Showing papers presented at "International Conference on Transparent Optical Networks in 2019"

Transmitter Diversity with Beam Steering

Abstract: Providing high data rates is one of the drivers in visible light communication (VLC) systems. This paper introduces a VLC system that employs angle diversity transmitters with beam steering to provide high data rates. In this work, red, yellow, green, and blue (RYGB) laser diodes (LD) are used as transmitters to obtain a high modulation bandwidth. Two types of RYGB LDs units are used in this paper: angle diversity transmitters (ADT) RYGB LDs light unit (for illumination and communication) and RYGB LDs light unit (for illumination). In addition, a four branch angle diversity receiver (ADR) is used where we study the delay spread and SNR. The proposed system was compared to the normal VLC system. A data rate up to 22.8 Gb/s was achieved using simple on-off-keying (OOK) modulation.

Optimized Resource Allocation in Multi-User WDM VLC Systems

Abstract: In this paper, we address the optimization of wavelength resource allocation in multi-user WDM Visible Light Communication (VLC) systems. A Mixed Integer Linear Programming (MILP) model that maximizes the sum of Signal-to-Interference-plus-Noise-Ratio (SINR) for all users is utilized. The results show that optimizing the wavelength allocation in multi-user WDM VLC systems can reduce the impact of the interference and improve the system throughput in terms of the sum of data rates for up to 7 users.

Visible Light Optical Data Centre Links

Abstract: Providing high data rates is one of the big concerns in visible light communication (VLC) systems. This paper introduces a data centre design that use a VLC system for downlink communication. In this work, RYGB laser diodes (LD) are used as transmitters to obtain a high modulation bandwidth. Three types of receivers, wide field of view receiver (WFOVR), 3 branches angle diversity receiver (ADR) and 50 pixels imaging receiver (ImR) are used to examine delay spread and SNR. The proposed system achieved data rates up to 14.2 Gbps using simple on-off-keying (OOK) modulation.

Upgrade Capacity Scenarios Enabled by Multi-band Optical Systems

Abstract: The ITU-G.652D is the most deployed optical fiber worldwide and presents a wide low-loss window with negligible water absorption peak. Multi-band systems exploit this characteristic to increase the transmission capacity. In this work, we show the optical degradation in terms of generalized signal-to-noise ratio, on different bands, resulting from successive channel upgrades until the complete low-loss window is occupied.

Machine Learning Aided Network Slicing

Abstract: Future 5G wireless networks will need to deal with increasing heterogeneity in offered services, performance requirements, and communication technologies. Network slicing has appeared as a technique to deal with the complex management of these future networks. Particularly, in wireless networks, link bitrate depends on several factors (e.g., interference). In a wire-wireless network scenario, any mechanism that proposes to manage and allocate resources to implement slicing in wireless devices will require knowledge of the channel characteristics. In this paper, we present a Deep Learning algorithm to predict if a service provider will be able to fulfil a new network slice request given the conditions of the channel and the allocated resources. As part of the Deep Learning algorithm architecture, given the sequentially of the transmission data, we designed and implemented a Long Short Memory Term network for predicting the channel conditions in the near future. Results show that the propose Deep Learning algorithm reduce the number of false positive allocations by a 75%.

Machine Learning for Ultrawide Bandwidth Amplifier Configuration

Abstract: Ultrawide bandwidth optical amplifier designs based on multiple pump wavelengths additionally benefit from gain control per sub-bands, at the cost of an increased configuration complexity. In such systems it becomes possible to adapt system parameters such as spectral tilt and optical output power per amplifier, in response to changing conditions in the network, such as wavelength re-configuration and repairs. Machine learning gives a high accuracy performance in configuring and monitoring amplifiers easing the complexity incurred by human-effort.

Dedicated Path Protection for Reliable Network Slice Embedding Based on Functional Splitting

Abstract: In the 5G context, new services can be designed based on service slice embedding on the network infrastructure in relation to target performance. With reference to the functional splitting approach known as xhaul, novel slicing deployment strategies for 5G are presented to provide resiliency while optimizing the use of optical and computational resources, having in mind the uRLLC service class.

Quantum Aware SDN Nodes in the Madrid Quantum Network

Abstract: QKD technology is mature enough to be used beyond the usual single, point to point, link by creating networks. Quantum ad hoc networks, where a separate, quantum-only network, is running in parallel to a classical network have been demonstrated in several occasions. Having to, essentially, duplicate the network to introduce quantum communications is very expensive and, beyond niche use-cases, fully integrated quantum-classical networks is what the industry demands to accept quantum technologies as a serious networking technology, ready for a broad market uptake.Recently we have reported on the successful deployment of the Madrid Quantum Network. This network is novel because it has been the first installed in production sites of a Telecommunications operator and moreover it is managed through a Software Defined Networking (SDN) structure that integrates classical and quantum channels. The network was operating for four months and we could demonstrate several technologies utilizing the integration of quantum and classical networks. Here we report on some implementation aspects and its usage in several use cases, in particular to secure the management of the SDN control plane as a critical infrastructure.

Energy Efficient Resource Allocation in Vehicular Cloud Based Architecture

Abstract: The increasing availability of on-board processing units in vehicles has led to a new promising mobile edge computing (MEC) concept which integrates desirable features of clouds and VANETs under the concept of vehicular clouds (VC). In this paper we propose an architecture that integrates VC with metro fog nodes and the central cloud to ensure service continuity. We tackle the problem of energy efficient resource allocation in this architecture by developing a Mixed Integer Linear Programming (MILP) model to minimize power consumption by optimizing the assignment of different tasks to the available resources in this architecture. We study service provisioning considering different assignment strategies under varying application demands and analyze the impact of these strategies on the utilization of the VC resources and therefore, the overall power consumption. The results show that traffic demands have a higher impact on the power consumption, compared to the impact of the processing demands. Integrating metro fog nodes and vehicle edge nodes in the cloud-based architecture can save power, with an average power saving up to 54%. The power savings can increase by 12% by distributing the task assignment among multiple vehicles in the VC level, compared to assigning the whole task to a single processing node.

Analog Radio Over Fiber Fronthaul for High Bandwidth 5G Millimeter-Wave Carrier Aggregated OFDM

Abstract: The increasing demands for high capacity and ultra-low latency services require to introduce a 5G mobile communications infrastructure based on a centralized radio access network with space division multiplexed optical fronthaul using radio-over-fiber. The transmission of carrier aggregated 5G OFDM signals over an analog radio-over-fiber fronthaul link is experimentally demonstrated. Multi-Gbit/s data rates are achieved in limited bandwidth, with BER below the 25% overhead FEC limit after millimeter-wave wireless transmission over 2.2 m.

Impact of Weather Conditions and Interference on the Performance of VLC based V2V Communication

Abstract: This works analyses the performance of Visible Light Communication (VLC) based Vehicular-to-Vehicular (V2V) Communication under different weather conditions viz. dense fog, light fog, wet snow, dry snow, rain etc. while considering the effect of interference from nearby vehicle. The performance has been evaluated by obtaining both quantitative as well as qualitative results. Through the obtained results, it has been shown that different weather conditions significantly impact the performance of VLC based V2V as compared to normal atmospheric conditions. It can be also inferred that interference from nearby vehicle and unfavourable weather conditions adversely impacts the Signal-to-Interference plus Noise ratio (SINR) for the VLC link which consequently reduces the maximum achievable communication-distance between the vehicles.

A Survey of Neural Network Applications in Fiber Nonlinearity Mitigation

Abstract: Advance in optical transmission towards higher bit rate and denser spectral efficiency is challenged by nonlinear effects. The existing digital signal processing techniques to compensate nonlinear fiber transmission impairments suffer from heavy computations and require the knowledge of a large number of system parameters, which is impractical in field environment. Neural networks are among the investigated solutions in literature to cope with the complexity of those models. Taking advantage of the huge amount of data available in optical transport networks, WDM systems represent a fertile field to apply neural networks.This paper is a non-exhaustive survey on neural network applications for nonlinear impairments mitigation in optical fiber transmission systems. We distinguish two approaches. The first one is dependent of the NonLinear Schrodinger Equation (NLSE) while the second one is based on machine learning techniques. These two approaches achieve similar performance compared to the well-known nonlinear mitigation methods with reduced computational complexity.

NIW: A Net2Plan-Based Library for NFV over IP over WDM Networks

Abstract: Software-Defined Networking (SDN) and Network Function Virtualization (NFV) technologies enable a major technological breakthrough for telecom operators’ networks. In this paper, we present the NFV over IP over WDM (NIW) library, an open-source framework for SDN/NFV metropolitan networks, created in the context of the Metro-Haul project. NIW is a library added to the Net2Plan open-source network planning software, specifically to model, provision, design and evaluate SDN/NFV networks. We introduce the major components and functionalities of NIW in a tutorial manner, including an Excel file loader meant to ease data loading for its manipulation through NIW data structure and its available methods. Finally, an illustrative example shows the basic library usage taking into account NFV over IP over WDM network resources in a reference topology.

Energy Efficient and Resilient Infrastructure for Fog Computing Health Monitoring Applications

Abstract: In this paper, we propose a resilient energy efficient and fog computing infrastructure for health monitoring applications. We design the infrastructure to be resilient against server failures under two scenarios; without geographical constraints and with geographical constraints. We consider a heart monitoring application where patients send their 30-seconds recording of Electrocardiogram (ECG) signal for processing, analysis and decision making at both primary and backup servers. A Mixed Integer Linear Programming (MILP) model is used to optimize the number and locations of the primary and backup processing servers so that the energy consumption of both the processing and networking equipment are minimized. The results show that considering geographical constraints yields a network energy consumption increase by up to 9% compared to without geographical constraint. The results also show that, increasing the number of processing servers that can be served at each candidate node can reduce the energy consumption of networking equipment besides reducing the rate of energy increase of networking equipment due to increasing level of demand.

Machine Learning for Regenerator Placement Based on the Features of the Optical Network

Abstract: With network traffic projected to increase drastically over the new few years, Elastic Optical Networks (EONs) have been brought in to be the successor of the currently used optical technologies. Many factors must be taken into consideration when deploying EONs for wide-scale use. One of which is the overall network’s resource allocation. A simple, uniform distribution of regenerators is too inefficient as different locations have different regenerator requirements based on the amount of network traffic they receive. On the other hand, increasing the number of installed regenerators after initial deployment will incur a substantial cost. The ideal scenario is to accurately predict the number of regenerators that each location will need.One way to provide accurate predictions for regenerator allocation is through the use of machine learning. In order to maximize the accuracy of the prediction provided by the machine learning algorithm, it must be supplied with quality input training data. In this paper, we examine the impact that different network features can have on prediction results. We then propose a list of network features that hold significant impact in regards to predicting regenerator allocation accurately.

Joint VNF-Provisioning and Virtual Topology Design in 5G Optical Metro Networks

Abstract: 5G technology will provide networks with high-bandwidth, low latency and multitenancy. The integration of computing and storage resources in the edge of the fronthaul network, i.e., multi-access edge computing (MEC), will allow to instantiate some virtual network functions (VNF) in those computing resources. The backhaul of 5G networks will be based on optical technology, in particular WDM, due to its high capacity and flexibility. In this paper, we analyse the problem of VNF-provisioning in a metro ring-topology network equipped with MEC resources and with a WDM network connecting the edge nodes. In contrast to previous proposals, the method decides where VNFs must be instantiated but also the design of the virtual topology for the WDM metro network in order to reduce the service blocking ratio and the number of resources in operation.

Open Source Implementation of OpenConfig Telemetry-Enabled NETCONF Agent

Abstract: Next generation networks are evolving towards disaggregated schemes, where the structure of the optical nodes presents multiple components to be combined and built into a complete solution (i.e., white-box concept). In such a scenario, operators and service providers are supporting vendor neutrality to enhance devices interoperability, simplify the control-plane operation and reduce network costs. OpenConfig is a working group of network operators focused on the definition of a set of vendor-neutral data models allowing dynamicity and programmability of the infrastructure by means of software-defined networking paradigm. Moreover, the telemetry functionality is a novel solution for network monitoring in which real time data and statistics are efficiently streamed from devices.In this paper, we propose an open-source implementation of an OpenConfig NETCONF agent enhanced with telemetry. The adoption of the gRPC-based telemetry allows the streaming of monitoring parameters from the transponders. In fact, the controller is able to request the streaming of one or more selected parameter(s), on demand and with proper granularity, in order to detect and localize the presence of a fault or identify hardware degradation. The implemented telemetry-enabled NETCONF agent for transponders has been experimentally validated over an Elastic Optical Networks (EON) scenario, highlighting the main functionalities and the effectiveness of the proposed solution.

SDN/NFV-Based Network Resource Management for Converged Optical-Wireless Network Architectures

Abstract: This paper proposes a methodology for the efficient allocation of both optical and wireless resources in an SDN/NFV-based converged optical-wireless network architecture. Our approach considers a network slicing architecture where different network slices form end-to-end logically isolated networks, each one dedicated to a different type of service with diverse requirements. The target of the proposed approach is to optimally determine the network slices so that the specific delay and bandwidth requirements of the multiple services are met, by considering both the optical and wireless network resources.

Challenges Due to Rayleigh Backscattering in Radio over Fibre Links for the Square Kilometre Array Radio-Telescope

Abstract: In the realization of the Low Frequency Aperture Array (LFAA) within the Square Kilometre Array (SKA) project, the radiofrequency (RF) signals coming from sky and celestial sources, and received by each of the 130k+ antennas, are transmitted to the signal processing unit through analogue Radio over Fibre links. Within this low frequency band, the relatively low levels of the power of such RF signals may give rise to unexpected distortion effects. The present works highlights the physical origin of such undesired spurious frequencies generation, which can be also found in other applicative telecommunications scenarios. The details of a possible solution able to keep the above mentioned distortion terms at acceptably low levels are finally illustrated.

A Broadband Polarization-Insensitive Diffractive Lens Design for Subwavelength Focusing of Light

Abstract: In this study, we propose the metaheuristic design of a polarization-insensitive diffractive lens. The designed lens structure consists of concentric dielectric rings with optimally modulated widths and heights. Here, the evolutionary optimization approach is conducted to find the optimum values of concentric rings’ widths and heights to obtain polarization-insensitive subwavelength focusing effect of the incident light. Three-dimensional finite-difference time-domain (3D FDTD) method is incorporated with the optimization algorithm to evaluate the focusing ability of instantly designed lens structures throughout the optimization process. The presented lens structure is designed at operating frequency of 10 GHz, and has a diameter of 18.45 cm with thickness of 2.4 cm. The detailed analysis of the polarization-insensitive focusing effect of designed diffractive flat lens is numerically investigated at microwave frequency regime considering the scenario of experimental verification to be conducted at the same spectral region. Possible experimental verifications are discussed along with the 3D-printing of the designed lens structure. As a further step, the presented design concept may be applied to design metasurfaces operating at visible wavelengths.

Impact of Distributed Processing on Power Consumption for IoT Based Surveillance Applications

Abstract: With the rapid proliferation of connected devices in the Internet of Things (IoT), the centralized cloud solution faces several challenges, out of which, power consumption is one of the top priorities among the research community. In this paper, we evaluate the impact of demand splitting over heterogeneous processing resources in an IoT platform, supported by Fog and Cloud infrastructure. We develop a Mixed Integer Linear Programming (MILP) model to study the gains of splitting resource intensive demands among IoT nodes, Fog devices and Cloud servers. A surveillance application is considered, which consists of multiple smart cameras capable of capturing and analyzing real-time video streams. The PON access network aggregates IoT layer demands for processing in the Fog or the Cloud, which is accessed through the IP/WDM network. For typical video analysis workloads, the results show that, splitting medium demand sizes among IoT and Fog resources yields a total power consumption saving of up to 32%, even if these layers can host only 10% of the total workload and this can reach up to 93% for lower number of demands, compared to the centralized cloud solution. However, the gains in power savings from splitting decreases as the number of splits increases.

Energy Efficient Virtual Machine Services Placement in Cloud-Fog Architecture

Abstract: The proliferation in data volume and processing requests calls for a new breed of on-demand computing. Fog computing is proposed to address the limitations of cloud computing by extending processing and storage resources to the edge of the network. Cloud and fog computing employ virtual machines (VMs) for efficient resource utilization. In order to optimize the virtual environment, VMs can be migrated or replicated over geo-distributed physical machines for load balancing and energy efficiency. In this work, we investigate the offloading of VM services from the cloud to the fog considering the British Telecom (BT) network topology. The analysis addresses the impact of different factors including the VM workload and the proximity of fog nodes to users considering the data rate of state-of-the-art applications. The result show that the optimum placement of VMs significantly decreases the total power consumption by up to 75% compared to a single cloud placement.

Assessing the Impact of Design Options for an Optical Switch in Network Routing Impairments

Abstract: In order to enable the maximum capacity in state-of-the art optical networks, a full orchestration with the physical layer is mandatory. Such an objective is obtained by abstracting network elements starting from the component design up to the networking management. To this purpose, a software (SW) environment which is vertically integrated across the networking layers is a mandatory support for engineering network infrastructure, or to virtually test the impact of a component design option on higher layer performance. Synopsys proposes an integrated SW environment for photonic integrated circuit (PIC) and system design that aims at satisfying this requirement: it is the integration of OptSim© -optical communication system, OptSim Circuit -schematic-driven photonic circuit, OptoDesigner© -mask layout, and RSoft component design tools. These tools have proven to be reliable aids to virtually designing and estimating the performance of optical transmission systems and photonic chips. In this work, we rely on such an integrated SW environment to assess the impact on networking operations of design options for an optical switch in Silicon Photonics using Analog Photonics (AP) Process Design Kit (PDK) component library elements [1]. Specifically, we address the transmission impairments and consequent reduction in Quality- of-Transmission (QoT) implied by multi-hop routing in meshed optical networks. Using the vertical integration of the Synopsys SW environment, we analyze the considered optical switch and by simulation, we obtain a layer-0 abstraction. So, we simulate its propagation impact, assessing a QoT-degradation depending on the design option and also depending of the choice for the transmission technique. Finally, we derive the impact of network routing addressing the QoT degradation vs. number of traversed switches.

Coexistence of Discrete-Variable QKD with WDM Classical Signals in the C-Band for Fiber Access Environments

Abstract: In this paper, a coexistence scheme between a Discrete-Variable Quantum Key Distribution (DV-QKD) and four bidirectional classical channels in a Passive Optical Network (PON) topology is theoretically investigated. The study aims to explore the imposed limitations considering the coexistence of weak quantum channels with realistic traffic flows of classical streams through shared fiber infrastructures. Based on a ‘plug and play’ phase coding DV-QKD implementation, we conducted numerical simulations of the QBER and the secure key rate for fiber distances up to 10 km. The reported results suggest that in a fixed C-band grid, the spectral isolation between classical and quantum channels is essential at dense grids. By removing the leakage noise through stronger spectral isolation, the photons linked with the Raman scattering become the dominant noise source, since this mechanism covers an ultra-broadband window and gets stronger as the propagation distance increases.

New Generation of Materials for the Near-Mid IR Sensors Based on Lead Chalcogenides

Abstract: For the first time the lead chalcogenide thin films of different chemical compositions – PbS, PbSe, PbTe and PbSeTe were synthesized via Chemical Vapor Deposition (CVD). High-pure elemental lead, sulphur, selenium and tellurium were utilized as the starting materials. The in-situ Optical Emission Spectroscopy (OES) was employed to pinpoint the mechanism of plasma-chemical interactions between precursors. The AFM study confirms the best quality of the surface morphology of the films. The IR study proves the wide working rage of the prepared materials.

Optimized Beam Size of Optical Ground-to-Satellite Link over Turbulence and Beam-Wandering

Abstract: The performance of a laser beam traveling in uplink from a ground-to-satellite is subjected to turbulence, and beam wandering. This paper evaluates the performance of the optical uplink with the pulse position modulation (PPM) scheme in order to determine the optimum beam size that minimizes the symbol error rate (SER) and outage probability. Close-form expressions for SER and outage probability are derived by considering the combined effect of turbulence, and beam wandering. Appropriate simulation scenarios are applied, and numerical results are verified the accuracy of the derived close-form expressions. The results show that the optimum beam size is 2.5 with zenith angle changes from 0 to 30°. Furthermore, this paper studies the system performance on optimized beam size by considering the effect of changing the zenith angle, the transmitter power and the modulation orders.

Observing and Modeling Wideband Generation of Non-Linear Interference

Abstract: Optical line systems are going beyond the C-band by exploiting multi-band transmission to expand the fiber capacity without installing new fiber cables. Moreover, operators are progressively pushing towards the implementation of the open optical network paradigm. This requires the capability to quickly estimate the lightpath Quality-of-Transmission (QoT) given by the generalized signal-to-noise ratio (GSNR), including both the effects of ASE noise and non-linear interference (NLI) accumulation. In order to predict the effect of NLI on GSNR degradation of multi-band OLS, we first observe that the NLI generation can be spectrally disaggregated, by separating the single-channel – self-phase modulation (SPM) – from the multi-channel effects – cross-phase modulation (XPM). Then, relying on the Gaussian-Noise model hypotheses, we derive a mathematical model to assess the multichannel impairments, validated by accurate split-step simulations. We show that the model conservatively predicts the disaggregated multi-channel NLI intensity with excellent accuracy.

Optical Power Budget Enhancement in 50 Gb/s IM-DD PONs with NOMA-CAP Modulation and SOA-Based Amplification

Abstract: Experimental results of a semiconductor optical amplifier (SOA) for optical amplification in an IM-DD NOMA-CAP optical access system with a data rate of 50 Gb/s are reported. Specifically, the SOA has been investigated as both booster and pre-amplifier for PON applications. The measured optical power budgets are 28.2 dB and 23.4 dB for the strong and weak NOMA levels, respectively, compared to the budgets for the strong and weak NOMA levels of 12.4 dB and 9.4 dB when no optical amplification is used.

TDM/WDM over AWGR Based Passive Optical Network Data Centre Architecture

Abstract: Passive Optical Data Centre Networks have been developed due to the performance limitations in current data centres to provide high performance within data centre networks. An AWGR based passive optical network data centre architecture is evaluated using a TDM/WDM multiple access technique to provision the flow of traffic among the network efficiently. A Mixed Integer Linear Programming model is developed to optimise resource allocation in the architecture. Using WDM-TDM as a multiple access technique helps in solving issues such as oversubscription and congestion by allowing servers to make simultaneous transmissions of packets in different time slots. The results show that the provisioning / allocation of resource within the architecture is improved with improvements of up to 75% in resource utilisation.

Analog Radio over Fiber Links for Future 5G Radio Access Networks

Abstract: Bandwidth constraint in the radio access networks is, nowadays, a mayor problem in the implementation of next generation 5G mobile communications. In order to cope with increasing bandwidth demands, the use of the millimeter-wave (mmWave) spectrum, together with Radio over Fiber (RoF) technology has been proposed. In this work, we will present our recent advances in the generation of mmWave signals for 5G using Microwave Photonics.