Made available in DSpace on 2014-06-12T16:00:36Z (GMT). No. of bitstreams: 2 arquivo6790_1.pdf: 1724338 bytes, checksum: 1acef95f16a08ed5cc23c8696c799e0e (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Atualmente, os terminais móveis possuem diferentes interfaces de redes, o que possibilita ao usuário estar conectado à Internet por diferentes tecnologias de acesso sem fio. Esta característica é a base para as redes de quarta geração (4G). Nesse ambiente heterogêneo sem fio, o usuário com um terminal móvel poderá fazer a transição entre estas diferentes tecnologias de acesso, também denominado handover vertical, de forma a estar conectado sempre da melhor forma possível, e a todo momento. Porém, existe a necessidade de que esta seleção de rede seja personalizada pelas preferências de cada usuário, uma vez que nestes novos ambientes 4G, a personalização de serviços é um fator imprescindível. Esta característica torna o processo de handover vertical um dos grandes desafios das redes de próxima geração. Assim, o principal problema é selecionar redes candidatas centradas nas preferências do usuário, porém, sem desconsiderar os requisitos da aplicação e as características das redes. Para reduzir o problema em questão, esta dissertação apresenta um mecanismo de seleção de rede em ambiente heterogêneo sem fio, que utiliza a preferência do usuário como fator principal no mecanismo de seleção de redes, além dos requisitos da aplicação em uso e dos parâmetros das redes candidatas

The differences between networks of mobile operators can be in their achitecture or the optimization of each network. The architecture is standardized which means there will only be differences in the willingness of mobile operators to invest in newer network elements. Network optimization is more important. The way of optimization isn't strictly given and depends on how the operator deals with it. The most important attribute in optimization is balance. The operators try to achieve balance among three important parameters. Those are capacity, coverage and maintaining QoS. Optimization depends on RRM algorithms. The algorithms include various functions such as admission control, congestion control, handover control, power control, etc. These elements don’t only affect the optimization but also affect each other, because they cooperate with each other. For example, an incorrect admission control of the network leads either to frequent network congestion because of a large number of participants in the network (participants are dissatisfied with the services offered by the operator) or to low utilization of the network because of too few participants in the network (the operator is dissatisfied because he is losing the possible earnings). Neither of these posibilities is good for the mobile operator, therefore it is important that the admission control is well balanced.

Wireless local area networks WLAN and Voice over IP technologies enable local low cost wireless telephony, while cellular networks offer wide-area coverage. The use of dual mode WLAN-cellular terminals should allow cost savings by automatically switching from GSM to WLAN networks whenever it is feasible. However, in order to allow user mobility during a call, a handover procedure for transferring a call between the WLAN interface and the cellular network should be defined. The decision algorithm that triggers such a handover is critical to maintain voice quality and uninterrupted communication. Information or measurements collected from the network may be used to anticipate when the connection will degrade to such a point that a handover is desirable in order to allow a sufficient time span for the handover’s successful execution. It is the delay in detecting when to make a handover and the time to execute it that motivates the need for a prediction. The goal of this thesis is therefore to present a method to predict when a handover should be made based upon network conditions. We selected a number of WLAN and VoIP software tools and adapted them to perform the measurements. These tools allowed us to measure parameters of the WLAN’s physical and link layers. Packet losses and jitter measurements were used as well. We have assumed that there is ubiquitous cellular coverage so that we only have to be concerned with upward handovers (i.e, from the WLAN to the cellular network and not the reverse). Finally we have designed and evaluated a mechanism that triggers the handover based in these measurements. / WLAN, trådlöst lokalt nätverk, och IP-telefoni tillsammans gör det möjligt med billig trådlös telefoni, samtidigt som mobiltelefoninätverk erbjuder stor signal beläggning. Att använda WLAN-mobil med dubbla hårdvaruterminaler skulle ge en kostnadsreducering genom att automatisk byta från GSM till WLAN när det är möjligt. Emellertid för att kunna flytta pågående samtal mellan ett WLAN- och ett mobilt gränssnitt, måste en handovermekansim definieras. En beslutsalgoritm som utlöser sådan handover är av stor vikt för att bibehålla röstkvalitet och oavbruten kommunikation. För att tillåta ett tillräckligt tidsspann för handoverns utförande kan information tagen från nätverket användas för att förutse när kommunikationen ska degraderas till en sådan punkt att en handover är önskvärd. Förseningen i detekteringen när en handover ska ske och tiden för utförandet motiverar behovet av förutsägelse. Det här exjobbet introducerar en metod som förutsäger när handover ska börja baserade på nätverksförhållandena. Vi har valt några WLAN och VoIP-program och anpassat dem för att genomföra mätningarna. Programmen tillät oss att mäta WLANs parameter för fysiska och datalänksskikten. Pecket Loss och jitter-mätningar användes likaså. Vi antog att det fanns GSM tjänst på alla platser så att vi endast behövde göra uppg aende handover(t.ex. från WLAN till mobilt nätverk och inte tvärtom). Vi framkallade och testade en mekanism att starta handovern baserade på nätverksmätningarna. / This is the same Ian Marsh as advisor who authored the disseratation http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10572

No / Increasing number of sophisticated services provided by the current wireless communication systems have caused a significant transition from E-commerce to M-commerce. Enterprises have provided considerable new opportunities to promote their businesses accessible from small mobile devices such as personal digital assistant (PDA) or mobiles phones. These facilities are envisioned as the most convenient way of using M-commerce. Using such services from mobile phones or PDAs equipped with GSM/GPRS involve effective mobility management mechanisms in cellular networks¿a popular architecture for wireless networks. Success of such systems will largely depend on the reliable connection for the roaming users. Consequently, Quality of Service (QoS) provision is one of the most challenging issues in the heterogeneous wireless network-based m-commerce systems. Such m-commerce systems enable users to roam between different wireless networks operators and geographical areas while providing interactive broadband services and seamless connectivity. This paper presents an analytical framework to model scarce channels in any cell for maximizing channel utilization and efficient handling of handover requests. Typical numerical experiments are presented to validate the analytical solution against simulation to study the effect of bursty traffic upon the performance of the cell in any cellular networks.

Mobile terminals allow users to access service while on the move. This unique feature has driven the rapid growth in the mobile network industry, changing it from a new technology into a massive industry in less than two decades. In this thesis, an in-depth study of the handover effects of mobile WiMAX networks is carried out. The mobile WiMAX technology is first presented as literature study and then the technologies of handovers for previous generations are introduced in detail. Further, the hard handover of the mobile WiMAX is simulated by Network Simulator-2 (NS-2). In addition, the "ping-pang" effect of handover was investigated and the call blocking and dropping probabilities are implemented using MATLAB. The goal is to find out which parameters have the significant impact on the handover performance. The results showed that the threshold and hysteresis margin of the handover should be selected by considering the tradeoff between the "ping-pang" effect and the extra interference causing to neighboring cells due to the poor quality link. The handover latency of mobile WiMAX is below 50 ms with the traveling speed of mobile station up to 20 m/s.

Mobile communication systems have continued to evolve by the release of new standards for HSPA and the release of new standards for LTE in release 8 and release 9. The new releases aim at providing higher data rates to accommodate the envisioned services of 3GPP in voice, data, image transmission, video, multimedia service and broadband services. Catering for a wide variety of services to satisfy the demands imposed on mobile networks by the user diversity and demanding applications, the air interface has been identified as the major bottleneck in the mobile networks. Network planning engineers and operators are deploying the new air interfaces in the same cell sites, which gives rise to several internetworking issues among the different air interfaces from radio resources management to service call continuity issues due to user's mobility and changing point of attachment. Deployment of different air interfaces coupled with traffic diversity requests further complicates the managements of the mobile networks. One of The main objectives of this research is to propose and evaluate solutions that address the internetworking of the different radio air interfaces in proposing a call admission control algorithm that can utilize different air interfaces capabilities and to determine which traffic types are better suited to be serviced by an interface. The proposed algorithm will consider the availability of the interface, the load of the network and the user equipment capabilities. Another main objective of this research is to propose and evaluate solutions that address changing the point of attachment of the users due to mobility in the form of handover algorithm. The proposed algorithm will consider the coverage of the node, direction and speed of the user, the network load, the air interface availability and the user equipment capabilities. Another main objective of this research is to design and implement a simulation system which includes all 3GPP standardized technologies. The simulation tool was designed as a discrete event simulation (DBS) system which includes all the standardized air interface technologies and services. The simulation tool was designed using Visual C# to take advantage of the object oriented capabilities of the Windows environment and libraries. The simulation tool was essential in evaluating the proposed algorithms in the first two objectives.

BOMFIM, Michel Sales. Um Mecanismo de melhoria de handovers verticais utilizando endereçamento multicast e serviços do MIH 802.21. 2011. 103 f. Dissertação (Mestrado em ciência da computação)- Universidade Federal do Ceará, Fortaleza-CE, 2011. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-07-11T19:38:38Z No. of bitstreams: 1 2011_dis_msbonfim.pdf: 3117026 bytes, checksum: 19ea0e074c6fbc2bcfe5f4bf287e7889 (MD5) / Approved for entry into archive by Rocilda Sales (rocilda@ufc.br) on 2016-07-20T12:06:35Z (GMT) No. of bitstreams: 1 2011_dis_msbonfim.pdf: 3117026 bytes, checksum: 19ea0e074c6fbc2bcfe5f4bf287e7889 (MD5) / Made available in DSpace on 2016-07-20T12:06:35Z (GMT). No. of bitstreams: 1 2011_dis_msbonfim.pdf: 3117026 bytes, checksum: 19ea0e074c6fbc2bcfe5f4bf287e7889 (MD5) Previous issue date: 2011 / The use of multi-interface devices such as smart phones has grown at the same time as the demands for efficient mobility services in heterogeneous networks. In this scenario, the idea of service continuity has become a crucial requirement. To achieve these demands, efficient handover schemes should be developed aiming to achieve Seamless Handover, which means the change of network domains in a transparent way and without services discontinuity to the end user. Currently, there are different schemes for handover and some of them may be used between different access technologies (Vertical Handover). However, the service time disruption is still a major problem to be solved. The main purpose of this study is to propose an improvement for Vertical Handovers using IP mobility, aiming at Seamless Handover. In this work, the framework provided by the MIH (Media Independent Handover) IEEE 802.21 is used to enable vertical handover in heterogeneous networks, and propose an extension of FMIPv6 (Fast Handovers for Mobile IPv6) called FaHMA (Fast Handovers using Multicast Addressing), using multicast in order to manage mobility in these types of networks. To make the performance analysis, we decided for simulations and we considerered metrics such as the handover delay and packet loss as the most important criteria for evaluating the effectiveness of our proposal. Simulation results have shown that FaHMA achieve better results than FMIPv6, including factors that determine the quality of operation in networked multimedia applications. / O uso de dispositivos multi-interface, tais como smart phones, tem crescido ao mesmo tempo que as demandas por melhores serviços de mobilidade em redes heterogêneas. Neste cenário, a ideia da continuidade de serviços tornou-se um requisito crucial. Para atender essas demandas, esquemas eficientes de handover devem ser desenvolvidos com o objetivo de alcançar o chamado Handover Transparente, que significa a mudança de domínios de rede de uma forma transparente e sem a descontinuidade dos serviços para o usuário final. Atualmente, existem diferentes esquemas de handover e alguns deles podem envolver diferentes tecnologias de acesso (Handover Vertical). Entretanto, o tempo de interrupção do serviço ainda é um problema a ser resolvido. A principal proposta deste trabalho é uma melhoria para Handovers Verticais utilizando mobilidade IP, objetivando o tão desejado Handover Transparente. Neste trabalho, fez-se uso do framework MIH (Media Independent Handover) fornecido pelo padrão IEEE 802.21 para habilitar o handover vertical em redes heterogêneas. Além disso, propõe-se uma extensão do protocolo FMIPv6 (Fast Handovers for Mobile IPv6), o FaHMA (Fast Handovers using Multicast Addressing), utilizando endereçamento multicast para gerenciar a mobilidade nesses tipos de rede. Para fazer a análise de desempenho, simulações foram utilizadas considerando-se métricas tais com o atraso do handover e a perda de pacotes como os critérios mais importantes para avaliar a efetividade da solução. Os resultados destas simulações mostraram que o FaHMA obtêm melhores resultados que o FMIPv6, inclusive em relação aos fatores que determinam a qualidade do funcionamento de aplicações multimídias em rede.

Le monde des communications par satellite est dominé par les systèmes de diffusion de la télévision. Cependant, des satellites de communication offrent aussi des services de téléphonie et de données. Ils sont regroupés dans les familles des systèmes fixes et mobiles et ciblent des marchés de niche. Dans cette thèse, nous avons la volonté d’étendre les scénarios d’utilisation de ces systèmes. Notre vision nous dicte que leur développement est lié à l’utilisation de réseaux hybrides mobiles satellite-terrestre. En effet, une utilisation complémentaire des deux segments permet de s’affranchir d’une concurrence trop féroce des réseaux de télécommunications terrestres. Pour cela, nous optons pour deux applications qui nous paraissent prometteuses : un réseau mobile LTE (Long Term Evolution) avec des stations de base qui possèdent un backhaul satellite et un réseau MANET (Mobile Ad-hoc NETwork) qui s’interconnecte à des réseaux extérieurs grâce à des liaisons satellite. Nous soulevons l’un des problèmes les plus contraignants du réseau mobile LTE avec des backhauls satellite : la gestion de la mobilité. L’analyse du standard nous a conduits à conclure quant à la nécessité d’optimiser les procédures du handover. Ceux qui nécessitent des modifications surviennent entre des stations de base qui n’utilisent pas le même backhaul satellite et entre une station de base avec un backhaul satellite vers une avec un backhaul terrestre. Deux points nous ont semblé importants : la phase de préparation et le mécanisme qui permet d’éviter les pertes. Nous proposons donc une nouvelle phase de préparation qui prend en compte le retard induit par la liaison satellite ainsi qu’une phase de préparation à double décision combinée avec une préparation de multiples stations de base. Nous tentons ainsi de maximiser les chances de réaliser un handover avec succès. Puis, nous avons imaginé un mécanisme qui permet à la fois d’éviter les pertes lors de l’exécution du handover et de sauvegarder les précieuses ressources du satellite. Les réseaux MANET associés à des liaisons satellite offrent des caractéristiques très intéressantes pour les communications d’urgence, telles que l’indépendance vis-à-vis des infrastructures terrestres susceptibles d’être endommagées par des catastrophes ainsi qu’un déploiement rapide pour une intervention sur le théâtre des opérations. Nous avons souhaité améliorer l’un des points cruciaux dans le cadre d’une hybridation : la sélection de la passerelle satellite. Nous avons donc développé un mécanisme qui prend en compte la charge sur les passerelles satellite ainsi que le phénomène d’oscillation de passerelle souvent négligé dans la littérature. Ces optimisations ont pour but de favoriser le développement de réseaux hybrides satellite terrestres en améliorant les performances de ces réseaux. L’avenir nous semble prometteur quant à l’utilisation de la technologie LTE avec un backhaul satellite pour lequel nous avons proposé une nouvelle gestion de la mobilité qui est primordiale pour son développement. / Satellite communications are leaded by television broadcasting. Yet, fixed and mobile satellite systems provide voice services as well as IP-based applications. In this thesis, we try to develop user scenarios in order to extend their targeted market. Our vision to reach this objective consists to use hybrid satellite and terrestrial mobile networks. This network design avoids a competition between both segments in which a satellite success is difficult to imagine. Furthermore, hybrid networks may draw benefits from both segments. Two promising scenarios have been selected. The first one consists in a mobile LTE network (Long Term Evolution) with base stations backhauled by satellite links whereas the second scenario is composed of a Mobile Ad-hoc Network (MANET) connected to external networks thanks to satellite systems. One of the main problems in the hybrid LTE scenario is caused by mobility procedures. As a consequence of the standard analysis, we have decided to optimize the mobility management in two cases: a handover between two base stations for which the backhaul is provided by two different satellite terminals and a handover from a base station with a satellite backhaul to one with a terrestrial backhaul. Two procedures have drawn our attention: the preparation phase and the loss avoidance mechanism during the execution phase. First of all, we design a new procedure for the preparation which takes into account the delay induced by the satellite link. This new phase is based on a twofold decision preparation associated with multiple preparations. This solution leads to an increase of handover success. The second optimization aims to avoid losses during the execution phase and, at the same time, save satellite resources. MANET and satellite hybridization leads to very interesting characteristics for public safety communications. Indeed, these networks are independent of terrestrial infrastructures that can be impaired or destroyed. Furthermore, they can be rapidly deployed in the theater of operation. Gateway selection is a crucial problem linked to hybrid MANET. Therefore, we have focused our work on this mechanism taking into account the measured load on the satellite links as well as an oftenneglected phenomenon, the gateway flapping. These optimizations tend to promote hybrid satellite and terrestrial networks improving their performance. A promising future is foreseen for the hybrid LTE technology and we have proposed a solution to a problem that may be very detrimental to its deployment.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-19T14:37:00Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Proposta de dissertação - Completa - vFinal_entrega.pdf: 3978842 bytes, checksum: bfd74789ed1d6b8fb83c52919ed64fe3 (MD5) / Made available in DSpace on 2017-04-19T14:37:00Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Proposta de dissertação - Completa - vFinal_entrega.pdf: 3978842 bytes, checksum: bfd74789ed1d6b8fb83c52919ed64fe3 (MD5) Previous issue date: 2016-08-30 / As redes corporativas têm evoluído para um ambiente heterogêneo (rede sem fio e cabeada). Estas redes consideram a autenticação do usuário um elemento primordial para garantir níveis adequados de segurança no acesso aos serviços estratégicos da organização. Nas instituições de ensino e pesquisa, o sistema federado baseado na autenticação 802.1x chamado Eduroam (Education Roaming) permite que estudantes e pesquisadores obtenham conectividade sem fio utilizando as mesmas credenciais de suas instituições em qualquer lugar do mundo com suporte a este sistema. Contudo, a qualidade de serviço (QoS) percebida pelo usuário pode ser degradada quando da necessidade de mudança do ponto de acesso sem fio (handover) devido à mobilidade e necessidade de reautenticação de uma sessão em andamento. Apesar das inúmeras soluções existentes na literatura para o gerenciamento de mobilidade, o suporte à autenticação do usuário no processo de handover é um aspecto negligenciado. Esta dissertação propõe um arcabouço para o gerenciamento integrado de redes cabeadas e sem fio baseado em software de código aberto e de baixo custo. A proposta visa tornar o gerenciamento mais simples e centralizado utilizando o paradigma de redes definidas por software (SDN – Software Defined Networking) através do protocolo OpenFlow (OF). Via interface Web é possível obter informações da rede, gerenciar fluxos e controladores OF, criar slices de rede e aplicar políticas de QoS. No contexto do gerenciamento de mobilidade, a proposta implementa e avalia uma estratégia de cache de autenticação que otimiza a qualidade de experiência (QoE) durante o processo de handover e ambiente com autenticação 802.1x/Eduroam. A avaliação foi realizada num ambiente de experimentação e a proposta obteve como resultados os seguintes ganhos: 15,8% na vazão, 25% no atraso médio e 20,5% no PSNR em relação ao cenário de não utilização da proposta de cache de autenticação. Os resultados obtidos demonstram a aplicabilidade da proposta no gerenciamento mobilidade seguro, bem como sua eficácia no suporte aos requisitos de QoS/QoE para sessões de tráfego de vídeo de usuários móveis. / Corporate networks have evolved into a heterogeneous environment (wired and wireless networks). These networks consider user authentication as a key element to ensure adequate levels of security access to the organization's strategic services. In educational and research institutions, the federated system based on 802.1x authentication called Eduroam (Education Roaming) allows students and researchers to gain wireless connectivity using the same credentials of their institutions anywhere in the world that supports this system. However, the quality of service (QoS) perceived by the user can be degraded when they need to change the wireless access point (handover) due to mobility and re-authenticate a session in progress. Despite numerous existing solutions in the literature for mobility management, support for user authentication in the handover process is a neglected aspect. This dissertation proposes a framework for the integrated management of wired and wireless networks based on low cost and open source software. The proposal aims to make simpler and centralized management using the SDN (Software Defined Networking) paradigm via OpenFlow protocol (OF). Through web interface is possible to obtain information from the network, manage flows and OF controllers, create network slices, and apply QoS policies. In the mobility management context, this proposal implements and evaluates a strategy that improves the quality of experience (QoE) environment with 802.1x authentication / Eduroam. In the evaluated experimental environments, the proposed technique achieved gains up to 15.8% on throughput, 25% on average delay and 20.5% on PSNR in comparison to the baseline scenario without authentication cache. Thus, the obtained results demonstrate the applicability of the integrated network management, as well as its effectiveness in supporting of QoS / QoE requirements for video traffic sessions of the mobile users.

Seamless communication is becoming the main aspect for the next generation of the mobile and wireless networks. Roaming among multiple wireless access networks connected together through one IP core makes the mobility support for the internet is very critical and more important research topics nowadays. Mobile IP is one of the most successful solutions for the mobility support in the IP based networks, but it has poor performance in term of handover delay. Many improvements have been done to reduce the handover delay, which result in two new standards: the Hierarchical MIP (HMIP) and the Fast MIP (FMIP), but the delay still does not match the seamless handover requirements. Finally Seamless MIP (S-MIP) has been suggested by many work groups, which combine between an intelligent handover algorithm and a movement tracking scheme. In This thesis, we show the handover delay reduction approaches, specifically the Seamless Mobile IP. The thesis studies the effects of the S-MIP in the handover delay and the network performance as well. A simulation study takes place to compare between the standard MIP and the new suggested S-MIP protocol in term of handover delay, packet loss and bandwidth requirement. The thesis concludes with the analyzing of the simulation results, evaluating the S-MIP performance and finally gives some suggestions for the future work. / 0046704623257