Labeling Non-Square QAM Constellations for One-Dimensional Bit-Metric Decoding

A new modulation scheme is proposed that combines the advantages of APSK and QAM constellations, namely, the low peak power of APSK and the independent processing of the real and imaginary components of QAM. The new scheme consists of a Gray-labeled non-square QAM constellation and a bit-metric decoder. At a spectral efficiency of 3.5 bits/s/Hz, the new scheme saves 1.35 dB of peak power compared with conventional QAM. The new scheme is implemented with a binary low-density parity-check code. Simulation results are presented.