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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
96.17%
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
56.2%
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...

A cross-layer approach to the downlink performance analysis and optimization of distributed antenna systems in multi-cell environments

Samano-Robles, R.; Gameiro, A.
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência
Português
Relevância na Pesquisa
25.93%
Distributed antenna systems (DAS) constitute one of the most attractive schemes to efficiently achieve the stringent quality of service demands of next generation wireless networks. However, existing works have been only focused on the analysis of the downlink of single-user DAS multi-cell networks with fixed node configurations and without considering the effects of upper layer algorithms. This paper partially fills this gap by presenting the performance analysis and optimization of the downlink of DAS systems in multi-cell environments with single and multiple users and with basic resource management algorithms. The cross-layer analysis and optimization is first carried out using a simplified system-level simulation tool which provides enough flexibility for the understanding of the basic rules of operation of the proposed algorithms. After this, the most promising algorithms are implemented in a full version of a system level simulator which has been especially developed for the accurate analysis and validation of 3G (third generation) and B3G (beyond 3G) radio access technologies. Our results show that under the appropriate allocation and management policies, distributed antenna systems efficiently counteract the main impairments of current cellular architectures.

Um estudo do aumento da capacidade de sistemas 3g WCDMA usando técnicas 3.5G de expansão do enlace reverso

Rodrigues, Eduardo Jorge Brito
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Elétrica; Automação e Sistemas; Engenharia de Computação; Telecomunicações Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Elétrica; Automação e Sistemas; Engenharia de Computação; Telecomunicações
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
36.02%
The introduction of new digital services in the cellular networks, in transmission rates each time more raised, has stimulated recent research that comes studying ways to increase the data communication capacity and to reduce the delays in forward and reverse links of third generation WCDMA systems. These studies have resulted in new standards, known as 3.5G, published by 3GPP group, for the evolution of the third generation of the cellular systems. In this Masters Thesis the performance of a 3G WCDMA system, with diverse base stations and thousand of users is developed with assists of the planning tool NPSW. Moreover the performance of the 3.5G techniques hybrid automatic retransmission and multi-user detection with interference cancellation, candidates for enhance the WCDMA uplink capacity, is verified by means of computational simulations in Matlab of the increase of the data communication capacity and the reduction of the delays in the retransmission of packages of information; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; A introdução de novos serviços digitais nas redes celulares, em taxas de transmissão cada vez mais elevadas, tem impulsionado recentes pesquisas que vêm estudando maneiras de aumentar a capacidade de transmissão de dados e diminuir os atrasos nos enlaces direto e reverso de sistemas de terceira geração WCDMA. Esses estudos têm resultado em novos padrões...

High speed internet access using cellular infrastructure

Chatziioannidis, Ioannis.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.07%
Approved for public release; distribution is unlimited; The way that the Internet is accessed has changed dramatically in recent years. In addition to wire line connections such as dial-up, xDSL, cable modems or optical fiber, wireless implementations are gaining market share based on technologies such as WiFi, WiMAX, MBWA, satellite and cell phone networks. This thesis examines the potential usage of providing Internet access through cellular infrastructure. The cellular evolution path from first generation (1G) to third generation (3G) and fourth generation (4G) systems is studied and presented. The most popular worldwide cellular voice and data network technologies are also described. Additionally, the Cingular Wireless network in Monterey, California is tested in terms of speed and reliability by providing Internet access to a laptop through a mobile phone. The analysis shows that, depending on the cellular network availability, throughput varied from 5 to 25 Kbps and Round Trip Time (RTT) averaged about 1 sec. Furthermore, it is shown that TCP Timestamps and the Explicit Congestion Notification (ECN) were implemented at the end hosts, thus increasing performance. The thesis concludes that as of July 2004, the 2.5G cellular data networks are a reasonable solution for those who need Internet access anywhere that a cell signal is available...

Comparing the capabilities and performance of the ultra high frequency follow-on system with the mobile user objective system

Matassa, Christopher K.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xvi, 53 p. : ill. (chiefly col.) ;
Português
Relevância na Pesquisa
25.83%
Approved for public release; distribution is unlimited.; The Mobile User Objective System (MUOS) is the DoD's next generation military Ultra High Frequency (UHF) Satellite Communication (SATCOM) system being designed to augment and eventually replace the currently oversubscribed UHF Follow-On (UFO) System. MUOS adapts a commercial third generation (3G) Wideband Code Division Multiple Access (WCDMA) cellular phone network architecture and combines it with geosynchronous satellites (in place of cell towers) with the goal of providing a more capable UHF SATCOM system. This research aims at investigating the differences between the legacy UFO and MUOS systems in terms of network performance and quality of service. Using modeling and simulation of both systems against input traffic loads of a hypothetical Joint Task Force, a comparative study of the performance and capabilities of each system is conducted to quantify the extent of MUOS improvements. The study finds that MUOS can tolerate a traffic demand rate of about 83 calls/messages per second whereas UFO saturates at roughly 4 calls/messages per second. MUOS's ability to offer a higher level of quality of service, assured access, and increased capacity will enable more tactical users to share timely information while reducing the uncertainty that they will be able to communicate with their intended recipient. Faster service data rates reduce delays in relaying information during time critical operations. The system represents a paradigm shift in UHF SATCOM from circuit-based...

Resource allocation in multi-user telecommunication networks

Qian, Dayou
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
35.89%
This dissertation discussed resource allocation mechanisms in several network topologies including infrastructure wireless network, non-infrastructure wireless network and wire-cum-wireless network. Different networks may have different resource constrains. Based on actual technologies and implementation models, utility function, game theory and a modern control algorithm have been introduced to balance power, bandwidth and customers' satisfaction in the system. ^ In infrastructure wireless networks, utility function was used in the Third Generation (3G) cellular network and the network was trying to maximize the total utility. In this dissertation, revenue maximization was set as an objective. Compared with the previous work on utility maximization, it is more practical to implement revenue maximization by the cellular network operators. The pricing strategies were studied and the algorithms were given to find the optimal price combination of power and rate to maximize the profit without degrading the Quality of Service (QoS) performance. ^ In non-infrastructure wireless networks, power capacity is limited by the small size of the nodes. In such a network, nodes need to transmit traffic not only for themselves but also for their neighbors...

Characterisation of noisy speech channels in 2G and 3G mobile networks

Leite, Bruno Daniel Moreira
Fonte: Instituto Politécnico do Porto Publicador: Instituto Politécnico do Porto
Tipo: Dissertação de Mestrado
Publicado em //2013 Português
Relevância na Pesquisa
46.1%
As the wireless cellular market reaches competitive levels never seen before, network operators need to focus on maintaining Quality of Service (QoS) a main priority if they wish to attract new subscribers while keeping existing customers satisfied. Speech Quality as perceived by the end user is one major example of a characteristic in constant need of maintenance and improvement. It is in this topic that this Master Thesis project fits in. Making use of an intrusive method of speech quality evaluation, as a means to further study and characterize the performance of speech codecs in second-generation (2G) and third-generation (3G) technologies. Trying to find further correlation between codecs with similar bit rates, along with the exploration of certain transmission parameters which may aid in the assessment of speech quality. Due to some limitations concerning the audio analyzer equipment that was to be employed, a different system for recording the test samples was sought out. Although the new designed system is not standard, after extensive testing and optimization of the system's parameters, final results were found reliable and satisfactory. Tests include a set of high and low bit rate codecs for both 2G and 3G, where values were compared and analysed...

Security in Carrier Class Server Applications for All-IP Networks

Chatel, Marc; Dagenais, Michel; Levert, Charles; Pourzandi, Makan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/12/2004 Português
Relevância na Pesquisa
55.84%
A revolution is taking place in telecommunication networks. New services are appearing on platforms such as third generation cellular phones (3G) and broadband Internet access. This motivates the transition from mostly switched to all-IP networks. The replacement of the traditional shallow and well-defined interface to telephony networks brings accrued flexibility, but also makes the network accordingly difficult to properly secure. This paper surveys the implications of this transition on security issues in telecom applications. It does not give an exhaustive list of security tools or security protocols. Its goal is rather to initiate the reader to the security issues brought to carrier class servers by this revolution.; Comment: Survey paper on the challenges of all IP networks in telecom applications

Radio Resource Allocation in LTE-Advanced Cellular Networks with M2M Communications

Zheng, Kan; Hu, Fanglong; Xiang, Wei; Dohler, Mischa; Wang, Wenbo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/10/2015 Português
Relevância na Pesquisa
45.92%
Machine-to-machine (M2M) communications are expected to provide ubiquitous connectivity between machines without the need of human intervention. To support such a large number of autonomous devices, the M2M system architecture needs to be extremely power and spectrally efficient. This article thus briefly reviews the features of M2M services in the third generation (3G) long-term evolution and its advancement (LTE-Advanced) networks. Architectural enhancements are then presented for supporting M2M services in LTE-Advanced cellular networks. To increase spectral efficiency, the same spectrum is expected to be utilized for human-to-human (H2H) communications as well as M2M communications. We therefore present various radio resource allocation schemes and quantify their utility in LTE-Advanced cellular networks. System-level simulation results are provided to validate the performance effectiveness of M2M communications in LTE-Advanced cellular networks.

The integration of ad hoc sensor and cellular networks for multi-class data transmission

Hu, Fei; Kumar, Sunil
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.01%
This paper targets mobile telemedicine applications that can be supported using third generation (3G) cellular networks, to provide highly flexible medical services. On the other hand, large-scale Ad hoc Sensor Networks (ASN), when deployed among mobile patients who may carry different kinds of micro-sensors to measure ECG, blood pressure, basal temperature or other physiological data, can provide a dynamic data query architecture to allow the medical specialists to monitor patients at any place. So far very little research has been conducted to explore the possibility of integrating ASN with mobile telemedicine. In this paper: 1. we suggest an integrated architecture that takes advantage of the low cost mobile sensor networks and 3G cellular networks to support multimedia medical calls with differentiated Quality-of-Service (QoS) requirements. 2. We propose a low-energy, distributed, concentric-zone-based data query mechanism that has the advantages of both proactive and reactive ad hoc routing algorithms to collect medical results from largescale mobile patients for medical specialists who use cellular network to report patient data to the medical center. 3. In order to minimize the ambulance wireless call-dropping rate, we adopt accurate resource reservation call admission control (CAC) scheme to allocate the necessary bandwidth in the destination cell. 4. In order to meet the QoS requirements of patients_ wireless calls...