Localization Accuracy Improvement of a Visible Light Positioning System Based on the Linear Illumination of LED Sources

As a new technique of indoor localization, visible light positioning has the advantages of high accuracy and antielectromagnetic interference. Received signal strength (RSS) based visible light positioning method is easy to implement because it requires simple hardware structure. However, in practical scenarios, the actual channel gain does not follow the ideal channel model. Instead of Lambertian channel model, some approximations have to be adopted to describe the relationship between received optical power and distance, and these approximations will cause deviation of positioning calculation. In this paper, an optical antenna based on freeform lens design is proposed to improve the accuracy of RSS-based positioning. With the optical antenna, the luminous intensity distribution is optimized, and the relationship between received optical power and distance becomes a simple linear relationship. Results show that RSS-based positioning system using freeform lens optical antenna can improve the positioning accuracy by 44%. Furthermore, the advantage of the optical antenna we designed for a visible light communication positioning system demonstrated uniformity under different conditions.