Performance evaluation of spatial diversity-based free space optical communication over atmospheric turbulence channels

Abstract

Free space optics is widely regarded as the next-generation high-speed wireless communication technology. It has demonstrated its capability to deliver data faster than any other state-of-the-art wireless communication technique. Moreover, it has emerged recently as an efficient solution to match the larger bandwidth and high data rates requirement of the upcoming wireless communication systems. Optical multiple-input multiple-output (MIMO) scheme was mostly inspired by its recent successes in RF communication, where the employment of multiple antennas leads to the expansion of the wireless channel capacity and/or enhancing the reliability of the wireless communication link. Here we investigate a terrestrial atmospheric FSO communication system operating under the influence of strong atmospheric turbulence-induced, which is modelled as a lognormal channel, and based on MIMO technique with equal gain combining (EGC). Through the use of NRZ line coding, an FSO highly sensitive receiver using either APD or PIN is designed and simulated for best system performance. It was found that APD receiver using Gaussian filter is suited for long-range link with APD gain of 3. Additionally, the system behaviour can be clearly enhanced through the insertion of an amplified version of 2×2 MIMO-FSO technique provided that it is supplemented by booster amplifier.