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16 September 2020 Hermitian symmetry free direct current optical-universal filtered multicarrier with companding techniques for intensity modulation/direct detection systems
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Abstract

Hermitian symmetry (HS) is essential for attaining a real-valued signal for intensity modulation and direct detection of visible light communication (VLC). However, HS results in an increase of the peak-to-average power ratio (PAPR). We propose an HS free direct current optical-universal filtered multicarrier (HSF DCO-UFMC) system for VLC. In this technique, the conventional complex UFMC signal is transformed by juxtaposing the real and imaginary components to attain a real valued signal. Therefore, HSF DCO-UFMC offers a great reduction of the PAPR. We also address the nonlinear companding transforms for further reduction of the PAPR of the HSF DCO-UFMC signal. A new companding transform called two μ-law that reduces the PAPR and provides more design flexibility by employing two optimum companding levels and a threshold value is proposed for the HSF DCO-UFMC system. However, this scheme raises the average power level of the signal. So, to maintain a constant average power level, an enhanced two μ-law is proposed to reduce the PAPR effectively. Simulation outcomes exemplify that the proposed HSF DCO-UFMC provides better PAPR reduction. In addition, the proposed two μ-law and enhanced two μ-law can provide an improved PAPR reduction, suppressed side-lobe levels, and better bit error rate performance than the original HSF DCO-UFMC signal.

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2020/$28.00 © 2020 SPIE
Vijaya Durga Chintala and Anuradha Sundru "Hermitian symmetry free direct current optical-universal filtered multicarrier with companding techniques for intensity modulation/direct detection systems," Optical Engineering 59(9), 096104 (16 September 2020). https://doi.org/10.1117/1.OE.59.9.096104
Received: 16 February 2020; Accepted: 26 August 2020; Published: 16 September 2020
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