Optical Camera Communications: Principles, Modulations, Potential and Challenges

Abstract

Optical wireless communications (OWC) are emerging as cost-effective and practical solutions to the congested radio frequency-based wireless technologies. As part of OWC, optical camera communications (OCC) have become very attractive, considering recent developments in cameras and the use of fitted cameras in smart devices. OCC together with visible light communications (VLC) is considered within the framework of the IEEE 802.15.7m standardization. OCCs based on both organic and inorganic light sources as well as cameras are being considered for low-rate transmissions and localization in indoor as well as outdoor short-range applications and within the framework of the IEEE 802.15.7m standardization together with VLC. This paper introduces the underlying principles of OCC and gives a comprehensive overview of this emerging technology with recent standardization activities in OCC. It also outlines the key technical issues such as mobility, coverage, interference, performance enhancement, etc. Future research directions and open issues are also presented.

Performance of Vehicular Visible Light Communications under the Effects of Atmospheric Turbulence with Aperture Averaging

“…In OCC systems, an image quality metric known as the PSNR is used for assessing the link’s quality, which is given by [ 41 ]: where = 255 for the grayscale image (i.e., the maximum possible pixel value), and MSE is the pixel luminance mean squared error, which is defined by [ 16 ]: where are the pixel values for the transmitted symbols, (in this work we have obtained from captured images at approximately a zero distance from the Tx, i.e., without considering the channel impact), are the average pixel values for the received symbols, n is the number of rows (i.e., the on and off states of the Tx for OOK signaling scheme), and j is the pixel’s row index number.…”

“…It is worth noting that optical wireless systems (visible and infrared bands) employing camera-based Rxs offer relatively lower data rates compared with the high-speed PD-based Rxs, due to the camera frame rates. However, the low data rate R b feature of optical camera communications (OCC) should not be seen as a problem, considering that there are many applications, including VC [ 16 ], indoor localization [ 16 ], Internet of Things (IoT) [ 16 ], sensor networks, motion capturing [ 17 ], and advertising [ 18 ], where R b is considerably low. In OCC systems, each pixel at the receiving image sensor can detect signals at different wavelengths over the visible range, e.g., red, green, and blue (RGB), hence offering parallel detection capabilities, an adaptive field of view feature, and even enhanced R b using multiple-input multiple-output [ 16 , 19 ] and artificial neural network-based equalizers [ 20 ].…”

“…However, the low data rate R b feature of optical camera communications (OCC) should not be seen as a problem, considering that there are many applications, including VC [ 16 ], indoor localization [ 16 ], Internet of Things (IoT) [ 16 ], sensor networks, motion capturing [ 17 ], and advertising [ 18 ], where R b is considerably low. In OCC systems, each pixel at the receiving image sensor can detect signals at different wavelengths over the visible range, e.g., red, green, and blue (RGB), hence offering parallel detection capabilities, an adaptive field of view feature, and even enhanced R b using multiple-input multiple-output [ 16 , 19 ] and artificial neural network-based equalizers [ 20 ]. In addition, the information carrying light beams from different sources and many directions via the line-of-sight (LOS) [ 21 , 22 ], non-LOS, and/or both paths [ 23 ] can be captured using the camera-based Rxs with the extended transmission range [ 24 ] compared with the PD-based links.…”

Wireless Sensor Networks Using Sub-Pixel Optical Camera Communications: Advances in Experimental Channel Evaluation

“…Optical camera communications (OCC), the sub-field of visible light communications (VLC) in which receivers ( ) are implemented using image sensors [ 1 ], has excellent potential to be part of the evolution of new technologies beyond the fifth generation of cellular networks (5G). The use of cameras represents a low integration cost due to their massive availability in end-user devices such as smartphones, public infrastructure surveillance cameras, and vehicular security dash cameras.…”

“…For example, PD-based VLC systems exceeding Gbps throughput have been reported [ 2 , 3 ]. In contrast, the frame rate of conventional cameras poses an inherent limitation to OCC’s data rate, but the image-forming optics and the ability to visualize different objects within the field-of-view (FOV) can be exploited to increase the throughput [ 1 , 4 , 5 , 6 ].…”