Pulse or digital communications – Receivers – Particular pulse demodulator or detector
Patent
1994-12-30
1997-08-05
Bocure, Tesfaldet
Pulse or digital communications
Receivers
Particular pulse demodulator or detector
H04L 2706
Patent
active
056549865
ABSTRACT:
A decoding apparatus decides a symbol point in a 2.sup.N -Quadrature Amplitude Modulation("QAM") constellation pattern in response to a modulation function, wherein the 2.sup.N -QAM constellation pattern is divided into 4 subsets, each subset including 2.sup.N-2 symbol points of the constellation pattern; the modulation function representing a N-bit data including 2-bit codeword which indicates a subset of the constellation pattern and (N-2) remaining bits which indicate a symbol point in the subset; and N is an integer greater than 2. The decoding apparatus comprises a metric deciding block for determining an I and Q metrics based on a signal point represented by the modulation function, wherein the I and Q output metrics are determined such a way that the determined I and Q metrics designate a subset of a nearest symbol point from the signal point; a Viterbi decoder for deciding a subset in response to the I and Q metrics, thereby providing a first bit indicating the subset; a hard-decision block for deciding the (N-2) remaining bits; and a decoding block for providing a decoded output for the modulation function in response to the first bit and the (N-2) remaining bits.
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Bocure Tesfaldet
Daewoo Electronics Co. Ltd
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