Estimator having a feedback loop
First Claim
1. A signal estimation loop for generating an estimated signal from an input signal in each symbol period, the input signal being received through a channel having an impulse response including a postcursor component for a plurality of symbols, the signal estimation loop comprising:
- a subtracter for subtracting a postcursor estimation signal from the input signal to produce a difference signal which is used to generate the estimated signal;
a postcursor estimator for generating all possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on a post estimated signal in a second past symbol period which is at least two symbols earlier; and
a selector for selecting one of the possible postcursor estimation signals based on the estimated signal to output a selected one as the postcursor estimation signal to the subtracter in the symbol period.
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Abstract
A signal estimation loop includes a postcursor estimator which generates all possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on a past estimated signal in a second past symbol period which is at least two symbols earlier. One of the possible postcursor estimation signals is selected based on the estimated signal to output a postcursor estimation signal to a subtracter in the symbol period. The subtracter subtracts the postcursor estimation signal from an input signal to produce a difference signal which is used to generate the estimated signal.
40 Citations
18 Claims
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1. A signal estimation loop for generating an estimated signal from an input signal in each symbol period, the input signal being received through a channel having an impulse response including a postcursor component for a plurality of symbols, the signal estimation loop comprising:
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a subtracter for subtracting a postcursor estimation signal from the input signal to produce a difference signal which is used to generate the estimated signal; a postcursor estimator for generating all possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on a post estimated signal in a second past symbol period which is at least two symbols earlier; and a selector for selecting one of the possible postcursor estimation signals based on the estimated signal to output a selected one as the postcursor estimation signal to the subtracter in the symbol period. - View Dependent Claims (2)
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3. A signal estimator for generating an estimated signal from an input signal in each symbol period, the input signal being received through a channel having an impulse response including a precursor component for N symbols and a postcursor component for M symbols, where N and M are an integer, the signal estimator comprising:
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a first subtracter for subtracting the precursor component from the input signal to produce a first difference signal; a delay memory for storing the first difference signal to delay one symbol; and a feedback loop for generating the estimated signal from the first difference signal received from the delay memory in each symbol period, the feedback loop comprising; a second subtracter for subtracting the first difference signal depending on a postcursor estimation signal to produce a second difference signal which is used to generate the estimated signal; a postcursor estimator for generating all possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on a past estimated signal in a second past symbol period which is at least two symbols earlier; and a selector for selecting one of the possible postcursor estimation signals based on the estimated signal to output a selected one as the postcursor estimation signal to the second subtracter in the symbol period. - View Dependent Claims (4, 5, 6)
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7. A signal estimation loop for estimating a received signal according to Viterbi algorithm, the received signal having K values (K is an integer greater than 1) and being subjected to distortion due to a channel having an impulse response including a precursor component for N symbols, a center component and a postcursor component for M symbols, where N and M are an integer, the signal estimation loop comprising:
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a subtracter for subtracting KN+1 postcursor estimation signals from the received signal to produce KN+1 difference signals, respectively, the KN+1 postcursor estimation signals being obtained by repeatedly using 2M postcursor estimation signals; a branch metric generator for generating KN+1 branch metrics from the KN+1 difference signals, respectively; a path selector for selecting 2N survivor paths from possible paths obtained based on the KN-1 branch metrics to produce 2N path selection signals each indicating which path is selected; a decision processor for generating 2N estimated signals for M symbols from the 2N path selection signals; a postcursor estimator for generating KN+1 possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on 2N past estimated signals in a second past symbol period which is at least two symbols earlier; and a postcursor estimation selector for selecting the 2N postcursor estimation signals from the KN+1 possible postcursor estimation signals according to the 2N path selection signals to output the 2N postcursor estimation signals to the subtracter. - View Dependent Claims (8, 9, 10)
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11. A signal estimator for estimating a received signal according to Viterbi algorithm, the received signal having K values (K is an integer greater than 1) and being subjected to distortion due to a channel having an impulse response including a precursor component for N symbols, a center component and a postcursor component for M symbols, where N and M are an integer, the signal estimator comprising:
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an precursor subtracter for subtracting KN+1 precursor estimation signals from the received signal to produce KN+1 first difference signals, the KN+1 precursor estimation signals being generated based on the precursor component for N symbols and the center component; a delay memory for storing the KN+1 first difference signals to delay one symbol, respectively; and a feedback loop for generating 2N estimated signals from the KN+1 first difference signals received from the delay memory in each symbol period, the feedback loop comprising; a subtracter for subtracting KN+1 postcursor estimation signals from the KN+1 first difference signal to produce KN+1 second difference signals, respectively, the KN+1 postcursor estimation signals being obtained by repeatedly using 2N postcursor estimation signals; a branch metric generator for generating KN+1 branch metrics from the KN+1 second difference signals, respectively; a path selector for selecting 2N survivor paths from possible paths obtained based on the KN+1 branch metrics to produce 2N path selection signals each indicating which path is selected; a decision processor for generating 2N estimated signals for M symbols from the 2N path selection signals; a postcursor estimator for generating KN+1 possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on 2N past estimated signals in a second past symbol period which is at least two symbols earlier; and a postcursor estimation selector for selecting the 2N postcursor estimation signals from the KN+1 possible postcursor estimation signals according to the 2N path selection signals to output the 2N postcursor estimation signals to the subtracter. - View Dependent Claims (12, 13, 14)
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15. A signal estimation method for generating an estimated signal from an input signal in each symbol period, the input signal being received through a channel having an impulse response including a postcursor component for a plurality of symbols, the method comprising the steps of:
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subtracting a postcursor estimation signal from the input signal to produce a difference signal which is used to generate the estimated signal; generating all possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on a past estimated signal in a second past symbol period which is at least two symbols earlier; and selecting one of the possible postcursor estimation signals based on the estimated signal to produce a selected one as the postcursor estimation signal in the symbol period. - View Dependent Claims (16)
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17. A method for generating an estimated signal from an input signal in each symbol period, the input signal being received through a channel having an impulse response including a precursor component for N symbols and a postcursor component for M symbols, where N and M are an integer, the method comprising the steps of:
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subtracting the precursor component from the input signal to produce a first difference signal; storing the first equalized signal to delay one symbol; subtracting the first difference signal depending on a postcursor estimation signal to produce a second difference signal which is used to generate the estimated signal; generating all possible postcursor estimation signals in a first past symbol period which is one symbol earlier based on a past estimated signal in a second past symbol period which is at least two symbols earlier; and selecting one of the possible postcursor estimation signals based on the estimated signal to produce a selected one as the postcursor estimation signal in the symbol period. - View Dependent Claims (18)
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Specification