Analysis of ACO-OFDM, DCO-OFDM and Flip-OFDM for IM/DD Optical-Wireless and Optical-Fiber System

The three types of orthogonal frequency division multiplexing techniques named Asymmetrically -clipped Optical OFDM (ACO-OFDM), DC biased Optical OFDM (DCO-OFDM) and Flip-OFDM systems are analyzed and compared in optical wireless and optical fiber system. Data are taken using MATLAB and the simulation software called Optisystem 13. The techniques are compared in terms of their bit error rate (BER) with respect to electrical energy to the noise power ratio (E-b)/N-o) in presence of additive white Gaussian noise in case of optical wireless channel and by thermal noise in case of optical fiber channel. Different forms of Quadrature Amplitude modulation (QAM) have been used for modulating the OFDM signal such as 4-, 16-, 64 and 256-QAMs. After the final analysis, it is seen that ACOOFDM requires a lower power to reach the target BER of 10-4 compared to DCO-OFDM and Flip-OFDM in both optical wireless and fiber channels. In the last part, the three bipolar OFDM systems are analyzed by observing their receiver sensitivity using PIN photodiode in 25 kin optical fiber channel. The result shows that ACO-OFDM has a better sensitivity than DCO-OFDM and Flip-OFDM.