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1.
  • Abedifar, Vahid, et al. (författare)
  • Routing, Modulation and Spectrum Assignment in Programmable Networks based on Optical White Boxes
  • 2018
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 10:9, s. 723-735
  • Tidskriftsartikel (refereegranskat)abstract
    • Elastic optical networks (EONs) can help overcome the flexibility challenges imposed by emerging heterogeneous and bandwidth-intensive applications. Among the different solutions for flexible optical nodes, optical white box switches implemented by architecture on demand (AoD) have the capability to dynamically adapt their architecture and module configuration to the switching and processing requirements of the network traffic. Such adaptability allows for unprecedented flexibility in balancing the number of required nodal components in the network, spectral resource usage, and length of the established paths. To investigate these trade-offs and achieve cost-efficient network operation, we formulate the routing, modulation, and spectrum assignment (RMSA) problem in AoD-based EONs and propose three RMSA strategies aimed at optimizing a particular combination of these performance indicators. The strategies rely on a newly proposed internal node configuration matrix that models the structure of optical white box nodes in the network, thus facilitating hardware-aware routing of connection demands. The proposed strategies are evaluated in terms of the number of required modules and the related cost, spectral resource usage, and average path length. Extensive simulation results show that the proposed RMSA strategies can achieve remarkable cost savings by requiring fewer switching modules than the benchmarking approaches, at a favorable trade-off with spectrum usage and path length.
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2.
  • Ahmed, Jawwad, et al. (författare)
  • Hybrid Survivability Schemes Achieving High Connection Availability With a Reduced Amount of Backup Resources
  • 2013
  • Ingår i: Journal of Optical Communications and Networking. - : The Optical Society of America. - 1943-0620 .- 1943-0639. ; 5:10, s. A152-A161
  • Tidskriftsartikel (refereegranskat)abstract
    • Maximizing connection availability in WDM networks is critical because even small disruptions can cause huge data losses. However, there is a trade-off between the level of network survivability and the cost related to the backup resources to be provided. The 100% survivability can be achieved by dedicated path protection with multiple pre-reserved protection paths for each provisioned connection, i.e., DPP (1:N). Unfortunately, the blocking probability performance of DPP (1:N) is negatively affected by the large number of pre-reserved backup wavelengths standing-by unutilized. On the other hand, path restoration (PR)-based solutions ensure good blocking performance at the expense of lower connection availability.The work in this paper aims at finding hybrid network survivability strategies that combine the benefits of both techniques (i.e., high availability with low blocking rate). More specifically, the paper focuses on a double link failure scenario and proposes two strategies. The first one, couples dedicated path protection DPP (1:1) with path restoration (referred to as DPP + PR) to minimize the number of dropped connections. The second scheme adds up the concept of backup reprovisioning (BR), referred to as DPP + BR + PR, in order to further increase the connection availability achieved by DPP + PR. Integer Linear Programming (ILP) models for the implementation of the proposed schemes are formulated. Extensive performance evaluation conducted in a PCE-based WDM network scenario shows that DPP + BR + PR and DPP + PR can significantly lower the blocking probability value compared to DPP (1:2) without compromising too much in terms of connection availability.
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3.
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4.
  • Bhar, Chayan, 1988, et al. (författare)
  • Channel allocation in elastic optical networks using traveling salesman problem algorithms
  • 2019
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 11:10, s. C58-C66
  • Tidskriftsartikel (refereegranskat)abstract
    • Elastic optical networks have been proposed to support high data rates in metro and core networks. However, frequency allocation of the channels (i.e., channel ordering) in such networks is a challenging problem. This requires arranging the optical channels within the frequency grid with the objective of ensuring a minimum signal-to-noise ratio (SNR). An optimal arrangement results in the highest SNR margin for the entire network. However, determining the optimal arrangement requires an exhaustive search through all possible arrangements (permutations) of the channels. The search space increases exponentially with the number of channels. This discourages an algorithm employing an exhaustive search for the optimal frequency allocation. We utilize the Gaussian noise (GN) model to formulate the frequency allocation (channel ordering) problem as a variant of the traveling salesman problem (TSP) using graph theory. Thereafter, we utilize graph-theoretic tools for the TSP from the existing literature to solve the channel ordering problem. Performance figures obtained for the proposed scheme show that it is marginally inferior to the optimal search (through all possible permutations) and outperforms any random allocation scheme. Moreover, the proposed scheme is implementable for a scenario with a large number of channels. In comparison, an exhaustive search with the GN model and split-step Fourier method simulations are shown to be feasible for a small number of channels only. It is also illustrated that the SNR decreases with an increase in bandwidth when the frequency separation is high.
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5.
  • Casellas, Ramon, et al. (författare)
  • Introduction to the ONDM2020 special issue
  • 2021
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 13:6, s. ONDM1-ONDM2
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This JOCN special issue includes extended versions of selected papers that were presented at the 24th International Conference on Optical Network Design and Modeling (ONDM2020), which took place virtually on May 18-21, 2020. The topics covered by the papers represent clear trends in current optical networking research including filterless optical networks and their applicability in metropolitan scenarios; programmable, software-defined-networking-enabled sliceable bandwidth variable transceivers supporting multi-dimensionality; and two applications of machine learning-the cognitive reconfiguration of data-center networks in support of high-performance computing, and quality of transmission estimation for reduced margins.
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6.
  • Chen, Jiajia, et al. (författare)
  • Joint Bandwidth Scheduling to Support Differentiated Services and Multiple Service Providers in 1G and 10G EPONs
  • 2009
  • Ingår i: Journal of Optical Communications and Networking. - : The Optical Society. - 1943-0620 .- 1943-0639. ; 1:4, s. 343-351
  • Tidskriftsartikel (refereegranskat)abstract
    • Dynamic bandwidth allocation (DBA) is one of the key issues for the current (1G) and next-generation (10G) Ethernet-based passive optical network (EPON) systems. We present a novel bandwidth scheduling scheme that integrates specific scheduling implementations in the optical line terminal and optical network units. This scheduling enables multiservice access with scalable quality of service support for the triple-play (video, voice, and data) services and open access. Our simulation results show that the proposed scheduling algorithm performs very well in supporting service differentiation and fair allocation of bandwidth to different service providers. A performance comparison between 1G and 10G systems is also presented. To the best of our knowledge, no detailed study of DBA in a 10G EPON can be found in the literature so far.
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7.
  • Chen, Jiajia, et al. (författare)
  • Scalable Passive Optical Network Architecture for Reliable Service Delivery
  • 2011
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 3:9, s. 667-673
  • Tidskriftsartikel (refereegranskat)abstract
    • A scalable and reliable architecture for both a wavelength division multiplexing passive optical network and a hybrid wavelength and time division multiplexing passive optical network with self-healing capability is presented and evaluated. Our protection scheme is compatible with a cascaded arrayed waveguide grating that can accommodate an ultra-large number of end users. A simple interconnection pattern between two adjacent optical network units (ONUs) is applied in order to provide protection for distributed fibers between a remote node and the ONUs. Therefore, the investment cost on a per-user basis can be significantly reduced. Meanwhile, the performance evaluation shows that our approach can achieve high connection availability while maintaining the support of long reach and high splitting ratio.
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8.
  • Chen, Ling, et al. (författare)
  • Reliable and efficient RAR-based distributed model training in computing power network
  • 2024
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 16:5, s. 527-540
  • Tidskriftsartikel (refereegranskat)abstract
    • The computing power network (CPN) is a novel network technology that integrates computing power from the cloud, edge, and terminals using IP/optical cross-layer networks for distributed computing. CPNs can provide an effective solution for distributed model training (DMT). As a bandwidth optimization architecture based on data parallelism, ring all-reduce (RAR) is widely used in DMT. However, any node or link failure on the ring can interrupt or block the requests deployed on the ring. Meanwhile, due to the resource competition of batch RAR-based DMT requests, inappropriate scheduling strategies will also lead to low training efficiency or congestion. As far as we know, there is currently no research that considers the survivability of rings in scheduling strategies for RAR-based DMT. To fill this gap, we propose a scheduling scheme for RAR-based DMT requests in CPNs to optimize the allocation of computing and wavelength resources considering the time dimension while ensuring reliability. In practical scenarios, service providers may focus on different performance metrics. We formulate an integer linear programming (ILP) model and a RAR-based DMT deployment algorithm (RDDA) to solve this problem considering four optimization objectives under the premise of the minimum blocking rate: minimum computing resource consumption, minimum wavelength resource consumption, minimum training time, and maximum reliability. Simulation results demonstrate that our model satisfies the reliability requirements while achieving corresponding optimal performance for DMT requests under four optimization objectives.
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9.
  • Cheng, Yuxin, et al. (författare)
  • POTORI : A Passive Optical Top-of-Rack Interconnect Architecture for Data Centers
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0620 .- 1943-0639. ; 9:5, s. 401-411
  • Tidskriftsartikel (refereegranskat)abstract
    • Several optical interconnect architectures inside data centers (DCs) have been proposed to efficiently handle the rapidly growing traffic demand. However, not many works have tackled the interconnects at top-of-rack (ToR), which have a large impact on the performance of the data center networks (DCNs) and can introduce serious scalability limitations due to their high cost and power consumption. In this paper, we propose a passive optical ToR interconnect architecture (POTORI) to replace the conventional electronic packet switch (EPS) in the access tier of DCNs. In the data plane, POTORI relies on a passive optical coupler to interconnect the servers within the rack and interfaces toward the aggregation/core tiers. The POTORI control plane is based on a centralized rack controller responsible for managing the communications among the servers in the rack. We propose a cycle-based medium access control (MAC) protocol to efficiently manage the exchange of control messages and the data transmission inside the rack. We also introduce and evaluate a dynamic bandwidth allocation algorithm for POTORI, namely largest first (LF). Extensive simulation results show that, with the use of fast tunable optical transceivers, POTORI and the proposed LF strategy are able to achieve an average packet delay below 10 μs under realistic DC traffic scenarios, outperforming conventional EPSs. On the other hand, with slower tunable optical transceivers, a careful configuration of the network parameters (e.g., maximum cycle time of the MAC protocol) is necessary to obtain a good network performance in terms of the average packet delay.
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10.
  • Dharmaweera, Madushanka Nishan, 1986, et al. (författare)
  • Traffic-grooming- and multipath-routing-enabled impairment-aware elastic optical networks
  • 2016
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 8:2, s. 58-70
  • Tidskriftsartikel (refereegranskat)abstract
    • Traffic grooming and multipath routing are two techniques that are widely adopted to increase the performance of traditional wavelength division multiplexed networks. They have been recently applied in elastic optical networks to increase spectral efficiency. In this study, we investigate the potential gains by jointly employing the two techniques in combination with a realistic physical impairment model. To allocate resources and quantify spectral efficiency gains over existing impairment-aware schemes, we present an analytical optimization formulation for small networks and a heuristic for large networks. Through numerical simulations, we demonstrate that traffic grooming and multipath routing, together, increase spectral efficiency and reduce resource consumption over existing schemes. We show that the proposed scheme offers significant performance improvements in networks with low degrees of connectivity, high traffic loads, and long links.
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11.
  • Di Pascale, Emanuele, et al. (författare)
  • Locality-Aware Peer-to-Peer Multimedia Delivery Over Next-Generation Optical Networks
  • 2014
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 6:9, s. 782-792
  • Tidskriftsartikel (refereegranskat)abstract
    • The increasing success of multimedia services poses a serious challenge to both network operators and service providers. Traditional copper-based access technologies are being replaced by fiber-to-the-X (FTTX) deployments in order to meet this increasing bandwidth demand of individual users. However, the growing traffic volume in the access segment may overload the existing aggregation part of the network, therefore creating a bandwidth bottleneck in the core. To address this problem the traffic should be kept as much as possible in the access network, taking advantage of the high-capacity fiber infrastructure. Since multimedia traffic is dominating the network, locality-aware approaches to video content distribution can represent a good solution. In this work, we propose and evaluate a network-managed, peer-to-peer based caching scheme for multimedia distribution. Our results show that such a system is able to reduce core traffic compared to the traditional content delivery network (CDN) based strategies, while at the same time decreasing the overall power consumption of the network and offering cost-saving opportunities for operators.
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12.
  • Dutta, Sourav, et al. (författare)
  • Performance analysis of the limited bandwidth allocation scheme with excess distribution
  • 2019
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 11:6, s. 307-321
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2009-2012 OSA. The limited scheme with excess distribution (LS-ED), being a superior grant-sizing protocol in terms of average delay minimization while providing fairness and quality of service (QoS) satisfaction in Ethernet passive optical networks (EPONs), has already been deployed in diverse technologies. An analysis of the protocol is of paramount importance for obtaining deeper insight into several network design and deployment aspects. Thus, the primary objective of this paper is to perform a rigorous mathematical analysis of LS-ED, for the first time to the best of our knowledge, with the help of a discrete time Markov chain (DTMC). Owing to the dependency of the grant size of a particular optical network unit (ONU) on the queue length of other ONUs, the exact queuing analysis of this scheme necessitates solving a Markov model of the same dimension as the number of ONUs, which makes the analysis complicated and mathematically intractable. A lower-dimensional valid approximation model may allow us to perform such an analysis. In this paper, for the first time to the best of our knowledge, we present an analysis of the scheme, wherein the system dynamics are captured from the perspective of the scheduler leading to an approximate model. The model aids in obtaining a closed-form expression for the average cycle time and throughput along with closed-form expressions for average buffer occupancy and average delay at low load. Finally, we provide useful design insights for EPONs employing LS-ED.
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13.
  • Dzanko, Matija, et al. (författare)
  • Evaluating Availability of Optical Networks Based on Self-Healing Network Function Programmable ROADMs
  • 2014
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 6:11, s. 974-987
  • Tidskriftsartikel (refereegranskat)abstract
    • Due to the large transmission speeds and enormous volume of transferred data, network reliability performance and cost-efficiency are among the key concerns in optical network design. Reducing the number of used optical components with higher failure probability within nodes represents a promising approach for achieving reliable and cost-effective optical network operation as it reduces the correlated risk of connection failures and enables reusing idle components as redundancy for failure recovery. This can result in greater overall network availability and lower loss of data and related revenue. Recently introduced synthetic network function programmable optical nodes implemented by architecture on demand (AoD) support the aforementioned approach by offering high levels of flexibility, modularity, and scalability. In AoD nodes, an optical backplane (i.e., optical switch) hosts optical components and enables arbitrary node configurations by cross-connecting attached modules. As a result, each lightpath passing through the node uses only the components necessary for fulfilling the switching and processing requirements. AoD nodes can perform switching at the wavelength and waveband granularity and also support switching of lightpaths at the fiber level by connecting an input fiber directly to the targeted output, referred to as fiber switching (FS). The latter functionality is particularly beneficial for the availability aspect, as it helps decrease the number of failure-prone components traversed by each lightpath, allowing them to be reused as redundancy. In this paper we demonstrate and evaluate self-healing capabilities of AoD nodes arising from their flexibility and ability to employ idle components for failure recovery. To improve efficiency of self-healing by increasing the number of idle components within nodes, we propose a routing algorithm which obtains a targeted portion of lightpaths switched at the fiber level, called the enforced FS (EFS) algorithm. We study the impact of AoD on network availability at different traffic switching granularities and compare it to traditional hard-wired node architecture via simulation. The results show significant improvements of availability and recovery time due to node-level restoration, with reduced network outage time and operator revenue losses. Finally, to the best of our knowledge, for the first time we experimentally demonstrate two novel hard-wired and synthetic reconfigurable optical add-drop multiplexer architectures with redundancy and all-optical self-healing capabilities.
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14.
  • Etezadi, Ehsan, 1993, et al. (författare)
  • Deep reinforcement learning for proactive spectrum defragmentation in elastic optical networks [Invited]
  • 2023
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 15:10, s. E86-E96
  • Tidskriftsartikel (refereegranskat)abstract
    • The immense growth of Internet traffic calls for advanced techniques to enable the dynamic operation of optical networks, efficient use of spectral resources, and automation. In this paper, we investigate the proactive spectrum defragmentation (SD ) problem in elastic optical networks and propose a novel deep reinforcement learning-based framework DeepDefrag to increase spectral usage efficiency. Unlike the conventional, often threshold-based heuristic algorithms that address a subset of the defragmentation related tasks and have limited automation capabilities, DeepDefrag jointly addresses the three main aspects of the SD process: determining when to perform defragmentation, which connections to reconfigure, and which part of the spectrum to reallocate them to. By considering services attributes, spectrum occupancy state expressed by several different fragmentation metrics, as well as reconfiguration cost, DeepDefragmis able to consistently select appropriate reconfiguration actions over the network lifetime and adapt to changing conditions. Extensive simulation results reveal superior performance of the proposed scheme over a scenario with exhaustive defragmentation and a well-known benchmark heuristic from the literature, achieving lower blocking probability at a smaller defragmentation overhead.
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15.
  • Fan, Yuchuan, et al. (författare)
  • Experimental validation of CNNs versus FFNNs for time- and energy-efficient EVM estimation in coherent optical systems
  • 2021
  • Ingår i: Journal of Optical Communications and Networking. - : OPTICAL SOC AMER. - 1943-0620 .- 1943-0639. ; 13:10, s. E63-E71
  • Tidskriftsartikel (refereegranskat)abstract
    • Error vector magnitude (EVM) has proven to be one of the optical performance monitoring metrics providing the quantitative estimation of error statistics. However, the EVM estimation efficiency has not been fully exploited in terms of complexity and energy consumption. Therefore, in this paper, we explore two deep-learning-based EVM estimation schemes. The first scheme exploits convolutional neural networks (CNNs) to extract EVM information from images of the constellation diagram in the in-phase/quadrature (IQ) complex plane or amplitude histograms (AHs). The second scheme relies on feedforward neural networks (FFNNs) extracting features from a vectorized representation of AHs. In both cases, we use short sequences of 32 Gbaud m-ary quadrature amplitude modulation (mQAM) signals captured before or after a carrier phase recovery. The impacts of the sequence length, neural network structure, and data set representation on the EVM estimation accuracy as well as the model training time are thoroughly studied. Furthermore, we validate the performance of the proposed schemes using the experimental implementation of 28 Gbaud 64QAM signals. We achieve a mean absolute estimation error below 0.15%, with short signals consisting of only 100 symbols per IQ cluster. Considering the estimation accuracy, the implementation complexity, and the potential energy savings, the proposed CNN- and FFNN-based schemes can be used to perform time-sensitive and accurate EVM estimation for mQAM signal quality monitoring purposes.
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16.
  • Fan, Yuchuan, et al. (författare)
  • Fast signal quality monitoring for coherent communications enabled by CNN-based EVM estimation
  • 2021
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers Inc.. - 1943-0620 .- 1943-0639. ; 13:4, s. B12-B20
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a fast and accurate signal quality monitoring scheme that uses convolutional neural networks for error vector magnitude (EVM) estimation in coherent optical communications. We build a regression model to extract EVM information from complex signal constellation diagrams using a small number of received symbols. For the additive-white-Gaussian-noise-impaired channel, the proposed EVM estimation scheme shows a normalized mean absolute estimation error of 3.7% for quadrature phase-shift keying, 2.2% for 16-Ary quadrature amplitude modulation (16QAM), and 1.1% for 64QAM signals, requiring only 100 symbols per constellation cluster in each observation period. Therefore, it can be used as a low-complexity alternative to conventional bit-error-rate estimation, enabling solutions for intelligent optical performance monitoring. 
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17.
  • Fiorani, Matteo, et al. (författare)
  • Abstraction Models for Optical 5G Transport Networks
  • 2016
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 8:9, s. 656-665
  • Tidskriftsartikel (refereegranskat)abstract
    • The orchestration of radio, transport, and cloud resources is a key enabler for efficient service delivery in 5G networks. Orchestration can be achieved with a hierarchical software-defined networking (SDN) control architecture in which a global orchestrator operates above the domain controllers. In such an architecture, the abstraction of resources between the controllers and the orchestrator plays a fundamental role for the system performance. In order to reduce the orchestrator complexity, the controllers should hide as much detail as possible from the orchestrator. On the other hand, the more details are available to the orchestrator the more optimal resource orchestration strategy can be obtained. In order to assess this trade-off, we recently proposed two transport abstraction models, namely big switch (BiS) and virtual link (VL), for centralized radio access networks (C-RANs) with orchestration of radio and transport resources. We observed that VL can provide a more efficient resource orchestration than BiS at the expense of an increased implementation complexity. The contribution of this paper is twofold. We extend the BiS and VL models to make them applicable to any orchestration scenario. Then, we propose a new transport abstraction model, referred to as optical transport transformation (OTT), that aims at achieving efficient resource orchestration with a reduced implementation complexity. We compare the performance of these new abstraction models in a C-RAN use case in which backhaul and fronthaul traffic are carried over a dense wavelength division multiplexing (DWDM) network. Our results prove that in a C-RAN the best choice for the transport abstraction model depends on the availability and the reachability of the radio resources. If radio resources are scarce compared to transport resources, complex transport abstraction models are not needed and a BiS abstraction is the best choice. On the other hand, if radio resources are widely available and reachable, an OTT model guarantees the best overall performance.
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18.
  • Fiorani, Matteo, et al. (författare)
  • Energy Efficiency of an Integrated Intra-Data-Center and Core Network With Edge Caching
  • 2014
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 6:4, s. 421-432
  • Tidskriftsartikel (refereegranskat)abstract
    • The expected growth of traffic demand may lead to a dramatic increase in the network energy consumption, which needs to be handled in order to guarantee scalability and sustainability of the infrastructure. There are many efforts to improve energy efficiency in communication networks, ranging from the component technology to the architectural and service-level approaches. Because data centers and content delivery networks are responsible for the majority of the energy consumption in the information and communication technology sector, in this paper we address network energy efficiency at the architectural and service levels and propose a unified network architecture that provides both intra-data-center and inter-data-center connectivity together with interconnection toward legacy IP networks. The architecture is well suited for the carrier cloud model, where both data-center and telecom infrastructure are owned and operated by the same entity. It is based on the hybrid optical switching (HOS) concept for achieving high network performance and energy efficiency. Therefore, we refer to it as an integrated HOS network. The main advantage of the integration of core and intra-data-center networks comes from the possibility to avoid the energy-inefficient electronic interfaces between data centers and telecom networks. Our results have verified that the integrated HOS network introduces a higher number of benefits in terms of energy efficiency and network delays compared to the conventional nonintegrated solution. At the service level, recent studies demonstrated that the use of distributed video cache servers can be beneficial in reducing energy consumption of intra-data-center and core networks. However, these studies only take into consideration conventional network solutions based on IP electronic switching, which are characterized by relatively high energy consumption. When a more energy-efficient switching technology, such as HOS, is employed, the advantage of using distributed video cache servers becomes less obvious. In this paper we evaluate the impact of video servers employed at the edge nodes of the integrated HOS network to understand whether edge caching could have any benefit for carrier cloud operators utilizing a HOS network architecture. We have demonstrated that if the distributed video cache servers are not properly dimensioned they may have a negative impact on the benefit obtained by the integrated HOS network.
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19.
  • Fiorani, Matteo, et al. (författare)
  • Flexible Network Architecture and Provisioning Strategy for Geographically Distributed Metro Data Centers
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:5, s. 385-392
  • Tidskriftsartikel (refereegranskat)abstract
    • The fifth generation of mobile networks (5G) is expected to introduce new services with strict end-to-end delay requirements. For this reason, service providers and network operators are increasingly relying on geographically distributed metro data centers (DCs) to bring services closer to end-users and reduce delivery time. The metro DCs frequently exchange data for different purposes, such as backup and load balancing. Some of these data transfers require guaranteed low delays. Meanwhile, efficient use of network resources is necessary to limit the cost of the network infrastructure. To address these issues, in this paper, we propose a converged intra-and inter-DC network architecture and a dynamic provisioning strategy that are able to (i) efficiently support different classes of service, (ii) offer fast data transfers among metro DCs, and (iii) enable efficient utilization of network resources. Simulation results show that the proposed network architecture and provisioning strategy achieve at least two times faster average data transfer between DCs and better network resource utilization compared with conventional solutions. We also present a prototype and an extensive set of experimental results, thus proving the implementation feasibility and effectiveness of the proposed approach.
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20.
  • Fiorani, Matteo, et al. (författare)
  • Modeling energy performance of C-RAN with optical transport in 5G network scenarios
  • 2016
  • Ingår i: Journal of Optical Communications and Networking. - : IEEE. - 1943-0620 .- 1943-0639. ; 8:11
  • Tidskriftsartikel (refereegranskat)abstract
    • The deployment of new 5G wireless interfaces based on massive multiantenna transmission and beamforming is expected to have a significant impact on the complexity and power consumption of the transport network. This paper analyzes the energy performance of four radio access network (RAN) architectures, each one utilizing a different option for splitting the baseband processing functions. The radio segment is based on Long-Term Evolution (LTE) and 5G radio access technologies. The transport segment is based on optical wavelength division multiplexing, where coherent and direct detection transmissions are considered. The energy consumption of each RAN architecture is weighted against i) the benefits for the radio segment as a function of the level of centralization of the baseband processing functions and ii) the power consumption levels needed to accommodate the capacity generated at each base station. Results show that, with LTE radio interfaces, the energy consumption of the transport network amounts to only a few percent of the overall network power consumption. As a result, fully centralized LTE radio architectures are a viable option, with energy savings of at least 27% compared with conventional distributed architectures. On the other hand, with advanced 5G radio interfaces, centralized architectures, if not carefully designed, might become impractical due to the excessive energy consumption of the transport network (i.e., as a result of the huge capacity to be accommodated). This aspect can be mitigated via a careful joint design of the radio and the transport network (i.e., leveraging on appropriate optical transmission techniques and compromising where needed on the radio network performance).
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21.
  • Fiorani, Matteo, et al. (författare)
  • Spatial division multiplexing for high capacity optical interconnects in modular data centers
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:2, s. A143-A153
  • Tidskriftsartikel (refereegranskat)abstract
    • Modular design has recently emerged as an efficient solution to build large data center (DC) facilities. Modular DCs are based on stand-Alone prefabricated modules (i.e., PODs) that can be easily installed and interconnected. PODs can generate a large amount of traffic and thus require an ultra-high-capacity interconnection network. However, current electronic and optical interconnect architectures applied to modular DCs may experience major scalability problems in terms of high energy consumption and cabling complexity. To address these problems, we investigate five optical interconnect architectures based on spatial division multiplexing (SDM), and for each architecture, we propose a resource allocation strategy. We also present an extensive comparison among the SDM architectures in terms of cost and performance (i.e., blocking probability and throughput), with the objective to find the architecture offering the best trade-off between cost and performance for given DC sizes and traffic load values. Our results demonstrate that, in small modular DCs with low traffic load, an architecture based only on SDM is the best option, while in medium DCs with medium traffic load, an architecture based on coupled SDM and flexgrid wavelength division multiplexing (WDM) with spectral flexibility is the best solution. Finally, for large DCs with high traffic load values, the best trade-off between cost and performance is achieved by an SDM architecture that is based on uncoupled SDM and flexgrid WDM.
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22.
  • Forzati, Marco, et al. (författare)
  • Next-generation optical access seamless evolution : Concluding results of the European FP7 Project OASE
  • 2015
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers Inc.. - 1943-0620 .- 1943-0639. ; 7:2, s. 109-123
  • Tidskriftsartikel (refereegranskat)abstract
    • Increasing bandwidth demand drives the need for next-generation optical access (NGOA) networks that can meet future end-user service requirements. This paper gives an overview of NGOA solutions, the enabling optical access network technologies, architecture principles, and related economics and business models. NGOA requirements (including peak and sustainable data rate, reach, cost, node consolidation, and open access) are proposed, and the different solutions are compared against such requirements in different scenarios (in terms of population density and system migration). Unsurprisingly, it is found that different solutions are best suited for different scenarios. The conclusions drawn from such findings allow us to formulate recommendations in terms of technology, strategy, and policy. The paper is based on the main results of the European FP7 OASE Integrated Project that ran between January 1, 2010 and February 28, 2013. 
  •  
23.
  • Furdek, Marija, 1985-, et al. (författare)
  • Attack-aware wavelength assignment for localization of in-band crosstalk attack propagation
  • 2010
  • Ingår i: Journal of Optical Communications and Networking. - : IEEE Press. - 1943-0620 .- 1943-0639. ; 2:11, s. 1000-1009
  • Tidskriftsartikel (refereegranskat)abstract
    • The high data rates employed by wavelength division multiplexing transparent optical networks make them most suitable for today's growing network traffic demands. However, their transparency imposes several vulnerabilities in network security, enabling malicious signals to propagate from the source to other parts of the network without losing their attacking capabilities. Furthermore, detecting, locating the source, and localizing the spreading of such physical-layer attacks is more difficult since monitoring must be performed in the optical domain. While most failure and attack management approaches focus on network recovery after a fault or an attack has already occurred, we suggest a novel safety strategy, proposing a prevention-oriented method to aid attack localization and source identification in the planning phase. In this paper, we propose attack-aware wavelength assignment that minimizes the worst-case potential propagation of in-band crosstalk jamming attacks. We define a new objective criterion for the wavelength assignment (WA) problem, called the propagating crosstalk attack radius (P-CAR), and develop heuristic algorithms aimed at minimizing both the P-CAR and the number of wavelengths used. Our aim is to achieve better protection, but without the need for extra resources. We compare our algorithms with existing WA approaches, illustrating their benefits with respect to transparent optical networks' security, as well as the associated wavelength utilization.
  •  
24.
  • Furdek Prekratic, Marija, 1985, et al. (författare)
  • Introduction to the ONDM 2021 special issue
  • 2022
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 14:5, s. ONDM1-ONDM2
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This JOCN special issue contains extended versions of selected papers presented at the 25th International Conference on Optical Network Design and Modeling (ONDM 2021), which took place virtually from 28 June through 1 July 2021. The topics covered by the papers represent clear trends in current optical networking research, including capacity upgrade through transmission parameter optimization in multiband systems, spectral efficiency improvement through probabilistic constellation shaping in Flex Grid/multicore fiber networks, novel point-to-multipoint optical architectures based on digital subcarrier multiplexing that enable a rethink of multilayer network design, and trustworthy inter-operator sharing of passive optical network capacity based on a smart contract.
  •  
25.
  • Furdek Prekratic, Marija, 1985, et al. (författare)
  • Introduction to the Photonic Networks and Devices (NETWORKS) Special Issue
  • 2020
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 12:4, s. NET1-NET2
  • Tidskriftsartikel (refereegranskat)abstract
    • This special issue comprises extended versions of some of the top-scored papers that were presented at the OSA Photonic Networks and Devices (NETWORKS) meeting that was part of the OSA Advanced Photonics Congress held in Burlingame, California, USA, July 29–August 1, 2019. Here, we highlight relevant topics from included papers relating to photonic communication network development.
  •  
26.
  • Furdek Prekratic, Marija, 1985, et al. (författare)
  • Optical Network Security Management: Requirements, Architecture and Efficient Machine Learning Models for Detection of Evolving Threats [Invited]
  • 2021
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 13:2, s. A144-A155
  • Tidskriftsartikel (refereegranskat)abstract
    • As the communication infrastructure that sustains critical societal services, optical networks need to function in a secure and agile way. Thus, cognitive and automated security management functionalities are needed, fueled by the proliferating machine learning (ML) techniques and compatible with common network control entities and procedures. Automated management of optical network security requires advancements both in terms of performance and efficiency of ML approaches for security diagnostics, as well as novel management architectures and functionalities. This paper tackles these challenges by proposing a novel functional block called Security Operation Center (SOC), describing its architecture, specifying key requirements on the supported functionalities and providing guidelines on its integration with optical layer controller. Moreover, to boost efficiency of ML-based security diagnostic techniques when processing high-dimensional optical performance monitoring data in the presence of previously unseen physical-layer attacks, we combine unsupervised and semi-supervised learning techniques with three different dimensionality reduction methods and analyze the resulting performance and trade-offs between ML accuracy and run time complexity.
  •  
27.
  • Giorgetti, A., et al. (författare)
  • Segment routing for effective recovery and multi-domain traffic engineering
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0620 .- 1943-0639. ; 9:2, s. A223-A232
  • Tidskriftsartikel (refereegranskat)abstract
    • Segment routing is an emerging traffic engineering technique relying on Multi-protocol Label-Switched (MPLS) label stacking to steer traffic using the source-routing paradigm. Traffic flows are enforced through a given path by applying a specifically designed stack of labels (i.e., the segment list). Each packet is then forwarded along the shortest path toward the network element represented by the top label. Unlike traditional MPLS networks, segment routing maintains a per-flow state only at the ingress node; no signaling protocol is required to establish new flows or change the routing of active flows. Thus, control plane scalability is greatly improved. Several segment routing use cases have recently been proposed. As an example, it can be effectively used to dynamically steer traffic flows on paths characterized by low latency values. However, this may suffer from some potential issues. Indeed, deployed MPLS equipment typically supports a limited number of stacked labels. Therefore, it is important to define the proper procedures to minimize the required segment list depth. This work is focused on two relevant segment routing use cases: dynamic traffic recovery and traffic engineering in multi-domain networks. Indeed, in both use cases, the utilization of segment routing can significantly simplify the network operation with respect to traditional Internet Protocol (IP)/MPLS procedures. Thus, two original procedures based on segment routing are proposed for the aforementioned use cases. Both procedures are evaluated including a simulative analysis of the segment list depth. Moreover, an experimental demonstration is performed in a multi-layer test bed exploiting a software-defined-networking-based implementation of segment routing.
  •  
28.
  • Grigoreva, Elena, et al. (författare)
  • Energy Consumption and Reliability Performance of Survivable Passive Optical Converged Networks: Public ITS Case Study
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:4, s. C98-C107
  • Tidskriftsartikel (refereegranskat)abstract
    • Access networks are evolving fast by increasing their capacity and coverage area, coping with a larger number of users and variety of terminals. Operators aim at keeping high network performance and quality of service but limiting their capital and operational expenditures by, e.g., minimizing investments and energy consumption using power saving at the network components. To address these challenges this paper evaluates the energy consumption, connection availability, and failure detection time of three protection schemes applicable for converged access networks: disjoint fiber protection, energy-efficient disjoint fiber protection, and reflective disjoint fiber protection. The schemes are assessed by a case study considering a public intelligent transport system (ITS). The studied ITS deploys a dedicated short-range communications radio access network connected to the service server through a protected passive access network. Comparison with unprotected architecture shows that reflective disjoint fiber protection offers low energy consumption and high connection availability, while it significantly reduces the failure detection time and, hence, the connection interruption time.
  •  
29.
  • Grover, Wayne, et al. (författare)
  • Call for Papers : High Availability in Optical Networks
  • 2006
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 5:1, s. 75-76
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The Journal of Optical Networking (JON) is soliciting papers for a feature Issue pertaining to all aspects of reliable components and systems for optical networks and concepts, techniques, and experience leading to high availability of services provided by optical networks. Most nations now recognize that telecommunications in all its forms -- including voice, Internet, video, and so on -- are "critical infrastructure" for the society, commerce, government, and education. Yet all these services and applications are almost completely dependent on optical networks for their realization. "Always on" or apparently unbreakable communications connectivity is the expectation from most users and for some services is the actual requirement as well. Achieving the desired level of availability of services, and doing so with some elegance and efficiency, is a meritorious goal for current researchers. This requires development and use of high-reliability components and subsystems, but also concepts for active reconfiguration and capacity planning leading to high availability of service through unseen fast-acting survivability mechanisms. The feature issue is also intended to reflect some of the most important current directions and objectives in optical networking research, which include the aspects of integrated design and operation of multilevel survivability and realization of multiple Quality-of-Protection service classes. Dynamic survivable service provisioning, or batch re-provisioning is an important current theme, as well as methods that achieve high availability at far less investment in spare capacity than required by brute force service path duplication or 100% redundant rings, which is still the surprisingly prevalent practice. Papers of several types are envisioned in the feature issue, including outlook and forecasting types of treatments, optimization and analysis, new concepts for survivability, or papers on availability analysis methods or results. Customer, vendor, and researcher viewpoints and priorities will all be given consideration. Especially valuable to the community would be papers that include or provide measured data on actual reliability and availability performance of optical networking components or systems.Scope of SubmissionThe scope of the papers includes, but is not limited to, the following topics:Reliability and availability measurement techniques specific to optical network devices or services.Data on SRLG statistics and frequency of different actual failure causes.Real-life accounts or data on failure and repair rates or projected values for use in availability analysis.Availability analysis methods, especially for survivable networks with reconfigurable or adaptive failure-specific responses.Availability analysis and comparisons of basic schemes for survivability.Differentiated availability schemes.Design for Multiple Quality of Protection.Different schemes for on-demand survivable service provisioning.Basic comparisons or proposals of new survivability mechanisms and architectures.Concepts yielding higher than 1+1 protection switching availability at less than 100% redundancy.Survivable service provisioning in domains of optical transparency: dealing with signal impairments.Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON, indicating "Feature Issue: Optical Network Availability" in the "Comments" field of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line "Feature Issue: Optical Network Availability." Additional information can be found on the JON website: http://www.osa-jon.org/submission/.
  •  
30.
  • Grover, Wayne, et al. (författare)
  • Call for Papers : High Availability in Optical Networks
  • 2005
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 4:12, s. 874-875
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The Journal of Optical Networking (JON) is soliciting papers for a feature Issue pertaining to all aspects of reliable components and systems for optical networks and concepts, techniques, and experience leading to high availability of services provided by optical networks. Most nations now recognize that telecommunications in all its forms -- including voice, Internet, video, and so on -- are "critical infrastructure" for the society, commerce, government, and education. Yet all these services and applications are almost completely dependent on optical networks for their realization. "Always on" or apparently unbreakable communications connectivity is the expectation from most users and for some services is the actual requirement as well. Achieving the desired level of availability of services, and doing so with some elegance and efficiency, is a meritorious goal for current researchers. This requires development and use of high-reliability components and subsystems, but also concepts for active reconfiguration and capacity planning leading to high availability of service through unseen fast-acting survivability mechanisms. The feature issue is also intended to reflect some of the most important current directions and objectives in optical networking research, which include the aspects of integrated design and operation of multilevel survivability and realization of multiple Quality-of-Protection service classes. Dynamic survivable service provisioning, or batch re-provisioning is an important current theme, as well as methods that achieve high availability at far less investment in spare capacity than required by brute force service path duplication or 100% redundant rings, which is still the surprisingly prevalent practice. Papers of several types are envisioned in the feature issue, including outlook and forecasting types of treatments, optimization and analysis, new concepts for survivability, or papers on availability analysis methods or results. Customer, vendor, and researcher viewpoints and priorities will all be given consideration. Especially valuable to the community would be papers that include or provide measured data on actual reliability and availability performance of optical networking components or systems.Scope of SubmissionThe scope of the papers includes, but is not limited to, the following topics: Reliability and availability measurement techniques specific to optical network devices or services. Data on SRLG statistics and frequency of different actual failure causes. Real-life accounts or data on failure and repair rates or projected values for use in availability analysis. Availability analysis methods, especially for survivable networks with reconfigurable or adaptive failure-specific responses. Availability analysis and comparisons of basic schemes for survivability. Differentiated availability schemes. Design for Multiple Quality of Protection. Different schemes for on-demand survivable service provisioning. Basic comparisons or proposals of new survivability mechanisms and architectures. Concepts yielding higher than 1+1 protection switching availability at less than 100% redundancy. Survivable service provisioning in domains of optical transparency: dealing with signal impairments. Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON, indicating "Feature Issue: Optical Network Availability" in the "Comments" field of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line "Feature Issue: Optical Network Availability." Additional information can be found on the JON website: http://www.osa-jon.org/submission/.
  •  
31.
  • Hadi, Mohammad, 1989, et al. (författare)
  • Dynamic Resource Allocation in Metro Elastic Optical Networks using Lyapunov Drift Optimization
  • 2019
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 11:6, s. 250-259
  • Tidskriftsartikel (refereegranskat)abstract
    • Consistent growth in the volume and dynamic behavior of traffic mandates new requirements for fast and adaptive resource allocation in metro networks. We propose a dynamic resource allocation technique for adaptive minimization of spectrum usage in metro elastic optical networks. We consider optical transmission as a service specified by its bandwidth profile parameters, which are minimum, average, and maximum required transmission rates. To consider random traffic events, we use a stochastic optimization technique to develop a novel formulation for dynamic resource allocation in which service level specifications and network stability constraints are addressed. Next, we employ the elegant theory of Lyapunov optimization to solve the stochastic optimization problem and derive a fast integer linear program, which is periodically solved to create an adaptation between available resources and dynamic network state. To quantize the performance of the proposed technique, we report its spectral efficiency as a function of peak to average traffic ratio and Lyapunov penalty coefficient. Simulation results show that the dynamic resource allocation procedure can improve spectral efficiency by a factor of 3.3 for a peak to average traffic ratio of 1.37 and a Lyapunov penalty coefficient of 1000 in comparison with fixed network planning. There is also a trade-off between transmission delay and spectrum utilization in the proposed technique, which can be adjusted by a Lyapunov penalty coefficient.
  •  
32.
  • Hadi, Mohammad, 1989, et al. (författare)
  • General QoS-Aware Scheduling Procedure for Passive Optical Networks
  • 2020
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 12:7, s. 217-226
  • Tidskriftsartikel (refereegranskat)abstract
    • Increasing volume, dynamism, and diversity of access traffic have complicated the challenging problem of dynamic resource allocation in passive optical networks. We introduce a general scheduling procedure for passive optical networks, which optimizes a desired performance metric for an arbitrary set of operational constraints. The proposed scheduling has a fast and causal iterative implementation, where each iteration involves a local optimization problem followed by a recursive update of some status information. The generality of the platform enables a proper description of the diverse quality of service requirements, while its low computational complexity makes agile tracking of the network dynamism possible. To demonstrate its versatility and generality, the applications of the scheme for service-differentiated dynamic bandwidth allocation in time- and wavelength-division-multiplexed passive optical networks are discussed. To further reduce the computational complexity, a closed-form solution of the involved optimization in each iteration of the scheduling is derived. We directly incorporate transmission delay in the scheduling and show how the consumed power is traded for the tolerable amount of transmission delay. Furthermore, a 50% power efficiency improvement is reported by exploiting the inherent service diversity among subscribers. The impact of service prioritization, finite buffer length, and packet drops on the power efficiency of the scheme are also investigated.
  •  
33.
  • Hadi, Mohammad, 1989, et al. (författare)
  • Joint Power-Efficient Traffic Shaping and Service Provisioning for Metro Elastic Optical Networks
  • 2019
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 11:12, s. 578-587
  • Tidskriftsartikel (refereegranskat)abstract
    • Considering the time-averaged behavior of a metro elastic optical network, we develop a joint procedure for resource allocation and traffic shaping to exploit the inherent service diversity among the requests for power-efficient network operation. To support the quality of service diversity, we consider minimum transmission rate, average transmission rate, maximum burst size, and average transmission delay as the adjustable parameters of a general service profile. The work evolves from a stochastic optimization problem, which minimizes the power consumption subject to stability, physical, and service constraints. The optimal solution of the problem is obtained using a complex dynamic programming method. To provide a near-optimal fast-achievable solution, we propose a sequential heuristic with a scalable and causal software implementation, according to the basic Lyapunov iterations of an integer linear program. The heuristic method has a negligible optimality gap and a considerably shorter runtime compared to the optimal dynamic programming, and reduces the consumed power by 72% for an offered traffic with a unit variation coefficient. The adjustable trade-offs of the proposed scheme offer a typical 10% power saving for an acceptable amount of excess transmission delay or drop rate.
  •  
34.
  • Hong, Xuezhi, et al. (författare)
  • Passive Optical Interconnects Based on Cascading Wavelength Routing Devices for Datacenters : A Cross-Layer Perspective
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:4, s. C45-C53
  • Tidskriftsartikel (refereegranskat)abstract
    • A general passive optical interconnect (POI) architecture based on cascading wavelength routing devices is proposed for datacenters. An analysis shows that with a proper port configuration, the logic topology of the proposed POI is equivalent to a DCell network, which has rich connectivity, leading to a high fault tolerance. Compared with the existing arrayed waveguide grating (AWG)-based architecture, such as H-LION, the proposed architecture has a higher AWG port utilization and lower cabling complexity that result in better scalability. Meanwhile, an impairment-aware scalability analysis is carried out to estimate the impact of in-band crosstalk on the size of the POI. Furthermore, a cross-layer investigation of the proposed POI provides a guideline to select proper physical-layer implementations, including optical interface structure and design of the transceiver, for acceptable network performance. The numerical results reveal that, with a moderate number of shortest paths K and degrees of node D, (a) the bidirectional optical interface is more suitable for large-scale datacenter networks than the unidirectional one, (b) an array of fixed receivers can be replaced by just a small number of tunable receivers with negligible degradation in network performance, and (c) decreasing 50% of the tuning range of the receivers causes only a minor increase of blocking probability, which demonstrates a good balance between the complexity of the transceiver design and network performance.
  •  
35.
  • Hong, Yuanyuan, et al. (författare)
  • Hybrid Routing and Adaptive Spectrum Allocation for Flex-Grid Optical Interconnects
  • 2018
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 10:5, s. 506-514
  • Tidskriftsartikel (refereegranskat)abstract
    • A hybrid routing scheme with an adaptive spectrum assignment is proposed for flex-grid all-optical core switch supporting multihop transparent paths in data center networks. Compared with conventional spectrum assignment algorithms (RSA) developed for a multihop network with optical-electric-optical (OEO) conversion in every hop (i.e., RSA for EO) and that devised for an all-optical multihop network (i.e., RSA for AO), the present RSA algorithm provides better utilization of network resources. Being aware of the all-optical bypass path in hopping, the proposed RSA reduces the blocking probability due to lack of bandwidth-tunable transceivers, which is the major reason for blocking for an RSA for the EO. Similar to the RSA for the AO, the proposed RSA is compatible with the number-of-hops adaptive spectrum assignment, which improves spectrum efficiency. On the other hand, the new algorithm enhances connectivity by eliminating the number-of-hops limitation, which severely constrains the performance of RSA for the AO. Simulations for the system are carried out to investigate the performance of the new algorithm. The impacts of various parameters, such as traffic load, ratio of connection requests with different data rates, and resource configuration on the link cost, are studied in terms of network blocking probability (BP). The achievable traffic load of the proposed RSA under varied connection degrees (i.e., the maximum number of ports that one rack has in order to connect to the core switch) and number of racks is also assessed to keep BP no more than 0.1. The results show that the proposed RSA with appropriate cost functions outperforms the EO and AO, which implies that it has the highest scalability.
  •  
36.
  • Johannisson, Pontus, 1976, et al. (författare)
  • Convergence Comparison of the CMA and ICA for Blind Polarization Demultiplexing
  • 2011
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 3:6, s. 493-501
  • Tidskriftsartikel (refereegranskat)abstract
    • An algorithm based on independent component analysis for blind polarization demultiplexing in a coherent transmission system is presented. A comparison with the constant modulus algorithm in terms of the convergence properties is performed, and it is found that the suggested algorithm has a significantly faster convergence rate and does not have any singularity problems. We also demonstrate that the algorithm convergence is strongly dependent on the choice of starting condition and show how this can be exploited to increase the convergence rate.
  •  
37.
  • Keykhosravi, Kamran, 1990, et al. (författare)
  • Multicast scheduling of wavelength-tunable, multiqueue optical data center switches
  • 2018
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 10:4, s. 353-364
  • Tidskriftsartikel (refereegranskat)abstract
    • The all-optical switching of multicast flows using star couplers and tunable transceivers is a promising solution for emerging cloud data center applications. However, the limited tuning range of optical components on one hand and the buffer management challenges for multicast traffic delivery on the other pose a significant impact on the performance of optical multicast scheduling algorithms. Using only one queue per input port results in head-of-line (HOL) blocking and limits the throughput, especially for bursty traffic patterns. As the number of possible multicast destinations grows exponentially with the switch size, allocating one queue per destination is not a feasible solution. To resolve HOL blocking, in this paper we consider only a handful of queues per switch input port and devise scalable scheduling algorithms that take into account transceiver tunability constraints. According to our Monte Carlo analysis of a switch with 64 ports and operating under bursty traffic, it is possible to improve the maximum achievable throughput by 44% when the number of queues per port is increased from one to eight. We show that the performance gains due to an increase in the queue count depend on the availability of the spectral resources. With the scarcity of wavelengths, an increase in the number of queues leads to diminishing returns.
  •  
38.
  •  
39.
  • Lashgari, Maryam, 1991, et al. (författare)
  • Techno-economics of Fiber vs. Microwave for Mobile Transport Network Deployments [Invited]
  • 2023
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 15:7, s. C74-C87
  • Tidskriftsartikel (refereegranskat)abstract
    • One of the challenges for network operators is to design and deploy cost-efficient transport networks (TNs) to meet the high capacity and strict latency/reliability requirements of today’s emerging services. Therefore, they need to consider different aspects, including the appropriate technology, the level of reconfigurability, and the functional split option. A crucial aspect of network design is assessing the impact of these aspects against the total cost of ownership (TCO), latency, and reliability performance of a given solution. For this reason, this paper proposes a framework to investigate the TCO, latency, and reliability performance of a set of fiber and microwave-based TN architectures. They are categorized based on their baseband functional split option and the reconfigurability capabilities of the equipment used. The results, based on real data from a non-incumbent operator, show that in most of the considered scenarios, a microwavebased TN exhibits lower TCO than a fiber-based one. The TCO gain may vary with the choice of the functional split option, geo-type, reconfigurability features, fiber trenching costs, and cost of microwave equipment, with a more significant impact in a dense urban geo-type, where for a low layer functional split option the fiber- and microwave-based architectures have a comparable TCO. Finally, it was found that the considered fiber and microwave architectures have almost similar average latency and connection availability performance. Both are suitable to meet the service requirements of 5G and beyond 5G services in most of the considered scenarios. Only in extreme latency-critical scenarios, a small number of the cells might not fully satisfy the latency requirements of a low layer split option due to multiple microwave hops in the microwave-based architecture.
  •  
40.
  • Li, Jun, et al. (författare)
  • Delay-aware bandwidth slicing for service migration in mobile backhaul networks
  • 2019
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers Inc.. - 1943-0620 .- 1943-0639. ; 11:4, s. B1-B9
  • Tidskriftsartikel (refereegranskat)abstract
    • Fog computing is expected to be integrated with communication infrastructure, giving rise to the concept of fog-enhanced radio access networks (FeRANs) to support various mission-critical applications. Such architecture brings computation capabilities closer to end users, thereby reducing the communication latency to access services. In the context of FeRAN, service migration is needed to tackle limited resources in a single fog node and to provide continuous service for mobile end users. To support service migration, high capacity and low latency are required in mobile backhaul networks. Passive optical networks can be a promising solution for such mobile back-haul, in which bandwidth is shared by both migration traffic and that which is not associated with service migration. In this paper, we propose a bandwidth slicing mechanism, in which the bandwidth can be provisioned to the migration traffic and non-migration traffic dynamically and effectively to meet their different delay requirements. Simulation results verify that the proposed delay-aware bandwidth slicing scheme can handle the migration traffic properly, i.e., sending it within a required time threshold, while limiting the impact of the migration traffic on the latency and jitter of the non-migration traffic, particularly that with high priority.
  •  
41.
  • Li, Jun, 1988, et al. (författare)
  • Enabling technologies for low-latency service migration in 5G transport networks [Invited]
  • 2021
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers Inc.. - 1943-0620 .- 1943-0639. ; 13:2, s. A200-A210
  • Tidskriftsartikel (refereegranskat)abstract
    • The fifth generation (5G) mobile communications system is envisioned to serve various mission-critical services such as industrial automation, cloud robotics, and safety-critical vehicular communications. To satisfy the stringent end-to-end latency requirement of these services, fog computing has been regarded as a promising technology to be integrated into 5G networks, in which computing, storage, and network functions are provisioned close to end users, thus significantly reducing the latency caused in transport networks. However, in the context of fog-computing-enabled 5G networks, the high mobility feature of users brings critical challenges to satisfy the stringent quality of service requirements. To address this issue, service migration, which transmits the associated services from the current fog server to the target one to follow the users' travel trace and keep the service continuity, has been considered. However, service migration cannot always be completed immediately and may lead to a situation where users experience a loss of service access. In this regard, low-latency service migration plays a key role to reduce the negative effects on services being migrated. In this paper, the factors that affect the performance of service migration are analyzed. To enable low-latency service migration, three main enabling technologies are reviewed, including migration strategies, low-latency, and high-capacity mobile backhaul network design, and adaptive resource allocation. Based on a summary of the reviewed technologies, we conclude that dynamic resource allocation is the worthiest one to research. Therefore, we carry out a use case, where reinforcement learning (RL) is adopted for autonomous bandwidth allocation in support of low-latency service migration in a dynamic traffic environment and evaluate its performance compared to two benchmarks. The simulation demonstrates that the RL-based algorithm is able to self-adapt to a dynamic traffic environment and gets converged performance, which has an obviously smaller impact on non-migration traffic than the two benchmarks while keeping the migration success probability high. Meanwhile, unlike the benchmarks, the RL-based method shows performance fluctuations before getting converged, which may cause unstable system performance. It calls for future research on advanced smart policies that can get convergence quickly, particularly for handling the migration of latency-sensitive services in 5G transport networks. 
  •  
42.
  • Li, Jun, et al. (författare)
  • Passive Optical Network Based Mobile Backhaul Enabling Ultra-Low Latency for Communications Among Base Stations
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:10, s. 855-863
  • Tidskriftsartikel (refereegranskat)abstract
    • Low latency is of key importance for mobile networks to support emerging time-critical applications, such as road traffic safety and efficiency. Meanwhile, a passive optical network (PON) is widely recognized as a promising solution for mobile backhaul networks thanks to its high capacity and low energy consumption. In the conventional PON-based mobile backhaul network, where base stations (BSs) are co-located with optical network units, the traffic between the neighboring BSs that are mainly caused by user mobility has to be first sent to the optical line terminal and even further, e.g., edge nodes of mobile core networks, resulting in high latency, although the adjacent BSs are geographically located close to each other. In this paper, a novel PON-based architecture is proposed for mobile backhaul to enhance the connectivity between neighboring BSs. Meanwhile, a tailored medium access control protocol and dynamic bandwidth allocation algorithm are introduced to support fast inter-BS communications. The results reveal that a low latency (less than 1 ms packet delay) for communications among any adjacent BSs can be achieved in the proposed PON-based mobile backhaul network, demonstrating great potential to support future time-critical applications.
  •  
43.
  • Li, Yajie, et al. (författare)
  • End-to-end URLLC slicing based on packet duplication in 5G optical transport networks
  • 2020
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 12:7, s. 192-199
  • Tidskriftsartikel (refereegranskat)abstract
    • With the stringent requirements of high reliability and low latency, ultra-reliable low latency communications (URLLCs) are one of three typical services in the fifth generation of mobile network (5G) paradigm. The packet duplication (PD) technique has been proposed as a promising solution to satisfy the extreme requirements of URLLC services. However, the benefit of PD comes at the cost of doubling resource usage. This paper investigates how to efficiently perform end-to-end URLLC slicing based on PD in 5G optical transport networks. Two heuristic algorithms are proposed, including PD-based slicing with wavelength isolation (PDS-WI) and PD-based slicing with link isolation (PDS-LI). The target of this paper is to maximize the number of accommodated URLLC slices by optimizing the allocation of heterogenous resources. The time complexity of these two algorithms is analyzed in detail. With dynamic slice requests, simulations are performed to evaluate and compare their performance in terms of slice blocking probability and resource usage. Meanwhile, two different network scenarios are considered in simulation. Simulation results indicate that PDS-WI outperforms PDS-LI by accommodating more URLLC slices. © 2009-2012 OSA.
  •  
44.
  • Mas-Machuca, Carmen, et al. (författare)
  • Methodology for a cost evaluation of migration toward NGOA networks
  • 2013
  • Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 5:12, s. 1456-1466
  • Tidskriftsartikel (refereegranskat)abstract
    • Evolution of optical access networks promises to bring higher bandwidth to more customers. However, this evolution toward so-called next generation optical access (NGOA) networks also introduces additional challenges that operators and/or vendors have to address: how to properly estimate and compare different NGOA architectures and their evolutionary paths in terms of their economics. Calculating the total cost of ownership (TCO) for NGOA networks is a very complex target as it needs to involve good knowledge of the technology, the existing network infrastructure, and any migration-related processes. In this paper a complete methodology is presented for evaluating the TCO of the migration toward a NGOA network. It contains a detailed description of which key aspects have to be considered, which processes they affect, and how they are translated into costs in a logical manner. Finally, it also shows how this methodology has been applied to particular selected cases and how it gives a detailed view of all costs involved in migration. This approach opens up opportunities to cooperate in techno-economic research using it as a base. Both operators and vendors can also utilize this approach to get a useful economic background of their future investments and potential sales.
  •  
45.
  • Monti, Paolo, 1973-, et al. (författare)
  • Introduction to the Feature Issue on the IEEE Globecom 2017 ONS Symposium
  • 2018
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 10:8, s. ONS1-ONS2
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This feature issue is based on extended and revised versions of the top-ranked papers presented at the Optical Networks and Systems (ONS) Symposium that took place during the IEEE Global Communications Conference (GLOBECOM 2017). The papers appearing in this Feature Issue cover a wide range of topics, including elastic optical networks, mobile fronthaul, network function virtualization, survivability, and hybrid datacenter networks.
  •  
46.
  • Muhammad, Ajmal, et al. (författare)
  • Introducing Flexible and Synthetic Optical Networking : Planning and Operation Based on Network Function Programmable ROADMs
  • 2014
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0620 .- 1943-0639. ; 6:7, s. 635-648
  • Tidskriftsartikel (refereegranskat)abstract
    • Elastic optical networks are envisaged as promising solutions to fulfill the diverse bandwidth requirements for the emerging heterogeneous network applications. To support flexible allocation of spectrum resources the optical network nodes need to be agile. Among the different proposed solutions for elastic nodes, the one based on architecture of demand (AoD) exhibits considerable flexibility against the other alternatives. The node modules in the case of AoD are not hard-wired, but can be connected/disconnected to any input/output port according to the requirements. Thus, each AoD node and the network (fabricated with AoD nodes) as a whole acts like an optical field-programmable gate array. This flexibility inherent in AoD can be exploited for different purposes, such as for cost-efficient and energy-efficient design of the networks. This study looks into the cost-efficient network planning issue for synthetic networks implemented through AoD nodes. The problem is formalized as an integer linear programming formulation for presenting the optimal solution. Furthermore, a scalable and effective heuristic algorithm is proposed for cost-efficient design, and its performance is compared with the optimal solution. The designed networks with AoD nodes are further investigated for a dynamic scenario, and their blocking probability due to limited switching resources in the nodes is examined. To alleviate the blocking performance for the dynamic case, an efficient synthesis strategy along with a scheme for optimal placement of switching resources within the network nodes is presented. Extensive results show that 1) even at high loads, the network with AoD nodes achieves saving of switching modules up to 40% compared to the one with static reconfigurable optical add-drop multiplexers (ROADMs) through a proper network design, 2) by diminishing the spectrum selective switches the overall power consumption of the network decreases by more than 25% for high loads, and 3) for the dynamic scenario the blocking owing to the node modules constraint is alleviated significantly by slightly augmenting the switching devices and optimally deploying them within the network nodes.
  •  
47.
  • Muhammad, Ajmal, et al. (författare)
  • Manycast, Anycast, and Replica Placement in Optical Inter-Datacenter Networks
  • 2017
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:12, s. 1161-1171
  • Tidskriftsartikel (refereegranskat)abstract
    • The expanding adoption of cloud-based services in recent years puts stringent requirements on datacenters (DCs) and their interconnection networks. Optical inter-datacenter networks represent the only viable option for satisfying the huge bandwidth required to replicate and update content for cloud-based services across geographically dispersed datacenters. In addition to content replication and synchronization, optical inter-datacenter networks must also support communication between datacenters and end-users. The resulting new traffic patterns and the enormous traffic volumes call for new capacityefficient approaches for inter-datacenter network designs that incorporate both transport and datacenter resource planning. This paper introduces an integrated approach to optimally place content replicas across DCs by concurrently solving the routing and wavelength assignment (RWA) problem for both inter-DC content replication and synchronization traffic following the manycast routing paradigm, and end-user-driven user-to-DC communication following the anycast routing paradigm, with the objective to reduce the overall network capacity usage. To attain this goal, the manycast, anycast, and replica placement (MARP) problem is formulated as an integer linear program to find optimal solutions for smaller problem instances. Due to the problem complexity, a scalable and efficient heuristic algorithm is developed to solve larger network scenarios. Simulation results demonstrate that the proposed integrated MARP strategy can significantly reduce the network capacity usage when compared to the benchmarking replica placement and RWA schemes aimed at minimizing the resources consumed by either of the two types of traffic independently.
  •  
48.
  • Muhammad, Ajmal, et al. (författare)
  • Service Differentiated Provisioning in Dynamic WDM Networks Based on Set-Up Delay Tolerance
  • 2013
  • Ingår i: Journal of Optical Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 1943-0620 .- 1943-0639. ; 5:11, s. 1250-1261
  • Tidskriftsartikel (refereegranskat)abstract
    • Optical networks are expected to provide a unified platform for a diverse set of emerging applications (three-dimensional TV, digital cinema, e-health, grid computing, etc). The service differentiation will be an essential feature of these networks. Considering the fact that users have different levels of patience for different network applications, referred to as set-up delay tolerance, it will be one of the key parameters for service differentiation. Service differentiation based on set-up delay tolerance will not only enable network users to select an appropriate service class (SC) in compliance with their requirements, but will also provide an opportunity to optimize the network resource provisioning by exploiting this information, resulting in an improvement in the overall performance. Improvement in network performance can be further enhanced by exploiting the connection holding-time awareness. However, when multiple classes of service with different set-up delay tolerances are competing for network resources, the connection requests belonging to SCs with higher set-up delay tolerance have better chances to grab the resources and leave less room for the others, resulting in degradation in the blocking performance of less patient customers. This study proposes different scheduling strategies for promoting the requests belonging to smaller set-up delay tolerance SCs, such as giving priority, reserving some fraction of available resources, and augmenting the research space by providing some extra paths. Extensive simulation results show that 1) priority in the rescheduling queue is not always sufficient for eradicating the degradation effect of high delay tolerant SCs on the provisioning rate of the most stringent SC, and 2) by utilizing the proposed strategies, resource efficiency and overall network blocking performance improve significantly in all SCs.
  •  
49.
  • Nag, Avishek, et al. (författare)
  • Exploiting Dual Homing in Access Networks to Improve Resiliency in Core Networks
  • 2016
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 8:11, s. 854-862
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a network architecture consisting of long-reach passive optical network-based access and a transparent optical core network. The end users are connected to the remote node or the local exchange (LE) through an optical distribution network, and the remote node is connected by disjoint feeder fiber links to central offices located in two distinct metro/ core (MC) nodes. This method of connecting a single remote node to two geographically separate MC nodes for dedicated protection in case of feeder fiber failure is referred to as dual homing. In this work, we explore the benefits of dual homing in the access in simultaneously providing better resilience and load balancing in the core network considering connections between LEs. While looking into the benefits of dual homing in terms of network resiliency, we also explore whether the path redundancies added by dual homing play a role in providing efficient distribution of load across the core network and thereby reduce the cost of provisioning capacity in terms of number of lightpaths, transponders, etc. Dual homing at both the source and destination LEs offers more options for paths between LEs through the core network. Our results show that dual-homed access proves to be advantageous over single-homed access in terms of enhancing both core network resiliency and facilitating better load balancing.
  •  
50.
  • Natalino, Carlos, 1987-, et al. (författare)
  • Restoration in Optical Cloud Networks With Relocation and Services Differentiation
  • 2016
  • Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 8:2, s. 100-111
  • Tidskriftsartikel (refereegranskat)abstract
    • Optical cloud networks allow for the integrated management of both optical and IT resources. In this paradigm, cloud services can be provisioned in an anycast fashion; i.e., only the source node asking for a service is specified, while it is up to the cloud control/management system to select the most suitable destination data center (DC) node. During the cloud service provisioning process, resiliency is crucial in order to guarantee continuous network operations also in the presence of failures. On the one hand, a survivability strategy needs to be able to meet the availability requirements of each specific cloud service, while on the other hand it must be efficient in using backup resources. This paper proposes a restoration-based survivability strategy, which combines the benefits of both cloud service relocation and service differentiation concepts. The former is used to enhance the restorability performance (i.e., the percentage of successfully restored cloud services) offered by restoration, while the latter ensures that critical services are given the proper consideration while backup resources are assigned. The paper proposes both an integer linear programming (ILP) formulation, which guarantees optimal results, and a heuristic, which trades the optimality of the solution achieved by the ILP for faster processing times. Simulation results show that the average service availability and restorability performance obtained by both the ILP and the heuristic are very close to that achievable using a protection-based strategy, but with the inherent benefit, in terms of efficient use of resources, offered by a restoration-based approach.
  •  
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