Theoretical analysis of received optical intensity of underwater image sensor based visible light communications using RGB-LEDs

Recently, Underwater Visible Light Communication (UVLC) has been attracting attention as a short-range underwater wireless communication technology within the range of 100 m. UVLC enables high-speed communication mainly using photodiodes (PD) but requires precise alignment of the optical axis between the transmitter and receiver. In this paper, we investigate the UVLC using image sensors (IS) to establish a more stable communication link easily. Furthermore, focusing on the change of attenuation rate in the visible light band due to the effect of turbidity, chlorophyll concentration, in the underwater transmission channel, we propose an IS-based UVLC using RGBLEDs as the transmitting light, and theoretically evaluate the effect of turbidity in the sea. Specifically, when the chlorophyll concentration is low and high, the lowest attenuation wavelengths are of blue and red respectively. In this paper, we consider image sensor-based UVLC using RGB-LEDs and evaluate how water turbidity affects the transmission light. Also, we evaluate theoretically the effect of turbidity in the sea on the optical RGB signal using a general full-color camera taking into account underwater channel, general convex lens characteristics, and bayer color filter and analog to digital converters (DAC) at CMOS image sensor