Time and Spatial Jitter Influence on the Performance of FSO Links with DF Relays and OC Diversity Over Turbulence Channels

Abstract

FSO communication is a viral technology among optical wireless communications, gathering the interest of both researchers and manufacturers. This is because of the many advantages associated with FSO communication, including high data rates, reliability, safety, and economy. However, there are several unavoidable drawbacks that shadow the performance of FSO systems. For example, atmospheric turbulence is a well-known problem related to the weather conditions of the channel, which causes the scintillation effect. Also, spatial jitter due to pointing errors is a critical factor of the link’s performance, caused by occasional misalignments between the transmitter and the receiver. Moreover, time jitter is another limiting agent that deteriorates the total throughput, inducing bit stream misdetections, caused by the arrival of out-of-sync pulses. All three effects have been exhaustively studied and many statistical models and interesting solutions have been proposed in the literature to estimate their magnitude and compensate for their impact. In this work, the turbulence effect was treated by Málaga distribution, the spatial jitter effect was regulated by the non-zero boresight model, and the time jitter effect was modeled by the generalized Gaussian distribution. Various modulation schemes were studied, along with DF multi-hop and optimal combining diversity techniques at the receiver’s end. New, accurate mathematical expressions of average BER performance have been obtained, and valuable conclusions were drawn thanks to the presented numerical results.