Bit Error Rate Analysis for Modulating Retro-Reflector Free Space Optical Communications With Adaptive Threshold Over Correlated Gamma Gamma Fading Channels

Li, Xiaoyan; Zhao, Xiaohui; Zhang, Peng

doi:10.1109/lcomm.2019.2943868

Cited by 18 publications

(12 citation statements)

References 12 publications

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“…The retro-reflected turbulence fading coefficient thus can be described as the product of two correlated GG RVs. Although an expression for the joint PDF of the product of two correlated GG RVs was readily derived in [21], it involves complicated infinite summation terms. Nevertheless, it has been verified by experiments in [15] that a single GG distribution could provide a well approximation to the histogram data of the retro-reflected link.…”

Section: ) Log-normal Turbulence Modelmentioning

confidence: 99%

“…From the theoretical aspect, the statistical channel models for the retro-reflected terrestrial FSO links have only been investigated by a limited number of research works [15]- [23]. In fact, all previous works merely focused on characterizing the effect of atmospheric turbulence [15]- [21], and the misalignments in the forward link (i.e. from the transmitter to the MRR) [22], [23], without considering the misalignments in the retro-reflected link when the MRR is installed on a hovering drone.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Channel Statistics of Drone-to-Ground Retro-Reflected FSO Links With Fine-Tracking Systems

Trinh¹,

Carrasco‐Casado

Okura

et al. 2021

IEEE Access

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The utilization of drones as flying base stations (BSs) in the sixth-generation (6G) cellular networks has attracted much attention recently. In this context, free-space optical (FSO) systems could be deployed to provide high-capacity fronthaul/backhaul links between drones and ground BSs. Particularly, a drone-to-ground FSO communication link can be established by equipping the drone with a modulating retro-reflector (MRR) to modulate the incoming optical beam and reflect the modulated beam back along the same path. This helps to alleviate stringent pointing requirements from the drone while satisfying the limited size, weight, and power (SWaP) consumption requirements. Nevertheless, the underlying physical channel effects of this aerial retro-reflected FSO system have never been experimentally explored in the literature. In this paper, we report, for the first time, the experimental channel statistics of a drone-to-ground retroreflected FSO link, offering practical insights into the angle-of-arrival (AoA) fluctuations at the receiver, the channel coherence time, the probability of fade, the level crossing rate, the average fade duration, and the time-frequency channel characteristics. Our results are expected to serve as practical sources of reference for the theoretical performance analyses and engineering designs of drone-based retro-reflected FSO systems.INDEX TERMS Free-space optics (FSO), unmanned aerial vehicles (UAVs), aerial fronthaul/backhaul links, drone hovering, fine-tracking systems.

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Section: ) Log-normal Turbulence Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Channel Statistics of Drone-to-Ground Retro-Reflected FSO Links With Fine-Tracking Systems

Trinh¹,

Carrasco‐Casado

Okura

et al. 2021

IEEE Access

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“…Nevertheless, it only studies the case of weak turbulence and does not consider the aperture averaging effect. The performance of an MMR system with adaptive threshold over correlated Gamma-Gamma model has been investigated in [18]. The adaptive threshold was constructed by using the training data received from the detector, not by solving the equation.…”

Section: Introductionmentioning

confidence: 99%

Average Ber Analysis of Free-Space Optical Communications With Adaptive Threshold Technique Over Exponentiated Weibull Distribution

Zhang¹,

Wang²,

Huang³

et al. 2021

PIER Letters

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Average bit error rate (BER) performance of on-off keying (OOK) modulation in a free space optical (FSO) system, which is based on adaptive threshold technique under atmospheric turbulence described by exponentiated Weibull (EW) distribution, is studied and compared with that of using fixed threshold technique. In order to solve the adaptive threshold, the equation is simplified by using the generalized Gauss-Laguerre polynomial function, which significantly improves the operational efficiency. The simulation results show that the adaptive threshold varies with the average transmitted power under different noise variances, receiving aperture sizes and turbulence conditions. Compared with the fixed threshold technique, the adaptive threshold technique can greatly improve the BER performance of FSO communication system.

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“…In the MRR-based topology, complexity and tracking equipment are transferred from the UAV node to the GS. Even though MRRbased optical wireless communications have been well studied in the context of underwater optical wireless communications [22], this subject is restricted to few works in the context of UAV-based FSO communications [23]- [30]. In [23], [24], the authors design and implement a real-time localization and 1 An MRR consists of an optical retroreflector with a modulator to first modulate the incoming optical signal and then reflect it toward the transmitter.…”

mentioning

confidence: 99%

“…Impacts of shape and size of MRR cell along with turbulence condition on the beam spot are investigated in [28] by the theoretical analysis and wave-optics simulation. In [29], [30], the effects of the parameters such as atmospheric turbulence conditions, link length, Rx's aperture diameter and the average signal-to-noise ratio (SNR) are studied on the performance of MRR-based FSO links. However, the results of [25]- [30] are obtained by neglecting the effect of geometrical pointing errors which are only valid when the GS node perfectly pointed optical beam towards the aperture of MMR mounted on UAV.…”

mentioning

confidence: 99%

Modulating Retroreflector Based Free Space Optical Link for UAV-to-Ground Communications

Dabiri¹,

Rezaee²,

Mohammadi³

et al. 2022

Preprint

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Weight reduction and low power consumption are key requirements in the next generation of unmanned aerial vehicle (UAV) networks. Employing modulating retro-reflector (MRR)-based free space optical (FSO) technology is an innovative technique for UAV-to-ground communication in order to reduce the payload weight and power consumption of UAVs which leads to increased maneuverability and flight time of UAV. In this paper, we consider an MRR-based FSO system for UAVto-ground communication. We will show that the performance of the considered system is very sensitive to tracking errors. Therefore, to assess the benefits of MRR-based UAV deployment for FSO communications, the MRR-based UAV FSO channel is characterized by taking into account tracking system errors along with UAV's orientation fluctuations, link length, UAV's height, optical beam divergence angle, effective area of MRR, atmospheric turbulence and optical channel loss in the doublepass channels. To enable effective performance analysis, tractable and closed-form expressions are derived for probability density function of end-to-end signal to noise ratio, outage probability and bit error rate of the considered system under both weak-tomoderate and moderate-to-strong atmospheric turbulence conditions. The accuracy of the analytical expressions is verified by extensive simulations. Analytical results are then used to study the relationship between the optimal system design and tracking system errors.Index Terms-Angle of arrival (AoA) fluctuations, FSO communications, UAV, modulating retro-reflector (MRR). I. INTRODUCTIONU NMANNED aerial vehicles (UAVs) have been introduced to overcome many of the shortcomings of the current terrestrial infrastructure by operating as aerial communication nodes and providing robust line-of-sight (LoS) connectivity to ground devices [1], [2]. UAVs deployed as flying communication nodes using radio frequency (RF) will interfere with ground devices, hence degrading the performance of the ground network. Employing UAVs equipped with free space optical (FSO) technology is a promising method for future ultra dense wireless networks [3]. FSO communication systems use very small beam divergence which is physically inaccessible to RF technologies, thus, making FSO links extremely secure. Moreover, FSO system is much faster, easier to deploy, more compact, and cheaper than RF [4]- [6]. However, vulnerability to signal blockage is one of the fundamental limitations of FSO links that essentially confines the receiver to be placed within the line-of-sight (LoS) of the transmitter. A potential application of UAV-assisted FSO systems is in dense cities with tall buildings where a UAV can act as an aerial relay to connect source and destination nodes where the LoS between ground optical nodes is interrupted by tall buildings [7], [8].

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Bit Error Rate Analysis for Modulating Retro-Reflector Free Space Optical Communications With Adaptive Threshold Over Correlated Gamma Gamma Fading Channels

Cited by 18 publications

References 12 publications

Experimental Channel Statistics of Drone-to-Ground Retro-Reflected FSO Links With Fine-Tracking Systems

Experimental Channel Statistics of Drone-to-Ground Retro-Reflected FSO Links With Fine-Tracking Systems

Average Ber Analysis of Free-Space Optical Communications With Adaptive Threshold Technique Over Exponentiated Weibull Distribution

Modulating Retroreflector Based Free Space Optical Link for UAV-to-Ground Communications

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