Universal and Effective Decoding Scheme for Visible Light Positioning Based on Optical Camera Communication

As a promising approach to implement indoor positioning, visible light positioning (VLP) based on optical camera communication (OCC) image sensor has attracted substantial attention. However, the decoding schemes of existing VLP systems still face many challenges. First, the transmission channel between transmitters and receivers can be easily affected by environmental changes, resulting in poor thresholding performance. Second, the inherently unsynchronized air transmission channel issue remains a big obstacle for decoding data. The above two problems limit the application of VLP systems, where various mobile devices are used as receivers and the properties of transmission channel are constantly changing with the movement of receivers. In this paper, a universal and effective decoding scheme named pixel-to-bit calculation (PBC) decoding algorithm for VLP systems is proposed and experimentally demonstrated. It includes a Staged Threshold Scheme which provides excellent thresholding performance for different transmission channel conditions, as well as a Synchronous Decoding Operation to automatically synchronize the clock between transmitters and receivers. A decoding rate of 95.62% at the height of 2.73 m is realized in a practical Robotic-based VLP system embedded with our proposed PBC decoding scheme. In addition, experimental results show that the average decoding rate of the proposed PBC decoding scheme reaches 99.9% when applying different transmitters and receivers

CGA-VLP: High Accuracy Visible Light Positioning Algorithm Using Single Square LED with Geomagnetic Angle Correction

Visible light positioning (VLP), benefiting from its high accuracy and low cost, is a promising technology for indoor location-based services. In this article, the theoretical limits and error sources of traditional camera-based VLP systems are analyzed. To solve the problem that multiple LEDs are required and auxiliary sensors are imperfect, a VLP system with a single square LED which can correct the geomagnetic angle obtained from a geomagnetic sensor is proposed. In addition, we conducted a static positioning experiment and a dynamic positioning experiment integrated with pedestrian dead reckoning on an Android platform to evaluate the effectiveness of the proposed method. According to the experimental results, when the horizontal distance between the camera and the center of the LED is less than 120 cm, the average positioning error can be retained within 10 cm and the average positioning time on the mobile phone is 39.64 ms