1,721,065 research outputs found
Tandem Architecture for Photonic Packet Switches
No full textA new switch architecture is presented to enhance outputqueuing in photonic packet switches. Its application is for apacket switching environment based on the optical transport offixed length packets. This architecture consists of a couple of cascadingswitching elements with output queuing, whose buffer capacityis limited by photonic technology. The introduction of asuitable buffer management allows a very good and balanced exploitationof the available optical memories, realized with fiber delaylines. In particular, packet loss performance is here evaluatedshowing the improvement with respect to the single switch anda way to design large optical switches is shown in order to meetbroadband network requirements
Differentiated protection in 5G vehicular networks
No full textAutomotive applications need high reliability and service continuity to support self-driving and safety in smart city environments. Suitable allocation of network functions is studied and optimal solutions based on Integer Linear Programming methodology are found. Differentiated reliability concept is applied in the presence of two different 5G classes of service, namely eMBB and URLLC. Saving of processing and bandwidth resources is numerically evaluated by combining service-based shared and dedicated protection in a reference scenario. Scalability aspects of the approach are also discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Optimization over time of reliable 5G-RAN with network function migrations
Full text linkResource optimization in 5G Radio Access Networks (5G-RAN) has to face the dynamics over time in networks with increasing numbers of nodes and virtual network functions. In this context, multiple objectives need to be jointly optimized, and key application requirements such as latency must be enforced. In addition, virtual network functions realizing baseband processing are subject to failures of the cloud infrastructure, requiring an additional level of reliability. Overall, this is a complex problem to solve, requiring fast algorithms to cope with dynamic networks while avoiding resource overprovisioning. This paper considers the problem of optimal virtual function placement in 5G-RAN with reliability against a single DU Hotel failure and proposes a solution that takes service dynamics into account. Firstly, the joint optimization of the total number of DU Hotels, of the RU-DU latency and of the backup DU sharing in a static traffic scenario is considered, and the DUOpt algorithm, based on Lexicographic Optimization, is proposed for solving efficiently this multiobjective problem. DUOpt splits the multi-objective problem into smaller Integer Linear Programming (ILP) subproblems that are sequentially solved, adopting for each one the most effective methodology to reduce the total execution time. The proposed DUOpt algorithm is extensively benchmarked to show its effectiveness in optimization of medium to large size networks: in particular, it is shown to greatly outperform an aggregate multi-objective approach, being able to compute optimal or close to optimal solutions for networks of several tens of nodes in computing times of a few seconds. Then, the problem is extended to a dynamic traffic scenario in which optimization is performed over time. In this context, in addition to the aforementioned objectives, the total number of network function migrations induced by multiple reoptimizations must be kept to the minimum. For solving efficiently this problem the DUMig algorithm is proposed, which extends and improves DUOpt. Reoptimization over a time horizon of one day in an illustrative dynamic traffic scenario is performed to evaluate the proposed DUMig algorithm against DUOpt, the latter being oblivious of the traffic dynamics. DUMig shows remarkable savings in the total number of migrations (above 86.1% for primary virtual functions and 83% for backup virtual functions) compared to DUOpt, while preserving near-optimal resource assignment
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Network Slicing Automation: Challenges and Benefits
No full textNetwork slicing is a technique widely used in 5G networks where multiple logical networks (i.e., slices) run over a single shared physical infrastructure. Each slice may realize one or multiple services, whose specific requirements are negotiated beforehand and regulated through Service Level Agreements (SLAs). In Beyond 5G (B5G) networks it is envisioned that slices should be created, deployed, and managed in an automated fashion (i.e., without human intervention) irrespective of the technological and administrative domains over which a slice may span. Achieving this vision requires a combination of novel physical layer technologies, artificial intelligence tools, standard interfaces, network function virtualization, and software-defined networking principles. This paper provides an overview of the challenges facing network slicing automation with a focus on transport networks. Results from a selected group of use cases show the benefits of applying conventional optimization tools and machine-learning-based techniques while addressing some slicing design and provisioning problems
Packet Optical Networks for High Speed TCP-IP Backbones
No full textThis article presents a new proposal for TCP-IP backbone.The proposed architecture merges the flexibility in resource management of packet switching with the high capacity offered by full optical technology
From IoT to cloud: Applications and performance of the MQTT protocol
No full textA study of the MQTT publish/subscribe protocol with different QoS levels is presented with the aim to extend the Internet of Things (IoT) concept across access, edge and transport networks and reach cloud computing facilities. A simple testbed is set up with related software components to measure the end-to-end delivery latency between the publisher and the subscribers and the impact of the network delay caused by network configurations with different service deployments. In particular, the latency is shown to rise up to more than 7 times the average network delay when the QoS 2 level is applied, thus indicating that its adoption must be carefully considered
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