Performance Analysis of 20 Gbps-60 GHz OFDM-RoFSO Transmission with ODSB and OSSB Modulation Using Hybrid Mode

Radio-over-free-space-optics (RoFSO) technology is used for transmission of millimeter wave signal using optical network without requiring any optical fiber installation. In this work, the transmission of 20 Gbits/s-60 GHz information is carried out through an OFDM system with 512 subcarriers that are multiplexed in a single channel. By using mode combining technique, Laguerre Gaussian (LG) 01 mode and Hermite Gaussian (HG) 00 modes are combined to generate a hybrid mode for signal transmission in FSO environment. A Dual port Dual drive Mach-Zehnder Modulator (DD-MZM) is configured to generate ODSB and OSSB modulated signals at its output. ODSB and OSSB based systems are compared in terms of received power and signal to noise ratio (SNR) at detector output. A similar analysis is done to measure received power and SNR by using 2, 3 and 4 bit QAM encoder. A 60 GHz RF signal is transmitted through an FSO link using hybrid optical mode to investigate performance in mitigating fading effect due to atmospheric turbulence under clear weather condition.