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Authors
Abstract(s)
Atualmente, grande parte das comunicações marítimas junto à costa baseiam-se em sistemas de banda estreita VHF, devido à sua facilidade de utilização e baixo custo. No entanto, os serviços de dados (banda larga) são geralmente feitos através de comunicações satélite, as quais requerem elevados custos financeiros. Torna-se necessário uma alternativa a estas comunicações que mantenha as suas capacidades operacionais mas economicamente mais baratas. Todavia, o maior problema para este tipo de implementação reside na gestão e escassez do espetro, que atualmente segue uma política de alocação estática, impossibilitando a implementação de novos serviços. Como tal, tem sido proposta a utilização de rádios cognitivos que, para além de permitir um acesso dinâmico ao espetro, são também capazes de coexistir com sistemas não cognitivos. O presente trabalho tem como objetivo o estudo das oportunidades para utilização dinâmica do espetro na banda de VHF do serviço móvel marítimo. Assim, é realizada a
monitorização destes canais em diferentes regiões do porto de Lisboa, avaliando as oportunidades de transmissão VHF. Com base nas regressões lineares, é elaborado um modelo matemático para estimar a percentagem de ocupação dos referidos canais, e avaliar o potencial uso do espetro em futuras aplicações de rádios cognitivos, nomeadamente para serviços de banda larga.
Currently, much of maritime communications along the coast are based on narrow band VHF systems due to its ease of use and low cost. Note that, data services through satellite communications systems (broadband) require high cost. An alternative to these communications, within the VHF range, maintaining its operational capabilities and being less expensive would be very useful. However, the main problem for this type of implementation lies in the management and scarcity of spectrum, which currently follows a static allocation policy, preventing the implementation of new services. So, it was recently proposed the use of cognitive radios which can dynamically access to static spectra. The present work deals with the study of the maritime mobile service occupation for dynamic spectrum access. In first place it was performed a monitoring of these channels in different locations of the port of Lisbon, evaluating the VHF transmission opportunities. In second place, based on the obtained data, a simple mathematical model to estimate the occupancy of these channels was developed. The results obtained can be useful to evaluate the potential use of the VHF spectrum in future applications of cognitive radios as well as broadband services.
Currently, much of maritime communications along the coast are based on narrow band VHF systems due to its ease of use and low cost. Note that, data services through satellite communications systems (broadband) require high cost. An alternative to these communications, within the VHF range, maintaining its operational capabilities and being less expensive would be very useful. However, the main problem for this type of implementation lies in the management and scarcity of spectrum, which currently follows a static allocation policy, preventing the implementation of new services. So, it was recently proposed the use of cognitive radios which can dynamically access to static spectra. The present work deals with the study of the maritime mobile service occupation for dynamic spectrum access. In first place it was performed a monitoring of these channels in different locations of the port of Lisbon, evaluating the VHF transmission opportunities. In second place, based on the obtained data, a simple mathematical model to estimate the occupancy of these channels was developed. The results obtained can be useful to evaluate the potential use of the VHF spectrum in future applications of cognitive radios as well as broadband services.
Description
Keywords
Rádios Cognitivos, Gestão do Espetro, Rádio Definido por Software, Regressão Linear Múltipla