Adaptive Modulation and Coding for Free-Space Optical Channels

Djordjević, Ivan B.

doi:10.1364/jocn.2.000221

Cited by 132 publications

(66 citation statements)

References 11 publications

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“…An interesting extension of this work would be to investigate how these bounds can be approached practically, by using adaptive modulation/coding at a target error/outage probability e.g., as in [40], [46]. Another interesting extension is to investigate the capacity of parallel IM-DD channels with…”

Section: Discussionmentioning

confidence: 99%

“…This can be an RF or an optical channel. In a hybrid RF/optical system, CSIT can be obtained by sending a pilot signal which is used to form a channel estimate at the receiver, which is in turn fed back to the transmitter through an RF feedback channel [40]. In a full-duplex OWC system, CSIT can be estimated directly at the transmitter due to channel reciprocity, by sending a pilot signal from the receiver to the transmitter [18].…”

Section: Constraintmentioning

confidence: 99%

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Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

Chaaban

Rezki

Alouini

2016

IEEE Trans. Commun.

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Section: Discussionmentioning

confidence: 99%

Section: Constraintmentioning

confidence: 99%

Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

Chaaban

Rezki

Alouini

2016

IEEE Trans. Commun.

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“…Generally, a gamma-gamma (GG) distribution is used to model the PDF of the intensity fluctuation as following [28]:…”

Section: Atmospheric Turbulence Induced Fadingmentioning

confidence: 99%

Free Space Optic and mmWave Communications: Technologies, Challenges and Applications

Ismail

Leitgeb

Plank

2016

IEICE Trans. Commun.

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SUMMARY Increasing demand in data-traffic has been addressed over the last few years. It is expected that the data-traffic will present the significant part of the total backbone traffic. Accordingly, much more transmission systems will be required to support this growth. A free space optic (FSO) communication is the greatest promising technology supporting high-speed and high-capacity transport networks. It can support multi Gbit/s for few kilometers transmission distance. The benefits of an FSO system are widespread, low cost, flexibility, immunity to electromagnetic field, fast deployment, security, etc. However, it suffers from some drawbacks, which limit the deployment of FSO links. The main drawback in FSO is the degradation in the signal quality because of atmospheric channel impairments. In addition, it is high sensitive for illumination noise coming from external sources such as sun and lighting systems. It is more benefit that FSO and mmWave are operating as a complementary solution that is known as hybrid FSO/mmWave links. Whereas the mmWave is susceptible to heavy rain conditions and oxygen absorption, while fog has no particular effect. This paper will help to better understand the FSO and mmWave technologies and applications operating under various atmospheric conditions. Furthermore, in order to improve the system performance and availability, several modulation schemes will be discussed. In addition to, the hybrid FSO/mmWave with different diversity combining techniques are presented.

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“…The major effects due to the random fluctuations of the atmospheric turbulence are (i) optical scattering and observation (characterized by atmospheric attenuation); (ii) random optical power fluctuation (characterized by scintillation index); (iii) beam wandering, i.e., beam surface global (temporal) tilt due to beam centroid displacement on the detector plane (characterized by effective scintillation index); and (iv) wavefront distortions, i.e., beam surface (spatial) local tilt (characterized by the Zernike polynomials) [10][11][12]. The conventional data coding and/or modulation techniques can be used to equalize/compromise the first two effects with respect to weather conditions at a given instant of time [13,14]. The third and fourth effects cannot be compromised without incorporating the adaptive optics elements [15,16].…”

Section: Introductionmentioning

confidence: 99%

“…To ensure an uninterrupted data flow, auto-alignment transmitter and receiver modules are necessary [12,17,18]. The data loss due to weak scintillation effects can be recovered using various data coding techniques developed for wire-and fiber-based communication systems [13,14]. In contest, beam wandering and deep signal fading (wavefront distortions) represent unique and significantly more challenging problems, which cannot be resolved using conventional data coding techniques, and a major incentive for the incorporation of adaptive optics technology (beam wandering mitigation and wavefront corrections) into the FSOC architecture is an active prevention of long-term data loss [12,15,16].…”

Section: Introductionmentioning

confidence: 99%

Intensity feedback-based beam wandering mitigation in free-space optical communication using neural control technique

Raj¹,

Selvi

Durai

et al. 2014

J Wireless Com Network

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Over the last two decades, free-space optical communication (FSOC) has become more and more interesting as an adjacent and/or alternative to radio frequency (RF) and optical fiber communications. The optical wave propagation in the FSOC channel is severely affected by atmospheric parameters, and it leads to the degradation of the data transmission quality and reliability. Among the various atmospheric effects, the beam wandering is the main cause of major power loss and cannot be solved without the incorporation of the beam centroid stabilization system. Therefore, designing a suitable opto-electronic assembly with a beam wandering mitigation system becomes significant to improve the performance of the FSOC system. A FSOC experimental setup is developed for the link range of 0.5 km in the college campus. A neural controller is designed for beam wandering mitigation. The neural controller processed the beam pointing (beam location) information obtained from an opto-electronic position detector (OPD) and then generated the necessary control outputs to the fast steering mirror (FSM) to steer the beam in the counter-direction to mitigate the beam wander at the receiver station. New design approach and architecture development for the implementation of the designed neural controller in the field-programmable gate array (FPGA) to mitigate the beam wandering are presented. The investigations on the performance of the neural controller in aiming a laser beam to be at a particular point on the detector plane are tested under dynamic disturbances generated at the transmitter in addition to the atmospheric effects through which the maximum correction capability of the developed neural controller is examined. Evidence of the suitability and the effectiveness of the proposed neural controller is evaluated in terms of beam centroid displacement, power spectral density (PSD), radial displacement on a 2D plane, effective scintillation index (ESI), Q-factor, and bit error rate (BER). The beam wandering range of −0.13 to +0.16 mm, maximum of 55 dB disturbance band attenuation with a frequency range of 0 Hz through 2 kHz, ESI of 0 to 0.15, Q-factor of 6, and BER of 6.45 × 10 −9 are achieved due to the incorporation of the developed neural controller in different real-world environmental conditions.

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Adaptive Modulation and Coding for Free-Space Optical Channels

Cited by 132 publications

References 11 publications

Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

Free Space Optic and mmWave Communications: Technologies, Challenges and Applications

Intensity feedback-based beam wandering mitigation in free-space optical communication using neural control technique

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