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3 pages, 162 KiB

Open AccessEditorial

Special Issue on Optical Camera Communications and Applications

by Pankaj Singh and Sung-Yoon Jung

Appl. Sci. 2023, 13(18), 10091; https://doi.org/10.3390/app131810091 - 7 Sep 2023

Viewed by 644

Abstract

Optical Camera Communication (OCC) is a groundbreaking technology that combines optical signals and image sensors for data transmission [...] Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

Research

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14 pages, 751 KiB

Open AccessArticle

Iterative Pilot-Based Reference Frame Estimation for Improved Data Rate in Two-Dimensional Display Field Communications

by Byung Wook Kim, Pankaj Singh and Sung-Yoon Jung

Appl. Sci. 2023, 13(17), 9916; https://doi.org/10.3390/app13179916 - 1 Sep 2023

Cited by 1 | Viewed by 526

Abstract

Recently, display-to-camera (D2C) communication, including display field communication (DFC), has gained attention due to advancements in display technology and the widespread availability of cameras in handheld devices. In this study, we proposed an iterative pilot-based reference-frame estimation scheme to increase the data rate [...] Read more.

Recently, display-to-camera (D2C) communication, including display field communication (DFC), has gained attention due to advancements in display technology and the widespread availability of cameras in handheld devices. In this study, we proposed an iterative pilot-based reference-frame estimation scheme to increase the data rate of a 2D-DFC system. To estimate the reference frame, pilot symbols are inserted between the data symbols of the transmitted image frames. Using pilot symbols, we can compensate for the distortion in the received frame and estimate the data pixels of the reference frames. After the first iteration, we use some of the data symbols as virtual pilot symbols for the next iteration. This process is repeated using both the original and virtual pilots; furthermore, by conducting several iterations, all the data pixels of the reference frame are estimated to reconstruct the reference frame. Simulation results show that the proposed scheme significantly boosts the achievable data rate of the 2D-DFC communication system by almost twofold, while maintaining the unobtrusiveness of the display. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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27 pages, 17498 KiB

Open AccessArticle

Thermal Deformation Stability Optimization Design and Experiment of the Satellite Bus to Control the Laser Communication Load’s Acquisition Time

by Yousheng Shi, Shanbo Chen, Meng Yu, You Wu, Jisong Yu and Lei Zhang

Appl. Sci. 2023, 13(9), 5502; https://doi.org/10.3390/app13095502 - 28 Apr 2023

Cited by 1 | Viewed by 1426

Abstract

The optical axis angle fluctuation due to thermal deformation of the satellite bus between the laser communication load and the star sensor must be constrained to within 0.16 mrad to meet the rapid acquisition needs of the laser communication satellite. This paper analyzes [...] Read more.

The optical axis angle fluctuation due to thermal deformation of the satellite bus between the laser communication load and the star sensor must be constrained to within 0.16 mrad to meet the rapid acquisition needs of the laser communication satellite. This paper analyzes the satellite’s in-orbit temperature field distribution, which is then used as the input boundary condition for the thermal deformation analysis. The optical axis angle fluctuation is reduced by the common reference optimization design. Then, adaptable isolation between the satellite bus structure and the reference support structure reduces the thermal deformation coupling. As a result, there will be less optical axis angle fluctuation caused by thermal deformation. The thermal deformation between the optimized laser communication load and the star sensor installation angle is decreased to 14.25″ according to the entire satellite simulation analysis of the modified structure. The maximum angle variation induced by temperature change dropped from 117.74″ to 10.72″ through the ground temperature deviation and prism calibration tests. The on-orbit alignment test confirms that the required capture time of 30 s is met. The aforementioned work minimizes the uncertain region of laser communication load, lessens the in-orbit acquisition time, and satisfies the demand for speedy acquisition. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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16 pages, 5955 KiB

Open AccessArticle

Design of OCC Indoor Positioning System Based on Flat Panel Light and Angle Sensor Assistance

by Man Feng, Yuru Wang, Mingyang Li, Shi Liu, Guolu Huang and Ping Li

Appl. Sci. 2023, 13(8), 4745; https://doi.org/10.3390/app13084745 - 10 Apr 2023

Cited by 3 | Viewed by 1034

Abstract

Visible light positioning (VLP) technology is a classic application of visible light communication (VLC), which inherits the advantages of VLC and applies it to the field of positioning. LED (light-emitting diode) is a type of light source. Because of its high brightness, aesthetically [...] Read more.

Visible light positioning (VLP) technology is a classic application of visible light communication (VLC), which inherits the advantages of VLC and applies it to the field of positioning. LED (light-emitting diode) is a type of light source. Because of its high brightness, aesthetically pleasing characteristics, and ease of installation, it is used in a variety of indoor lighting applications. However, most of the current VLP technology is still in the laboratory simulation stage and cannot be used in industry or life on a large scale due to various reasons, such as accuracy and cost. Because of the large size of LED flat panel lamps, there are almost no VLP applications with LED flat panel lamps as the emitting light source. Therefore, this paper proposes a VLP technology combining LED flat panel light and a barcode, with a single flat panel light at the transmitting end and a smartphone with a camera at the receiving end, to achieve fuzzy positioning. The paper further uses the angle sensor to assist in designing the “pseudo-two-light positioning” algorithm and selects 16 test points for experiments, and the average positioning error can reach a minimum of 6.5023 cm, achieving centimeter-level positioning accuracy requirements. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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12 pages, 2316 KiB

Open AccessArticle

Design of Zoom Optical System from Visible to NIR-II for Vivo Fluorescence Imaging Device

by Shuaicheng Guo, Lu Fang and Fuchun Chen

Appl. Sci. 2023, 13(3), 1421; https://doi.org/10.3390/app13031421 - 20 Jan 2023

Cited by 2 | Viewed by 1632

Abstract

Macro vivo fluorescence imaging is becoming more and more important in the medical field. It is also necessary to design the optical design system for the visible light of the NIR-II detector. This paper discusses the design method of the wide spectrum achromatic [...] Read more.

Macro vivo fluorescence imaging is becoming more and more important in the medical field. It is also necessary to design the optical design system for the visible light of the NIR-II detector. This paper discusses the design method of the wide spectrum achromatic optical system from visible light to NIR-II. Based on ZEMAX, a wide spectrum zoom system is designed to freely observe experimental targets in the fields of view of 3.1–18.6°. The four components layout was adopted by the wide spectrum zoom system, which is suitable for 8.2 mm (1/2 inch) CCD, with an f-number of 5.0~6.0, zoom range of 25 mm~150 mm, working spectral band of 400 nm~1700 nm, full field MTF ≥ 0.3 at the spatial frequency of 100 lp/mm, and the maximum distortion of ≤±3%. All optical elements adopt the standard spherical, which can correct all kinds of aberrations well and meet each part’s basic processing requirements. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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24 pages, 21703 KiB

Open AccessArticle

Experimental Evaluation of Display Field Communication Based on Machine Learning and Modem Design

by Yu-Jeong Kim, Pankaj Singh and Sung-Yoon Jung

Appl. Sci. 2022, 12(23), 12226; https://doi.org/10.3390/app122312226 - 29 Nov 2022

Cited by 5 | Viewed by 1482

Abstract

Display field communication (DFC) is a frequency-domain unobtrusive display-to-camera (D2C) communication, in which an electronic display serves as a transmitter and a camera serves as a receiver. In this paper, we propose a machine learning-based DFC scheme and evaluate its performance in a [...] Read more.

Display field communication (DFC) is a frequency-domain unobtrusive display-to-camera (D2C) communication, in which an electronic display serves as a transmitter and a camera serves as a receiver. In this paper, we propose a machine learning-based DFC scheme and evaluate its performance in a lab test scenario. First of all, we adopt the Discrete Cosine Transform (DCT) to transform a spatial-domain image into its spectral-domain equivalent. To reduce the computational complexity during the data-embedding process, addition allocation and subtraction data retrieval techniques are used. Moreover, channel coding is applied to overcome the data error caused by the optical wireless channel. In particular, robust turbo coding is used for error detection and correction. Afterward, we perform the experiments to validate the performance of the proposed system. After capturing the displayed image with a camera, data restoration is done using a deep learning technique. Extensive real-world experiments were performed considering various geometric distortions, noise, and different standard input images. As a result, we found that by increasing the transmit display image size (upsampling), the overall error rate can be reduced. In addition, real-world noise analysis is performed and it is notified that the actual noise is dominant in the low-frequency region of an image. The experimental results confirm the robust performance of the proposed DFC scheme and show that an error-free performance can be achieved up to a distance of 1 m in the given lab test environment setting. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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15 pages, 4867 KiB

Open AccessArticle

DeepCCB-OCC: Deep Learning-Driven Complementary Color Barcode-Based Optical Camera Communications

by Min Tae Kim and Byung Wook Kim

Appl. Sci. 2022, 12(21), 11239; https://doi.org/10.3390/app122111239 - 6 Nov 2022

Cited by 2 | Viewed by 1380

Abstract

Display-to-camera (D2C) communications has emerged as a key method for next-generation videos that offer side information to camera-equipped devices during normal viewing. This paper presents Deep learning-driven Complementary Color Barcode-based Optical Camera Communications (DeepCCB-OCC), a D2C system using multiple deep neural networks built [...] Read more.

Display-to-camera (D2C) communications has emerged as a key method for next-generation videos that offer side information to camera-equipped devices during normal viewing. This paper presents Deep learning-driven Complementary Color Barcode-based Optical Camera Communications (DeepCCB-OCC), a D2C system using multiple deep neural networks built for imperceptible transmission and reliable communication in a D2C link. DeepCCB-OCC takes advantage of a the You Only Look Once (YOLO) model to provide seamless detection of a color barcode area in electronic displays. To identify transmitted color barcode symbols in the received image, we define various color barcode patterns caused by the synchronization jitter between the camera and the display. Then, DeepCCB-OCC incorporates convolutional neural network (CNN) models to accurately detect the pilot and data symbols in the transmission packets, regardless of the various D2C environments. Experiments with a commercial monitor and a smartphone demonstrate that DeepCCB-OCC outperforms the conventional CCB-OCC system from various distances and angles of a D2C link. The experiment results prove that, when the alignment angle was 20 degrees at a distance of 90 cm between the display and the camera, the proposed scheme achieved approximately 79.1 bps, which showed a performance improvement of 14.1% compared to the existing technique. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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17 pages, 6359 KiB

Open AccessArticle

Atmospheric Effects on Satellite–Ground Free Space Uplink and Downlink Optical Transmissions

by Nilesh Maharjan, Nikesh Devkota and Byung Wook Kim

Appl. Sci. 2022, 12(21), 10944; https://doi.org/10.3390/app122110944 - 28 Oct 2022

Cited by 12 | Viewed by 4050

Abstract

Free space optical (FSO) communications have the potential to be one of the most essential technologies for solving the high-bandwidth demands of communications between satellites and ground stations. In this study, we examine the impact of the atmosphere on satellite–ground FSO uplink and [...] Read more.

Free space optical (FSO) communications have the potential to be one of the most essential technologies for solving the high-bandwidth demands of communications between satellites and ground stations. In this study, we examine the impact of the atmosphere on satellite–ground FSO uplink and downlink communications. To consider diverse atmospheric conditions on both uplink and downlink, we derive FSO channel elements such as the fog attenuation coefficient, refractive index parameter, coherence length, turbulence model, and angle-of-arrival fluctuation. Unlike conventional work, we provide FSO channel analysis based on variations in the Fried parameter, zenith angle, scintillation index, and Rytov variance. Using simulation results from the optical settings, we examine the influence on channel performance of conditions such as atmospheric attenuation and intensity fluctuation. Based on this examination, we determine that 1550 nm is the preferred wavelength for both uplink and downlink FSO channels to mitigate the impact of turbulence and that larger receiver apertures lessen angle-of-arrival changes. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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18 pages, 1599 KiB

Open AccessArticle

Quantum-Chromodynamics-Inspired 2D Multicolor LED Matrix to Camera Communication for User-Centric MIMO

by Geetha Vasantha and Sanket Salvi

Appl. Sci. 2022, 12(20), 10204; https://doi.org/10.3390/app122010204 - 11 Oct 2022

Cited by 1 | Viewed by 1604

Abstract

With the high availability of low-cost and energy-efficient LEDs and cameras, there is increased interest in optical camera communication (OCC) to provide nonradio-frequency-based communication solutions in the domains of advertisement, vehicular communication, and the Internet of Things (IoT). As per the IEEE 802.15.7-2018 [...] Read more.

With the high availability of low-cost and energy-efficient LEDs and cameras, there is increased interest in optical camera communication (OCC) to provide nonradio-frequency-based communication solutions in the domains of advertisement, vehicular communication, and the Internet of Things (IoT). As per the IEEE 802.15.7-2018 standard, new physical-layer clauses support low-frame-rate camera communication with allowable flickering. This paper proposes an OCC system that can provide user-centric multiple-input multiple-output (MIMO) loosely based on quantum-chromodynamics (QCD) concepts. A QCD–OCC simulator and prototype are proposed, implemented, and evaluated on the basis of the pixel intensity profile, peak signal-to-noise ratio (PSNR), the success of reception (%), bit-error rate (BER), and throughput under different ambient lighting conditions and distances. We observed 100% and 84% success of reception using the proposed prototype and simulator, respectively, for the data rate of 720 bps. The maximal tolerable BER of

1.13 \times 10^{- 2}

for IoT applications was observed at a maximal distance of 200 cm and a maximal data rate of 3600 bps. The proposed system was also compared with other existing OCC systems with similar hardware and implementation requirements. The proposed QCD–OCC system provided rotation support up to 90 degrees and throughput of 4.32 kbps for a 30 fps camera. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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17 pages, 3100 KiB

Open AccessArticle

A General Calibration Method for Dual-PTZ Cameras Based on Feedback Parameters

by Kang Mao, Youchun Xu, Rendong Wang and Shiju Pan

Appl. Sci. 2022, 12(18), 9148; https://doi.org/10.3390/app12189148 - 12 Sep 2022

Cited by 1 | Viewed by 2117

Abstract

With the increasing application of dual-PTZ (Pan-Tilt-Zoom) cameras in intelligent unmanned systems, research regarding their calibration methods is becoming more and more important. The intrinsic and extrinsic parameters of dual-PTZ cameras continuously change during rotation and zoom, resulting in difficulties in obtaining precise [...] Read more.

With the increasing application of dual-PTZ (Pan-Tilt-Zoom) cameras in intelligent unmanned systems, research regarding their calibration methods is becoming more and more important. The intrinsic and extrinsic parameters of dual-PTZ cameras continuously change during rotation and zoom, resulting in difficulties in obtaining precise calibration. Here, we propose a general calibration method for dual-PTZ cameras with variable focal length and posture under the following conditions: the optical center of the camera does not coincide with the horizontal and pitch rotation axes, and the horizontal and pitch rotation axes are not perpendicular to each other. We establish a relationship between the intrinsic and extrinsic parameters and the feedback parameters (pan, tilt, zoom value) of dual-PTZ cameras by fitting and calculating previous calibration results acquired at specific angles and zoom values using Zhang’s calibration method. Subsequently, we derive the intrinsic and extrinsic parameter calculation formula at arbitrary focal length and posture based on the camera’s feedback parameters. The experimental results show that intrinsic and extrinsic parameters computed using the proposed method can better meet precision requirements compared with the ground truth calibrated using Zhang’s method. The average focal length error is less than 4%, the cosine similarity of the rotation matrix between the left and right cameras is more than 99.8%, the translation vector error is less than 1%, and the recalculated Euler angle errors are less than 1 degree. Our work can quickly and accurately obtain intrinsic and extrinsic parameters during the use of the dual-PTZ camera. Full article

(This article belongs to the Special Issue Optical Camera Communications and Applications)

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