Novel APM constellation design for spatial modulation systems

As an entirely hybrid modulation scheme, the performance of spatial modulation (SM) is highly dependent on the specific type of digital modulation schemes. In this paper, a novel amplitude phase modulation (APM) constellation design method suitable for SM transmission is proposed. The designed APM constellation has multi-ring structure with each ring's constellation similar with PSK constellation. Moreover, efficient searching algorithm is provided by traversing over the possible ring number, the constellation points' number in each ring, and the radius of each ring. Simulation results show that the novel design method could successively achieve the APM constellations superior to the traditional PSK and QAM constellations over independent Rayleigh fading channels.