4 × 20 Gbps OFDM Based RoFSO Transmission Using Hybrid SCM-MDM Under Different Turbulence Conditions

Abstract

A bandwidth efficient Orthogonal Frequency-Division Multiplexing - Radio over Free Space Optics (OFDM-RoFSO) system based on 2-level multiplexing with SCM and MDM domain is implemented. A total of 4-input data streams are multiplexed before being transmitted through RoFSO link. A 4 × 20 Gbps data rate is achieved by per- forming multiplexing at SCM level with 45 GHz, 60 GHz subcarrier frequencies and then at MDM level with HG01 and LG10 optical modes. With certain design enhancements, channel capacity can be further increased to multi-fold levels. The performance of transmitted input data streams 1–4 is investigated for Bit Error Rate (BER), Q-factor, received signal power, SNR and turbulence conditions under clear air, haze, rain, fog and dust conditions. Eye diagram and electric constellation patterns are analyzed for reliable data transmission. Thus, by using proposed design with 2-level multiplexing, a higher transmission capacity and low crosstalk levels are easily achieved.