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Free Space Ground to Satellite Optical Communications Using Kramers–Kronig Transceiver in the Presence of Atmospheric Turbulence. SENSORS 2022; 22:s22093435. [PMID: 35591125 PMCID: PMC9105684 DOI: 10.3390/s22093435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/24/2022] [Accepted: 04/28/2022] [Indexed: 02/04/2023]
Abstract
Coherent detection provides the optimum performance for free space optical (FSO) communication systems. However, such detection systems are expensive and require digital phase noise compensation. In this paper, the transmission performance of long-haul FSO system for ground-to-satellite communication based on a Kramers–Kronig (KK) transceiver is evaluated. KK transceivers utilize inexpensive direct detection receivers and the signal phase is retrieved from the received current using the well-known KK relations. KK transceivers are not sensitive to the laser phase noise and, hence, inexpensive lasers with large linewidths can be used at the transmitter. The transmission performance of coherent and KK transceivers is compared in various scenarios such as satellite-to-ground, satellite-to-satellite, and ground-to-satellite for weak, moderate, and strong turbulence. The results show that the transmission performance of a system based on the KK transceiver is comparable to that based on a coherent transceiver, but at a significantly lower system cost and complexity. It is shown that in the absence of turbulence, the coherent receiver has a ~3 dB performance advantage over the KK receiver. However, in the presence of strong turbulence, this performance advantage becomes negligible.
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Matus V, Guerra V, Jurado-Verdu C, Zvanovec S, Perez-Jimenez R. Wireless Sensor Networks Using Sub-Pixel Optical Camera Communications: Advances in Experimental Channel Evaluation. SENSORS 2021; 21:s21082739. [PMID: 33924508 PMCID: PMC8069996 DOI: 10.3390/s21082739] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 11/16/2022]
Abstract
Optical wireless communications in outdoor scenarios are challenged by uncontrollable atmospheric conditions that impair the channel quality. In this paper, different optical camera communications (OCC) equipment are experimentally studied in the laboratory and the field, and a sub-pixel architecture is raised as a potential solution for outdoor wireless sensor networks (WSN) applications, considering its achievable data throughput, the spatial division of sources, and the ability of cameras to overcome the attenuation caused by different atmospheric conditions such as rain, turbulence and the presence of aerosols. Sub-pixel OCC shows particularly adequate capabilities for some of the WSN applications presented, also in terms of cost-effectiveness and scalability. The novel topology of sub-pixel projection of multiple transmitters over the receiver using small optical devices is presented as a solution using OCC that re-uses camera equipment for communication purposes on top of video-monitoring.
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Affiliation(s)
- Vicente Matus
- Institute for Technological Development and Innovation in Communications (IDeTIC), University of Las Palmas de Gran Canaria, 35001 Las Palmas, Spain; (V.G.); (C.J.-V.); (R.P.-J.)
- Correspondence:
| | - Victor Guerra
- Institute for Technological Development and Innovation in Communications (IDeTIC), University of Las Palmas de Gran Canaria, 35001 Las Palmas, Spain; (V.G.); (C.J.-V.); (R.P.-J.)
| | - Cristo Jurado-Verdu
- Institute for Technological Development and Innovation in Communications (IDeTIC), University of Las Palmas de Gran Canaria, 35001 Las Palmas, Spain; (V.G.); (C.J.-V.); (R.P.-J.)
| | - Stanislav Zvanovec
- Department of Electromagnetic Field, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka, 16627 Prague, Czech Republic;
| | - Rafael Perez-Jimenez
- Institute for Technological Development and Innovation in Communications (IDeTIC), University of Las Palmas de Gran Canaria, 35001 Las Palmas, Spain; (V.G.); (C.J.-V.); (R.P.-J.)
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Matus V, Guerra V, Zvanovec S, Rabadan J, Perez-Jimenez R. Sandstorm effect on experimental optical camera communication. APPLIED OPTICS 2021; 60:75-82. [PMID: 33362076 DOI: 10.1364/ao.405952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
Sandstorms can severely affect the reliability of outdoor optical wireless communications (OWC) by diminishing large regions' visibility. In this work, the effect of a real sandstorm on optical camera communications (OCC) links is experimentally evaluated. Two link ranges are essayed using a cost-efficient telescope-based camera setup with commercial LEDs. Using on-off keying modulation, a data rate of 1035 and 630 bps with error probabilities of 9.14⋅10-5 and 4.1⋅10-3 for 100 m and 200 m, respectively, can be achieved. The signal-to-noise ratio of the links was optimized by tuning the analog amplifier's gain of the camera, increasing it by up to 9 dB. It is shown that scattering due to the sandstorm can even be beneficial for increasing the data rate in OCC (contrary to classical photodetector-based OWC links), thanks to an increment of 33% on the region of interest dimensions compared to the expected clear air link.
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Sun X, Zou D, Qu Z, Djordjevic IB. Run-time reconfigurable adaptive LDPC coding for optical channels. OPTICS EXPRESS 2018; 26:29319-29329. [PMID: 30470097 DOI: 10.1364/oe.26.029319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/16/2018] [Indexed: 06/09/2023]
Abstract
In this paper, we proposed a class of large-girth QC-LDPC codes designed to maximize the girth property with code rates ranging from 0.5 to 0.8, which leads to well-structured parity-check matrix and generator matrix. Instead of implementing several FEC encoder and decoder engines in hardware, we design an efficient unified FPGA-based architecture enabling run-time reconfigurable capability. Apart from four principle LDPC codes being incorporated into a unified design, shortening is adopted to bridge the rate gap between principle codes. With our proposed unified LDPC engine, the signal-to-noise ratio (SNR) limits of -1 dB to 2.2 dB have been demonstrated at BER of 10-12 in additive white Gaussian noise (AWGN) channel by FPGA emulation. It is desirable for the application to both free-space optical (FSO) and fiber optics communications. Large code rate range is preferred to deal with various channel impairments. To further verify the proposed unified code engine for FSO applications, we tested the scheme through a spatial light modulator (SLM)-based FSO channel emulator. We showed that in medium atmospheric turbulence regime, a post-FEC BER below 10-8 can be achieved without any interleaver and adaptive optics.
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Mahalati RN, Kahn JM. Effect of fog on free-space optical links employing imaging receivers. OPTICS EXPRESS 2012; 20:1649-1661. [PMID: 22274507 DOI: 10.1364/oe.20.001649] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We analyze free-space optical links employing imaging receivers in the presence of misalignment and atmospheric effects, such as haze, fog or rain. We present a detailed propagation model based on the radiative transfer equation. We also compare the relative importance of two mechanisms by which these effects degrade link performance: signal attenuation and image blooming. We show that image blooming dominates over attenuation, except under medium-to-heavy fog conditions.
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Affiliation(s)
- Reza Nasiri Mahalati
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
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Drost RJ, Moore TJ, Sadler BM. UV communications channel modeling incorporating multiple scattering interactions. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2011; 28:686-695. [PMID: 21478967 DOI: 10.1364/josaa.28.000686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In large part because of advancements in the design and fabrication of UV LEDs, photodetectors, and filters, significant research interest has recently been focused on non-line-of-sight UV communication systems. This research in, for example, system design and performance prediction, can be greatly aided by accurate channel models that allow for the reproducibility of results, thus facilitating the fair and consistent comparison of different communication approaches. In this paper, we provide a comprehensive derivation of a multiple-scattering Monte Carlo UV channel model, addressing weaknesses in previous treatments. The resulting model can be used to study the contribution of different orders of scattering to the path loss and impulse response functions associated with general UV communication system geometries. Simulation results are provided that demonstrate the benefit of this approach.
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Affiliation(s)
- Robert J Drost
- United States Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA.
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Kedar D, Arnon S. Non-line-of-sight optical wireless sensor network operating in multiscattering channel. APPLIED OPTICS 2006; 45:8454-61. [PMID: 17086255 DOI: 10.1364/ao.45.008454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Networks of sensors are envisaged to be major participants in future data-gathering systems for civilian and military applications, including medical and environmental monitoring and surveillance, home security, agriculture, and industry. Typically, a very large number of miniature sensing and communicating nodes are distributed ad hoc at the location of interest, where they establish a network and wirelessly communicate sensed data either to one another or to a base station using various network topologies. The optical modality is a potential solution for the links, due to the small and lightweight hardware and low power consumption, as well as other special features. Notably, the backscattering of light by molecules and aerosols in the atmosphere can function as a vehicle of communication in a way similar to the deployment of numerous tiny reflecting mirrors. The scattering of light at solar-blind ultraviolet wavelengths is of particular interest since scattering by atmospheric particles is significant and ambient solar interference is minimal. In this paper we derive a mathematical model of a simple and low-cost non-line-of-sight (NLOS) optical wireless sensor network operating in the solar-blind ultraviolet spectral range. The viability and limitations of the internode link are evaluated and found to facilitate miniature operational sensor networks.
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Affiliation(s)
- Debbie Kedar
- Satellite and Wireless Communication Laboratory, Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, IL-84105 Beer-Sheva, Israel
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Kedar D, Arnon S. Evaluation of coherence interference in optical wireless communication through multiscattering channels. APPLIED OPTICS 2006; 45:3263-9. [PMID: 16676030 DOI: 10.1364/ao.45.003263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Optical wireless communication has been the subject of much research in recent years because of the increasing interest in laser satellite-ground links and urban optical wireless communication. The major sources of performance degradation have been identified as the spatial, angular, and temporal spread of the propagating beam when the propagation channel is multiscattering, resulting in reduced power reception and intersignal interference, as well as turbulence-induced scintillations and noise due to receiver circuitry and background illumination. However, coherence effects due to multipath interference caused by a scattering propagation channel do not appear to have been treated in detail in the scientific literature. We attempt a theoretical analysis of coherence interference in optical wireless communication through scattering channels and try to quantify the resultant performance degradation for different media. We conclude that coherence interference is discernible in optical wireless communication through scattering channels and is highly dependent on the microscopic nature of the propagation medium.
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Affiliation(s)
- Debbie Kedar
- Satellite and Wireless Communication Laboratory, Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Aharonovich M, Arnon S. Performance improvement of optical wireless communication through fog with a decision feedback equalizer. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2005; 22:1646-54. [PMID: 16134862 DOI: 10.1364/josaa.22.001646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Optical wireless communication (OWC) systems use the atmosphere as a propagation medium. However, a common problem is that from time to time moderate cloud and fog emerge between the receiver and the transmitter. These adverse weather conditions impose temporal broadening and power loss on the optical signal, which reduces the digital signal-to-noise ratio (DSNR), produces significant intersymbol interference (ISI), and degrades the communication system's bit error rate (BER) and throughput. We propose and investigate the use of a combined adaptive bandwidth mechanism and decision feedback equalizer (DFE) to mitigate these atmospheric multipath effects. Based on theoretical analysis and simulations of DSNR penalties, BER, and optimum system bandwidths, we show that a DFE improves the outdoor OWC system immunity to ISI in foggy weather while maintaining high throughput and desired low BER.
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Affiliation(s)
- Marius Aharonovich
- Satellite and Wireless Communication Laboratory, Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, PO. Box 653, IL-84105, Beer-Sheva, Israel
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