Abstract
In order to realize a position-based service such as transferring useful information to users located in an area, several infrared-used systems have been proposed. Without making significant changes to the configuration, we added an upload function that helps to send user information to the system. A user can send his/her data by using a handheld device that has a reflective sheet and a liquid crystal on its front. The infrared in the system illuminates in the area where the user's device is lying. When the liquid crystal is clear, the reflective infrared magnitude is large. In contrast, the infrared magnitude is comparatively small when the crystal is dark. An infrared camera placed near the infrared projector recognizes the difference in the magnitude. This difference acts as a communication signal from the user to the system. It is necessary to determines the static threshold for distinguishing these two conditions; however, this is difficult because the difference also depends on the position and angle of the user's device. Therefore, the system we have proposed in this research first recognizes the sync bit sent from the user's device by using a Bayesian network. By means of this recognition process, the threshold can then be determined dynamically. Moreover, our experimental results show that the proposed method can easily overcome previously proposed machine learning methods.
