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Browsing by Author "Carvalho, Vitor"

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  • Aspects of Cellular Planning for Emergency and Safety Services in Mobile WiMax Networks
    Publication . Velez, Fernando J.; Carvalho, Vitor; Santos, Dany; Marcos, Rui P.; Costa, Rui; Sebastião, Pedro; Rodrigues, António
    This work addresses cellular planning aspects for a WiMax (worldwide interoperability for microwave access) point-to-multipoint wireless network to be developed in the region of Beira Interior. It is concentrated in more detail in the district of Covilha, and, particularly, in the urban area of the city, in order to guarantee communications from the Health Science Faculty of University of Beira Interior (HSF/UBI)/ Hospital Pero da Covilha to all central urban area of the city. By having aspects related with the carrier-to-noise and carrier-to-interference ratios into account, one concluded that it is necessary to consider a cellular structure with sectorisation, and cell coverage distances around 3 km. Because this zone is very hilly, the optimization of the choice of the location for base stations is essential; the potentialities of the GIS (geographic information systems) tools were explored to optimise the existence of line of sight coverage in coverage. Future research directions regarding architectures for interoperability and mobile IP, security, and the impact of multimedia applications are also addressed.
    2006-01Conference object Open access Show more
  • Cellular Planning of an IEEE 802.16 Wireless Metropolitan Area Network
    Publication . Velez, Fernando José; Carvalho, Vitor; Santos, Dany; Marcos, Rui P.; Costa, Rui; Sebastião, Pedro; Tomé, Ricardo; Rodrigues, António
    This work intends to develop a WiMax (Worldwide Interoperability for Microwave Access) point-to-multipoint wireless network that includes all the district of Covilhã, and particularly the urban area of the city in detail, with the objective to guarantee a point-to-multipoint connection from the Health Science Faculty of the University of Beira Interior (HSF/UBI) / Hospital Pêro da Covilhã to all urban area of the centre of the city. The cellular planning of this WiMax mobile network was done having in account aspects related with the carrier-to-noise ratio and carrier-to-interference ratio, concluding that is necessary to consider a cellular structure with coverage distances of 3 km and sectorisation is needed to create a high capacity wireless network in the urban area of Covilhã. Because this zone is very hilly, the choice of the location for base stations is essential; one used the potentialities of the GIS (Geographic Information Systems) tools to optimize the line of sight coverage and, simultaneously, reduce the propagation exponent. A new mobile IP architecture for Wi-Fi/WiMax interoperability is being conceived, developed and implemented based in Media Independent Handover.
    2006-05Conference object Open access Show more
  • Concepção e Planeamento de Redes sem Fios IEEE 802.16
    Publication . Carvalho, Vitor; Santos, Dany; Marcos, Rui; Costa, Rui; Velez, Fernando J.; Sebastião, Pedro; Rodrigues, António; Riscado, José; Romão, José; Cavaleiro, Victor
    Esta comunicação aborda aspectos de projecto e planeamento celular duma rede sem fios WiMax (IEEE 802.16) para interligar ponto-a-ponto a Faculdade de Ciências da Saúde da Universidade da Beira Interior (FCS/UBI) ao Hospital Amato Lusitana (Castelo Branco), uma rede ponto-multiponto para ligar a FCS/UBI/Hospital Pêro da Covilhã a toda a área urbana do centro da cidade da Covilhã e uma rede móvel celular dedicada aos serviços públicos de emergência e de segurança, abrangendo toda a região da Beira-Interior, fazendo-se a avaliação detalhada da existência de linha de vista no concelho da Covilhã. Efectuou-se o planeamento tendo em conta aspectos relacionados com a relação portadora-ruído, C/N, e a relação portadora-interferência, concluindo-se ser necessário usar sectorização e considerar sobreposição de micro-células à estrutura macro-celular (cell overlay). Utilizaram-se ferramentas GIS para auxiliar no processo de determinação das posições para as estações de base e da respectiva área com linha de vista, de forma a assegurar um expoente de propagação baixo. Dos resultados para a ligação ponto-a-ponto Covilhã-Gardunha-Castelo Branco, conclui-se que é possível assegurar comunicação com qualidade a 3.5 GHz, mas a 5.8 GHz, como a distância máxima para a qual C/N<(C/N)min é de 25 km, é necessário aumentar o ganho de pelo menos uma das antenas para assegurar a qualidade da ligação.
    2005-09Conference object Open access Show more