Experimental Investigation of Modulation Method for Visible-Light Communications

Hidemitsu SUGIYAMA  Shinichiro HARUYAMA  Masao NAKAGAWA  

IEICE TRANSACTIONS on Communications   Vol.E89-B   No.12   pp.3393-3400
Publication Date: 2006/12/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.12.3393
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Optical Wireless Communications
visible-light communication,  optical wireless communication,  LED,  modulation,  PPM,  

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We have developed a new modulation method--inverted pulse position modulation (I-PPM) and subcarrier inverted pulse position modulation (SC-I-PPM)--that provides superior LED brightness for visible-light communications. In addition, the new modulation method SC-I-PPM is not affected by background light. In this paper, we investigated several modulation methods in details and set up a standard with which to evaluate the performance of modulation methods. Several modulation methods are subjected to experiments to clarify their performance. Experiments show that subcarrier modulation suppresses the influence of background light and that our new modulation best maintains LED brightest.