CODING AND MODULATION APPARATUS USING NON-UNIFORM CONSTELLATION

A coding and modulation apparatus and method are presented. The apparatus (10) comprises an encoder (11) that encodes input data into cell words, and a modulator (12) that modulates said cell words into constellation values of a non-uniform constellation. The modulator (12) is configured to use, based on the total number M of constellation points of the constellation and the signal-to-noise ratio SNR in dB, a non-uniform constellation from a group of constellations comprising one or more constellations defined by a constellation position vector comprising a predetermined number of constellation positions, wherein in one or more constellation position vectors two or more constellation positions are identical resulting from a condensation of preliminary constellation positions optimized before.