Browsing by Author "Ferreira, Jaime"
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- Classificação de aplicações e cenários de operação em UMTS melhoradoPublication . Franco, Cátia; Rei, Ricardo; Velez, Fernando J.; Ferreira, JaimeTerceira geração (3G) é o termo genérico utilizado para a geração de sistemas móveis de telecomunicações imediatamente posterior ao GSM. Os sistemas 3G procuram garantir melhores serviços para a transmissão de voz, textos e dados. O Sistema Universal de Telecomunicações Móveis (UMTS Universal Mobile Telecommunications System) é parte do sistema global de comunicações de terceira geração da União Internacional de Telecomunicações (ITU). A 3G foi baseada na norma GSM actual, porém evoluída, estendida e melhorada de forma a incluir novas especificações para a interface ar mais adequada para os serviços de alta velocidade e multimédia. Este sistema permite que os utilizadores da segunda geração, GSM, migrem facilmente para os serviços de terceira geração. O UMTS padrão pertence à terceira geração de redes móveis. O objectivo primordial da 3G é a realização de uma estrutura universal capaz de suportar tanto os serviços existentes como os futuros. A 3G está normalizada pelas sociedades 3G Partnership Projects: 3GPP (na Europa) e 3GPP2 (nos EUA). Os conceitos tecnológicos para os sistemas 3G continuam em desenvolvimento e proporcionaram já a definição da geração 3.5, em que se inclui o UMTS Melhorado (E-UMTS), uma rede totalmente IP (All-IP) que pretende assegurar maior capacidade, flexibilidade na rede nuclear de suporte (core network) e utilização de serviços integrados suplementares. Dada a complexidade das redes UMTS e E-UMTS, nem sempre é possível desenvolver modelos analíticos simples para projectar e planear o sistema. Para ultrapassar essas dificuldades recorre-se frequentemente a simulações, que se baseiam num desenho topológico existente ou planeado, numa estimativa da distribuição do tráfego e numa variedade de serviços com múltiplos requisitos de qualidade de serviço (QoS), o que constitui uma grande diferença relativamente às redes de segunda geração.
- Deployment scenarios and applications characterisation for enhanced UMTS simulationPublication . Ferreira, Jaime; Velez, Fernando JoséAn overview of E-UMTS deployment scenarios and supported services is presented, based on the views of currently relevant players. Deployment and mobility scenarios include expected population density, and usage of service mix, for each environment. Nearly thirty applications are considered. However, a reduced set of applications is needed for simulations purposes, and scenarios were defined with a selection of the most relevant applications. E-UMTS traffic generation and activity models, based on population and service penetration values, are also described and characterised. ON/OFF states have been characterised by appropriate statistical distributions and parameters.
- E-UMTS Services and Applications CharacterisationPublication . Ferreira, Jaime; Velez, Fernando JoséDifferent points of view are compared for the classification of Enhanced UMTS (E-UMTS) mixture of applications, namely ITU-T I.211, UMTS Forum and 3GPP ones. A set of characterisation parameters (e.g., data rate, tolerance to delay and error, and session duration) is described, and a first assignment of parameter values for these services is proposed. An overview of E-UMTS deployment scenarios and supported services is then presented, based on the views of nowadays-relevant players. The influence of mobility in E-UMTS is discussed, and mobility models and scenarios are given. Deployment and mobility scenarios include expected population density, mobility characteristics, and usage of service mix, for each environment. A number of nearly thirty applications are considered. However, a reduced set of applications is needed for simulations purposes, and scenarios were defined with a selection of the most relevant applications. Finally, E-UMTS traffic generation and activity models, based on population and service penetration values, were described and characterised. ON/OFF states were characterised by appropriate statistical distributions and parameters.
- Enhanced UMTS Deployment and Mobility ScenariosPublication . Ferreira, Jaime; Gomes, Álvaro; Velez, Fernando JoséAn overview of Enhanced UMTS (E-UMTS) deployment scenarios and supported services is presented, based on the views of nowadays-relevant players. The influence of mobility in E-UMTS is discussed and a set of mobility models is given. Then, a set of scenarios is described, that put together the most important components of E-UMTS deployment situations. These include expected population density, mobility characteristics, and expected usage of service mix, for each environment. A number of nearly thirty applications, divided into in five groups (Sound, High Interactive Multimedia, Narrowband, Wideband, Broadband), is considered.
- Enhanced UMTS services and applications characterisationPublication . Ferreira, Jaime; Velez, Fernando J.Different points of view are compared for the classification of Enhanced UMTS (E-UMTS) applications, namely ITU-T I.211, UMTS Forum and 3GPP ones. A set of characterisation parameters (e.g. data rate, tolerance to delay and error, and session duration) is described, and a first assignment of parameter values for these services is proposed. An overview of E-UMTS deployment scenarios and supported services is then presented, based on the views of nowadays-relevant players. The influence of mobility in E-UMTS is discussed, and mobility models and scenarios are given. Deployment and mobility scenarios include expected population density, mobility characteristics, and usage of service mix, for each environment. A total of nearly thirty applications are considered. However, a reduced set of applications is needed for simulations purposes, and scenarios were defined with a selection of the most relevant applications. Finally, E-UMTS traffic generation and activity models, based on population and service penetration values, are described and characterised. ON/OFF states have been characterised by appropriate statistical distributions and parameters.
- Source Traffic Modelling for Enhanced UMTS SimulationPublication . Ferreira, Jaime; Velez, Fernando JoséEnhanced UMTS traffic generation and activity models are described and characterised, based on population and service penetration values. As a reduced set of scenarios is needed for simulation purposes, scenarios were defined with a selection of the most relevant applications. ON/OFF states have been characterised by appropriate statistical distributions for long-range dependence, and parameters for source traffic modelling have been presented.