Free space optical communication is impaired by atmospheric effects such as weather conditions, attenuation, scattering
and turbulence. We investigate the effect of using different intensity modulation schemes on combating atmospheric
turbulence. The results show that the intensity modulated beam is more resistant to turbulence with the differential pulse
position scheme showing the better performance in comparison to the pulse position scheme, whereas the on-off keying
scheme performs the best among the three intensity modulation schemes.