Compensation of filter symbol interference by adaptive estimation of received symbol sequences
First Claim
1. Apparatus for compensating for distortion in received digital symbol values wherein each received symbol value represents one of a plurality of transmitted symbol values, such apparatus comprisingmeans for altering a received symbol value by a preselected amount, said amount being in response to an estimate of the transmitted symbol values represented by said received symbol value and N other received symbol values, where N is an integer greater than zero;
- means for comparing said altered symbol value to a closest one of said plurality of transmitted symbol values to determine any difference therebetween; and
means for outputting said closest one of said plurality of transmitted symbol values in lieu of said received symbol value if said difference meets a prescribed criterion.
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Accused Products
Abstract
Compensation for arbitrary combinations of linear and nonlinear distortion is provided by altering a received symbol value by a preselected amount. This amount is based on an estimate of the sequence of transmitted symbol values represented by the received symbol value at a sampling time and a number of received symbol values at other sampling times. The altered symbol value is then compared with the closest one of the possible transmitted symbol values to determine the difference, if any, therebetween. The closest one of the possible transmitted symbol values is then outputted if the difference meets a prescribed criterion. If not, the received symbol value is altered by a different amount in response to another estimate until the recited difference meets the prescribed criterion. In the disclosed embodiments, the foregoing technique is incorporated in a memory-based canceler or transversal filter.
55 Citations
26 Claims
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1. Apparatus for compensating for distortion in received digital symbol values wherein each received symbol value represents one of a plurality of transmitted symbol values, such apparatus comprising
means for altering a received symbol value by a preselected amount, said amount being in response to an estimate of the transmitted symbol values represented by said received symbol value and N other received symbol values, where N is an integer greater than zero; -
means for comparing said altered symbol value to a closest one of said plurality of transmitted symbol values to determine any difference therebetween; and means for outputting said closest one of said plurality of transmitted symbol values in lieu of said received symbol value if said difference meets a prescribed criterion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of compensating for distortion in received digital symbol values wherein each received symbol value represents one of a plurality of transmitted symbol values, said method comprising the steps of
altering a received symbol value by a preselected amount, said amount being in response to an estimate of the transmitted symbol values represented by said received symbol value and N other received symbol values, where N is an integer greater than zero; -
comparing said altered symbol value to a closest one of said plurality of transmitted symbol values to determine any difference therebetween; and outputting said closest one of said plurality of transmitted symbol values in lieu of said received symbol value if said difference meets a preselected criterion. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification