Laser communication between satellites in the constellation and from the satellites to ground stations offers a gigantic data rate for the users. This principal advantage drives telecom companies to develop this technology to use it like a carrier signal, the most disadvantage of this technology is the need to very complicated pointing systems between the transmitter and the receiver due to a very small beam divergence, continually moving of satellites in orbits and the distance between the satellites (tens of thousands of kilometers). The laser beam suffers continuously from several factors like atmospheric turbulences, internal and external vibrations. All these factors lead to an increase in the bit errors rate and cause degradation in the communication quality. This paper deals with a new method of modelisation of external effects in transmission of signal light from a ground station to the satellite through atmospheric disturbances. Indeed, an in-depth investigation, of the influences of satellite vibrationsinlaser signal transmission between satellites constellation, has been conducted by studying the effect of the intensity of vibrations on the optical signal amplitude. Some solutions are proposed to improve the efficiency of optical satellites communications.
International Journal of Business and Management Invention (IJBMI) is an international journal intended for professionals and researchers in all fields of Business and Management. IJBMI publishes research articles and reviews within the whole field Business and Management, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Nowadays, there has been an increase and dependent items that affect the quality of the signals
such as the properties of substances in the buildings, objects and humans’ movements, electronic equipment. In
this study, the effects of electromagnetic interference on the functional usage of mobile communications are
examined. The indoor and outdoor attenuation characteristics of 2G, 3G and 4G frequency bands are
investigated. Field strength measurements are conducted in university campusopenarea, along a corridorfield
in a fivestoreyuniversitybuilding, in different floors, and rooms, where normal incidence on plane boundary is of
main concern. This study investigates multilayer model for building structures. The evaluation of measured
values together with the simulated results is compared with literature outcomes. In addition, dependency with
the frequency, power of the waves and existence of trees on the transmission path are also discussed.
This document discusses methods for reducing coupling between antennas located near each other. It focuses on using periodic structures, such as corrugated metal surfaces, to provide electromagnetic shielding between antennas. Periodic structures can give the surface an inductive or capacitive impedance that attenuates electromagnetic fields and reduces coupling. Structures with quarter-wavelength deep slots can reflect plane waves with no phase reversal, further reducing coupling. While useful, periodic structures work best at wavelengths much smaller than the period. More research is still needed to develop new designs and models to improve electromagnetic compatibility between antennas.
Analysis and simulations of optimal geometry shapes of the 4 and 9 nano hole ...IJECEIAES
The possibility to limit and manipulate photons at nanometer scales attracted a lot of interest for exciting applications from subwavelength in laser, biosensors, biomedical and optoelectronics devices, the sensor optical properties, however; are complex due to two resonances through propagating and localized surface plasmons. The optical properties of surface plasmons (SPs) at the resonant wavelength is depending on the geometrical nanostructure of materials. In this article, we used different geometry of nanoholes array, 4 and 9 nanoholes array in a metallic film gold nanoparticle with different thickness (20,50,100) nm on SiO2 substrate with refractive index 1.46, we designed two different geometries; 4- holes: hole radius r1=200 nm, period p1=600 nm; and 9- holes: r2=100 nm, period p2=300 nm. Transmission and reflection spectrum have been calculated and simulated by FDTD Lumerical program. From results are observed the effect of thickness is interesting, transmission is increased at (t=20nm) for two arrays. Furthermore, the number of hole and its area has an influence on optical transmission and other parameters (E, H, Ref) which are characteristics of design of metallic nanostructure. We can see that there is a peak value of the wavelength at 519 nm approximately to 73% strong light transmission with 4-NHA in the other hand wavelength of 519 nm transmission is 45% with 9-NHA. strong light transmission is hopeful for many applications (biomedical devices, nanoantennas and laser optical fiber).
This document provides a review of recent research on exciting surface plasmon polaritons (SPPs) in the microwave and terahertz regimes using subwavelength patterns on metal surfaces. Key challenges in high-speed electronics like bandwidth, size, losses, and signal integrity can be addressed using spoof SPP structures. Such structures mimic the properties of natural SPPs and allow controlling the propagation of electromagnetic waves at lower frequencies. Various applications in chemical sensing, imaging, and communication have benefited from exciting SPPs in these frequency ranges. The document discusses the theoretical background and properties of SPPs and reviews research on different spoof SPP waveguide designs.
This senior design project report describes the design of a microstrip antenna to operate at multiple frequency bands for GSM, Wi-Fi, and GPS. The report includes an introduction to basic antenna theory and properties. It discusses the design objectives of achieving multi-band operation. Software simulations were used to design and optimize a rectangular patch geometry microstrip antenna. The antenna was then manufactured and test results were presented that showed operation at desired frequency bands. The project demonstrated the feasibility of integrating wireless applications using a single multiband microstrip antenna design.
MODELLING OF LAND MOBILE SATELLITE CHANNEL TO COUNTER CHANNEL OUTAGE ijdpsjournal
A Land mobile satellite service (LMSS) is an arm of mobile satellite system (MSS), in which a number of
services are its subset. To ensure network availability, high quality of service (QoS), and reduce outage on
the channel as a result of channel interferences during propagation, it is important to understand channel
behaviour in various transmission environments. Vast literature has been published on the subject of
channel models that attempted to improve on impairments in communication links: a large number has
focused on narrowband channels than wideband. Due to advances in recent technology wideband
modelling of satellite channels becomes necessary, which this research study is focused, particularly
model for Land Mobile Satellite (LMS) channel. This study models the complete behaviour of LMS
Channel based on the Lutz’s (1989) two-state statistical model but modified with two-state Markov chain
for two different transmission environments, namely: shadowing (line-of-sight) and un- shadowing (nonline-of-sight)
conditions. In order to reduce the effect of channel outages, satellite diversity approach was
employed in addition to the 2-state Markov chain. Simulations of these conditions were performed using
MATLAB programming language. The study concludes that satellite diversity reduces outage on the
channel, and when mobile terminals have access to two geostationary satellites simultaneously network
availability is assured compared to when it has only one satellite link.
Substrate Integrated Waveguide Based Leaky-Wave Antenna IRJET Journal
This document describes a novel leaky-wave antenna design based on a substrate integrated waveguide (SIW) with non-uniform slots. The key aspects are:
1) The antenna uses a SIW structure with slots of varying widths (non-uniform) to reduce side lobes and improve radiation efficiency compared to previous uniform slot designs.
2) Simulation results show the design has improved reflection coefficient (below -10 dB) and scans from broadside to near end-fire as frequency increases from 10.3 GHz to 12 GHz.
3) Radiation patterns at different frequencies within the band demonstrate the beam scanning ability of the design.
International Journal of Business and Management Invention (IJBMI) is an international journal intended for professionals and researchers in all fields of Business and Management. IJBMI publishes research articles and reviews within the whole field Business and Management, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Nowadays, there has been an increase and dependent items that affect the quality of the signals
such as the properties of substances in the buildings, objects and humans’ movements, electronic equipment. In
this study, the effects of electromagnetic interference on the functional usage of mobile communications are
examined. The indoor and outdoor attenuation characteristics of 2G, 3G and 4G frequency bands are
investigated. Field strength measurements are conducted in university campusopenarea, along a corridorfield
in a fivestoreyuniversitybuilding, in different floors, and rooms, where normal incidence on plane boundary is of
main concern. This study investigates multilayer model for building structures. The evaluation of measured
values together with the simulated results is compared with literature outcomes. In addition, dependency with
the frequency, power of the waves and existence of trees on the transmission path are also discussed.
This document discusses methods for reducing coupling between antennas located near each other. It focuses on using periodic structures, such as corrugated metal surfaces, to provide electromagnetic shielding between antennas. Periodic structures can give the surface an inductive or capacitive impedance that attenuates electromagnetic fields and reduces coupling. Structures with quarter-wavelength deep slots can reflect plane waves with no phase reversal, further reducing coupling. While useful, periodic structures work best at wavelengths much smaller than the period. More research is still needed to develop new designs and models to improve electromagnetic compatibility between antennas.
Analysis and simulations of optimal geometry shapes of the 4 and 9 nano hole ...IJECEIAES
The possibility to limit and manipulate photons at nanometer scales attracted a lot of interest for exciting applications from subwavelength in laser, biosensors, biomedical and optoelectronics devices, the sensor optical properties, however; are complex due to two resonances through propagating and localized surface plasmons. The optical properties of surface plasmons (SPs) at the resonant wavelength is depending on the geometrical nanostructure of materials. In this article, we used different geometry of nanoholes array, 4 and 9 nanoholes array in a metallic film gold nanoparticle with different thickness (20,50,100) nm on SiO2 substrate with refractive index 1.46, we designed two different geometries; 4- holes: hole radius r1=200 nm, period p1=600 nm; and 9- holes: r2=100 nm, period p2=300 nm. Transmission and reflection spectrum have been calculated and simulated by FDTD Lumerical program. From results are observed the effect of thickness is interesting, transmission is increased at (t=20nm) for two arrays. Furthermore, the number of hole and its area has an influence on optical transmission and other parameters (E, H, Ref) which are characteristics of design of metallic nanostructure. We can see that there is a peak value of the wavelength at 519 nm approximately to 73% strong light transmission with 4-NHA in the other hand wavelength of 519 nm transmission is 45% with 9-NHA. strong light transmission is hopeful for many applications (biomedical devices, nanoantennas and laser optical fiber).
This document provides a review of recent research on exciting surface plasmon polaritons (SPPs) in the microwave and terahertz regimes using subwavelength patterns on metal surfaces. Key challenges in high-speed electronics like bandwidth, size, losses, and signal integrity can be addressed using spoof SPP structures. Such structures mimic the properties of natural SPPs and allow controlling the propagation of electromagnetic waves at lower frequencies. Various applications in chemical sensing, imaging, and communication have benefited from exciting SPPs in these frequency ranges. The document discusses the theoretical background and properties of SPPs and reviews research on different spoof SPP waveguide designs.
This senior design project report describes the design of a microstrip antenna to operate at multiple frequency bands for GSM, Wi-Fi, and GPS. The report includes an introduction to basic antenna theory and properties. It discusses the design objectives of achieving multi-band operation. Software simulations were used to design and optimize a rectangular patch geometry microstrip antenna. The antenna was then manufactured and test results were presented that showed operation at desired frequency bands. The project demonstrated the feasibility of integrating wireless applications using a single multiband microstrip antenna design.
MODELLING OF LAND MOBILE SATELLITE CHANNEL TO COUNTER CHANNEL OUTAGE ijdpsjournal
A Land mobile satellite service (LMSS) is an arm of mobile satellite system (MSS), in which a number of
services are its subset. To ensure network availability, high quality of service (QoS), and reduce outage on
the channel as a result of channel interferences during propagation, it is important to understand channel
behaviour in various transmission environments. Vast literature has been published on the subject of
channel models that attempted to improve on impairments in communication links: a large number has
focused on narrowband channels than wideband. Due to advances in recent technology wideband
modelling of satellite channels becomes necessary, which this research study is focused, particularly
model for Land Mobile Satellite (LMS) channel. This study models the complete behaviour of LMS
Channel based on the Lutz’s (1989) two-state statistical model but modified with two-state Markov chain
for two different transmission environments, namely: shadowing (line-of-sight) and un- shadowing (nonline-of-sight)
conditions. In order to reduce the effect of channel outages, satellite diversity approach was
employed in addition to the 2-state Markov chain. Simulations of these conditions were performed using
MATLAB programming language. The study concludes that satellite diversity reduces outage on the
channel, and when mobile terminals have access to two geostationary satellites simultaneously network
availability is assured compared to when it has only one satellite link.
Substrate Integrated Waveguide Based Leaky-Wave Antenna IRJET Journal
This document describes a novel leaky-wave antenna design based on a substrate integrated waveguide (SIW) with non-uniform slots. The key aspects are:
1) The antenna uses a SIW structure with slots of varying widths (non-uniform) to reduce side lobes and improve radiation efficiency compared to previous uniform slot designs.
2) Simulation results show the design has improved reflection coefficient (below -10 dB) and scans from broadside to near end-fire as frequency increases from 10.3 GHz to 12 GHz.
3) Radiation patterns at different frequencies within the band demonstrate the beam scanning ability of the design.
Modelling of Land Mobile Satellite Channel to Counter Channel Outage ijdpsjournal
A Land mobile satellite service (LMSS) is an arm of mobile satellite system (MSS), in which a number of
services are its subset. To ensure network availability, high quality of service (QoS), and reduce outage on
the channel as a result of channel interferences during propagation, it is important to understand channel
behaviour in various transmission environments. Vast literature has been published on the subject of
channel models that attempted to improve on impairments in communication links: a large number has
focused on narrowband channels than wideband. Due to advances in recent technology wideband
modelling of satellite channels becomes necessary, which this research study is focused, particularly
model for Land Mobile Satellite (LMS) channel. This study models the complete behaviour of LMS
Channel based on the Lutz’s (1989) two-state statistical model but modified with two-state Markov chain
for two different transmission environments, namely: shadowing (line-of-sight) and un- shadowing (nonline-of-sight)
conditions. In order to reduce the effect of channel outages, satellite diversity approach was
employed in addition to the 2-state Markov chain. Simulations of these conditions were performed using
MATLAB programming language. The study concludes that satellite diversity reduces outage on the
channel, and when mobile terminals have access to two geostationary satellites simultaneously network
availability is assured compared to when it has only one satellite link
1) Researchers experimentally generated and detected a radio beam with orbital angular momentum (OAM) and an electromagnetic vortex using a single antenna and spiral reflector.
2) Measurements of beam intensity and interference patterns between two receiving antennas matched numerical simulations and indicated the presence of a vortex and OAM in the radio beam.
3) The results demonstrate for the first time that OAM states can be imparted onto radio beams, opening applications in wireless communications, radar technology, and studies of plasma in astrophysical systems.
A PROXIMITY FEED DUAL BAND CIRCULAR SHAPED ANTENNA WITH SEMICIRCULAR GROUND P...Amitesh Raikwar
In this work, we present a Circular Shaped proximity feed
Microstrip Patch Antenna. The antenna is comprised of circular
shaped radiation patch and this radiating patch is faded
by proximity coupling. The ground plane of the antenna has
Semicircular pattern to improve the coupling level of the
patch. The simulated result shows it provides the return loss
less than -10 dB for two frequencies 1.27 GHz and 1.43 GHz
which could be a useful frequencies for wireless communication
system. The simulation work is carried out on IE3D
software, a product of Zeland Software Company.
Analysis of airborne dust effects on terrestrialmicrowave propagation in arid...journalBEEI
Sand and dust storms are environmental phenomena ,during these storms optical visibility might be decreased, consequently, atmospheric attenuation is clearly noticed.Micro-wave (MW) and Milimeter-wave (mm) propagation is severely affected by dust and sand storms in considerable areas around the world. Suspended dust particles may directly cause attenuation and cross polarization to the Electromagnetic waves propagating through the storm. In this paper, a thorough investigation of dust storm characteristics based onmeasured optical visibility and relative humidity is presented. In addition,the dust storms effects of on Micro-wave and Millimeter-wave propagation have been studied based on data measured Received Signal levels (RSL)and dust storm characteristics synchronously. Analyticaldustattenuationmodels predictions are matched to the measured attenuationdata at 14 GHz and 21 GHz. It has been found that the measured attenuation is approximately ten times higher than the predicted attenuation for both frequencies.
Review of Space-charge Measurement using Pulsed Electro- Acoustic Method: Adv...IJERA Editor
The pulsed electro acoustic (PEA) technique is the most widely used method to measure space charge
distributions in insulating materials. The PEA technique has undergone some advancement since the over
twenty years it was first implemented such as in its spatial resolution and sensitivity. In this article a review of
the technique was carried out and its advantages, limitations, progress and prospects were discussed.
A Master of ScienceProject Report Optical cmms-oaa516Olufisayo Adekile
This document is a project report submitted by a student for their Master of Science degree. It investigates advanced methods of multiplexing for future terabit optical communications by comparing and analyzing the tolerance of optical orthogonal frequency-division multiplexing (OFDM) to effects such as dispersion and nonlinearity. The report includes an abstract, table of contents, introduction providing background on optical communications and specifying the project aim and objectives, and chapters on historical background, advanced multiplexing methods with a focus on OFDM, simulating an optical OFDM system using MATLAB, and concluding remarks.
Dielectric resonator antenna excited using t strip feed line for wideband app...Conference Papers
The document presents a dielectric resonator antenna (DRA) excited using a T-strip feed line for wideband applications. The proposed antenna structure achieves an impedance bandwidth of 1.5 GHz covering 27.5-29 GHz with a peak gain of 6.6 dBi and high radiation efficiency of 89%. Simulation results show that the T-strip feed line improves the bandwidth of the DRA compared to other feeding methods. The proposed antenna is suitable for wideband communication applications such as 5G.
The Effects of Interferenceon the Transmission and Coverage in High Buildings IJERA Editor
Wireless communication is one of the most rapidly developing technologies in recent time, with wonderful
services and products emerging together. These developments present huge challenges for communication
engineers, as the demand for increased wireless capacity grow fast. Re-using the limited available spectrum will
results a critical issue that affects the system performance, which is co-channel interference. This issue will
limits the uplink coverage and capacity of the wireless system. It is needed to come up with such method of
interference cancellation. We will investigate the transmission in multiple floors building by deploying
femtocell based distributed antenna that connected at each entire floor, the signal will be processed by jointing
all femto base stations for all cells in the building. We will try to introduce a solution to the arising problem of
co-channel interference from frequency reuse, by measuring and analyzing the gain when deploying interference
cancellation at each base station.
Broadband high photoresponse from pure monolayer graphene photodetectorCarlos Bella
This document summarizes a research article that reports on the development of a high-performance photodetector using pure monolayer graphene. The researchers introduced electron trapping centers and created a bandgap in graphene through band structure engineering. This allowed them to achieve a high photoresponsivity of 8.61 A/W, about three orders of magnitude higher than previous graphene photodetectors. Additionally, they demonstrated broadband photoresponse from visible to mid-infrared wavelengths, the broadest reported for a pure graphene photodetector. By introducing defects and quantum confinement effects, they were able to greatly increase the lifetime of photo-generated carriers and achieve carrier multiplication, resulting in high photoresponsivity across a wide spectrum
q This document describes a visualization tool developed by researchers at the University of Bristol to simulate 5G radio interface concepts using geographical data and electromagnetic wave modeling.
q The tool provides dynamic representations of channel performance metrics and integrates beam tracking responses to aid understanding of 5G millimeter wave technologies. It also displays a "Green Link Budget" metric for evaluating power efficient radio link selection.
q The researchers integrated an algorithm for beam tracking within the visualization tool by selecting the strongest beam among options. Snapshots from the tool demonstrate beam tracking between two base stations.
Challenging Issues in Inter-Satellite Optical Wireless Systems (IsOWC) and it...idescitation
Inter-satellite optical wireless communication
system (IsOWC), one of the important applications of FSO
(Free Space Optics) technology, will be deployed in space in
the near future because of providing power efficient and high
bandwidth allocation facilities unlike present microwave
satellite systems. In this paper, we have deliberated a
presentation of different challenging issues in achieving a
prolonged inter satellite link for an IsOWC system under
different situations and conditions. This work is also
emphasized on the suggested techniques to combat with the
degrading factors to put into practice of high speed IsOWC
system with minimum BER.
Magnetic resonance coupling for 5G WPT applicationsjournalBEEI
Inductive Wireless Power Transfer (IWPT) is the most popular and common technology for the resonance coupling power transfer. However, in 2007 it has experimentally demonstrated by a research group from Massachusets Institute of Technology (MIT) that WPT can be improved by using Magnetic Resonance Coupling Wireless Power Transfer (MRC WPT) in terms of the coupling distance and efficiency. Furthermore, by exploiting the unused, high-frequency mm-wave band which are ranging from 3~300 GHz frequency band, the next 5G generations of wireless networks will be able to support a higher number of devices with the increasing data rate, higher energy efficiency and also compatible with the previous technology. In this work, a square planar inductor with the dimension of 6.1 x 6.1 mm is designed, and the resonators have the same self-resonance frequency at 14 GHz. The coil resonators have been laid on Silicon and Oxide substrate to reduce the loss in the design. From the CST software simulation and the analytical model in MATLAB software, it has been shown that the MRC WPT design has improved the performance of IWPT design by 40% power transfer efficiency. MRC WPT design also has larger H-Field value which is 705.5 A/m, as compared to the IWPT design which has only 285.6 A/m when both Transmitter(Tx) and Reciever(RX) is at 0.3 mm coupling distance.
A wideband hybrid plasmonic fractal patch nanoantennIAEME Publication
This document proposes a wideband plasmonic optical fractal patch nanoantenna for use in intra-chip and inter-chip optical communications. The antenna is based on a hybrid plasmonic structure consisting of silver, silicon dioxide, and silicon. It operates over multiple optical bands from 1460-1625nm. The antenna design is iteratively modified using a rectangular tree-shaped fractal approach to increase its bandwidth. Simulation results show the second iteration design has an impedance bandwidth of around 38.5 THz, around 4 times greater than the initial design. The fractal antenna provides a gain up to 7.5dB and radiation efficiency of around 97% across the operating bandwidth.
The document describes a complementary split ring resonator (CSRR) based metamaterial designed for C-band microwave applications. The CSRR unit cell has a double negative refractive index region from 6.34-7.39 GHz and 8.2-9.98 GHz. It was fabricated on an FR4 substrate with dimensions of 5.5x5.5 mm2. Both simulation and measurement results showed effective negative permeability and permittivity within the C-band frequency range, demonstrating its potential for microwave applications.
Cost effective approach for 100 gbps vcsel-mmf lan’seSAT Journals
This document analyzes the performance of 100 Gbps MIMO systems over multimode fiber using VCSEL lasers and different modulation formats. It is found that MDRZ modulation provides the best performance with a reach of 28 km. Analysis shows that VCSEL laser performance degrades with increasing temperature, bias current, and cavity volume. MDRZ modulation outperforms NRZ and CSRZ, enabling longer transmission distances. A 100 Gbps 10x10 MIMO system using MDRZ is tested over lengths from 8-28 km, showing decreasing quality with increasing distance.
Microwave photonics is the study of high-speed photonic devices operating at microwave or millimeter wave frequencies and their use in microwave or photonic systems. This paper provides an overview of this multidisciplinary field, including typical investigations such as signal generation, processing, and transmission via optical links. It discusses key components such as traveling wave electroabsorption modulators and detectors, and how microwave technologies can improve photonic bandwidth. Broad applications are presented, including photonic signal generation, EMC sensing, testing, hybrid fiber-coax systems, fiber-radio, and antenna remoting.
Compensation of dielectric cover effects on cp hexagonal microstrip antennaIAEME Publication
This document summarizes a research article that examines the effects of a dielectric cover layer on the performance of a circularly polarized hexagonal microstrip antenna. It first describes how circular polarization is achieved in patch antennas and discusses previous work on perturbations used to generate circular polarization. It then explains how additional dielectric layers can negatively impact antenna characteristics like resonant frequency and efficiency. The document proposes using an air gap between the dielectric layer and ground plane to compensate for these effects. It provides design specifications for the hexagonal antenna and shows simulated and fabricated antenna models. The research aims to maintain antenna performance while adding a protective dielectric cover layer.
This document provides a summary of an individual's qualifications including education, research experience, areas of expertise, professional experience, and teaching experience. Some key details:
- The individual holds a Ph.D. in Electrical Engineering from the University of New Brunswick and has over 30 years of experience in academia and industry.
- Research areas of expertise include antennas, metamaterials, electromagnetic waves, microwave engineering, GPS, wireless communications systems.
- Professional experience includes senior research engineer roles and over 20 years as a professor, where the individual has supervised several graduate students to completion of Ph.D./M.Sc. degrees.
- Teaching experience covers both undergraduate and graduate courses in relevant fields at several
Dielectric Resonator Reflectarray Antenna Unit Cells for 5G Applications IJECEIAES
This paper presents an investigation for the performance comparison of three different unit cell configurations operating at 26 GHz for 5G applications. The unit cells are cross shape dielectric resonator, cross microstrip patch and cross hybrid dielectric resonator. Verification of the comparison has been done by simulations using commercial Computer Simulation Technology Microwave Studio (CST MWS). The simulated results for reflection phase, slope variation, reflection loss and 10% bandwidth were analyzed and compared. The results indicate that the optimum configuration to be deployed for the reflectarray’s unit element in order to fulfill the 5G requirements of a wide bandwidth is the cross hybrid DRA. This configuration is a combination of cross DRA with cross microstrip patch as the parasitic element in order to tune the phase and provide a wide phase range with smooth variation slope. Cross hybrid DRA provided a wide phase range of 520° with 0.77 dB loss and 10% bandwidth of 160 MHz.
The document discusses satellite communication links, including:
- Design of satellite links, which follow free-space propagation and are affected by factors like rain attenuation.
- Link budgets and their interpretation, which use decibel calculations to account for gains and losses across transmitting, receiving, and atmospheric elements.
- Multiple access systems and frequency band trade-offs that satellite communication must consider.
The document discusses satellite communication links, including:
1) The design of satellite links, which involves line-of-sight transmission between earth stations and satellites governed by free-space propagation and atmospheric effects.
2) Link budgets and their interpretation, which quantify gains and losses across transmitter, receiver, and propagation to determine overall carrier-to-noise ratio and performance.
3) Multiple access systems and frequency band trade-offs used for satellite communication.
A hybrid algorithm for wave-front corrections applied to satellite-to-ground ...TELKOMNIKA JOURNAL
Laser communications hold accurate data rate for ground satellite links. The laser beam is transmitted through the atmosphere. The clear-air turbulence induces a number of phase distortions that damage wave-front. Adaptive optics (AO) treats wave front correction. The nature of AO systems is iterative; it can be integrated in metaheuristic algorithms such as genetic algorithm (GA). This paper presents improved version of algorithm for wave-front corrections. The improved algorithm is based on genetic algorithm (GA) and adaptive optics approach (OA). It is implemented in a computer simulation model called object-oriented matlab adaptive optics (OOMAO). The optimisation process involves best possible GA parameters as a function of population size, iteration count, and the actuators’ voltage intervals. Results show that the application of GA improves the performance of AO in wave-front corrections and the communication between satellite-to-ground laser links as well.
Modelling of Land Mobile Satellite Channel to Counter Channel Outage ijdpsjournal
A Land mobile satellite service (LMSS) is an arm of mobile satellite system (MSS), in which a number of
services are its subset. To ensure network availability, high quality of service (QoS), and reduce outage on
the channel as a result of channel interferences during propagation, it is important to understand channel
behaviour in various transmission environments. Vast literature has been published on the subject of
channel models that attempted to improve on impairments in communication links: a large number has
focused on narrowband channels than wideband. Due to advances in recent technology wideband
modelling of satellite channels becomes necessary, which this research study is focused, particularly
model for Land Mobile Satellite (LMS) channel. This study models the complete behaviour of LMS
Channel based on the Lutz’s (1989) two-state statistical model but modified with two-state Markov chain
for two different transmission environments, namely: shadowing (line-of-sight) and un- shadowing (nonline-of-sight)
conditions. In order to reduce the effect of channel outages, satellite diversity approach was
employed in addition to the 2-state Markov chain. Simulations of these conditions were performed using
MATLAB programming language. The study concludes that satellite diversity reduces outage on the
channel, and when mobile terminals have access to two geostationary satellites simultaneously network
availability is assured compared to when it has only one satellite link
1) Researchers experimentally generated and detected a radio beam with orbital angular momentum (OAM) and an electromagnetic vortex using a single antenna and spiral reflector.
2) Measurements of beam intensity and interference patterns between two receiving antennas matched numerical simulations and indicated the presence of a vortex and OAM in the radio beam.
3) The results demonstrate for the first time that OAM states can be imparted onto radio beams, opening applications in wireless communications, radar technology, and studies of plasma in astrophysical systems.
A PROXIMITY FEED DUAL BAND CIRCULAR SHAPED ANTENNA WITH SEMICIRCULAR GROUND P...Amitesh Raikwar
In this work, we present a Circular Shaped proximity feed
Microstrip Patch Antenna. The antenna is comprised of circular
shaped radiation patch and this radiating patch is faded
by proximity coupling. The ground plane of the antenna has
Semicircular pattern to improve the coupling level of the
patch. The simulated result shows it provides the return loss
less than -10 dB for two frequencies 1.27 GHz and 1.43 GHz
which could be a useful frequencies for wireless communication
system. The simulation work is carried out on IE3D
software, a product of Zeland Software Company.
Analysis of airborne dust effects on terrestrialmicrowave propagation in arid...journalBEEI
Sand and dust storms are environmental phenomena ,during these storms optical visibility might be decreased, consequently, atmospheric attenuation is clearly noticed.Micro-wave (MW) and Milimeter-wave (mm) propagation is severely affected by dust and sand storms in considerable areas around the world. Suspended dust particles may directly cause attenuation and cross polarization to the Electromagnetic waves propagating through the storm. In this paper, a thorough investigation of dust storm characteristics based onmeasured optical visibility and relative humidity is presented. In addition,the dust storms effects of on Micro-wave and Millimeter-wave propagation have been studied based on data measured Received Signal levels (RSL)and dust storm characteristics synchronously. Analyticaldustattenuationmodels predictions are matched to the measured attenuationdata at 14 GHz and 21 GHz. It has been found that the measured attenuation is approximately ten times higher than the predicted attenuation for both frequencies.
Review of Space-charge Measurement using Pulsed Electro- Acoustic Method: Adv...IJERA Editor
The pulsed electro acoustic (PEA) technique is the most widely used method to measure space charge
distributions in insulating materials. The PEA technique has undergone some advancement since the over
twenty years it was first implemented such as in its spatial resolution and sensitivity. In this article a review of
the technique was carried out and its advantages, limitations, progress and prospects were discussed.
A Master of ScienceProject Report Optical cmms-oaa516Olufisayo Adekile
This document is a project report submitted by a student for their Master of Science degree. It investigates advanced methods of multiplexing for future terabit optical communications by comparing and analyzing the tolerance of optical orthogonal frequency-division multiplexing (OFDM) to effects such as dispersion and nonlinearity. The report includes an abstract, table of contents, introduction providing background on optical communications and specifying the project aim and objectives, and chapters on historical background, advanced multiplexing methods with a focus on OFDM, simulating an optical OFDM system using MATLAB, and concluding remarks.
Dielectric resonator antenna excited using t strip feed line for wideband app...Conference Papers
The document presents a dielectric resonator antenna (DRA) excited using a T-strip feed line for wideband applications. The proposed antenna structure achieves an impedance bandwidth of 1.5 GHz covering 27.5-29 GHz with a peak gain of 6.6 dBi and high radiation efficiency of 89%. Simulation results show that the T-strip feed line improves the bandwidth of the DRA compared to other feeding methods. The proposed antenna is suitable for wideband communication applications such as 5G.
The Effects of Interferenceon the Transmission and Coverage in High Buildings IJERA Editor
Wireless communication is one of the most rapidly developing technologies in recent time, with wonderful
services and products emerging together. These developments present huge challenges for communication
engineers, as the demand for increased wireless capacity grow fast. Re-using the limited available spectrum will
results a critical issue that affects the system performance, which is co-channel interference. This issue will
limits the uplink coverage and capacity of the wireless system. It is needed to come up with such method of
interference cancellation. We will investigate the transmission in multiple floors building by deploying
femtocell based distributed antenna that connected at each entire floor, the signal will be processed by jointing
all femto base stations for all cells in the building. We will try to introduce a solution to the arising problem of
co-channel interference from frequency reuse, by measuring and analyzing the gain when deploying interference
cancellation at each base station.
Broadband high photoresponse from pure monolayer graphene photodetectorCarlos Bella
This document summarizes a research article that reports on the development of a high-performance photodetector using pure monolayer graphene. The researchers introduced electron trapping centers and created a bandgap in graphene through band structure engineering. This allowed them to achieve a high photoresponsivity of 8.61 A/W, about three orders of magnitude higher than previous graphene photodetectors. Additionally, they demonstrated broadband photoresponse from visible to mid-infrared wavelengths, the broadest reported for a pure graphene photodetector. By introducing defects and quantum confinement effects, they were able to greatly increase the lifetime of photo-generated carriers and achieve carrier multiplication, resulting in high photoresponsivity across a wide spectrum
q This document describes a visualization tool developed by researchers at the University of Bristol to simulate 5G radio interface concepts using geographical data and electromagnetic wave modeling.
q The tool provides dynamic representations of channel performance metrics and integrates beam tracking responses to aid understanding of 5G millimeter wave technologies. It also displays a "Green Link Budget" metric for evaluating power efficient radio link selection.
q The researchers integrated an algorithm for beam tracking within the visualization tool by selecting the strongest beam among options. Snapshots from the tool demonstrate beam tracking between two base stations.
Challenging Issues in Inter-Satellite Optical Wireless Systems (IsOWC) and it...idescitation
Inter-satellite optical wireless communication
system (IsOWC), one of the important applications of FSO
(Free Space Optics) technology, will be deployed in space in
the near future because of providing power efficient and high
bandwidth allocation facilities unlike present microwave
satellite systems. In this paper, we have deliberated a
presentation of different challenging issues in achieving a
prolonged inter satellite link for an IsOWC system under
different situations and conditions. This work is also
emphasized on the suggested techniques to combat with the
degrading factors to put into practice of high speed IsOWC
system with minimum BER.
Magnetic resonance coupling for 5G WPT applicationsjournalBEEI
Inductive Wireless Power Transfer (IWPT) is the most popular and common technology for the resonance coupling power transfer. However, in 2007 it has experimentally demonstrated by a research group from Massachusets Institute of Technology (MIT) that WPT can be improved by using Magnetic Resonance Coupling Wireless Power Transfer (MRC WPT) in terms of the coupling distance and efficiency. Furthermore, by exploiting the unused, high-frequency mm-wave band which are ranging from 3~300 GHz frequency band, the next 5G generations of wireless networks will be able to support a higher number of devices with the increasing data rate, higher energy efficiency and also compatible with the previous technology. In this work, a square planar inductor with the dimension of 6.1 x 6.1 mm is designed, and the resonators have the same self-resonance frequency at 14 GHz. The coil resonators have been laid on Silicon and Oxide substrate to reduce the loss in the design. From the CST software simulation and the analytical model in MATLAB software, it has been shown that the MRC WPT design has improved the performance of IWPT design by 40% power transfer efficiency. MRC WPT design also has larger H-Field value which is 705.5 A/m, as compared to the IWPT design which has only 285.6 A/m when both Transmitter(Tx) and Reciever(RX) is at 0.3 mm coupling distance.
A wideband hybrid plasmonic fractal patch nanoantennIAEME Publication
This document proposes a wideband plasmonic optical fractal patch nanoantenna for use in intra-chip and inter-chip optical communications. The antenna is based on a hybrid plasmonic structure consisting of silver, silicon dioxide, and silicon. It operates over multiple optical bands from 1460-1625nm. The antenna design is iteratively modified using a rectangular tree-shaped fractal approach to increase its bandwidth. Simulation results show the second iteration design has an impedance bandwidth of around 38.5 THz, around 4 times greater than the initial design. The fractal antenna provides a gain up to 7.5dB and radiation efficiency of around 97% across the operating bandwidth.
The document describes a complementary split ring resonator (CSRR) based metamaterial designed for C-band microwave applications. The CSRR unit cell has a double negative refractive index region from 6.34-7.39 GHz and 8.2-9.98 GHz. It was fabricated on an FR4 substrate with dimensions of 5.5x5.5 mm2. Both simulation and measurement results showed effective negative permeability and permittivity within the C-band frequency range, demonstrating its potential for microwave applications.
Cost effective approach for 100 gbps vcsel-mmf lan’seSAT Journals
This document analyzes the performance of 100 Gbps MIMO systems over multimode fiber using VCSEL lasers and different modulation formats. It is found that MDRZ modulation provides the best performance with a reach of 28 km. Analysis shows that VCSEL laser performance degrades with increasing temperature, bias current, and cavity volume. MDRZ modulation outperforms NRZ and CSRZ, enabling longer transmission distances. A 100 Gbps 10x10 MIMO system using MDRZ is tested over lengths from 8-28 km, showing decreasing quality with increasing distance.
Microwave photonics is the study of high-speed photonic devices operating at microwave or millimeter wave frequencies and their use in microwave or photonic systems. This paper provides an overview of this multidisciplinary field, including typical investigations such as signal generation, processing, and transmission via optical links. It discusses key components such as traveling wave electroabsorption modulators and detectors, and how microwave technologies can improve photonic bandwidth. Broad applications are presented, including photonic signal generation, EMC sensing, testing, hybrid fiber-coax systems, fiber-radio, and antenna remoting.
Compensation of dielectric cover effects on cp hexagonal microstrip antennaIAEME Publication
This document summarizes a research article that examines the effects of a dielectric cover layer on the performance of a circularly polarized hexagonal microstrip antenna. It first describes how circular polarization is achieved in patch antennas and discusses previous work on perturbations used to generate circular polarization. It then explains how additional dielectric layers can negatively impact antenna characteristics like resonant frequency and efficiency. The document proposes using an air gap between the dielectric layer and ground plane to compensate for these effects. It provides design specifications for the hexagonal antenna and shows simulated and fabricated antenna models. The research aims to maintain antenna performance while adding a protective dielectric cover layer.
This document provides a summary of an individual's qualifications including education, research experience, areas of expertise, professional experience, and teaching experience. Some key details:
- The individual holds a Ph.D. in Electrical Engineering from the University of New Brunswick and has over 30 years of experience in academia and industry.
- Research areas of expertise include antennas, metamaterials, electromagnetic waves, microwave engineering, GPS, wireless communications systems.
- Professional experience includes senior research engineer roles and over 20 years as a professor, where the individual has supervised several graduate students to completion of Ph.D./M.Sc. degrees.
- Teaching experience covers both undergraduate and graduate courses in relevant fields at several
Dielectric Resonator Reflectarray Antenna Unit Cells for 5G Applications IJECEIAES
This paper presents an investigation for the performance comparison of three different unit cell configurations operating at 26 GHz for 5G applications. The unit cells are cross shape dielectric resonator, cross microstrip patch and cross hybrid dielectric resonator. Verification of the comparison has been done by simulations using commercial Computer Simulation Technology Microwave Studio (CST MWS). The simulated results for reflection phase, slope variation, reflection loss and 10% bandwidth were analyzed and compared. The results indicate that the optimum configuration to be deployed for the reflectarray’s unit element in order to fulfill the 5G requirements of a wide bandwidth is the cross hybrid DRA. This configuration is a combination of cross DRA with cross microstrip patch as the parasitic element in order to tune the phase and provide a wide phase range with smooth variation slope. Cross hybrid DRA provided a wide phase range of 520° with 0.77 dB loss and 10% bandwidth of 160 MHz.
The document discusses satellite communication links, including:
- Design of satellite links, which follow free-space propagation and are affected by factors like rain attenuation.
- Link budgets and their interpretation, which use decibel calculations to account for gains and losses across transmitting, receiving, and atmospheric elements.
- Multiple access systems and frequency band trade-offs that satellite communication must consider.
The document discusses satellite communication links, including:
1) The design of satellite links, which involves line-of-sight transmission between earth stations and satellites governed by free-space propagation and atmospheric effects.
2) Link budgets and their interpretation, which quantify gains and losses across transmitter, receiver, and propagation to determine overall carrier-to-noise ratio and performance.
3) Multiple access systems and frequency band trade-offs used for satellite communication.
A hybrid algorithm for wave-front corrections applied to satellite-to-ground ...TELKOMNIKA JOURNAL
Laser communications hold accurate data rate for ground satellite links. The laser beam is transmitted through the atmosphere. The clear-air turbulence induces a number of phase distortions that damage wave-front. Adaptive optics (AO) treats wave front correction. The nature of AO systems is iterative; it can be integrated in metaheuristic algorithms such as genetic algorithm (GA). This paper presents improved version of algorithm for wave-front corrections. The improved algorithm is based on genetic algorithm (GA) and adaptive optics approach (OA). It is implemented in a computer simulation model called object-oriented matlab adaptive optics (OOMAO). The optimisation process involves best possible GA parameters as a function of population size, iteration count, and the actuators’ voltage intervals. Results show that the application of GA improves the performance of AO in wave-front corrections and the communication between satellite-to-ground laser links as well.
Unconsidered but influencing interference in unmanned aerial vehicle cabling ...IJECEIAES
The increasing complexity of electrical and electronic systems in unmanned aerial vehicles (UAVs) has raised concerns regarding unwanted electromagnetic interference (EMI) due to limited compartment space. Recent studies have highlighted the UAV cabling as the primary pathway for interference. This paper presents a novel approach to investigating the effects of interference power, polarization angle, and distance from the interference source on EMI in UAV cable systems. Measurements and simulations were performed to analyze the influence of these factors on the radiation received by the cable. A linear dipole antenna, operating at a frequency of 905 MHz, served as the radiation source, while a single wire cable pair terminated with a 50-ohm resistor was employed as the victim. The findings reveal that the power transmitted by the source, the distance between the cable and the source, and the polarization angle have a significant impact on the electromagnetic interference received by the cable. Notably, a perpendicular orientation of the cable to the interference source (antenna) in the far-field yielded a reduction of up to 15 dBm in EMI. The results underscore the necessity for more sophisticated models and comprehensive measurements to fully comprehend the diverse factors affecting polarization losses in practical scenarios.
Scattering Regimes for Underwater Optical Wireless Communications using Monte...IJECEIAES
Optical wireless communications has shown tremendous potential for underwater applications as it can provide higher bandwidth and better security compared to acoustic technologies. In this paper, an investigation on scattering regimes for underwater links using Monte Carlo simulation has been presented.While the focus of this paper is on diffuse links, the simulation results of collimated links is also provided for comparison purpose. Three types of water namely clear, coastal and turbid water are being used in the simulation. It is shown that the effect of scattering on the path loss cannot be accurately modeled by the existing channel model; ie. Beers-Lambert (BL) law. It has been shown that the distance at which the unscattered light drops to zero can be used to estimate the transition point for the scattering regimes in case of diffuse links. The transition point for diffuse links in coastal water and turbid water can be estimated to be around 22 m and 4 m respectively. Further analysis on the scattering order probability at different scattering regimes illustrates how scattering is affected by beam size, water turbidity and distance. From the frequency response plot, it is estimated that the bandwidth of several order of GHz can be achieved when the links are operating in the minimal scattering region and will reduce to several hundreds of MHz when the link is operating in multiple scattering region.
Average symbol error rate analysis of reconfigurable intelligent surfaces-as...IJECEIAES
Optical wireless communication (OWC) has attracted significant interest recently in academia and industry. Free-space optical (FSO) communication systems are where free space acts as a communication channel between transceivers that are line of sight (LOS) for the successful transmission of optical signals. The FSO transmissions through the atmosphere, nevertheless, bring significant challenges, besides the uncertainty of atmospheric channels, especially the signal fading due to the atmospheric turbulence, attenuation and pointing errors caused by the random beam misalignments between transceivers, signal obstruction due to buildings or trees can pre-vent the transmitted message to reach the destination. This study theoretically investigates the average symbol error rate (ASER) of reconfigurable intelligent surfaces (RIS) assisted FSO link over log-normal turbulence channels. The RIS effect is examined by considering the influence of link distance, transmitted optical power, and quadrature amplitude modulation (QAM) scheme on the ASER.
The document discusses key parameters that influence the design of satellite communication links, including:
1. Choice of operating frequency which is governed by factors like propagation considerations and interference issues. Higher frequencies offer more bandwidth but more rain attenuation.
2. Noise considerations and how the quality of received signals depends on carrier-to-noise ratio across the uplink, satellite, and downlink.
3. Interference problems from terrestrial microwave links using the same frequencies or between satellites and earth stations using the same frequencies.
4. Propagation effects like free-space loss, rain attenuation that increases with frequency and lower elevation angles, and cloud attenuation at higher Ka/V bands.
This document discusses channel modeling for 5G NR non-terrestrial networks (NTN). It covers the system model, which includes topology, large-scale pathloss modeling, and antenna patterns. For topology, it describes using Earth-centered Earth-fixed coordinates and UV mapping to represent satellite positions and layout beams and user equipment. It then discusses components of the pathloss model for NTN including free space pathloss, clutter loss, shadow fading, and atmospheric, ionospheric, and tropospheric attenuations. The document concludes with describing the use of directional reflector antennas and providing example antenna patterns for geostationary and low Earth orbit satellite configurations.
1. The document describes a microstrip diplexer design inspired by electromagnetically induced transparency (EIT). EIT allows wave propagation within a medium's absorption spectrum through quantum interference between atomic transition pathways.
2. The proposed diplexer exploits an analogous EIT-like interference mechanism using pairs of unequal open-circuit stubs on a microstrip transmission line. This creates separate transparent passbands for diplexing action at different frequencies.
3. A prototype was fabricated at C-band frequencies with passbands centered at 4.6 GHz and 5.5 GHz, achieving insertion losses of 0.59 dB and 0.61 dB respectively. High isolation of 40 dB was observed between the passbands due
Time Domain Modelling of Optical Add-drop filter based on Microcavity Ring Re...iosrjce
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document summarizes the time domain modeling of an optical add-drop filter based on microcavity ring resonators. It uses the Multiresolution Time Domain (MRTD) technique to analyze the transmission characteristics of single and double ring configurations. The MRTD method provides high numerical accuracy while reducing computational burden compared to FDTD. The analysis investigates parameters like gap size, distance between rings, and ring/waveguide width to understand their effects on transmitted power and quality factors. Studies of a 3.4 μm diameter ring show quality factors of several thousand and a free spectral range of 9 THz can be achieved in the 1.55 μm wavelength range.
Design and manufacturing of iris waveguide filters for satellite communicationTELKOMNIKA JOURNAL
We propose in this paper, two bandpass filters in waveguide technology having rectangular symmetrical discontinuities with a half-radius r, designed and operating respectively in the X-Band (9-11.5) GHz and C-Band (3.5-5.5) GHz. These filters consists of eight irises placed symmetrically respectively on standard rectangular waveguides WR90 and WR229 in which resonant irises are inserted. These irises are used to couple the sections very strongly in this filter, which allows the bandwidth to be increased and the matching to be controlled. The comparison between the numerical and electromagnetic results, which we obtained for the filters, constitutes a means of validation of computer simulation technology (CST) environment and Mician for the design of the other circuit elements in the various frequency bands. We observed excellent consistency between the simulation curves and those of the measurements. The results obtained are promising and pave the way for the use of these structures in the fields of telecommunications.
The calculation of the field of an antenna located near the human headjournalBEEI
In this work, a numerical calculation was carried out in one of the universal programs for automatic electro-dynamic design. The calculation is aimed at obtaining numerical values for specific absorbed power (SAR). It is the SAR value that can be used to determine the effect of the antenna of a wireless device on biological objects; the dipole parameters will be selected for GSM1800. Investigation of the influence of distance to a cell phone on radiation shows that absorbed in the head of a person the effect of electromagnetic radiation on the brain decreases by three times this is a very important result the SAR value has decreased by almost three times it is acceptable results.
Design and software implementation of radio frequency satellite link based on...TELKOMNIKA JOURNAL
The satellite communication providea utilization of radio frequency links. Specific frequencies are dedicated for satellite correspondences through global administrative and coordination procedures which keeps impedance amongframeworks. Over typical work, the satellite receives uplinked indicator fromearth. Progressions its frequency marginally will keep away from self-intervention then re-transmits signal ahead the downlink on the land. Pathloss depicts characteristic Propagate outside the sending signal front as it goes bythe space. A software defined radio (SDR) is a flexible technology that aimsto replace all hardware by software to enables the design of adaptive communications systems such as changing frequencies, modulation schemes and data rates. Applied to small satellites, some of the implications areincreased data through put when down-linking or up-linking by varying communications parameters and making use of one hardware design and implementation for communicating for many missions, just by updating the software. Therefore, development time for small satellite communication systems can be reduced in the future. This paper analyzes, design and software implementation of radio frequency satellite communications links under noisy channels such as phase/frequency offsets and noise temperature. Modulation schemes such as 64QAM system is used based on Matlab tools to implement the results. Obtained results shows a good response that get the goal from the paper.
This document summarizes research on modeling the effects of adding a rectangular slot to a microstrip patch antenna. The researchers developed an analytical model to predict how the resonant frequency changes based on the slot's length, width, and position. They conducted simulations varying the slot parameters and found that the resonant frequency generally follows a harmonic behavior similar to an antenna without a slot. Experimental antenna prototypes were fabricated and tested, finding good agreement with simulation results. Mathematical functions are presented that can describe how the slot affects specific antenna characteristics.
Fog attenuation penalty analysis in terrestrial optical wireless communicatio...nooriasukmaningtyas
In metropolitan communication infrastructures a revolutionary technique is emerge known as terrestrial optical wireless communication (OWC), which makes a high-rise building connection is possible. Even with this solution, there are many other problems like the influence of haze and fog in the propagation channel which obstruct and scatter OWC propagation light and consequently led to a big attenuation, due to propagate in temporal, angular and spatial of the light signal. Not to mention the minimum visibility that discourages the implementation of the pointing errors (PE) and tracking system. This present work aims to analyze the interrelation between multiple scattering (dense fog, heavy fog, light fog, heavy haze and light haze) and receiver PE under modified duo-binary return-to-zero (MDRZ) system. We found that PE caused by beam swag is the main controlling factor and industriously minimize the link margin, signal-to-noise ratio (SNR), and raise the bit error rate (BER) when there is an increasing the turbulence strength and the track length. We recommended to guarantee transmitter– receiver alignment by installing a variable field of view (FOV) receiver (a tracking system) to overcome the scattering impact of the fog that make render urban laser communication effective in the presence of PE.
This document discusses the performance analysis of a microstrip printed antenna conformed on a cylindrical body operating at a resonance frequency of 4.6 GHz for the TM01 mode. It begins with an introduction to microstrip antennas and the effects of curvature. It then presents mathematical models for the electric and magnetic fields, input impedance, return loss, and voltage standing wave ratio for a curved microstrip antenna. Results show the resonance frequency shifts 35 MHz as the radius of curvature changes from 6 mm to a flat antenna. Graphs also show the real and imaginary parts of input impedance vary with frequency for different radii of curvature.
A new hybrid method for mutual coupling minimization of an antenna array IJECEIAES
In this paper, a simultaneous application of geometric modification on patch elements and electromagnetic band gap (EBG) electromagnetic bandgap structures (hybrid method) has been suggested for 3.5 GHz wireless communication applications, to minimize the mutual coupling between radiating elements of microstrip array antennas. The suggested EBG slotted structure is composed of a one square ring and three squares placed on Rogers RO3010 having 10.2 and h=1.27 mm which presents respectively its dielectric constant and thickness. In this approach, the patch elements are geometrically modified, while also employing EBG structures, formed by four EBG cells, placed between the array elements at a near distance. The modification of the geometry of the antenna and the introduction of EBG reduces the mutual coupling of an array antenna with approximately 33 dB on the one hand and improves the antenna gain by approximately 0.43 dB on the other hand. Initially, slots are introduced in the patch geometry and then four EBG unit cells are inserted between two patches, operating at 3.5 GHz. The antenna array design parameters were optimized.
An analytical method with numerical results to be used in the design of optic...nooriasukmaningtyas
This study develops an analytical method with numerical results for the design of optical slab waveguides for optical communication system applications. An optical slab waveguide structure made of silicon on silicon dioxide material is designed and analyzed. The effective index of the mode is studied against variations in the waveguide dimensions. Transmission and reflection coefficients are studied and compared to the wavelength and dimensions of the waveguide. Variations are sketched with the x-axis, in addition to the electric field intensity distribution and effective refractive index. Waveguide bending loss is also studied with waveguide thickness and length variations within three waveguide transmission windows of 850 nm, 1300nm, and 1550nm.
Adaptive 3D ray tracing approach for indoor radio signal prediction at 3.5 GHzIJECEIAES
This paper explained an adaptive ray tracing technique in modelling indoor radio wave propagation. As compared with conventional ray tracing approach, the presented ray tracing approach offers an optimized method to trace the travelling radio signal by introducing flexibility and adaptive features in ray launching algorithm in modelling the radio wave for indoor scenarios. The simulation result was compared with measurements data for verification. By analyzing the results, the proposed adaptive technique showed a better improvement in simulation time, power level and coverage in modelling the radio wave propagation for indoor scenario and may benefit in the development of signal propagation simulators for future technologies.
Similar to New modeling approach of laser communication in constellation and through atmospheric disturbances (20)
Square transposition: an approach to the transposition process in block cipherjournalBEEI
The transposition process is needed in cryptography to create a diffusion effect on data encryption standard (DES) and advanced encryption standard (AES) algorithms as standard information security algorithms by the National Institute of Standards and Technology. The problem with DES and AES algorithms is that their transposition index values form patterns and do not form random values. This condition will certainly make it easier for a cryptanalyst to look for a relationship between ciphertexts because some processes are predictable. This research designs a transposition algorithm called square transposition. Each process uses square 8 × 8 as a place to insert and retrieve 64-bits. The determination of the pairing of the input scheme and the retrieval scheme that have unequal flow is an important factor in producing a good transposition. The square transposition can generate random and non-pattern indices so that transposition can be done better than DES and AES.
Hyper-parameter optimization of convolutional neural network based on particl...journalBEEI
The document proposes using a particle swarm optimization (PSO) algorithm to optimize the hyperparameters of a convolutional neural network (CNN) for image classification. The PSO algorithm is used to find optimal values for CNN hyperparameters like the number and size of convolutional filters. In experiments on the MNIST handwritten digit dataset, the optimized CNN achieved a testing error rate of 0.87%, which is competitive with state-of-the-art models. The proposed approach finds optimized CNN architectures automatically without requiring manual design or encoding strategies during training.
Supervised machine learning based liver disease prediction approach with LASS...journalBEEI
In this contemporary era, the uses of machine learning techniques are increasing rapidly in the field of medical science for detecting various diseases such as liver disease (LD). Around the globe, a large number of people die because of this deadly disease. By diagnosing the disease in a primary stage, early treatment can be helpful to cure the patient. In this research paper, a method is proposed to diagnose the LD using supervised machine learning classification algorithms, namely logistic regression, decision tree, random forest, AdaBoost, KNN, linear discriminant analysis, gradient boosting and support vector machine (SVM). We also deployed a least absolute shrinkage and selection operator (LASSO) feature selection technique on our taken dataset to suggest the most highly correlated attributes of LD. The predictions with 10 fold cross-validation (CV) made by the algorithms are tested in terms of accuracy, sensitivity, precision and f1-score values to forecast the disease. It is observed that the decision tree algorithm has the best performance score where accuracy, precision, sensitivity and f1-score values are 94.295%, 92%, 99% and 96% respectively with the inclusion of LASSO. Furthermore, a comparison with recent studies is shown to prove the significance of the proposed system.
A secure and energy saving protocol for wireless sensor networksjournalBEEI
The research domain for wireless sensor networks (WSN) has been extensively conducted due to innovative technologies and research directions that have come up addressing the usability of WSN under various schemes. This domain permits dependable tracking of a diversity of environments for both military and civil applications. The key management mechanism is a primary protocol for keeping the privacy and confidentiality of the data transmitted among different sensor nodes in WSNs. Since node's size is small; they are intrinsically limited by inadequate resources such as battery life-time and memory capacity. The proposed secure and energy saving protocol (SESP) for wireless sensor networks) has a significant impact on the overall network life-time and energy dissipation. To encrypt sent messsages, the SESP uses the public-key cryptography’s concept. It depends on sensor nodes' identities (IDs) to prevent the messages repeated; making security goals- authentication, confidentiality, integrity, availability, and freshness to be achieved. Finally, simulation results show that the proposed approach produced better energy consumption and network life-time compared to LEACH protocol; sensors are dead after 900 rounds in the proposed SESP protocol. While, in the low-energy adaptive clustering hierarchy (LEACH) scheme, the sensors are dead after 750 rounds.
Plant leaf identification system using convolutional neural networkjournalBEEI
This paper proposes a leaf identification system using convolutional neural network (CNN). This proposed system can identify five types of local Malaysia leaf which were acacia, papaya, cherry, mango and rambutan. By using CNN from deep learning, the network is trained from the database that acquired from leaf images captured by mobile phone for image classification. ResNet-50 was the architecture has been used for neural networks image classification and training the network for leaf identification. The recognition of photographs leaves requested several numbers of steps, starting with image pre-processing, feature extraction, plant identification, matching and testing, and finally extracting the results achieved in MATLAB. Testing sets of the system consists of 3 types of images which were white background, and noise added and random background images. Finally, interfaces for the leaf identification system have developed as the end software product using MATLAB app designer. As a result, the accuracy achieved for each training sets on five leaf classes are recorded above 98%, thus recognition process was successfully implemented.
Customized moodle-based learning management system for socially disadvantaged...journalBEEI
This study aims to develop Moodle-based LMS with customized learning content and modified user interface to facilitate pedagogical processes during covid-19 pandemic and investigate how teachers of socially disadvantaged schools perceived usability and technology acceptance. Co-design process was conducted with two activities: 1) need assessment phase using an online survey and interview session with the teachers and 2) the development phase of the LMS. The system was evaluated by 30 teachers from socially disadvantaged schools for relevance to their distance learning activities. We employed computer software usability questionnaire (CSUQ) to measure perceived usability and the technology acceptance model (TAM) with insertion of 3 original variables (i.e., perceived usefulness, perceived ease of use, and intention to use) and 5 external variables (i.e., attitude toward the system, perceived interaction, self-efficacy, user interface design, and course design). The average CSUQ rating exceeded 5.0 of 7 point-scale, indicated that teachers agreed that the information quality, interaction quality, and user interface quality were clear and easy to understand. TAM results concluded that the LMS design was judged to be usable, interactive, and well-developed. Teachers reported an effective user interface that allows effective teaching operations and lead to the system adoption in immediate time.
Understanding the role of individual learner in adaptive and personalized e-l...journalBEEI
Dynamic learning environment has emerged as a powerful platform in a modern e-learning system. The learning situation that constantly changing has forced the learning platform to adapt and personalize its learning resources for students. Evidence suggested that adaptation and personalization of e-learning systems (APLS) can be achieved by utilizing learner modeling, domain modeling, and instructional modeling. In the literature of APLS, questions have been raised about the role of individual characteristics that are relevant for adaptation. With several options, a new problem has been raised where the attributes of students in APLS often overlap and are not related between studies. Therefore, this study proposed a list of learner model attributes in dynamic learning to support adaptation and personalization. The study was conducted by exploring concepts from the literature selected based on the best criteria. Then, we described the results of important concepts in student modeling and provided definitions and examples of data values that researchers have used. Besides, we also discussed the implementation of the selected learner model in providing adaptation in dynamic learning.
Prototype mobile contactless transaction system in traditional markets to sup...journalBEEI
1) Researchers developed a prototype contactless transaction system using QR codes and digital payments to support physical distancing during the COVID-19 pandemic in traditional markets.
2) The system allows sellers and buyers in traditional markets to conduct fast, secure transactions via smartphones without direct cash exchange. Buyers scan sellers' QR codes to view product details and make e-wallet payments.
3) Testing showed the system's functions worked properly and users found it easy to use and useful for supporting contactless transactions and digital transformation of traditional markets. However, further development is needed to increase trust in digital payments for users unfamiliar with the technology.
Wireless HART stack using multiprocessor technique with laxity algorithmjournalBEEI
The use of a real-time operating system is required for the demarcation of industrial wireless sensor network (IWSN) stacks (RTOS). In the industrial world, a vast number of sensors are utilised to gather various types of data. The data gathered by the sensors cannot be prioritised ahead of time. Because all of the information is equally essential. As a result, a protocol stack is employed to guarantee that data is acquired and processed fairly. In IWSN, the protocol stack is implemented using RTOS. The data collected from IWSN sensor nodes is processed using non-preemptive scheduling and the protocol stack, and then sent in parallel to the IWSN's central controller. The real-time operating system (RTOS) is a process that occurs between hardware and software. Packets must be sent at a certain time. It's possible that some packets may collide during transmission. We're going to undertake this project to get around this collision. As a prototype, this project is divided into two parts. The first uses RTOS and the LPC2148 as a master node, while the second serves as a standard data collection node to which sensors are attached. Any controller may be used in the second part, depending on the situation. Wireless HART allows two nodes to communicate with each other.
Implementation of double-layer loaded on octagon microstrip yagi antennajournalBEEI
This document describes the implementation of a double-layer structure on an octagon microstrip yagi antenna (OMYA) to improve its performance at 5.8 GHz. The double-layer consists of two double positive (DPS) substrates placed above the OMYA. Simulation and experimental results show that the double-layer configuration increases the gain of the OMYA by 2.5 dB compared to without the double-layer. The measured bandwidth of the OMYA with double-layer is 14.6%, indicating the double-layer can increase both the gain and bandwidth of the OMYA.
Exact secure outage probability performance of uplinkdownlink multiple access...journalBEEI
In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at the physical layer. In the considered system model, the base station acts a relay to allow two users at the left side communicate with two users at the right side. By considering imperfect channel state information (CSI), the secure performance need be studied since an eavesdropper wants to overhear signals processed at the downlink. To provide secure performance metric, we derive exact expressions of secrecy outage probability (SOP) and and evaluating the impacts of main parameters on SOP metric. The important finding is that we can achieve the higher secrecy performance at high signal to noise ratio (SNR). Moreover, the numerical results demonstrate that the SOP tends to a constant at high SNR. Finally, our results show that the power allocation factors, target rates are main factors affecting to the secrecy performance of considered uplink-downlink NOMA systems.
Design of a dual-band antenna for energy harvesting applicationjournalBEEI
This report presents an investigation on how to improve the current dual-band antenna to enhance the better result of the antenna parameters for energy harvesting application. Besides that, to develop a new design and validate the antenna frequencies that will operate at 2.4 GHz and 5.4 GHz. At 5.4 GHz, more data can be transmitted compare to 2.4 GHz. However, 2.4 GHz has long distance of radiation, so it can be used when far away from the antenna module compare to 5 GHz that has short distance in radiation. The development of this project includes the scope of designing and testing of antenna using computer simulation technology (CST) 2018 software and vector network analyzer (VNA) equipment. In the process of designing, fundamental parameters of antenna are being measured and validated, in purpose to identify the better antenna performance.
Transforming data-centric eXtensible markup language into relational database...journalBEEI
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2008 BUILDING CONSTRUCTION Illustrated - Ching Chapter 02 The Building.pdf
New modeling approach of laser communication in constellation and through atmospheric disturbances
1. Bulletin of Electrical Engineering and Informatics
Vol. 10, No. 4, August 2021, pp. 2088~2099
ISSN: 2302-9285, DOI: 10.11591/eei.v10i4.2792 2088
Journal homepage: http://beei.org
New modeling approach of laser communication in constellation
and through atmospheric disturbances
Hachemi Chenina1
, Djamel Benatia2
, M’Hamed Boulakroune3
1
Electronic Department, Faculty of Technology, University of Batna 2, Algeria
2
Laboratoire d'Électronique Avancée (LEA), Electronic Department, Faculty of Technology, University Batna 2, Algeria
3
Laboratory of Electrical Engineering Polytechnic Constantine, Electrical and Automatic Department, National
Polytechnic School of Constantine, Algeria
Article Info ABSTRACT
Article history:
Received Jan 10, 2021
Revised Apr 29, 2021
Accepted Jun 24, 2021
Laser communication between satellites in the constellation and from the
satellites to ground stations offers a gigantic data rate for the users. This
principal advantage drives telecom companies to develop this technology to
use it like a carrier signal, the most disadvantage of this technology is the need
to very complicated pointing systems between the transmitter and the receiver
due to a very small beam divergence, continually moving of satellites in orbits
and the distance between the satellites (tens of thousands of kilometers). The
laser beam suffers continuously from several factors like atmospheric
turbulences, internal and external vibrations. All these factors lead to an
increase in the bit errors rate and cause degradation in the communication
quality. This paper deals with a new method of modelisation of external
effects in transmission of signal light from a ground station to the satellite
through atmospheric disturbances. Indeed, an in-depth investigation, of the
influences of satellite vibrationsinlaser signal transmission between satellites
constellation, has been conducted by studying the effect of the intensity of
vibrations on the optical signal amplitude. Some solutions are proposed to
improve the efficiency of optical satellites communications.
Keywords:
Atmospheric turbulence
Inter-satellite laser-
communication
Optical communication
Optical satellites constellation
Pointing systemes
This is an open access article under the CC BY-SA license.
Corresponding Author:
Hachemi Chenina
Electronic Department, Faculty of Technology
University of Batna 2
05000 Batna, Algeria
Email: chenina31@yahoo.fr
1. INTRODUCTION
Using laser beam in optical satellites communication is thought to be the most important technology
because of its advantages vs the radio frequency links, such as license-free frequency band, rapid and simple
implementation, adaptable transmitter and receiver design, and extremely reliable sensitive data transfer [1],
Installation costs are modest, energy requirements are modest, the beam size is narrow, and the bandwidth is
wide. This approach allows people to communicate without interfering from electromagnetic fields [2], [3].
Given all these advantages, we use laser beams in satellite communications systems (up-link, down-link,
constellation of satellites and inter-satellite link). Data is sent from one spacecraft to another orbiting in the
same or separate orbits using free space/vacuum as the propagation medium and optically modulated carrier
signals in inter-satellite optical wireless communication (IsOWC) connections. M. Singh, and J. Malhotra [4]
inter-satellite connections (ISLs) are critical for maintaining a modest number of ground stations. Without the
use of ground stations, traffic can be diverted from spacecraft to another one using ISLs. The iridium system
is an operating LEO satellite networks of RF-ISLs [5]. The laser beam on its way from the transmitter to the
2. Bulletin of Electr Eng & Inf ISSN: 2302-9285
New modeling approach of laser communication in constellation … (Hachemi Chenina)
2089
receiver suffers from many effects that increase the BER and thus decrease the efficiency of the
communication system. These effects include atmospheric disturbances in the atmosphere that affect the
ascending signal to the satellite, when the signal reaches the satellite and moves between the constellations of
satellites, it is exposed to many factors that affect the quality of communication, this factors include internal
and external vibrations.
The air turbulence due to changes occurred in temperature and atmospheric pressure. According to
the theory of Kolmogorov successive energy, it produces cells in the formation of a turbulent, called
"vortices", which have different sizes and refractive indices [6]. S. Liu, j. Yang, X. Guo, et al. [7] reports an
algorithm of arranging ISLs in the laser/radio hybrid network. A review on different difficulties looked by
free space optical (FSO) communications system for inter-satellite links has been deliberated in [8]. C. Wang
et al. [9], the author present detailed analysis of ISL observations. In particular, he implement observation
model refinements and highlight the contribution of ISL measurements. M. Toyoshima [10] introduces the
trends of space laser communications for constellations. G. Curzi et al. [11] the author aim at the perspective
of matching technical needs and technology availability for large constellations, while providing at the same
time a detailed survey of the up coming satellite constellations, By introducing a representative list of RSSC
missions, I. Sanad et al. [12] provides an overview of what is currently understood about satellites networks
configurations and orbit types used for satellite remote sensing constellation (RSSC) missions. The work in
[13] establish a model for a trusted device quantum key distribution (QKD) spacecraft in low earth orbit
(LEO) and test its efficacy in various network configurations examine the importance of inter-satellite QKD
connections in addition. T. Savitri et al. [14] describe a method to address a complex coverage area by using
sparse satellite constellation design with a limited coverage capability. The results of [15] show how the on-
axis scintillation index of annular Gaussian beams and BER change in vertical directions for laser satellite
communications networks. The performance of optical wireless system that employs M-ary PPM of a
Gaussian beam, in terms of BER when the optical wireless system is operated in an anisotropic non-
Kolmogorov turbulent atmosphere are specified in Y. Ata et al [16]. For GEO and MEO laser satellite
connections, a modern and theoretical time series synthesizer of the log-amplitude of the laser signal due to
scintillation is proposed in [17]. H. Singh et al. [18] presents turbulent atmospheric channels with zero and
non zero boresight pointing errors and elucidates the effect of phase noise on performance of FSO
communication. M. Yasser et al. [19] presents the FSO link system and channel models. Mathematical
analysis and close-form expressions for SER and outage probability are proposed.
In this work, for the first time, we report new modeling approach of laser communication in
constellation and through atmospheric disturbances in the communication bitween ground station and
satellite through Atmospheric week and strong turbulances and bitween the satellites in constellations
including a modelation of internal vibrations of the satellite sub-systems in a constellations and studing the
effects of this vibrations on the quality of the optical signal (SNR, BER). With the suggestion of some
possible solutions to reduce the negative effects of these vibrations.
The paper is organized as follows, various atmospheric effects like, beam broadening, turbidity,
astronomical refraction and scintillation are discussed in section 2, atmospheric turbulence model are
presented in section 3, laser communications in constellations of satellies under the effects of the internal
satellites vibrations are discussed in section 4, simulation results are discussed in section 5, a proposed
solutions to mitigate the undesirable effects of vibrations are presented in section 6, finally, the conclusion is
presented in section 7.
2. LASER COMMUNICATION THROUGH ATMOSPHERIC CHANNEL
2.1. Description of the atmospheric turbulence
There are many previous studies that dealt in depth with the chemical components of the atmosphere
and the effects of wind and sea-level rise on the spread of electromagnetic waves and laser beams [2], [20].
The atmosphere is a complicated structure with a high level of sophistication. It is clear that the whole range
of processes that constitute the atmosphere and its relationship with laser radiation must be known before
useful optical devices for activity in the atmosphere can be planned. The atmosphere chemical composition
has been well explained in the reference [20], [21]. The atmospheric turbidity reported in [22]. References
[23]-[26] explain the astronomical refraction and air turbulence.
2.2. The effect of turbulence on the optical beam
Most research employed the "frozen" turbulence hypothesis to simulate laser radiation in the
atmosphere [23]. The approach includes the assumption that the time change at any place is produced by the
uniform beam movement of the entire atmosphere due to prevailing wind [23], [27], [28]. The evolution of
turbulence in the atmosphere causes changes in the internal structure of the atmosphere. The evolution of
turbulence through time causes changes in the internal structure of the atmosphere, which are ignored.
3. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 10, No. 4, August 2021 : 2088 – 2099
2090
2.2.1. Beam broadening
Let us consider the beam size in free space as W and the intensity at the distance L is given by the
formula: (see Figure 1)
𝐼(𝑥, 𝜌) = 𝐼0 (
𝑊0
𝑊
)
2
𝑒𝑥𝑝 [−
2𝜌2
𝑊2 ] (1)
where W is the beam width in free space and Wb is the beam width in turbulence [23], [29], Io is the intensity
of the incident beam on the beam axis, Wo is the beam size at the transmitter, 𝜌 is the transverse distance
from the beam axis
Figure 1. Beam spread
The beam size W for a collimated beam in free space is given by:
𝑊2
= 𝑊0
2
+ (
2𝐿
𝑘𝑊0
)
2
(2)
The beam size Wb in the turbulence is given by:
𝑊𝑏
2
=
𝑊2
2 ∫ 𝑒𝑥𝑝[−𝑡2−(1
2
⁄ )𝐷𝑠𝑡5 3
⁄ ]𝑡𝑑𝑡
∞
0
(3)
2.2.2. Spatial coherence
The loss of spatial coherence on the laser beam is another significant consequence of disturbance in
the open skies. Nonlinear phase variations can result from uneven refractive indices at wide scales. Thereby
reducing the coherence of the wave front radiation. The structure function of the phase fluctuation 𝐷𝑠(𝜌1, 𝜌2)
is defined as [23], [30]:
𝐷𝑠(𝜌1, 𝜌2) = 𝐸[|𝑠(𝜌1) − 𝑠(𝜌2)|2] (4)
where 𝜌1and 𝜌2 are position vectors in the plane of observation across the beam and 𝑠(. )is the phase at that
point. For weak turbulence, [31] gives a simple result for the phase structure function
𝐷𝑠(0, 𝜌) = 2.91𝑏1𝐶𝑛
2
𝑧𝜌5/3
(5)
where the value of b1 ranges from 1.0 for a plane wave to 0.375 for a spherical wave.
The phase correlation between the two points 𝜌1 and 𝜌2 of the wave-front decreases with the distance
𝜌 = |𝜌1 − 𝜌2|. For plane waves or spherical waves, the coherence can be expressed as:
𝛾(𝑧, 𝜌) = 𝑒𝑥𝑝 [− (
𝜌
𝜌0
)
5/3
]
(6)
where 𝜌0is the radius of phase coherence which is presented as:
𝜌0 = (𝑏2𝐶𝑛
2
𝑘2
𝑧2)−3/5
(7)
4. Bulletin of Electr Eng & Inf ISSN: 2302-9285
New modeling approach of laser communication in constellation … (Hachemi Chenina)
2091
where 𝑏2=1.45 for a plane wave and 0.55 for a spherical wave. When 𝜌 ≥ 𝜌0, the random phase angle
variation is greater than 𝜋, It is thought that the wave-front has lost its spatial coherence [23], [30].
2.3. Effect of turbidity on optical radiation
Light is absorbed and scattered by atmospheric elements such as gases and dust. As a result, the
turbidity of the atmosphere must be considered when designing an effective laser device, and must consider
the reduction of the direct beam energy when the light propagates in the atmosphere.
2.3.1. Absorption and scattering loss
Water, carbon dioxide, and ozone molecules are the primary atmospheric absorbers [32]. The
absorption of light by the atmosphere is a wavelength-dependent phenomenon. In databases like MORTRAN,
the wavelength dependence of attenuation under various weather situations is usually provided [33].
2. ATMOSPHERIC TURBULENCE MODEL
Turbulence is caused by random fluctuations in the atmosphere's refractive indices. The temperature
difference between the atmosphere, the ground, and the ocean produces the change in refractive index, which
causes airflow and wind to enter the top layer of the atmosphere. Temperature, pressure, length of wave, and
humidity all affect the fixed refractive index 𝑛0 [34].
𝑛0 ≈ 1 +
77p
𝑇
[1 +
7.53.10−3
𝜆2 − 7733
q
𝑇
] 10−6
(8)
where q is specific humidity (gm3
), 𝜆 is wavelength, T is temperature (K), p is air pressure (millibars).
When dealing with random motion of the refractive indices, Kolmogorov's model is commonly
applied. The refractive indices, according to this idea, is the sum of fixed and variable components [35].
𝑛𝑇(𝑟) = 𝑛0 + 𝑛(𝑟); Where n0 is the median indice of refraction, r is the position in space, and 𝑛(𝑟) is the
random component produced by the spatial variation of pressure, temperature and humidity. The basic
statistical parameter is the spatial cross-correlation of the refractive index, which is defined as [36]:
Γ𝑛(𝑟1, 𝑟2) = Ε[𝑛(𝑟1), 𝑟(2)]
(9)
where Ε[ ] Signifies the expected value.
The power spectral density is the three-dimensional Fourier transform of the spatial correlation of
the refractive index, given by the references [37]-[39] as:
Φ(𝐾) = 0.033𝐶𝑛
2
𝐾−11 3
⁄
(10)
where 𝐶𝑛
2
is the indice of refraction [17], and K satisfies the inequality 2𝜋 𝐿0 < 𝐾 < 2𝜋/𝑙0
⁄ ; 𝑙0 is the internal
limit and L0 is the external limits.
The inertial range of the Kolmogorov spectrum defined by (11) is limited by internal and external
constraints. 𝐶𝑛
2
Differs between 10−13
𝑚−2/3
for severe disturbances to 10−17
𝑚−2/3
of weak disturbances.
Empirical data forms the basis of a model for determining 𝐶𝑛
2
values, such as the sum of highly correlated
indices used in reference [36].
𝐶𝑛
2(ℎ) = 𝐴 𝑒𝑥𝑝 (−
ℎ
𝐻𝐴
) + 𝐵 𝑒𝑥𝑝 (−
ℎ
𝐻𝐵
) + 𝐶ℎ10
𝑒𝑥𝑝 (−
ℎ
𝐻𝐶
) + 𝐷 𝑒𝑥𝑝 (−
(ℎ−𝐻𝐷)2
2𝑑𝐶
2 ) (11)
where A is the coefficient of turbulence intensity on the surface (boundary layer), HA is the altitude of its 1/e
attenuation, B and HB denote the troposphere disturbance, C and HC denote the highest point of the
troposphere disturbance level, D and HD define an isolated turbulent layer, and dc is the thickness of the
layer.
A random Maxwell wave equation is used to compare the index of refraction function with the
electromagnetic model. Rytov's approach achieves the simplification of Maxwell's equations [40], [41]. The
field is supposed to be a combination of the free space field and the random complex amplitude transmittance
representing the field disturbance.
𝑙0 < √𝑍𝜆 < 𝐿0 where λ is the wavelength and the turbulent coherence diameter d0 can be
approximated by reference [40], [41]. 𝑑0 < √𝑍𝜆. We think of the downlink as a plane wave because most of
5. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 10, No. 4, August 2021 : 2088 – 2099
2092
the path of the laser beam travels through space and is only affected by turbulence when it approaches earth.
References [31], [40], [41] give the covariance of plane waves as:
𝜎𝑋
2(𝑍) = 0.56 (
2𝜋
𝜆
)
7 6
⁄
∫ 𝐶𝑛
2(𝑥)(𝑍 − 𝑥)5/6
𝑑𝑥
𝑍
0
(12)
The density distribution function of X is normal, as shown [40]:
𝑓𝑋(𝑋) =
1
√2𝜋𝜎𝑥
𝑒𝑥𝑝 (−
𝑋−𝐸[𝑋]2
2𝜎𝑋
2 ) (13)
Normalized received power is related to logarithmic amplitude X:
𝐼 = 𝑒𝑥𝑝(2𝑋 − 2𝐸[𝑋]) (14)
After studying the spread of the laser beam in the atmosphere and analyzing the effects of
atmosphere components on the light signal, the signal now reaches the satellite and travels through a
constellation of satellites to reach the satellite located above the receiver. In this part, we will analyze the
transmission of this signal between the satellites, and the various effects of the light beam.
3. NETWORK COMMUNICATION MODEL
A satellite constellation is a set of related satellites that operate together to form a network. The
LEO constellation of satellites is configured to act as a network to provide more coverage [42], [43]. The
considered optical inter-satellite network model includes transmitter satellite, repeater satellites, and receiver
satellite all networked together [44].
4.1. Signal model
We arrive at a model in this subsection that connects the laser signal transmitted by the first
spacecraft in the constellation to the signal received by the last spacecraft. The optical signal obtained by the
constellation's second spacecraft is:
PR = K . L (15)
where
𝐾 = 𝜂𝑇. 𝜂𝑅 (
𝜆
4.𝜋.𝑍
)
2
. 𝐺𝑅. 𝐺𝑇. 𝑃𝑇 (16)
The optical signals received by satellite (n+1) in the network is [45]
PR(n + 1) = ∏ KiLi
n
i=1 (17)
with:
𝐾𝑖 = 𝐺𝑖𝜂𝑇𝑖𝜂𝑅𝑖+1 (
𝜆
4𝜋𝑍𝑖
)
2
𝐺𝑇𝑖𝐺𝑅𝑖+1𝑖 = 2,3, … , 𝑛, (18)
Where 𝐺𝑖 is the gain of the network's spacecraft relays i. 𝑃𝑇 is the optical strength of the emitter, Zi is the
spacing among spacecraft i and i+1. n represent the number of spacecraft in the constellation, 𝜂𝑇𝑖 is the
photonics efficiency of the emitter spacecraft i in the constellation and 𝜂𝑅𝑖 is the photonics efficiency of the
reception spacecraft i in the constellation.
The targeting loss factor is determined as [46]:
𝐿𝑖 = exp (−𝐺𝑇𝑖
𝜃𝑖
2
) (19)
where 𝜃𝑖 is the angle of radial pointing inaccuracy.
The transmitter gain of satellite i in the network is:
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𝐺𝑇𝑖 = (
𝜋𝐷𝑇𝑖
𝜆
)
2
(20)
where 𝐷𝑇𝑖 is the size of the emitter aperture in the i satellite in the constellations.
The receiver gain of the i satellite in the satellites constellation is [45]:
𝐺𝑅𝑖 = (
𝜋𝐷𝑅𝑖
𝜆
)
2
(21)
where 𝐷𝑅𝑖 is the size of the receiver aperture in the i satellite in the constellations. if all satellites are the same
𝐺𝑇𝑖 = 𝐺𝑇𝑗 = 𝐺𝑇𝑖∀𝑖, 𝑗 (22)
The optical signals received by satellite (n+1) in the network is
𝑃𝑅(𝑛 + 1) = exp (−𝐺𝑇 ∑ 𝐺𝑇𝑖𝜃𝑖
2
𝑛
𝑖=1 ) ∏ 𝐾𝑖
𝑛
𝑖=1
(23)
From (24)
𝑃𝑅(𝑛 + 1) = exp (−𝐺𝑇𝑋) ∏ 𝐾𝑖
𝑛
𝑖=1 (24)
where
𝑋 = ∑ 𝜃𝑖
2
𝑛
𝑖=1 (25)
Each 𝜃𝑖 contains two normal processes (azimuth and elevation), so X includes 2n normal processes.
The process distribution composed of the sum of squares of normal processes with equal variances is chi-
square. If all satellites are the same, the standard deviation of the radial pointing error angle of all satellites is
equal to [47]:
𝜎𝑖 = 𝜎𝑗 = 𝜎1 = 𝜎𝑋 ∀𝑖, 𝑗. (26)
Therefore X is a chi-square distribution with probability density:
𝑓(𝑋) = 𝑎𝑋−1+𝑛
exp (−
𝑋
2𝜎1
2) 𝑈(𝑋) (27)
where
𝑎 =
1
(𝜎1√2)𝑚2𝑛Γ(n)
(28)
The gamma function is:
Γ(x) = ∫ tx−1
exp(−t) dt 1 ≤ x ≤ 2
∞
0
(29)
The average optical power received in the n satellite is
𝑆 = 𝑎 ∏ 𝐾𝑖 ∫ 𝑥−1+𝑛
𝑒𝑥𝑝 (−𝐺𝑇𝑥
𝑥
2𝜎1
2) 𝑑𝑥
∞
0
𝑛
𝑖=1 (30)
After solving (30):
𝑆 =
∏ 𝐾𝑖
𝑛
𝑖=1
(𝐺𝑇2𝜎1
2+1)
𝑛 (31)
3.1. Performance models
The SNR model is [47]:
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𝑆𝑁𝑅 = ∫ …
∞
0
∫
[𝑅𝑃𝑅(𝜃1…𝜃𝑛)]2
𝜎𝑁𝑇
2 (𝜃1…𝜃𝑛)
𝑓(𝜃1) …
∞
0
𝑓(𝜃𝑛)𝑑𝜃1 … 𝑑𝜃𝑛 (32)
where R is the response of the detector at the receiver satellite.
To simplify the (32), We suppose that the primary source of noise is in the constellation's final satellite. Then
(32) becomes:
𝑆𝑁𝑅 ≈
𝑅2𝑃𝑇
2
𝜎𝑁2
2 𝐺2
2 ∫ … ∫ [𝐾2
2𝑛
𝑒𝑥𝑝(−2𝐺𝑇 ∑ 𝜃𝑖
2
𝑛
𝑖=1 )]𝑓(𝜃1) … 𝑓(𝜃𝑛)
∞
0
∞
0
𝑑𝜃1 … 𝑑𝜃𝑛 (33)
Repeating the same procedure in (12) to (18) for (31)
𝑆𝑁𝑅 ≈
𝑅2𝑃𝑇
2
𝜎𝑁2
2 𝐺2
2
𝐾2
2𝑁
(1+4𝐺𝑇𝜎1
2)
𝑛 (34)
The noise-to-signal ratio NSR to obtain a closed form [47]:
𝑁𝑆𝑅 =
𝜎𝑁2
2
𝐺2
2
𝑅2𝑃𝑇
2 ∫ … ∫ [
1+𝐾2
2 exp(−2𝐺𝑇𝜃𝑛
2) ∏ 𝐾𝑖+1
2
exp(−2𝐺𝑇 ∑ 𝜃𝑖+1
2
𝑛−1
𝑖=1 )
𝑛−1
𝑖=1
𝐾2
2𝑛𝑒𝑥𝑝(−2𝐺𝑇 ∑ 𝜃𝑖
2
𝑛
𝑖=1 )
]
∞
0
∞
0
𝑓(𝜃1) … 𝑓(𝜃𝑛)𝑑𝜃1 … 𝑑𝜃𝑛(35)
Repeating the procedure in (35):
𝑁𝑆𝑅 =
𝜎𝑁2
2
𝐺2
2
𝑅2𝑃𝑇
2 [
1
𝐾2
2𝑛(1−4𝐺𝑇𝜎1
2)
𝑛 + ⋯ +
1
𝐾2
2(1−4𝐺𝑇𝜎1
2)
] (36)
In (35) provides us another factor for analyzing constellation efficiency.
4. RESULTS AND DESCUSSIONS
In this section, we give some results based in a parameters showen in Table 1. From the Figure 2,
we can assume that the spatial coherence decreases when the altitude of the transmitter increases and
decreases also with the strongest of the turbulence, for a 𝐶𝑛
2
=10-9
for weak turbulence the spatial coherence is
greater than the strong turbulence with Cn
2
=10-7
; so the altitude from the sea level and the strongest of the
turbulence degrade the coherence of the propagating wave front. This leads to deterioration in the receiver,
the beam pattern begins to decompose into different regions of high and low intensity. Absence of beam
efficiency at the receptor can result in areas of spontaneous variability with low signal strength for
sufficiently long path lengths and high optical turbulence amplitude, resulting in severe signal attenuation.
Table 1. Parameters used in this analyse
Parameter Name Parameter Symbol Parameter Value
Link range L ≈8x102
Km
Optical received signal PR -
Distance between the satellites Z 40,000 Km
Electronicbandwidth B 2 GHz
Transmitter/receiveroptics efficiency 𝜂𝑇, 𝜂𝑅 80%
Wavelength Λ 0.635 μm
Turbulence force 𝐶𝑛
2
10-7
Altitude A -
Received light intensity probability 𝑃𝑤(𝐼) -
Number of satellites in the constellation N 20
The radial pointing error angle's 𝜎𝑖 -
The size of the receiver aperture in the i satellite in the constellations 𝐷𝑅𝑖 0.2m
Figure 3 illustrates how the magnitude of disturbance 𝐶𝑛
2
varies depending on the channel's different
parameters, such as wind velocity, height, and environmental conditions. The 𝐶𝑛
2
was estimated between 0
and 20 km in this study and not greater since the value of 𝐶𝑛
2
is minimal at high latitudes. The intensity force
is calculated using various altitudes and wind speeds. Wind speeds shear at the ground, affecting the
atmosphere's refractive index and resulting in substantial disturbance output. Low turbulence is defined as a
wind speed of 9 m/s, whereas moderate turbulence is defined as a wind speed of 18 m/s. This graph clearly
8. Bulletin of Electr Eng & Inf ISSN: 2302-9285
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shows that the highest value of 𝐶𝑛
2
is located near to the surface, and that as altitude grows, its value
decreases, and this negatively affects the quality of the spread of the light signal.
Figure 2. Spatial coherence vs. altitude (Km) and turbulence
Figure 3. The force of turbulence vs. the altitude and the wind speed
From the Figure 4, we notice that scintillation (log-irradiation) is completely related to the angle of
Zenith as shown in Figure 4 so any change, even very small, causes a complete loss of optical radiation and
thus a explains the basic advantages of the use of lasers in communication. This is the great resistance against
interference, which gives great safety to transmit the signal from the transmitter to the receiver. This result
also explains the need for a very accurate tracking system that ensures connectivity in the event of movement
and continuous vibration of the satellites.
Figure 4. Log-irradiance as a function of zenith angle
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From Figure 5, we notice that the wavelength considerably affects the scintillation the increase in
the wavelength causes a decrease in the scintillation and the decreasing in the wavelength causes an
increasing in the scintillation. We also note that the wind speed affects scintillation, if the wind speed
increases, the scintillation decreases and if the wind speed decreases, the value of the scintillation increases.
This is due to the effect of wind speed on the strength of the air turbulence. Log-irradiance has a good value
at a wavelength of less than 100 μm, and after the wavelength 1 mm it becomes negligible and close to zero.
Figure 5. Log-irradiance vs. wavelength variance "Yura and McKinley model"
The normalized NSR is seen in Figure 6 as a result of the vibration amplitude and the number of
satellites in the constellation; in this case, the spacecrafts is 20. It is significant to mention that even in the
absence of disturbances; NSR reduces as the constellation expands due to the aggregation of noise in the
passes among spacecraft. The obtained laser light as a function of the vibration amplitude normalized to the
square root of the transmitter gain and the number of spacecraft in the constellation can be seen in Figure 7.
Indeed, as the constellation grows, an increase in vibration intensity greatly reduces the obtained signal,
which is due to the accumulation of vibrations from the first satellite to the last one.
Figure 6. Normalized NSR as a function of vibration
amplitude and number of satellites
Figure 7. The received optical signal as a function of
the vibration amplitude
5. PROPOSED SOLUTIONS TO REDUCE THE EFFECTS OF ATMOSPHERIC TURBULENCE
AND VIBRATIONS ON THE PERFORMANCE OF OPTICAL COMMUNICATION
In this section we propose some solutions briefly to reduce the negative effects of vibrations and
atmospheric turbulence, the proposed solutions to reduce the effects of satellite vibrations on the performance
of optical communications are bandwidth adaptation, power control and channel diversity like what is
mentioned in the references [44], Wavelength diversity and Temporal diversity are discussed in references
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[3], [6], [48], [49], Multiple emitters is mentioned in the reference [50]. In the following we will explain the
most important solution which is: Vibration Isolator.
6.1. Vibration isolator
The techniques of micro-vibration isolation system can be classified into three main categories,
passive, active, semi-active isolation [51]. A mechanical low-pass filter with a classic control mechanism is
used in passive isolation system. Vibration control devices, force actuators, and displacement sensors are
examples of active isolators. Passive isolators are used to minimize vibration distortion in high-frequency
areas where the tuning mechanism's interference reduction capability is inadequate. Active isolators are used
to dampen low frequency and high amplitude sounds that other devices are unable to block.
6. DISCUSSION AND SUMMARY
This article discusses the impact of pointing system vibration and atmospheric turbulence on the
performance of optical communications in up-link and satellite networks. New modeling approach of laser
communication in constellation and through atmospheric disturbances has been developed and compared
with others proposed in the literature. We have demonstrated that The primary constellation performance
parameter is the disturbance intensity, and the constellation size scale is a smaller one.
The results of our simulations show that scintillation (log-irradiation) is completely related to the
angle of zenith, so any change, even very small, causes a complete loss of optical radiation, this result
translates into one of the most important advantages of optical communication mentioned in previous studies
[52], [53]. The wavelength and the wind speed considerably affect the scintillation in our modulation the
increasing in the wavelength and the wind spead causes a decreasing in the scintillation and gradually
approach a value of 0, the reference [15] study also the affect of the propagation distance on the scintillation
index. With an increasing propagation distance, the scintillation index is weakened by the loss of spatial
coherence due to the focusing effect being.
The results of our simulations model show that the rise above the sea surface leads to a decrease in
the strength of the air turbulence from 𝑐𝑛
2
= 10−7.95
for the strong air turbulence to 𝑐𝑛
2
= 10−8.7
for the
medium air turbulence, regardless of the wind speed Until we reach a height of 400 m, the force of the
turbulence change as a function of wind speed also. Compared with result obtained by S. Arnon [35] the
strength of turbulence decrease dramatically from 𝑐𝑛
2
= 10−13
to 𝑐𝑛
2
= 10−17
until the hight of 5000 Km the
wind speed affect also the strongest of turbulence. Finally, in light of these results, we suggested some
solutions to reduce these effects of atmospheric turbulence and the internal satellite vibrations in constellation
to increase the effectiveness of the laser communication system.
7. CONCLUSION
This paper has discussed the laser communication in the constellation of satellites and through
atmospheric disturbance. A new modeling approach of laser communication was developed and simulated
using Matlab software. The study carried out her can be the basis for future analyses of laser communication
through the atmosphere and in the constellations of satellites. This analysis points out that the performance of
the network is determined by the satellite that vibrates the most among the satellites in the network, the laser
communication in space needs a very complicated pointing system.
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