Pulse position modulation based optical spatial modulation over atmospheric turbulence channels

Spatial modulation (SM) is a recently proposed effective multiple input multiple output communications technique. In this paper the performance of SM in free space optical (FSO) systems under atmospheric turbulence channels is analyzed. Pulse position modulation (PPM) is used as the modulation technique. In the performance results the benefits of utilizing modulation instead of just using antenna index is observed through decrease in bit error rates in the expense of decreased spectral efficiency.