Στην εν λόγω εργασία, έγινε μια προσπάθεια καταγραφής του τεχνολογικού τοπίου της τηλεπικοινωνιακής αγοράς, με έμφαση την διαλειτουργικότητα μεταξύ των Δικτύων Κινητής Τηλεφωνίας και των Ασύρματων Δικτύων Δεδομένων και των σχετικών αλλαγών που έχει επιφέρει αυτή η διαλειτουργικότητα, τόσο στις παρεχόμενες υπηρεσίες, όσο και στα εφαρμοζόμενα επιχειρηματικά μοντέλα από πλευράς εταιρειών της συγκεκριμένης αγοράς. Στα πλαίσια αυτής της προσπάθειας, χρειάστηκε να πραγματοποιηθεί μια λεπτομερής καταγραφή των τεχνολογικών εξελίξεων, σε επίπεδο τεχνικών προδιαγραφών και προτύπων, στις παραπάνω δύο κατηγορίες δικτύων, ώστε να καταλήξουμε σε εκείνα τα πρότυπα που πλέον μπορούν να οδηγήσουν στην υλοποίηση δικτύων τα οποία θα χαρακτηρίζονται από τα παρακάτω: • θα είναι ενοποιημένα ώστε οι διαφορετικές τεχνολογικές πλατφόρμες των εταιρειών να λειτουργούν απρόσκοπτα, • θα χαρακτηρίζονται από χαμηλό κόστος, • ο τελικός χρήστης θα μπορεί να είναι συνεχώς συνδεδεμένος με κάποιο δίκτυο ασύρματης πρόσβασης και να απολαμβάνει τις υπηρεσίες που επιθυμεί, οποτεδήποτε και οπουδήποτε. Η δομή της διπλωματικής εργασίας ακολουθεί τον προαναφερθέντα τρόπο σκέψης. Στο 1ο Κεφάλαιο γίνεται μια σύντομη παρουσίαση του στόχου σε επίπεδο τεχνολογιών αλλά και υπηρεσιών, δηλαδή των αναμενόμενων αποτελεσμάτων αυτών των δικτύων νέας γενιάς, στα οποία έχουμε συνηθίσει να αναφερόμαστε ως δίκτυα 4G (4th Generation) ή δίκτυα B3G (Beyond 3G) ή τέλος ως All – IP ασύρματα δίκτυα. Στο 2ο Κεφάλαιο, γίνεται μια λεπτομερής παρουσίαση των Δικτύων Κινητής Τηλεφωνίας από τις πρώτες τους εκδοχές (1G) έως τις πλέον σύγχρονες (3.5G) που έχουν εμφανιστεί μέχρι σήμερα. Αναλύονται τόσο οι γενιές των δικτύων όσο και τα χρησιμοποιούμενα πρότυπα, σε επίπεδο αρχιτεκτονικής όσο και σε επίπεδο πρωτοκόλλων. Στη συνέχεια του κεφαλαίου υπάρχει η τεχνική περιγραφή των επικρατέστερων δικτύων κινητής τηλεφωνίας, σήμερα, δηλαδή των GSM, GPRS και UMTS, ενώ στο τέλος του κεφαλαίου υπάρχει μια σύντομη περιγραφή της διαδικασίας intersystem handover μεταξύ των GSM και UMTS. Στο 3ο Κεφάλαιο, περνάμε πλέον στα Ασύρματα Δίκτυα Δεδομένων. Γίνεται μια εκτενής περιγραφή των προτύπων που έχουν καθοριστεί και συγκεκριμένα στα πρότυπα IEEE 802.15 Wireless Personal Area Networks (WPANs) με κυριότερους εκφραστές τα δίκτυα βασιζόμενα σε Bluetooth και IrDA, το πρότυπο IEEE 802.11 Wireless Local Area Networks (WLANs) με σημαντικότερος εκπροσώπους τα WiFi και HyperLan/2, το πρότυπο IEEE 802.16 Wireless Metropolitan Area Networks (WMANs) ή αλλιώς γνωστότερο ως WiMAX και τέλος το πρότυπο IEEE 802.20 Wireless Wide Area Networks (WWANs) ή διαφορετικά Mobile Broadband Wireless Access (MWBA) το οποίο είναι υπό διερεύνηση ακόμα και φιλοδοξεί να αποτελέσει το ασύρματο ανάλογο της τεχνολογίας xDSL, καθώς θα προσφέρει ασύρματες ευρυζωνικές υπηρεσίες. Στο 4ο Κεφάλαιο παρουσιάζονται μεθοδολογίες υλοποίησης του integration μεταξύ δικτύων των δύο κατηγοριών και συγκεκριμένα παραδείγματα διαλειτουργικότητας, όπως μεταξύ GPRS ή UMTS και WLANs ή μεταξύ UMTS και WiMAX. Γίνεται εκτενής συζήτηση γύρω από τα προβλήματα που θα πρέπει να αντιμετωπιστούν, όπως η εξασφάλιση ανεκτού επιπέδου QoS, οι μηχανισμοί για handover μεταξύ των δικτύων, η διαχείριση της κινητικότητας των χρηστών και των τερματικών και δίνονται παραδείγματα δημιουργίας ενοποιημένων δικτύων, τόσο με τη τεχνική της χαλαρής όσο και με την τεχνική της ισχυρής ζεύξης. Στο τελευταίο τμήμα του Κεφαλαίου, γίνεται μια εκτενής αναφορά στις αρχιτεκτονικές διασύνδεσης ετερογενών δικτύων με IP δίκτυα κορμού, τα γνωστά All – IP networks. Ιδιαίτερη έμφαση δίνεται στους μηχανισμούς πραγματοποίησης των handovers βάσει πολιτικών (policy based) και η χρήση τεχνικών για micromobility και macromobility σε σχέση με την κινητικότητα των τερματικών. Το 5ο Κεφάλαιο αφορά τις εφαρμογές και υλοποιήσεις ασυρμάτων δικτύων δεδομένων στον Ελληνικό χώρο, στα πλαίσια του Επιχειρησιακού Προγράμματος «Κοινωνία της Πληροφορίας» και πιο συγκεκριμένα τα «Εξοπλισμός και δικτύωση σε όλες τις βαθμίδες της εκπαίδευσης», «Ασύρματα Ευρυζωνικά Δίκτυα ΟΤΑ»και «Μητροπολιτικά Ευρυζωνικά Δίκτυα Οπτικών Ινών ΟΤΑ» και ουσιαστικά αποτελούν παραδείγματα και υλοποιήσεις διασύνδεσης WiFi, WiMAX και IP backbone δικτύων όπως το ΣΥΖΕΥΞΙΣ με δυνατότητες για παροχή VoIP. / In this thesis, an effort of presenting the technological landscape of the telecommunication market takes place, with focus on the interoperability between the Mobile Telephony Networks and the Wireless Data Networks and the relative changes that have evolved through this interoperability, both regarding the provided services and the applied business models by the enterprises of the specific market. Within the frames of this effort, a detailed recording of technological developments is realised, in terms of technical specifications and standards, in the two aforementioned categories of networks, so as to conclude to those standards that are utilized by the next generation networks (4G) which will be: • Networks that will be unified so as the different technological platforms will function smoothly. • Networks that will be characterized by low cost of deployment. • The end user will be continuously connected with a wireless access network, enjoying the preferred services anywhere and anytime. The master thesis structure follows the aforementioned methodology. The 1st Chapter includes a short presentation of expected results, both in terms of technologies and services for next generation networks, which we usually refer to as 4G networks (4th Generation) or B3G networks (Beyond 3G) or finally as All - IP wireless networks (AIPN). In the 2nd Chapter, a detailed presentation of Mobile Telephony Networks takes place, from their first versions (1G) until the most modern (3.5G) that have been presented up to today. The analysis includes both the various generations of networks and the used standards, in terms of modulation and multiplexing techniques. The rest of the chapter focuses on the technical description of the prevailing networks, GSM, GPRS and UMTS, while the chapter ends with a short description of intersystem handover processes between GSM and UMTS. Τhe 3rd Chapter, includes an extensive description of the Wireless Data Networks standards such as: IEEE 802.15 Wireless Personal Area Networks (WPANs) with main representatives networks based on Bluetooth and IrDA, standard IEEE 802.11 Wireless Local Area Networks (WLANs) mainly represented by WiFi and HyperLan/2, IEEE 802.16 Wireless Metropolitan Area Networks (WMANs) standard, widely known as WiMax and finally the IEEE 802.20 Wireless Wide Area Networks (WWANs) standard, namely Mobile Broadband Wireless Access (MWBA) that is still under development and aspires to constitutes the wireless version of the xDSL technology, since it aims to provide wireless broadband services. In the 4th Chapter methodologies for integrating the two types of networks, are presented along with examples of interoperability between GPRS / UMTS and WLANs or between UMTS and WiMAX. Extensive discussion around the problems that should be faced, as the guarantee of bearable QoS level, the mechanisms for handover between the networks and the management of mobility of users and terminals, is held. Moreover, examples of integrated networks with both loose and tight coupling methodologies are presented. The last section of the chapter concerns a detailed description of architectures for interconnecting heterogeneous wireless networks over IP – based backhaul networks, namely All – IP networks, with special focus on policy based handover mechanisms and techniques for managing micromobility and macromobility issues. The 5th Chapter concerns the changes taking place in the telecommunications market deriving from the technological progress in the subject of heterogeneous wireless networks interconnection. New service packets are created, as a result of new business plans that are drawn up by the big telecommunications organizations. Finally, we present the developments in the Greek market and subsidised projects from Information Society AE, via which wireless networks have been materialised, with aim to promote Broadband Services.

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.

With the convergence of the wireless networks and the Internet and the booming demand for multimedia applications, the next-generation (beyond the third generation, or B3G) wireless systems are expected to be all IP-based and provide real-time and non-real-time mobile services anywhere and anytime. Powerful and efficient mobility support is thus the key enabler to fulfil such an attractive vision by supporting various mobility scenarios. This thesis contributes to this interesting while challenging topic. After a literature review on mobility support architectures and protocols, the thesis starts presenting our contributions with a generic multi-layer mobility support framework, which provides a general approach to meet the challenges of handling comprehensive mobility issues. The cross-layer design methodology is introduced to coordinate the protocol layers for optimised system design. Particularly, a flexible and efficient cross-layer signalling scheme is proposed for interlayer interactions. The proposed generic framework is then narrowed down with several fundamental building blocks identified to be focused on as follows. As widely adopted, we assume that the IP-based access networks are organised into administrative domains, which are inter-connected through a global IP-based wired core network. For a mobile user who roams from one domain to another, macro (inter-domain) mobility management should be in place for global location tracking and effective handoff support for both real-time and non-real-lime applications. Mobile IP (MIP) and the Session Initiation Protocol (SIP) are being adopted as the two dominant standard-based macro-mobility architectures, each of which has mobility entities and messages in its own right. The work explores the joint optimisations and interactions of MIP and SIP when utilising the complementary power of both protocols. Two distinctive integrated MIP-SIP architectures are designed and evaluated, compared with their hybrid alternatives and other approaches. The overall analytical and simulation results shown significant performance improvements in terms of cost-efficiency, among other metrics. Subsequently, for the micro (intra-domain) mobility scenario where a mobile user moves across IP subnets within a domain, a micro mobility management architecture is needed to support fast handoffs and constrain signalling messaging loads incurred by intra-domain movements within the domain. The Hierarchical MIPv6 (HMIPv6) and the Fast Handovers for MIPv6 (FMIPv6) protocols are selected to fulfil the design requirements. The work proposes enhancements to these protocols and combines them in an optimised way. resulting in notably improved performances in contrast to a number of alternative approaches.

With recent technological advances in wireless communication networks, the need for an efficient architecture for IP mobility is becoming more apparent. Enabling IP mobility architecture is a significant issue for making use of various portable devices appearing on the Internet. Mobile IP, the current standard for IP based mobility management, is capable of providing wireless Internet access to mobile users. The most important feature of Mobile IP is its ability to support the changing point of attachment of the mobile user by an algorithm known as handover. A handover algorithm is needed to maintain connectivity to the Internet whenever the mobile users move from one subnet to another, while simultaneously providing minimum disruption to ongoing sessions. This thesis gives an overview of Mobile IP, its open issues, some of the subsequent enhancements and extensions related to the handover management problem of the mobile user. Description and evaluation of various handover algorithms for Mobile IP which have been proposed to reduce packet loss and delay during handover constitute the core of the thesis. In this thesis, a comparative performance evaluation of the proposed protocols and the combination of them is also presented through simulations.

In this thesis, performances of some Mobile IP handoff schemes have been compared. The comparison has been based on simulation results. Simulation study has been carried out with a MIP model developed using OMNeT++ and available model frameworks. The literature on Mobile IP and several improvements including handoff management schemes have been surveyed. A MIP model has been constructed and then validated with the help of some scenarios in the literature, especially the one found in [7]. The model has been then used to investigate performances of FMIP. The study also included performance of FMIP under local traffic where mobile hosts communicate with each other in the same domain. Simulations are carried out under several scenarios involving UDP and TCP transfers. Mobile host speed and base station buffer size variables have been changed throughout the simulations. The result show that use of L2 triggers reduces handoff latency as both FMIP Post-Reg and Pre-Reg have better performance than HMIP without L2 triggers. The results also show that FMIP Post-Reg is a good candidate for future MIP infrastructures with its low latency handoff characteristics due to bidirectional tunneling between old and new points of attachment. Moreover, the results suggest that FMIP Post-Reg is also the best handoff scheme under local traffic where mobile hosts communicate among each other in the same foreign network.

Vehicular networks are an emerging technology that offer potential for providing a variety of new services. However, extending vehicular networks to include IP connections is still problematic, due in part to the incompatibility of mobile IP handovers with the increased mobility of vehicles. The handover process, consisting of discovery, registration, and packet forwarding, has a large overhead and disrupts connectivity. With increased handover frequency and smaller access point dwell times in vehicular networks, the handover causes a large degradation in performance. This thesis proposes a predictive handover solution, using a combination of a Kalman filter and an online hidden Markov model, to minimize the effects of prediction errors and to capitalize on advanced handover registration. Extensive simulated experiments were carried out in NS-2 to study the performance of the proposed solution within a variety of traffic and network topology scenarios. Results show a significant improvement to both prediction accuracy and network performance when compared to recent proposed approaches.

Mobility management addresses the issues of how to track and locate a mobile node (MN) efficiently. Service management addresses the issues of how to efficiently deliver services to MNs. This dissertation aims to design and analyze integrated mobility and service management schemes for future all-IP based wireless systems. We propose and analyze per-user regional registration schemes extending from Mobile IP Regional Registration and Hierarchical Mobile IPv6 for integrated mobility and service management with the goal to minimize the network signaling and packet delivery cost in future all-IP based wireless networks. If access routers in future all-IP based wireless networks are restricted to perform network layer functions only, we investigate the design of intelligent routers, called dynamic mobility anchor points (DMAPs), to implement per-user regional management in IP wireless networks. These DMAPs are access routers (ARs) chosen by individual MNs to act as regional routers to reduce the signaling overhead for intra-regional movements. The DMAP domain size is based on a MN's mobility and service characteristics. A MN optimally determines when and where to launch a DMAP to minimize the network cost in serving the user's mobility and service management operations. We show that there exists an optimal DMAP domain size for each individual MN. We also demonstrate that the DMAP design can easily support failure recovery because of the flexibility of allowing a MN to choose any AR to be the DMAP for mobility and service management. If access routers are powerful and flexible in future all-IP based networks to perform network-layer and application-layer functions, we propose the use of per-user proxies that can run on access routers. The user proxies can carry service context information such as cached data items and Web processing objects, and perform context-aware functions such as content adaptation for services engaged by the MN to help application executions. We investigate a proxy-based integrated mobility and service management architecture (IMSA) under which a client-side proxy is created on a per-user basis to serve as a gateway between a MN and all services engaged by the MN. Leveraging Mobile IP with route optimization, the proxy runs on an access router and cooperates with the home agent and foreign agent of the MN to maintain the location information of the MN to facilitate data delivery by services engaged by the MN. Further, the proxy optimally determines when to move with the MN so as to minimize the network cost associated with the user's mobility and service management operations. Finally we investigate a proxy-based integrated cache consistency and mobility management scheme called PICMM to support client-server query-based mobile applications, to improve query performance, the MN stores frequently used data in its cache. The MN's proxy receives invalidation reports or updated data objects from application servers, i.e., corresponding nodes (Cans) for cached data objects stored in the MN. If the MN is connected, the proxy will forward invalidation reports or fresh data objects to the MN. If the MN is disconnected, the proxy will store the invalidation reports or fresh data objects, and, once the MN is reconnected, the proxy will forward the latest cache invalidation report or data objects to the MN. We show that there is an optimal ``service area'' under which the overall cost due to query processing, cache consistency management and mobility management is minimized. To further reduce network traffic, we develop a threshold-based hybrid cache consistency management policy such that whenever a data object is updated at the server, the server sends an invalidation report to the MN through the proxy to invalidate the cached data object only if the size of the data object exceeds the given threshold. Otherwise, the server sends a fresh copy of the data object through the proxy to the MN. We identify the best ``threshold'' value that would minimize the overall network cost. We develop mathematical models to analyze performance characteristics of DMAP, IMSA and PICMM developed in the dissertation research and demonstrate that they outperform existing schemes that do not consider integrated mobility and service management or that use static regional routers to serve all MNs in the system. The analytical results obtained are validated through extensive simulation. We conclude that integrated mobility and service management can greatly reduce the overall network cost for mobile multimedia and database applications, especially when the application's data service rate is high compared with the MN's mobility rate. / Ph. D.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper presents work being done at NASA/GSFC by the Operating Missions as Nodes on the Internet (OMNI) project to demonstrate the application of Internet communication technologies to space communication. The goal is to provide global addressability and standard network protocols and applications for future space missions. It describes the communication architecture and operations concepts that will be deployed and tested on a Space Shuttle flight in July 2002. This is a NASA Hitchhiker mission called Communication and Navigation Demonstration On Shuttle (CANDOS). The mission will be using a small programmable transceiver mounted in the Shuttle bay that can communicate through NASA’s ground tracking stations as well as NASA’s space relay satellite system. The transceiver includes a processor running the Linux operating system and a standard synchronous serial interface that supports the High-level Data Link Control (HDLC) framing protocol. One of the main goals will be to test the operation of the Mobile IP protocol (RFC 2002) for automatic routing of data as the Shuttle passes from one contact to another. Other protocols to be utilized onboard CANDOS include secure login (SSH), UDP-based reliable file transfer (MDP), and blind commanding using UDP. The paper describes how each of these standard protocols available in the Linux operating system can be used to support communication with a space vehicle. It will discuss how each protocol is suited to support the range of special communication needs of space missions.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / Ongoing work at National Aeronautics and Space Administration Goddard Space Flight Center (NASA/GSFC), seeks to apply standard Internet applications and protocols to meet the technology challenge of future satellite missions. Internet protocols and technologies are under study as a future means to provide seamless dynamic communication among heterogeneous instruments, spacecraft, ground stations, constellations of spacecraft, and science investigators. The primary objective is to design and demonstrate in the laboratory the automated end-to-end transport of files in a simulated dynamic space environment using off-the-shelf, low-cost, commodity-level standard applications and protocols. The demonstrated functions and capabilities will become increasingly significant in the years to come as both earth and space science missions fly more sensors and the present labor-intensive, mission-specific techniques for processing and routing data become prohibitively. This paper describes how an IP-based communication architecture can support all existing operations concepts and how it will enable some new and complex communication and science concepts. The authors identify specific end-to-end data flows from the instruments to the control centers and scientists, and then describe how each data flow can be supported using standard Internet protocols and applications. The scenarios include normal data downlink and command uplink as well as recovery scenarios for both onboard and ground failures. The scenarios are based on an Earth orbiting spacecraft with downlink data rates from 300 Kbps to 4 Mbps. Included examples are based on designs currently being investigated for potential use by the Global Precipitation Measurement (GPM) mission.

Mobile computing is becoming increasingly important, due to the rise in the number of portable computers and the desire to have continuous network connectivity to the Internet, irrespective of the physical location of the node. We have also seen a steady growth of the market for wireless communication devices. Such devices can only have the effect of increasing the options for making connections to the global Internet. The Internet infrastructure is built on top of a collection of protocols called the TCP/IP protocol suite. Transmission Control Protocol (TCP) and Internet Protocol (IP) are the core protocols in this suite. There are currently two standards: one to support the current IPv4 and one for the upcoming IPv6 [1]. IP requires the location of any node connected to the Internet to be uniquely identified by an assigned IP address. This raises one of the most important issues in mobility because, when a node moves to another physical location, it has to change its IP address. However, the higher-level protocols require the IP address of a node to be fixed for identifying connections. The Mobile Internet Protocol (Mobile IP) is an extension to the Internet Protocol proposed by the Internet Engineering Task Force (IETF) that addresses this issue. It enables mobile devices to stay connected to the Internet regardless of their locations, without changing their IP addresses and, therefore, an ongoing IP session will not be interrupted [2, 3, 4]. More precisely, Mobile IP is a standard protocol that builds on the Internet Protocol by making mobility transparent to applications and higher-level protocols like TCP. However, before Mobile IP can be broadly deployed, there are still several technical barriers, such as long handover periods and packet loss that have to be overcome, in addition to other technical obstacles, including handover performance, security issues and routing efficiency [7]. This study presents an investigation into developing new handover mechanisms based on link layer information in Mobile IP and fast handover in Mobile IPv6 environments. The main goal of the developed mechanisms is to improve the overall IP mobility performance by reducing packet loss, minimizing signalling overheads and reducing the handover processing time. These models include the development of a cross-layer handover scheme using link layer information and Mobile Node (MN) location information to improve the performance of the communication system by reducing transmission delay, packet loss and registration signalling overheads. Finally, the new schemes are developed, tested and validated through a set of experiments to demonstrate the relative merits and capabilities of these schemes.