Mobility management in IP-Based Networks

Mobile communication networks experience a tremendous development clearly evident from the wide variety of new applications way beyond classical phone services. The tremendous success of the Internet along with the demand for always-on connectivity has triggered the development of All-IP mobile communication networks. Deploying these networks requires, however, overcoming many challenges. One of the main challenges is how to manage the mobility between cells connecting through an IP core in a way that satisfies real-time requirements. This challenge is the focus of this dissertation. This dissertation delivers an in-depth analysis of the mobility management issue in IP-based mobile communication networks. The advantages and disadvantages of various concepts for mobility management in different layers of the TCP/IP protocol stack are investigated. In addition, a classification and brief description of well-known mobility approaches for each layer are provided. The analysis concludes that network layer mobility management solutions seem to be best suited to satisfy the requirements of future All-IP networks. The dissertation, therefore, provides a comprehensive review of network layer mobility management protocols along with a discussion of their pros and cons. Analyses of previous work in this area show that the proposed techniques attempt to improve the performance by making constraints either on access networks (e.g. requiring a hierarchical topology, introducing of intermediate nodes, etc.) or mobile terminals (e.g. undertaking many measurements, location tracking, etc.). Therefore, a new technique is required that completes handoffs quickly without affecting the end-to-end performance of ongoing applications. In addition, it should place restrictions neither on access networks nor on mobiles. To meet these requirements, a new solution named Mobile IP Fast Authentication protocol (MIFA) is proposed. MIFA provides seamless mobility and advances the state of the art. It utilizes the fact that mobiles movements are limited to a small set of neighboring subnets. Thus, contacting these neighbors and providing them in advance with sufficient data related to the mobiles enable them to fast re-authenticate the mobiles after the handoff. The dissertation specifies the proposal for both IPv4 and IPv6. The specification of MIFA considers including many error recovery mechanisms to cover the most likely failures. Security considerations are studied carefully as well. MIFA does not make any restrictions on the network topology. It makes use of layer 2 information to optimize the performance and works well even if such information is not available.In order to analyze our new proposal in comparison to a wide range of well-known mobility management protocols, this dissertation proposes a generic mathematical model that supports the evaluation of figures such as average handoff latency, average number of dropped packets, location update cost and packet delivery cost. The generic model considers dropped control messages and takes different network topologies and mobility scenarios into account. This dissertation also validates the generic mathematical model by comparing its results to simulation results as well as results of real testbeds under the same assumptions. The validation proves that the generic model delivers an accurate evaluation of the performance in low-loaded networks. The accuracy of the model remains acceptable even under high loads. The validation also shows that simulation results lie in a range of 23 %, while results of real testbeds lie in a range of 30 % of the generic model?s results. To simplify the analysis using the generic mathematical model, 4 new tools are developed in the scope of this work. They automate the parameterization of mobility protocols, network topologies and mobility scenarios. This dissertation also evaluates the new proposal in comparison to well-known approaches (e.g. Mobile IP, Handoff-Aware Wireless Access Internet Infrastructure (HAWAII), etc.) by means of the generic mathematical model as well as simulation studies modeled in the Network Simulator 2. The evaluation shows that MIFA is a very fast protocol. It outperforms all studied protocols with respect to the handoff latency and number of dropped packets per handoff. MIFA is suitable for low as well as high speeds. Moreover, there is no significant impact of the network topology on its performance. A main advantage of MIFA is its robustness against the dropping of control messages. It remains able to achieve seamless handoffs even if a dropping occurs. The performance improvement is achieved, however, at the cost of introducing new control messages mainly to distribute data concerning mobile terminals to neighbor subnets. This results in more location update cost than that resulting from the other mobility management protocols studied. Due to excluding any constraints on the network topology, MIFA generates the same packet delivery cost as Mobile IP and less than other protocols.An additional focus of this dissertation is the development of an adaptive eLearning environment that personalizes eLearning contents conveying the topics of this dissertation depending on users? characteristics. The goal is to allow researchers to quickly become involved in research on mobility management, while learners such as students are able to gain information on the topics without excess detail. Analyses of existing eLearning environments show a lack of adaptivity support. Existing environments focus mainly on adapting either the navigation or the presentation of contents depending on one or more selected users? characteristics. There is no environment that supports both simultaneously. In addition, many user characteristics are disregarded during the adaptivity process. Thus, there is a need to develop a new adaptive eLearning environment able to eliminate these drawbacks. This dissertation, therefore, designs a new Metadata-driven Adaptive eLearning Environment (MAeLE). MAeLE generates personalized eLearning courses along with building an adequate navigation at run-time. Adaptivity depends mainly on providing contents with their describing metadata, which are stored in a separate database, thus enabling reusing of eLearning contents. The relation between the metadata that describe contents and those describing learners are defined accurately, which enables a dynamic building of personalized courses at run-time. A prototype for MAeLE is provided in this dissertation as well

QoS-aware Mobility Management in IP-based Communication Networks

Der allgegenwärtige Zugang zu Informationen, jederzeit und überall, ist ein wichtiges Merkmal künftiger All-IP-Mobilfunktnetze, die verschiedene Systeme miteinander verbinden, dabei dynamischer und flexibler sein werden. Der Einsatz dieser Netze erfordert es jedoch, viele Herausforderungen zu überwinden. Eine der wichtigsten im Rahmen dieser Arbeit, ist die Frage, wie Quality of Service (QoS) Eigenschaften in solchen hoch dynamischen, mobilen Umgebungen zu garantieren sind. Bekanntermaßen beeinflusst die Mobilität von Mobilknoten (MN) die Dienstgüte in mobilen Netzen, da QoS-Parameters für die Ende-zu-Ende-Kommunikation vereinbart werden. Daher müssen Lösungen entwickelt werden, die nahtlose Mobilität, bei gleichzeitigen QoS-Garantien nach Handoffs, unterstützen. Diese Herausforderung ist das Hauptziel der vorliegenden Dissertation, die einen umfassenden Überblick über die bestehenden Mobilitäts- und QoS-Managment-Lösungen in IP-basierten Netzen liefert, gefolgt von einem Einblick in Methoden zur Kopplung von Mobilitätsmanagement und QoS-Lösungen. Nach Betrachtung der Vor- und Nachteile bestehender Ansätze, kommt die Dissertation zu dem Schluss, dass hybride Strategien vielversprechend sind und zu praktikablen Lösungen weiterentwickelt werden können, die sowohl Mobilitäts- als auch QoS-Anforderungen auf effiziente Weise,in allen zukünftigen IP-Mobilfunknetzen erfüllen können. Auf dieser Grundlage schlägt die Dissertation ein neues Hybrid-Protokoll, genannt "QoS-aware Mobile IP Fast Authentication Protocol" (QoMIFA), vor. Unser Vorschlag integriert MIFA als Mobilitäts-Management-Protokoll mit RSVP als QoS Reservierungsprotokoll. MI-FA wird aufgrund seiner Fähigkeit zu schnellen, sicheren und robusten Handoffs gewählt. RSVP hingegen dient als Standardlösung zur Bereitstellung von QoS in bestehenden IP-basierten Netzen. Unter Einhaltung der Hybrid-Architektur wird RSVP um ein neues Objekt, genannt "Mobility Object" erweitert, welches MIFA-Kontrollnachrichten kapselt. Nach der Spezifikation des neuen Vorschlags, bewertet die Dissertation auch seine Leistung im Vergleich zu dem bekannten "Simple QoS Signaling Protocol" (Simple QoS), mittels Simulationsstudien, modelliert mit dem "Network Simluator 2" (NS2). In der Auswertung werden der Einflusses der Netzwerklast und der Geschwindigkeit des Mobilknotens untersucht. Die hierzu verwendeten Leistungsparameter umfassen die Ressourcen-Reservierungs-Latenz, die Anzahl verlorener Pakete pro Handoff, die Anzahl der, vor Abschluss der Reservierung, mit Best-Effort-Eigenschaften übertragenen Pakete pro Handoff und die Wahrscheinlichkeit von Verbindungsabbrüchen. Unsere mittels Simulation erzielten Ergebnisse zeigen, dass QoMIFA schnelle und nahtlose Handoffs mit schneller Ressourcenreservierung nach Handoffs kombinieren kann. Unter Berücksichtigung des Einflusses der Netzwerklast, ist nachweisbar, dass QoMIFA eine besser Leistung als Simple QoS in allen untersuchten Szenarien mit geringer, mittlerer und hoher Last erreicht. Bei Betrachtung des Einflusses der Bewegungsgeschwindigkeit des Mobilknotens auf die Leistung, lassen sich unter beiden Protokollen Ping-Pong-Effekte beobachten, welche zu höheren Ressourcen-Reservierungs-Latenzen, mehr verlorenen Paketen und mehr Best-Effort-Paketen pro Handoff bei geringeren Geschwindigkeiten führen. Der stärkste Einfluss dieser Pinp-Pong-Effekte ist jeweils bei 3 km/h zu beobachten. Allerdings verhält sich QoMIFA unter allen untersuchten Bewegungsgeschwindigkeiten besser als Simple QoS und kann Mobilknoten auch bei hohen Geschwindigkeiten bedienen. In Anschluss an die simulationsgestützte Evaluierung, schätzt die Dissertation die Signalisierungskosten beider Protokolle unter Betrachtung der Kosten für Ortslokalise-rung und Paketzustellung. Im Ergebnis erreicht QoMIFA die zuvor genannten Leistungsverbesserungen auf Kosten von größeren Ortslokalisierungskosten und leicht höherer Paketzustellungskosten.Ubiquitous access to information anywhere, anytime and anyhow is an important feature of future all-IP mobile communication networks, which will interconnect various systems and be more dynamic and flexible. The deployment of these networks, however, requires overcoming many challenges. One of the main challenges of interest for this work is how to provide Qual-ity of Service (QoS) guarantees in such highly dynamic mobile environments.As known, mobility of Mobile Nodes (MNs) affects the QoS in mobile networks since QoS parameters are made for end-to-end communications. Therefore, it is a challenge to develop new solutions capable of supporting seamless mobility while simultaneously providing QoS guarantees after handoffs. Addressing this challenge is the main objective of this dissertation, which provides a comprehensive overview of mobility management solutions and QoS mech-anisms in IP-based networks followed by an insight into how mobility management and QoS solutions can be coupled with each other. Following the highlight of the state of art along with the pros and cons of existing approaches, the dissertation concludes that hybrid strategies are promising and can be further developed to achieve solutions that are capable of simultaneous-ly supporting mobility and QoS, simple from the implementation point of view, efficient and applicable to future all-IP mobile communication networks.Based on this, the dissertation proposes a new hybrid proposal named QoS-aware Mobile IP Fast Authentication Protocol (QoMIFA). Our proposal integrates MIFA as a mobility man-agement protocol with RSVP as a QoS reservation protocol. MIFA is selected due to its capa-bility of the provision of fast, secure and robust handoffs, while RSVP is chosen because it presents the standard solution used to support QoS in existing IP-based networks. The hybrid architecture is retained by introducing a new object, called “mobility object”, to RSVP in or-der to encapsulate MIFA control messages.Following the specification of the new proposal, the dissertation also evaluates its perfor-mance compared to the well-known Simple QoS signaling protocol (Simple QoS) by means of simulation studies modeled using the Network Simulator 2 (NS2). The evaluation compris-es the investigation of the impact of network load and MN speed. The performance measures we are interested in studying comprise the resource reservation latency, number of dropped packets per handoff, number of packets sent as best-effort per handoff until the reservation is accomplished and probability of dropping sessions. Our simulation results show that QoMIFA is capable of achieving fast and smooth handoffs in addition to its capability of quickly re-serving resources after handoffs. Considering the impact of network load, QoMIFA outper-forms Simple QoS in all studied scenarios (low- , middle- and high-loaded scenarios). With respect to the impact of MN speed, it can be observed that the impact of ping-pong effects is seen with both protocols and results in higher resource reservation latency, more dropped packets per handoff and more best-effort packets per handoff at low speeds than at higher ones. The worst impact of ping-pong effects is seen at a speed of 3 km/h when employing QoMIFA and Simple QoS, respectively. However, QoMIFA remains performing significantly better than Simple QoS under all studied MN speeds and can even properly serve MNs mov-ing at high speeds.Following the simulative evaluation, the dissertation estimates the signaling cost of both stud-ied protocols with respect to the location update and packet delivery cost. Our results show that QoMIFA achieves the above mentioned performance improvements at the cost of greater location update cost and slightly higher packet delivery cost than Simple QoS