Dimitra Simeonidou's research while affiliated with University of Bristol and other places

Publications (100)

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Advanced interconnect technologies play a prominent role in scaling up the performance of data center networks. Spatial Division Multiplexing (SDM) photonic interconnects have been suggested as means to overcome capacity upgrade requirements and enable disaggregation in future data centers. Here, Holographic Optical Elements (HOE) are proposed for...
Conference Paper
We demonstrate an intelligent monitoring on-demand switching strategy at network nodes based on Bayesian optimization. It is shown that our proposed method achieves identical monitoring capability as complete system exploration while saving a lot of data.
Conference Paper
This paper focuses on Converged Access/Metro Infrastructures for 5G services proposing the novel “Dis-Aggregated RAN” architecture adopting “disaggregation” of hardware and software components across wireless, optical and compute/storage domains. The proposed approach is theoretically evaluated.
Conference Paper
this work presents a comparison between C-RAN and emerging DA-RAN approaches for 5G networks. Main results show that DA-RAN and splitting alternative to CPRI bring economical and architectural advantages.
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Holographic Optical Elements couplers for photonic interconnects based on Spatial Division Multiplexing in multi core fibres are designed and studied with respect to their flexibility and tolerance to fabrication and integration errors.
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An open platform over OpenStack for control and management of experiments (O2CMF) for merging and adapting wireless and optical federated testbeds with proper cloud infrastructure is presented. TOSCA-enabled orchestration provides programmability for NFV experiments.
Conference Paper
This paper describes a demonstration of an end-to-end, SDN-controlled Video Contribution Network providing dynamic service set-up, using optical switching to enable flexible provisioning of resources. We show seamless operation of legacy and future technologies.
Conference Paper
We experimentally demonstrate, for the first time, DDoS mitigation of QKD-based networks utilizing a software defined network application. Successful quantum-secured link allocation is achieved after a DDoS attack based on real-time monitoring of quantum parameters.
Conference Paper
We successfully demonstrated a novel performance learning method using monitoring and Gaussian process. After 436km dark fiber transmission the model captures most of the test data with 0.7dB mean error and enables robust QoT predictor.
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Scientific applications demand huge computational power connected through fast networks. They are developed using parallel kernel methods, usually implemented with the Message Passing Interface (MPI), presenting well-behaved communication patterns across computing nodes. The current network technologies do not allow defining traffic forwarding poli...
Conference Paper
We will demonstrate the composition and operation of a virtual infrastructure (VI) for NFV content delivery. The demonstrated VI will be controlled through SDN controller. Furthermore, an infrastructure replanning mechanism will be also demonstrated
Conference Paper
Drawing from experience gained through the Bristol-Is-Open project, we will discuss the opportunity of utilising flexible optical and 5G wireless connectivity for supporting emerging smart-city services including autonomous transport, connected homes and critical event prevention/management.
Conference Paper
We propose a novel routing and spectrum allocation solution for elastic all-optical networks based on load-aware nonlinear impairment estimation that significantly improves service acceptance ratio and spectrum utilization compared to nonlinearity assignment based on fixed-margins.
Conference Paper
We propose a scheme to introduce real-time optical layer monitoring into optical network virtualization enabled by software defined networking. The optical layer factors that impact the virtualization are characterised and investigated using this scheme experimentally.
Conference Paper
We experimentally demonstrate a monitoring scheme utilizing both intermediate node and receiver monitoring for network re-planning. Either modulation format switching or light-path re-routing is adopted for restoration. The recovered signal performs better compared with static planning.
Conference Paper
An integrated software stack made up of extended OpenStack, OpenDaylight and custom OpenFlow agents enabling Virtual Data Centre deployment on an all-optical architecture employing hollow-core fibre, TDM fast switches and a circuit switched backplane.
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This paper focuses on the design of service provision-ing schemes suitable for mega data center (DC) infrastructures. A major issue linked with the operation of these infrastructures is scalability caused by the increased number of resources available in megasize highly dense DCs and the associated requirements for control and management informatio...
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Network virtualization is an emerging technique that enables multiple tenants to share an underlying physical infrastructure, isolating the traffic running over different virtual infrastructures/tenants. This technique aims to improve network utilization, while reducing the complexities in terms of network management for operators. Applied to this...
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This paper reports an FPGA-based switch and interface card (SIC) and its application scenario in an all-optical, programmable disaggregated data center network (DCN). Our novel SIC is designed and implemented to replace traditional optical network interface cards, plugged into the server directly, supporting optical packet switching (OPS)/optical c...
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The current Internet infrastructure is not able to support independent evolution and innovation at physical and network layer functionalities, protocols and services, while at same time supporting the increasing bandwidth demands of evolving and heterogeneous applications. This paper addresses this problem by proposing a completely democratized opt...
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This paper analyzes methodologies that allow scaling properly Architecture-On-Demand (AoD) based optical networks. As Data Centers and HPC systems are growing in size and complexity, optical networks seem to be the way to scale the bandwidth of current network infrastructures. To scale the number of servers that are connected to optical switches no...
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Modern high-performance data centers are responsible for delivering a huge variety of cloud applications to the end-users, which are increasingly pushing the limits of the currently deployed computing and network infrastructure. All-optical dynamic data center network (DCN) architectures are strong candidates to overcome those adversities, especial...
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There is no denying the tremendous success of current optical network technologies. However, the existing optical network infrastructures are unable to support independent evolution and innovation of physical, transport, and network layer functionalities, protocols, and services. Nor can they support the increasing bandwidth demands of evolving app...
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A virtualization architecture is presented for deploying multitenant virtual networks on top of multi-technology optical networks. A multidomain network hypervisor (MNH) and a multidomain SDN orchestrator (MSO) are introduced with this purpose. The MNH provides an abstract view of each virtual network and gives control of it to each independent cus...
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Multi-tenancy is a key feature of modern data centers. It allows for the existence of multiple independent virtual infrastructures, called virtual slices, on top of the same physical infrastructure, each of them specially tailored to the tenants' needs. In such a scenario, an optimal mapping of the virtual slices plays a capital role toward an effi...
Conference Paper
We summarized the development of Venture Photonics’ sub-10 ns fast optical switch which demonstrates low insertion loss, excellent crosstalk level and polarization independent switching performance.
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Single Mode Fiber's physical capacity boundaries will soon be reached, so alternative solutions are much needed to overcome the multiplying and remarkably large bandwidth requests. Space division multiplexing (SDM) using multicore fibers (MCF), multi-element fibers (MEF), multimode fibers (MMF) and their combination; few-mode multicore fibers (FM-M...
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Future high-performance network-based applications are delivered over the high-capacity dynamic optical network. Each of these applications requires dedicated network service, which can be provided by the virtual optical network (VON) created by optical network virtualization. The virtualizable bandwidth variable transceiver (V-BVT) is a key enabli...
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Based on the analysis of data centre (DC) traffic pattern, we introduced a holistic software-defined optical DC solution. Architecture-on-Demand based hybrid optical switched (OPS/OCS) data centre network (DCN) fabric is introduced, which is able to realise different inter-and intra-cluster configurations and dynamically support diverse traffic in...
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We introduce a holistic solution for softwaredefined optical data centres (DC). Hybrid optical circuit/packet switching technologies are employed in the data plane, while a software-defined networking (SDN) controller based on OpenDaylight with significant extensions is adopted for the data centre network (DCN) control and management. Novel functio...
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Optical packet switching (OPS) can enhance the performance of data center networks (DCNs)by providing fast and large-capacity switching capability. Benefiting from the software-defined networking (SDN) control plane, which could update the look-up-table (LUT) of the OPS, virtual DCNs can be flexibly created and reconfigured. In this work, we have i...
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Optical networking technologies are very attractive for intra-DataCenter (DC) interconnectivity due to their intrinsic high-bandwidth and low-latency characteristics. As the bandwidth demand grows, quantity and size of IT and network infrastructure grows, which puts pressure on power, cost, and space consumption. Therefore, programmable optical net...
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Mobile computation offloading has been identified as a key-enabling technology to overcome the inherent processing power and storage constraints of mobile end devices. To satisfy the low-latency requirements of content-rich mobile applications, existing mobile cloud computing solutions allow mobile devices to access the required resources by access...
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Optical Ethernet gains great success in varied optical domains. Ethernet while providing the elastic allocation of bandwidth per flow is currently restricted to being transported over fixed-rate fixed-grid optical channels. However, as data transmission and switching in optical networks is becoming more flexible, the current Ethernet to optical int...
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A scheme for the conversion of spatially multiplexed channels to a wavelength superchannel is presented and characterized. The viability of deployment of this scheme at network nodes located at the boundaries between spatial-division-multiplexed and standard single-mode fiber wavelength division multiplexed networks is demonstrated.
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A multidomain optical transport network composed of heterogeneous optical transport technologies (e.g., flexi/fixed-grid optical circuit switching and optical packet switching) and control plane technologies (e.g., centralized OpenFlow or distributed GMPLS) does not naturally interoperate, and a network orchestration mechanism is required. A networ...
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Future networks are set to provide a wide range of services over a multitude of technologies carrying a broad range of traffic profiles. The emerging mobile cloud computing applications are imposing numerous challenges on network operators to enable ubiquitous and on-demand service provisioning. To cope with the rising demands wired and wireless ne...
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The dramatic growth of Internet traffic is posing unprecedented challenges in all network segments. Moreover, its increasing heterogeneity is driving research trends in network functions virtualization and software-defined networking (SDN) to guarantee high levels of reconfigurability, adaptability, and flexibility. Therefore, hardware infrastructu...
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We propose a sliceable bandwidth variable transceiver (S-BVT) architecture suitable for metro/regional elastic networks and highly scalable data center applications. It adopts multicarrier modulation, either OFDM or DMT, and a cost-effective optoelectronic front-end. The high-capacity S-BVT is programmable, adaptive, and reconfigurable by an SDN co...
Conference Paper
A network hypervisor is introduced to dynamically deploy multi-tenant virtual networks on top of multi-technology optical networks. It provides an abstract view of each virtual network and enables its control through an independent SDN controller.
Conference Paper
A new architecture utilizing combination of SDN and NFV for deeply programmable optical Internet infrastructure is proposed where network devices can be sliced, interconnected and programmed on demand for specific transport and network computing tasks.
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Reconfigurable optical add/drop multiplexers (ROADMs) are key elements in operators’ backbone networks. The breakthrough node concept of architecture on demand (AoD) permits us to design optical nodes with higher flexibility with respect to ROADMs. In this work, we present a five-step algorithm for designing AoD instances according to some given tr...
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In order to serve the future high-performance network-based Internet applications, optical network virtualization is proposed to offer each application type a dedicated virtual optical network (VON). Virtualize-able bandwidth variable transceiver (V-BVT) is a key enabler in supporting the creation of multiple VONs. In this paper, we present a feasi...
Conference Paper
A real-time Ethernet to reconfigurable superchannel data converter is demonstrated in a flexigrid EON network. Ethernet packets are aggregated and groomed by an FPGA-based optoelectronics to a reconfigurable superchannel signal with variable capacity from 160Gbit/s to 2.56Tbit/s.
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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...
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Programmable optical nodes supporting heterogeneous traffic require optical backplanes with a high port count. We present two backplane architectures to enhance modularity, compare their scalability in terms of available cross-connections and we experimentally validate both proposals in a SDN scenario.
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This study looks into network planning issues for synthetic MCF-based SDM networks implemented through programmable ROADMs. The results show that significant savings in switching modules and energy can be attained by exploiting the flexibility inherent in programmable ROADM through a proper network design.
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Photonic and Electronic Network Function Programmability (NFP) is proposed to unlock infrastructure and architecture flexibility. A Software Defined Network Synthesis framework based on NFP hardware layers is introduced for both Data Centres and Future Internet.
Conference Paper
The paper demonstrates the concept of optical networks with nodes implemented by the architecture on demand (AoD) and proposes a procedure for finding out possible benefits of AoD application, related to node and network availability. AoD node structure enables efficient failure management by creating a set of redundant components, which can be use...
Conference Paper
Current over-provisioned and multi-tier data centre networks (DCN) deploy rigid control and management platforms, which are not able to accommodate the ever-growing workload driven by the increasing demand of high-performance data centre (DC) and cloud applications. In response to this, the EC FP7 project LIGHTNESS (Low Latency and High Throughput...
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The paper presents architecture, implementation and evaluation of optical network function programmable node with hitless inter-function and intra-function switch-over. It supports multiple network functions on opto-electronic programmable hardware providing function-based virtualization and high network performance.
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We report new research targeting optical layer programmability and virtualisation for advanced DC and Cloud infrastructures. We focus on novel coordinated software-hardware solutions to unlock flexibility, programmability and resource sharing in the optical layer. Article not available.
Conference Paper
Novel hard-wired and synthetic ROADM architectures with self-healing capabilities are experimentally demonstrated. Simulation results show significant improvements of availability and recovery time due to node-level restoration, with reduced mean down time and operator revenue losses.
Conference Paper
Architecture design extensions for Time Shared Optical Network (TSON) are proposed for mobile backhaul. It introduces higher rates, flexible sub-lambda or lambda modes of operation, and dynamic memory allocation facilitating infrastructure virtualization and reprogramming.
Conference Paper
We propose a resource broker to dynamically provision multi-domain VON across heterogeneous control (GMPLS, OpenFlow) domains and transport (OPS, EON) technologies. Experimental evaluation has been performed in an international testbed across Spain, UK and Japan.
Conference Paper
A cost-effective time-sliceable IM/DD OFDM transceiver using low-complex DSP is experimentally investigated. Slicing capabilities are tested for concurrently serving 12.5GHz channels running at up to 10Gb/s variable bandwidth optical routes covering up to 185km.
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Architecture on demand (AoD) node offers considerable flexibility against traditional ROADMs. The paper presents a cost-efficient network planning strategy that exploits the flexibility inherent in AoD. Results show that AoD can save significantly in node modules through a proper network design.
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We introduce add/drop on demand (ADoD) architecture for ROADMs to provide higher flexibility and lower loss than current proposals. We quantitatively measure flexibility considering system’s entropy and associate it with traffic uncertainty, upgradability, and resilience.
Conference Paper
The first experimental demonstrator of 46-108Gbps discrete-multi-tone (DMT) fixed-length variable capacity OPS over programmable, flexi-grid elastic optical path network (EON), orchestrated via multiple OpenFlow controllers in the framework of SDN is presented.
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Applications running inside data centers are enabled through the cooperation of thousands of servers arranged in racks and interconnected together through the data center network. Current DCN architectures based on electronic devices are neither scalable to face the massive growth of DCs, nor flexible enough to efficiently and cost-effectively supp...
Conference Paper
SDN/OpenFlow solutions have shown their strengths in datacenter, cloud and experimental environments. Currently there is a number of activities employing SDN concepts to other use cases. The ADDONAS project (Active Distributed & Dynamic Optical Network Access Systems) proposed to use SDN concept to support access to the services for the users and f...
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New and emerging Internet applications are increasingly becoming high-performance and network-based, relying on optical network and cloud computing services. Due to the accelerated evolution of these applications, the flexibility and efficiency of the underlying optical network infrastructure as well as the cloud computing infrastructure [i.e., dat...
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This paper focuses on the design of multiple dependable virtual infrastructures (VIs) over converged optical network and IT resources supporting uncertain elastic cloud services. VI dependability is defined as the VI ability to offer resilience in the case of IT resource failures and security guarantees in terms of isolation of VIs that share a com...
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This paper reports on the design, implementation, and evaluation of a multitechnology, multirate, and adaptable network architecture for metropolitan/edge areas. It is empowered by programmability in control and data planes, providing users with an open network platform to redefine and optimize its behavior and performance. It uses a hybrid data pl...