Abstract
Optical camera communications (OCC) research field has grown recently, aided by ubiquitous digital cameras; however, atmospheric conditions can restrict their feasibility in outdoor scenarios. In this work, we studied an experimental OCC system under environmental phenomena emulated in a laboratory chamber. We found that the heat-induced turbulence does not affect our system significantly, while the attenuation caused by fog does decrease the signal quality. For this reason, a novel strategy is proposed, using the camera’s built-in amplifier to overcome the optical power loss and to decrease the quantization noise induced by the analog-digital converter of the camera. The signal quality has been evaluated using the Pearson’s correlation coefficient with respect to a reference template signal, along with the signal-to-noise ratio that has been empirically evaluated. The amplification mechanism introduced allows our system to receive the OCC signal under heavy fog by gradually increasing the camera gain up to 16 dB, for meteorological visibility values down to 10 m, with a correlation coefficient of 0.9 with respect to clear conditions.
Highlights
Digital cameras are ubiquitous consumer electronics and are being explored to deliver extra capabilities beyond traditional photography and video
We describe the relevant processes involved in the Complementary Metal-OxideSemiconductor (CMOS) camera mechanism of acquisition in Rolling Shutter (RS)-based Optical camera communications (OCC) employed by our system and derive the analytical tools used for the evaluation of its performance in the experimental setting
Channel Modelling In CMOS image sensors, the red-green-blue (RGB) light from a Bayer filter impinges the subpixels. These entities are integrated by PDs and their driving circuit and are grouped by rows connected in parallel to amplifiers and analog/digital converter (ADC) units that are shared by columns
Summary
Digital cameras are ubiquitous consumer electronics and are being explored to deliver extra capabilities beyond traditional photography and video. OCC has been investigated as one of the Visible Light Communication (VLC) schemes [1]. OCC implemented within internet of things (IoT) environments provides multiple functionalities of vision, data communications, localization and motion detection (MD) [2,3] used in various IoT-based network applications including device-to-device communications [4], mobile atto-cells [5], vehicular communications [6,7,8], and smart cities, offices, and homes (SCOH) [9]. The majority of new generation smart devices have built-in Complementary Metal-OxideSemiconductor (CMOS) image sensors, providing the ability to capture photos and videos [10,11]. The strategy behind using a CMOS camera for OCC is that the image sensor performs an acquisition mechanism known as Rolling Shutter (RS), in which it sequentially integrates light on rows of pixels [12]
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