Título:	Comunicações IMT-2020 : interferência e compartilhamento de frequência em ondas milimétricas
Autor(es):	Queiroz, Calil Bento
Orientador(es):	Carvalho, Paulo Henrique Portela de
Assunto:	Interferência eletromagnética Sistemas de comunicação sem fio Serviço de satélite fixo Ondas milimétricas
Data de publicação:	11-Dez-2019
Data de defesa:	27-Mai-2019
Referência:	QUEIROZ, Calil Bento. Comunicações IMT-2020: interferência e compartilhamento de frequência em ondas milimétricas. 2019. ix, 94 f., il. Dissertação (Mestrado em Engenharia Elétrica)—Universidade de Brasília, Brasília, 2019.
Abstract:	Projections estimate that global mobile data traffic may reach 57 exabytes by 2020, followed by a exponential growth in subsequent years. More than that, the number and density of mobile network users may also increase significantly, once smartphones and wireless devices are becoming more and more popular. Since fourth generation mobile communications systems are not equipped to deal with this demand, the International Telecommunications Union has standardized IMT- 2020 (International Mobile Telecommunications 2020) as the set of fifth generation technologies for mobile communications networks beyond 2020. IMT-2020 will also operate in frequency bands beyond 20 GHz, known as millimeter-wave bands. From the bands being studied as possible allocations for IMT-2020, the 27-27.5 GHz and the 37-42.5 GHz bands are identified to the fixed-satellite service, for example, and the 42.5-43.5 GHz band is identified to the radio-astronomy service. Any identification of these bands for IMT- 2020 needs to take place upon the realization of frequency sharing studies that show that the new service will not cause harmful interference to existing services. Such studies are even more relevant in 2019, when the World Radio Conference will happen. In it, the International Telecommunications Union will host debates and discussions with the goal or revising and reviewing the radio regulations for the incoming years. Because of that, the event’s agenda already includes debates around the frequency allocations for IMT-2020, based on sharing studies submitted by member states and guests. In order to contribute actively with the studies, the Brazilian National Telecommunications Agency has been developing, together with partners from academia and industry, the SHARC simulator, for sharing and compatibility analysis. One of the technologies that might be a part of IMT-2020 is Full Duplex, by which stations can transmit and receive data at the same time in the same frequency band. This technology was considered infeasible for a long time, due to the self-interference that the full duplex station’s transmission causes to the signal it receives. Recent advances in electronics, however, have made available self-interference cancellation techniques that allow the implementation of an operational full duplex node. Another challenge introduced by full duplex is the higher systemic interference it introduces, either to the cellular network or to systems operating on its frequency band. Since it is probable that IMT-2020 will share spectrum with other services, this extra interference introduced by full duplex might be harmful to other systems. Thus, this work presents frequency sharing studies between IMT-2020 and the systems cited above. These studies were performed with the FD-SHARC simulation tool, a fork of the SHARC simulator for analysis of full duplex technologies. The simulation methodology is described, followed by a feasibility analysis of full duplex technologies, so to define the scenarios in which this technology is more probable to be implemented. After that, sharing studies are presented and the interference levels estimated in the simulations are evaluated against the protection criteria of the interfered-with systems. The study concludes that IMT-2020 can indeed share the frequency bands mentioned, as long as some restrictions are imposed. Separation distances between the IMT networks and the earth stations of the fixed-satellite service and radio-astronomy stations must be established. Besides, when operating indoors, IMT-2020 can use the same frequency as the fixed-satellite service user terminal, as long as some simple coordination measures are employed. Finally, the space station of the fixed-satellite system is protected from interference in all the simulated cases. Many of the results presented here were submitted to the International Telecommunications Union and are part of the preparatory texts for the World Radio Conference. Together with hundreds of other studies, they will be used as basis for the creation of regulations of worldwide scope and will help regulatory agencies around the world take technical and country-specific decisions. Furthermore, in the best knowledge of the author, sharing studies between IMT-2020 operating in full duplex and other systems are not present in the literature. In that sense, this work presents novel contributions that deepen the discussion about the feasibility of this technology.
Unidade Acadêmica:	Faculdade de Tecnologia (FT) Departamento de Engenharia Elétrica (FT ENE)
Informações adicionais:	Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2019.
Programa de pós-graduação:	Programa de Pós-Graduação em Engenharia Elétrica
Licença:	A concessão da licença deste item refere-se ao termo de autorização impresso assinado pelo autor com as seguintes condições: Na qualidade de titular dos direitos de autor da publicação, autorizo a Universidade de Brasília e o IBICT a disponibilizar por meio dos sites www.bce.unb.br, www.ibict.br, http://hercules.vtls.com/cgi-bin/ndltd/chameleon?lng=pt&skin=ndltd sem ressarcimento dos direitos autorais, de acordo com a Lei nº 9610/98, o texto integral da obra disponibilizada, conforme permissões assinaladas, para fins de leitura, impressão e/ou download, a título de divulgação da produção científica brasileira, a partir desta data.
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