System and method for time-domain equalization in discrete multi-tone system
First Claim
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1. A time-domain equalizer system, comprising;
- QAM silicers for converting the output of FEQ to the corresponding signal in the QAM constellation for each subcarrier;
an IFFT for inverse fast Fourier transforming data generated by QAM slicers;
a Paraller/Serial converter (P/S) for converting said IFFT output data into a serial form;
a feedforward filter (FF) for whitening the received noises and producing an overall effective channel response such that the output only has causal components;
a feedback filter (FB) for reconstructing the residual causal ISI by using the past decisions;
a delay line for buffering the signals to the input of the feedback filter; and
a switch for connecting the input end of said delay line to a first node.
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Abstract
A novel structure for the TEQ in a DMT system receiver to shorten the length of the effective channel impulse response is provided. A time-domain equalizer, based on the decision-feedback filter structure, along with a training method is disclosed. In accordance with the DFE-based TEQ in the DMT system, the data symbols that transmitted through the effective shortened channel would be more reliable.
21 Citations
25 Claims
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1. A time-domain equalizer system, comprising;
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QAM silicers for converting the output of FEQ to the corresponding signal in the QAM constellation for each subcarrier;
an IFFT for inverse fast Fourier transforming data generated by QAM slicers;
a Paraller/Serial converter (P/S) for converting said IFFT output data into a serial form;
a feedforward filter (FF) for whitening the received noises and producing an overall effective channel response such that the output only has causal components;
a feedback filter (FB) for reconstructing the residual causal ISI by using the past decisions;
a delay line for buffering the signals to the input of the feedback filter; and
a switch for connecting the input end of said delay line to a first node. - View Dependent Claims (2, 3, 4)
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5. A time-domain equalizer system, comprising
a feedforward filter(FF) for whitening the received noises and producing an overall effective channel response such that the output only has causal components; -
a feedback filter(FB) for reconstructing the residual causal ISI by using the past decisions; and
a delay ling for buffering the signals to the input of the feedback filter.
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6. A training method of TEQ, comprising the steps
a) fixing the feedforward and feedback filters, and updating a TIR filter in a frequency domain; -
b) performing a windowing operation on said TIR in a time domain to limit the taps outside the window of length v+1 to be zero;
c) fixing said TIR and updating said feedforward and feedback filter in said frequency domain; and
d) performing said windowing operations on said feedforward and feedback filters in said time domain to limit them to only Na and Nb consecutive non-zero taps, respectively. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification