Modulation bandwidth enhancement of white-LED-based visible light communications using electrical equalizations

D. H. Kwon, S. H. Yang, S. K. Han

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Citations (Scopus)

Abstract

Utilizing the modulation capability of LEDs, there have been many studies about convergence technology to combine illumination and communication. The visible light communication (VLC) system has several advantages such as high security, immunity to RF interference and lower additional cost than comparing to LEDs just for illumination. However, modulation bandwidth of LEDs is not enough for various wireless communication systems. Since the commercial LEDs are designed only for lighting systems; we need an effort to enhance the modulation characteristics of LEDs. When the area of LED is increased, internal junction capacitance of LED is also increased depending on the area of LEDs and then the RC delay time of LED is increased. As a result, the modulation bandwidth of LEDs is limited by large RC delay time. In addition, frequency response of commercial white LED is degraded by the slow response time of the used yellow phosphor. Thus, modulation bandwidth of VLC system is limited to several MHz which is not enough to accommodate high data rate transmission. In this paper, we designed equalization circuit using RLC component for compensating the white LEDs frequency response. Also, we used blue filtering to improve frequency response of white LEDs, which is degraded by yellow phosphorescent component. Power loss by optical filtering and distance is compensated by convex lens. Consequently, we extend the modulation bandwidth of VLC system from 3 MHz to more than 180 MHz, and it allows NRZ-OOK data transmission up to 400 Mbps at 50 cm.

Original languageEnglish
Title of host publicationBroadband Access Communication Technologies IX
EditorsBenjamin B. Dingel, Katsutoshi Tsukamoto
PublisherSPIE
ISBN (Electronic)9781628414776
DOIs
Publication statusPublished - 2015 Jan 1
EventBroadband Access Communication Technologies IX - San Francisco, United States
Duration: 2015 Feb 102015 Feb 12

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9387
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Other

OtherBroadband Access Communication Technologies IX
CountryUnited States
CitySan Francisco
Period15/2/1015/2/12

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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  • Cite this

    Kwon, D. H., Yang, S. H., & Han, S. K. (2015). Modulation bandwidth enhancement of white-LED-based visible light communications using electrical equalizations. In B. B. Dingel, & K. Tsukamoto (Eds.), Broadband Access Communication Technologies IX [93870T] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9387). SPIE. https://doi.org/10.1117/12.2078680