With advances in wireless technology and mobile devices, the number of mobile users using multimedia services has increased significantly in recent years. Mobile devices can be connected and roam on heterogeneous wireless networks. The IEEE 802.21 group has designed a Media Independent Handover (MIH) standard to ensure seamless Vertical Handover (VHO) in heterogeneous networks. However, the standard currently depends on features of the network (e.g. the type of network and available bandwidth) to achieve seamless VHO. This approach is limited, as it does not consider how a Quality of Experience (QoE) can be provided and maintained for customers when delivering multimedia services in heterogeneous wireless networks. The aim of the project is to develop a novel QoE-driven VHO management framework for providing and maintaining an appropriate level of QoE of multimedia services as the mobile user’s actual requirements in heterogeneous wireless networks. A QoE-driven VHO algorithm is more efficient for maintaining this acceptable QoE of multimedia services than traditional network-based or QoS-based VHO algorithms. There are three main contributions during this project. Firstly, A thorough evaluation of the performance of voice and video services via Skype was carried out in terms of the QoE metric (i.e. MOS). This work identified the impact of video content and packet loss on the QoE metric for voice and video communication services over wireless networks. Secondly, a QoE-driven VHO algorithm was developed to provide and maintain an acceptable QoE of mobile video services for mobile users. Compared to a traditional network-based VHO algorithm, this algorithm can provide better QoE and maintain acceptable QoE. Lastly, the User-centric QoE-driven (UCQoE) VHO framework to provide satisfactory QoE of multimedia services according to the mobile user’s requirements. The framework allows users to set their own preferences (e.g. quality-guarantee or cost-free) and carry out VHO operations accordingly. The evaluation showed that the proposed framework can provide a better QoE for delivered video services than QoS-based and network-based VHO algorithms. Furthermore, the proposed framework can be used to avoid unnecessary cost of mobile data when the option of cost-free is preferred by the user. During this project, three international conference papers had been published and a journal paper has been submitted to IEEE Transactions on Mobile Computing. The main contribution-UCQoE VHO management framework can be developed to maintain QoE of all mobile services in the future.

No / In this paper, the requirements for personal environments mobility are addressed from terminal and network perspectives. Practical mobility and Quality of Service (QoS) aware solutions are proposed for a heterogeneous network, comprising of satellite and terrestrial access networks connected to an IP core network. The aim, in adopting a heterogeneous environment, is to provide global, seamless service coverage to a specific area, allowing access to services independently of location. An important assumption is that nomadic user terminals attached to a particular segment should be able to exchange information with any other terminal connected to the network. This is to ensure transparency of device technology. Different communication scenarios are investigated in support of IPv4 and IPv6 operating on user platforms and over access segments. The heterogeneous network necessitates the need to perform handover between access segments to enable coverage extension and seamless connectivity. Handover procedures are analyzed, and an approach is presented that enables various operation and segment specific parameters to be taken into account when deciding upon the need to perform handover and in selecting the optimum access segment. In order to ensure transparency of network technology, the need for end-to-end QoS support is discussed, bearing in mind the deployment of both IntServ and DiffServ enabled routers in the core network. Following this, a new admission control scheme, named Gauge&Gate Reservation with Independent Probing (GRIP), is proposed. The paper concludes with a description of a laboratory testbed, which has been developed in order to verify the presented procedures, together with performance measurements of the handover and the GRIP algorithms.

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

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.

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

Third Generation (3G) wireless networks have been well studied and optimized with traditional radio resource management techniques, but still there is room for improvement. Cognitive radio technology can bring significantcant network improvements by providing awareness to the surrounding radio environment, exploiting previous network knowledge and optimizing the use of resources using machine learning and artificial intelligence techniques. Cognitive radio can also co-exist with legacy equipment thus acting as a bridge among heterogeneous communication systems. In this work, an approach for applying cognition in wireless networks is presented. Also, two machine learning techniques are used to create a hybrid cognitive engine. Furthermore, the concept of cognitive radio resource management along with some of the network applications are discussed. To evaluate the proposed approach cognition is applied to three typical wireless network problems: improving coverage, handover management and determining recurring policy events. A cognitive engine, that uses case-based reasoning and a decision tree algorithm is developed. The engine learns the coverage of a cell solely from observations, predicts when a handover is necessary and determines policy patterns, solely from environment observations. / Ph. D.

Integrating unmanned aerial vehicles (UAVs) as aerial user equipments (UEs) into cellular networks is now considered as a promising solution to provide extensive wireless connectivity for supporting UAV-centric commercial or civilian applications. However, the co-existence of UAVs with conventional terrestrial UEs is one of the primary challenges for this solution. Flying at higher altitudes with maneuverability advantage, UAVs are able to establish line-of-sight (LoS) connectivity with more base stations (BSs) than terrestrial UEs. Although LoS connectivity reduces the communication delay of UAVs, they also simultaneously increase the interference that UAVs cause to terrestrial UEs. In scenarios involving multiple UAVs, LoS connectivity can even lead to interference issues among themselves. In addition, LoS connectivity leads to extensive overlapping coverage areas of multiple BSs for UAVs, forcing them to perform frequent handovers during the flight if the received signal strength (RSS)-based handover policy is employed. The trajectories and BS associations of UAVs, along with their radio resource allocation are essential design parameters aimed at enabling their seamless integration into cellular networks, with a particular focus on managing interference levels they generate and reducing the redundant handovers they performe. Hence, this thesis designs two joint trajectory and handover management approaches for single-UAV and multi-UAVs scenarios, respectively, aiming to minimize the weighted sum of three key performance indicators (KPIs): transmission delay, up-link interference, and handover numbers. The approaches are based on deep reinforcement learning (DRL) frameworks with dueling double deep Q-network (D3QN) and Q-learning with a MIXer network (QMIX) algorithms being selected as the training agents, respectively. The choice of these DRL algorithms is motivated by their capability in designing sequential decision-making policies consisting of trajectory design and handover management. Results show that the proposed approaches effectively address the aforementioned challenges while ensuring the low transmission delay of cellular-connected UAVs. These results are in contrast to the performance of benchmark scheme, which directs UAVs to follow the shortest path and perform handovers based on RSS. Specifically, when considering the single-UAV scenario, the D3QN-based approach reduces the up-link interference by 18% and the handover numbers by 90% with a 59% increase in transmission delay as compared to the benchmark. The equivalent delay increase is 15 microseconds, which is considered negligible. For the multi-UAVs scenario, the QMIX-based approach jointly optimizes three performance metrics as compared to the benchmark scheme, resulting in a 70% decrease in interference, a 91% decrease in handover numbers, and a 47% reduction in transmission delay. It is noteworthy that an increase of UAVs operating within the same network leads to performance degradation due to UAVs competing for communication resources and mutual interference. When transitioning from the single-UAV scenario to the multi-UAVs scenario, the performance of the benchmark scheme experiences a significant decline, with an increase of 199% in interference, 89% in handover numbers, and 652% in transmission delay. In contrast, the proposed QMIX algorithm effectively coordinates multiple UAVs, mitigating performance degradation and achieving performance similar to the D3QN algorithm applying in the single-UAV scenario: an interference increase of 9%, a handover numbers increase of 9% and a delay increase of 152%. The delay increase is attributed to the reduced communication resources available to each individual UAVs, given the constant communication resources of the network. / Att integrera obemannade flygfordon (UAV) som flyganvändarutrustning (UE) i cellulära nätverk anses nu vara en lovande lösning för att tillhandahålla omfattande trådlös anslutning för att stödja UAV-centrerade kommersiella eller civila tillämpningar. Men samexistensen av UAV med konventionella markbundna UE är en av de främsta utmaningarna för denna lösning. Flygande på högre höjder med manövrerbarhetsfördelar kan UAV:er etablera siktlinje (LoS)-anslutning med fler basstationer (BS) än markbundna UE. Även om LoS-anslutning minskar kommunikationsfördröjningen för UAV:er, ökar de samtidigt störningen som UAV:er orsakar för markbundna UE. I scenarier som involverar flera UAV:er kan LoS-anslutning till och med leda till störningsproblem sinsemellan. Dessutom leder LoS-anslutning till omfattande överlappande täckningsområden för flera BS:er för UAV, vilket tvingar dem att utföra frekventa överlämningar under flygningen om den mottagna signalstyrkan (RSS)-baserad överlämningspolicy används. UAV:s banor och BS-associationer, tillsammans med deras radioresursallokering, är väsentliga designparametrar som syftar till att möjliggöra deras sömlösa integrering i cellulära nätverk, med särskilt fokus på att hantera störningsnivåer de genererar och minska de redundanta handovers de utför. Därför designar denna avhandling två gemensamma bana och handover-hanteringsmetoder för en-UAV-respektive multi-UAV-scenarier, som syftar till att minimera den viktade summan av tre nyckelprestandaindikatorer (KPI:er): överföringsfördröjning, upplänksinterferens och överlämningsnummer . Tillvägagångssätten är baserade på ramverk för djup förstärkning inlärning (DRL) med duellerande dubbla djupa Q-nätverk (D3QN) och Q-lärande med ett MIXer-nätverk (QMIX) algoritmer som väljs som träningsagenter. Valet av dessa DRL-algoritmer motiveras av deras förmåga att utforma sekventiella beslutsfattande policyer som består av banadesign och handover-hantering. Resultaten visar att de föreslagna tillvägagångssätten effektivt tar itu med ovannämnda utmaningar samtidigt som de säkerställer den låga överföringsfördröjningen för mobilanslutna UAV:er. Dessa resultat står i kontrast till prestanda för benchmark-schemat, som styr UAV:er att följa den kortaste vägen och utföra överlämningar baserat på RSS. Närmare bestämt, när man överväger singel-UAV-scenariot, minskar det D3QN tillvägagångssättet upplänksinterferensen med 18% och överlämningssiffrorna med 90% med en 59% ökning av överföringsfördröjningen jämfört med riktmärket. Den ekvivalenta fördröjningsökningen är 15 mikrosekunder, vilket anses vara försumbart. För scenariot med flera UAV:er optimerar det QMIX-baserade tillvägagångssättet tillsammans tre prestandamått jämfört med benchmark-schemat, vilket resulterar i en 70% minskning av störningar, en 91% minskning av överlämningssiffror och en 47% minskning av överföringsfördröjningen. Det är anmärkningsvärt att en ökning av UAV:er som arbetar inom samma nätverk leder till prestandaförsämring på grund av UAV:er som konkurrerar om kommunikationsresurser och ömsesidig störning. Vid övergången från scenariot med en UAV till scenariot med flera UAV, upplever prestanda för benchmark-schemat en betydande nedgång, med en ökning på 199% av störningar, 89% i överlämnandetal och 652% i överföringsfördröjning. Däremot koordinerar den föreslagna QMIX-algoritmen effektivt flera UAV, vilket minskar prestandaförsämring och uppnår prestanda liknande D3QN-algoritmen som tillämpas i single-UAV-scenariot: en störningsökning på 9%, en ökning av antalet överlämningar med 9% och en fördröjningsökning på 152%. Ökningen av fördröjningen tillskrivs de minskade kommunikationsresurserna tillgängliga för varje enskild UAV, givet nätverkets konstanta kommunikationsresurser.