PAPR Reduction in DCO-OFDM Visible Light Communication Systems Using Optimized Odd and Even Sequences Combination

Abstract

This paper proposes a novel peak-to-average power ratio (PAPR) reduction scheme, which has several advantages, such as low-complexity candidate construction and no side information (SI) transmission in direct current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) visible light communication (VLC) systems. In the proposed scheme, the candidates can be generated by linearly combining time-domain even and odd sequences with cyclic shift and phase rotation. Even and odd sequences are obtained by adopting an inverse fast Fourier transform on the even and odd parts of a Hermitian symmetry encoded signal, respectively. Furthermore, a deterministic and efficient selection method of cyclic shift and phase rotation is derived to improve PAPR reduction performance and ensure that each candidate is unique, so that the receiver can recover the transmitted candidate signal without the use of SI. Simulation results show that the proposed scheme can achieve comparable PAPR reduction performance with the conventional selected mapping (CSLM) scheme with random and chaotic sequences, but at a considerably low computational complexity. Moreover, the proposed blind SI detection scheme provides almost the same bit error rate (BER) performance as that of the CSLM scheme with a perfect SI detection and symmetric selected mapping for a DCO-OFDM VLC system with 1024 subcarriers and 16-QAM. In contrast to other related time-domain sequences that combine methods used for DCO-OFDM systems, the proposed scheme improves BER performance with a slight increase in computational complexity and PAPR.

RIS-Assisted Visible Light Communication Systems: A Tutorial

“…Non-standardized modulation schemes: OFDM cannot be applied directly in VLC due to the restrictions of IM/DD schemes (real and positive values of transmitted signals). Therefore, different variations of OFDM have been proposed, such as direct current (DC) biased optical OFDM [52], asymmetrically clipped DC-biased optical OFDMs [53], asymmetrically clipped optical OFDM [54], fast-OFDM, and polar-OFDM. Among the OWC versions of OFDM, optical OFDM techniques were proposed with an aim of applying schemes such as QAM to VLC systems.…”

Comparative Analysis of Optical Multicarrier Modulations: An Insight into Machine Learning-based Multicarrier Modulation

“…The bit stream is first transmitted through a serial-to-parallel converter so that the encoded parallel bit stream can be modulated on to the subcarriers using Inverse Fast Fourier Transform (IFFT). The inclusion of guard intervals and cyclic prefix helps in the elimination of inter-symbol interference and inter-carrier interference respectively [11]. At the receiving end, frequency offset estimation and symbol timing is done so that Fast Fourier Transform (FFT) is applied on the symbols to detect the modulated subcarriers.…”

Amplitude-Coherent Detection for Optical Wireless Communications: Opportunities and Limitations

“…The high PAPR may also introduce positive peaks clipping effects as the practical LEDs have the typical nonlinear characteristics. The PAPR problem has been extensively investigated for both RF [24]- [27] and OWC [17], [28]- [31], where the main focus of most researchers is to minimize the PAPR and avoid bit error rate (BER) degradation, while reducing the computational complexity and the required side information.…”