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Retransmission management for RWA using the suitability index in OBS networks

JOURNAL OF OPTICAL NETWORKING 2008年第5期7卷 410-425页

作者： Hirota, Yusuke Tode, Hideki Murakami, Koso Osaka Univ Grad Sch Informat Sci & Technol Dept Informat Networking Suita Osaka 5650871 Japan

We focus on the collision avoidance problem in distributed optical burst switching (OBS) networks. Our proposal involves cooperation between the routing and the wavelength assignment tasks. The main idea is to classify each wavelength at an output link of a node as suited either to sending or to relaying data bursts. Furthermore, burst retransmission management is important to realize OBS networks. We propose the cooperation method considering retransmission. Simulation results show that the proposed method can reduce the burst loss probability, particularly for long-distance transmissions. As a result, unfairness in the treatment of short and long hop bursts can be alleviated. (C) 2008 Optical Society of America.

关键词： assignment algorithms Optical networks Optical switching devices Packet switching Time division multiplexing Wavelength assignment

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State space approach to single molecule localization in fluorescence microscopy

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BIOMEDICAL OPTICS EXPRESS 2017年第3期8卷 1332-1355页

作者： Vahid, Milad R. Chao, Jerry Kim, Dongyoung Ward, E. Sally Ober, Raimund J. Texas A&M Univ Dept Biomed Engn College Stn TX 77843 USA Texas A&M Hlth Sci Ctr Dept Mol & Cellular Med College Stn TX 77843 USA Texas A&M Hlth Sci Ctr Dept Microbial Pathogenesis & Immunol College Stn TX 77843 USA

Single molecule super-resolution microscopy enables imaging at sub-diffraction-limit resolution by producing images of subsets of stochastically photoactivated fluorophores over a sequence of frames. In each frame of the sequence, the fluorophores are accurately localized, and the estimated locations are used to construct a high-resolution image of the cellular structures labeled by the fluorophores. Many methods have been developed for localizing fluorophores from the images. The majority of these methods comprise two separate steps: detection and estimation. In the detection step, fluorophores are identified. In the estimation step, the locations of the identified fluorophores are estimated through an iterative approach. Here, we propose a non-iterative state space-based localization method which combines the detection and estimation steps. We demonstrate that the estimated locations obtained from the proposed method can be used as initial conditions in an estimation routine to potentially obtain improved location estimates. The proposed method models the given image as the frequency response of a multi-order system obtained with a balanced state space realization algorithm based on the singular value decomposition of a Hankel matrix. The locations of the poles of the resulting system determine the peak locations in the frequency domain, and the locations of the most significant peaks correspond to the single molecule locations in the original image. The performance of the method is validated using both simulated and experimental data. (C) 2017 Optical Society of America.

关键词： assignment algorithms CCD cameras Fluorescence microscopy Fourier transforms Photon counting Super resolution microscopy

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Multicasting for all-optical multifiber networks

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JOURNAL OF OPTICAL NETWORKING 2007年第2期6卷 219-238页

作者： Koksal, Fatih Ersoy, Cem Bogazici Univ Dept Comp Engn NETLAB TR-34342 Istanbul Turkey

All-optical wavelength-routed WDM WANs can support the high bandwidth and the long session duration requirements of the application scenarios such as interactive distance learning or on-line diagnosis of patients simultaneously in different hospitals. However, multifiber and limited sparse light splitting and wavelength conversion capabilities of switches result in a difficult optimization problem. We attack this problem using a layered graph model. The problem is defined as a k-edge-disjoint degree-constrained Steiner tree problem for routing and fiber and wavelength assignment of k multicasts. A mixed integer linear programming formulation for the problem is given, and a solution using CPLEX is provided. However, the complexity of the problem grows quickly with respect to the number of edges in the layered graph, which depends on the number of nodes, fibers, wavelengths, and multicast sessions. Hence, we propose two heuristics layered all-optical multicast algorithm [( LAMA) and conservative fiber and wavelength assignment (C-FWA)] to compare with CPLEX, existing work, and unicasting. Extensive computational experiments show that LAMA's performance is very close to CPLEX, and it is significantly better than existing work and C-FWA for nearly all metrics, since LAMA jointly optimizes routing and fiber-wavelength assignment phases compared with the other candidates, which attack the problem by decomposing two phases. Experiments also show that important metrics (e. g., session and group blocking probability, transmitter wavelength, and fiber conversion resources) are adversely affected by the separation of two phases. Finally, the fiber- wavelength assignment strategy of C-FWA (Ex-Fit) uses wavelength and fiber conversion resources more effectively than the First Fit. (c) 2007 Optical Society of America.

关键词： All optical networks assignment algorithms Network topology Optical networks Wavelength assignment Wavelength conversion

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Service blockage on the downlink in large-scale satellite optical networks: a multi-downlink scheduling for routing selection

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OPTICS EXPRESS 2024年第10期32卷 17499-17513页

作者： Wang, Hua Liu, Yuhang Yang, Zhenghao Yi, Longteng Zhao, Yongli Wang, Long Hang, Jiez Nanjing Tech Univ Sch Comp & Informat Engn Nanjing 210037 Jiangsu Peoples R China Beijing Univ Posts & Telecommun State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China China Acad Space Technol CAST Beijing 100876 Peoples R China Chinese Acad Sci Innovat Acad Microsatellites Shanghai 100876 Peoples R China

Over years of space laser communication technology advances, satellite optical networks (SONs) have emerged as a pivotal component in 6 G networks. Satellite services are transmitted from the global view, undergoing transmission through SONs, and being downloaded to the targeted areas. However, the transmission capacity of satellites passing through the areas where users are concentrated may be insufficient to download services transmitted worldwide. This problem exists in various kinds of satellite networks and may cause a large amount of service congestion. In this paper, we propose a multi-downlink delivery routing selection (MDD-RS) strategy to study the total utilization of transmission capacity of SONs. We construct an integer linear programming (ILP) model to establish an optimal case study for minimal network capacity occupation. Also, we design an online option, MDD-RS heuristic algorithm, dynamically calculating path routes, considering bandwidth allocation and resource constraints. A comparative analysis against the conventional single-downlink scheme reveals superior performance of the MDD-RS heuristic algorithm, with a reduction in blocking probability of 0.129 and an improvement in bandwidth utilization of 0.032.

关键词： assignment algorithms Laser communications Machine learning Network topology Optical communications Optical networks

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Flexible low-latency metro-access converged network architecture based on optical time slice switching

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JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING 2019年第12期11卷 624-635页

作者： Li, Jialong Hua, Nan Zhong, Zhizhen Yu, Yufang Zheng, Xiaoping Zhou, Bingkun Tsinghua Univ Beijing Natl Res Ctr Informat Sci & Technol BNRis Dept Elect Engn Beijing 100084 Peoples R China

The "pay-as-you-grow" cloud computing model has become popular for today's enterprises. Cloud computing not only frees end users from complex operations, but also allows higher resource utilization, lower investment, and increased energy efficiency. However, with some emerging technologies, cloud computing is unable to meet the required latency level, especially for delay-sensitive services such as 5G communications, live streaming, and online gaming. In this context, edge computing is regarded as a promising technology that can provide low-latency connections in the near future. Unlike cloud computing, which provides service in a centralized mode, edge computing deploys micro data centers (MDCs) at the edge of the network to provide rapid-response service. However, due to the limited computing and storage capacity of a single MDC, a user may not be able to access the resources from the closest MDC during peak traffic periods. Under such circumstances, the user is served through another MDC or a remote cloud data center. The data are processed in an optical line terminal and then transmitted via the metro network, which significantly increases the latency. In this study, we introduce a flexible low-latency metro-access converged network architecture based on optical time slice switching (OTSS) to address the latency problem. By leveraging the transparent connections of the OTSS in this novel architecture, data can be transmitted through the MDCs without requiring extra processing time. The simulation results demonstrate that our proposed architecture can provide lower-latency connections under a range of conditions, with a negligible decrease in network throughput, compared with an existing representative architecture. Additionally, we conducted experiments to validate the feasibility of our approach. (C) 2019 Optical Society of America

关键词： assignment algorithms Optical access networks Optical buffers Optical network architecture Optical networks Packet switching

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Consolidation strategies of provisioning-oriented optical networks

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JOURNAL OF OPTICAL NETWORKING 2006年第6期5卷 445-462页

作者： Karasz, Tamas Budapest Univ Technol & Econ Dept Telecommun H-1117 Budapest Hungary

Fast provisioning capabilities enabled by signaling intelligence and automated switching flexibility are becoming fundamental features of next-generation networks based on optical transport. In recent years numerous research and development projects, standardization activities, and a large number of publications have been devoted to fast-provisioning-enabled optical networks. However, in the related research activities less attention has been paid to network state evolution during the provisioning process. Our main scope is, based on a three-phase network development life cycle, to define different consolidation strategies to improve the performance of provisioning-oriented optical networks. The proposal is motivated by the inherent lack of capacity efficiency of optical channel provisioning processes. (C) 2006 Optical Society of America.

关键词： assignment algorithms Genetic algorithms Network topology Optical networks Wavelength assignment Wavelength conversion

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Effect of freeform surfaces on the volume and performance of unobscured three mirror imagers in comparison with off-axis rotationally symmetric polynomials

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OPTICS EXPRESS 2019年第15期27卷 21751-21766页

作者： Schiesser, Eric M. Bauer, Aaron Rolland, Jannick P. Univ Rochester Inst Opt 275 Hutchison Rd Rochester NY 14627 USA

The invention of new design techniques for unobscured reflective systems using freeform surfaces has expanded the optical design space for these system types. We illustrate how the use of freeform surfaces can expand the design space of the Three Mirror Compact design type to allow both better performance at a given system volume and smaller volumes for a given performance target. By evolving designs using conventional off-axis asphere type surfaces to ever smaller volumes and then converting these off-axis asphere descriptions to centered Zernike descriptions, we show that the wavefront error improves by up to 69% in this case by allowing the surfaces to break rotational symmetry. In addition. we show that evolving designs from the same starting point as the off-axis asphere designs but instead using a centered Zernike description can produce a design with a 39% smaller volume in this case while maintaining the same diffraction-limited performance. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： assignment algorithms Diffraction limit Freeform surfaces Optical aberrations Optical design software Optical surfaces

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Spectral and dynamical validity of the rotating-wave approximation in the quantum and semiclassical Rabi models [Invited]

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2024年第8期41卷 C188-C198页

作者： Coleman, H. F. A. Twyeffort, E. K. Univ Southampton Sch Phys & Astron Southampton SO17 1BJ England

Ultrastrong coupling (USC) in the quantum Rabi model, characterized by the breakdown of the rotating-wave approximation (RWA), has emerged as a topic of considerable interest and study. This critical reevaluation of the validity of the RWA concludes that the accepted definition of USC in terms of a fixed ratio of coupling to field frequency is inadequate. Connecting an improved spectral validity criterion with the derivation of the semiclassical limit suggests that the dynamical validity of the quantum RWA should be linked to that of the corresponding semiclassical model. This, however, is not supported by numerical calculations of coherent-state dynamics, which unambiguously demonstrate that spectral validity does not imply dynamical validity and reveal surprisingly complicated dependence on coupling and field amplitude.

关键词： assignment algorithms Cavity quantum electrodynamics Coherent states Fourier transforms Light matter interactions Two level systems

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Layer 1 VPN services in distributed next-generation SONET/SDH networks with inverse multiplexing

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JOURNAL OF OPTICAL NETWORKING 2006年第5期5卷 367-382页

作者： Ghani, N Muthalaly, MV Benhaddou, D Alanqar, W Tennessee Technol Univ Cookeville TN 38505 USA Univ Houston Houston TX USA

Advances in next-generation SONET/SDH along with GMPLS control architectures have enabled many new service provisioning capabilities. In particular, a key services paradigm is the emergent Layer 1 virtual private network (L1 VPN) framework, which allows multiple clients to utilize a common physical infrastructure and provision their own "virtualized" circuit-switched networks. This precludes expensive infrastructure builds and increases resource utilization for carriers. Along these lines, a novel L1 VPN services resource management scheme for next-generation SONET/SDH networks is proposed that fully leverages advanced virtual concatenation and inverse multiplexing features. Additionally, both centralized and distributed GMPLS-based implementations are also tabled to support the proposed L1 VPN services model. Detailed performance analysis results are presented along with avenues for future research. (C) 2006 Optical Society of America.

关键词： assignment algorithms Bismuth Circuit switched networks Multiplexing Optical networks Wavelength assignment

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Service restoration in multi-modal optical transport networks with reinforcement learning

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OPTICS EXPRESS 2021年第3期29卷 3825-3840页

作者： Zhao, Zipiao Zhao, Yongli Li, Yajie Wang, Feng Li, Xinghua Han, Dahai Zhang, Jie Beijing Univ Posts & Telecommun State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China Ningxia Grid Informat & Telecommun Co Yinchuan Ningxia Peoples R China

Optical transport networks (OTNs), while increasingly popular, can be affected in ways that are challenging to restore efficiently. This study investigates the problem of service restoration under OTNs with an optical channel data unit (ODU)-k switching capability (OTN-OSC) environment. An advantage actor-critic-based service restoration (A2CSR) algorithm is presented with the objective of increasing the service restoration rate. In our experimental setup, A2CSR uses the advanced image recognition model MobileNetV2 and an advantage actor-critic reinforcement learning algorithm. Simulation results show that the proposed A2CSR algorithm can achieve better blocking probability and resource utilisation than the benchmark algorithm (first fit (FF)), and the restoration time is within the acceptable range. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： assignment algorithms Image recognition Network optimization Network topology Neural networks Optical networks

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