Theoretical Bit Error Rate in a Circular Polarized Optical OFDM System


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E99-A   No.1   pp.177-184
Publication Date: 2016/01/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E99.A.177
Type of Manuscript: Special Section PAPER (Special Section on Wideband Systems)
optical wireless communications,  OFDM,  circular polarization,  theoretical analysis,  

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Circular Polarized Optical OFDM (CPO-OFDM) is a system that applies OFDM to optical wireless communications. This system separates OFDM signals into positive and negative signals and converts these signals into left-handed and right-handed polarization and then multiplexes the resulting polarized signals. In CPO-OFDM, the separated signals must be combined at the receiver. Then, as a noise-reduction method, the comparison method compares the signal amplitudes of the positive and negative signals and uses the signal having the larger amplitude as the received signal. However, if we use the comparison method when the received signals have background light, the combined signals are distorted. In the present paper, we herein report a method by which the receiver estimates the amplitude of the background light and then removes the background light, which is easily accomplished. Furthermore, we also report a theoretical method for analyzing the bit error rate (BER). We develop a closed form of the theoretical formula for the BER in an additive white Gaussian noise (AWGN) channel. By using this formula and through numerical integration, we investigate the theoretical BER for a scintillation channel. We compare the results of the theoretical analysis with those of the simulations. As a result, the theoretical BER is generally coincident with the BER obtained through simulation. Even if we use the closed-form formula, we can derive the BER with sufficient accuracy.