scholarly journals Increasing the Link‐distance of Free‐space Quantum Coherent Communication with Large Area Detectors

2021 ◽  
Vol 2 (1) ◽  
pp. 1-7
Author(s):  
Rupesh Kumar ◽  
Igor Konieczniak ◽  
Gerald Bonner ◽  
Tim Spiller
Keyword(s):  
Free Space ◽  
Large Area ◽  
Link Distance ◽  
Coherent Communication

Improved Performance Analysis of Free Space Optics Communication Link under Rain Conditions using EDFA Pre-amplifier

2018 ◽  
Vol 39 (2) ◽  
pp. 241-246 ◽  
Author(s):  
Mehtab Singh
Keyword(s):  
Performance Analysis ◽  
Free Space ◽  
Weather Conditions ◽  
Fiber Amplifier ◽  
Free Space Optics ◽  
Communication Link ◽  
Erbium Doped Fiber Amplifier ◽  
Space Optics ◽  
Link Distance ◽  
Improved Performance

AbstractFree Space Optics (FSO) also known as Optical Wireless Communication (OWC) is a communication technology in which free space/air is used as the propagation medium and optical signals are used as the information carriers. One of the most crucial factors which degrade the performance of FSO link is the signal attenuation due to different atmospheric weather conditions such as haze, rain, storm, and fog. In this paper, an improved performance analysis of a 2.5 Gbps FSO link under rain conditions has been reported using Erbium-Doped Fiber Amplifier (EDFA) as a pre-amplifier. The results show that the maximum link distance for an FSO link under rain weather conditions with acceptable performance levels (Q$$\sim6$$and BER$$ \le {10^{- 9}})$$in the absence of EDFA pre-amplifier is 1,250 m which increases to 1,675 m with the use of EDFA pre-amplifier.

Mitigation of Atmospheric Turbulences Using Mode Division Multiplexing based on Decision Feedback Equalizer for Free Space Optics

2020 ◽  
Vol 41 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Abdullah Almogahed ◽  
Angela Amphawan ◽  
Yousef Fazea
Keyword(s):  
Free Space ◽  
Minimum Mean Square Error ◽  
Decision Feedback ◽  
Free Space Optics ◽  
Decision Feedback Equalizer ◽  
Free Space Optical ◽  
Space Optics ◽  
Link Distance ◽  
Mode Division Multiplexing ◽  
Simulation Results

AbstractIn mode division multiplexing (MDM) free space optical (FSO) communication system, the atmospheric turbulences such as fog, rain, and haze cause adverse effects on system performance. This paper investigates the mitigation of atmospheric turbulences of FSO using MDM and decision feedback equalizer (DFE) with minimum mean square error (MMSE) algorithm. The implementation of the MMSE algorithm is used to optimize both the feedforward and the feedback filter coefficients of DFE. The proposed system comprises three parallel 2.5Gbit/s channels using Hermite–Gaussian modes. A data rate of 7.5Gbit/s over 40 m, 800 m, 1400 m, and 2km under medium fog, rain, haze, and clear weather, respectively, has been achieved. In addition, it is noticed that the link distance is reduced while increasing the attenuation. The simulation results revealed that a DFE improves the performance MDM FSO system while maintaining high throughput and desired low bit error rate.

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

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

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

Performance analysis of free space optical system incorporating circular polarization shift keying and mode division multiplexing

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Meenu ◽  
Anshu Sharma ◽  
Rahul Malhotra
Keyword(s):  
Circular Polarization ◽  
Free Space ◽  
Heavy Rain ◽  
Weather Conditions ◽  
Detailed Comparison ◽  
Free Space Optical ◽  
Light Rain ◽  
Link Distance ◽  
Mode Division Multiplexing ◽  
Shift Keying

Abstract In this work, a free-space optical (FSO) communication system with the integration of mode division multiplexing and circular polarization shift keying (CpolSK) is proposed at 2 × 40 Gbps using LG00 and LG01 modes. Effects of diverse weather conditions such as clear weather, light rain, moderate rain, heavy rain, thin fog, thick fog, and heavy fog are studied on system performance. Further, a detailed comparison of CpolSK and polarization shift keying (PolSK) is performed at different FSO lengths in terms of log bit error rate. For implementation, analysis, and comparison, Optiwave Optisystem software is used and results show that CpolSK covers 100 km link distance and PolSK limits to 90 km only. Also, LG00 mode performs better than LG01 mode under all weather instabilities in the proposed system.

scholarly journals Novel Multiband Metal-Rimmed Antenna for Wearable Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Bin Liu ◽  
Jianghong Han ◽  
Songhua Hu ◽  
Li Zhang
Keyword(s):  
Numerical Simulations ◽  
Human Body ◽  
Free Space ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Ground Plane ◽  
Large Area ◽  
Specific Absorption ◽  
Additional Resonance ◽  
Feeding Structure

A novel multiband antenna with an unbroken metal rim for wearable applications is presented. In order to achieve a wideband behavior, minimizing at the same time the size of the clearance area on the antenna ground plane, a novel feeding structure is proposed. This is achieved by connecting the metal rim to the ground plane thus allowing generating one lower-frequency resonance without occupying a large area. An additional resonance is then obtained using a suitable shorting patch. In this way, the proposed antenna presents a broadband behavior, while the width of the clearance area on the ground plane is of only 2 mm. The antenna performances in free-space and on a human phantom simulating a human body are analyzed by means of numerical simulations. Finally, the specific absorption rate (SAR) is analyzed to establish the antenna reliability in wearable applications. The experimental results demonstrate superior and stable performances of the metal-rimmed antenna when it is employed in wearable applications.

Investigation on Pointing Error in Multi-Beam Free Space Optical Communication System

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Jayson K. Jayabarathan ◽  
S. Robinson
Keyword(s):  
Fiber Optics ◽  
Wavelength Division Multiplexing ◽  
Communication System ◽  
Free Space ◽  
Maintenance Cost ◽  
Free Space Optical ◽  
Pointing Error ◽  
Wavelength Division ◽  
Link Distance ◽  
The Impact

AbstractFree space optical (FSO) communication has fascinated a lot of attention for a variety of applications in telecommunication area. It is dream of every researcher and telecommunication society to make it a real alternative solution for the last mile problem, to replace fiber optics. FSO is much favored because of its low maintenance cost and deployment time. Pointing error is one of the main challenges in FSO communication system which affects its performance especially at high data links that leads to significant performance degradation. In this paper, the impact of pointing error for multi-beam Hybrid Wavelength Division Multiplexing (HWDM) FSO system is investigated. Then the effect of link distance and Bit Error Rate (BER) are estimated by accounting the pointing error and atmospheric attenuation. The effect of change of link distance is examined while changing the number of beams between the transmitter and receiver as well. In this attempt, the HWDM system is considered by combining eight Dense Wavelength Division Multiplexing (DWDM) channels and four Coarse Wavelength Division Multiplexing (CWDM) channels. In addition, the influences of BER and receiver sensitivity are analyzed for the proposed system by incorporating Erbium Doped Fiber Amplifier (EDFA) at the receiver end. The data rate 2.5 Gbps is considered for both CWDM and DWDM channels for investigation.

scholarly journals Development of a large area InGaAs APD receiver based on an impact ionization engineered detector for free-space lasercomm applications

2012 ◽  
Author(s):  
H. R. Burris ◽  
M. S. Ferraro ◽  
W. T. Freeman ◽  
C. I. Moore ◽  
J. L. Murphy ◽  
...  
Keyword(s):  
Free Space ◽  
Impact Ionization ◽  
Large Area

Key rate estimation of measurement-device-independent quantum key distribution protocol in satellite-earth and intersatellite links

2018 ◽  
Vol 16 (03) ◽  
pp. 1850027 ◽  
Author(s):  
Ahmed Ismael Khaleel ◽  
Shelan Khasro Tawfeeq
Keyword(s):  
Free Space ◽  
Quantum Key Distribution ◽  
Detection System ◽  
Key Distribution ◽  
Earth Satellite ◽  
Measurement Device ◽  
Decoy State ◽  
Link Distance ◽  
State Case ◽  
Measurement Device Independent

In this work, an estimation of the key rate of measurement-device-independent quantum key distribution (MDI-QKD) protocol in free space was performed. The examined free space links included satellite-earth downlink, uplink and intersatellite link. Various attenuation effects were considered such as diffraction, atmosphere, turbulence and the efficiency of the detection system. Two cases were tested: asymptotic case with infinite number of decoy states and one-decoy state case. The estimated key rate showed the possibility of applying MDI-QKD in earth-satellite and intersatellite links, offering longer single link distance to be covered.

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