4 research outputs found
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
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