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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 20 — Oct. 7, 2013
  • pp: 24288–24299

Reverse polarity optical-OFDM (RPO-OFDM): dimming compatible OFDM for gigabit VLC links

Hany Elgala and Thomas D. C. Little  »View Author Affiliations

Optics Express, Vol. 21, Issue 20, pp. 24288-24299 (2013)

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Visible light communications (VLC) technology permits the exploitation of light-emitting diode (LED) luminaries for simultaneous illumination and broadband wireless communication. Optical orthogonal frequency-division multiplexing (O-OFDM) is a promising modulation technique for VLC systems, in which the real-valued O-OFDM baseband signal is used to modulate the instantaneous power of the optical carrier to achieve gigabit data rates. However, a major design challenge that limits the commercialization of VLC is how to incorporate the industry-preferred pulse-width modulation (PWM) light dimming technique while maintaining a broadband and reliable communication link. In this work, a novel signal format, reverse polarity O-OFDM (RPO-OFDM), is proposed to combine the fast O-OFDM communication signal with the relatively slow PWM dimming signal, where both signals contribute to the effective LED brightness. The advantages of using RPO-OFDM include, (1) the data rate is not limited by the frequency of the PWM signal, (2) the LED dynamic range is fully utilized to minimize the nonlinear distortion of the O-OFDM communication signal, and (3) the bit-error performance is sustained over a large fraction of the luminaire dimming range. In addition, RPO-OFDM offers a practical approach to utilize off-the-shelf LED drivers. We show results of numerical simulations to study the trade-offs between the PWM duty cycle, average electrical O-OFDM signal power, radiated optical flux as well as human perceived light.

© 2013 OSA

OCIS Codes
(060.4080) Fiber optics and optical communications : Modulation
(060.4510) Fiber optics and optical communications : Optical communications
(200.4560) Optics in computing : Optical data processing
(230.3670) Optical devices : Light-emitting diodes

ToC Category:
Fiber Optics and Optical Communications

Original Manuscript: July 26, 2013
Revised Manuscript: September 12, 2013
Manuscript Accepted: September 14, 2013
Published: October 3, 2013

Hany Elgala and Thomas D. C. Little, "Reverse polarity optical-OFDM (RPO-OFDM): dimming compatible OFDM for gigabit VLC links," Opt. Express 21, 24288-24299 (2013)

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