Constellation-code division multiplex for digital HDTV

Constellation-code-division multiplexing (C-CDM), in which subchannels divide the constellation signal point codewords and the subchannel error probability are changed by varying the distances between signal point codewords in the constellation diagram, is described. Quadrature amplitude modulation (QAM) multiplexed by the C-CDM method is called shifted rectangle QAM (SRQAM). SRQAM provides a set of terrestrial digital HDTV broadcasting coverage areas with multiple layers of error probability. By calculating the error probability, coverage areas can be simulated and compared with areas obtained for the proposed 32 QAM. The results show that HDTV area is reduced by 15%, but EDTV area is increased by 32%