Design and development of free space optic (FSO) communication haze and rain weather conditions

Abstract

This research was conducted to study the effects of haze and rainfall on the improved performance of FSO system. An FSO system is an optical wireless system which use atmosphere as the transmission medium. Despite excellent advantages of high bandwidth, secured, low cost and flexibility, it is vulnerable towards weather conditions such as haze and rain as these phenomena cause signal attenuation due to the atmospheric scattering. An FSO system with improved performance under these heavily attenuated conditions was selected from three different proposed designs of FSO system. These three designs of FSO system were made and simulated using simulation software called OptiSystem. Compared to the basic design of FSO system which only has one FSO channel, Design 1 has been installed with two optical channels. Then the effects of rain and haze were studied on the design based on the Bit Error Rate (BER) and Q Factor achieved. From the result analysis, Design 2 was proposed as an effort to improve the system performance of Design 1. Compared to Design 1, Design 2 has two CW lasers as optical source installed and just one optical channel. The two-beam link and single FSO channel have improved the system performance in term of the BER and Q Factor. The BER reduced and the Q Factor increased. Based on the simulation analysis of Design 1 and Design 2, Design 3 has been ultimately proposed as a measure to create the best improved FSO system which could operate the most efficiently in haze and rain conditions compared to the previous designs. Design 3 was installed with an optical amplifier at both transmitter and the receiver sides to amplify the optical signal and maintain it at a high level. The design has also been installed with five optical channels to increase the scattering attenuation on the system for study purposes. Despite that, the system still operated at high performance and still has a better performance than Design 1 and Design 2. In the study, several parameters were altered for the purposes of the research, namely bit rate, effective received power, link distance, aperture diameter and attenuation. Bit Error rate and Q Factors of the proposed designs were analysed to study the improved performance of FSO system in rainy and hazy days. Theoretical analysis was done on the data collected from the meteorological centre and the results were used for the simulation analysis using Optisystem.