LDPC (Low Density Parity Check) coded 128 DSQ (Double Square QAM) constellation modulation and its associated labeling. A novel means is introduced by which a constellation may be arranged and mapping in its symbols may be determined to provide for improved performance. One application area in which this may be employed is transmission over twisted pair (typically copper) cabling existent within data centers of various networks. The operation of the IEEE 802.3 Ethernet local area networks currently being used (as well as those currently under development) would benefit greatly by employing the various principles presented herein. When this novel approach of an LDPC coded 128 DSQ constellation modulation combined with TH (Tomlinson-Harashima) preceding is employed within a communication device at a transmitter end of a communication channel (i.e., in a transmitter and/or a transceiver), the overall operation of a communication system may improve significantly when compared to prior techniques.