Salvatore Spadaro

Universitat Politècnica de Catalunya | UPC · Department of Signal Theory and Communications (TSC)

In multilayer IP over optical networks, the optical layer provides the lightpaths to transmit aggregated time-varying requests from the packet layer. By exploiting the traffic grooming, enabled by the cross-layer information exchange, the number of lightpaths to be established can be minimized by using spare capacity available on them grooming new...

Metro-access networks will play a primary role in future network fabrics, enabling connectivity among different actors such as 5G-based radio stations, edge datacenters, businesses, and home users. To provide such heterogeneous connectivity, changes to the current metro-access networks to provide them with greater scalability, higher levels of dyna...

Superchannels leverage the flexibility of elastic optical networks and pave the way to higher capacity channels in space division multiplexing (SDM) networks. A superchannel consists of subchannels to which continuous spectral grid slots are assigned. To guarantee superchannel operation, we need to account for soft failures, e.g., laser drifts caus...

The constantly increasing traffic volume triggers the fast development of new optimization methods for backbone optical networks. Operators seek new ways to improve several network performance metrics, including network stability. In this paper, we propose a multilayer packet-over-optical approach combining grooming and traffic prediction. We demon...

We demonstrate that joint orchestration of TSN and optical network domains in support of IIoT applications reduces the TSN blocking by four orders of magnitude and the usage of high priority queues by a 28-100%.

Due to the limitations of traditional data center (DC) architectures, the concept of infrastructure disaggregation has been proposed. DC resources are separated into multiple blades to be exploited independently. As a result, composable DC (CDC) infrastructures are achieved, enhancing the modularity of resource provisioning. However, disaggregation...

The rise of traffic intensive services and applications is pushing the limits of conventional single band Wavelength Division Multiplexing (WDM) optical networks. As an answer to this challenge, new data plane technologies are being investigated. Multi-band optical networks have raised as a very interesting candidate due to the potential increased...

In this paper, we present a worst-case methodology for estimating the attainable spectral efficiency over end-to-end paths across a Flex Grid over multicore fiber (MCF) optical network. This methodology accounts for physical link noise, as well as for the signal-to-noise ratio in the Add module ( S N R T X ) of spatial-division-multiplexing-enabled...

We propose a novel SDN control and orchestration architecture to provide composed IaaS over optical disaggregated data centers. We experimentally validate intent-based mechanisms that make the architecture independent from the underlying physical infrastructure technology.

Service quality assurance is of capital importance in modern cloud and network infrastructures, especially in multi-domain scenarios, where multiple operators collaborate to provide end-to-end (E2E) services. However, due to the dynamics of the multiple infrastructures and deployed services, it may be difficult to identify which domains need to per...

In order to compete for a prominent market share, network operators and service providers should retain and increase the verticals’ subscription, catering to their needs in order to differentiate themselves from competitors. In this scenario, verticals’ satisfaction arises of paramount importance. As such, user experience is becoming a reliable ind...

Leaving the current 4th generation of mobile communications behind, 5G will represent a disruptive paradigm shift integrating 5G Radio Access Networks (RANs), ultra-high-capacity access/metro/core optical networks, and intra-datacentre (DC) network and computational resources into a single converged 5G network infrastructure. The present paper over...

For reliable and efficient network planning and operation, accurate estimation of Quality of Transmission (QoT) is necessary. In optical networks, a physical layer model (PLM) is typically used as a QoT estimation tool (Qtool) including a design margin to account for modeling and parameter inaccuracies, to ensure acceptable performance. Such margin...

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 n...

Having ubiquitous optical monitors in dense wavelength-division multiplexing (DWDM) or flex-grid networks allows the estimation in real time of crucial parameters. Such monitoring would be even more important in disaggregated optical networks, to inspect performance issues related to inter-vendor interoperability. Several important parameters can b...

Optical network optimization involves an algorithm and a physical layer model (PLM) to estimate the quality of transmission of connections while examining candidate optimization operations. In particular, the algorithm typically calculates intermediate solutions until it reaches the optimum, which is then configured to the network. If it uses a PLM...

We dynamically optimize the transponders launch powers with iterative closed control loops. We close the loop after an adaptable number of algorithm’s intermediate calculations, to monitor and retrain the QoT estimator with the real world.

We present an architectural solution based on data analytics for self-organizing optical data centers. Thanks to a reinforcement learning-based cognitive layer, an adaptive and autonomous resource assignment to deployed services is achieved.

Network Slicing appears as one of the enabling technologies for 5G networks to accommodate services with different requirements and availability. The present work seizes the use of network slicing and focuses on the deployment and maintenance of services which are sensitive to latency constraints. For this purpose, the design and use of a VNF laten...

Network architectural changes to satisfy all the 5G+ mobile network specifications and requirements are necessary due to the popularization of streaming and cloud applications on omnipresent portable devices. The combination of massive installation of micro-cell antenna sites with the cloud access radio network (C-RAN) architecture has recently bee...

In this paper, we focus on the design of different node architectures suitable for Few-Mode Multi-Core Fibers (FM-MCFs) based networks. Both dimensions, core and mode, open different possible ways to group spatial channels depending on the physical impairments of the Space-Division Multiplexed (SDM) optical fibers. Moreover, the channel switching a...

Today's optical transport networks are complex already and the support of the new arising services will further increase such complexity. Traditional deterministic network procedures will need to be revisited, especially their operations. Network Operators will require more dynamic approaches to get the best out of their infrastructure. In this con...

In this paper, we motivate a brown-field migration planning as a cost-efficient procedure to scale the capacity of short-term realizable elastic optical networks (EONs), gradually converting them into spectrally-spatially flexible optical networks (SS-FONs). After a formal statement of the brown-field EON to SS-FON migration planning problem, a Sto...

The ever-growing data traffic volume inside data centers caused by the popularization of cloud services and edge computing demands scalable and cost-efficient network infrastructures. With this premise, optical interconnects have recently gained more and more research attention as a key building block to ensure end-to-end energy efficient solutions...

We report experimental results of a semiconductor optical amplifier (SOA) for optical amplification in a 50-90 Gb/s IM-DD optical access system using non-orthogonal multiple access multiplexing combined with multi-band carrierless amplitude phase modulation format (NOMA-CAP). Specifically, the SOA has been investigated as both booster and pre-ampli...

The current deployment of 5G networks in a way to support the highly demanding service types defined for 5G, has brought the need for using new techniques to accommodate legacy networks to such requirements. Network Slicing in turn, enables sharing the same underlying physical infrastructure among services with different requirements, thus providin...

For reliable and efficient network planning and operation, accurate estimation of Quality of Transmission (QoT) before establishing or reconfiguring the connection is necessary. In optical networks, a design margin is generally included in a QoT estimation tool (Qtool) to account for modeling and parameter inaccuracies, ensuring the acceptable perf...

Network slicing has been taking a major role in upcoming 5G network implementations. However, in order to provision and maintain end-to-end slices, the management and orchestration among different network segments is required. As a result, techniques and components have risen to fulfil these tasks. In this work, we present latency-aware slicing, wh...

Optical switching techniques have the potential to enable the optical data center network (DCN) interconnections providing high capacity and fast switching capabilities, overcoming thus the bandwidth and latency bottleneck of present electrical switch-based multi-tiered DCNs. The rapid growth of multi-tenant applications with heterogeneous traffic...

Monitoring 3dB bandwidth and other spectrum related parameters at ROADMs provides information about quality of their filters. We propose a machine-learning model to estimate end-to-end filtering penalty for more accurate QoT estimation of future connections.

Disaggregated DCs offer multiple benefits. However, transmission capacity limitations at blade level can severely degrade their performance. We analyze several strategies to enhance their service acceptance.

Measuring the optical signal to noise ratio (OSNR) at certain network points is essential for failure handling, for single connection but also global network optimization. Estimating OSNR is inherently difficult in dense wavelength routed networks, where connections accumulate noise over different paths and tight filters do not allow the observatio...

This article identifies the unavoidably required upgrade of short-term realizable elastic optical networks (EONs) operating over single-mode fibers toward spectrally-spatially flexible optical networks (SS-FONs), exploiting spatial division multiplexing (SDM) technology in order to cope with the expected mid- and long-term future traffic forecasts....

We investigate the blocking performance of a dynamic, spectrally and spatially flexible optical network (SS-FON) in which spectral super-channels (SChs) utilizing multiple modulation formats (MFs) are carried over weakly-coupled multi-core fibers (MCFs) and the amount of transceivers (TRX) in network nodes is limited. In the SS-FON scenario conside...

The emergence of new paradigms and services is pushing the limits of nowadays cloud infrastructures. It is a fact that current solutions lack in the flexibility and configurability to adapt to heterogeneous requirements coming from the applications/services to be supported over them. This results most of the time in severe underutilization of the u...

Media use cases for emergency services require mission-critical levels of reliability for the delivery of media-rich services, such as video streaming. With the upcoming deployment of the fifth generation (5G) networks, a wide variety of applications and services with heterogeneous performance requirements are expected to be supported, and any migr...

The current constant growth in mobile networks' traffic demands caused by the popularisation of cloud and streaming services on personal devices, requires architectural changes so as to fulfil all new 5G mobile network requirements. Cloud access radio network (C-RAN) architecture in combination with the massive deployment of small cell antenna site...

We study inter-core crosstalk (ICXT) impact on migration planning toward spectrally-spatially flexible optical networks considering 22-core multi-core fiber. Results reveal, 55-70% of links need to be upgraded when ICXT ranges from -68.2 to-43.4 dB/km.

The use of optical technologies in modern network scenarios has increased in the last decade, mostly due to their support in crucial networking topics (ie, bandwidth and scalability). In parallel, these scenarios have also experienced the emergence of a new paradigm recognized as software‐defined networking (SDN), which bases on the decoupling of f...

We propose and evaluate a dynamic traffic grooming strategy enhancing the performance of JoS-enabled Flex-Grid/SDM networks. Results disclose up to 120% and 44% additional carried network traffic vs. no grooming and existing end-to-end traffic grooming solutions, respectively.

We focus on a migration planning from elastic to spectrally-spatially flexible optical networks by upgrading regular with SDM-capable ROADMs. Our most promising strategy reveals that by migrating 30% of the regular ROADMs a 2x carried traffic increase can be achieved.

The sensitivity performance of an IMDD-OFDM/FBMC/UFMC/GFDM system with a PIN based receiver is experimentally evaluated for downstream in broadband passive optical networks. Results show sensitivities better than-14.5(-8.0)dBm over 50km of SSMF at 5(10)Gbps

The current constant growing in traffic demands caused by the popularization of cloud services, mobile and social networks is requiring architectural changes at the underlying networks so as to provide a more highly dynamic connectivity. Cost-effective and energy efficient solutions are also required in flexible network subsystems in order to make...

In this paper, we target an optimal Multiple-Input Multiple-Output Digital Signal Processing (MIMO-DSP) assignment to super-channels affected by inter-core crosstalk (ICXT) in Multi-Core Fiber (MCF)-enabled transparent optical core networks. MIMO-DSP undoes ICXT effects, but can be costly with high core density MCFs. Hence, its implementation in th...

Future optical core networks realizing Flex-Grid and Space Division Multiplexing (Flex-Grid/SDM) will be key to effectively cope with the rapid growth of the Internet traffic, thanks to their superior capacity and spectrum utilization flexibility. Specifically about SDM, the spatial dimension can be considered either fixed or flexible. The goal of...

Network slicing has emerged as a major new networking paradigm for meeting the diverse requirements of various vertical businesses in virtualised and softwarised 5G networks. SliceNet is a project of the EU 5G Infrastructure Public Private Partnership (5G PPP) and focuses on network slicing as a cornerstone technology in 5G networks, and addresses...

Space Division Multiplexing (SDM) appears as a promising solution to overcome the capacity limits of single-mode optical fibers. In Flex-Grid/SDM optical networks, nodes offering full interconnection between input/output fiber ports and spatial channels, typical SDM-Reconfigurable Optical Add/Drop Multiplexer (SDM-ROADM) referred to as independent...

Architectural changes are required for the underlying networks to support the expected Internet data traffic volume growth caused by the popularization of cloud services, 5G-based services, and social networks, to provide a highly dynamic connectivity. Cost-effective and energy-efficient solutions for flexible network subsystems are required to pro...

Space Division Multiplexing (SDM) is a key technology to cope with the bandwidth limitations of single mode fibers. Multi-Core Fibers (MCFs) are considered as a promising candidate technology to implement SDM, due to their low inter-core crosstalk (ICXT), experimentally proven in laboratory prototypes. Among the different channel allocation options...

The Internet data traffic constant growth caused by the popularization of cloud services, mobile and social networks is requiring changes at the underlying networks in order to enable scalability whereas supporting a highly dynamic connectivity. Cost-effective and energy efficient solutions for flexible network subsystems are also required in order...

Virtual Data Centre (VDC) allocation requires the provisioning of both computing and network resources. Their joint provisioning allows for an optimal utilization of the physical Data Centre (DC) infrastructure resources. However, traditional DCs can suffer from computing resource underutilization due to the rigid capacity configurations of the ser...

The majority of the research studies on Flex-Grid over multi-core fiber (Flex-Grid/MCF) networks are built on the assumption of fully non-blocking ROADMs (FNB-ROADMs), able to switch any portion of the spectrum from any input core of any input fiber to any output core of any output fiber. Such flexibility comes at an enormous extra hardware cost. I...