Technique for achieving the full coding gain of encoded digital signals
AssigneeAT&T Bell Laboratories
InventorsAhmad K. Aman, Robert L. Cupo, Nicholas A. Zervos
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Abstract
In a telephone local loop transmission arrangement, data is communicated from the customer premises to the central office utilizing a multidimensional, passband signal illustratively at 480 kb/s. Specifically, the transmitted signal is encoded in a trellis code and precoded using a generalized partial response filter. The received signal is processed by a circuitry that implements a trellis decoding in combination with nonlinear filtering.
Claims13
Apparatus for use in a communications system wherein transmitted data symbols can be represented by allowable signal points lying within a plurality of signal point subsets, said plurality of signal point subsets forming a signal constellation encompassing an associated region and the transmitted data symbol at each of a succession of times being represented by an allowable signal point in one signal point subset, said apparatus comprising
- means for receiving the transmitted data symbol at each of said succession of times;
- and
- means for assigning each received data symbol to a plurality of preferred signal points lying within an expanded constellation encompassing an expanded region and including said allowable signal points and at least one artificial signal point, each artificial signal point corresponding to a different allowable signal point and each preferred signal point in said plurality corresponding to a different one of said plurality of signal point subsets.
The apparatus of claim 11 wherein each preferred signal point is assigned based on physical proximity of the received data symbol at each of said succession of times to the allowable and artificial signal points in said expanded constellation.
A method for use in a communications system wherein transmitted data symbols can be represented by allowable signal points lying within a plurality of signal point subsets, said plurality of signal point subsets forming a signal constellation encompassing an associated region and said transmitted data symbol at each of a succession of times being represented by an allowable signal point in one signal point subset, said apparatus comprising
- receiving the transmitted data symbol at each of said succession of times;
- and
- assigning each received data symbol to a plurality of preferred signal points lying within an expanded constellation encompassing an expanded region and including said allowable signal points and at least one artificial signal point, each artificial signal point corresponding to a different allowable signal point and each preferred signal point in said plurality corresponding to a different one of said plurality of signal point subsets.
Dependencies are inferred from the claim text.