Impairments Monitoring Technique Based on Overmodulation for Elastic Optical Networks

Optical networks are undergoing significant changes, fueled by the exponential growth of traffic due to multimedia services and by the increased uncertainty in predicting the sources of this traffic due to the ever changing models of content providers over the Internet. The change has already begun: simple on-off modulation of signals, which was adequate for bit rates up to 10 Gb/s, has given way to much more sophisticated modulation schemes for 100 Gb/s and beyond. The next bottleneck is the 10-year-old division of the optical spectrum into a fixed “wavelength grid,” which will no longer work for 400 Gb/s and above, heralding the need for a more flexible grid. Once both transceivers and switches become flexible, a whole new elastic optical networking paradigm is born. This new networking technology provides an opportunity to maximize spectral efficiency for each of many arbitrary bandwidth channels generated using one of many possible modulation formats. However, optical signals with high spectral efficiency are highly sensitive to physical layer impairments (PLIs), which accumulate differently depending on network configurations. In particular, bit error rates can rise due to changes in environmental conditions or degradations in optical signal-to-noise ratios (OSNR) of the affected optical links. The flexible bandwidth networking technique together with an effective optical performance monitoring method and an adaptive control plane can offer adaptive optimization of the network based on impairments (impairment-aware networking). By adopting a practical and real-time performance monitoring method that spans a broad and elastic spectral width, the network can dynamically and adaptively adjust the modulation format to maximize spectral efficiency while maintaining the required quality of service (QoS) and bit error rate (BER) performance even for signals experience time-varying PLIs. In this thesis we first simulate and then experimentally demonstrate an impairment monitoring technique based on a low-frequency and low-modulation-index intensity modulation applied to the high-bandwidth data signals (10Gb/s and above). Using premeasured correlation data between the Bit Error Rate of the monitor signal and the data signal, the proposed monitoring technique allows to detect the quality of the link and to determine if the data signal is affected from linear impairments (i.e.. optical noise accumulation, in-band crosstalk) and nonlinear impairments such as Four-Wave-Mixing. First, we carried out an extensive simulation study to verify the effectiveness of the proposed technique and determine the best design parameters such as line rate of the monitor signal and overmodulation index. This study was carried out for different modulation formats, i.e. OOK, QPSK, and 16QAM, considering both linear and non-linear impairments. Second, we verified, through an experimental study, some of the results obtained through simulation for the OOK case, demonstrating (a) the need of line coding techniques such as 8B/10B and/or 9B/10B to properly detect the monitor signal when the line signal is intensity modulated; (b) the correlation between the BER of an OOK line signal at 10-Gb/s and the BER of the overmodulating signal at 20Mb/s, in the case where the system is affected by a linear impairment such as optical noise accumulation

Covid-19 Pandemic and the Fiscal Strategy of the International Monetary Fund: Towards New Directions in the Global Political Economy?

This article seeks to contribute to the analyses of the impact of the Covid-19 on the global political economy. It does so through a qualitative content analysis of the key policy documents published by the International Monetary Fund (IMF) since the outbreak of the pandemic crisis. The IMF has been, historically, one of the main designers of international macroeconomic governance. The paper focuses on fiscal policy, which retains a central place in the strategy of the IMF to deal with the pandemic and especially for the post-pandemic recovery phase. The analysis of the documents of the IMF contributes (i) to appreciate the interpretation of the nature of the pandemic crisis through the lenses of a prominent international financial institution, (ii) to explore the policy strategy outlined to deal with the pandemic emergency, (iii) to assess possible changes at the level of policy, and accordingly, future directions in global political economy. Evidence suggests that fiscal stimulus, public investment and planning will likely have a prominent position in the future directions of the IMF policy advice

Virtualized eNB Latency Limits

In flexible functional split, functions of a virtualized evolved NodeB (eNB) can be disaggregated in distributed computational resources. One of the main constraints for their placement is the latency experienced by the communication between the Virtual Machines (VM) hosting the functions. This paper evaluates experimentally the latency limits for different functional splits providing insights on flexible functional split implementationThis work has been partially funded by the EU H2020 5G-Transformer Project (grant no. 761536

Fisheye Photogrammetry to Survey Narrow Spaces in Architecture and a Hypogea Environment

Nowadays, the increasing computation power of commercial grade processors has actively led to a vast spreading of image-based reconstruction software as well as its application in different disciplines. As a result, new frontiers regarding the use of photogrammetry in a vast range of investigation activities are being explored. This paper investigates the implementation of fisheye lenses in non-classical survey activities along with the related problematics. Fisheye lenses are outstanding because of their large field of view. This characteristic alone can be a game changer in reducing the amount of data required, thus speeding up the photogrammetric process when needed. Although they come at a cost, field of view (FOV), speed and manoeuvrability are key to the success of those optics as shown by two of the presented case studies: the survey of a very narrow spiral staircase located in the Duomo di Milano and the survey of a very narrow hypogea structure in Rome. A third case study, which deals with low-cost sensors, shows the metric evaluation of a commercial spherical camera equipped with fisheye lenses

Impact of CoMP VNF Placement on 5G Coordinated Scheduling Performance

To address demanding requirements in terms of expected throughput, latency and scalability, 5G networks will offer high capacity to support huge volumes of traffic generated by heterogeneous services. Dense deployment of small cells can provide a valid solution but are prone to high levels of interference especially at the cell-edge. However, to reduce inter-cell interference and improve cell-edge throughput, a set of techniques known as Coordinated Multipoint (CoMP) has been introduced. Coordinated Scheduling (CS) is a CoMP technique that assigns resources to mobile users to avoid interference between users that are assigned within the same Physical Resource Blocks (PRBs). On the other hand, Software Defined Mobile Networking (SDMN) and Network Function Virtualization (NFV) represent two key technologies to enhance flexibility and efficiency of resource usage within the Radio Access Network (RAN). However, the implementation of CoMP CS techniques on NFV architecture in a dense small cell scenario have not been analyzed yet. In this paper, we propose the joint use of CoMP CS and NFV by studying the implications of different deployment strategies, as constrained by the physical topology of the underlying RAN. The performance of both distributed and centralized CoMP CS are compared in terms of convergence delay and traffic overhead. Guidelines for the optimal design are provided.This work was partially supported by the Italian Government under CIPE resolution no. 135 (December 21, 2012), project INnovating City Planning through Information and Communication Technologies (INCIPICT) and by the EC through the H2020 5G-TRANSFORMER project (Project ID 761536)

Impact of RAN Virtualization on Fronthaul Latency Budget: An Experimental Evaluation

In 3GPP the architecture of a New Radio Access Network (New RAN) has been defined where the evolved NodeB (eNB) functions can be split between a Distributed Unit (DU) and Central Unit (CU). Furthermore, in the virtual RAN (VRAN) approach, such functions can be virtualized (e.g., in simple terms, deployed in virtual machines). Based on the split type, different performance in terms of capacity and latency are requested to the network (i.e., fronthaul) connecting DU and CU. This study experimentally evaluates, in the 5G segment of the Advanced Research on NetwOrking (ARNO) testbed (ARNO-5G), the fronthaul latency requirements specified by Standard Developing Organizations (SDO) (3GPP in this specific case). Moreover it evaluates how much virtualization impacts the fronthaul latency budget for the the Option 7-1 functional split. The obtained results show that, in the considered Option 7-1 functional split, the fronthaul latency requirements are about 250 μs but they depend on the radio channel bandwidth and the number of the connected UEs. Finally virtualization further decreases the latency budget.This work has been partially funded by the EU H2020 5GTransformer Project (grant no. 761536

an application of cosmo sky med to coastal erosion studies

AbstractStarted in 2009, the COSMOCoast project aims to the investigation of the potential of Remote Sensing in support to the management of coastal areas. Particular attention is paid to the contribution of data acquired from the COSMO-SkyMed constellation, in view of their frequency of acquisitions and ground resolution; in particular this paper aims at assessing the potential of COSMO-SkyMed data for coastline delineation. The results are conceived to be of particular interest for public administration bodies in charge of coastal defense. Keywords: Remote Sensing, Coastal Zones Management, COSMO-SkyMed

Can we trust in Sars-CoV-2 rapid antigen testing? Preliminary results from a paediatric cohort in the emergency department

BACKGROUND: Rapid identification of Covid-19 in the paediatric emergency department is critical; Antigen tests are fast but poorly investigated in children. AIMS: To investigate Sars-CoV-2 antigen rapid test in children. METHODS: We compare the performance of LumiraDx with molecular tests in a paediatric emergency department. RESULTS: A retrospective cohort of 191 patients with AT and PCR tests performed in the same episode was analysed; 16% resulted positive for Sars-CoV-2. Using the PCR test as the gold standard, we calculated antigen testing overall sensitivity of 94.1%, specificity of 91.9%, and NPV of 99.4%. Only one false-negative test was found. CONCLUSIONS: AT may be helpful in the initial screening of patients at PED

Low Adherence To Nutritional Recommendations In Patients With Cirrhosis: A Prospective Observational Study

n/