Should Analogue Pre-Equalisers be Avoided in VLC Systems?

Li, Xicong; Ghassemlooy, Zabih; Zvánovec, Stanislav; Pérez‐Jiménez, Rafael; Haigh, Paul Anthony

doi:10.1109/jphot.2020.2966875

Cited by 15 publications

(11 citation statements)

References 27 publications

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“…In this way, the proposed scheme can overcome the problem of bandwidth efficiency. Equalization techniques [39,40] and different modulation formats such as OFDM [41] can be implemented to improve the reception success rate and the BER performance for low-speed and high-speed VLC links, respectively. The scheme can also be tested for various transmission ranges between the LED and camera-and PD-based Rxs along with different angular orientations to support mobility in OIoT environments.…”

Section: Conclusion and Future Outlookmentioning

confidence: 99%

A SIMO Hybrid Visible-Light Communication System for Optical IoT

Teli

Chvojka

Vítek

et al. 2022

IEEE Internet Things J.

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Section: Conclusion and Future Outlookmentioning

confidence: 99%

A SIMO Hybrid Visible-Light Communication System for Optical IoT

Teli

Chvojka

Vítek

et al. 2022

IEEE Internet Things J.

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“…For example, using pre-and post-equalizations with the emitter degenerated LED driver increase the 3 𝑑𝐵 𝐵𝑊 of the blue, red, and green LEDs by 174, 180, and 145 MHz, respectively [6]. However, these methods cause a significant reduction in the received signal-to-noise ratio (SNR) [9][10].…”

Section: Introductionmentioning

confidence: 99%

DFT Spread-Optical Pulse Amplitude Modulation for Visible Light Communication Systems

Saied¹,

Rabie

2022

IEEE Access

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DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) has been proposed in visible light communication (VLC) to overcome the limited modulation bandwidth of light emitting diode (LED). Due to the implementation of the inverse fast Fourier transform at the DCO-OFDM transmitter, DCO-OFDM suffers from its high peak-to-average power ratio (PAPR), which restricts its use in some VLC applications, especially where the optical power efficiency is a crucial requirement. That is because the LEDs used in VLC systems have a limited optical power-current linear range. To this end, a novel discrete Fourier transform spread-optical pulse amplitude modulation (DFTS-OPAM) signal scheme based on the single carrier-interleaved frequency division multiple access (SC-IFDMA) signal is introduced in this paper to address the high PAPR issue of OFDM. DFTS-OPAM is achieved by considering a PAM as an SC-IFDMA data symbol and duplicate the output vector of the fast Fourier transform at the SC-IFDMA transmitter side. Simulation results show that the PAPR of the proposed scheme is 7 dB lower than that of DCO-OFDM. Furthermore, this significant PAPR improvement is experimentally investigated where the practical results show that the proposed scheme can provide more 2.5 dB reduction in the average transmitted power requirement compared to DCO-OFDM and can subsequently increase the maximum achieved distance between the transmitter and the receiver by 44%.INDEX TERMS single carrier frequency division multiple access, DC-biased optical orthogonal frequency division multiplexing; visible light communication, peak-to-average power ratio, light-emitting diode, dynamic range.

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“…It is unnecessary to use blue filters if multi-carrier modulation schemes, especially with bit-loading, are applied because multi-carrier modulation can utilise all of the signal power in the full received light spectrum to achieve higher SNR and, therefore, higher system capacity, or data rates [ 26 ]. Similarly, analogue pre-equalisers [ 27 , 28 ] are designed to compensate for the frequency response of the LED to extend the normalised 3-dB bandwidth by sacrificing the modulation depth, which leads to the same issue as using blue filters [ 29 ]. Hence, we adopted a multi-band carrierless amplitude and phase modulation (CAP) [ 30 , 31 , 32 ] with bit-loading to combat the limited bandwidth problem due to its simple implementation and low peak-to-average power ratio (PAPR) [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

A 40 Mb/s VLC System Reusing an Existing Large LED Panel in an Indoor Office Environment

Ghassemlooy

Zvánovec

et al. 2021

Sensors

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With advances in solid-state lighting, visible light communication (VLC) has emerged as a promising technology to enhance existing light-emitting diode (LED)-based lighting infrastructure by adding data communication capabilities to the illumination functionality. The last decade has witnessed the evolution of the VLC concept through global standardisation and product launches. Deploying VLC systems typically requires replacing existing light sources with new luminaires that are equipped with data communication functionality. To save the investment, it is clearly desirable to make the most of the existing illumination systems. This paper investigates the feasibility of adding data communication functionality to the existing lighting infrastructure. We do this by designing an experimental system in an indoor environment based on an off-the-shelf LED panel typically used in office environments, with the dimensions of 60 × 60 cm2. With minor modifications, the VLC function is implemented, and all of the modules of the LED panel are fully reused. A data rate of 40 Mb/s is supported at a distance of up to 2 m while using the multi-band carrierless amplitude and phase (CAP) modulation. Two main limiting factors for achieving higher data rates are observed. The first factor is the limited bandwidth of the LED string inside the panel. The second is the flicker due to the residual ripple of the bias current that is generated by the panel’s driver. Flicker is introduced by the low-cost driver, which provides bias currents that fluctuate in the low frequency range (less than several kilohertz). This significantly reduces the transmitter’s modulation depth. Concurrently, the driver can also introduce an effect that is similar to baseline wander at the receiver if the flicker is not completely filtered out. We also proposed a solution based on digital signal processing (DSP) to mitigate the flicker issue at the receiver side and its effectiveness has been confirmed.

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Should Analogue Pre-Equalisers be Avoided in VLC Systems?

Cited by 15 publications

References 27 publications

A SIMO Hybrid Visible-Light Communication System for Optical IoT

A SIMO Hybrid Visible-Light Communication System for Optical IoT

DFT Spread-Optical Pulse Amplitude Modulation for Visible Light Communication Systems

A 40 Mb/s VLC System Reusing an Existing Large LED Panel in an Indoor Office Environment

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