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HOME > Encouragement of Learning > Encouragement of Visible Light Communications

Encouragement of Visible Light Communications

NAKAGAWA, Masao (Ph.D)

Experimental test: TV-screen image was modulated and sent to a guidance LED (at Keio Techno Mall 2003)

Antennas of mobile phones, viewed from a school building of Hiyoshi Campus. (The snow-capped mountain behind the building is Mt. Fuji.) You may find mobile phone antennas on a rooftop of building and at the top of electric pole.

Mobile phones being the most familiar with the public, wireless communication became nothing special around us. A telephone placed in the living room used to be something that we were unfamiliar with, and consciously or unconsciously tended to give a wider berth to. Nowadays, however, electric wave for mobile phone comes into home or to a terminal on hand, from the top of a steel tower located several kilometers away. On the other hand, being linked with invisible lines, we cannot tell who is using it. This is raising a problem when mobile phones have made progress to this extent. When there is an accident, for example, you usually dial 110 to call the police or 119 to the firehouse. In most cases, recently, it is made from a mobile phone. This often is a big problem for emergency dispatch of the police or fire crews. The caller can be located from the phone number when it was made from a home phone, but it is not possible when it was made from a mobile phone. When the police asked, "Which building?" the sender would answer, "Inside the building around Hibiya." It would bring them nowhere. It is a virtually impossible task to detect the origin of electric wave. An idea that I developed is that on-off positioning information is modulated constantly in illumination of lighting equipment and emergency light, the on-off information is received by mobile phone's camera to send it to the emergency number 110 or 119. The on-off information blinks rapidly, and thus is not bad for your eyes. By sending positioning information from fixed light that you see, you may find the exact location of you. It sends the map of the building where you are, with your location at the center, in addition to "which hallway on what floor of what building." In this way, the police or fire crews can dash off without worry about the location. Visible light communications can be used for operational control of buildings and factory facilities, and mobile robots in the future. We may call such visible light communications as ubiquitous light communications, integration between visible light communications and ubiquities computing, for which establishment of VLCC (Visible Light Communications Consortium) is being advanced. At present, 20 companies including NEC Corporation, Matsushita Electric Works, Ltd., Agilent Technologies, and KDDI Corporation participated in the VLCC. Visible light communications allow you to receive on-off positioning information "where you are" and others easily from illumination and emergency light here and there. We appreciate it if you suggest us interesting applications of visible light communications.