Non-Equiprobable Non-Uniform APSK Constellations Design for BICM Systems

The application of constellations with higher modulation orders ensures higher communication rates. Besides, to further improve the performance, non-uniform constellations (NUCs) are used to reduce the gap between channel capacity and the Shannon limit. However, the demapping complexity of NUCs is higher compared to the traditional quadrature amplitude modulation (QAM) constellation due to their irregular shape. This paper proposes a design method for non- equiprobable non-uniform constellations based on APSK, called NE-NUAPSK. Simulation results show that the 1024- and 4096-order constellations obtained using our design method have a performance improvement of up to 0.20 dB compared with the NUCs in ATSC 3.0, and the demapping complexity can be reduced by up to 84%. Compared with non-uniform amplitude phase shift key (NUAPSK) constellations, our constellation has comparable performance with a demapping complexity reduction of up to 87.5%.