Partial-response-channel precoding
First Claim
1. Apparatus comprisingmeans for selecting, in response to input data, a sequence of signal points from a predetermined base constellation,means for combining each selected signal point with a feedback signal to provide a sequence of combined signal points, said feedback signal being a predetermined function of at least one previously provided one of the combined signal points, said base constellation and said function being such that ones of said combined signal points are signal points of said base constellation and the others are signal points of minimally non-overlapping lattice translates of said base constellation, andmeans for providing a transmit signal which represents said combined signal points, all of the combined signal points which are minimally non-overlapping lattice translates of one another being represented identically.
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Abstract
Digital data is transmitted over partial-response channels using a precoding technique which allows for the use of a wide variety of transmit constellations. A sequence of signal points is selected from a predetermined base constellation meeting particular criteria. A so-called combined signal point is developed for a present symbol interval by a) selecting a signal point from the base constellation as a function of input bits associated with the present symbol interval and b) combining the signal point thus selected with a feedback signal which is a function of one or more combined signal points that were developed for previous symbol intervals, that function being determined by the characteristic of the partial-response channel. A transmit signal which represents the combined signal points is then provided. In one implementation, the processing steps are performed explicitly using an integrated precoder/constellation mapper. In another implementation those steps are performed implicitly using table look-up.
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Citations
27 Claims
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1. Apparatus comprising
means for selecting, in response to input data, a sequence of signal points from a predetermined base constellation, means for combining each selected signal point with a feedback signal to provide a sequence of combined signal points, said feedback signal being a predetermined function of at least one previously provided one of the combined signal points, said base constellation and said function being such that ones of said combined signal points are signal points of said base constellation and the others are signal points of minimally non-overlapping lattice translates of said base constellation, and means for providing a transmit signal which represents said combined signal points, all of the combined signal points which are minimally non-overlapping lattice translates of one another being represented identically.
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8. Apparatus comprising
means for generating in response to a sequence of binary input words a sequence of transmit symbols of a predetermined transmit constellation, said binary input words having a predetermined number of different values which is substantially equal to the number of symbols of said transmit constellation, and means for transmitting said sequence of transmit symbols over a channel which has a predetermined partial-response characteristic and which provides in response to said sequence of transmit symbols a sequence of receiver symbols of an expanded receiver constellation, said generating means including means for selecting, for each of said words, a respective symbol of said transmit constellation, said selecting and said constellation being such that each word can be recovered from a respective one of said receiver symbols independent of any other one of said receiver symbols, each of said transmit symbols having at least first and second coordinates and said transmit constellation and said expanded receiver constellation being other than M2 -ary quadrature amplitude modulation constellations.
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11. Apparatus for use in a data communication system in which a sequence of transmit symbols selected from a predetermined transmit constellation in response to binary input data is transmitted over a communication channel having a predetermined partial-response characteristic, said binary input data having a predetermined number of different values which is substantially equal to the number of symbols of said transmit constellations, said channel providing, in response to said transmitted symbols, a sequence of receiver symbols of an expanded receiver constellation, each of said transmit and receiver symbols having at least first and second coordinates, each transmit symbol being selected for a respective binary word of said data in such a way that that binary word can be recovered from a respective one of said receiver symbols independent if any other one of said receiver symbols,
said apparatus comprising means for receiving said sequence of receiver symbols, and means for recovering said data from the sequence of receiver symbols received by said means for receiving in response to stored information which associates each different receiver symbol with a different binary word value, the values of the bits of each said binary word value interdependently identifying the values of the first and second coordinates of the associated receiver symbol.
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13. A method comprising the steps of
selecting, in response to input data, a sequence of signal points from a predetermined base constellation, combining each selected signal point with a feedback signal to provide a sequence of combined signal points, said feedback signal being a predetermined function of at least one previously provided one of the signal points, said base constellation and said function being such that ones of said combined signal points are signal points of said base constellation and the others are signal points of minimally non-overlapping lattice translates of said base constellation, and providing a transmit signal which represents said combined signal points, all of the combined signal points which are minimally non-overlapping lattice translates of one another being represented identically.
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21. A method comprising the steps of
receiving input data, processing said input data to generate in response thereto a sequence of transmit symbols of a predetermined transmit constellation, and transmitting said sequence of transmit symbols over a channel which has a predetermined partial-response characteristic and which provides in response to said sequence of transmit symbols a sequence of receiver symbols of an expanded receiver constellation, each of said transmit symbols having at least first and second coordinates, said processing step including the step of selecting, for each of a succession of subsets of said input data, a respective symbol of said transmit constellation, said selecting and said constellation being such that each subset can be recovered from a respective one of said receiver symbols independent of any other one of said received symbols, said subsets having a predetermined number of different values which is substantially equal to the number of symbols of said transmit constellation, and said selecting step being such that at least two of the coordinates of at least ones of the transmit symbols are selected jointly by at least a portion of the respective subset.
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26. A method for use in a data communication system in which a sequence of transmit symbols selected from a predetermined transmit constellation in response to binary input data is transmitted over a communication channel having a predetermined partial-response characteristic, said channel providing, in response to said transmitted symbols, a sequence of receiver symbols of an expanded receiver constellation, each transmit symbol being selected for a respective binary word of said data in such a way that that binary word can be recovered from a respective one of said receiver symbols independent of any other one of said receiver symbols, there being a number of different binary word values, that number being substantially equal to the number of symbols of said transmit constellation,
said method comprising the steps of receiving said sequence of receiver symbols, and recovering said data from the sequence of received receiver symbols in response to stored information which associates each different receiver symbol with a different stored binary word value, said transmit constellation and said expanded receiver constellation being other than M-PAM or M2 -ary quadrature amplitude modulation constellations.
Specification