Performance Analysis of Dual-Beam Free Space Optical Communication Link under Dust and Rain Conditions

Abstract

Free space optical (FSO) communication has become an enduring and well-established communication technology in the last few decades with several advantages of high data rate, enormous bandwidth, low power consumption, transportable technology without right of way, and inherently secure line of a sight communication system. The invisible, intensity-modulated signal of light propagated through the air and detected on the receiver side experiences attenuation because of uneven distribution of rain droplets, suspended dust aerosol particles, and the droplet size distribution of fog particles in atmospheric layer degrade performance of FSO communication link. The ever-increasing demand for high data rate has quest for an innovative research for a communication link. In this paper, the performance of a dual-beam FSO communication link is evaluated under rain and dust as attenuation conditions. The system parameters, such as link distance transmitted and received power, link distance, diameter of transmitter and receiver aperture, and divergence angle, are optimized for a metropolitan FSO communication link. Dual-beam FSO communication signal propagated through an estimated attenuation level at 30 dBm transmitted power for link distance up to 2.5 km. The optical power splitter and power combiners are used in the simulation to estimate different channel parameters without the MIMO technique. The information signal of the 10 Gbps data rate is internally modulated using the NRZ generator, externally modulated by the Mach-Zehnder, and an optical signal transmitted through a dual-beam optical spectrum frequency of 193.1 THz using power splitter technique apart from each other. A comprehensive analysis is performed to design and assess robust optical communication systems through efficiency parameters such as received power, optical signal-to-noise ratio (OSNR), bit error rate (BER), and Q-factors. Results show that received optical power is a weather-dependent variable that shows a decreasing pattern as weather attenuation increases. Likewise, Q-factor and OSNR show similar decreasing trend with introduction of rain and dust as attenuator; however, BER increases in presence of attenuation.