1,721,032 research outputs found
Software-defined WDM optical transport in disaggregated open optical networks
No full textTransparent optical networks operated by WDM coherent optical technologies for data transport are moving-on towards the implementation of the openness paradigm. In such a context, disaggregated network elements and subsystems can be abstracted to manage and control propagation of WDM optical data transport. It enables the application of the software-defined paradigm down to the physical layer, with optical transport fully summarized by a quality of transmission estimator
Digital-Twin of Physical-Layer as Enabler for Open and Disaggregated Optical Networks
Full text linkThe physical layer in optical networks is a set of transparent optical circuits — light-paths (LP)s — that has been extensively shown as reliably approximated by additive white and Gaussian noise channels. Noise sources setting the LP generalized SNR (GSNR) are the ASE noise from amplifiers, the nonlinear interference (NLI) from the Kerr effect and crosstalk from ROADMs. Coherent transceivers can be effectively modeled by the back-to-back characterization by defining the GSNR thresholds. We will describe the physics behind such approximation including the statistical impairments due the PMD, PDL and filtering penalties, and other uncertainties. Then, we will show how the physical layer digital twin (PHY-DT) that integrates the transmission impairment models can be exploited to reliably evaluate the QoT, latency and energy consumption on the topology. Finally, we will comment on the possible use of the PHY-DT as vendor neutral planning tool for disaggregated infrastructure and as on-line service within the multi-layer hierarchical controller. The optical devices controller can be separated from the optical circuit deployment, so enabling multi-vendor networks. We will also comment on the synergistic use of AI&ML techniques assisting the PHY-DT
Introduction to the JOCN Special Issue on Open Optical Networks
Full text linkWe provide an introduction to the paradigm of open optical networks (OON), including its evolution and benefits, followed by a brief summary of the papers in the OON special issue
Band-Division vs. Space-Division Multiplexing: A Network Performance Statistical Assessment
Full text linkWe compare the networking merit of two possible multiplexing techniques on top of wavelength division multiplexing to enlarge transmission capacity: the band division multiplexing (BDM) that aims at using up to all the U-to-O low-loss transmission bands available on the G-652.D fiber and the spatial division multiplexing (SDM) implemented by activating additional fibers, used on the C-band only. We use the statistical network assessmemnt process (SNAP) to derive the networking performance as blocking probability vs. the total allocated traffic normalized with respect to the multiplexing cardinality. We analyze two network topologies: the German regional network and the US-NET continental network. In case dark fibers are available, SDM upgrades are always the best solution, enabling up to 12% and 17% of extra traffic at blocking probability equal to 10^{-3} on top of the multiplication by the multiplexing cardinality (N_{ ext{M}}) of 12, for the German and US-NET topology, respectively. BDM solutions present worse performance, but mixed BDM/SDM solutions display quite limited penalties with respect to the pure SDM solution, up to the use of 16 THz per fiber. So, mixed BDM/SDM implementation seems the most convenient solution in case of limited availability of dark fibers. Pure BDM solutions occupying a bandwidth larger than 16 THz display an increasingly and considerable gap in the allocated traffic with respect to the pure BDM, therefore, their use must be considered only in case of total absence of available dark fibers
Multi-Band and Multi-Service Open Optical Networks: Applications and Perspectives
No full textWorldwide, most of the countries are fast moving towards the deployment of pervasive optical network infrastructures based on fiber optics transmission. First, to support core data-networks, then progressively towards metro and access networks to support 5G, as well as cloud services, data-center interconnects and content delivery networks. Network operators are progressively requiring the implementation of the openness paradigm to better exploit the infrastructures down to the optical transport, and to develop and control the deployed services. We address the physics of propagation of optical signals over a transparent optical infrastructure and show how the optical transmission can be abstracted. We comment on the control and management of multiband optical network arguing on the capability for operators to implement network slicing for different services. We address the use of optical infrastructures for non-data services - e.g., Time and frequency distribution or sensing signals - either on dedicated fibers, or on dedicated bands or spectral portions, in general
A Networking Comparison between Multicore Fiber and Fiber Ribbon in WDM-SDM Optical Networks
No full textSpatial division multiplexing (SDM) represents a possible solution to face the continuous traffic growth. We compare: uncoupled fiber ribbons and strongly coupled-core multicore fibers. We compare them analyzing propagation and switching issues varying the SDM cardinality
Synergetical use of analytical models and machine-learning for data transport abstraction in open optical networks
Full text linkThe key-operation to enabling an effective data transport abstraction in open optical line systems (OLS) is the capability to predict the quality of transmission (QoT), that is given by the generalized signal-to-noise ratio (GSNR), including both the effects of the ASE noise and the nonlinear interference (NLI) accumulation. Among the two impairing effects, the estimation of the ASE noise is the most challenging task, because of the spectrally resolved working point of the erbium-doped fiber amplifiers (EDFA) depending on the spectral load, given the overall gain. While, the computation of the NLI is well addressed by mathematical models based on the knowledge of parameters and spectral load of fiber spans. So, the NLI prediction is mainly impaired by the uncertainties on insertion losses an spectral tilting. An accurate and spectrally resolved GSNR estimation enables to optimize the power control and to reliably and automatically deploy lightpaths with minimum margin, consequently maximizing the transmission capacity. We address the potentialities of machine-learning (ML) methods combined with analytic models for the NLI computation to improve the accuracy in the QoT estimation. We also analyze an experimental data-set showing the main uncertainties and addressing the use of ML to predict their effect on the QoT estimation
Networking benefit of multi-subcarrier transceivers
No full textWe analyze the benefit of multi-subcarrier transceivers on two network topologies. We describe nonlinearities modeling challenges and demonstrate the existence of an optimal subcarrier symbol rate at network-level yielding average OSNR increase up to 0.7dB
Statistical assessment of open optical networks
Full text linkIn order to cope with the increase of the final user traffic, operators and vendors are pushing towards physical layer aware networking as a way to maximize the network capacity. To this aim, optical networks are becoming more and more open by exposing physical parameters enabling fast and reliable estimation of the lightpath quality of transmission. This comes in handy not only from the point of view of the planning and managing of the optical paths but also on a more general picture of the whole optical network performance. In this work, the Statistical Network Assessment Process (SNAP) is presented. SNAP is an algorithm allowing for estimating different network metrics such as blocking probability or link saturation, by generating traffic requests on a graph abstraction of the physical layer. Being aware of the physical layer parameters and transceiver technologies enables assessing their impact on high level network figures of merit. Together with a detailed description of the algorithm, we present a comprehensive review of several results on the networking impact of multirate transceivers, flex-grid spectral allocation as a means to finely exploit lightpath capacity and of different Space Division Multiplexing (SDM) solutions
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