Abstract:

A new coded modulation scheme is proposed using fewer constellation points than normal quadrature amplitude modulation (QAM). With properly designed code rate and labeling strategy, it is not necessary to map one to one from bit vectors to channel symbols. Iterative decoding and demodulation of the new scheme could obtain earlier turbo cliff compared with the coded modulation system with normal QAM constellation. As an example, a new constellation is constructed to replace the commonly used 64QAM based on the design rules of such systems. Experiments show the effectiveness of the new scheme.

Key words: labeling strategy, coded modulation, soft decoder, bit interleaved coded modulation with iterative detection