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Algoritmo de alocação dinâmica de largura de faixa para redes de comunicação móvel celular; Dynamic bandwidth allocation algorithm for mobile communication networks

Queiroz, Eduardo Martinelli Galvão de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/03/2008 Português
Relevância na Pesquisa
76.11%
O crescente aumento da demanda de tráfego nas redes celulares vem aumentando a necessidade de uma melhor utilização dos recursos do sistema, já que sua expansão é custosa. Nas estações rádio base (ERB), a disponibilidade de largura de faixa de freqüências é limitada e desta maneira, em uma rede de comunicação móvel celular, o controle de admissão de chamadas exerce grande influência no desempenho do sistema, pois determina a utilização de banda das ERBs e se uma determinada quantidade de recursos (banda) será alocado ou não para uma determinada chamada. O desempenho da rede pode ser atrelado a determinados parâmetros, como a probabilidade de bloqueio de novas chamadas, probabilidade de bloqueio de chamadas handoff e a utilização de banda da rede. Este trabalho propõe um controle de admissão de chamadas que, no atendimento de uma chamada, faz o empréstimo de banda de chamadas em andamento na célula no caso de banda insuficiente. O sistema adota um mecanismo heurístico que determina a banda disponível para novas chamadas conforme os valores de certos parâmetros do sistema. O empréstimo de banda é realizado em chamadas em andamento nas células até níveis mínimos estabelecidos para cada tipo de chamada...

Analise de desempenho dos sistemas moveis celulares 2G, 2,5G e 3G; Performance analysis of 2G, 2.5G and 3G cellular mobile systems

Carlos Henrique Rodrigues de Oliveira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 12/08/2005 Português
Relevância na Pesquisa
36.09%
Este trabalho de tese estuda e analisa o desempenho dos sistemas móveis celulares GSM de segunda geração (2G), GPRS de segunda geração intermediária (2,5G) e CDMA2000 de terceira geração (3G). Na primeira parte deste trabalho de tese são avaliadas estratégias de compartilhamento dos canais de comunicação utilizados pelos sistemas GSM e GPRS, em busca daquela que resulte no menor impacto na qualidade dos serviços prestados por ambas as redes. Para esta avaliação, e como contribuição deste trabalho de tese, são desenvolvidos algoritmos aplicados em um simulador de eventos discretos desenvolvido em linguagem de programação C/C++. Os resultados das simulações mostram que a reserva de canais exclusivos ao sistema GPRS apresenta degradação na qualidade de serviço prestado pelo sistema GSM e que a melhor estratégia de compartilhamento é utilizar os canais de comunicação para o sistema GPRS nos momentos em que estes canais não são usados pelo sistema GSM. Na segunda parte deste trabalho de tese são feitas análises de desempenho dos sistemas móveis celulares de terceira geração, CDMA2000 lxRTT e CDMA2000 lxEVDO, baseadas na qualidade do serviço prestado por estas redes operando com várias aplicações simultâneas fim-a-fim entre cliente e servidor. Técnicas de detecção multiusuário e de antenas adaptativas são utilizadas na recepção destas aplicações e é avaliada a nova qualidade de serviço. Para estas análises de desempenho e como contribuição deste trabalho de tese...

Future Directions of Personal Multimedia Communication Space: Investigation of Wireless Markets, Systems, and Standards in Regard to Multimedia over IP

Englund, Christer
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Formato: 501452 bytes; 808287 bytes; 409179 bytes; 560718 bytes; application/pdf; application/pdf; application/pdf; application/pdf
Português
Relevância na Pesquisa
36.17%
Mobile communications and Internet based computer communications are the two fastest growing areas of communications indicating an enormous business potential in the intersection of these two domains. Since the introduction of cellular networks, wireless communications have focused on speech only, while mobile data has played a minor role. This paradigm is likely to change drastically in the near future. A new phenomenon, reflected by a nomadic lifestyle, is spreading all over the industrialized countries. Clear evidence of this is discernible particularly in Japan and Scandinavia. Nomadic lifestyle suggests that we are now at the advent of a new era of mobile communications, which will be fueled by rapid evolution of key technologies such as mobile computing, low-power consuming RISC and signal processor technologies, wireless channel aggregation, wireless packet data, and Internet based multimedia communications. The current trend of network evolution implies that the Internet will serve as a core for future service provision, whereas traditional telecommunication networks offer access paths to those services. Internet telephony reflects the beginning of a new communication era, which is characterized by running real-time applications over Internet/Intranet based computer communication infrastructure. We can envision that soon they not only contain speech...

MOBILITY MODELS, MOBILE CODE OFFLOADING, AND P2P NETWORKS OF SMARTPHONES ON THE CLOUD

KOSTA, SOKOL
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.12%
It was just a few years ago when I bought my first smartphone. And now, (almost) all of my friends possess at least one of these powerful devices. International Data Corporation (IDC) reports that smartphone sales showed strong growth worldwide in 2011, with 491.4 million units sold – up to 61.3 percent from 2010. Furthermore, IDC predicts that 686 million smartphones will be sold in 2012, 38.4 percent of all handsets shipped. Silently, we are becoming part of a big mobile smartphone network, and it is amazing how the perception of the world is changing thanks to these small devices. If many years ago the birth of Internet enabled the possibility to be online, smartphones nowadays allow to be online all the time. Today we use smartphones to do many of the tasks we used to do on desktops, and many new ones. We browse the Internet, watch videos, upload data on social networks, use online banking, find our way by using GPS and online maps, and communicate in revolutionary ways. Along with these benefits, these fancy and exciting devices brought many challenges to the research area of mobile and distributed systems. One of the first problems that captured our attention was the study of the network that potentially could be created by interconnecting all the smartphones together. Typically...

Convergence in Information and Communication Technology : Strategic and Regulatory Considerations

Singh, Rajendra; Raja, Siddhartha
Fonte: World Bank Publicador: World Bank
Português
Relevância na Pesquisa
36.21%
This book is a compilation of two recently completed works on the convergence of information and communication technology (ICT) (Singh and Raja 2008, 2009). Since then, convergence, the eroding of boundaries among previously separate ICT services, networks, and business practices, has accelerated and deepened. At the time these reports were written, convergence was already a reality and was picking up pace in low-income countries, as in the rest of the world. Now, as this introduction summarizes, broadband networks are reaching deeper into previously unserved areas. The growing number of people connected to broadband networks are consuming, sharing, and creating new multimedia content and applications. And they are doing this on handheld and portable devices that are less costly and do more than before. All sorts of users, governments, businesses, individuals, and ICT firms, are looking to cut costs while capturing greater value. Taken together, these trends indicate that convergence is set to accelerate even through the ongoing global economic downturn. Countries that enable convergence through appropriate policy and regulatory responses will realize significant benefits in terms of expanded access...

Broadband for Africa : Developing Backbone Communications Networks

Williams, Mark D. J.
Fonte: World Bank Publicador: World Bank
Português
Relevância na Pesquisa
36.11%
Many countries in Sub-Saharan Africa see information and communication technology (ICT) as a necessary foundation for long-term economic development. While the region has been very successful in increasing access to basic voice communications, there has been no comparable improvement in broadband connectivity. In fact, the broadband access gap between Sub-Saharan Africa and the rest of the world is getting wider just as the gap in basic voice communications is getting smaller. Increasing access to broadband connectivity is therefore emerging as a high priority for policy makers across the continent. This book begins with a brief review of the ICT market and considers the extent of demand for broadband and the ICT services that high-capacity backbone networks make possible. This is followed by a review of the existing coverage of backbone networks in the region, a discussion of how this compares with other parts of the world, and an analysis of the possible explanations for the current pattern of network development. Finally...

Broadband Wireless Access in Egypt

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Português
Relevância na Pesquisa
36.27%
This paper discusses current and future developments in wireless technology and infastructure in Egypt. One of the important regulatory decisions made in Egypt is that policy related to broadband wireless will be technology neutral. Consequently, the regulator cannot decide about which operators should use specific technologies. This approach is beneficial for the overall development of the market and deployment of networks because: It allows operators and service providers to decide on which technology or mix of technologies is best for given service and market requirements, budget outlays, and deployment scenarios. Such an approach promotes technical and economic efficiency since each service providerwill attempt to maximize revenues and their subscriber base. The flexibility allows the regulator to ensure that the market can deploy the latest technology with the least regulatory overhead. Allowing only one technology into the market place will restrict the range of choices available to consumers.

Challenges and Opportunities of Mobile Phone-Based Data Collection : Evidence from South Sudan

Demombynes, Gabriel; Gubbins, Paul; Romeo, Alessandro
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
Relevância na Pesquisa
35.97%
The proliferation of mobile phones in developing countries has generated a wave of interest in collecting high-frequency socioeconomic surveys using this technology. This paper considers lessons from one such survey effort in a difficult environment -- the South Sudan Experimental Phone Survey, which gathered data on living conditions, access to services, and citizen attitudes via monthly interviews by phones provided to respondents. Non-response, particularly in later rounds of the survey, was a substantial problem, largely due to erratic functioning of the mobile network. However, selection due to non-response does not appear to have markedly affected survey results. Response rates were much higher for respondents who owned their own phones. Both compensation provided to respondents in the form of airtime and the type of phone (solar-charged or traditional) were varied experimentally. The type of phone was uncorrelated with response rates and, contrary to expectation, attrition was slightly higher for those receiving the higher level of compensation. The South Sudan Experimental Phone Survey experience suggests that mobile phones can be a viable means of data collection for some purposes...

Mobile at the Base of the Pyramid : Ghana, Mozambique, Nigeria, Zambia Summary Report

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Português
Relevância na Pesquisa
36.08%
This report assesses existing mobile application (app) business models targeted at, or suitable for, people living at the base of the pyramid (BoP). The report addresses specific pain points for app developers and provides practical, actionable advice. Its recommendations are specific to each of the four countries: Ghana, Mozambique, Nigeria, and Zambia. While assessing the app markets in the four countries, it became clear that there is a wide range of business models. Each business model is unique to the sector and to the business problem the app is attempting to address. This report focuses on three areas common to all business models to provide maximum value for app developers. This report also presents a brief assessment of app incubators or hubs. These incubators play a significant role in supporting and advocating apps. However, this role is often only partially realized and this report makes recommendations to address this.

Directionality based preventive link maintenance scheme for mobile ad hoc networks

Jasani, Hetalkumar
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.94%
The purpose of this study was to design a preventive scheme using directional antennas to improve the performance of mobile ad hoc networks. In this dissertation, a novel Directionality based Preventive Link Maintenance (DPLM) Scheme is proposed to characterize the performance gain [JaY06a, JaY06b, JCY06] by extending the life of link. In order to maintain the link and take preventive action, signal strength of data packets is measured. Moreover, location information or angle of arrival information is collected during communication and saved in the table. When measured signal strength is below orientation threshold , an orientation warning is generated towards the previous hop node. Once orientation warning is received by previous hop (adjacent) node, it verifies the correctness of orientation warning with few hello pings and initiates high quality directional link (a link above the threshold) and immediately switches to it, avoiding a link break altogether. The location information is utilized to create a directional link by orienting neighboring nodes antennas towards each other. We call this operation an orientation handoff, which is similar to soft-handoff in cellular networks. ^ Signal strength is the indicating factor, which represents the health of the link and helps to predict the link failure. In other words...

Accessing the Internet through Moving Networks

Soto, Ignacio; Bernardos, Carlos J.; Zapata, Santiago; Dirk, Hugo von; Sargento, Susana
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência Formato: application/pdf
Publicado em /07/2007 Português
Relevância na Pesquisa
45.94%
The success of cellular communications networks shows the interest of users in mobility. Host mobility support in IP networks is a first step in the adaptation of these networks to the needs of users in this field. But, there exists also the need of supporting the movement of a complete network that changes its point of attachment to the fixed infrastructure. This paper describes the architecture designed in the EU DAIDALOS II project to provide Internet access through moving networks. The designed moving networks architecture support the following main features: Route Optimisation, Multicast traffic delivery, security and authentication integration, end-to-end QoS and interaction with Localised Mobility Management solutions.; Poster at IST Mobile & Wireless Communications Summit 2007, Budapest, Hungary, 1-5 July 2007.

On the physical layer security in large scale cellular networks

Wang, He; Zhou, Xiangyun; Reed, Mark C
Fonte: IEEE Publicador: IEEE
Tipo: Conference paper Formato: 6 pages
Português
Relevância na Pesquisa
35.97%
This paper studies the information-theoretic secrecy performance in large-scale cellular networks based on a stochastic geometry framework. The locations of both base stations and the mobile users are modeled as independent two-dimensional Poisson point processes. We consider a key feature of the cellular network, namely, information exchange between base stations, and characterize its impact on the achievable secrecy rate of an arbitrary downlink transmission with a certain portion of the mobile users acting as potential eavesdroppers. In particular, analytical results are presented under diverse assumptions on the availability of eavesdroppers' location information at the serving base station, which captures the benefit from the exchange of mobile users' location information between base stations.; H. Wang is with the Australian National University and NICTA. NICTA is funded by the Australian Government as represented by the Department of Broadband, Communications and the Digital Economy and the Australian Research Council through the ICT Centre of Excellence program. This work was supported by the Australian Research Councils Discovery Projects funding scheme (Project No. DP110102548 and Project No. DP130101760).

Segurança em sistemas de comunicação pessoal : um modelo de arquitetura de protocolos para a interconexão de sistemas heterogêneos; Security in personal communications systems. one model of protocol architecture for the interworking of heterogeneous systems

Luna Galiano, Herbert
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
36.09%
A evolução dos sistemas de comunicação sem fio ou wireless apresentam até agora três gerações em menos de duas décadas. Fazendo parte desta evolução estão os sistemas de telefonia celular e os emergentes Sistemas de Comunicação Pessoal ou PCS (Personal Communications Systems). Este trabalho visa apresentar duas questões importantes na evolução destes sistemas, primeiro a questão da segurança e segundo a questão da interconexão com redes heterogêneas. No trabalho, abordando a questão de segurança, são estudados, analisados e comparados os mecanismos de autenticação e privacidade implementados nos atuais padrões de telefonia celular digital e analógico, como sistemas AMPS (celular analógico americano), USCD (celular digital americano) e GSM (celular digital europeu). São identificadas a vulnerabilidade e os fraudes mais comuns nestes sistemas. Também são analisados as propostas das recentes pesquisas e o state of art em termos de segurança, para os sistemas PCS emergentes. Como conclusão apresentado um quadro comparativo resumindo as principais características de segurança adotados pelos sistemas abordados neste estudo. Uma vez apresentado os aspectos de segurança em forma isolada para cada um dos sistemas acima mencionados...

Green Cellular Wireless Networks: Where to Begin?

Ayanoglu, Ender
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/10/2012 Português
Relevância na Pesquisa
45.89%
Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this note, we describe the sources of the inefficiencies in such networks. First we quantify how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer as well as higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in wireless cellular networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously.

Integrated Solution Scheme for Handover Latency Diminution in Proxy Mobile IPv6

Hassan, Md. Mahedi; Hoong, Poo Kuan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/08/2011 Português
Relevância na Pesquisa
36%
Recent trends show that there are swift developments and fast convergence of wireless and mobile communication networks with internet services to provide the quality of ubiquitous access to network users. Most of the wireless networks and mobile cellular networks are moving to be all IP based. These networks are connected through the private IP core networks using the TCP/IP protocol or through the Internet. As such, there is room to improve the mobility support through the Internet and support ubiquitous network access by providing seamless handover. This is especially true with the invention of portable mobile and laptop devices that can be connected almost everywhere at any time. However, the recent explosion on the usage of mobile and laptop devices has also generated several issues in terms of performance and quality of service. Nowadays, mobile users demand high quality performance, best quality of services and seamless connections that support real-time application such as audio and video streaming. The goal of this paper is to study the impact and evaluate the mobility management protocols under micro mobility domain on link layer and network layer handover performance. Therefore, this paper proposes an integration solution of network-based mobility management framework...

Ontology for Cellular Communication

Neji, Hasni
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/07/2012 Português
Relevância na Pesquisa
55.86%
The lack of interoperability between mobile cellular access networks has long been a challenging obstacle, which telecommunication engineering is trying to overcome. In second generation networks for example, this problem lies in the fact that there are multiple standards. Each of these standards can operate in the same frequency range. However, each utilizes a different Radio Technology and Modulation Scheme, which are characteristics of the standard. Therefore, the lack of interoperability in 2G occurs because of the lack of standardization. Interoperability within 3G networks is limited to a few operating modes using different Radio Transmission Technologies that are not inter-operable. Thus, interoperability remains an issue for 3G. 4G technology even being successful in its various trials cannot guarantee the interoperability. This is within each network generation; meanwhile between heterogeneous network generations the situation seems to be worst. This approach is first to analyze the structure, inputs, and outputs of three different cellular technologies, performing a domain analysis (of this subset of technologies) and producing a feature model of the domain. Finally, we sought to build an ontology capable of providing a common view of the domain...

Survey of Latest Wireless Cellular Technologies for Enhancement of Spectral Density at Reduced Cost

Jain, R. K.; Katiyar, Sumit; Agrawal, N. K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/10/2011 Português
Relevância na Pesquisa
45.97%
The future of mobile wireless communication networks will include existing 3rd generation, 4th generation (implemented in Japan, USA, South Korea etc.), 5th generation (based on cognitive radio which implies the whole wireless world interconnection & WISDOM - Wireless innovative System for Dynamic Operating Megacommunications concept), 6th generation (with very high data rates Quality of Service (QoS) and service applications) and 7th generation (with space roaming). This paper is focused on the specifications of future generations and latest technologies to be used in future wireless mobile communication networks. However keeping in view the general poor masses of India, some of the future generation technologies will be embedded with 2G and 2.5G so that general masses may get the advantage of internet, multimedia services and the operators may get proper revenues with little extra expenditure in the existing mobile communication networks.; Comment: 7 pages, 4 figures, international journal

Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks

Davaslioglu, Kemal; Ayanoglu, Ender
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/01/2015 Português
Relevância na Pesquisa
45.91%
Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this paper, we describe the sources of the inefficiencies in such networks. First we present results of the studies on how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer as well as at higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in cellular wireless networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously. We then investigate potential methods to reduce this inefficiency and quantify their individual contributions. By a consideration of the combination of all potential gains, we conclude that an improvement in energy consumption in cellular wireless networks by two orders of magnitude...

Are low cost accountability, communications, and management systems for emergency first responders using 3G and 4G cellular technologies feasible?

Coleman, Kenneth
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
46.02%
Reliable, easily deployed communication networks are a necessity for emergency responders as the coordination of their efforts and their safety depend on it. As a volunteer firefighter, this researcher is aware of the shortcomings of the current communication technologies presently deployed, and the risks it poses to firefighters. Some studies have proposed deployment of sophisticated hybrid, mesh networks and mobile ad hoc networks that allow for location tracking, environment and personnel vital signs monitoring, and data communications. Unfortunately the cost of these systems and required training in use of the equipment inhibits their adoption and wide scale deployment across the nation's emergency responder agencies. We are surrounded by secure, reliable cellular network technologies that meet our voice and data communication needs, yet current studies focus on building network infrastructures from the ground up and discussing how to address the security and performance issues of their proposed networks. This study proposes the use of the existing cellular network architecture already in place across the nation as a foundation to explore the feasibility of a low cost communication, management and accountability system utilizing 3G and 4G technologies and architecture.

Assisted GPS solution in cellular networks

Lissai, Gidon
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.05%
The ‘Wireless Enhanced 911’ rules, which were issued in 1996, state that the position of a mobile device should be sent to Public Safety Answering Point (‘PSAP’) once a 9-1-1 call takes place from it. The rules imposed the cellular carriers to integrate a technology into their networks so that the mobile device location can be transferred once a 9-1-1 call is made. One of the chosen technologies was the Global Positioning System (GPS). The solution suggests integrating a GPS receiver into every cellular device. But the GPS receiver, as a stand alone solution, has some major performance limitations in regards to the Wireless Enhanced 911 requirements. The Assisted GPS (A-GPS) technology improves the GPS receiver performances. It reduces the time it takes the receiver to calculate its location. It also enhances the receiver’s reception sensitivity and improves the calculated position accuracy. With the A-GPS technology, the GPS receiver solution becomes compatible with the rules requirements. Two of the four large wireless carriers in the U.S. had chosen the A-GPS as their location solution in their networks. The A-GPS technology became an important part of the cellular industry. The intention of the thesis is to explore the A-GPS solution and to show its necessity in today’s GPS-based solutions. The following aspects are reviewed in the thesis – how the A-GPS solution works...