SIP-based mobility management in next generation networks

The ITU-T definition of next generation networks includes the ability to make use of multiple broadband transport technologies and to support generalized mobility. Next generation networks must integrate several IP-based access technologies in a seamless way. In this article, we first describe the requirements of a mobility management scheme for multimedia real-time communication services; then, we report a survey of the mobility management schemes proposed in the recent literature to perform vertical handovers between heterogeneous networks. Based on this analysis, we propose an application-layer solution for mobility management that is based on the SIP protocol and satisfies the most important requirements for a proper implementation of vertical handovers. We also implemented our proposed solution, testing it in the field, and proving its overall feasibility and its interoperability with different terminals and SIP servers

Multi-layer traffic control for wireless networks

Le reti Wireless LAN, così come definite dallo standard IEEE 802.11, garantiscono connettività senza fili nei cosiddetti “hot-spot” (aeroporti, hotel, etc.), nei campus universitari, nelle intranet aziendali e nelle abitazioni. In tali scenari, le WLAN sono denotate come “ad infrastruttura” nel senso che la copertura della rete è basata sulla presenza di un “Access Point” che fornisce alle stazioni mobili l’accesso alla rete cablata. Esiste un ulteriore approccio (chiamato “ad-hoc”) in cui le stazioni mobili appartenenti alla WLAN comunicano tra di loro senza l’ausilio dell’Access Point. Le Wireless LAN tipicamente sono connesse alla rete di trasporto (che essa sia Internet o una Intranet aziendale) usando un’infrastruttura cablata. Le reti wireless Mesh ad infrastruttura (WIMN) rappresentano un’alternativa valida e meno costosa alla classica infrastruttura cablata. A testimonianza di quanto appena affermato vi è la comparsa e la crescita sul mercato di diverse aziende specializzate nella fornitura di infrastrutture di trasporto wireless e il lancio di varie attività di standardizzazione (tra cui spicca il gruppo 802.11s). La facilità di utilizzo, di messa in opera di una rete wireless e i costi veramente ridotti hanno rappresentato fattori critici per lo straordinario successo di tale tecnologia. Di conseguenza possiamo affermare che la tecnologia wireless ha modificato lo stile di vita degli utenti, il modo di lavorare, il modo di passare il tempo libero (video conferenze, scambio foto, condivisione di brani musicali, giochi in rete, messaggistica istantanea ecc.). D’altro canto, lo sforzo per garantire lo sviluppo di reti capaci di supportare servizi dati ubiqui a velocità di trasferimento elevate è strettamente legato a numerose sfide tecniche tra cui: il supporto per l’handover tra differenti tecnologie (WLAN/3G), la certezza di accesso e autenticazione sicure, la fatturazione e l’accounting unificati, la garanzia di QoS ecc. L’attività di ricerca svolta nell’arco del Dottorato si è focalizzata sulla definizione di meccanismi multi-layer per il controllo del traffico in reti wireless. In particolare, nuove soluzioni di controllo del traffico sono state realizzate a differenti livelli della pila protocollare (dallo strato data-link allo strato applicativo) in modo da fornire: funzionalità avanzate (autenticazione sicura, differenziazione di servizio, handover trasparente) e livelli soddisfacenti di Qualità del Servizio. La maggior parte delle soluzioni proposte in questo lavoro di tesi sono state implementate in test-bed reali. Questo lavoro riporta i risultati della mia attività di ricerca ed è organizzato nel seguente modo: ogni capitolo presenta, ad uno specifico strato della pila protocollare, un meccanismo di controllo del traffico con l’obiettivo di risolvere le problematiche presentate precedentemente. I Capitoli 1 e 2 fanno riferimento allo strato di Trasporto ed investigano il problema del mantenimento della fairness per le connessioni TCP. L’unfairness TCP conduce ad una significativa degradazione delle performance implicando livelli non soddisfacenti di QoS. Questi capitoli descrivono l’attività di ricerca in cui ho impiegato il maggior impegno durante gli studi del dottorato. Nel capitolo 1 viene presentato uno studio simulativo delle problematiche di unfairness TCP e vengono introdotti due possibili soluzioni basate su rate-control. Nel Capitolo 2 viene derivato un modello analitico per la fairness TCP e si propone uno strumento per la personalizzazione delle politiche di fairness. Il capitolo 3 si focalizza sullo strato Applicativo e riporta diverse soluzioni di controllo del traffico in grado di garantire autenticazione sicura in scenari di roaming tra provider wireless. Queste soluzioni rappresentano parte integrante del framework UniWireless, un testbed nazionale sviluppato nell’ambito del progetto TWELVE. Il capitolo 4 descrive, nuovamente a strato Applicativo, una soluzione (basata su SIP) per la gestione della mobilità degli utenti in scenari di rete eterogenei ovvero quando diverse tecnologie di accesso radio sono presenti (802.11/WiFi, Bluetooth, 2.5G/3G). Infine il Capitolo 5 fa riferimento allo strato Data-Link presentando uno studio preliminare di un approccio per il routing e il load-balancing in reti Mesh infrastrutturate.Wireless LANs, as they have been defined by the IEEE 802.11 standard, are shared media enabling connectivity in the so-called “hot-spots” (airports, hotel lounges, etc.), university campuses, enterprise intranets, as well as “in-home” for home internet access. With reference to the above scenarios, WLANs are commonly denoted as “infra-structured” in the sense that WLAN coverage is based on “Access Points” which provide the mobile stations with access to the wired network. In addition to this approach, there exists also an “ad-hoc” mode to organize WLANs where mobile stations talk to each other without the need of Access Points. Wireless LANs are typically connected to the wired backbones (Internet or corporate intranets) using a wired infrastructure. Wireless Infrastructure Mesh Networks (WIMN) may represent a viable and cost-effective alternative to this traditional wired approach. This is witnessed by the emergence and growth of many companies specialized in the provisioning of wireless infrastructure solutions, as well as the launch of standardization activities (such as 802.11s). The easiness of deploying and using a wireless network, and the low deployment costs have been critical factors in the extraordinary success of such technology. As a logical consequence, the wireless technology has allowed end users being connected everywhere – every time and it has changed several things in people’s lifestyle, such as the way people work, or how they live their leisure time (videoconferencing, instant photo or music sharing, network gaming, etc.). On the other side, the effort to develop networks capable of supporting ubiquitous data services with very high data rates in strategic locations is linked with many technical challenges including seamless vertical handovers across WLAN and 3G radio technologies, security, 3G-based authentication, unified accounting and billing, consistent QoS and service provisioning, etc. My PhD research activity have been focused on multi-layer traffic control for Wireless LANs. In particular, specific new traffic control solutions have been designed at different layers of the protocol stack (from the link layer to the application layer) in order to guarantee i) advanced features (secure authentication, service differentiation, seamless handover) and ii) satisfactory level of perceived QoS. Most of the proposed solutions have been also implemented in real testbeds. This dissertation presents the results of my research activity and is organized as follows: each Chapter presents, at a specific layer of the protocol stack, a traffic control mechanism in order to address the introduced above issues. Chapter 1 and Charter 2 refer to the Transport Layer, and they investigate the problem of maintaining fairness for TCP connections. TCP unfairness may result in significant degradation of performance leading to users perceiving unsatisfactory Quality of Service. These Chapters describe the research activity in which I spent the most significant effort. Chapter 1 proposes a simulative study of the TCP fairness issues and two different solutions based on Rate Control mechanism. Chapter 2 illustrates an analytical model of the TCP fairness and derives a framework allowing wireless network providers to customize fairness policies. Chapter 3 focuses on the Application Layer and it presents new traffic control solutions able to guarantee secure authentication in wireless inter-provider roaming scenarios. These solutions are an integral part of the UniWireless framework, a nationwide distributed Open Access testbed that has been jointly realized by different research units within the TWELVE national project. Chapter 4 describes again an Application Layer solution, based on Session Initiation Protocol to manage user mobility and provide seamless mobile multimedia services in a heterogeneous scenario where different radio access technologies are used (802.11/WiFi, Bluetooth, 2.5G/3G networks). Finally Chapter 5 refers to the Data Link Layer and presents a preliminary study of a general approach for routing and load balancing in Wireless Infrastructure Mesh Network. The key idea is to dynamically select routes among a set of slowly changing alternative network paths, where paths are created through the reuse of classical 802.1Q multiple spanning tree mechanisms

Performance assessment of VoIP service over different handover mechanisms in UMTS networks

Many researchers have discussed various topics in universal mobile telecommunication system (UMTS) networks: the process of switching from one cell to another for the subscriber and the impact of the quality of the connection during the transition process, quality of services (QoS), the quality of the uplink and downlink carrier line, the various types of code for the voice transmitted through the Internet, especially the research that discussed voice over internet protocol (VoIP) technology as voice travels from cell to cell in mobile networks, depending on the type of delivery. In this paper, a proposed scenario of a UMTS network was implemented to evaluate the multicellular VoIP movement; the proposed UMTS network was simulated using the OPNET 14.5 simulator. The calculation and analysis of the different parameters of the user while moving from one cell to another with different movement speeds considered, the best mean opinion score (MOS) value (3.19) registered for the scenario (soft handover) comparing with another type of handover (3.00)

ANALYSE DU COMPORTEMENT DU HANDOVER VERTICAL SELON UNE VARIETE DE PROTOCOLES DE TRANSPORT

Ce travail s’inscrit dans un projet visant à assurer une continuité de service pour une application de Voix IP (Internet Protocol) lors de la traversée de deux réseaux mobiles différents. Dans cet article nous nous intéressons à évaluer l’utilisation de différents protocoles de transport TCP (Transport Control Protocol) : TCP New-Reno et TCP Vegas, en considérant différents paramètres liés à la QoS (Quality of Service). Cette évaluation s’effectue dans un contexte de mobilité d’un utilisateur entre deux réseaux mobiles hétérogènes (Wifi et Wimax). La plateforme NS2 (Network Simulator) sera utilisée pour effectuer les mesures nécessaires à cette évaluation de protocoles

Heterogeneous Wireless Networks QoE Framework

With the appearance of small cells and the move of mobile networks towards an all-IP 4G network, the convergence of these with Wi-Fi becomes a possibility which at the same time opens the path to achieve what will become 5G connectivity. This thesis describes the evolution of the different mainstream wireless technologies deployed around the world and how they can interact, and provides tools to use this convergence to achieve the foreseen requirements expected in a 5G environment and the ideal user experience. Several topics were identified as needing attention: handover between heterogeneous networks, security of large numbers of small cells connected via a variety of backhaul technologies to the core networks, edge content distribution to improve latency, improvement of the service provided in challenging radio environments and interference between licensed and unlicensed spectrum. Within these topics a contribution was made to improve the current status by analysing the unaddressed issues and coming up with potential improvements that were tested in trials or lab environment. The main contributions from the study have been: 1. A patent in the wireless security domain that reuses the fact that overlapping coverage is and will be available and protects against man in the middle attacks (Section 5.3). 2. A patent in the content distribution domain that manages to reduce the cost to deliver content within a mobile network by looking for the shortest path to the requested content (Section 6.3). 3. Improvements and interoperability test of 802.21 standard which improves the seamlessness of handovers (Section 4.2). 4. 2 infill trials which focus on how to improve the user experience in those challenging conditions (Sections 7.2 and 7.3). 5. An interference study with Wi-Fi 2.4GHz for the newly allocated spectrum for 4G (Section 8.2). This thesis demonstrates some of the improvements required in current wireless networks to evolve towards 5G and achieve the coverage, service, user experience, latency and security requirements expected from the next generation mobile technology

Mecanismos de mobilidade rápida com suporte de QdS

Mestrado em Engenharia Electrónica e TelecomunicaçõesA área das redes de comunicações está, neste momento, a deparar-se com um novo paradigma causado pela tendência de convergência de redes sem fios e celulares. Desta convergência resultará a existência de uma camada de rede integradora, para facilitar o suporte de mecanismos de Qualidade de Serviço e mobilidade. Aqui, o suporte de mobilidade rápida e transparente, sem ser perceptível pelo utilizador, tem sido alvo de muita atenção, apesar de ainda existirem algumas limitações no seu suporte. A mobilidade transparente entre redes celulares, sem fios e fixas, é ambicionada mas ainda não foi alcançada. O trabalho realizado nesta Dissertação consiste na descrição, especificação, implementação e teste de uma nova arquitectura de mobilidade sobre o protocolo IP. Esta arquitectura é baseada no protocolo de mobilidade Mobility Support for IPv6 e em extensões de Fast Handovers for Mobile IPv6, sendo capaz de efectuar handovers iniciados pelo terminal e pela rede. A mobilidade é transparente entre tecnologias de acesso heterogéneas, através da integração de mecanismos de qualidade de serviço, tais como autorização de handovers, controlo de acesso, reserva e atribuição de recursos no novo ponto de ligação e também integrada com subsistemas de autenticação. São também propostos outros mecanismos de mobilidade rápida que fazem uso do protocolo multicast para distribuir os fluxos de tráfego direccionados ao terminal, pelos routers de acesso vizinhos, permitindo que os terminais móveis mudem para qualquer router de acesso na vizinhança sem interrupção dos serviços em curso. Estes mecanismos foram projectados para terminais móveis com grandes requisitos de mobilidade. No âmbito do projecto IST Daidalos foi efectuada a integração de uma rede de próxima geração (4G) de forma a permitir a realização de testes de desempenho e conformidade aos mecanismos propostos. A presente Dissertação efectua uma avaliação de desempenho de uma arquitectura de mobilidade, em cenários intra- e inter-tecnologia, numa rede de testes real. Nesta avaliação foram utilizadas as métricas de atraso, jitter e perdas de pacotes nas fases de preparação e execução do handover. O impacto deste processo em comunicações de dados sobre TCP e UDP é também analisado. A arquitectura e os resultados obtidos no demonstrador real são apresentados e discutidos. ABSTRACT: The field of network communications is, nowadays, facing a new paradigm caused by the forthcoming convergence of cellular and wireless data networks, which seems unavoidable. This convergence will result on an integration layer, to ease the support for Quality of Service and mobility mechanisms. Here, the support for fast and seamless mobility, not perceptible by the user, has been getting much attention, although several limitations still exist in this support. Seamless mobility between cellular, wireless and wired data networks is envisioned, but not yet achieved. The work performed in the scope of this thesis aims to describe, specify, implement and test a novel mobility architecture based on the IP protocol. This architecture is based on the mobility protocol Mobility Support for IPv6 and on extensions of Fast Handovers for Mobile IPv6 RFCs, and is able to provide mobile terminal and network initiated handovers. The mobility is seamless across heterogeneous access technologies, by integrating Quality of Service mechanisms, such as handover authorization, access control, resources reservation and allocation at the new point of attachment, also integrated with an authentication sub-system. Other novel fast mobility mechanisms are also proposed, which make use of the multicast protocol to distribute the traffic flows directed to the terminal during the handover process among the neighbour access routers, allowing the terminal to handover to any access router in the vicinity without disruption of the ongoing services. These latter mechanisms were designed to mobile terminals with high mobility requirements. In the scope of the IST Daidalos framework an integration process of a next generation (4G) network was carried out in order to perform performance and compliance tests to the proposed mechanisms. Furthermore, this thesis also evaluates the performance of a mobility architecture, both in intra and intertechnology scenarios, in a real testbed. In this evaluation were considered metrics such as packet delay, jitter and loss of the handover in its preparation and execution phases. The impact of the handover on ongoing TCP and UDP data communications is also addressed. The architecture and results obtained from the real demonstrator are also presented and discussed

Security-centric analysis and performance investigation of IEEE 802.16 WiMAX

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Recent Advances in Wireless Communications and Networks

This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters

Support infrastructures for multimedia services with guaranteed continuity and QoS

Advances in wireless networking and content delivery systems are enabling new challenging provisioning scenarios where a growing number of users access multimedia services, e.g., audio/video streaming, while moving among different points of attachment to the Internet, possibly with different connectivity technologies, e.g., Wi-Fi, Bluetooth, and cellular 3G. That calls for novel middlewares capable of dynamically personalizing service provisioning to the characteristics of client environments, in particular to discontinuities in wireless resource availability due to handoffs. This dissertation proposes a novel middleware solution, called MUM, that performs effective and context-aware handoff management to transparently avoid service interruptions during both horizontal and vertical handoffs. To achieve the goal, MUM exploits the full visibility of wireless connections available in client localities and their handoff implementations (handoff awareness), of service quality requirements and handoff-related quality degradations (QoS awareness), and of network topology and resources available in current/future localities (location awareness). The design and implementation of the all main MUM components along with extensive on the field trials of the realized middleware architecture confirmed the validity of the proposed full context-aware handoff management approach. In particular, the reported experimental results demonstrate that MUM can effectively maintain service continuity for a wide range of different multimedia services by exploiting handoff prediction mechanisms, adaptive buffering and pre-fetching techniques, and proactive re-addressing/re-binding