Wireless visible light communications employing feed-forward pre-equalization and PAM-4 modulation

X. Li, N. Bamiedakis, X. Guo, J. J. D. McKendry, E. Xie, R. Ferreira, E. Gu, M. D. Dawson, R. V. Penty, I. H. White

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

In this paper, feed-forward pre-equalization in conjunction with a PAM modulation scheme are proposed for use in wireless visible light communication (VLC) systems in order to enable the transmission of data rates > 1 Gb/s. Simulation results demonstrate that simple few-tap feed-forward pre-equalization is able to remove the inter-symbol-interference (ISI) caused by the limited link bandwidth of a line of sight (LOS) VLC link, providing up to 5 dB better receiver sensitivity compared with post-equalization. The pre-equalization scheme is implemented for a free-space VLC link using a PAM modulation scheme, which provides an enhanced spectral efficiency compared to NRZ modulation. Micro-pixelated LEDs (μLEDs) are used as the transmitter in this work, as they exhibit higher modulation bandwidth than conventional large-diameter LEDs. An avalanche photodiode (APD) is used at the receiver to provide an enhanced link power budget. Error-free (BER<10-12) 2 Gb/s freespace VLC transmission over 0.6 m is demonstrated experimentally using a simple 3-tap feed-forward pre-equalizer and a PAM-4 modulation scheme. The results show that feedforward pre-equalization with only a few taps can improve the μLED-based link performance greatly, providing a simple and cost-effective solution for high speed VLC links.
LanguageEnglish
Pages2049-2055
Number of pages7
JournalJournal of Lightwave Technology
Volume34
Issue number8
Early online date22 Jan 2016
DOIs
Publication statusPublished - 3 Mar 2016

Fingerprint

pulse amplitude modulation
Pulse amplitude modulation
optical communication
Modulation
Telecommunication links
modulation
taps
Light emitting diodes
light emitting diodes
receivers
Photodiodes
Communication systems
budgets
line of sight
photodiodes
Visible light communication
telecommunication
Bandwidth
high speed
bandwidth

Keywords

  • feed forward equalization
  • micro LED
  • pulse amplitude modulation
  • visible light communication

Cite this

Li, X. ; Bamiedakis, N. ; Guo, X. ; McKendry, J. J. D. ; Xie, E. ; Ferreira, R. ; Gu, E. ; Dawson, M. D. ; Penty, R. V. ; White, I. H. / Wireless visible light communications employing feed-forward pre-equalization and PAM-4 modulation. In: Journal of Lightwave Technology. 2016 ; Vol. 34, No. 8. pp. 2049-2055.
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Wireless visible light communications employing feed-forward pre-equalization and PAM-4 modulation. / Li, X.; Bamiedakis, N.; Guo, X.; McKendry, J. J. D.; Xie, E.; Ferreira, R.; Gu, E.; Dawson, M. D.; Penty, R. V.; White, I. H.

In: Journal of Lightwave Technology, Vol. 34, No. 8, 03.03.2016, p. 2049-2055.

Research output: Contribution to journalArticle

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AU - Gu, E.

AU - Dawson, M. D.

AU - Penty, R. V.

AU - White, I. H.

N1 - (c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

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N2 - In this paper, feed-forward pre-equalization in conjunction with a PAM modulation scheme are proposed for use in wireless visible light communication (VLC) systems in order to enable the transmission of data rates > 1 Gb/s. Simulation results demonstrate that simple few-tap feed-forward pre-equalization is able to remove the inter-symbol-interference (ISI) caused by the limited link bandwidth of a line of sight (LOS) VLC link, providing up to 5 dB better receiver sensitivity compared with post-equalization. The pre-equalization scheme is implemented for a free-space VLC link using a PAM modulation scheme, which provides an enhanced spectral efficiency compared to NRZ modulation. Micro-pixelated LEDs (μLEDs) are used as the transmitter in this work, as they exhibit higher modulation bandwidth than conventional large-diameter LEDs. An avalanche photodiode (APD) is used at the receiver to provide an enhanced link power budget. Error-free (BER<10-12) 2 Gb/s freespace VLC transmission over 0.6 m is demonstrated experimentally using a simple 3-tap feed-forward pre-equalizer and a PAM-4 modulation scheme. The results show that feedforward pre-equalization with only a few taps can improve the μLED-based link performance greatly, providing a simple and cost-effective solution for high speed VLC links.

AB - In this paper, feed-forward pre-equalization in conjunction with a PAM modulation scheme are proposed for use in wireless visible light communication (VLC) systems in order to enable the transmission of data rates > 1 Gb/s. Simulation results demonstrate that simple few-tap feed-forward pre-equalization is able to remove the inter-symbol-interference (ISI) caused by the limited link bandwidth of a line of sight (LOS) VLC link, providing up to 5 dB better receiver sensitivity compared with post-equalization. The pre-equalization scheme is implemented for a free-space VLC link using a PAM modulation scheme, which provides an enhanced spectral efficiency compared to NRZ modulation. Micro-pixelated LEDs (μLEDs) are used as the transmitter in this work, as they exhibit higher modulation bandwidth than conventional large-diameter LEDs. An avalanche photodiode (APD) is used at the receiver to provide an enhanced link power budget. Error-free (BER<10-12) 2 Gb/s freespace VLC transmission over 0.6 m is demonstrated experimentally using a simple 3-tap feed-forward pre-equalizer and a PAM-4 modulation scheme. The results show that feedforward pre-equalization with only a few taps can improve the μLED-based link performance greatly, providing a simple and cost-effective solution for high speed VLC links.

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KW - micro LED

KW - pulse amplitude modulation

KW - visible light communication

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