Analysis of performance limitations in optical wireless communication system due to laser source impairment (RIN) and background noise

Abstract

Optical Wireless Communication (OWC) is a promising technology in several science and industry sectors, owing to its unique features: easy to install, no licenses needed, high speed communication, low power consumption and secure. However, OWC terrestrial applications suffers from limitations due to noise caused by natural phenomena such as fog, haze and rain and the Relative Intensity Noise (RIN) of the laser. In this paper, the performance evaluation, in terms of Signal to Noise Ratio (SNR) and the corresponding Bit Error Rate (BER) of terrestrial OWC is analysed in presence of laser RIN and background noise under different weather conditions and link distances. Simulation results of the mathematical model presented in this paper shows that, according to the typical values of parameters used here, RIN has, in general, negligible effect on the system performance at relatively high laser output power (which corresponds to laser injection current) for all weather conditions. In addition, background noise power (solar radiation) is higher in clear weather conditions and this may affect the OWC system even when the attenuation of channel is low at clear weather condition. Moreover, in general, SNR is relatively high (BER is low (improved)) for clear weather condition. However, when the weather becomes worse due to haze, fog or rain, attenuation of channel increases due to decreasing of visibility and this leads to decrease SNR and degrades BER (system performance).