To provide Internet applications with good performance, the transport protocol TCP is designed to optimize the throughput of data transfers. Today, however, more and more applications rely on low latency rather than throughput. Such applications can be referred to as data-limited and are not appropriately supported by TCP. Another emerging problem is associated with the use of novel networking techniques that provide infrastructure-less networking. To improve connectivity and performance in such environments, multi-path routing is often used. This form of routing can cause packets to be reordered, which in turn hurts TCP performance. To address timeliness issues for data-limited traffic, we propose and experimentally evaluate several transport protocol adaptations. For instance, we adapt the loss recovery mechanisms of both TCP and SCTP to perform faster loss detection for data-limited traffic, while preserving the standard behavior for regular traffic. Evaluations show that the proposed mechanisms are able to reduce loss recovery latency with 30-50%. We also suggest modifications to the TCP state caching mechanisms. The caching mechanisms are used to optimize new TCP connections based on the state of old ones, but do not work properly for data-limited flows. Additionally, we design a SCTP mechanism that reduces overhead by bundling several packets into one packet in a more timely fashion than the bundling normally used in SCTP. To address the problem of packet reordering we perform several experimental evaluations, using TCP and state of the art reordering mitigation techniques. Although the studied mitigation techniques are quite good in helping TCP to sustain its performance during pure packet reordering events, they do not help when other impairments like packet loss are present. / <p>Paper V was in manuscript form at the time of the defense.</p>

This work is an introduction to the GSM system. Gives basic information about its structure, active elements, used protocols and signaling messages. It gives a propsal for structures for emulator of telephone exchange.

Les réseaux mobiles ont un modèle en couches, avec: (1) un réseau d’accès IP offrant une connectivité IP aux utilisateurs; (2) une couche de contrôle de service, l’IMS; (3) une couche d’interaction pour le contrôle des politiques réseau, le PCC. Ce modèle, centralisé et hiérarchique, serait à l’origine de problèmes de passage à l’échelle et de qualité de service en cas d’explosion du volume de trafic de données à transporter. Dans cette thèse, un nouveau modèle pour les réseaux mobiles du futur est proposé: Ultra Flat Architecture (UFA). UFA utilise l’IMS pour le contrôle de tout type d’applications. UFA est dite plate car elle réduit le nombre de types de nœuds réseau à 2 principalement: (1) une Gateway UFA regroupant à la fois l’ensemble des fonctionnalités du réseau d’accès IP, de l’IMS et du PCC; (2) le terminal. Après la conception de l’architecture, nous avons spécifié et évalué trois procédures réseau principales pour UFA : l’enregistrement/authentification, l’établissement de service et la mobilité. Nous avons optimisé les deux premières procédures par rapport aux procédures standardisées de l’IMS. Par exemple, la procédure d’établissement de service présente un délai réduit et permet une configuration du service ou de la couche de transport selon les ressources disponibles dans le réseau. Nous avons développé une procédure de mobilité pour UFA, se basant sur le transfert, d’une Gateway UFA à une autre, des contextes de toutes les couches OSI liés au terminal, et sur la détermination proactive par la Gateway UFA des paramètres de toutes les couches du terminal. Tous les résultats obtenus montrent le grand intérêt d’UFA et des architectures plates plus généralement. / Mobile networks have a layered model, with: (1) an IP access network providing IP connectivity to users, (2) a service control layer, IMS, (3) an interaction layer for policy control, PCC. This model, centralized and hierarchical, will cause scalability and QoS problems in case of data volume explosion. In this thesis, a new model for future mobile networks is proposed: Ultra Flat Architecture (UFA). UFA uses IMS to control all application types. UFA is flat since it reduces the number of network node types to 2 mainly: (1) a UFA Gateway that includes the functions of the IP access network, the IMS and the PCC, and (2) a terminal. After designing the architecture, we specified and evaluated three main procedures for UFA: registration / authentication, service establishment and mobility. We have optimized the first two procedures compared to standard procedures of the IMS. For example, the service establishment procedure has a reduced delay and allows the configuration of the service or the transport layer according to the resources available in the network. We have developed a mobility procedure for UFA. It is based on the transfer, from one UFA Gateway to another, of the all OSI-layers contexts related to that terminal, and on a proactive determination of the all OSI-layers parameters, necessary for the terminal attachment to the new UFA Gateway. All obtained results show the great interest of UFA and of flat architectures more generally.

Dans cette thèse, nous nous intéressons à la mise en œuvre de Proxy Mobile IPv6 (PMIPv6) dans les réseaux sans fil hétérogènes, dont la topologie peut être arbitraire et spontanée. Nous proposons d'abord le concept de groupe autonome ou "cluster" qui permet le passage à l'échelle des réseaux. Ensuite nous proposons des extensions à PMIPv6, appelée Scalable Proxy Mobile IPv6 (SPMIPv6), qui prennent en compte de l'architecture en clusters au travers de l'interaction entre de multiples Local Mobility Anchors (LMAs). Nous évaluons l'aptitude à supporter le passage à l'échelle de SPMIPv6 dans un contexte de réseau maillé sans fil en faisant varier sa taille, la vitesse moyenne et la densité des terminaux mobiles. En outre, nous proposons des méthodes pour l'optimisation du routage dans SPMIPv6 pour réduire les latences des communications. Nous introduisons également un mécanisme de détection de mouvements des terminaux mobiles qui prend en compte de l'hétérogénéité des technologies d'accès. Nous implémentons l'ensemble des propositions sous Linux dans un environnement virtualisé. Nous expérimentons différents scénarios dans le mode émulation ainsi qu'en vrai grandeur pour évaluer des mesures différentes telle que le coût de signalisation, la latence de handover, la perte de paquets, le temps aller-retour (RTT), et variation de débit. Finalement, nous adressons le contexte de multi-domiciliation en proposant un concept appelé virtual Stream Control Transmission Protocol (vSCTP) et l'appliquons à l'architecture PMIPv6. Les premières simulations sous Ns-2 laissent entrevoir des bénéfices pour les scénarios d'agrégation de bande passante et les scénarios d'équilibrage de charge.

In recent years, Internet and IP technologies have made inroads into almost every communication market ranging from best-effort services such as email and Web, to soft real-time applications such as VoIP, IPTV, and video. However, providing a transport service over IP that meets the timeliness and availability requirements of soft real-time applications has turned out to be a complex task. Although network solutions such as IntServ, DiffServ, MPLS, and VRRP have been suggested, these solutions many times fail to provide a transport service for soft real-time applications end to end. Additionally, they have so far only been modestly deployed. In light of this, this thesis considers transport protocols for soft real-time applications. Part I of the thesis focuses on the design and analysis of transport protocols for soft real-time multimedia applications with lax deadlines such as image-intensive Web applications. Many of these applications do not need a completely reliable transport service, and to this end Part I studies so-called partially reliable transport protocols, i.e., transport protocols that enable applications to explicitly trade reliability for improved timeliness. Specifically, Part I investigates the feasibility of designing retransmission-based, partially reliable transport protocols that are congestion aware and fair to competing traffic. Two transport protocols are presented in Part I, PRTP and PRTP-ECN, which are both extensions to TCP for partial reliability. Simulations and theoretical analysis suggest that these transport protocols could give a substantial improvement in throughput and jitter as compared to TCP. Additionally, the simulations indicate that PRTP-ECN is TCP friendly and fair against competing congestion-aware traffic such as TCP flows. Part I also presents a taxonomy for retransmission-based, partially reliable transport protocols. Part II of the thesis considers the Stream Control Transmission Protocol (SCTP), which was developed by the IETF to transfer telephony signaling traffic over IP. The main focus of Part II is on evaluating the SCTP failover mechanism. Through extensive experiments, it is suggested that in order to meet the availability requirements of telephony signaling, SCTP has to be configured much more aggressively than is currently recommended by IETF. Furthermore, ways to improve the transport service provided by SCTP, especially with regards to the failover mechanism, are suggested. Part II also studies the effects of Head-of-Line Blocking (HoLB) on SCTP transmission delays. HoLB occurs when packets in one flow block packets in another, independent, flow. The study suggests that the short-term effects of HoLB could be substantial, but that the long-term effects are marginal.

Ce travail de thèse aborde les problématiques de coopération de réseaux hétérogènes et de leurs exploitations par un terminal multi-interfaces en situation de mobilité. Le phénomène de convergence des services vers un support unique place le protocole IP comme moyen de communication universel pour le transport de l'information. Cependant, le modèle TCP/IP actuel ne permet pas d'exploiter simultanément, et efficacement, les différentes connexions radio (UMTS, 802.11, DVB) potentiellement disponibles auprès d'un terminal.<br />Nous avons réalisé un état de l'art, mettant en exergue les insuffisances des solutions actuelles, et nous permettant de définir les modes de coopération de<br />réseaux. Nous proposons ici une nouvelle architecture protocolaire reposant sur les protocoles IPv6 et SCTP, et intégrant une entité de gestion des différents réseaux afin d'obtenir une coopération de réseaux optimisée pour un service donné. A travers une expérimentation et diverses simulations, nous avons pu évaluer, par partie, les performances du modèle proposé.

With the deployment of 3G networks and gradual implementation of wireless networks, seamless handover between these wireless networks is becoming an increasingly desirable. mSCTP (Mobile Stream Control Transmission Protocol) is a new protocol developed from SCTP (Stream Control Transmission Protocol) to provide seamless handover based on IP networks. This thesis studies how to use this new protocol to handle handovers on transport level between CDMA2000 and WLAN networks. A survey of recently proposed and used mobility protocols is presented, comparing three common handover protocols operating on different layers: MIP (mobile IP) for the network layer, mSCTP for the transport layer and SIP (Session Initial Protocol) for the session layer. The results show mSCTP is the future for mobility support. Lastly, I will present a detailed procedure on how to set up handover testbed between CDMA2000 network and 802.11 WLAN based on mSCTP and the results show that the handover performed between these two networks is fast and smooth but it is affected by the signal strength of the CDMA2000.

Diploma thesis deals with creation of laboratory exercises in ns-3 environment. Each one of three exercises consists of theoretical introduction and instructions to carry out the simulation. The first exercise´s topic is routing protocol BGP. The second exercise is focused on transport protocols TCP, UDP, SCTP. In the last exercise, the basic network devices and topologies are simulated. The ARP and RIPv2 protocols are simulated as well.

This thesis attempts to provide basic overview of the topic of the GSM system and tries to design Mobile Switching Centre Emulator that could perform the operation Location Update. The first part of this thesis describes the principles and specifics of the GSM network (network structure, the operations required to support user mobility, network entities, etc.). The second part of this thesis describes the SS7 signaling protocols, SIGTRAN and MAP protocol. The final part deals with design of the emulator.

This diploma thesis focuses on theoretical and practical comparison of webpage transport protocols such as HTTP/HTTPS (Hypertext Transfer Protocol) v1.1, SPDY, HTTP/2 and QUIC using UDP (User Datagram Protocol), TCP (Transmission Control Protocol) and SCTP (Stream Control Transmission Protocol) as transport protocols. This work also contains design and manual for practical laboratory tasks on which can students verify theoretical assumptions. These tasks compares protocols in different conditions such as packet loss, latency and jitter.