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Reliability and security of vector routing protocolsLi, Yan, doctor of computer science 01 June 2011 (has links)
As the Internet becomes the ubiquitous infrastructure for various applications, demands on the reliability, availability and security of routing protocols in the Internet are becoming more stringent. Unfortunately, failures are still common in the daily operation of a network. Service disruption for even a short time can seriously affect the quality of real-time applications, such as VoIP and video on demand applications. Moreover, critical business and government
applications require routing protocols to be robust against malicious attacks, such as denial of Service attacks. This dissertation proposes three techniques to address some reliability and security
concerns in intra-domain (distance vector) routing protocols and
inter-domain (path vector) routing protocols.
The first technique addresses the problem of service disruption that
arises from sudden link failures in distance vector routing protocols. We consider two types of link failures: single link failures and shared risk link group failures. For single link failures, we propose an IP fast reroute mechanism to reroute packets around the failed
links. This fast reroute mechanism is the first that does not require
complete knowledge of the network topology and does not require
changing of the original routing protocol. This mechanism proactively computes a set of relay nodes that can be used to tunnel the rerouted
packets immediately after the detection of a link or node failure. The mechanism includes an algorithm for a node to automatically identify
itself as a candidate relay node for a reroute link and notify the
source node of the reroute link of its candidacy. The source node can
then decide the validity of a candidate relay node. The mechanism also includes an algorithm to suppress redundant notification messages. We then extend our IP fast reroute mechanism for single link
failures to accommodate shared risk link group failures. We achieve this goal by introducing one more bit information. Through
simulations, I show that the proposed mechanisms succeed in rerouting around failed links about 100% of the time, with the length of the reroute path being comparable to the length of the re-converged shortest path.
The second technique addresses the problem that arises from allowing
any node to route data packets to any other node in the network (and
consequently allow any adversary node to launch DoS attacks against
other nodes in the network). To solve this problem, we propose a
blocking option to allow a node u to block a specified set of
nodes and prevent each of them from sending or forwarding packets to node u. The blocking option intends to discard violating
packets near the adversary nodes that generated them rather than near their ultimate destinations. We then discuss unintentionally blocked nodes, called blind nodes and extend the routing protocols to allow each node to communicate with its blind nodes via some special nodes called joint nodes. Finally, I show, through extensive simulation, that the average number of blind nodes is close to zero when the average number of blocked nodes is small.
The third technique addresses the problem that arises when a set of
malicious ASes in the Internet collude to hijack an IP prefix from its legitimate owner in BGP. (Note that none of previous proposals for protecting BGP against IP prefix hijacking is effective when malicious
ASes can collude.) To solve this problem, we propose an extension of
BGP in which each listed AS in an advertised route supplies a
certified full list of all its peers. Then I present an optimization where each AS in an advertised route supplies only a balanced peer list, that is much smaller than its full peer list. Using real Internet topology data, I demonstrate that the average, and largest, balanced peer list is 92% smaller than the corresponding full peer list. Furthermore, in order to handle the dynamics of the Internet topology, we propose algorithms on how to issue certificates to reflect the latest changes of the Internet topology graph.
Although the results in this dissertation are presented in the context of distance vector and path vector routing protocols, many of these results can be extended to link state routing protocols as well. / text
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Μοντέλα ασυνήθους δικτυακής κυκλοφορίας σε TCP/IP δικτυακά υπολογιστικά περιβάλλοντα / Models of abnormal network traffic in TCP/IP networking computer environmentsΚομνηνός, Θεόδωρος 16 March 2009 (has links)
Στην διδακτορική διατριβή αναπτύξαμε μοντέλα για την ασυνήθη δικτυακή κυκλοφορία βασισμένη σε χαρακτηριστικά της TCP/IP επικοινωνίας ανάμεσα σε υπολογιστικά συστήματα, αλλά και στην συμπεριφορά συστημάτων και χρηστών κάτω από επιθέσεις ιών και δικτυακών σκουληκιών.
Για την ανάπτυξη συνδυάσαμε το μαθηματικό φορμαλισμό πάνω σε πραγματικά χαρακτηριστικά που εντοπίσαμε πως υπάρχουν σχεδόν σε όλες τις προσπάθειες επίθεσης προς υπολογιστικά και δικτυακά συστήματα από προσπάθειες επιτιθέμενων, αλλά και με αυτοματοποιημένα συστήματα μετάδοσης ιών.
Υλοποιήσαμε ένα πραγματικό κατανεμημένο σύστημα έγκαιρης και έγκυρης προειδοποίησης και λήψης άμεσων μέτρων για την προστασία δικτύων υπολογιστών από τη διάδοση των ιών και από τις διαρκώς εξελισσόμενες επιθέσεις των hackers. Τέλος η αυξανόμενη παρουσία δυνατοτήτων για fast worms μας παρακίνησε να μοντελοποιήσουμε την συμπεριφορά ιών που μεταδίδονται μέσα από τα κοινωνικά δίκτυα που σχηματίζονται από τον κατάλογο που έχουν οι χρήστες για γνωστούς και φίλους σε e-mail και Instant Messaging. Προτείνουμε λοιπόν δύο μοντέλα: ένα μοντέλο που περιγράφει την συμπεριφορά fast worms βασισμένα σε κοινωνικά δίκτυα στηριζόμενοι στο μαθηματικό μοντέλο σε Constraint Satisfaction Problems (CSP), αλλά και ένα μοντέλο για τη μετάδοση ιών και την εξουδετέρωσή τους, που λαμβάνει υπόψη την δικτυακή κίνηση και την λειτουργία των εξυπηρετητών βασισμένοι στο M/M/1 μοντέλο ουρών.
Στην διατριβή προτείνουμε ένα είδος διαδραστικότητας ανάμεσα στους antivirus Agents και τους ιούς και αναλύουμε ένα μαθηματικό μοντέλο για την διάδοση πληθυσμού ιών και antivirus βασισμένα σε θεωρίες ουρών. / In this PhD Thesis we developed models for the abnormal network traffic based on TCP/IP communication protocol of computer systems, and the behavior of systems and users under viruses and worms attacks.
For the development we combined mathematical formalism on real attributes that characterize almost all attacking efforts of hackers, virus and worms against computers and networking systems.
Our main goal was based upon the theoretic models we proposed, to provide a useful tool to deal with intrusions. Thus we developed a Software Tool for Distributed Intrusion Detection in Computer Networks. Based on an improved model we produced a real time distributed detection system for early warning administrators of worm and virus propagation and hackers’ attacks.
Also in this work we propose a discrete worm rapid propagation model based on social networks that are built using the address book of e-mail and instant messaging clients using the mathematic formalism of Constraint Satisfaction Problems (CSP). The address book, which reflects the acquaintance profiles of people, is used as a “hit-list”, to which the worm can send itself in order to spread fast. We also model user reaction against infected email as well as the rate at which antivirus software is installed. We then propose a worm propagation formulation based on a token propagation algorithm, further analyzed with a use of a system of continuous differential equations, as dictated by Wormald’s theorem on approximating “well-behaving” random processes with deterministic functions.
Finally in this work we present a virus propagation and elimination model that takes into account the traffic and server characteristics of the network computers. This model partitions the network nodes into perimeter and non-perimeter nodes. Incoming/outgoing traffic of the network passes through the perimeter of the network, where the perimeter is defined as the set of the servers which are connected directly to the internet. All network nodes are assumed to process tasks based on the M/M/1 queuing model. We study burst intrusions (e.g. Denial of Service Attacks) at the network perimeter and we propose a kind of interaction between these agents that results using the formalism of distribution of network tasks for Jackson open networks of queues.
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Υλοποίηση ενός SIP user agent στον δικτυακό επεξεργαστή Intel IXP 425Καρποδίνης, Πολυχρόνης 26 February 2009 (has links)
Θα περιγράψουμε τις βασικές λειτουργίες ενός VoIP δικτύου, τα συστατικά του μέρη, καθώς και τα πρωτόκολλα που είναι υπεύθυνα για την εγκατάσταση, τον έλεγχο και τον τερματισμό μιας VoIP υπηρεσίας-συνομιλίας. Τα πρωτόκολλα αυτά
ονομάζονται πρωτόκολλα σηματοδοσίας. Τα πρωτόκολλα σηματοδοσίας για VoIP εφαρμογές
και ιδιαίτερα το πρωτόκολλο SIP (Session Initiation Protocol) είναι το βασικό θέμα της
παρούσας εργασίας. Συγκεκριμένα, έγινε ανάπτυξη ενός SIP User Agent, το λογισμικό του
οποίου θα εκτελείται στο δικτυακό επεξεργαστή IXP425 της Intel, μαζί με τα απαραίτητα
πρωτόκολλα για την κωδικοποίηση-αποκωδικοποίηση και μετάδοση δειγμάτων φωνής σε μορφή πακέτων δεδομένων. Το αποτέλεσμα αναμένεται να είναι ένα ολοκληρωμένο προϊόν
(VoIP phone) για την πραγματοποίηση VoIP κλήσεων. / -
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Διερεύνηση παραμέτρων σύγκλισης μεταξύ δικτύων κινητής τηλεφωνίας και ασυρμάτων δικτύων δεδομένωνΖαφειρόπουλος, Διονύσης 27 August 2009 (has links)
Στην εν λόγω εργασία, έγινε μια προσπάθεια καταγραφής του τεχνολογικού τοπίου της τηλεπικοινωνιακής αγοράς, με έμφαση την διαλειτουργικότητα μεταξύ των Δικτύων Κινητής Τηλεφωνίας και των Ασύρματων Δικτύων Δεδομένων και των σχετικών αλλαγών που έχει επιφέρει αυτή η διαλειτουργικότητα, τόσο στις παρεχόμενες υπηρεσίες, όσο και στα εφαρμοζόμενα επιχειρηματικά μοντέλα από πλευράς εταιρειών της συγκεκριμένης αγοράς.
Στα πλαίσια αυτής της προσπάθειας, χρειάστηκε να πραγματοποιηθεί μια λεπτομερής καταγραφή των τεχνολογικών εξελίξεων, σε επίπεδο τεχνικών προδιαγραφών και προτύπων, στις παραπάνω δύο κατηγορίες δικτύων, ώστε να καταλήξουμε σε εκείνα τα πρότυπα που πλέον μπορούν να οδηγήσουν στην υλοποίηση δικτύων τα οποία θα χαρακτηρίζονται από τα παρακάτω:
• θα είναι ενοποιημένα ώστε οι διαφορετικές τεχνολογικές πλατφόρμες των εταιρειών να λειτουργούν απρόσκοπτα,
• θα χαρακτηρίζονται από χαμηλό κόστος,
• ο τελικός χρήστης θα μπορεί να είναι συνεχώς συνδεδεμένος με κάποιο δίκτυο ασύρματης πρόσβασης και να απολαμβάνει τις υπηρεσίες που επιθυμεί, οποτεδήποτε και οπουδήποτε.
Η δομή της διπλωματικής εργασίας ακολουθεί τον προαναφερθέντα τρόπο σκέψης. Στο 1ο Κεφάλαιο γίνεται μια σύντομη παρουσίαση του στόχου σε επίπεδο τεχνολογιών αλλά και υπηρεσιών, δηλαδή των αναμενόμενων αποτελεσμάτων αυτών των δικτύων νέας γενιάς, στα οποία έχουμε συνηθίσει να αναφερόμαστε ως δίκτυα 4G (4th Generation) ή δίκτυα B3G (Beyond 3G) ή τέλος ως All – IP ασύρματα δίκτυα.
Στο 2ο Κεφάλαιο, γίνεται μια λεπτομερής παρουσίαση των Δικτύων Κινητής Τηλεφωνίας από τις πρώτες τους εκδοχές (1G) έως τις πλέον σύγχρονες (3.5G) που έχουν εμφανιστεί μέχρι σήμερα. Αναλύονται τόσο οι γενιές των δικτύων όσο και τα χρησιμοποιούμενα πρότυπα, σε επίπεδο αρχιτεκτονικής όσο και σε επίπεδο πρωτοκόλλων. Στη συνέχεια του κεφαλαίου υπάρχει η τεχνική περιγραφή των επικρατέστερων δικτύων κινητής τηλεφωνίας, σήμερα, δηλαδή των GSM, GPRS και UMTS, ενώ στο τέλος του κεφαλαίου υπάρχει μια σύντομη περιγραφή της διαδικασίας intersystem handover μεταξύ των GSM και UMTS.
Στο 3ο Κεφάλαιο, περνάμε πλέον στα Ασύρματα Δίκτυα Δεδομένων. Γίνεται μια εκτενής περιγραφή των προτύπων που έχουν καθοριστεί και συγκεκριμένα στα πρότυπα IEEE 802.15 Wireless Personal Area Networks (WPANs) με κυριότερους εκφραστές τα δίκτυα βασιζόμενα σε Bluetooth και IrDA, το πρότυπο IEEE 802.11 Wireless Local Area Networks (WLANs) με σημαντικότερος εκπροσώπους τα WiFi και HyperLan/2, το πρότυπο IEEE 802.16 Wireless Metropolitan Area Networks (WMANs) ή αλλιώς γνωστότερο ως WiMAX και τέλος το πρότυπο IEEE 802.20 Wireless Wide Area Networks (WWANs) ή διαφορετικά Mobile Broadband Wireless Access (MWBA) το οποίο είναι υπό διερεύνηση ακόμα και φιλοδοξεί να αποτελέσει το ασύρματο ανάλογο της τεχνολογίας xDSL, καθώς θα προσφέρει ασύρματες ευρυζωνικές υπηρεσίες.
Στο 4ο Κεφάλαιο παρουσιάζονται μεθοδολογίες υλοποίησης του integration μεταξύ δικτύων των δύο κατηγοριών και συγκεκριμένα παραδείγματα διαλειτουργικότητας, όπως μεταξύ GPRS ή UMTS και WLANs ή μεταξύ UMTS και WiMAX. Γίνεται εκτενής συζήτηση γύρω από τα προβλήματα που θα πρέπει να αντιμετωπιστούν, όπως η εξασφάλιση ανεκτού επιπέδου QoS, οι μηχανισμοί για handover μεταξύ των δικτύων, η διαχείριση της κινητικότητας των χρηστών και των τερματικών και δίνονται παραδείγματα δημιουργίας ενοποιημένων δικτύων, τόσο με τη τεχνική της χαλαρής όσο και με την τεχνική της ισχυρής ζεύξης. Στο τελευταίο τμήμα του Κεφαλαίου, γίνεται μια εκτενής αναφορά στις αρχιτεκτονικές διασύνδεσης ετερογενών δικτύων με IP δίκτυα κορμού, τα γνωστά All – IP networks. Ιδιαίτερη έμφαση δίνεται στους μηχανισμούς πραγματοποίησης των handovers βάσει πολιτικών (policy based) και η χρήση τεχνικών για micromobility και macromobility σε σχέση με την κινητικότητα των τερματικών.
Το 5ο Κεφάλαιο αφορά τις εφαρμογές και υλοποιήσεις ασυρμάτων δικτύων δεδομένων στον Ελληνικό χώρο, στα πλαίσια του Επιχειρησιακού Προγράμματος «Κοινωνία της Πληροφορίας» και πιο συγκεκριμένα τα «Εξοπλισμός και δικτύωση σε όλες τις βαθμίδες της εκπαίδευσης», «Ασύρματα Ευρυζωνικά Δίκτυα ΟΤΑ»και «Μητροπολιτικά Ευρυζωνικά Δίκτυα Οπτικών Ινών ΟΤΑ» και ουσιαστικά αποτελούν παραδείγματα και υλοποιήσεις διασύνδεσης WiFi, WiMAX και IP backbone δικτύων όπως το ΣΥΖΕΥΞΙΣ με δυνατότητες για παροχή VoIP. / In this thesis, an effort of presenting the technological landscape of the telecommunication market takes place, with focus on the interoperability between the Mobile Telephony Networks and the Wireless Data Networks and the relative changes that have evolved through this interoperability, both regarding the provided services and the applied business models by the enterprises of the specific market.
Within the frames of this effort, a detailed recording of technological developments is realised, in terms of technical specifications and standards, in the two aforementioned categories of networks, so as to conclude to those standards that are utilized by the next generation networks (4G) which will be:
• Networks that will be unified so as the different technological platforms will function smoothly.
• Networks that will be characterized by low cost of deployment.
• The end user will be continuously connected with a wireless access network, enjoying the preferred services anywhere and anytime.
The master thesis structure follows the aforementioned methodology. The 1st Chapter includes a short presentation of expected results, both in terms of technologies and services for next generation networks, which we usually refer to as 4G networks (4th Generation) or B3G networks (Beyond 3G) or finally as All - IP wireless networks (AIPN).
In the 2nd Chapter, a detailed presentation of Mobile Telephony Networks takes place, from their first versions (1G) until the most modern (3.5G) that have been presented up to today. The analysis includes both the various generations of networks and the used standards, in terms of modulation and multiplexing techniques. The rest of the chapter focuses on the technical description of the prevailing networks, GSM, GPRS and UMTS, while the chapter ends with a short description of intersystem handover processes between GSM and UMTS.
Τhe 3rd Chapter, includes an extensive description of the Wireless Data Networks standards such as: IEEE 802.15 Wireless Personal Area Networks (WPANs) with main representatives networks based on Bluetooth and IrDA, standard IEEE 802.11 Wireless Local Area Networks (WLANs) mainly represented by WiFi and HyperLan/2, IEEE 802.16 Wireless Metropolitan Area Networks (WMANs) standard, widely known as WiMax and finally the IEEE 802.20 Wireless Wide Area Networks (WWANs) standard, namely Mobile Broadband Wireless Access (MWBA) that is still under development and aspires to constitutes the wireless version of the xDSL technology, since it aims to provide wireless broadband services.
In the 4th Chapter methodologies for integrating the two types of networks, are presented along with examples of interoperability between GPRS / UMTS and WLANs or between UMTS and WiMAX. Extensive discussion around the problems that should be faced, as the guarantee of bearable QoS level, the mechanisms for handover between the networks and the management of mobility of users and terminals, is held. Moreover, examples of integrated networks with both loose and tight coupling methodologies are presented. The last section of the chapter concerns a detailed description of architectures for interconnecting heterogeneous wireless networks over IP – based backhaul networks, namely All – IP networks, with special focus on policy based handover mechanisms and techniques for managing micromobility and macromobility issues.
The 5th Chapter concerns the changes taking place in the telecommunications market deriving from the technological progress in the subject of heterogeneous wireless networks interconnection. New service packets are created, as a result of new business plans that are drawn up by the big telecommunications organizations. Finally, we present the developments in the Greek market and subsidised projects from Information Society AE, via which wireless networks have been materialised, with aim to promote Broadband Services.
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The Inter-Domain Key Exchange Protocol / A Cryptographic Protocol for Fast, Secure Session-Key Establishment and Re-Authentication of Mobile Nodes after Inter-Domain Handovers / Das Inter-Domain-Schlüsselaustausch-Protokoll / Ein kryptographisches Protokoll zur schnellen, sicheren Session-Key-Einrichtung und erneuten Authentifizierung von mobilen Knoten nach Inter-Domain-HandovernSoltwisch, Rene Alexander 18 January 2006 (has links)
No description available.
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Überprüfung eines Serumproteinprofils für die Diagnostik von Glioblastomen / Review of a serum protein profile in the diagnosis of glioblastomaNawka, Peter 20 November 2013 (has links)
Die Diagnostik eines Glioblastoms (GBM) stützt sich z.Z. neben klinischer Symptomatik auf bildgebende Diagnostik sowie die histologische Untersuchung. In letzter Zeit werden zuneh-mend Serumproteine beschrieben und untersucht, die mit einer GBM-Erkrankung assoziiert sind. Elstner, Stockhammer und Kollegen haben 2011 ein Serumproteinprofil identifiziert, das aus CXCL10/IP-10, BMP-2 und HSP70 besteht und in einem Kollektiv von 23 GBM-Erkrankten und 9 Gesunden eine Sensitivität von 89% und eine Spezifität von 96% besaß. Dieses Profil wurde nun in einer unizentrischen klinischen Studie an 35 GBM-Erkrankten und 37 Patienten mit differenzialdiagnostisch relevanten Erkrankungen (v. a. Hirnmetastasen und primären ZNS-Lymphomen) überprüft. Dabei wurden die präoperativ abgenommenen Blut-proben mittels des ELISA-Nachweisverfahrens untersucht und die jeweiligen Konzentratio-nen in die von Elstner et al. (2011) entwickelte Regel eingesetzt. In diesem Kollektiv konnte das Profil nicht zwischen einem GBM und seinen Differenzialdiagnosen unterscheiden (Sensitivität 31%, Spezifität 54%). Es ist nicht als Hilfsmittel zur Diagnostik von Glioblastomen geeignet.
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Stochastic modeling and simulation of the TCP protocol /Olsén, Jörgen, January 1900 (has links)
Diss. (sammanfattning) Uppsala : Univ., 2003. / Härtill 6 uppsatser.
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Lasic process: um framework conceitual para integração de padrões de gestão ao desenvolvimento de projetos de propriedade intelectual de sistemas eletrônicos integrados em chips (IP-SOCS)Carvalho, Carlos Augusto Ayres 23 August 2012 (has links)
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Previous issue date: 2012-08-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work is presented as a contribution to the field of design of digital systems
integrated on chips (SoCs). Its main focus is to develop and deploy a (new)
conceptual framework for the implementation of digital integrated circuits, with a
strong emphasis on project management, called LASICProcess. As a natural
consequence of the work and serving as a proof of concept, is presented a web
application that implements the proposed framework. Among other aspects, it
presents a description of the inclusion of a formal project management layer in the
digital integrated circuits design flow used by the toolset of open and free software:
the Alliance CAD System. The application, which carries the same name as the
framework, allows the use of these tools remotely (without the need to install any
software on the client side), provides total isolation of the corporate environment with
respect to the user interface and was born with a strong vocation to become a
powerful resource for collaborative work and even the distance training of human
resources for the design of digital integrated circuits. Special care has been devoted
to showing that the set of tools used, although being developed and used primarily in
academia, provides support to all disciplines addressed and required by commercial
and industrial environments for corresponding tasks, as well as to the possibility of
(re) configuration of the proposed environment, in order to exchange all or part of the
tools ALLIANCE by its equivalent from another provider. / Este trabalho é apresentado como uma contribuição para a área de projetos de
sistemas digitais integrados em chips (SoCs). Seu foco principal é desenvolver e
implantar um (novo) framework conceitual para a implementação de circuitos
integrados digitais, com forte ênfase no gerenciamento de projetos, chamado
LASICProcess. Como consequência natural do trabalho e servindo como prova de
conceito, é apresentada uma aplicação web que implementa o framework proposto.
Entre outros aspectos, ele apresenta a descrição da inclusão de uma camada formal
de gestão de projetos no Fluxo de projeto de circuitos integrados utilizado pelo
conjunto de ferramentas do Alliance CAD System, de software aberto e livre. A
aplicação, que leva o mesmo nome do framework, permite a utilização dessas
ferramentas remotamente (sem a necessidade de instalação de nenhum software do
lado cliente), provê isolação total do ambiente corporativo com relação à interface do
usuário e nasceu com forte vocação para se tornar um potente recurso de trabalho
colaborativo e mesmo de formação a distância de recursos humanos para o projeto
de circuitos integrados digitais . Especial cuidado foi dedicado à demonstração de
que o conjunto de ferramentas utilizado, embora sendo desenvolvido e utilizado
principalmente em meio acadêmico, provê suporte a todas as disciplinas
contempladas e exigidas pelos ambientes industriais e comerciais para tarefas
correspondentes, assim como à possibilidade de (re)configuração do ambiente
proposto, para troca total ou parcial das ferramentas ALLIANCE por suas
equivalentes de outro provedor.
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Módulo IP de um Demultiplexador para o Subsistema Fluxo de Transporte- MPEG-2-Aderente ao Sistema Brasileiro de TV DigitalMedeiros, Leonardo 04 March 2010 (has links)
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Previous issue date: 2010-03-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the Brazilian scenario, the development of hardware components through
computational methodologies and tools, available at affordable costs to education and
research centers have make it feasible to design blocks and integrated circuit modules up
to intellectual property IP level, focusing strategic areas of industry, specially those
dedicated to the components for the Brazilian Digital Television System (SBTVD). This
work deals with the architectural proposal development and validation for the Transport
Stream MPEG-2 TS Subsystem of SBTVD transport stream demultiplexer from its
specification and high-level modeling to its technology mapping implementation. As
specific results, the structural and functional requirements of Transport Stream Subsystem
MPEG-2 TS are detailed, the development of a software model for the demultiplexer and
of an environment containing MPEG-2 TS flows that can validate the compliance with the
SBTVD specification of models, an RTL-level MPEG-2 TS demultiplexer IP conceptual
proof implementation and validation and its prototyping with technology mapping for FPGA
and an ASIC design kit , are also presented. / No cenário brasileiro, o desenvolvimento de componentes de hardware através de
metodologias e ferramentas computacionais, disponibilizados a custos acessíveis a
centros de ensino e pesquisa tornou factível a possibilidade de se projetar até o nível de
propriedade intelectual IP, blocos e módulos de circuitos integrados para atender áreas
estratégicas da indústria, em especial aquelas voltadas aos componentes de produtos
aderentes ao Sistema Brasileiro de Televisão Digital (SBTVD). Este trabalho trata o
desenvolvimento e validação de uma proposta arquitetural para o Subsistema de Fluxo de
Transporte MPEG-2 TS demultiplexador de fluxo de transporte do SBTVD, desde sua
especificação e modelagem em alto-nível, até sua implementação no nível de
mapeamento tecnológico. Também estão apresentados resultados específicos como o
detalhamento dos requisitos estruturais e funcionais do Subsistema de Fluxo de
Transporte MPEG-2 TS, o desenvolvimento de um modelo em software para o
demultiplexador e de um ambiente contendo fluxos MPEG-2 TS capazes de validar a
conformidade dos modelos com a especificação do SBTVD, a implementação e validação
de uma prova de conceito para um demultiplexador MPEG-2 TS no nível RTL e sua
prototipagem com mapeamento tecnológico para FPGA e para um design kit de ASIC.
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Estudo da qualidade de voz em redes IP / Study of voice quality in IP networksMagro, Julio Cesar 07 July 2005 (has links)
Orientador: Helio Waldman / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-04T21:18:47Z (GMT). No. of bitstreams: 1
Magro_JulioCesar_M.pdf: 1795144 bytes, checksum: cc5adfc75b6040f36e37ce144569c2be (MD5)
Previous issue date: 2005 / Resumo: Este trabalho descreve o estudo da qualidade de voz em redes IP a partir de uma revisão dos protocolos e mecanismos relativos a qualidade de serviço (QoS) e os aspectos do impacto sistêmico na presença ou ausência destes; revisão dos diversos métodos de avaliação da qualidade da voz com ênfase nos métodos automáticos (objetivos e repetitivos) para auxiliar na análise dos efeitos na voz dos diversos fatores presentes em uma rede de pacotes, tais como perda de pacote, atraso e jitter, bem como a própria codificação da voz em baixas taxas; revisão dos principais protocolos de sinalização utilizados para implementação de voz sobre IP (VoIP) ou telefonia sobre IP, evidenciando-se seus pontos fortes e fracos com relação a facilidade de implementação, extensibilidade e adequabilidade para várias aplicações de rede e qualidade de serviço (QoS) e realização de testes em redes IP simulada e experimental. O principal objetivo é a caracterização do serviço de voz em redes IP levando-se em consideração os efeitos dos fatores de rede e gateway no tempo de estabelecimento de uma chamada (conexão) e na qualidade da voz. Para simulação da rede IP foi utilizado o software Cloud da Shunra onde é possível tratar, de forma isolada, a influência da perda de pacote, do atraso fixo, do atraso variável (jitter), bem como do efeito conjunto da perda de pacote e jitter. Soluções a tais efeitos são investigadas em testes experimentais. Resultados de simulações sistêmicas são apresentados e discutidos. As degradações na voz devidas a tais efeitos são avaliadas e um método prático para solucionar é testado. Os resultados experimentais demonstram a viabilidade técnica da utilização da voz sobre IP (ou telefonia IP) pelos provedores de serviço, bem como pelas corporações privadas, podendo trafegar voz e dados em uma mesma rede convergente IP / Abstract: This work describes the study of voice quality in IP networks based on a revision of quality of service (QoS) protocols and mechanisms and aspects of the system impact associated with the presence or absence of them; revision of the diverse evaluation methods of voice quality with emphasis in the automatic methods (objective and repetitive) used to analyze the effects in the voice due to diverse factors presented in packet networks, such as packet loss, delay and jitter, as well as the proper voice coding at low rate; revision of the main protocols of signalling for implementation of voice over IP (VoIP) or IP telephony, considering its strong and weak points with regard to implementation facility, scalability and adequacy for some network applications and quality of service (QoS) and accomplishment of tests in simulated and experimental IP networks. The main objective is the characterization of voice service in IP networks taking into account the effect of the network factors in call set-up (connection) and in voice quality . For the simulation of the IP network the Shunra¿s Cloud software was used where it is possible to deal with, in isolated form, the influence of packet loss, fixed delay, delay variation ( jitter), as well as the composed effect of packet loss and jitter. Solutions to such effects are investigated in experimental tests. Results of system simulations are presented and discussed. Degradations in voice due to such effects are evaluated and a practical method to solve them is considered. The experimental results demonstrate the technical feasibility of using voice over IP (or IP telephony) by service providers, as well as private corporations being able to forward voice and data over the same converged IP network / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica
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