Le Wi-Fi est omniprésent dans les villes, que ce soit par le nombre grandissant de point d'accès public, ou la déploiement massif de points d'accès privés, sous la forme de boxes d'opérateurs notamment. Si nous supposons que l'ensemble de ces points d'accès soient utilisables afin de permettre à n'importe quel appareil d'accéder à Internet, alors nous aurions potentiellement une couverture réseau sur l'ensemble de la ville. Ce postulat nous a conduit à nous demander si le Wi-Fi pouvait être utilisé comme réseau à l'échelle urbaine. Ce réseau pourrait plus particulièrement être utilisé dans un contexte de mobilité. Or, le Wi-Fi n'a pas été conçu dans le but de gérer des utilisateurs mobiles,et les appareils doivent régulièrement changer de points d'accès lorsqu'ils n'ont plus de connectivité. Ce mécanisme, appelé handover, peut être long car les appareils doivent d'abord constater leurs pertes de connectivité avant de commencer à chercher le prochain point d'accès auquel s'associer. Il peut être particulièrement long pour des appareils comme les smartphones car ces derniers sont contraint en énergie et n'appliquent donc pas une politique de handover aggressive. Dans ce contexte nous avons cherché à caractériser les applications possible sur le Wi-Fi lorsqu'un utilisateur est mobile, en fonction de la durée de handover de son équipement, de sa vitesse et de la densité des points d'accès présents dans la ville. Nous avons constaté que pour les utilisateurs se déplaçant à faible allure, l'impact de la durée de handover est faible au regard de la connectivité totale, ce qui leur permet d'utiliser des applications gourmandes en terme de bande passante tant que celles-ci possèdent un certain degré de tolérances aux déconnexions. Cependant lorsque la vitesse de déplacement augmente, la durée de handover dégrade progressivement la connectivité des utilisateurs, de telle sorte que ceux ayant une allure élevée ne peuvent plus espérer utiliser les différents points d'accès. En effet, les équipements passent alors plus de temps à effectuer des handovers qu'à échanger des données applicatives. Les retransmissions jouant un rôle important dans la durée de handover, nous avons étudié finement leurs fonctionnement en 802.11.Pour cela nous avons mis en place un banc d'essai nous permettant d'observer les séquences de messages retransmis par différentes implémentations de 802.11lorsque l'on fait subitement disparaitre le point d'accès. Nous avons comparé ces séquences avec celle décrite dans le standard, et nous avons constaté que le nombre de retransmissions maximal ainsi que l'augmentation de la fenêtre de contention n'étaient pas respectés. De plus, ces implémentations passent beaucoup de temps à tenter de retransmettre avant d'initier leurs procédures de handover. Les retransmissions sont aussi utilisées dans les algorithmes d'adaptation de débits afin de déterminer si le lien se dégrade. Or, lors de la contention, le nombres de pertes augmente avec la plus forte probabilité de collisions. Afin d'observer l'impact des retransmissions sur les algorithmes d'adaptation de débits lors de la contention, nous avons mis en place un banc d'essai composé d'une trentaine de stations identiques. Nous avons constaté que l'algorithme de contrôle de débit utilisé est sous optimal par rapport à l'utilisation d'une modulation unique. Enfin, nous nous sommes intéressés à l'utilisation d'un tel réseau à l'échelle de la ville afin d'acheminer des données ayant une forte validité spatiale. Nous avons alors proposé un schéma d'adressage géographique exploitant l'infrastructure d'Internet. Il permet à la fois d'obtenir un découpage hiérarchique du monde, et d'avoir un préfixe hiérarchique des adresses, similaire à celui de CIDR. Nous montrons que ce schéma d’adressage peut être utilisé dans des adresses multicast pour envoyer des messages à destination de zones géographiques précises (surface minimale d'un mètre carré). / Wi-Fi is everywhere in cities, whether through the growing number of publicaccess points, or the massive private access points deployment, in the formof set-top boxes for the major part.If we assume that all these access points are usable in order to allow anydevice to access the Internet, then we would potentially have network coveragethroughout the city.This assumption led us to wonder if Wi-Fi could be used as a city-wide network.This network could, more specifically, be used in a context of mobility.However, Wi-Fi was not designed to manage mobile users, and devices have tooften change their access points when they no longer have connectivity.This mechanism, called handover, can be long because devices must first detecttheir connectivity losses before they can start looking for the next accesspoint to associate with.It can be particularly long for devices such as smartphones because they areenergy constrained and therefore do not apply an aggressive handover policy.In this context we tried to characterize the possible Wi-FI applications for amoving user, considering the handover duration, the user speed and the accesspoints density in the city.We found that for slow-moving users, the impact of the handover is smallcompared to the their overall connectivity.This allows them to use bandwidth-intensive applications as long as they areto some extend delay-tolerant.However, when the user’s speed increases, the impact of handover’s durationgradually degrades the user’s connectivity, so that high speed users can nolonger expect to use different access points.Fast moving devices spend more time performing handovers with new access pointsthan transmitting application data.Retransmissions play an important role in the duration of handover.In order to study in detail the retransmissions in 802.11, we have set up atestbed allowing us to observe the sequences of retransmitted messages usingdifferent implementations of 802.11 when we suddenly make the access pointdisappear.We compared these sequences with the one described in the standard, and we wefound that the maximum number of retransmissions as well as the growth in thecontention window were not respected.In addition, these implementations spend a lot of time trying to retransmitbefore initiating their handover procedures.Retransmissions are also used in the rate control algorithms to determine ifthe link is deteriorating.However, during contention, the number of losses increases with the higherprobability of collisions.In order to observe the impact of retransmissions on the rate controlalgorithms during contention, we have set up a testbed composed of about thirtyidentical stations.We found that the rate control algorithm used underperforms compared to theuse of a single modulation.Finally, we proposed a geographical addressing scheme compliant with theInternet infrastructure.It allows to obtain both a hierarchical division of the world, and ahierarchical prefix for the addresses, similar to the one used in the CIDRformat.We show that this addressing scheme can be used in multicast addresses to sendmessages to specific geographical areas (minimum area of one square meter).

Résumé Dans les futurs réseaux mobiles, différentes technologies d'accès radio, telles que GSM, UMTS, WiMAX, WIFI coexisteront. Pour réaliser un handover vertical sans couture (handover inter-RAT) entre ces technologies, des architectures d'interconnexion et des moyens pour gérer le handover inter-RAT sont proposés. Afin de proposer une solution efficace, nous allons d'abord analyser la solution " Fast MIPv6 (FMIPv6) ". Les analyses numériques démontrent les défauts de FMIPv6 et les exigences de handover inter-RAT. En considérant une architecture de couplage intégré (integrated coupling), nous proposons une nouvelle sous-couche commune d'interconnexion (IW sublayer) au niveau 2 sur le RNC (Radio Network Controller) et le MS (Mobile Station) pour offrir un handover inter-RAT sans couture entre les systèmes UMTS et WiMAX. Cette sous-couche IW permet d'éliminer la perte des paquets et de réduire la latence de handover. Ces paramètres sont des éléments importants communs à la plupart des scénarios de handover inter-RAT. Cette sous-couche IW est également étendue à l'architecture de couplage serré (tight coupling). En outre, deux types de solution basées sur TCP Proxy, qui utilisent la sous-couche IW, sont également introduites sur le RNC pour résoudre deux problèmes rencontrés avec l'utilisation du trafic TCP dans un handover inter-RAT: le " BDP mismatch " et le " spurious RTO (Retransmission TimeOut) ". Le premier type de solution basé sur TCP Proxy est adapté aux scénarios où le handover est fréquent, tandis que le deuxième type de solution basé sur TCP Proxy est conçu pour les scénarios où le handover est occasionnel. Par rapport aux autres solutions de handover vertical, les résultats de simulation montrent que notre deuxième type de solution a le mérite de maintenir la pile de protocole TCP existante inchangée. Les solutions classiques de handover inter-RAT sont généralement réalisées au niveau 2 ou au-dessus, parce qu'il n'y a pas de module commun à la couche physique pour les deux systèmes, ou en raison de la distance géographique des systèmes. Mais pour les futurs systèmes LTE et WiMAX dans à l'architecture " integrated coupling ", ce n'est pas le cas, parce qu'ils ont un certain nombre de techniques physiques communes, telles que MIMO et OFDM. Deux modules nommés " precoder " et " combiner " sont proposés respectivement sur les BSs (stations de base) et sur le MS au niveau physique afin d'exploiter au maximum la diversité des deux réseaux d'accès radio et de réaliser un " soft " handover inter-RAT. Ce " soft " handover inter-RAT au niveau physique est entièrement nouveau à notre connaissance.

Handling mobility in wireless sensor networks can pose formidable challenges in protocol design, especially, at the link layer. Since most of the proposed Medium Access Control (MAC) protocols do not accommodate mobility, a node has two options to deal with a deteriorating link: (a) to continue data transmission until the link breaks and then establishes a new link with a new relay node; or (b) to seamlessly transfer the communication to a better link parallel to the data transmission over the existing link. Different from option (a) where a node can only search for a new link after the original link disrupts, option (b) enables a node to perceive the change in the quality of a link in advance. The link quality prediction is implemented by an adaptive handover mechanism. Both approaches will inevitably introduce latency. This thesis aims to quantify and compare such latency. Specifically, it investigates the latency of packet transmission in a mobile wireless sensor network with and without the support of a handover mechanism. To start with, the thesis elaborates the effect of mobility on the performance of the existing MAC protocols, and the need to maintain an unbroken link during data transmission. To implement the handover, a target MAC protocol is required to be selected first. Since the Receiver-Initiated MAC protocol (RI-MAC) uses only short beacon and data packets during communication that substantially reduce overhearing, collision probability and data recovery cost, it is chosen as the carrier for the latency evaluation. Even though RI-MAC performs well in many aspects, it has several demerits. To address the monotonous increment in the backoff window size and to reduce the occurrence frequency of the dwell time, a burst data transmission pattern is adopted to optimize RI-MAC. With the optimization, the protocol reduces the long idle listening time that a node has to wait before data transmission, and thus, works well in a static scenario. However, due to the high probability of link disconnection, the burst data transmission does not perform well in case of mobility. For the sake of accommodating mobility, an adaptive handover mechanism is developed on top of the optimized RI-MAC. Once a node evaluates that the data packets cannot be completely transmitted before the link terminates, it will search for a new relay node while keeping communicating with the original collaborator. It is implemented by embedding a neighbor discovery request in a data packet that will be transmitted in a broadcast channel. Neighbors of the node will participate in the handover process as long as they are in an active state and their distance to the transmitter does not exceed a pre-defined threshold. As a proof-of-concept for the handover mechanism, a mathematical model is established. The transmission rate, the moving speed of human beings, the duty cycle and the network density are all taken into consideration. The analytical result shows that the communication latency decreases with an increment in the network density and the duty cycle when the handover mechanism is used, whereas the latency exhibits a reverse trend when the handover mechanism is not used. To validate the mathematics-based evaluation, the NS2 network simulator is employed. The simulation result is found to perform in accordance with the analytical result. It is asserted that the latency of packet transmission with the handover support is much less than that without the handover support. The communication latency can be saved by at least 0.28s when the handover mechanism is applied. This figure can even grow as the duty cycle and the network density increase. From this perspective, the handover mechanism is verified to improve the latency of packet transmission as far as mobility is concerned.

The inherent broadcast nature of satellites, their global coverage and direct access to a large number of subscribers give satellites unrivalled advantages in supporting IP multicast applications. A new generation of satellite systems that support regenerative on-board processors and multiple spot beam technology have opened new possibilities of implementing IP multicast communication over satellites. These new features enable satellites to make efficient use of their allocated bandwidth resources and provide cost effective network services but equally, create new challenges for mobile satellite terminals. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on continental flights, maritime vessels, etc., still remain big challenges that have received very little attention from the research community. Up till now, there are no proposed mechanisms to support IP multicast for mobile receivers/sources in multi-beam satellite networks in open literature. This study explores the suitability of IP multicast mobility support schemes defined for terrestrial networks in a satellite environment and proposes novel schemes based on the concepts of Home and Remote subscription-based approaches, multiple interface and PMIPv6 protocol. Detailed analysis and comparison of results obtained from the proposed schemes, Mobile IP (MIP) Home and Remote subscription-based approaches (for terrestrial networks) when implemented on a reference multi-beam satellite network are presented. From these results, the proposed schemes outperform the MIP Home and Remote subscription-based approaches in terms of gateway handover latency, number of multicast packets lost and signalling cost over the satellite air interface.

[pt] A existência de várias tecnologias para acesso a Internet é uma realidade dos nossos dias. Um subconjunto muito importante destas tecnologias, que segue em pleno desenvolvimento, é o das redes sem fio. Diante das alternativas tecnológicas e da demanda crescente por aplicações multimídia, de preferência com conexões do tipo AAA (Anyone Anywhere Anytime), a interoperação entre diferentes redes de acesso sem fio se torna bastante interessante. Seguindo esta tendência, o IEEE (Institute of Electrical and Eletronics Engineers) realizou a especificação de um protocolo que auxilia o processo de handover entre redes de diferentes tecnologias (handover vertical) chamado IEEE 802.21 conhecido também por MIH (Media Independent Handover). Esta dissertação apresenta um estudo sobre aspectos de gerência de mobilidade e do processo de handover vertical entre as tecnologias UMTS (Universal Mobile Telecommunication System), WiMax (IEEE 802.16) e WiFi (802.11) através do protocolo IEEE 802.21. Nela, é confeccionada uma proposta teórica de um algoritmo de decisão de handover vertical entre redes sem fio locais e geograficamente distribuídas para uma topologia comumente encontrada atualmente. São realizadas, através do software ns2 (Network Simulator), simulações do handover vertical envolvendo as tecnologias referidas com o suporte do protocolo IEEE 802.21. Ao final, são feitas as análises e conclusões dos resultados obtidos. / [en] A variety of technologies to access the Internet is a reality today. An important subset of these technologies, which follows in full development, is the wireless networks. Given the technological alternatives and increasing demand for multimedia applications, preferably with connections AAA (Anyone Anywhere Anytime), interoperation between different wireless access networks is quite interesting. Following this trend, the IEEE (Institute of Electrical and Electronics Engineers) held a protocol specification that helps the process of handover between networks of different technologies (vertical handover) called IEEE 802.21 also known as MIH (Media Independent Handover). This work presents a study on aspects of mobility management and vertical handover process between UMTS (Universal Mobile Telecommunication System), WiMax (IEEE 802.16) and WiFi (802.11) technologies using IEEE 802.21 protocol. In it, there is a theoretical proposal of a decision algorithm for vertical handover between local and geographically distributed wireless networks to a topology commonly found today. Simulations involving vertical handover in these technologies, with the support of the IEEE 802.21 protocol, are performed using the software ns2 (Network Simulator). At the end, analyzes and conclusions of results are made.

Made available in DSpace on 2014-12-17T14:55:38Z (GMT). No. of bitstreams: 1 DiegoFS.pdf: 4121922 bytes, checksum: 12733aecf16cb4251d84ab4d4f8172a2 (MD5) Previous issue date: 2009-09-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This dissertation has the purpose to present a portable device named PlugData MG100G, equipped with a cellular module, to analyze the radiofrequency coverage in a GSM network situated in Jo?o Pessoa city, state of Para?ba, at four distinct regions. The equipment, originally, was developed to be used in fixed environments, so it was adapted so that it could be used in conditions of mobility. From the Mobile Measurement Reports (MMRs) RF coverage and the handover process are analyzed. The MMRs enable the identification of the serving cell and the list of the closest neighboring cells monitored by the mobile. This work analyses only data referent to the serving cell and the two closest neighboring cells. Inter-cell and intra-cell handovers are identified. The frequency planning and quality of service offered by the network related to the regions are discussed as well / Esta disserta??o apresenta a aplica??o de um aparelho port?til, PlugData MG100G, equipado com um m?dulo celular, para an?lise de cobertura de radiofreq??ncia em uma rede GSM na cidade de Jo?o Pessoa - PB em quatro regi?es distintas. O equipamento, originalmente, foi criado para uso em ambientes fixos, e para isso, tornou-se necess?ria sua adapta??o para que fosse utilizado em condi??es de mobilidade. A an?lise de RF ? feita atrav?s do Mobile Measurement Reports (MMRs) que s?o usados com prop?sitos de avaliar o handover na rede. Por interm?dio do Measurement Reports ? poss?vel identificar a c?lula que serve o m?vel e uma lista de c?lulas vizinhas mais pr?ximas monitoradas pelo pr?prio m?vel. Neste trabalho s?o analisados apenas os dados referentes ? c?lula servidora e ?s duas c?lulas vizinhas mais pr?ximas. Verificam-se tanto handovers inter c?lulas (entre c?lulas) como handovers intra c?lulas (no interior das c?lulas). Atrav?s dos resultados obtidos pode-se fazer uma an?lise em rela??o ao planejamento de freq??ncias criado para as regi?es onde as medidas foram realizadas e ? qualidade de servi?o oferecida pela rede

Atualmente tem crescido o uso de aparelhos móveis com mais de uma interface de rede para o acesso à Internet, caracterizando em parte as Redes de Próxima Geração (NGN). Outras características da NGN são o acesso sob demanda, no qual o cliente de acesso não seria, necessariamente, usuário de um único provedor e usaria a rede de outros provedores conforme a necessidade, e o gerenciamento de handover (trocas de rede) centrado no usuário, no qual o usuário é quem decide à qual rede vai se conectar e em que momento. Existem algumas implicações relacionadas ao acesso sob demanda que podem melhorar ou piorar a experiência de acesso do usuário e causar certos impactos relacionados à vazão recebida, valor gasto, número de handovers, entre outros. Para o dispositivo móvel gerenciar os handovers, ele precisa obter informações sobre as redes disponíveis como, por exemplo, preço e incentivos, além das informações já obtidas atualmente como força do sinal recebido e identificador do provedor (SSID). Porém, os provedores não possuem um sistema automatizado para fornecer tais informações aos dispositivos móveis. Esta tese apresenta uma avaliação dos impactos das trocas dinâmicas entre provedores Wi-Fi para o usuário móvel, comparando o acesso sob demanda com o acesso tradicional (como é feito atualmente). Como metodologia para esta avaliação, foram realizadas simulações de redes em um cenário com provedores Wi-Fi com perfis diferentes, nas quais foram analisados o número de handovers realizados, a quantidade de bytes recebidos e o valor gasto com o acesso. Nestas simulações o usuário pôde priorizar o custo da conexão, a força do sinal recebido e a carga de trabalho no ponto de acesso para decidir a troca de rede. Esta tese também apresenta uma arquitetura para provimento de informações adicionais sobre as redes disponíveis em um ambiente de acesso sob demanda com gerenciamento de handover centrado no usuário, chamada MYHand (MIH-based and Y-Comm-based Handover Management). Para isso foi utilizada a arquitetura para acesso sob demanda chamada Y-Comm e o padrão IEEE 802.21 (MIH Media Independent Handover). Os resultados desta tese contribuem no gerenciamento das trocas de rede e ubiquidade do acesso à Internet em NGN. A arquitetura MYHand auxiliará o dispositivo móvel a obter mais informações necessárias à decisão de handover, podendo otimizá-la. Com os resultados das simulações, o dispositivo móvel poderá prever o quanto determinada decisão poderá beneficiar a experiência do usuário em termos de qualidade da conexão e custo / Currently, the usage of mobile devices with multiple network interfaces for Internet access has been growing, characterizing partially the Next Generation Networks (NGN). Other features of the NGN are access on demand, in which the customer is not, necessarily, user of a single provider and would use the network of other providers as needed, and the user-centric handover management, in which the user decides which network to connect to and at which time. There are some implications related to access on demand which can improve or worsen the user access experience and cause some impacts related to throughput, paid value, number of handovers, among others. The mobile can manage the handovers but he needs to obtain information about available networks as, for example, price and incentives, in addition to the information already obtained currently as received signal strength and provider identifier (SSID). However, providers do not have an automated system to provide such information to mobile devices. This thesis presents an evaluation of the impacts of dynamic switching between Wi-Fi providers for the mobile user, comparing access on demand to the traditional approach (as currently done). As methodology for this evaluation, simulations were performed in a scenario with Wi-Fi providers with different profiles, in which the number of handovers performed, the amount of received bytes, and the paid value were analyzed. In these simulations the mobile user could prioritize the cost of the connection, the received signal strength, and the load on the access point to decide the handover. This thesis also presents an architecture for additional information provisioning about available networks in an access on demand environment with user-centric handover management, called MYHand (MIH-based and Y-Comm-based Handover Management). For this purpose, an architecture for access on demand called Y-Comm and the IEEE 802.21 standard (MIH Media Independent Handover) were used. The results of this thesis contribute to the handover management and ubiquity of Internet access in NGN. The MYHand architecture will assist the mobile device to obtain more information, necessary to the handover decision, optimizing it. With the results of the simulations, the mobile device can predict how much a particular decision may benefit the user experience in terms of connection quality and cost

Bakgrund: Akutsjukvård bedrivs under dygnets alla timmar, oberoende av verksamhet och plats och innefattar både ambulanssjukvård och akutmottagningar där legitimerade sjuksköterskor eller kvalificerad personal arbetar. Överlämningen innebär en process som involverar överförande av information samt en övergång av vård till nästa vårdgivare. Utifrån kvaliteten på överlämningen och den rapport som ges från ambulanspersonal till sjuksköterska på akutmottagning skapas förutsättningar för patientens fortsatta vård. Överrapporteringen kan ske på flera olika sätt och flera aspekter kan påverka denna process som involverar både ambulanspersonal, sjuksköterskor på akutmottagning och patienten. Syfte: Syftet var att belysa sjukvårdspersonalens upplevelser av överrapportering då patienter anländer med ambulans till akutmottagning. Metod: En kvalitativ litteraturstudie med induktiv design. Artiklar har sökts i databaserna PubMed och Cinahl. Dataanalysen utfördes utifrån Bettany-Saltikov och McSherrys beskrivning av kvalitativ innehållsanalys. Resultat: I resultatet framkom fyra huvudkategorier: Det gemensamma omhändertagandet, Arbetet mot samma mål, Vikten av en god relation samt Omgivningens betydelse. Slutsats: Överrapporteringen behöver struktureras för att sjukvårdspersonalen ska arbeta på ett mer enhetligt sätt. En ökad förståelse för varandras arbetssituation och ett bättre samarbete mellan sjukvårdspersonal kan leda till en ökad patientsäkerhet. Genom en förbättrad kommunikation och en involverad patient i överrapporteringen kan kvaliteten förbättras och förlust av viktig data minska. / Background: Emergency care is provided around the clock, regardless of activity and location, and includes both ambulance care and emergency department where registered nurses or qualified staff work. The handover is a process that involves the transfer of information and transfer of care to the next care provider. Based on the quality of the handover and the report given from ambulance staff to the nurse in the emergency department, conditions are created for the patient’s continued care. There are several aspects that can affect the handover in the process that involves both ambulance staff, nurses in the emergency department and the patient. Aim: The aim of the study was to illustrate healthcare staff’s experiences of handover when patients arrive by ambulance to the emergency department. Method: Systematic literature study with qualitative method. The articles were searched in the databases PubMed and Cinahl. Data were analyzed based on Bettany-Saltikov and McSherry’s description of qualitative content analysis. Results: The result included four main categories: The common care, Working towards the same goal, The importance of a good relationship and The importance of the environment. Conclusion: The handover needs to be structured so that the healthcare staff can work in a more homogenous way. An increased understanding of each other's work situation and a better collaboration between the healthcare staff can lead to increased patient safety. Through improved communication and the patient involved in the handover the quality can be improved and the loss of important data can be reduced.

The inherent broadcast nature of satellites, their global coverage and direct access to a large number of subscribers give satellites unrivalled advantages in supporting IP multicast applications. A new generation of satellite systems that support regenerative on-board processors and multiple spot beam technology have opened new possibilities of implementing IP multicast communication over satellites. These new features enable satellites to make efficient use of their allocated bandwidth resources and provide cost effective network services but equally, create new challenges for mobile satellite terminals. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on continental flights, maritime vessels, etc., still remain big challenges that have received very little attention from the research community. Up till now, there are no proposed mechanisms to support IP multicast for mobile receivers/sources in multi-beam satellite networks in open literature. This study explores the suitability of IP multicast mobility support schemes defined for terrestrial networks in a satellite environment and proposes novel schemes based on the concepts of Home and Remote subscription-based approaches, multiple interface and PMIPv6 protocol. Detailed analysis and comparison of results obtained from the proposed schemes, Mobile IP (MIP) Home and Remote subscription-based approaches (for terrestrial networks) when implemented on a reference multi-beam satellite network are presented. From these results, the proposed schemes outperform the MIP Home and Remote subscription-based approaches in terms of gateway handover latency, number of multicast packets lost and signalling cost over the satellite air interface.

Recent studies have shown that there are currently more than 1.08 billion of Smartphones in the world, with around 89% of them used throughout the day. On average each of these users transfers more than 450 Mbytes per month via either a cellular network or a Wi-Fi network. So far it has been up to the user to decide which one of these two networks to use at each particular moment. In this master’s thesis, the potential energy savings that could be achieved by means of automating the choice of network interface are explored. This way, the user equipment itself would be able to initiate handovers from one radio access technology to another depending on each particular service and on the environmental conditions, and hence it could extend its battery life. The work has focused in energy efficient vertical handovers (VHOs) between Long-Term Evolution (LTE) and Wi-Fi networks. The rapid growth and increasing interest in LTE networks have been the main reasons why these networks have been chosen over Third Generation Mobile Networks. Nevertheless this work can be easily extended to other radio access technologies such as WiMAX (Worldwide Interoperability for Microwave Access) or UMTS (Universal Mobile Telecommunication System). During the thesis project, the potential energy savings via VHOs depending on the type of service have been studied, as well as the different processes involved in a handover decision process. In order to do so, an energy consumption profile of each interface has been built, the different services have been modeled, and a heterogeneous scenario with Wi-Fi and LTE networks has been simulated. The thesis presents how these savings change within each service and with the environmental conditions (network load, interferences). The results show that large energy savings can be achieved. Nevertheless, the potential savings for each different user device can significantly differ. The VHO decision process includes two main aspects that need further study: investigating energy efficient ways of discovering accessible Wi-Fi access points and measuring the available throughput in each network at the moment of the decision. In addition, within LTE-Advanced and HetNets (Heterogeneous Networks), a lot of research regarding how LTE operators can offload traffic to smaller networks is being performed. These smaller networks consist basically of LTE micro cells and Wi-Fi. Both the energy savings and the potential energy expenses of offloading different kinds of traffic to a Wi-Fi network were also studied in this master’s thesis project, using the same approach described in the previous two paragraphs. / Enligt beräkningar så finns det nu mer än 1.08 miljarder smarta telefoner i världen, och ungefär 89% av dem används varje dag. Varje användare överför mer än 450 megabyte per månad i genomsnitt, antingen via cellulära mobilnät eller Wi-Fi. För närvarande är det användaren som avgör vilket av dessa interface som ska användas vid varje tidpunkt. I detta examensarbete utvärderas vilka energibesparingar som kan uppnås genom att automatisera valet av nätverksinterface. På detta vis skulle den mobila enheten själv utföra handover från en radioaccessteknik till en annan beroende på aktiva tjänster och på radioomgivningen, och därmed utöka batteriets livstid. Detta examensarbete fokuserar på vertikal handover mellan LTE och Wi-Fi nätverk. Den snabba tillväxten och det ökande intresset för LTE är den främsta anledningen till att LTE har valts istället för 3G. Det är dock möjligt att med små förändringar generalisera arbetet till andra radioaccesstekniker, till exempel WiMAX eller UMTS. De potentiella energibesparingarna genom vertikala handovers för olika typer av tjänster har studerats, liksom de olika stegen i handover-beslutsprocessen. För detta syfte har en energikonsumtionsprofil skapats för varje interface, de olika tjänsterna har modellerats och ett scenario med Wi-Fi- och LTE-nätverk har simulerats. Denna rapport beskriver hur dessa energibesparingar ändras för varje tjänstetyp och med ändringar av omgivningen (nätverkslast och interferens). Resultaten har visat att stora energibesparingar kan uppnås, även om dessa besparingar kan variera mycket för olika UEs. Beslutet om vertikal handover inkluderar två huvudsakliga aspekter som kräver fortsatta studier: energieffektiva metoder för att upptäcka tillgängliga WiFi-accesspunkter som går att ansluta sig till och mätning av den upplevda datahastigheten i varje nätverk före beslutet om vertikal handover tas. Parallelt med detta examensarbete pågår omfattande studier om hur mobiloperatörer kan avlasta datatrafik till basstationer med kortare räckvidd. Dessa småskaliga nätverk förväntas bestå av LTE mikro/pico celler och/eller Wi-Fi nätverk. Detta examensarbete inkluderar även studier av de potentiella energibesparingar eller energikostnader för att avlasta olika slags trafik till Wi-Fi nätverk.