User Localization and Upstream Signaling for Beam-Steered Infrared Light Communication System

Beam-steered infrared light can provide ultra-high wireless capacity to individual user devices for indoor communication systems. The optical beams used to obtain such high capacities are relatively narrow with the average beam divergence of less than 2.55 degrees, hence an accurate localization system to pinpoint multiple user devices at the same time is required. In addition, an indoor communication should provide mobile coverage to all users, therefore a dynamic and fast localization equipped with a capability of conveying the channel link status of the user devices to optical access points is necessary. In this work, we propose a vision-based technique to simultaneously localize the user devices in a room. A LED-tag system positioned around a photodetector enables the access points to recognize active users. A localization accuracy of 0.018 degrees is achieved within milliseconds. Furthermore, taking advantage of this vision-based system, upstream signaling for channel status information is proposed using M-ary intensity modulation. Experimental results show that an upstream signaling rate of 2.4kbps can be achieved with our simple and low-cost prototype, enabling >10Gbit/s link per user.