Recently, the semiconductor technology has improved remarkably by many researchers. And there are many remarkable advanced technologies of LED(Light Emitting Diode) for illumination. LED offers quite advantageous properties such as low power consumption,
reliability, long lifetime and non-Mercury. The LED is the most adaptable light source in present and next generation which replace to incandescent and fluorescent light.
Also, The LED is a good source for visible light communication by its
performance as short switching time. If the LED is controled with switching over 100 times in a sec, the human eye can't see its blinking. And it is possible to use the LED illumination in communication.
There are many researches for LED visible light communication at companies, universities and research organizations. Also I research the visible light communication in an area of sensor network.
In this paper, It is presented a white LED-based optical wireless
communication systems for indoor ubiquitous sensor networks. Each sensor node could access to the server through the PLC(Power Line communication) - Ethernet interface. The proposed system offers a full-duplex wireless link by using different wavelengths to reduce the
inter-symbol interference between uplink and downlink. Through the 1-to-n optical wireless sensor network and PLC modem, the mobile terminals send a temperature data to server. The data transmission speed and distance are 115.2kbps and about 60cm. The AOD(Auto
optical detector) is applied in this system which improve a performance of communication distance. The communication distance is improved to maximum 1.9m when 'AOD' is applied to system.