The free space optical communication system has become remarkably important nowadays due to huge benefits associated with it. However, atmospheric induced laser beam scintillation remains a challenge that has been addressed using different techniques over the years. Multipulse position modulation has been analyzed over the generalized atmospheric turbulence model (M distribution) using bit error rate (BER), ergodic channel capacity, and outage probability as performance metric measures. Using Meijer's G functions closed form expressions for the said performance metrics have been derived. Next, using the derived closed form expressions, a thorough investigation of how the BER, ergodic channel capacity, and the outage probability are affected by the atmospheric turbulence conditions and other parameters, such as operational wavelength, has been carried out. It has been observed that increasing the modulation level cannot significantly reduce the transmitted power required for a targeted BER in strong atmospheric turbulence channels. Also the outage probability increases with increasing threshold signal-to-noise ratio. © 2020 Society of Photo-Optical Instrumentation Engineers (SPIE).