Development of visible light wireless communication technology based on white LED

After in 1996 Nichia Nakamura Professor: blue LED, on behalf of the red, green and blue colors LED finally all in place. Because LED have lightweight, low power consumption, high speed response, so the three RGB LED which has been regarded as the next generation of white light, Taiwan, Japan and South Korea, the United States and European countries have joined the ranks of the development of white LED. At present, the white LED is mostly applied in the field of LCD backlight module, traffic signal lamp, portable electronic machine backlight module and so on. Traditionally, the use of invisible light to carry out communications transmission, mostly using a longer wavelength of infrared light, in this part, has been quite mature, and the matching standards are widely used by the industry. Visible light communication is a new generation technology of wireless communication, which uses the high speed response of visible light, such as LED. Visible light communications will limit the receiving area, and is suitable for use in the show, tour guides, pedestrian road induced by an intelligent traffic system (ITS: IntELligent Transport Systems), hospitals, indoor information transmission etc.. According to the data transmitting end will transfer the electrical signals into tone, then LED light transmitted, the receiving end of the light receiving element (light sensor) receiving light, then light into electrical signals, after reading data as polyphonic signal. Therefore, the development of visible light, with the naked eye is easy to identify the source of information is not easy to occur mechanical malfunction or impact on the human body, no electromagnetic damage, and so on. The international consortium VLCC was founded in October 2003, (Visible Light Communication Consortiun production), to join at the beginning of the establishment of enterprises as the main object, according to the VLCC and application of visible light communication technology popularization of various standards working group activities, to January 2007 in order to enhance the visibility of the visible light communication, including Toshiba and other companies, there are 23 member companies the formal working group activities, specific content is the portable terminal, optical label (Tag) is reviewed, and the establishment of visible light ID standardization working group. Visible light communication is lighting and signage and other peripheral equipment commonly used communication technology, in order to make visible light communication popularization, standardization is necessary to establish a variety of terminal machines can be used, at present VLCC has developed two kinds of specifications, respectively, visible light communication system specification VLCC-STD-001, and low visible light ID with visual communication light ID specification VLCC-STD-003. Is the scope of application of communication system in the visible light as the media, especially the system is divided into the physical layer and upper layer application, the applicable provisions of the physical layer part, including the receiving end of the light emitting element and the receiving end of the light receiving element and a light emitting element free space interface. In terms of wavelength because of the use of visible light, so the wavelength from the blue 380nm to the red 780nm range. The frequency distribution of the part of the original signal can be modulated by the transmission mode, in addition to the application of the optical communication system, the typical transmission system as well as infrared communication system, etc.. In order to prevent the interference of the space transmission system, the frequency of the secondary transmitting wave of the visible optical communication system is also worked out. Visible light communication will limit the reception area, it is very suitable for the application of road guidance, exhibition guide, intelligent traffic system. LED point light source visible light wireless communication device completely eliminates the traditional high-frequency wireless electromagnetic waves on the human body and the surrounding electronic machine interference doubts, suitable for application in the field of office and hospital limited space data transmission, etc..

Source: DIGITIMES