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- Implementation of a communication protocol between a geo-location database and TV white space devicesPublication . Dionísio, Rogério Pais; Ribeiro, Jorge Miguel Afonso; Paulo, MarquesTelevision White Spaces (TVWS) are a spectral opportunity, for secondary users of the spectrum to deliver broadband access to rural areas. Most of the approaches now under test worldwide use a geo-location database to inform secondary users of the available channels, and avoid interference with primary users of the spectrum. The secondary network should follow a approach capable to communicate with a geo-location spectrum database, to store and retrieve information on spectrum occupancy, location of DVB-T broadcast towers and wireless microphones, maximum EIRP of secondary White Space devices (WSDs), sensing activity and other technical parameters. One group from the Internet Engineering Task Force (IETF) is presently working on the definition of a protocol to access white spaces databases – PAWS. The IETF draft protocol was chosen and considered flexible enough to be adapted for the CREW-TV project model and requirements, since it is more comprehensive and less specific on details than other proposals.
- Cross-platform demonstrator combining spectrum sensing and a geo-location databasePublication . Dionísio, Rogério Pais; Ribeiro, José Carlos; Ribeiro, Jorge Miguel Afonso; Marques, Paulo; Rodriguez, JonathanAfter the digital switchover, a secondary access of the so-called TV White Spaces should not interfere with primary users, such as DVB-T systems and local wireless microphone devices. One consensual method for secondary spectrum users to avoid interference is to combine geo-location database with spectrum sensing. This paper describes an experimental platform that combines wireless microphone sensors with a web-based geo-location database access. Software defined radios and Internet technologies are the enabling tools in use. From test trials in a real scenario, the platform was capable to update a list of vacant channel from the geo-location database, using reliable information from blind sensing algorithms.
- TV white spaces with geo-location database access: practical considerations and trials in EuropePublication . Dionísio, Rogério Pais; Ribeiro, José Carlos; Ribeiro, Jorge Miguel Afonso; Marques, Paulo; Rodriguez, JonathanThis chapter describes outdoor transmission tests and field measurements in TV white spaces (TVWS) carried out in Europe. TVWS Measurements in Germany showed that the extended Hata model is appropriate to describe the path loss over distances up to a few kilometers. During the TVWS trial in Slovenia, we combine infrastructure sensing with geo-location database access to protect not only DVB-T, but also wireless microphone (WM) signals from TVWS devices interference.