Studies of pointing, acquisition, and tracking of agile optical wireless transceivers for free-space optical communication networks

Ho, Tzung-Hsien; Trisno, Sugianto; Smolyaninov, Igor I.; Milner, Stuart D.; Davis, Christophér C.

doi:10.1117/12.511373

Cited by 31 publications

(18 citation statements)

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“…Since the beams under study enter the lens at an angle and intersect the entire lens area, the full geometrical effects of the lens are considered, resulting in a phase retardation given by (3) where z o is the maximum thickness of the lens, n is the refractive index, R 1 and R 2 are the curvatures of the first and second surface, respectively, and ρ 2 = x 2 + y 2 . To simplify calculations and reflect typical experimental conditions, the lens is assumed biconvex (R 1 = R 2 = R) with a refractive index of 1.5, under which conditions the focal length f ≈ R. The field just after the lens is then given by (4) To propagate this field to the fiber plane (x′, y′), a convolution integral is calculated using the spatial impulse response. The resulting equation for the field at a distance f behind the lens is given by (5) where the integral is over the entire area of the lens and is repeated for each point (x′, y′) in the fiber plane.…”

Section: Plane Wave Analysismentioning

confidence: 99%

“…FSO is being seriously investigated as a means for establishing high-bandwidth links for a variety of applications, including inter-satellite communication, airborne internet, disaster recovery communications, and battlefield communication [1][2][3][4] . The high bandwidth available with FSO makes it an attractive option for such applications since a permanent communication link is not required to move large amounts of data.…”

Section: Introductionmentioning

confidence: 99%

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Mitigating angular misalignment from atmospheric effects in FSO links

2007

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Accuracy of alignment is a key factor for successfully establishing and maintaining connections in networks of freespace optical links, and is particularly critical when one or both of the transceivers are moving. Scintillation and other atmospheric effects create beam deflections that further complicate the alignment process by creating rays that enter the receiver at an angle to the optical axis. This paper theoretically studies the effective angular misalignment that can be caused by such deflections and mitigation methods for a traditional free-space optical link. The theory uses Gaussian beam propagation and system theory to determine the optical power distribution at the receiver lens and the position of the beam at the lens focal point. Coordinate transformation and overlap integrals are used to assist in calculating the amount of power collected by the lens and incident on the collecting core of the fiber. The use of a fiber bundle at the focal plane of the lens is investigated as a possible method for reducing the receiver sensitivity to misalignment. The simulation results show that some reduction in misalignment sensitivity within some practical system design limits.

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Section: Plane Wave Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mitigating angular misalignment from atmospheric effects in FSO links

2007

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“…Therefore, an automatic beam pointing, acquisition and tracking (PAT) mechanism with associated protocol and software are required at each transceiver and each mirror. Such systems have been proposed and studied in the literature, see for example [9], [10]. In our model these errors do not affect link reliability, only link outage probability which in turn affects maximum link distance.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Free Space Optical Wireless Network for Cellular Backhauling

Παππάς

Angelakis

et al. 2015

IEEE J. Select. Areas Commun.

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Abstract-With the densification of nodes in cellular networks, free space optic (FSO) connections are becoming an appealing low cost and high rate alternative to copper and fiber backhaul solutions for wireless communication systems. To ensure a reliable cellular backhaul, provisions for redundant, disjoint paths between the nodes must be made in the design phase. This paper aims at finding a cost-effective solution to upgrade the cellular backhaul with pre-deployed optical fibers using FSO links and mirror components. Since the quality of the FSO links depends on several factors, such as transmission distance, power, and weather conditions, we adopt an elaborate formulation to calculate link reliability. We present a novel integer linear programming model to approach optimal FSO backhaul design, guaranteeing K-disjoint paths connecting each node pair. Next, we derive a column generation method to a path-oriented mathematical formulation. Applying the method in a sequential manner enables high computational scalability. We use realistic scenarios to demonstrate our approaches efficiently, provide optimal or near-optimal solutions, and thereby allow for accurately dealing with the trade-off between cost and reliability.

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“…3) Complexity associated with physical topology implementation through beam redirection: Physical beam redirection is achieved through pointing, acquisition and tracking (PAT) [10,11]. For purposes of simulation and modeling, we have abstracted this functionality assuming a conservative estimate of 2 seconds for physical implementation of the new network.…”

Section: Introductionmentioning

confidence: 99%

Optimizing performance of hybrid FSO/RF networks in realistic dynamic scenarios

et al. 2005

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Hybrid Free Space Optical (FSO) and Radio Frequency (RF) networks promise highly available wireless broadband connectivity and quality of service (QoS), particularly suitable for emerging network applications involving extremely high data rate transmissions such as high quality video-on-demand and real-time surveillance. FSO links are prone to atmospheric obscuration (fog, clouds, snow, etc) and are difficult to align over long distances due the use of narrow laser beams and the effect of atmospheric turbulence. These problems can be mitigated by using adjunct directional RF links, which provide backup connectivity. In this paper, methodologies for modeling and simulation of hybrid FSO/RF networks are described. Individual link propagation models are derived using scattering theory, as well as experimental measurements. MATLAB is used to generate realistic atmospheric obscuration scenarios, including moving cloud layers at different altitudes. These scenarios are then imported into a network simulator (OPNET) to emulate mobile hybrid FSO/RF networks. This framework allows accurate analysis of the effects of node mobility, atmospheric obscuration and traffic demands on network performance, and precise evaluation of topology reconfiguration algorithms as they react to dynamic changes in the network. Results show how topology reconfiguration algorithms, together with enhancements to TCP/IP protocols which reduce the network response time, enable the network to rapidly detect and act upon link state changes in highly dynamic environments, ensuring optimized network performance and availability.

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Studies of pointing, acquisition, and tracking of agile optical wireless transceivers for free-space optical communication networks

Cited by 31 publications

References 0 publications

Mitigating angular misalignment from atmospheric effects in FSO links

Mitigating angular misalignment from atmospheric effects in FSO links

Optimization of Free Space Optical Wireless Network for Cellular Backhauling

Optimizing performance of hybrid FSO/RF networks in realistic dynamic scenarios

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