IEEE Photonics Journal (Jan 2013)

Performance Comparison of OFDM Signal and CAP Signal Over High Capacity RGB-LED-Based WDM Visible Light Communication

  • F. M. Wu,
  • C. T. Lin,
  • C. C. Wei,
  • C. W. Chen,
  • Z. Y. Chen,
  • H. T. Huang,
  • Sien Chi

DOI
https://doi.org/10.1109/JPHOT.2013.2271637
Journal volume & issue
Vol. 5, no. 4
pp. 7901507 – 7901507

Abstract

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We experimentally demonstrate a visible light communication (VLC) system based on a single commercially available RGB-type LED. High spectrally efficient carrierless amplitude and phase (CAP) modulation and orthogonal frequency-division multiplexing (OFDM) are adopted in the intensity-modulation and direct-detection VLC system of limited bandwidth. In order to achieve higher capacity of the uneven-frequency-response LED-based VLC system, OFDM signals are combined with the bit- and power-loading techniques, and CAP signals of various modulation are pre-emphasized to modulate one of the RGB chips. To reach the BER of less than 10-3, CAP and OFDM signals demonstrate the maximum data rates of 1.32 and 1.08 Gb/s, respectively, employing the blue chip. In addition to spectrally efficient formats, the wavelength-division-multiplexing (WDM) scheme is applied to further increase the capacity. After individually optimizing RGB chips, the maximum aggregate data rates of CAP and OFDM are 3.22 and 2.93 Gb/s, respectively, in our RGB-LED-based WDM VLC system. Hence, compared with OFDM, the CAP scheme shows competitive performance and provides an alternative spectrally efficient modulation for next generation optical wireless networks.

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