| Visible light communication is a novel wireless optical communication technology and rose with development of white LED fabrication techniques. White LED devices are used not only for illuminating rooms but also for an optical wireless communication system which is suitable for indoor private networks. Visible light communication will provides a safety, facility communication condition.This paper studies an indoor visible light communication system based on white LED lights. We discuss the channel characteristics of visible light communication, analyze the communication link of indoor visible light communication. We mainly research the modulation methods used in visible light communication. In the past, OOK was used for digital data modulation primarily, but the data transmission rate was limited because of the ISI effect. In the paper, OFDM which can absorb the ISI effect is considered in combination with higher order modulation schemes. Based on numerical analyses and computer simulations, it is confirmed that the scheme could be used for indoor illumination and wireless high data rate transmission. In the end we consider some schemes for realization of visible light communication modulation for the next step of researches and experiments. |
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