Information delivery tactile pavings using visible light communication

In Japan, there are tactile pavings for visually impaired persons walk support. Tactile pavings tell existence of a way and escalator. Tactile pavings are tool to tell. And, it is one of the auxiliary systems of navigation. Military GPS (global positioning system) became public welfare apparatus. And it is convenience for visually impaired persons. So we propose a navigation system for visually impaired persons. The precision of GPS is about 10m. The precision of IPS (Indoor positioning system) using technology of wireless LAN (A-GPS: assisted GPS) is about 5m. Similarly the precision of visible light communication using lighted is about 5m. This precision is not good for visually impaired persons walking on tactile pavings. We propose the method of sending information using visible light communications from tactile pavings, not from the roof. Our proposal is good precision, because distance of between transmitter and receiver is short. Visible light communication transmits information by flashing light. It can transmit to pinpoint area, because of the linearity of light. However received signals from the neighboring tactile pavings interfere each other. Avoiding interference requires the multiple access method. So we use CDMA (code division multiple access). And we made a prototype and confirmed good precision.