A Survey of Quality of Service Differentiation Mechanisms for Optical Burst Switching Networks

Cataloged from PDF version of article.This paper presents an overview of Quality of Service (QoS) differentiation mechanisms proposed for Optical Burst Switching (OBS) networks. OBS has been proposed to couple the benefits of both circuit and packet switching for the ‘‘on demand’’ use of capacity in the future optical Internet. In such a case, QoS support imposes some important challenges before this technology is deployed. This paper takes a broader view on QoS, including QoS differentiation not only at the burst but also at the transport levels for OBS networks. A classification of existing QoS differentiation mechanisms for OBS is given and their efficiency and complexity are comparatively discussed. We provide numerical examples on how QoS differentiation with respect to burst loss rate and transport layer throughput can be achieved in OBS networks. © 2009 Elsevier B.V. All rights reserved

Benchmarking and viability assessment of optical packet switching for metro networks

Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained

Performance of translucent optical networks under dynamic traffic and uncertain physical-layer information

This paper investigates the performance of translucent Optical Transport Networks (OTNs) under different traffic and knowledge conditions, varying from perfect knowledge to drifts and uncertainties in the physical-layer parameters. Our focus is on the regular operation of a translucent OTN, i.e., after the dimensioning and regenerator placement phase. Our contributions can be summarized as follows. Based on the computation of the Personick’s Q factor, we introduce a new methodology for the assessment of the optical signal quality along a path, and show its application on a realistic example. We analyze the performance of both deterministic and predictive RWA techniques integrating this signal quality factor Q in the lightpath computation process. Our results confirm the effectiveness of predictive techniques to deal with the typical drifts and uncertainties in the physical-layer parameters, in contrast to the superior efficacy of deterministic approaches in case of perfect knowledge. Conversely to most previous works, where all wavelengths are assumed to have the same characteristics, we examine the case when the network is not perfectly compensated, so the Maximum Transmission Distance (MTD) of the different wavelength channels may vary. We show that blocking might increase dramatically when the MTD of the different wavelength channels is overlooked.Postprint (published version

Benchmarking and viability assessment of optical packet switching for metro networks

Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained

A survey of quality of service differentiation mechanisms for optical burst switching networks

This paper presents an overview of Quality of Service (QoS) differentiation mechanisms proposed for Optical Burst Switching (OBS) networks. OBS has been proposed to couple the benefits of both circuit and packet switching for the "on demand" use of capacity in the future optical Internet. In such a case, QoS support imposes some important challenges before this technology is deployed. This paper takes a broader view on QoS, including QoS differentiation not only at the burst but also at the transport levels for OBS networks. A classification of existing QoS differentiation mechanisms for OBS is given and their efficiency and complexity are comparatively discussed. We provide numerical examples on how QoS differentiation with respect to burst loss rate and transport layer throughput can be achieved in OBS networks. © 2009 Elsevier B.V. All rights reserved

Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core–Shell Particle for Protein Adsorption and pH-Controlled Release

Magnetic nanoparticle composite with a cobalt ferrite (CoFe2O4, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH

Human Fibroblast Sheet Promotes Human Pancreatic Islet Survival and Function In Vitro

In previous work, we engineered functional cell sheets using bone marrow-derived mesenchymal stem cells (BM-MSCs) to promote islet graft survival. In the present study, we hypothesized that a cell sheet using dermal fibroblasts could be an alternative to MSCs, and then we aimed to evaluate the effects of this cell sheet on the functional viability of human islets. Fibroblast sheets were fabricated using temperature-responsive culture dishes. Human islets were seeded onto fibroblast sheets. The efficacy of the fibroblast sheets was evaluated by dividing islets into three groups: the islets-alone group, the coculture with fibroblasts group, and the islet culture on fibroblast sheet group. The ultrastructure of the islets cultured on each fibroblast sheet was examined by electron microscopy. The fibroblast sheet expression of fibronectin (as a component of the extracellular matrix) was quantified by Western blotting. After 3 days of culture, islet viabilities were 70.2 ± 9.8%, 87.4 ± 5.8%, and 88.6 ± 4.5%, and survival rates were 60.3 ± 6.8%, 65.3 ± 3.0%, and 75.8 ± 5.6%, respectively. Insulin secretions in response to high-glucose stimulation were 5.1 ± 1.6, 9.4 ± 3.8, and 23.5 ± 12.4 μIU/islet, and interleukin-6 (IL-6) secretions were 3.0 ± 0.7, 5.1 ± 1.2, and 7.3 ± 1.0 ng/day, respectively. Islets were found to incorporate into the fibroblast sheets while maintaining a three-dimensional structure and well-preserved extracellular matrix. The fibroblast sheets exhibited a higher expression of fibronectin compared to fibroblasts alone. In conclusion, human dermal fibroblast sheets fabricated by tissue-engineering techniques could provide an optimal substrate for human islets, as a source of cytokines and extracellular matrix