Using Everyday Lighting for Communication
These days, there's no need to explain the usefulness of wireless communications using radio waves. We take radio waves for granted, even though the human eye cannot see them. But position detection with cellular telephones and car navigation systems that use radio waves is not very accurate, as there is some difficulty in identifying the exact location of the information terminal. This drawback becomes more pronounced when equipment is used in underground shopping malls or inside buildings.
Professor Nakagawa says, "I have spent many years researching mobile communications using radio waves. Now that the age of the ubiquitous network society is all but upon us, I have devoted a lot of thought to issues related to wireless communications. All this thinking led me to the possibility of adding data to visible light generated by equipment, including lights we use our every day, traffic signals and illuminated signs, and using the result for communication. This is where the original concept for visible light communications comes from."
Professor Nakagawa is suggesting the creation of a new world of wireless communication, in which visible light communication is used to supplement communication not feasible using only radio waves. Several years ago, some members of the Institute of Electronics, Information and Communication Engineers (http://www.ieice.org/jpn/index/html) conducted basic research on this concept. Keeping pace with this research, rapid advances were made to raise the performance and expand the applications of LEDs, resulting in the real prospect of the practical application of visible light communications. The VLCC, with Professor Nakagawa as chairman, came into being in November 2003. With a current membership of 15 companies, the consortium is engaged in R&D aimed at the commercialization of visible light communications systems.
Beamed to the World from CEATEC JAPAN
Visible light communications use LEDs, which send data by flashing light at speeds undetectable to the human eye. One major advantage is that we can use the infrastructure around us without having to make any changes.
For example, the transmission of positional information entered into individual indoor LED lighting devices and sent to a cellular telephone or similar device enables position detection that is accurate to within several meters. Theoretically, precision is possible to within several millimeters, and it is at this level that the true power of visible light communications will be realized, such as in controlling robots. To give another example, all sorts of information can be sent to cars and pedestrians using LED traffic signals.
Visible light communications are an attractive option for the instantaneous transmission of huge quantities of data. If machines that send and receive data are placed a few centimeters apart, visible light can be used to exchange data between them. Because the light that is being used is visible to the human eye, it is obvious at a glance which pieces of equipment are communicating. This does away with mechanical verification that has been necessary up until now.
Professor Haruyama says, "Regardless of the extent of the business potential of visible light communications, we won't know the direction that product development will take until its applications become more clearly defined. Professor Nakagawa took up this topic in his address at CEATEC JAPAN last year. This year, however, there will be a number of actual systems on display. We are calling 2004 "Year One for Visible Light Communications," and we are very keen to see this uniquely domestic technology find a world-wide audience.
Four Exhibits Showcase the Possibilities of Visible Light
Thanks to the support of companies belonging to VLCC, there will be four exhibits at this year's CEATEC JAPAN showcasing the myriad possibilities of visible light communications in easy-to-understand formats.
Light and Sound Collaboration (Supported by Keio University, Agilent Technologies Japan, Ltd., and Sony Corporation)
Musicians each play a different instrument under red, green and blue lights. When visitors wearing headphones turn in the direction of one of these lights, they will be able to hear only the sound of the instrument receiving that particular colored light. By making the most of the visibility of this light, visitors will be able to instinctively choose the information they want to receive.
LED Traffic Signal Communication System (Supported by Nippon Signal Co., Ltd., and Nagoya Institute of Technology)
The traffic signals we see everyday are gradually being replaced by LEDs. If visible light communications are applied in this area, it will be possible to send all sorts of information from traffic signals to cars and pedestrians waiting for lights to change. Visible light communications is beginning to receive attention as a new communications medium for intelligent transport systems.
Illumination ID, Receiving Light via Mobile Terminals and Light Tags (Supported by Keio University, NEC Corporation and Matsushita Electric Works, Ltd.)
Visible light is used to send ID information from LED illumination on mobile phones and other mobile terminals. Even in places such as in underground shopping malls, where radio waves cannot easily reach, extremely accurate position information and image and text data can be transmitted instantaneously. Though LEDs are commonly used to display whether a device is on or off, light tags go further, as they can send detailed information on a device from an LED to a mobile terminal.
Visible Light Communications Applied to Cellular Telephone Displays (Supported by Cyber Solutions Laboratories, Nippon Telegraph and Telephone Corporation)
There is a form of communication, based on visible light with varying hues, that uses existing cellular telephone displays. Simply holding the handset up to a large screen transmits the telephone's ID. Also, merely pointing the phone in the direction of desired information on-screen causes the relevant information to be downloaded onto the phone. One main attraction of this technology is that it utilizes existing infrastructures, such as iAPRI.
You may watch these intriguing demonstrations at the Visible Light Communication Consortium Booth, Digital Network Stage/Business & Society Zone/Hall 5/5B31.