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In the paper we present a branch and price approach to routing and spectrum allocation - a basic optimization problem in elastic optical networks. We formulate the problem as a mixed-integer program for which we develop a branch and price algorithm enhanced with such techniques as cutting planes for improving lower bounds for the optimal objective value, and a greedy and a simulated annealing heuristics...
This paper analyses the performances of major conventional spectrum allocation policies in elastic optical networks, in terms of time complexity, blocking probability and contiguous aligned available slot ratio. Simulation results show that the first-last fit allocation policy outperforms in terms of blocking probability and contiguous aligned available slot ratio compared to other spectrum allocation...
This paper focuses on the problem of regenerator placement in cloud-ready Elastic Optical Networks (EONs). We assume that the EON supports different modulation formats (MFs) under impairment constraints that are represented as the maximum transmission reach of the MFs. High spectrum effective MFs provide shorter transmission range what in the case of larger distances triggers the need to use regenerators...
We focus on the design of the logical layer on an optical infrastructure for three different architectures: fixed grid WDM with fixed-rate multilevel modulation, fixed-grid WDM with time-domain hybrid modulation formats and flexible grid. A fairly detailed physical layer modelling is considered in the network design algorithms. We perform a sensitivity analysis of network and physical layer parameters,...
A new algorithm for dynamic network virtualization over flexible-grid networks is proposed. The algorithm, called Hamming-Fit, aims to map each request in a zone of the physical network resembling as much as possible the topology of the virtual network (sub-graph mapping). To do so, every possible node set (with as many nodes as the virtual network) of the physical topology is analyzed and its suitability...
The NFV is focused at virtualizing network functions such as gateways, path computing devices, resource allocation mechanisms, proxies, firewalls and transcoders, traditionally carried out by specialized hardware devices, and migrating these functions to software-based appliances. In this paper, an analytic model for the NFV forwarding graph is proposed with the aim to optimize the execution time...
In this paper, we explore the performance criteria for the rejection probability reduction in WDM LANs of passive star topology. We propose a synchronous transmission WDMA protocol according which each station is capable of receiving more than one data packets during a time cycle, using more than one tunable receivers. Thus, the packet rejections at destination due to the receiver collisions are essentially...
The FABULOUS EU project proposes a solution for NG-PON2 based on a WDM FDM/FDMA approach, and aims at realizing a fully integrated silicon-photonics ONU. The effectiveness of the architecture is being proven with discrete components, and in this paper we report about the preliminary results achieved with real-time traffic transmission.
We present the final results of the EU FP7 ERMES project, which focused on the development of a WDM-PON colourless self-tuning transmitter based on RSOA self-seeding. Measurements obtained with a packaged O-band RSOA in a SFP+ compatible transmitter are reported at 1.25, 2.5 and 10 Gb/s for various drop fibre lengths, up to 6.3 km and 1 km respectively. We successfully demonstrated transmission over...
The main goal of the Cognitive Radio (CR) systems is the intelligent and efficient utilization of the radio spectrum. In this paper we introduce our survey in wideband spectrum measurement for studying the Terrestrial Digital Video Broadcasting (DVB-T) frequency bands that are one of the future candidates for cognitive radio applications. The actuality of this subject is that during 2013 Hungary changed...
In the last years, two main ICT enablers have been massively explored to enforce vehicular safety: GNSS-based positioning and wireless communications. In fact, by exchanging information on their respective positions, vehicles are expected to be timely aware of the hazards around them and, consequently, to be able to promptly react, hopefully decreasing the rate of accidents. Both wireless communications...
This paper shows the design and implementation of an UWB transmitter and a receiver built with discrete parts. The transmitter is based on a step recovery diode and the receiver is built around an ultra-high speed comparator. The circuits are designed in a manner, that all components are low cost discrete elements and both the transmitter and the receiver can be easily interfaced to low speed and...
In Intelligent Transport Systems, Cooperative Collision Avoidance (CCA) by active communication systems is increasingly drawing more attention in the research community. Particularly, in order to minimize the number of situations where high speeds can lead to severe consequences in case of accident. When two or more vehicles are involved in such events, it is necessary to reach a common agreement...
In this paper, we propose two heuristics to perform regenerator assignment in translucent elastic optical networks. The first one tries to use the modulation format with the highest spectral efficiency, whereas the other one aims to transmit the optical signal as far as possible before it undergoes into a regeneration process. The former deploys several regenerators but saves bandwidth. On the other...
We report on recent status of vertical cavity lasers emitting in the 1.3 µm waveband comprising AlInGaAs/InP active regions wafer fused to Al(Ga)As/GaAs distributed Bragg reflectors. This technique produces vertical cavity surface emitting lasers (VCSELs) emitting in 4 channels of the 1310 nm coarse wavelength division multiplexing band that enabled a new generation of transceivers operating at 40...
Here we present our recent results on nitride nanowire light emitting diodes. In particular, we discuss the single wire light emitting diode fabrication and coupling of single nanowire emitters with waveguides in order to form a functional photonic platform. We also discuss our recent advances towards flexible nitride nanowire devices. We propose a method to combine high flexibility of polymer films...
We numerically investigate the design of a wavelength de-multiplexer based on a tapered photonic crystal waveguide. The tapered waveguide is generated by reducing the width of the channel which, in turn, provides a gradual change in the effective index for the guided modes. Depending on the wavelength, the grading effect enables the propagating beam to be trapped at different spatial positions along...
Optical Tamm plasmon states are electromagnetic modes confined at the interface between a Bragg mirror and a metallic film. These states offer coupling to photonic states in a relatively narrow solid angle in both TM and TE polarizations, and quality factors of a few hundreds to thousands in the visible and near infrared domain with limited fabrication difficulties. When a metallic disk of a few microns...
Several research institutes and commercial foundries presently offer shared wafer processing services based on generic integration technology. We have characterized SOAs fabricated in such a platform and compare their performance to discrete devices fabricated in a dedicated commercial process. Despite some limitations (presently single polarization and only C-band available), the characteristics...
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