Free Space Optics Transmission Enabled by PAM-4 Signals: Performance Evaluation Under Indian Weather Conditions

Abstract

This paper presents a performance evaluation of Free Space Optics transmission systems using 4-level pulse amplitude modulation (PAM-4) signals under clear weather conditions and certain specific Indian weather conditions. The conditions at the selected locations, which represent diverse climatic environments, include Chennai, Chandigarh, Jodhpur, and Srinagar. This study provides an assessment of the impact of various conditions in the atmosphere that would affect signal degradation and the quality of transmission based on the bit error rate and eye diagrams of received signals for increasing transmission ranges. The results presented here are the results of the performance analysis of the FSO system with respect to BER as it varies with distance, hence showing the vulnerability of PAM-4 signals due to heavy attenuation by poor weather conditions—mostly fog and rain—under which the selected regions fall. Eye diagrams are also used for signal integrity and quality check and, further on, to gather information on the system under test. This comparative analysis, therefore, brings to light the areas in which the system remains resilient and identifies challenging atmospheric conditions that severely affect transmission. These results provide valuable information on how an FSO system can be optimized under different weather environments, as well as set up strategies through which the reliability and performance of the system can be enhanced for a region with varying atmospheric conditions. The proposed system's performance after performing experimental validation can be used for providing high-speed transmission required for 5G/beyond 5G data transmission networks.