scholarly journals Serial DF Relayed FSO Links over Mixture Gamma Turbulence Channels and Nonzero Boresight Spatial Jitter

Computation ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 34 ◽  
Author(s):  
Androutsos ◽  
Nistazakis ◽  
Khalid ◽  
Muhammad ◽  
Tombras
Keyword(s):  
Communication Systems ◽  
Optical Signal ◽  
Propagation Path ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Decode And Forward ◽  
Pointing Error ◽  
Composite Channels ◽  
Turbulence Effects ◽  
Significant Phenomenon

Over the past few years, terrestrial free space optical (FSO) communication systems have demonstrated increasing research and commercial interest. However, due the signal’s propagation path, the operation of FSO links depends strongly on atmospheric conditions and related phenomena. One such significant phenomenon is the scintillation caused by atmospheric turbulence effects; in order to address the significant performance degradation that this causes, several statistical models have been proposed. Here, turbulence-induced fading of the received optical signal is investigated through the recently presented mixture Gamma distribution, which accurately describes the irradiance fluctuations at the receiver’s input of the FSO link. Additionally, at the same time, it significantly reduces the mathematical complexity of the expressions used for the description of composite channels with turbulence along with nonzero boresight pointing error-induced fading. In order to counterbalance the performance mitigation due to these effects, serial decode-and-forward relays are employed, and the performance of the system is estimated through derived mathematical expressions.

scholarly journals Performance Investigation of OFDM-FSO System under Diverse Weather Conditions of Bangladesh

2018 ◽  
Vol 8 (5) ◽  
pp. 3722
Author(s):  
Maliha Sultana ◽  
Agnila Barua ◽  
Jobaida Akhtar ◽  
Mohammad Istiaque Reja
Keyword(s):  
Atmospheric Turbulence ◽  
Communication Systems ◽  
Weather Conditions ◽  
Index Structure ◽  
Propagation Path ◽  
Free Space Optical ◽  
Atmospheric Attenuation ◽  
Suitable Alternative ◽  
Pointing Error ◽  
Free Spectrum

Free space optical (FSO) communication systems which are deployed for last mile access, being considered as a suitable alternative technology for optical fiber networks. It is one of the emerging technologies for broadband wireless connectivity which has also been receiving growing attention due to high data rate transmission capability with low installation cost and license free spectrum. However, the widespread use of FSO technology has been hampered by the randomly time varying characteristics of propagation path mainly due to atmospheric turbulence, sensitivity to diverse weather conditions and the nonlinear responsivity of laser diode. This paper presents the performance investigation of an OFDM-FSO system over atmospheric turbulence channels under diverse weather conditions of Bangladesh. The channel is modeled with gamma-gamma distribution using 16-QAM modulation format and 4×4 multiple transceiver FSO system. All possible challenges are imposed on the system performance such as atmospheric attenuation, turbulence, pointing error, geometric loss etc. The refractive index structure parameter and atmospheric attenuation coefficient for different weather conditions are calculated by using the data, collected from Bangladesh Meteorological Department. The acquired results can be fruitful for scheming, forecasting and assessing the OFDM-FSO system’s ability to transmit wireless services over turbulent FSO links under actual conditions of Bangladesh.

Performance Investigation of FSO–OFDM Communication Systems under the Heavy Rain Weather

2017 ◽  
Vol 39 (1) ◽  
Author(s):  
Florence Rashidi ◽  
Jing He ◽  
Lin Chen
Keyword(s):  
Communication System ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Attenuation Factor ◽  
Heavy Rain ◽  
Rain Attenuation ◽  
Optical Signal ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Rainfall Condition

AbstractThe challenge in the free-space optical (FSO) communication is the propagation of optical signal through different atmospheric conditions such as rain, snow and fog. In this paper, an orthogonal frequency-division multiplexing technique (OFDM) is proposed in the FSO communication system. Meanwhile, considering the rain attenuation models based on Marshal & Palmer and Carbonneau models, the performance of FSO communication system based on the OFDM is evaluated under the heavy-rain condition in Changsha, China. The simulation results show that, under a heavy-rainfall condition of 106.18 mm/h, with an attenuation factor of 7 dB/km based on the Marshal & Palmer model, the bit rate of 2.5 and 4.0 Gbps data can be transmitted over the FSO channels of 1.6 and 1.3 km, respectively, and the bit error rate of less than 1E − 4 can be achieved. In addition, the effect on rain attenuation over the FSO communication system based on the Marshal & Palmer model is less than that of the Carbonneau model.

scholarly journals Energy Optimization of a Laser-Powered Hovering-UAV Relay in Optical Wireless Backhaul

2021 ◽  
Author(s):  
Muhammad Salman Bashir ◽  
Mohamed-Slim Alouini
Keyword(s):  
Quality Of Service ◽  
Communication Systems ◽  
Low Cost ◽  
Base Stations ◽  
Achievable Rate ◽  
Optical Wireless ◽  
Free Space Optical ◽  
Decode And Forward ◽  
Wireless Backhaul

<div>Due to their flexibility and low cost deployment, unmanned aerial vehicles (UAV) will most likely act as base stations and backhaul relays in the next generation of wireless communication systems. However, these UAVs---in the untethered mode---can only operate for a finite time due to limited energy they carry in their batteries. In free-space optical communications, one solution is to transport both the data and the energy from the source to the UAV through the laser beam---a concept known as <i>simultaneous lightwave information and power transfer</i> (SLIPT). In this study, we have analyzed the SLIPT scheme for laser-powered decode-and-forward UAV relays in an optical wireless backhaul. The major goal of this study is to optimally allocate the received beam energy between the decoding circuit, the transmitting circuit and the rotor block of the relay in order to maximize a quality-of-service metric such as maximum achievable rate, outage or error probabilities. As expected, we note that the optimal power allocation depends heavily on the source-relay and relay-destination channel conditions. In the final part of this study, we have maximized the operational time of the UAV relay given that the maximum achievable rate stays above a certain threshold in order to meet a minimum quality-of-service requirement.</div>

scholarly journals Fog and Rain Attenuation Characterization and Performance of Terrestrial Free Space Optical Communication in Akure, Nigeria

2019 ◽  
Vol 4 (3) ◽  
pp. 125-134
Author(s):  
Joseph Sunday Ojo ◽  
Owolawi P. A. ◽  
Ajewole M. O. ◽  
Adetunji R. M.
Keyword(s):  
Free Space ◽  
Communication Systems ◽  
Outer Space ◽  
Rain Attenuation ◽  
Integration Time ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
High Data ◽  
Space Optical Communication ◽  
And Performance

 Reliable broadband communication requires secure high data rate and bandwidth links. With the observed increase in broadband users, known communication systems such as RF and microwave links cannot promise such requirements due to link interference and low bandwidth. A current communication system that promises such requirements and more is Free Space Optical (FSO) communication. This system basically involves the transmission of signal-modulated optical radiation from a transmitter to a receiver through the atmosphere or outer space. However, location-variant atmospheric channel degrades the performance of an FSO system under severe atmospheric conditions, thus necessitating local atmospheric attenuation studies. This paper presents the characterization of both fog- and rain-induced attenuation and the performance of an FSO system in a terrestrial terrain at Akure, Nigeria. One-year archived visibility data and in-situ measured 1-minute integration time rain rate data obtained from Nigerian Meteorological Agency (NIMET) and the Department of Physics, Federal University of Technology, Akure were used to compute the fog- and rain-induced specific attenuations using Kruse model and Carboneur model respectively. The performance of the FSO system is analyzed through link margin by using the parameters of a commercial optical transceiver, Terescope 5000.

scholarly journals Impact of pointing error on SISO/MISO drones swarm-based free space optical system in weak turbulence regime

2021 ◽  
Vol 23 (2) ◽  
pp. 918
Author(s):  
Abdullah Jameel Mahdi ◽  
Wamidh Jalil Mazher ◽  
Osman Nuri Ucan
Keyword(s):  
Free Space ◽  
Communication Systems ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Weather Conditions ◽  
Free Space Optical ◽  
Single Input Single Output ◽  
Pointing Error ◽  
Single Output ◽  
Link Distance

<p>Applying the drone-based free space optical (FSO) technology is recent in communication systems. The FSO technology hashigh-security features dueto narrow beamwidth, insusceptible to interferences, free license and landline connection is not appropriate. However, these advantages face many obstacles that affect the system's performance, such as random weather conditions and misalignment. The pointing error Hpis one of the critical factors of the channel gain H. The related parameters of the Hp factor: the pointing error angles θr and the path length Z, were manipulated to extract the applicable values at various receiver diameter values. The proposed system has two topologies: single input single output (SISO) and multiple input single output (MISO), flying in weak atmospheric turbulence. The simulation was done using MATLAB software 2020. The average bit error rate (ABER) for the system versus signal-to-noise ratio (SNR) were verified and analyzed. The results showed that at θr=10<sup>−3</sup>rad, Z increased in the range 10~100m for each one-centimeter increase of DR. At θr=10<sup>−2</sup>rad, the applicable Z was nearly 10% of the link distance Z when θr=10<sup>−3</sup>rad was applied. Consequently, an increase in θr must correspond decrease in Z and vice versa to maintain the system at high performance.</p>

scholarly journals Investigations of Free Space Optical Communications Under Real-World Atmospheric Conditions

2020 ◽  
Vol 116 (1) ◽  
pp. 475-490 ◽  
Author(s):  
Tobias Siegel ◽  
Shun-Ping Chen
Keyword(s):  
Optical Communications ◽  
Free Space ◽  
Communication Systems ◽  
New Technologies ◽  
Weather Conditions ◽  
Optical Systems ◽  
Limiting Factors ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Atmospheric Channel

AbstractDue to the increasing demand for higher bandwidth in modern communication systems, conventional networks are continuously expanded with new technologies to improve coverage. Free space optical communications (FSOC) shows some significant advantages concerning system setup time in comparison with the classical fiber optical systems on one hand, substantial spectral bandwidth and performances in comparison with the wireless systems under certain conditions on the other hand. This makes this technology not only a reasonable extension for metropolitan area networks but also provides the capability to set up a network after an outage in case of natural disaster quickly. But transmitting data by using FSOC involves some limiting factors that have to be considered prior to each installation. Since the atmospheric channel is not static, the influence of changing weather conditions or industrial smog have a significant impact on the available bitrate. A simulation platform is developed and presented in this paper for investigation of FSOC considering these circumstances. Regarding the atmospheric channel, turbulence, distance-dependent beam divergence, and applied modulation schemes, a general overview of the capabilities is presented and discussed. The insight of this paper should help to make a decision under which preconditions either the FSOC provides a meaningful application possibility, or the limiting factors become too crucial and other technologies must be considered.

scholarly journals From Mirrors to Free-Space Optical Communication—Historical Aspects in Data Transmission

2020 ◽  
Vol 12 (11) ◽  
pp. 179
Author(s):  
Magdalena Garlinska ◽  
Agnieszka Pregowska ◽  
Karol Masztalerz ◽  
Magdalena Osial
Keyword(s):  
Optical Communication ◽  
Data Transmission ◽  
Free Space ◽  
Communication Systems ◽  
High Speed ◽  
Rapid Development ◽  
Free Space Optical Communication ◽  
Atmospheric Conditions ◽  
Free Space Optical ◽  
Space Optical Communication

Fast communication is of high importance. Recently, increased data demand and crowded radio frequency spectrum have become crucial issues. Free-Space Optical Communication (FSOC) has diametrically changed the way people exchange information. As an alternative to wire communication systems, it allows efficient voice, video, and data transmission using a medium like air. Due to its large bandwidth, FSOC can be used in various applications and has therefore become an important part of our everyday life. The main advantages of FSOC are a high speed, cost savings, compact structures, low power, energy efficiency, a maximal transfer capacity, and applicability. The rapid development of the high-speed connection technology allows one to reduce the repair downtime and gives the ability to quickly establish a backup network in an emergency. Unfortunately, FSOC is susceptible to disruption due to atmospheric conditions or direct sunlight. Here, we briefly discuss Free-Space Optical Communication from mirrors and optical telegraphs to modern wireless systems and outline the future development directions of optical communication.

scholarly journals Performance Assessment of Channel Capacity of Co-operative Communication based System over Dual-hop Asymmetric RF/FSO system

2020 ◽  
Vol 9 (4) ◽  
pp. 439-442
Keyword(s):  
Channel Capacity ◽  
Communication Systems ◽  
Distribution Channel ◽  
Relay Node ◽  
Simulation Method ◽  
Destination Node ◽  
Free Space Optical ◽  
Decode And Forward ◽  
Analytical Expressions

Cooperative Communication Systems and Relay Selection approaches are recent techniques of wireless communication system that enhance the quality of service (QoS). This research paper probes the execution of the Radio-Frequency and Free Space Optical (RF/FSO) Co-operative system using network of relays. The Co-operative relay system is typically composed of node of a source, the nodes of relays and node of a destination. The source and relay link (S-R link) follow the Generalized-K Fading distribution channel. The link connecting the relay node/device and the destination (R-D link) follows - Fading distribution channel. The relay is considered to adopt according to DF i.e Decode and Forward method of relaying and cooperatively assists in transmission to the destination node from the source node. The channel capacity is modelled using PDF (Probability Density Function) for the - distribution channel of fading for evaluation of the Dual-hop Asymmetric RF-FSO system. The performance and the analytical expressions of the new system proposed i.e. RF/FSO system were verified and validated using Monte Carlo simulation method

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