Irradiance Distribution and System Analysis of Optical Wave Propagation Through Turbulence in the Presence of a Random Distribution of Particles

Optical signals propagating through a foggy atmosphere suffer from severe attenuation in the order of hundreds of dB. Research in the literature suggested statistically modeling the signal attenuation in foggy links. However, the proposed distribution is mathematically intractable, and further investigations were based on simulations and imposing restrictions on the distribution parameters. In this article, irradiance distributions for optical waves propagating through a random distribution of particles are derived based on the Rytov theory. The distribution parameters are explicitly related to the channel physical characteristics. Moreover, general distributions describing signal fading due to the combined effect of turbulence, pointing errors, and scattering particles are also derived. In case of a foggy link, use is made of the generalized Meijer-G function to derive closed-form expressions without undue restrictions on the distribution parameters. Closed-form expressions of the corresponding average bit error rate (ABER) for optical wireless communication (OWC) under many modulation schemes are derived. Spatial diversity is also considered through single-input multiple-output (SIMO) systems. The work in this article shows that, within the complete scattering theory, significant system losses exist beyond those previously reported in the literature, and this should be accounted for in the link budget design of optical wireless links.