High-speed decoder for a multi-pair gigabit transceiver
First Claim
1. A method for providing an input signal to a symbol decoder, the input signal being based on a tail value and a subset of coefficient values received from a single decision feedback equalizer, the method comprising the operations of:
- (a) generating a set of pre-computed values in a multiple decision feedback equalizer, the pre-computed values being based on the subset of coefficient values received from the single decision feedback equalizer;
(b) combining each of the pre-computed values with the tail value to generate a tentative sample; and
(c) selecting one of the tentative samples as the input signal to the symbol decoder.
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Abstract
A method and a system for providing an input signal from a multiple decision feedback equalizer to a decoder based on a tail value and a subset of coefficient values received from a decision-feedback equalizer. A set of pre-computed values based on the subset of coefficient values is generated. Each of the pre-computed values is combined with the tail value to generate a tentative sample. One of the tentative samples is selected as the input signal to the decoder. In one aspect of the system, tentative samples are saturated and then stored in a set of registers before being outputted to a multiplexer which selects one of the tentative samples as the input signal to the decoder. This operation of storing the tentative samples in the registers before providing the tentative samples to the multiplexer facilitates high-speed operation by breaking up a critical path of computations into substantially balanced first and second portions, the first portion including computations in the decision-feedback equalizer and the multiple decision feedback equalizer, the second portion including computations in the decoder.
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Citations
47 Claims
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1. A method for providing an input signal to a symbol decoder, the input signal being based on a tail value and a subset of coefficient values received from a single decision feedback equalizer, the method comprising the operations of:
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(a) generating a set of pre-computed values in a multiple decision feedback equalizer, the pre-computed values being based on the subset of coefficient values received from the single decision feedback equalizer; (b) combining each of the pre-computed values with the tail value to generate a tentative sample; and (c) selecting one of the tentative samples as the input signal to the symbol decoder. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A multiple decision feedback equalizer for providing an input signal to a decoder, the multiple decision feedback equalizer receiving a tail value and a subset of coefficient values from a single decision-feedback equalizer, the multiple decision feedback equalizer comprising:
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(a) a computing module for generating a set of precomputed values based on the subset of coefficient values received from the single decision feedback equalizer; (b) a set of adders coupled-to the computing module, the adders corresponding one-to-one to the pre-computed values, each of the adders combining the corresponding precomputed value with the tail value to generate a tentative sample; and (c) a multiplexer coupled to the adders, the multiplexer receiving the tentative samples, selecting and outputting one of the tentative samples as the input signal to the decoder. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for decoding an input sample into a final decision corresponding to a codeword of a trellis code having N states, the method comprising the operations of:
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(a) decoding a set of signal samples to generate tentative decisions and the final decision using a decoder block; (b) providing the tentative decisions to a single decision-feedback equalizer, the single decision feedback equalizer having a set of low-ordered coefficients and a set of high-ordered coefficients; (c) generating from the single decision-feedback equalizer a tail value based on the tentative decisions, values of the high-ordered coefficients and the input sample; (d) providing the tail value and values of the low ordered coefficients to a multiple decision feedback equalizer; and (e) generating from the multiple decision feedback equalizer the set of signal samples for the decoder. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A decision-feedback sequence estimation block for decoding an input sample into a final decision corresponding to a codeword of a trellis code having N states, the decision-feedback sequence estimation block comprising:
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(a) a decoder block decoding a set of signal samples to generate tentative decisions and the final decision; (b) a single decision-feedback equalizer coupled to the decoder block for receiving the tentative decisions, the decision feedback equalizer having a set of low-ordered coefficients and a set of high-ordered coefficients, the single decision-feedback equalizer generating a tail value based on the tentative decisions, values of the high-ordered coefficients and the input sample; and (c) a multiple decision feedback equalizer coupled to the single decision-feedback equalizer for receiving the tail value and values of the low-ordered coefficients, the multiple decision feedback equalizer generating the set of signal samples for the decoder block. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A receiver for demodulating a received signal, the received signal resulting from information signals being encoded in accordance with a multi-state encoding scheme and modulated in accordance with a multi-level modulation alphabet before transmission, the receiver comprising:
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a symbol decoder receiving a set of ISI compensated signal samples representing the received signal and corresponding to the plurality of states of the encoding scheme, the symbol decoder evaluating the signal samples in accordance with the multi-level modulation alphabet, wherein the symbol decoder comprises a symbol detector receiving the set of ISI compensated signal samples and computing path metrics for each of the states of the multi-state encoding scheme and outputting decisions based on the path metrics; decoding the evaluated signal samples in accordance with the multi-state encoding scheme, and outputting tentative decisions; and an ISI compensation circuit coupled to the symbol decoder to receive the tentative decisions, the ISI compensation circuit comprising a single decision feedback equalizer, the single decision feedback equalizer providing an ISI compensation to the received signal based on tentative decisions and providing the set of ISI compensated signal samples to the symbol decoder. - View Dependent Claims (38, 39, 40, 41)
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42. A method for ISI compensating and decoding a received signal, the received signal resulting from information signals being encoded in accordance with a multi-state encoding scheme and modulated in accordance with a multi-level modulation alphabet before transmission, the method comprising the operations of:
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receiving a set of ISI compensated signal samples representing the received signal with ISI substantially cancelled; evaluating the ISI compensated signal samples in accordance with the multi-level modulation alphabet and with the multi-state encoding scheme in a symbol decoder; outputting tentative decisions from the symbol decoder; generating the ISI compensated signal samples from the received signal and the tentative decisions using a single decision feedback equalizer; and providing the ISI compensated signal samples to the symbol decoder, wherein the single decision feedback equalizer includes a set of low-ordered coefficients and a set of high-ordered coefficients, and wherein the operation of generating the ISI compensated signal samples comprises; combining the tentative decisions with values of the set of high-ordered coefficients to produce a partial ISI component; and combining the partial ISI component with the received signal to generate a partially ISI compensated intermediate signal, wherein the operation of generating the ISI compensated signal samples further comprises; combining the values of the low-ordered coefficients with a set of values representing levels of the multi-level modulation alphabet to generate a plurality of convolution result terms; and combining the partially ISI compensated intermediate signal with each of the plurality of convolution result terms to produce a set of potential signal samples for each of a plurality of states of the multi-state encoding scheme, the sets of potential signal samples corresponding one-to-one to the states of the multi-state encoding scheme. - View Dependent Claims (43, 44, 45, 46, 47)
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Specification