A new statistical fading model for loss factor induced by angle-of-arrival fluctuations in free space optical communication

The impact of angle-of-arrival (AOA) fluctuations on the loss factor is investigated, and a new fading model is proposed to describe the associated attenuation. Distinct decay characteristics induced by AOA fluctuations are revealed, which depend on the ratio of detector size to beam width (M). The fading model can be divided into two sub-models based on the value of M₀, where M₀ is the value of M when the root-mean-square errors of the two sub-models are equal. In the case of M≽M₀, this fading model follows an inverse S-shaped pattern to describe the impact of AOA fluctuations. When M < M₀, an exponential function to characterize the attenuation induced by AOA fluctuations. The numerical computation results indicate that the proposed fading model offers higher accuracy compared to traditional methods. Furthermore, the continuous analytical expressions for the probability density function (PDF) and cumulative density function (CDF) of the presented fading model caused by AOA are derived. Based on the proposed PDF and CDF models, the outage probability of inter-satellite laser link is analyzed.