Optical spatial pulse position amplitude modulation over atmospheric turbulence channels

We propose spatial pulse position amplitude modulation (SPPAM) as a novel optical signaling scheme with the capability of having higher power and spectral efficiencies than those of conventional optical modulation techniques. We evaluate the performance of SPPAM in free space optical (FSO) communication systems over weak-to-moderate and moderate-to-strong atmospheric turbulence channels and provide average bit error probability (ABEP) bounds for both uncoded and coded performances. Theoretical derivations are validated with simulation results which show that SPPAM forms a feasible alternative to other FSO modulation approaches.