Comparison of Asymmetrically Clipped Optical OFDM and DC-Biased Optical OFDM in AWGN

Armstrong, Jean; Schmidt, B.

doi:10.1109/lcomm.2008.080193

Cited by 604 publications

(340 citation statements)

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“…Moreover, there are three popular types of OOFDM proposed for VLC systems, i.e. asymmetrically clipped OOFDM (ACO-OFDM) [61], [67], DC biased OOFDM (DCO-OFDM) [62], [68] as well as unipolar OFDM (U-OFDM) [63]. The milestones of popular modulation schemes employed in VLC systems are summarized in the timeline of Table VII.…”

Section: Phy Techniques 1) Modulation Schemesmentioning

confidence: 99%

Optimization of Visible-Light Optical Wireless Systems: Network-Centric Versus User-Centric Designs

Zhang

Hanzo

2018

IEEE Commun. Surv. Tutorials

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Abstract-In order to counteract the explosive escalation of wireless tele-traffic, the communication spectrum has been gradually expanded from the conventional radio frequency (RF) band to the optical wireless (OW) domain. By integrating the classic RF band relying on diverse radio techniques and optical bands, the next-generation heterogeneous networks (HetNets) are expected to offer a potential solution for supporting the ever-increasing wireless tele-traffic. Owing to its abundant unlicensed spectral resources, visible light communications (VLC) combined with advanced illumination constitute a competent candidate for complementing the existing RF networks. Although the advantages of VLC are multi-fold, some challenges arise when incorporating VLC into the classic RF HetNet environments, which may require new system architectures. The user-centric (UC) design principle for VLC environments constitutes a novel and competitive design paradigm for the super dense multi-tier cell combinations of HetNets. The UC concept may be expected to become one of the disruptive techniques to be used in the forthcoming fifthgeneration era. This paper provides a comprehensive survey of visible-light-aided OW systems with special emphasis on the design and optimization of VLC networks, where the radically new UC design philosophy is reviewed. Finally, design guidelines are provided for VLC systems.

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Section: Phy Techniques 1) Modulation Schemesmentioning

confidence: 99%

Optimization of Visible-Light Optical Wireless Systems: Network-Centric Versus User-Centric Designs

Zhang

Hanzo

2018

IEEE Commun. Surv. Tutorials

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“…In ACO-OFDM, because of Hermitian symmetry and insertion of zeros, only one fourth of the carries transmit useful information. The advantage of ACO-OFDM in comparison with DCO-OFDM is that it requires less power for a given BER level [9].…”

Section: A Vlc Ofdm Systemsmentioning

confidence: 99%

Unsupervised time domain nonlinear post-equalization for ACO-OFDM visible light communication systems

Ávila

Lovisolo

2017

2017 25th European Signal Processing Conference (EUSIPCO)

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Abstract-LED nonlinearity is an important issue limiting the performance of Visible Light Communication (VLC) systems. This form of distortion is particularly problematic when the system employs Optical-OFDM because of the high Peak-toAverage Power Ratio (PAPR) of its time domain symbol. This paper proposes using ancillary statistical properties of the O-OFDM signal in order to mitigate LED nonlinearities in an unsupervised fashion. By exploring the Gaussianity of the time domain OFDM signal and the idea of distribution equalization, we propose a semi-parametric approach to blind nonlinear post-equalization for asymmetrically clipped O-OFDM (ACO-OFDM) VLC systems. In addition to not requiring training data, the equalizer is robust to different LED types and it is adaptive to time-varying nonlinearities. Simulations with a realistic LED model show that the developed tool is capable of substantially mitigating the effects of nonlinear distortion on system performance.

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“…The eU-OFDM signal is a combination of superimposed independent U-OFDM signals, and, therefore, its average time-domain electrical power grows with the number of signals that are superimposed. It can be derived as [8,18]:…”

Section: Electrical Powermentioning

confidence: 99%

OFDM-Based Visible Light Communications

Tsonev

Islim

Haas

2016

Signals and Communication Technology

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This chapter provides an overview of latest enhancements of the orthogonal frequency division multiplexing (OFDM) based visible light communications. The principals of OFDM techniques for intensity modulation and direct detection (IM/DD) systems are explained in details in [1]. A number of inherently unipolar OFDM techniques were recently proposed as power efficient alternatives to the widely deployed direct-current-biased optical orthogonal frequency division multiplexing (DCO-OFDM). The unipolar orthogonal frequency division multiplexing (U-OFDM) technique achieves higher power efficiency compared to DCO-OFDM. However, due to the spectral efficiency loss of U-OFDM technique, the power efficiency advantage over DCO-OFDM starts to decrease as the spectral efficiency increases. Multiple U-OFDM streams are superimposed in enhanced unipolar orthogonal frequency division multiplexing (eU-OFDM) to double the spectral efficiency of U-OFDM technique. For the first time, the novel eU-OFDM allows unipolar OFDM techniques to have same spectral efficiency of DCO-OFDM. In this chapter, the concept of eU-OFDM is generalized to GeneRalizEd ENhancEd UnipolaR OFDM (GREENER-OFDM), and extended to other unipolar OFDM schemes (asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) and pulse-amplitude-modulated discrete multitone modulation (PAM-DMT)). IntroductionThe physical properties of commercially available light emitting diodes (LEDs) and photodiodes (PDs), which are the foremost candidates for low-cost front-end devices in optical wireless communications (OWC), allow OWC to be realised as Dobroslav Tsonev · Mohamed Sufyan Islim · Harald Haas Li-Fi Research and Development Centre, The University of Edinburgh, Edinburgh EH9 3JL, http://www.lifi-centre.com e-mail: h.haas@ed.ac.uk 1 2 Dobroslav Tsonev, Mohamed Sufyan Islim, and Harald Haas intensity modulation and direct detection (IM/DD) systems only. This is because light emitted by of-the-shelf LEDs is incoherent and so information can be reliably encoded only in the signal intensity. The phase and the amplitude of the light wave cannot be modulated or detected with LEDs and PDs. This limits the set of conventional modulation schemes that can be adopted from the field of radio frequency (RF) communications and directly translated into OWC. Signal modulation techniques such as on-off keying (OOK), pulse-position modulation (PPM), and M-ary pulse-amplitude modulation (M-PAM) are relatively straightforward to implement as they provide real signals that can be directly mapped to light intensity. However, as transmission rates increase, the limited modulation bandwidth of the front-end devices and the limited bandwidth of the OWC channel lead to intersymbol interference (ISI) in the time-domain modulation signal. Hence, a technique such as orthogonal frequency division multiplexing (OFDM) becomes more appropriate as a modulation scheme. OFDM enables simple cost-effective equalisation with single-tap equalisers in the frequency-domain. In add...

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Comparison of Asymmetrically Clipped Optical OFDM and DC-Biased Optical OFDM in AWGN

Cited by 604 publications

References 9 publications

Optimization of Visible-Light Optical Wireless Systems: Network-Centric Versus User-Centric Designs

Optimization of Visible-Light Optical Wireless Systems: Network-Centric Versus User-Centric Designs

Unsupervised time domain nonlinear post-equalization for ACO-OFDM visible light communication systems

OFDM-Based Visible Light Communications

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