Academic literature on the topic 'Mobile cellular communication networks'

COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>Nos últimos anos, considerável debate tem ocorrido a respeito do tema gerência de mobilidade, face à necessidade de se fazer uso judicioso dos recursos de sinalização destinados para esse fim no âmbito de sistemas de comunicação móvel celular e de sistemas de comunicação pessoal (PCS). Dentre as estratégias de gerência de mobilidade, destaca-se a utilização do conceito de áreas de registro, amplamente empregadas a partir dos sistemas de 2a. geração, e permitindo reduzir o consumo de recursos devido a atualizações de localização. Outro conceito, o de áreas de paging, tem também se tornado bastante difundido, propiciando a economia de recursos gastos na procura de terminais móveis por ocasião de tentativas de completamento de chamadas para estes terminais. Este trabalho inicia-se com discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se no contexto do trabalho o modelo baseado em fluxo de fluídos e o modelo gravitacional. O problema de particionamento em áreas de localização (LAPP) é então tratado como um problema de particionamento de grafos, cuja elevada complexidade enseja a utilização de heurísticas capazes de propiciar a obtenção de soluções próximas da ótima. As heurísticas propostas destinam-se ao caso mais comum, em que áreas de localização são coincidentes com áreas de paging. Com base em metodologia utilizada para o LAPP, são propostas soluções para um outro problema, o ISHMP (Inter-Switch Handover Minimization Problem), cuja importância se prende não só ao elevado consumo de recursos mas também aos atrasos impostos pelo sistema aos usuários quando estes trocam de área de Mobile Switching Center. Assim, reduzir ao máximo a ocorrência de tais eventos é vantajoso tanto do ponto de vista do usuário quanto do sistema. As heurísticas propostas são essencialmente as mesmas para ambos os problemas, e mostram superioridade em termos de qualidade das soluções obtidas quando comparadas com propostas de outros autores, através de casos-padrão publicados na literatura e de testbed construído especialmente para a comparação. Apresenta-se ainda discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se o modelo baseado em fluxo de fluidos e o modelo gravitacional. O trabalho apresenta também estudo relativo às cargas de sinalização que ocorrem tnato na rede fixa (incluindo o tráfego de consultas e atualizações sobre as bases de dados) quanto na interface aérea. No apêndice, considerando o grafo que modela a rede celular, apresenta-se comprovação formal da conversão de pesos de nós e de arestas em novos pesos de arestas, permitindo o tratamento dos dois problemas de particionamento aqui abordados como problemas de edgepartitioning puros.<br>In the past few years there hás been considerable debate over the question of mobility management in móbile cellular communication networks, due to the need of using the signaling system resources in a careful way. Among the strategies of location management, the utilization of registration areas has been difunded since the emergence of the second generation mobile communication systems, allowing to reduce the resource consumption due to location updates. Another concept, named paging areas, has also been extensively employed, allowing to save resources utilized localization of mobile terminals during the call setup for mobile stations. Initially, the Location Area Partitioning Problem (LAPP) is treated as a graph partitioning problem, largely recognized as NP-complete ([GARE 79], [LENG 90]) and leading to the utilization of heuristics, able to produce good sub-optimal solutions. The heuristics are proposed to solve the more usual case, where location areas are coincident with paging areas, and the frequency spectrum (radio resources). With the same methodology, another problem, named Inter- Switch Handover Minimization Problem (ISHMP), is adequately solved, being its relevance due to the elevated system resource consumption and to the severe delays imposed to users when their Mobile Switching Centers are changed. Thus, the diminution of the occurrence of such events id advantageous from both the user`s and the system`s points of view. The heuristics are eddentially the same for the two problems, and it is shown the superiority of the quality of the quality of the obtained solutions, when comparing them with other published results. The work also presents discussion about mobility models employed in the study of problems and techniques in the mobile communications area. Among such models, the fluid flow and the gravitational models are highlighted. A study concerning to the signaling load imposed to the fixed network (including queries and location update traffic over databases) and to the air interface is presented. Finally, starting from the average rate of mobile terminated calls and from a previously defined user impatience threshold, a new proposal for the definition of the optimal number of cells per paging area is presented.

<p>After more than two decades’ development, modern mobile cellular networks now have almost approached to the commercial level of fourth generation communication networks. For each of the mobile solutions, there are special attributes but also similarities compared to the other competitive solutions. We can also find relationships between the old generation solutions and the inheritors or innovations.</p><p>During the communicating session using any kind of existing mobile handset, the handover procedure is a very important one that may effect connection quality and also the phone call continuity. Nowadays, the mobile cellular networks have a trend to interact with LAN networks. They will co-exist and work together to support higher data rate over a wider coverage. Seamless handover proposals like Unlicensed Mobile Access (UMA) can support the heterogeneous handover between Global System for Mobile Communications (GSM) and Wireless (Wi-Fi) Network. Several Media Independent Handover (MIH) proposals can handle the vertical handover in the hybrid mobile data network environment such like between wireless local area network (WLAN) and Universal Mobile Telecommunications System (UMTS) by different solutions.</p>

Dans les années à venir, le trafic de données dans les réseaux cellulaires connaîtra une forte croissance en raison de l'augmentation de l’utilisation des moyens de télécommunications sans fil. Par conséquent, les opérateurs de réseaux mobiles visent à augmenter la capacité et la couverture de leurs réseaux afin de répondre à cette croissance. Dans ce contexte, l'un des principaux efforts est de densifier les réseaux Macrocells actuels par les Small cells afin d’offrir plus de couverture et de débit aux utilisateurs. Les antennes Small cells émettent de faibles puissances et sont souvent déployées à de faibles hauteurs. En conséquence, ils sont plus proches des utilisateurs, peuvent être déployés massivement mais génèrent également des inquiétudes chez les riverains. Les téléphones portables sont utilisés pour une grande variété d'utilisations qui nécessitent différentes quantités de données et de débit. Les applications de voix sur IP telles que Skype sont devenues très populaires car elles fournissent une communication vocale internationale peu onéreuse et peuvent être utilisées sur les appareils mobiles. Étant donné que les systèmes LTE ne prennent en charge que les services par paquets, le service vocal utilise la technologie voix sur LTE au lieu de la technologie « circuits » classique comme avec le GSM et UMTS.L'objectif principal de cette thèse est d'évaluer l'influence des nouvelles architectures des réseaux et usages sur l'exposition actuel du publique induite par les réseaux cellulaires. À cet égard, plusieurs campagnes de mesures ont été menées dans différentes villes et environnements.En ce qui concerne l'exposition aux champs électromagnétiques dans les réseaux hétérogènes, les résultats suggèrent qu'en déployant les Small cells, la puissance émise par le téléphone mobile, en raison de la proximité de l’antenne et par conséquent l’exposition global diminue. De plus, pour évaluer l'exposition EMF des utilisateurs indoor induite par les Small cells, deux modèles statistiques sont proposés pour les expositions montante et descendante induite dans un réseau hétérogène LTE.La dernière partie de cette thèse est consacrée à l'évaluation de l'exposition aux nouveaux types d'usages. Les résultats suggèrent que la puissance émise et la durée d'émission par un téléphone mobile dépendent fortement de l’usage et de la technologie du réseau. Les communications voix nécessitent un débit continu et généralement faible afin de maintenir la communication pendant l'appel. Au contraire, dans le cas de l’usage données, le téléphone mobile nécessite des débits plus élevés pour effectuer la tâche le plus rapidement. Par conséquent, pendant un appel voix, même si l'utilisateur utilise le téléphone portable pendant une durée relativement longue, la durée de l'exposition est moins longue car l'utilisation ne nécessite pas une grande quantité de données. Ainsi, le taux d'occupation temporelle de plusieurs types d'appels voix pour différentes technologies est évalué par les mesures<br>In coming years, there will be a sharp growth in wireless data traffic due to the increasing usage of mobile phones and implementation of IoT technology. Therefore, mobile network operators aim to increase the capacity of their networks, to provide higher data traffic with lower latency, and to support thousands of connections. One of the primary efforts toward these goals is to densify today's cellular Macrocell networks using Small cells to bring more coverage and higher network capacity. Small cell antennas emit lower power than Macrocells and are often deployed at low heights. As a consequence, they are closer to the user and can be implemented massively. The latter can result in an important raise in public concerns. Mobile phones are used on the one hand, for a large variety of data usages that require different amounts of data and throughput and on the other hand for making phone calls. Voice over IP applications such as Skype has become very popular since they provide cheap international voice communication and can be used on mobile devices. Since LTE systems only support packet services, the voice service uses Voice over LTE technology instead of classical circuit-switched voice technology as in GSM and UMTS. The main objective of this thesis is to characterize and analyse the influence of new network architectures and usages on the actual human exposure induced by cellular networks. In this regard, several measurement campaigns were carried out in various cities and environments. Regarding the EMF exposure in heterogeneous networks, results suggest that by implementing Small cells, the global exposure (i.e. exposure induced by mobile phone and base station antenna) reduces due to the fact that by bringing the antenna closer to the user the emitted power by mobile phone and the usage duration reduce owing to power control schemes implemented in cellular network technologies. However, the magnitude of exposure reduction depends on the location of the Small cell with respect to Macrocells. Moreover, to assess the EMF exposure of indoor users induced by Small cells, two statistical models are proposed for the uplink and downlink exposures in an LTE heterogeneous environment based on measurements. The last part of the thesis was devoted to the assessment of the exposure for new types of usages through measurements. Results suggest that the amount of uplink emitted power and the emission time duration by a mobile phone is highly dependent on the usage and network technology. Voice call communications require a continuous and generally low throughput in order to maintain the communication during the call. On the contrary, in data usage, the mobile phone requires higher data and throughput to perform the task as fast as possible. Therefore during a voice call even if the user is using the mobile phone for a relatively long time, the exposure time duration should be lower since the usage does not require high amounts of data. The temporal occupation rate for several types of voice calls for different technologies is assessed through measurements