Browsing by Author "Franco, Cátia"
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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.
- Cost/Revenue Optimisation of Enhanced UMTS Cellular Planning in Urban ScenariosPublication . Franco, Cátia; Rei, Ricardo; Velez, Fernando JoséBased in a definition of simulations scenarios, traffic behaviour, and QoS (Quality of Service) aspects, a SLS (System Level Simulator) is used for obtaining system capacity results for urban scenarios, when overload conditions are considered. Optimum values of the cell coverage distance that maximise the profit by unit area were found. For prices of 5 and 7 Euro cents/MB, optimum values of 70 % and 140 %, respectively, were found for profit (for a coverage distance of ~414 m).
- Enhanced UMTS Micro-Celular Multi-Service Planning Optimisation in Business City CentresPublication . Franco, Cátia; Rei, Ricardo; Velez, Fernando JoséOptimisation of the cellular planning process for multi-service Enhanced UMTS in business city centre environments is addressed by using results for system capacity as an input for a cost/revenue function. Based in a definition of simulations scenarios, traffic behaviour, and Quality of Service aspects, a System Level Simulator is used for obtaining system capacity results in the business city centre scenario when overload conditions are considered. Optimum values of the cell coverage distance that maximise the profit per unit length were found. For prices of 5 and 7 Euro cents/MB, optimum values of 80 and 150 % occur around 240m, respectively.
- Enhanced UMTS Simulation-based Cellular Planning in Urban ScenariosPublication . Cabral, Orlando Manuel Brito; Velez, Fernando José; Franco, Cátia; Rei, RicardoAspects of cellular planning for E-UMTS (Enhanced UMTS) are addressed, and results for system capacity are obtained, as a function of the coverage distance. E-UMTS traffic generation and activity models are described and characterised, based on population and service penetration values. An urban scenario was defined with a selection of relevant multi-rate bursty applications. By using a System Level Simulator results were obtained for the end-to-end delay, and for blocking and handover failure probabilities. By using these results, models for the supported fraction of active users and throughput were obtained, as a function of the cell coverage distance. When the coverage distance decreases from 600 to ~200 m, the supported throughput per km2 increases from ~1Mb/s to ~5 Mb/s. By using trisectorial antennas with one amplifier a maximum throughput per BS of 600kb/s was obtained.
- Urban Cellular Planning Optimisation of Multi-service Enhanced UMTS Based in Economic IssuesPublication . Cabral, Orlando Manuel Brito; Velez, Fernando J.; Franco, Cátia; Rei, RicardoResults for Enhanced UMTS (E-UMTS) cost/revenue optimisation are obtained, as a function of the coverage distance, R. E-UMTS traffic generation and activity models are described and characterised in an urban scenario based on population and service penetration values. By using a System Level Simulator results were obtained for blocking and handover failure probabilities. Models for the supported fraction of active users and for the supported throughput, as a function of active users, were obtained. When one amplifier is used, the maximum throughput per BS is around 600kb/s. However, it achieves values up to 2000kb/s when three amplifiers per BS are considered. Generally, the profit in percentage is a decreasing function with R. The use of three amplifiers per BS is strongly advised in order to get cheaper communications, with prices that vary from 0.016 to 0.07 €/min, for R=250 and 1075m, respectively.