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Projektet har till syfte att undersöka den revolutionerande tekniken bakom IP-telefoni. Eftersom tekniken är relativt ung så finns det fortfarande mycket att lära om hur det fungerar och hur den används. Projektet behandlar fördelar och nackdelar samt vilka hot som finns och hur man kan känna sig säker när man använder IP-telefoni till vardags. Det primära objektivet med projektet är att få en helhetsbild och förstå hur tekniken verkligen fungerar. Vidare behandlas telefonens historia då det är viktigt att se var tekniken har sina rötter och hur den utvecklats sedan dess. Som en röd tråd från telefonens teknologi och det publika telefonnätets rötter görs en jämförelse mellan de två teknologierna för att se skillanderna och förmodade fördelar och nackdelar med de båda systemen. Olika sorters protokoll som har ett nära förhållande till IP-telefoni så som SIP, RTP, UDP och IP behandlas. För att få en sanningsenlig bild över hur vardagliga användare upplever IP-telefoni så har en enkätundersökning angående vanor och möjliga problem gjorts hos de anställda på Region Skåne.

U radu je opisana razlika između prijenosa podataka preko interneta upotrebom TCP i UD protokola.

This thesis describes the project “A new Web Server for sensors”. The project has created a demonstration web service that can receive data from sensors ( both fixed sensors and movable sensors) and distribute the received information in the form of web pages. These web pages can provide forms that enable the user to enter commands which are to be given to sensors. The aim of this thesis project was to design and evaluate web-based application which could utilize sensor data. In this project, we focused on two aspects: (1) web access to sensors and (2) the potentialmobility of sensors. The web server provides web server mediated access to the sensors. Additionally, this project examined how to integrate a sensor with a mobile device, such as a personal data appliance. The web server provides an easy acces smechanism to users who want to use and control sensors. Those users can flexibly us etheir web browser to access to sensors through our web server. Moreover, a sensor could move, for example because it is integrated with a personal data appliance. The mobility of sensors increases the sensing scope of sensors because the sensors are notfixed in position. Such sensors can sense the environment along the path that they are moved. To achieve the goals of this thesis project, we analyzed what are the basic parts and functions that should exist for sensors in the web server. Furthermore, the thesis analyzed how a sensor can be integrated with a personal data appliance, for instance,how to supply the power to sensor; and how to synchronize data between the sensor and personal data appliance. As a result of this project, a web server with some of the necessary functions was developed. An approach of how to integrate a sensor with a personal data appliance is specified in this thesis. The thesis begins with an analysis of some existing solutions. Their advantages were used to specify the requirements for our own solution. The thesis describes the design and implementation of this proposed solution. Next the thesis describes the testing and evaluation of this solution in the context of this project. The thesis ends with some conclusions and suggests future work. Denna avhandling beskriver projektet "En ny webbserver för sensorer". Projektet har skapat en tjänst demonstration nätet som kan ta emot data från sensorer (både fasta sensorer och rörliga sensorer) och distribuera fått information i form av webbsidor. Dessa webbsidor kan ge former som gör det möjligt för användaren attskriva in kommandon som ges till sensorer. Syftet med detta examensarbete var att designa och utvärdera webbaserad applikation som kan använda sensordata. I detta projekt har vi fokuserat på två aspekter: (1) webb tillgång till sensorer och (2) depotentiella rörlighet av sensorer. Webbservern ger Web Access Server förmedlas till sensorer. Dessutom undersökte detta projekt hur man kan integrera en sensor med en mobil enhet, t.ex. en personuppgifter apparat. Webbservern ger en enkel tillgång mekanism för användare som vill använda och styra sensorer. Dessa användare kanflexibelt använda sin webbläsare för att få tillgång till sensorer via vår webbserver. Dessutom kan en sensor röra sig, exempelvis genom att den är integrerad med en personuppgifter apparat. Rörligheten av sensorer ökar avkänning omfattningen av sensorer eftersom sensorerna inte är fasta på plats. Sådana sensorer kan känna miljön längs den väg som de flyttas. För att nå målen med denna avhandling projektet analyserade vi vad som är grundläggande delar och funktioner som bör finnas för sensorer i webbservern.Dessutom analyseras i avhandlingen hur en sensor kan integreras med en personuppgifterna apparat, till exempel, hur man levererar energi till sensorn, och hur man synkronisera data mellan sensorn och personuppgifter apparaten. Som ett resultatav detta projekt var en webbserver med några av de nödvändiga funktioner utvecklas.En strategi för hur man kan integrera en sensor med en personuppgifterna apparat som anges i denna avhandling. Avhandlingen inleds med en analys av några befintliga lösningar. Deras fördelar har använts för att specificera kraven för vår egen lösning. Avhandlingen beskriver utformningen och genomförandet av den föreslagna lösningen. Nästa avhandlingen beskriver testning och utvärdering av denna lösning i samband med detta projekt. Avhandlingen avslutas med några slutsatser och föreslår framtida arbete.

Günümüzde bilişim ve haberleşme hizmetleri birbirine hızla yakınlaşmakta, gelecekte bu konuların birbirinden ayrılmaz biçimde bütünleşeceği öngörülmektedir. Bu doğrultuda gelişen teknolojiyle birlikte telekom ürünlerinde de tümleşik mimari yapıların ve uygulamalara yönelik ortamların geliştirilmesi zaruri görülmektedir.IPTV teknolojisi televizyon dünyasında geleceğin teknolojisidir. Standartları halen gelişme sürecinde olup, yeni ihtiyaçlar günden güne artmaktadır. Bu durum göz önüne alındığında, en yaygın VoIP protokolü olan SIP ile IPTV sisteminin bütünleştirilmesi ihtiyacı ortaya çıkmaktadır.Bu çalışma kapsamında, SIP tabanlı çağrı sunucusuyla sağlanan telefon servislerinin IPTV sistemiyle bütünleşmesini sağlayacak yeni bir mimari yapı önerilmiş ve bu amaca yönelik yeni bir protokol tasarlanmıştır.Mevcut mimari yapıda, IPTV abonesi için bildirim kaydı, arabirim katmanında (middleware) yapılmakta ve abone bilgisi burada tutulmaktadır. Aboneye herhangi bir bildirim geldiğinde, BGY (Bildirim Geçit Yolu) bu bildirimi önce arabirim katmanına bildirmekte, arabirim katmanı da, kendisinde kayıtlı olan abone ID'sine göre ilgili STB ( Set Top Box)'a iletmekte ve STB'tan da IPTV abonesinin ekranına bildirim bilgisi gönderilmektedir. Bu mimari yapıda STB ile arabirim katmanı arasındaki iletişim TCP protokolü ile yapılmaktadır.Bu tez kapsamında yapılan geliştirmelerle, arabirim katmanına olan gereksinim ortadan kaldırılarak, bildirim mimari yapısı bir katman azaltılmaktadır. Böylece bildirim mimari yapısında donanıma olan bağımlılık sona ermekte, her türlü arabirim katmanı ile bildirim mimarisi kurulabilmektedir. Bu çalışma kapsamında geliştirilen BBP (Bağımsız Bildirim Protokolü) ile, bildirim kaydı ve gösterimi doğrudan BGY üzerinden yapılmaktadır. Geliştirilen protokol UDP protokolünü kullandığı için, STB ile BGY arasındaki iletişim UDP protokolü ile yapılmaktadır. Böylece TCP kullanan mimari yapıya kıyasla çok daha verimli bir mimari yapı elde edilmektedir.Geliştirilen mimari yapı ve protokolün testleri sonucunda, bildirim bant genişliğinin, mevcut bildirim mimari yapılara oranla onda bir oranına kadar düştüğü ve önerilen mimari yapının başarılı bir şekilde çalıştığı görülmüştür. Ayrıca çift yönlü olan (connection-oriented) TCP mesajlaşması yerine tek yönlü olan (connectionless) UDP mesajlaşmasının kullanılması, sunucu trafiğini azaltıcı yönde etki sağlamaktadır. Böylece hafıza gereksinimi olmayan daha az sunucuyla, daha düşük kapasiteli STB'larda da bildirim servisi çalışabilmektedir.Geleceğin teknolojilerinin geliştirilmesi uzun soluklu bir süreçtir. Bu tez çalışması bu sürecin sadece bir parçasıdır. Bu çalışmamın, gelecekte insanoğlunun günlük hayatının her anına girecek olan IPTV çoklu ortam iletişim ve uygulama teknolojilerinin geliştirilmesinde öncü bir çalışma olacağına inanmaktayım. Information and telecommunication services converges to each other rapidly today. In the future, these issues will not be separated from each other all the way is envisaged. In line with this emerging technology, the integrated architectural structures of telecom products and implementation environment development will be needed.IPTV technology is the future technology of TV world. Still in the process of developing standards and new requirements are increasing day by day. Given this situation, the need for integration of SIP, the most common VoIP protocol, and IPTV systems are emerging.In this thesis, new architectural structure is proposed for the purpose of converging SIP-based call server provided telephony services and IPTV system. A new protocol is also designed for this purpose.For existing architectural structure, middleware layer is scheduled for the notification registration of IPTV subscriber, and subscriber ID is kept here. When subscriber gets any notification, Notification Gateway reports the middleware first, then middleware reports related STB regarding subscriber ID and then STB forwards the notification information to the subscriber?s TV screen. In this architectural structure, STB and middleware communicates via TCP protocol.With the context of the improvements of this thesis, the notification architectural structure is reduced one layer by eliminating the need of middleware layer. Thus, the hardware dependence is ended and any middleware can be used for notification architectural structure. Through BBP protocol, developed under this study, the registration statement and notification are made directly via Notification Gateway. The developed protocol uses the UDP protocol for communication between STB and Notification Gateway. In this way, much more efficient architectural structure is obtained comparing to TCP using architectural structure.As a result of the tests for the architectural structure and the protocol developed, notification bandwidth has fallen to tenth compared to the existing architectural structure and the proposed architectural structure has been successfully running on. What?s more, using the connectionless-mode UDP transmission instead of connection oriented TCP transmission, provides a beneficial effect on reducing server traffic. Thus, the notification service can work with a fewer server having no memory and lower capacity STB.The development of future technology is a long-term process. This thesis work is only part of this process. I believe, this will be a pioneering work for development of IPTV multimedia communications and application technologies that will be in every moment of daily life of human beings in the future. 78

The adoption of the IPv6 networking in IEEE 802.15.4 sensor networks, using IEEE 1451 standardization, increases the interoperability of low-power smart sensor devices in IP networks. This paper explains the design and implementation of IPv6 over Low power Wireless Personal Area Networks (6loWPAN) and it uses the IEEE 1451 standard over IEEE 802.15.4 sensor networks. We propose an application of API IEEE 1451 that uses web services to transmit IEEE 1451 commands between Network Capable Application Processor (NCAP) and Wireless Transducer Interface Module (WTIM) using the client-server architecture. In addition the design of 6loWPAN Physical Transducer Electronic Datasheet (PHYTEDS) IEEE 1451.5 is explained. All TEDS were analyzed in terms of memory size. Each IEEE 1451 command is encapsulated in an UDP socket to establish NCAP-to-WTIM communication in an environmental monitoring application.

Routing protocol is taking a vital role in the modern communication networks. The performance of each routing protocol is different from each other. In the context of routing protocol performance, each of them has different architecture, adaptability, route processing delays and convergence capabilities. Among different routing protocols, Enhanced Interior Gateway Routing Protocol (EIGRP) and Open Shortest Path First (OSPF) have been considered as the pre-eminent routing protocols for the real-time application. EIGRP and OSPF are dynamic routing protocols used in practical networks to disseminate network topology towards the adjacent routers. There are various numbers of static and dynamic routing protocols available but it is very important to select a right protocol among them. This selection depends on several parameters such as network convergence time, network scalability and bandwidth requirements. Our thesis paper reports a simulation based comparative performance analysis between EIGRP and OSPF for real time applications such as video streaming and voice conferencing by using OPNET. In order to evaluate the performance of EIGRP and OSPF, we designed two network models that are configured with EIGRP and OSPF, respectively. The evaluation of the routing protocols is performed based on quantitative metrics such as convergence time, packet delay variation, end-to-end delay, throughput and packet loss through the simulated network models. The evaluation results show that EIGRP routing protocol provides a better performance than OSPF routing protocol for real time applications.

Els sistemes tradicionals de multiconferència disposen d'un node central que rep tots els fluxos de video dels interlocutors i que realitza una composició de tots aquests cap a un únic flux de video que serà l'enviat i visualitzat pels diferents interlocutors de la comunicació. L'objectiu d'aquest projecte resideix en crear un sistema de composició de video de n fonts, útil tant per a un sistema de multivideoconferència com per a realitzar simples composicions de video. S'adoptarà el format de video DV com a base per a la realització del sistema.

Hardware-acceleration techniques continue to be used to boost the performance of scientific codes. To do so, software developers identify portions of these codes that are amenable for offloading and map them to hardware accelerators. However, offloading such tasks to specialized hardware accelerators is non-trivial. Furthermore, these accelerators can add significant cost to a computing system. Consequently, this thesis proposes a framework called GePSeA (General Purpose Software Acceleration Framework), which uses a small fraction of the computational power on multi-core architectures to offload complex application-specific tasks. Specifically, GePSeA provides a lightweight process that acts as a helper agent to the application by executing application-specific tasks asynchronously and efficiently. GePSeA is not meant to replace hardware accelerators but to extend them. GePSeA provide several utilities called core components that offload tasks on to the core or to the special-purpose hardware when available in a way that is transparent to the application. Examples of such core components include reliable communication service, distributed lock management, global memory management, dynamic load distribution and network protocol processing. We then apply the GePSeA framework to two applications, namely mpiBLAST, an open-source computational biology application and Reliable Blast UDP (RBUDP) based file transfer application. We observe significant speed-up for both applications. Master of Science

Darbe tiriamas didelių failų perdavimo efektyvumas kliento-serverio sistemoje. Apibūdinami TCP ir UDP transportavimo lygmens protokolai, skirtingi kompiuterių sujungimo tipai – naudojant tarpinį įrenginį ir be jo. Eksperimentiniam tyrimui sukurta programinė įranga leidžianti siųsti failus: * Kliento-serverio sistema veikianti TCP protokolo pagrindu; * Kliento-serverio sistema veikianti UDP protokolo pagrindu. Eksperimentiškai nustatoma didelių failų perdavimo efektyvumo priklausomybė nuo kompiuterių sujungimo tipo, transporto lygmens protokolų bei tų protokolų parametrų. Efficiency of sending big files over networked client-server system is examined at this work. TCP and UDP transport layer protocols and different computer connection types, using intermediate device and without it, are overviewed. Software for experimental research was created: * Client-server system using TCP protocol; * Client-server system using UDP protocol. Performing experiments dependence of computer connection type, transport layer protocols ad parameter of those protocols were determined.

This paper introduce an accurate ACK-clocking model which captures the queue dynamics of links’ buffer. This is a model based on window-based protocol such as is TCP. The model presented is modeled by integral-differencial equations taking into account continuous time approach of flow rate then queue link model is derived. For bracing this derivation, packet level simulations are shown for both homogeneous and heterogeneous sources., Este trabajo presenta un modelo ACK-síncrono preciso, el cual captura la dinámica de la cola del buffer de un enlace. Este es un modelo basado en un protocolo basado en ventanas como lo es TCP. El modelo desarrollado es modelado por ecuaciones integral-diferenciales tomando en cuenta el enfoque en tiempo continuo de la tasa de flujo siendo así derivado el modelo del enlace. Para sustentar esta derivación, simulaciones a nivel de paquete son mostradas tanto para fuentes homogéneas y heterogéneas.

Xilinx-ov EDK alat u sprezi sa IwIP bibliotekom funkcija, kao i IP komponenata na raspolaganju korisniku predstavlja vrlo moćno rješenje za rješavanje niza problema vezanih za mrežnu komunikaciju sustava temeljenih na FPGA platformi. Najčešći zahtjevi su: korištenje uređaja kao zamjene za komutator, usmjerivač ili bilo koji drugi skuplji mrežni uređaj, naravno, u slučaju da je trošak razvoja funkcionalnog sustava na platformi puno manji ; udaljeni pristup uređaju u smislu kontrole nekakvog procesa sa kritičnim vremenom izvođenja (industrijska automatika, zrakoplovna navigacija, vojne primjene).

To detect network changes and network troubles, Transpondertech needs a tool that can make network measurements. The purpose of this thesis has been to find measurable network properties that best reflect the status of a network, to find methods to measure these proerties and to implement these methods in one single tool. The resulting tool is called NetworkPerf and can measure the following network properties: availability, round-trip delay, delay variation, number of hops, intermediate hosts, available bandwidth, available ports, and maximum allowed packet size. Together, these properties give a good picture of the status of a network connection. The thesis also presents the methods used for meassuring these properties in the tool.

“El funcionamiento de NAT varía de una implementación a otra. Es por lo tanto muy difícil para las aplicaciones finales predecir o descubrir el comportamiento de estos dispositivos. La predicción y el descubrimiento del funcionamiento del NAT es importante para diseñar protocolos de aplicación y técnicas de traspaso de NAT que trabajen de manera fiable en las redes existentes. Esta situación es especialmente problemática para aplicaciones extremo a extremo donde uno o ambos extremos se encuentran detrás de un NAT, como son los juegos multiusuario, aplicaciones multimedia interactivas o aplicaciones P2P.” Descripción del grupo de trabajo behave del IETF. He seleccionado como resumen del trabajo este extracto de la página Web del IETF por dos motivos. Primero, porque el desarrollo se ha basado completamente en los estudios realizados y publicados por este grupo de trabajo. Después porque en este párrafo encontramos el motivo del desarrollo del proyecto que es el de la predicción y el descubrimiento del comportamiento del NAT y la problemática que suponen este tipo de dispositivos en los nuevos usos de Internet. Como resultado del proyecto obtendremos una plataforma independiente de simulación de comunicaciones UDP a través de NAT, que permita el desarrollo de pruebas de detección y descubrimiento de NAT mediante el envío de mensajes STUN. Para ello desarrollaremos fundamentalmente tres componentes software que representen los tres elementos necesarios en este escenario, los extremos finales (el cliente y el servidor STUN) y obviamente la caja NAT. El NAT desarrollado simulará diferentes comportamientos configurables de forma que se abarque el mayor número de situaciones en las que se pueden encontrar los extremos de la comunicación. Adicionalmente, se realizarán pruebas de detección en escenarios reales utilizando el cliente STUN y los procesos de detección desarrollados para el entorno de simulación.------------------------------------------------------------------------------------------------------------------------------------------------------------- “The behavior of NATs varies from one implementation to another. As a result it is very difficult for applications to predict or discover the behavior of these devices. Predicting and/or discovering the behavior of NATs is important for designing application protocols and NAT traversal techniques that work reliably in existing networks. This situation is especially problematic for end-to-end applications where one or both end-points are behind a NAT, such as multiuser games, interactive multimedia and P2P download.” Description of working group behave of IETF. I have selected as summary of the work this extract of the web page of the IETF for two motives. First, because the development has been based completely on the studies realized and published by this group of work. Later because in this paragraph we find the motive of the development of the project that is that of the prediction and the discovery of the behavior of the NAT and the problematics that this type of devices suppose in the new uses of Internet. As result of the project we will obtain a platform independent for simulation of communications UDP across NAT, which allows the development of tests of detection and NATs discovery using the sending of messages STUN. For it we will develop fundamentally three software components that represent the three necessary elements in this scene, the final ends (the client and the server STUN) and obviously the box NAT. The developed NAT will simulate different behaviors configurables so that the major number of situations is included in those that can be the ends of the communication. Additional, tests of detection will be realized in real scenes using the client STUN and the processes of detection developed for the simulation environment. Ingeniería en Informática

Analiza uzoraka zagušenja na mrežama. Specifikacija vrsta zagušenja. Prikazati postupke i metode izbjegavanja zagušenja u paketskoj mreži. Opis značajki algoritama kontrole zagušenja kod TCP-a na klijentskoj strani. Usporedba raznih algoritama za spriječavanje zagušenja, kroz njihove prednosti i nedostatke. Prikazati utjecaj UDP paketa na TCP pakete.

This thesis is an experimental study to evaluate the performance of different routing protocols in commonly deployed scenarios. This study mainly focuses on how much time each protocol consumes while recovering from a link-loss. It provides a guide line for the best routing solutions for ISPs, individual organizations or other types of providers which are engaged in providing reliable real-time communications to their subscribers. Such communications may include vehicle trafficking data, online TV programs (IPTV), voice over IP telephony (VoIP), weather forecasts, tracking systems and many other services which totally depend upon the reliability of real-time data streams, where any major loss in received data may bring significant negative results in the integrity of the entire application. This work experimentally observes and tracks the loss of UDP packets when changes in the network topology occur. In order to make this observation in real network topologies, a custom-designed software tool has been developed. The tool is capable of delivering enough resources to a tester in evaluating the performance of routing protocols. All the test results derived from the software tool are statistically evaluated and on the basis of the outcome a better proposition can be provided to network administrators which face inconsistent topological issues.

2009, 350 p. 110 illus., Hardcover. ISBN: 978-0-387-85594-3; This chapter concerns the design of a remote control loop constituted by a Slave system (with computing and energy limitations) and a Master computer, communicating via an Internet connection. In such a situation, the communication cost is reduced but the Quality of Service of the Internet connection is not guaranteed. In particular, when the Slave dynamics are expected to be fast enough, the network induces perturbations (delays, jitters, packet dropouts and sampling) that may damage the performance. Here, the proposed solution relies on a delay-dependent, state-feedback control, computed by the Master on the basis of an observer. This last estimates the present Slave's state from its past sampled outputs, despite the various delays. Then, the computing task is concentrated in the Master. The theoretical results are based on the Lyapunov-Krasovskii functional and the approach of LMI, which guarantee the stabilization performance with respect to the expected maximum delay of the connection. Two strategies are applied: one is a constant controller/observer gain strategy, which takes into account a fixed upperbound for the communication delay. The second strategy aims at improving the performance by adapting the gains to the available network QoS (here, with two possible upperbounds).

Seminar uključuje sljedeće cjeline: glavna postaja IPTV sustava ; arhitektura IPTV mreže ; protokoli u IPTV sustavu ; višeodredišno odašiljanje u IPTV sustavu ; usluge u IPTV sustavu ; prijenosne pogreške u IPTV sustavu.

The UDP glucose-flavonoid 3-O-glucoslyltransferase (UFGT) is a key enzyme for biosynthesis and stability of anthocyanin pigments of red grapes. Understanding factors affecting expression of this enzyme is thus important for the control of grape colour. A 1640 bp promoter region of the grapevine ufgt gene was cloned and sequenced. Sequence analysis revealed seven putative ethylene-responsive cis-elements and others related to three major signals known to induce anthocyanin accumulation in plant tissues: light, sugar, and abscisic acid. In order to evaluate the ability of ethylene and other signals to drive expression from the ufgt promoter, we ran transient expression experiments using an anthocyanin-rich grape cell culture, with very low green auto-fluorescence. After biolistic bombardment, the cells were treated with various combinations of the four signals on gfp expression (green fluorescent protein). The comparison of fluorescent light intensity in cells subjected to the various treatments showed that ethylene better stimulates expression of the ufgt promoter in the dark than under light. In addition, results showed that there may be a positive interaction between ethylene and abscisic acid. This system, a promoter of interest driving the gfp expression in cells with low auto-fluorescence, may be a good tool for studies about synergistic or antagonist roles of transcription factors. Moreover, treatment of grape berries with a specific inhibitor of ethylene receptors (1-methylcyclopropene) inhibited ufgt mRNA accumulation. This confirms that the ethylene signal is likely a regulator of grape UFGT expression in a non-climacteric fruit., VITIS - Journal of Grapevine Research, Vol. 48 No. 1 (2009): Vitis

La fundació i2CAT, dins del projecte de recerca V3 (Video, Videoconferència i Visualització en HD), treballa actualment en una solució de videoconferència en Alta Definició que utilitza el software SAGE (Scalable Adaptive Graphics Environment) per visualitzar la informació que es rep en una graella de pantalles de 1200 per 1600 píxels. El rendiment actual d’aquesta part de recepció és força baix, de forma que es fa impossible la visualització de fluxos més grans de 600 Mbps. En aquest treball es detallen els resultats de l’estudi del software de visualització distribuïda SAGE i es descriu el procés d’implementació d’un nou mòdul de transmissió que utilitza el protocol de transport UDP. Tot i que l’estudi no s’ha endinsat en el tractament gràfic de l’aplicació, ha permès entendre el funcionament intern de l’aplicació i crear un model de plans i mòduls vàlid. Durant el procés de desenvolupament, s’han implementat quatre versions diferents del mòdul, utilitzant diferents estratègies i s’ha fet un estudi comparatiu amb el mòdul TCP que ja existia. Els resultats mostren que les versions amb UDP permeten enviar, com a mínim, fluxos de fins a 1’5 Gbps; suficients com per transmetre vídeos d’Alta Definició a través de la plataforma V3; no obstant que la visualització correcta de les imatges al sistema de pantalles es troba restringida a unes condicions concretes. Finalment, es proposen una sèrie d’estratègies a curt i llarg termini per acabar la implementació del mòdul.

Distribution of information across IP based networks is today part of our everyday life. IP is the backbone of the Internet and most office networks. We use IP to access web pages, listen to radio, and to create computation clusters. All these examples use bandwidth, and bandwidth is a limited resource. Many applications distribute the same information to multiple receivers, but in many cases the same information is sent to a single receiver at a time, thus multiple copies of the same information is sent, thus consuming bandwidth. What if the information could be broadcasted to all the clients at the same time, similar to a television broadcast. TCP/IP provides some means to do that. For example UDP supports broadcasting; the problem faced when using UDP is that it’s not reliable. There is no guarantee that the information actually reaches the clients. This Bachelor thesis in Computer Science aims to investigate the problems and solutions of how to achieve reliable distribution of fixed size data sets using a non reliable multicast communication channel, like UDP, in a LAN environment. The thesis defines a protocol (Almost Reliable Multicast Protocol – Arm-P) that provides maximum scalability for delivery of versioned data sets that are designed to work in a LAN-environment. A proof-of-concept application is implemented for testing purposes.

This simulator allows to construct IPv4 network topologies with routers and end hosts. The focus of the simulator is on routing table configuration. The simulator could also run user network programs written with a java.net UDP like API.

Wireless technologies in the LAN environment are becoming increasingly important. The IEEE 802.11 is the most mature technology for Wireless Local Area Networks (WLANs). The limited bandwidth and the finite battery power of mobile computers represent one of the greatest limitations of current WLANs. In this paper, we deeply investigate the efficiency and the energy consumption of MAC protocols that can be described with a p-persistent CSMA model. As already shown in the literature, the IEEE 802.11 protocol performance can be studied using a p-persistent CSMA model [12]. For this class of protocols, in the paper, we define an analytical framework to study the theoretical performance bounds from the throughput and the energy consumption standpoint. Specifically, we derive the p values (i.e., the average size of the contention window in the IEEE 802.11 protocol [12]) that maximizes the throughput, pCopt, and minimizes the energy consumption, pEopt. By providing analytical closed formulas for the optimal p values, we discuss the trade-off between efficiency and energy consumption. Specifically, we show that power saving and throughput maximization can be jointly achieved. Our analytical formulas indicate that the optimal p values depend on the network configuration, i.e., number of active stations and length of the messages transmitted on the channel. As network configurations dynamically change, the optimal p values must be dynamically updated. In this paper, we propose and evaluate a simple but effective feedback-based distributed algorithm for tuning the p parameter to the optimal values, i.e., pEopt and pCopt. The performance of the p-persistent IEEE 802.11 protocol, enhanced with our algorithm, are extensively investigated by simulation. Our results indicate that the enhanced p-persistent IEEE 802.11 protocol is very close to the theoretical bounds both in steady-state and in transient conditions.

This thesis examines the current implementations for the distribution of real-time GNSS data over IP networks such as the public Internet, focusing on two essential components of the system, data format and transport protocol. The provision of a suitable data format will allow users to take full advantage of the real-time GNSS data distribution system. Types of GNSS supported, message sizes, data rates, data precision levels, hardware and software support and possible future developments are investigated. An analysis is carried out on commonly known GNSS data formats, highlighting the most suitable standard for each evaluation criterion. A similar investigation is carried out on the transport protocols. An analysis is conducted on various design aspects of NTRIP and RT-IGS protocols, covering factors such as data latency, integrity, firewalls and proxy server compatibility and scalability. The analysis also covers the design aspects of the new draft Version 2 of NTRIP. The latter parts of this thesis report on the experiment results aimed at providing assessment of the current level of implementation of NTRIP. Data latency and integrity using NTRIP over the Internet are examined. Their impacts on users applications as the quality of real-time kinematic positioning is assessed. The results show that the performance of the system satisfies the rigorous requirement of the end-user application. The draft version of the new NTRIP indicates that UDP will be also supported. A similar investigation is carried out, providing the first experiment results on the new option. Tests using similar metrics, data latency and integrity, were carried out to verify the inherent differences between TCP and UDP. It was ascertained that, in most cases, UDP does offer improvement in terms of reduced latency over TCP. However this improvement is not significant enough to affect the performance of users applications tested. Compatibility tests were also carried out and the test results show that the new option experiences some compatibility issues with firewalls and wireless networks.

The mobile free-space optical channel mainly suffers from relatively long link outages, produced by short-term blockings of the line-of-sight (obstacles, clouds), pointing- and tracking-errors or deep signal-fades caused by index of refraction turbulence effects. This paper discusses the applicability of commonly used communication protocols like UDP, TCP, ARQ and the SCPS-TP from the Space Communications Protocol Standards (SCPS) in various scenarios. The performance of the protocols in the selected scenarios is evaluated using the simulation software OMNeT++. The simulations are based on channel measurements from the three FSO demonstrations FASOLT (61 km Ground - Ground link), KIODO (LEO satellite downlink), and ATENAA (land-mobile link) and from ongoing measurements at the German Aerospace Center (DLR) (short-range Ground - Ground) as part of the MINERVAA project. Based on the simulation results, recommendations for protocols in free-space optical communication scenarios are given.

Begreppet Voice over Internet Protocol (VoIP) är något som nog de flesta har hört talas om, men vad innebär egentligen VoIP. Vi har tittat på tekniken och återger en beskrivning av begreppet VoIP. Vi har valt att titta på hur företag använder tekniken samtidigt som vi tittar på vilka nya tjänster och möjligheter som finns. Hur ser tjänsteutbudet ut idag och hur påverkar detta sättet att kommunicera inom företagen? Vilken funktionalitet används och hur drar man nytta av de fördelar och möjligheter som den nya tekniken erbjuder? Med förändrade kommunikationssätt ser vi hur verksamheter både kan effektiviseras och utvecklas. När vi tittar på hur leverantörer bidrar till att utveckla sina kunders verksamheter så ser vi att leverantörerna inte är delaktiga inom detta område i någon större utsträckning. Vi ser dock att man inte hunnit så långt i utvecklingen av VoIP, samt att leverantörer har vissa problem med att nå ut och marknadsföra de tjänster och möjligheter den nya tekniken faktiskt erbjuder. Fokus ligger istället mer på de kostnadsbesparingar man gör genom att kommunicera över internet (IP) istället för med traditionell telefoni (PSTN). Tekniken är beroende av kvaliteten på bredbandsuppkoppling samt den interna infrastrukturen hos företagen. Mycket av de problem så som eko och dålig samtalskvalitet beror på undermålig utrustning internt på företagen. Dessa problem ser man i branschen som något övergående då ny hårdvara utvecklas och förses med bättre stöd för VoIP. Många leverantörer erbjuder även sina kunder en helhetslösning för att få kontroll över både telefoni och internetförbindelse. Slutligen ser vi att VoIP öppnar upp för en omstöpning av hur företag kommunicerar, möjligheterna har bara börjat utforskas. Som teknik är VoIP idag inget nytt, det som är nytt är att företagen först nu börjar se möjligheterna till att effektivisera, utveckla och förändra sina kommunikationsvägar. För att utfallet ska bli så bra som möjligt krävs ett helhetsgrepp på hur VoIP implementeras, vi menar att man måste se till hur man kan förändra sitt arbetssätt, inte bara hur man ringer till en lägre kostnad.

El objetivo de este proyecto es estabilizar una plataforma capaz de proveer un entorno de videoconferencia de alta calidad sobre redes IP, usando el software de UltraGrid, el cual está en estado de pruebas . En el proyecto se hace un estudio en profundidad de la transmisión en tiempo real de video DV y sin compresión (CCIR-601), para ello se realiza un estudio de la red IP y sus protocolos de transporte UDP y TCP. A lo largo del proyecto se demuestra la necesidad de usar RTP (RFC 3550) trabajando sobre UDP para el correcto funcionamiento de la transmisión en tiempo real. Se realiza un estudio del modo de encapsular el payload del RTP dependiendo del tipo de datos a transmitir. Se utiliza RFC 3189 para datos DV y RFC 4175 para la transmisión de video sin comprimir . Dichas RFC’s se demuestran en un escenario LAN mediante el software UltraGrid con pruebas de transmisión de DV a 30Mbps y video sin compresión, a 160Mbps(loopback), con su correcta reproducción en el punto de origen en tiempo real del vídeo transmitido a una alta calidad de imagen y un jiiter mínimo. En las pruebas se realiza un estudio detallado del tráfico demostrando el modo de transmisión del RTP y consiguiendo señalar cada frame enviado y como consigue sincronizar emisor y el receptor y su reordenamiento de paquetes correspondiente. Durante el proyecto , Ultragrid estuvo bajo reformas y modificaciones para su correcta adaptación en la plataforma Linux/GNU que fue instalado .Para ello fue necesario realizar un estudio sobre los sistemas Linux/GNU basados en Debian, y del lenguaje C. Todas las reformas son detalladas punto por punto en modo cronológico para que el lector comprenda el motivo de cada una de las decisiones tomadas. Como punto importante debo destacar que este trabajo me permitió estar en contacto con expertos mundiales de varios países que están a la vanguardia de la transmisión de audio y vídeo, destacando la participación del Dr. Colins Perkins y Landan Gharai de la Universidad de Glasgow y de California respectivamente. Los cuales me han expresado sus diferentes puntos de vista en cuanto a la toma de decisiones a la hora de implementar sus sistemas. Este proyecto se enmarca dentro de un proyecto de investigación de la Fundació i2cat, llamado V3 (Video, Videoconference and Visualization). Su objetivo principal es la creación de un sistema de videoconferencia en tiempo real en alta definición. El proyecto se encuentra en su fase inicial, habiendo trabajado en entornos parecidos en otros proyectos anteriores, donde el knowhow referente a la transmisión en tiempo real de flujos de alta definición ha llevado al grupo de trabajo del proyecto a decantarse por UltraGrid como software base de investigación para este entorno.

Header compression gains interest with the increasing number of short packets in the Internet, where payload length is small compared to the protocol stack header length. Compression can be applied to the whole protocol stack at once, which is referred to as "monolithic profiles" or can treat individual protocol headers separately, which is referred to as "distributed profiles". In recent ROHC activity, monolithic profiles were preferred due to the domination of RTP/UDP/IPv4 packets in the VoIP area. Considering recent development in the field of transport and network protocols, the distributed profile approach becomes of interest. In this paper, distributed profiles are proposed. Compression efficiency using monolithic and distributed profiles was tested and compared on five TCP/IP, ten RTP/UDP/IP, and five SCTP/IP flows. Monolithic profiles have generally shown somewhat better efficiency, while standalone profiles displayed better robustness when the compressor had to switch to the less efficient operating mode.

Datagram Transport Layer Security (DTLS) is a recent prococol. It provides a cryptographical layer on the top of UDP. This protocol is implemented in the OpenSSL library but its use is not documented. This document aims to show how to use this implementation, by providing examples. Datagram Transport Layer Security (DTLS) est un protocole récent qui fournit une couche cryptographique au-dessus d'UDP. Ce protocole est implémenté dans la bibliothèque OpenSSL mais son usage n'est pas documenté. Le présent document vise à montrer à l'aide d'exemples comment utiliser cette implémentation.