Mobility prediction and multicasting in wireless networks : performance and analysis

Handoff is a call handling mechanism that is invoked when a mobile node moves from one cell to another. Such movement may lead to degradation in performance for wireless networks as a result of packet losses. A promising technique proposed in this thesis is to apply multicasting techniques aided by mobility prediction in order to improve handoff performance. In this thesis, we present a method that uses a Grey model for mobility prediction and a fuzzy logic controller that has been fine-tuned using evolutionary algorithms in order to improve prediction accuracy. We also compare the self-tuning algorithm with two evolutionary algorithms in terms of accuracy and their convergence times. Our proposed method takes into account signal strengths from the base stations and predicts the signal strength of the next candidate base station in order to provide improved handover performance. The primary decision for mobility prediction is the accurate prediction of signal strengths obtained from the base stations and remove any unwanted errors in the prediction using suitable optimisation techniques. Furthermore, the model includes the procedures of fine-tuning the predicted data using fuzzy parameters. We also propose suitable multicasting algorithms to minimise the reservation of overall network resource requirements during handoff with the mobility prediction information. To be able to efficiently solve the problem, the situation is modelled using a multicast tree that is defined to maintain connectivity with the mobile node, whilst ensuring bandwidth guarantees and a minimum hop-count. In this approach, we have tried to solve the problem by balancing two objectives through putting a weight on each of two costs. We provide a detailed description of an algorithm to implement join and prune mechanisms, which will help to build an optimal multicast tree with QoS requirements during handoff as well as incorporating dynamic changes in the positions of mobile nodes. An analysis of how mobility prediction helps in the selection of potential Access Routers (AR) with QoS requirements - which affects the multicast group size and bandwidth cost of the multicast tree -- is presented. The proposed technique tries to minimise the number of multicast tree join and prune operations. Our results show that the expected size of the multicast group increases linearly with an increase in the number of selected destination AR's for multicast during handoff. We observe that the expected number of joins and prunes from the multicast tree increases with group size. A special simulation model was developed to demonstrate both homogeneous and heterogeneous handoff which is an emerging requirement for fourth generation mobile networks. The model incorporates our mobility prediction model for heterogeneous handoff between the Wireless LAN and a cellular network. The results presented in this thesis for mobility prediction, multicasting techniques and heterogeneous handoff include proposed algorithms and models which aid in the understanding, analysing and reducing of overheads during handoff

Exploiting user contention to optimize proactive resource allocation in future networks

In order to provide ubiquitous communication, seamless connectivity is now required in all environments including highly mobile networks. By using vertical handover techniques it is possible to provide uninterrupted communication as connections are dynamically switched between wireless networks as users move around. However, in a highly mobile environment, traditional reactive approaches to handover are inadequate. Therefore, proactive handover techniques, in which mobile nodes attempt to determine the best time and place to handover to local networks, are actively being investigated in the context of next generation mobile networks. The Y-Comm Framework which looks at proactive handover techniques has de�fined two key parameters: Time Before Handover and the Network Dwell Time, for any given network topology. Using this approach, it is possible to enhance resource management in common networks using probabilistic mechanisms because it is now possible to express contention for resources in terms of: No Contention, Partial Contention and Full Contention. As network resources are shared between many users, resource management must be a key part of any communication system as it is needed to provide seamless communication and to ensure that applications and servers receive their required Quality-of-Service. In this thesis, the contention for channel resources being allocated to mobile nodes is analysed. The work presents a new methodology to support proactive resource allocation for emerging future networks such as Vehicular Ad-Hoc Networks (VANETs) by allowing us to calculate the probability of contention based on user demand of network resources. These results are veri�ed using simulation. In addition, this proactive approach is further enhanced by the use of a contention queue to detect contention between incoming requests and those waiting for service. This thesis also presents a new methodology to support proactive resource allocation for future networks such as Vehicular Ad-Hoc Networks. The proposed approach has been applied to a vehicular testbed and results are presented that show that this approach can improve overall network performance in mobile heterogeneous environments. The results show that the analysis of user contention does provide a proactive mechanism to improve the performance of resource allocation in mobile networks

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

On distributed mobile edge computing

Mobile Cloud Computing (MCC) has been proposed to offload the workloads of mobile applications from mobile devices to the cloud in order to not only reduce energy consumption of mobile devices but also accelerate the execution of mobile applications. Owing to the long End-to-End (E2E) delay between mobile devices and the cloud, offloading the workloads of many interactive mobile applications to the cloud may not be suitable. That is, these mobile applications require a huge amount of computing resources to process their workloads as well as a low E2E delay between mobile devices and computing resources, which cannot be satisfied by the current MCC technology. In order to reduce the E2E delay, a novel cloudlet network architecture is proposed to bring the computing and storage resources from the remote cloud to the mobile edge. In the cloudlet network, each mobile user is associated with a specific Avatar (i.e., a dedicated Virtual Machine (VM) providing computing and storage resources to its mobile user) in the nearby cloudlet via its associated Base Station (BS). Thus, mobile users can offload their workloads to their Avatars with low E2E delay (i.e., one wireless hop). However, mobile users may roam among BSs in the mobile network, and so the E2E delay between mobile users and their Avatars may become worse if the Avatars remain in their original cloudlets. Thus, Avatar handoff is proposed to migrate an Avatar from one cloudlet into another to reduce the E2E delay between the Avatar and its mobile user. The LatEncy aware Avatar handDoff (LEAD) algorithm is designed to determine the location of each mobile user\u27s Avatar in each time slot in order to minimize the average E2E delay among all the mobile users and their Avatars. The performance of LEAD is demonstrated via extensive simulations. The cloudlet network architecture not only facilitates mobile users in offloading their computational tasks but also empowers Internet of Things (IoT). Popular IoT resources are proposed to be cached in nearby brokers, which are considered as application layer middleware nodes hosted by cloudlets in the cloudlet network, to reduce the energy consumption of servers. In addition, an Energy Aware and latency guaranteed dynamic reSourcE caching (EASE) strategy is proposed to enable each broker to cache suitable popular resources such that the energy consumption from the servers is minimized and the average delay of delivering the contents of the resources to the corresponding clients is guaranteed. The performance of EASE is demonstrated via extensive simulations. The future work comprises two parts. First, caching popular IoT resources in nearby brokers may incur unbalanced traffic loads among brokers, thus increasing the average delay of delivering the contents of the resources. Thus, how to balance the traffic loads among brokers to speed up IoT content delivery process requires further investigation. Second, drone assisted mobile access network architecture will be briefly investigated to accelerate communications between mobile users and their Avatars

Evaluating Next Cell Predictors with Extensive Wi-Fi Mobility Data

Location is an important feature for many applications, and wireless networks can better serve their clients by anticipating client mobility. As a result, many location predictors have been proposed in the literature, though few have been evaluated with empirical evidence. This paper reports on the results of the first extensive empirical evaluation of location predictors, using a two-year trace of the mobility patterns of over 6,000 users on Dartmouth\u27s campus-wide Wi-Fi wireless network. The surprising results provide critical evidence for anyone designing or using mobility predictors. \par We implemented and compared the prediction accuracy of several location predictors drawn from four major families of domain-independent predictors, namely Markov-based, compression-based, PPM, and SPM predictors. We found that low-order Markov predictors performed as well or better than the more complex and more space-consuming compression-based predictors

Chapter Evaluation of QoS and QoE in Mobile WIMAX – Systematic Approach

Space scienc