A coding and modulation apparatus and method are presented, particularly for use in a system according to IEEE 802.11. The apparatus comprises an encoder configured to encode input data into cell words according to an LDPC code and a modulator configured to modulate said cell words into constellation values of a non-uniform constellation and to assign bit combinations to constellation values of the used non-uniform constellation. The modulator is configured to use a non-uniform constellation and bit labeling from one of the several groups of constellations, which constellation show quadrant and octant symmetry.