Enhancing Performance of FSO Communication Link using Coherent Optical OFDM with Cascaded EDFA

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) and Quadrature Amplitude Modulation (QAM) are the recent existing techniques that are being investigated in Free Space Optical (FSO) communication for the enhancement of Quality of Service (QoS) in provision for longer ranges and higher data rates. Coherent Optical OFDM (CO-OFDM) is capable of providing improved receiver sensitivity and spectral efficiency. The scintillations, atmospheric turbulences and attenuations induced by varying weather (such as rain, fog etc.) conditions pose a serious impact on the link performance. The optical amplifiers and their configuration used in the FSO link design pose an influencing impact on the link performance. The present work incorporates the evaluation of designed FSO communication link using CO-OFDM with Cascaded Erbium Doped Fiber Amplifier (CEDFA) at 30Gbps under the influence of moderate turbulences and geometric attenuations for Clear weather, Heavy rain and Fog (Moderate to Dense) attenuations. The system performance is analyzed for Quality (Q)-Factor, Bit Error Rate (BER), Signal-to-Noise Ratio (SNR) and Constellation diagram as parametric metrics. This novel thought of utilizing cascaded amplifier configuration with CO-OFDM has enabled the implementation of FSO communication over longer distances of 24, 3.9, 1.43 and 0.672 Km for Clear weather, Heavy rain, and Moderate and Dense fog conditions respectively that has not been investigated earlier.