Free Space Optics, Channel Models and Hybrid Modulation Schemes: A Review

Magidi, S.; Jabeena, A.

doi:10.1007/s11277-021-08380-9

Cited by 21 publications

(9 citation statements)

References 93 publications

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“…According to Equation (5), we obtain: (7) where denotes average system synthesis. For a coherent detection system, the scattered particle noise caused by the local oscillation light is much larger than other noises, and it can be assumed that the noise at the receiver side mainly originates from the local oscillation light [25]:…”

Section: Theoretical Research 21 Coherent Detection Principlementioning

confidence: 99%

Effect of Wavefront Distortion on the Performance of Coherent Detection Systems: Theoretical Analysis and Experimental Research

Yang

Xing

et al. 2023

Photonics

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Atmospheric turbulence causes signal beam wavefront distortion at the receiving end of a coherent detection system, which decreases the system mixing efficiency. Based on the coherent detection theory, this study establishes a mathematical model of wavefront distortion with mixing efficiency and mixing gain. It also analyzes the improvement limits of wavefront correction on mixing efficiency and mixing gain under different atmospheric turbulence intensities and experimentally measures them. Simulation results show that the mixing efficiency can be improved to 51%, 55%, and 60% after correcting for tilt, defocus, and astigmatism terms, respectively, when turbulence intensity D/r0 is 2. The mixing gain with homodyne detection is 3 dB higher than heterodyne detection. Meanwhile, the wavefront correction orders required for optimal mixing efficiency are higher than the heterodyne correction order. In the experiment, Haso4 NIR + DM 40 was used, and the turbulence intensity D/r0 was 2. After the closed-loop control algorithm corrects the tilt, defocus, and astigmatism terms, the indoor experimental results showed that the mixing efficiency is improved to 36%, 47%, and 62%, respectively. The outdoor experimental results showed that the mixing efficiency improved to 36%, 51%, and 68%, respectively.

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Section: Theoretical Research 21 Coherent Detection Principlementioning

confidence: 99%

Effect of Wavefront Distortion on the Performance of Coherent Detection Systems: Theoretical Analysis and Experimental Research

Yang

Xing

et al. 2023

Photonics

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“…Stronger is the IR and UV, stronger will be the intensity of signal [22][23][24][25][26][27]. Some other related work similar to the mentioned above has been done by many authors in their manuscripts [13][14][15][16][17][18][19][20][21]. Working in the field of FSO is thus a very appealing option.…”

Section: Work Done In India and Abroadmentioning

confidence: 99%

Performance Analysis of Multi User Optical Wireless Network (IR, or UV light for signal carrying) under Different Environmental Conditions

2022

Global NEST: The International Journal

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<p>The field of optics is flourishing day by day on account of the wide usage of the internet and its associated technologies. Free Space Optics (FSO) is a data transmission technique that employs light propagation to send data. This technology is effective in those circumstances where fiber optic cables cannot be deployed. This paper provides a model and simulation of the Fiber Bragg Grating (FBG) based FSO network under different environmental conditions, such as modulation types and data rates. Also, investigation of the impact of Multiple Access Interference (MAI) on FSO under design parameters has been done. The designed system performance is analyzed under the multiuser optical wireless network by changing data rates and modulation types. The proposed model's security is achieved through the use of the FBG encoder/decoder and the FSO channel for transmission. It has been inferred that the CRZ modulation type provides the best BER and Q factor compared to other formats, and a data rate as high as 1Gbps can be achieved using the CRZ modulation format. It has been noticed that as the number of users grows, the BER value begins to deteriorate.</p>

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“…Notably, the mobile FSOC link must be maintained by the beam-tracking mechanism, and the pointing error comes from its photoelectric detector noise and platform vibration residual noise which cause the propagation characteristics and irradiance distribution to be different from previous research [16][17][18]. Hence, the pointing error of the beam-tracking mechanism inevitably influences the irradiance distribution, which is one of the most critical characteristics of an HG beam.…”

Section: Introductionmentioning

confidence: 99%

Propagation Characteristics of Hermite–Gaussian Beam under Pointing Error in Free Space

et al. 2022

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Hermite–Gaussian (HG) beams have significant potential to improve the capacity of free-space optical communication (FSOC). The influence of pointing error on the propagation characteristics of an HG beam cannot be ignored in the FSOC system. Although the average irradiance of the HG beam under a small pointing error from the FSOC tracking mechanism has been investigated through Taylor series approximation, here, we propose that the average irradiance of the HG beam under an arbitrary magnitude pointing error can be deduced through a statistical averaging method. We firstly found that the average irradiance profile of an HG beam finally changes into an approximately Gaussian shape with the increase in pointing error and propagation distance and a larger beam waist at the transmitter could mitigate the profile change. The correlation coefficient between deduced theoretical expression and Monte Carlo simulation reaches 0.999. Additionally, the effective spot size, location of the local extreme value, average received power and signal-to-noise ratio (SNR) loss for an HG beam under pointing error were theoretically deduced and analyzed for the first time. We found that the effective spot size of the higher-order HG beam experiences less broadening under the pointing error than that of the lower-order HG beam. The fundamental theoretical expressions of average irradiance for an HG beam under pointing error have provided effective guidance for analyzing the propagation characteristics and link performance.

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Free Space Optics, Channel Models and Hybrid Modulation Schemes: A Review

Cited by 21 publications

References 93 publications

Effect of Wavefront Distortion on the Performance of Coherent Detection Systems: Theoretical Analysis and Experimental Research

Effect of Wavefront Distortion on the Performance of Coherent Detection Systems: Theoretical Analysis and Experimental Research

Performance Analysis of Multi User Optical Wireless Network (IR, or UV light for signal carrying) under Different Environmental Conditions

Propagation Characteristics of Hermite–Gaussian Beam under Pointing Error in Free Space

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