An Analytical Performance Study of a Non-Line-of-Sight Optical Camera Communication System Based on Rolling Shutter and Color Shift Keying

Rolling Shutter is a mechanism employed in CMOS-based cameras for capturing images. It has been explored in Optical Camera Communications to improve transmission data rates. Additionally, the Color Shift Keying modulation scheme, which combines pulse amplitude modulation and wavelength division multiplexing techniques, utilizes three or more color LEDs. By integrating Color Shift Keying modulation with the Rolling Shutter mechanism, cameras can achieve higher data rates compared to other modulation schemes used in Visible Light Communication. However, the application of Rolling Shutter-based Optical Camera Communication in non-line-of-sight scenarios, particularly with Color Shift Keying, remains largely unexplored. This study aims to characterize the performance of a non-line-of-sight camera communication system that employs Rolling Shutter. To assess the system’s performance, a camera communication model was developed using Python. The model considered key factors such as the spectral power distribution of the light source, the spectral reflectance of the surface, and the spectral response of the image sensor. Results from the model confirmed the presence of non-uniform irradiance on the image sensor, particularly on large surfaces, as expected. A Python- based simulator generated three color channel images, enabling estimation of the minimum distance between constellation symbols for two different constellation designs for Color Shift Keying. For a non-line-of-sight scenario, a maximum data rate of 5.76 kbps was estimated.