FSO System Research Articles

On the performance of optical codes for FSO systems using SAC-OCDMA technique to improve system performance

On the performance of optical codes for FSO systems using SAC-OCDMA technique to improve system performance

Performance Analysis of Free Space Optical System Over Inverse Gaussian Gamma Turbulence Channel

ABSTRACTFree space optical (FSO) communication is a proficient technology with potential applications in the next generation of wireless communication. This article evaluates the performance of the FSO system under inverse Gaussian gamma (IGG) fading. A novel closed‐form equation for the cumulative distribution function (CDF) of the received signal‐to‐noise ratio (SNR) is presented by employing an intensity modulation/direct detection (IM/DD) scheme. The analytical expressions for various performance metrics such as outage probability (OP), amount of fading (AOF), and average bit error probability (ABEP) are derived for various digital modulation schemes based on the system's probability density function (PDF) and CDF. Additionally, this article presents an upper bound on OP and asymptotic analysis for the performance metrics to gain deeper insights. It is revealed that the small‐scale eddy turbulence parameter can affect the diversity order by a factor of β/2. The results demonstrate that atmospheric turbulence considerably reduces the system's performance. Finally, Monte‐Carlo simulation is performed to ascertain the correctness of the derived mathematical expressions.

Investigation of urban low-altitude long-range atmospheric links for FSO coherent communication

Due to the complexity of low-altitude atmospheric channel conditions, the commercial application of FSO communication systems is less prevalent than satellite applications. This is mainly because there is a trade-off between achieving system stability through active compensation technology and maintaining low costs. Different application scenarios and atmospheric channel states correspond to different optimal structural parameter selections, which is crucial for low-cost FSO systems without complex compensation mechanisms. Therefore, measuring actual channel conditions is essential. One existing issue is that current research does not sufficiently discuss the connection between theoretical analysis and practical experiments in FSO communication, thus, establishing models and analysis methods is necessary that can accurately predict the performance of actual FSO atmospheric communication systems. We have developed a comprehensive FSO model to evaluate the effects of channel and structural factors on system performance. This model is vital for cost-effective parameter selection in system design and for analyzing actual system performance. Additionally, we established 6.6 km and 12.7 km FSO transmission links in an urban low-altitude environment. Subsequently, we conducted tests on atmospheric attenuation, channel statistical characteristics, and DPSK/QPSK coherent communication performance. Based on the analysis that combines experiments with theory, we have deduced the atmospheric attenuation of FSO links. The channel statistical characteristics provided the statistical properties of the two links under weak, moderate, and strong turbulence, along with fitting curves. Long-term channel statistical experiments indicate that the channel is most stable during the early morning hours of the day, and the 12.7 km communication experiment without turbulence correction technology is only feasible at this time. Furthermore, we presented a method for using theory to evaluate the performance of actual FSO systems in random atmospheric channels.

Performance Enhancement of FEC-Coded 32QAM DMT Signals With Rate-Flexible HCS in FSO Systems

Performance Enhancement of FEC-Coded 32QAM DMT Signals With Rate-Flexible HCS in FSO Systems

Channel estimation of massive MIMO FSO communication system using deep attention residual U-Net

Channel estimation in massive-MIMO FSO systems is critical for ensuring reliable data transmission. However, conventional estimators offer limited benefits due to the computational difficulty of accurately estimating the channel. This paper presents a novel approach to estimate channels using an attention residual U-Net (ARU-Net) architecture which utilizes the advantages of both attention and residual connection. In the simulation, the channel matrix has been represented as a 2D image. The proposed model significantly outperforms traditional channel estimation methods and other deep learning models in terms of MSE (10−5 at 25 dB SNR), especially in atmospheric turbulence and other noises.

Performance analysis of polar-coded FSO systems using turbulence-oriented rotational probabilistic shaping

Performance analysis of polar-coded FSO systems using turbulence-oriented rotational probabilistic shaping

Experimental analysis of reducing outage probability using deep interleaving for long‐distance free space optical systems

AbstractFree space optical communication (FSO) has become a popular research direction due to its high bandwidth, easy deployment, and inherent security. Its channel state is unstable because of atmospheric environment, especially in long‐distance ground transmission system. Interleaving combined with forward error correction coding (FEC) have been utilised to improve the stability of system. However, there is little detailed experimental results of deep interleaving combined with FEC under different atmospheric turbulence intensity over long‐distance FSO system. A deep interleaving with FEC method was designed and implemented on a 7 km long online experiment. The performance of different depth interleaving is analysed under weak and strong atmospheric turbulence state. The experiment results show that deep interleaving performs better under weak turbulence for the larger correlation factor of the channel and the outage probability of the system with deep interleaving can be greatly reduced.

Channel multiplexing of FSO systems based on singular optics approaches

The article proposes two new methods for multiplexing-demultiplexing communication channels in the FSO system, based on singular optics approaches. The first makes use of computer generated vortex holograms installed in the transmitting and receiving modules of the systems, which make it possible to generate and separate communication channels formed by vortex beams with different topological charges. The second method, spatial singular multiplexing, is based on the property of singular beams to restore angular momentum when vortex beams propagate in a medium with physical disturbances. The method uses opaque screens installed in the transmitting block of the system, which diaphragm the vortex beams. As a result of this operation, the centers of the vortices in the receiving part of the system are displaced, which makes it possible to separate the beams that are differently blocked in the transmitting unit. Computer simulation data and experimental results are presented.

Performance of adaptive M-PAM modulation for FSO systems based on end-to-end learning

Performance of adaptive M-PAM modulation for FSO systems based on end-to-end learning

BER Performance analysis of a convolutional coded non-Hermitian OFDM FSO system over strong atmospheric turbulent channel

BER Performance analysis of a convolutional coded non-Hermitian OFDM FSO system over strong atmospheric turbulent channel

Security Analysis of Differential Chaotic Keying in Optical Communication

Space free optical communication (FSO) has the advantages of wide bandwidth resources, less susceptibility to attacks, strong resistance to interference, and low losses. The FSO system itself has high security, with the realization of single photon detection technology, the stealer can obtain information without blocking the beam propagation. So using chaotic encryption methods can further improve the security performance of communication systems. This article uses a gamma gamma turbulence model and utilizes the differential chaotic shift keying (DCSK) method of communication systems to improve the system’s resistance to attacks. The theoretical expression of the system error rate under this model is derived, and the security performance of the system is further analyzed. Through experimental simulation, it is proved that the system has better resistance to attacks and lower bit error rates.

Performance Study of MIMO-OSTBC Parallel Relay FSO System Based on GFDM

Performance Study of MIMO-OSTBC Parallel Relay FSO System Based on GFDM

Multi-Hop Airborne FSO Systems With Relay Selection Over Outdated Log-Normal Turbulence Channels

Multi-Hop Airborne FSO Systems With Relay Selection Over Outdated Log-Normal Turbulence Channels

Free space optical communication system: a review of practical constraints, applications, and challenges

Abstract FSO (free space optical) communication holds emanated position in the role of propitious innovation with exorbitant-speed using the data transmission mechanism without the wire, propounding an accomplishable explication to the surging need for bandwidth in communication networks. This research paper probes into the improvements and obstacles in FSO communication systems, pursuing to anticipate a compendious encapsulation of the state-of-the-art establishment in this discipline. The evaluation incorporates a meticulous inspection of vital constituents such as laser sources, modulators, and receivers, elucidating their contribution to accomplishing coherent data transfer. The scrutinizing also investigates innumerable atmospheric circumstances affecting FSO links, including weather conditions and turbulence, and puts forward ingenious approaches to alleviate their repercussion on communication performance. Furthermore, the paper explores the homogenization of ultra-modern signal processing techniques to amplify the credibility and robustness of FSO systems, corroborating seamless communication even in challenging environments. Moreover, the research inquiries into the neoteric experimental framework and real-world execution of FSO communication, shedding light on heuristic contemplation, and substantiating theoretical unearthing. The conclusion of this research shells out treasures perception of the ongoing attempt to optimize FSO communication for variegated applications, including, inter-satellite communication, high-speed internet access, and last-mile connectivity. As FSO perpetuates progress, this paper suffices as a recent and inclusive resource for researchers, engineers, and policymakers maneuvering the edges of optical communication technologies.

On the Capacity of Decode-and-Forward FSO System With Single- and Dual-Hop RF Link

On the Capacity of Decode-and-Forward FSO System With Single- and Dual-Hop RF Link

Optical Beam Steering in FSO Systems Supported by Computer Vision

Optical Beam Steering in FSO Systems Supported by Computer Vision

Analysis of a Real-Time FSO System Utilizing Xia and SRRC Pulses in Multi-Band Carrier-Less Amplitude and Phase Modulation

Analysis of a Real-Time FSO System Utilizing Xia and SRRC Pulses in Multi-Band Carrier-Less Amplitude and Phase Modulation

On the Impact and Mitigation of Turbulence in Fiber-Coupled FSO Systems

On the Impact and Mitigation of Turbulence in Fiber-Coupled FSO Systems

Differential Chaos Shift Keying for FSO Systems: A Novel Approach Under Turbulence and Boresight Pointing Errors

Differential Chaos Shift Keying for FSO Systems: A Novel Approach Under Turbulence and Boresight Pointing Errors

Multi-Layer Airborne FSO Systems: Performance Analysis and Optimization

Multi-Layer Airborne FSO Systems: Performance Analysis and Optimization