IF clock and the phase error for controlling the IF clock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An arrangement for synchronizing in OFDM modulation, comprising:
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a down converter for down conversion of an IF signal to baseband components; an oscillator with an IF clock, said oscillator controlling said down converter; an A/D (analog-to-digital) converter for digitization of the baseband components; an oscillator with a sampling clock, said oscillator with said sampling clock controlling said A/D converter; an FFT processor for converting the baseband components from the time domain to the frequency domain; a demultiplexing unit for forming two subcarriers with different frequencies; elements for forming a deviation of the sampling clock and a deviation of the IF clock; elements for forming absolute phase errors of the two subcarriers; elements for forming a timing error from the absolute phase errors; elements for forming a phase error from the absolute phase errors; elements for forming a first control signal (F1) from the deviation of the sampling clock and the timing error for controlling the sampling clock; and elements for forming a second control signal (F2) from the deviation of the IF clock and the phase error for controlling the IF clock. - View Dependent Claims (18, 19)
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Specification