1x Evolution-Data Optimized Revision A (1xEV-DO Rev. A) is a cellular communications standard that introduces key enhancements to the high data rate packet switched 1xEV-DO Release 0 standard. The enhancements are driven by the increasing demand on some applications that are delay sensitive and require symmetric data rates on the uplink and the downlink. Some examples of such applications being video telephony and voice over internet protocol (VoIP). The handoff operation is critical for delay sensitive applications because the mobile station (MS) is not supposed to lose service for long periods of time. Therefore seamless server selection is used in Rev. A systems. This research analyzes the performance of this handoff technique. A theoretical approach is presented to calculate the slot error probability (SEP). The approach enables evaluating the effects of filtering, hysteresis as well as the system introduced delay to handoff execution. Unlike previous works, the model presented in this thesis considers multiple base stations (BS) and accounts for correlation of shadow fading affecting different signal powers received from different BSs. The theoretical results are then verified over ranges of parameters of practical interest using simulations, which are also used to evaluate the packet error rate (PER) and the number of handoffs per second. Results show that the SEP gives a good indication about the PER. Results also show that when considering practical handoff delays, moderately large filter constants are more efficient than smaller ones.

<p>Due to the scarcity of wireless resources, efficient resource allocation is essential to the success of cellular systems. With the proliferation of bandwidth-hungry multimedia applications with diverse traffic characteristics and quality of service requirements, the resource management is becoming particularly challenging. In this thesis, we address some of the key link-layer resource allocation mechanisms that affect the performance of video streaming in cellular systems: bit-rate allocation, opportunistic scheduling, and statistical multiplexing. The bit-rate allocation problem involves the distortion-optimal assignment of source, channel, and pilot data rates under link capacity constraints. We derive an analytical model that captures the video distortion as a function of these data rates and, based on it, we study various bit-rate allocation strategies. The opportunistic scheduling problem addresses the throughput-optimal assignment of time-slots among users with diverse channel conditions under certain fairness constraints. We focus on two aspects of the opportunistic scheduling: the performance of delay-constrained streaming applications and possible extensions of the opportunistic concepts to multicast scenarios. Finally, the statistical multiplexing is a resource-efficient method for smoothing out the extreme burstiness of video streams. We study possible statistical multiplexing gains of H.264 video streams in the context of E-MBMS architecture.</p>

[pt] Este trabalho aborda o problema da alocação dos canais de tráfego em sistemas móveis celulares. A utilização de métodos de alocação mais eficientes constitui uma das principais alternativas para a melhoria do desempenho de sistemas congestionados. Além disto, a constante redução do tamanho das células exige a aplicação de métodos mais flexíveis no que diz respeito ao pré-planejamento das freqüências. Alguns dos inúmeros métodos já propostos são apresentados, e dois deles - CBWL e Segregação de Canais - são simulados em um sistema FDMA micro-celular-uni- dimensional. É feita uma comparação do desempenho oferecido por estes dois métodos, e os resultados obtidos indicam a necessidade da utilização de alguma estratégia de prioridade para o atendimento das solicitações de handoff. / [en] In this work the problem of traffic channel assignment in móbile cellular systems is adressed. The use of more efficient assignment methods represents one of the main alternatives to enhance the performance of congested systems. Moreover, the ceaseless reduction of cell sizes requires the adoption of more flexible methods already proposed are presented, and two of them - CBWL and Channel Segregation - are simulated in FDMA 1-dimensional microcellular system. The performance offered by these two methods is compared, and the results indicate the need of using some priority strategy for attending handoff requests.

[pt] Este estudo tem por objetivo contribuir para emprego de antenas adaptativas em sistemas de comunicação sem fio. É feita uma revisão dos métodos de estimação de ângulo de chegada e de sua utilização na formação de feixe. O desempenho de alguns métodos baseados em subspace fitting é comparado através de simulação considerando quatro cenários. O primeiro supões apenas a presença de ruído. Os demais consideram os modelos típicos de espalhamento local, ou seja, espalhamento aleatório dos ângulos de chegada. / [en] This work intends to contribute for the employment of the Adaptive Antennas in Wireless Communications. In this way, a review of methods for direction of arrival estimation and beamforming is presented. The performance of some subspace fitting direction of arrival estimation methods is evaluated by simulation considering four propagation scenarios: The first assumes only additive white Gaussian noise; The three others consider typical models for local scattering, which means a random angular spread of angle of arrival.

No description available.

Due to the scarcity of wireless resources, efficient resource allocation is essential to the success of cellular systems. With the proliferation of bandwidth-hungry multimedia applications with diverse traffic characteristics and quality of service requirements, the resource management is becoming particularly challenging. In this thesis, we address some of the key link-layer resource allocation mechanisms that affect the performance of video streaming in cellular systems: bit-rate allocation, opportunistic scheduling, and statistical multiplexing. The bit-rate allocation problem involves the distortion-optimal assignment of source, channel, and pilot data rates under link capacity constraints. We derive an analytical model that captures the video distortion as a function of these data rates and, based on it, we study various bit-rate allocation strategies. The opportunistic scheduling problem addresses the throughput-optimal assignment of time-slots among users with diverse channel conditions under certain fairness constraints. We focus on two aspects of the opportunistic scheduling: the performance of delay-constrained streaming applications and possible extensions of the opportunistic concepts to multicast scenarios. Finally, the statistical multiplexing is a resource-efficient method for smoothing out the extreme burstiness of video streams. We study possible statistical multiplexing gains of H.264 video streams in the context of E-MBMS architecture. / QC 20101126

Indoor parasitic cellular systems are in-building stand alone cellular networks that use the concept of simultaneously reusing the frequencies of cellular systems outside the building for wireless communications inside the building. The objective of this thesis is to provide an analysis to determine the frequency reuse possible between in-building and outside cellular systems. The amount of frequency reuse currently available for an urban office building is presented based on field strength measurements made inside the building. In addition, this thesis describes the simulation code written which models a growing cellular system for the purpose of analyzing the effect that a growing cellular system will have on in-building frequency reuse. Future in-building frequency reuse is predicted in three month intervals for a time period of six years based on the results of the simulation code. / Master of Science

[pt] A partir da necessidade do transporte de informação multimídia, foram desenvolvidos os Sistemas Celulares de Terceira Geração, ainda em fase de padronização, cujo candidato mais promissor é o UMTS (Universal Mobile Telecommunications System). De forma consonante com a tendência mundial de utilização crescente da tecnologia IP (Internet Protocol) nas redes fixas, o UMTS veio a incorporar este protocolo, que apresenta uma maior flexibilidade para a introdução de novos serviços. Assim, na arquitetura do UMTS existem atualmente dois modos de transmissão, a Comutação de Circuitos e a Comutação de Pacotes. Esta Tese de Doutorado descreve, inicialmente, os processos de estabelecimento de chamadas de voz no UMTS, tanto na modalidade de Comutação de Circuitos como na de Comutação de Pacotes. Em seguida, procura fazer uma avaliação comparativa da eficiência na execução de chamadas de voz nestas duas modalidades, com ênfase de aplicação no sentido uplink de transmissão. Neste processo, são desenvolvidas várias formas de otimização de desempenho da transmissão na interface aérea do UMTS, em particular na Comutação de Pacotes, visando tornar este modo de transmissão competitivo com o modo de Comutação de Circuitos em termos de eficiência na transmissão de voz. Embora o tratamento aqui apresentado se refira ao UMTS-FDD (UMTS Frequency Division Duplex), as técnicas aqui desenvolvidas também encontram aplicação em outros Sistemas Celulares de Terceira Geração congêneres, tal como o CDMA 2000. / [en] With the advent of multimedia traffic, Third Generation mobile systems were introduced, with the UMTS as the most promissor candidate. In consonance with the global trend of utilization of the IP technology in fixed networks, the UMTS developers decided to incorporate this protocol, which presents more facilities for the introduction of new services. Therefore, the UMTS architecture has two transmission modes: Circuit Switching and Packet Switching Modes. This Doctoral Dissertation initially describes the call setup processes (call flows) for those transmission modes. It follows a comparative evaluation of the efficiency aspect related to calls executed in both modes, considering the case of uplink transmission. In this process, several optimization techniques are introduced, aiming at the improvement of energy consumption in the air interface. The final objetive is to turn the Packet Switching Mode competitive with the Circuit Switching Mode, relative to the energy consumed for the transmission of voice calls. Though the treatment here presented refers to the UMTS-FDD technology, all the results are equally applicable to other similar systems, like the CDMA- 2000.

[pt] Este trabalho apresenta um estudo detalhado de técnicas de planejamento de sistemas celulares de terceira geração WCDMA. Primeiramente é realizado um estudo teórico do sistema WCDMA, da estrutura da interface aérea, dos diversos tipos de canais presentes no downlink e no uplink. A seguir são aprentadas técnicas de planejamento de rede, com uma análise detalhada do cálculo de enlace e do planejamento de cobertura do sistema celular. Com base neste estudo foram realizadas diversas simulações com o software aberto NPSW para diferentes situações em relação a tipos de serviço, condições de uso e carga no sistema. Estas simulações permitiram caracterizar os efeitos dos diversos parâmetros de entrada no desempenho do sistema. Finalmente, é apresentado um estudo de caso de planejamento para a região do centro do Rio de Janeiro. / [en] This work presents a detailed study of planning tecniques for third generation WCDMA cellular systems. At first a theoretical study of the WCDMA system is presented, including the structure of the air interface and the various channel types in the downlink and uplink. Following, network planning techniques are presented, with a detailed analysis of the link budget calculations and the system coverage planning issues. Based on this study, the system behaviour was simulated using the open software NPSW for different configurations of service, operation condition and system load. The simulations allowed the characterization of the effect of several parameters on the system performance. Finally, a case study of coverage planning for downtown Rio de Janeiro is presented.

- / -