Abstract—Free space optical (FSO) wireless communication has recently emerged as one of the promising technologies but unfortunately its performance suffer severely from atmospheric turbulence conditions. In this paper, we considered a spatial modulation (SM) as a multiple antenna transmission concept that uses a transmitting antenna index for delivery of information data. In this technique, the advantage of spatial diversity was exploited at the receiver end as a mitigation technique. The performance analysis of free space optical spatial modulation (FSO-SM) system with different diversity combinations such as maximum ratio combining (MRC), equal gain combining (EGC) and selection combining (SC) under the influence of atmospheric-induced turbulence fading is presented. A theoretical error performance using average pairwise error probability (APEP) and the average bit error rate (ABER) for each diversity scheme over lognormal atmospheric turbulence channel are carried out. Based on this analysis, it was found that FSO-SM with MRC performs better than any other spatial diversity under the same atmospheric conditions. The performance of FSO-SM-EGC is also compared with the well-established FSO-Subcarrier Intensity Modulation (SIM)-EGC and the result proved that the proposed configuration provides better mitigation techniques. 
 

Index Terms—Free space optical, spatial modulation, diversity combiners, average pairwise error probability, average bit error rate

Cite: Kehinde O. Odeyemi, Pius A. Owolawi, and Viranjay M. Srivastava, "Free Space Optical System with Spatial Modulation and Diversity Combiners Over Atmospheric Turbulent Channel," Journal of Communications, vol. 14, no. 1, pp. 70-81, 2018. Doi: 10.12720/jcm.14.1.70-81