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Previous issue date: 2015-08-21 / A crescente demanda por tr?fego de dados em redes de acesso de banda larga sem fio ? Internet requer tanto o desenvolvimento de novas tecnologias de acesso mais eficientes quanto que novas faixas de frequ?ncia do espectro eletromagn?tico sejam alocadas para este fim. A introdu??o de um grande n?mero de small cells em redes celulares aliado ? ado??o de forma complementar de tecnologias de Wireless Local Area Networks (WLAN) em faixas de espectro n?o-licensiadas tem se verificado como um dos conceitos mais promissores. Uma das alternativas dentro deste conceito ? a introdu??o de small cells Long Term Evolution (LTE) operando em espectro n?o-licensiado Industrial, Science and Medical (ISM) de 5Gigahertz (GHz), numa abordagem conhecida como Unlicensed LTE (LTE-U). No entanto, a tecnologia de acesso de banda larga sem fio IEEE 802.11 (Wi-Fi) j? se encontra bastante difundida e operando nessa faixa de espectro, o que pode acarretar problemas de desempenho derivados da coexist?ncia de ambas as tecnologias na mesma faixa de espectro. Al?m disso, existe a necessidade de melhorar a opera??o do Wi-Fi para que possa suportar cen?rios com um grande n?mero de redes vizinhas, cada uma com um grande n?mero de n?s (conhecido como "?implanta??o densa"?). ? sabido que o desempenho global das redes Wi-Fi cai de forma acentuada com o aumento de n?mero de d?s compartilhando o canal, e portanto mecanismos para aumentar sua efici?ncia espectral se fazem necess?rios. Este trabalho ? dedicado ao problema da coexist?ncia entre diferentes sistemas de acesso ? banda larga sem fio operando nas mesmas faixas de espectro n?o-licensiado, e como resolver esses problemas por meio de algoritmos de coordena??o distribu?dos. O problema da coexist?ncia entre redes diferentes (i.e. LTE e Wi-Fi) e o problema de coexist?ncia entre diferentes redes da mesma tecnologia (i.e. m?ltiplas Overlapping Basic Subscriber Sets (OBSSs) Wi-Fi) ? analisado qualitativamente e quantitativamente via simula??o sist?mica, e suas principais quest?es a serem enfrentadas s?o identificadas. Com base nisso, solu??es distribu?das de coordena??o s?o propostas e avaliadas via simula??o sist?mica tanto para o problema de coexist?ncia inter-tecnologias como para o problema de coexist?ncia intra-tecnologia. Os resultados das avalia??es indicam que as solu??es concebidas prov?m ganhos significativos ante uma situa??o de coexist?ncia sem coordena??o distribu?da. / The increasing demand for Internet data traffic in wireless broadband access networks
requires both the development of efficient, novel wireless broadband access technologies
and the allocation of new spectrum bands for that purpose. The introduction of a great
number of small cells in cellular networks allied to the complimentary adoption of
Wireless Local Area Network (WLAN) technologies in unlicensed spectrum is one of
the most promising concepts to attend this demand. One alternative is the aggregation
of Industrial, Science and Medical (ISM) unlicensed spectrum to licensed bands, using
wireless networks defined by Institute of Electrical and Electronics Engineers (IEEE) and
Third Generation Partnership Project (3GPP). While IEEE 802.11 (Wi-Fi) networks are
aggregated to Long Term Evolution (LTE) small cells via LTE / WLAN Aggregation
(LWA), in proposals like Unlicensed LTE (LTE-U) and LWA the LTE air interface itself
is used for transmission on the unlicensed band. Wi-Fi technology is widespread and
operates in the same 5 GHz ISM spectrum bands as the LTE proposals, which may bring
performance decrease due to the coexistence of both technologies in the same spectrum
bands. Besides, there is the need to improve Wi-Fi operation to support scenarios with
a large number of neighbor Overlapping Basic Subscriber Set (OBSS) networks, with
a large number of Wi-Fi nodes (i.e. dense deployments). It is long known that the
overall Wi-Fi performance falls sharply with the increase of Wi-Fi nodes sharing the
channel, therefore there is the need for introducing mechanisms to increase its spectral
efficiency. This work is dedicated to the study of coexistence between different wireless
broadband access systems operating in the same unlicensed spectrum bands, and how to
solve the coexistence problems via distributed coordination mechanisms. The problem
of coexistence between different networks (i.e. LTE and Wi-Fi) and the problem of
coexistence between different networks of the same technology (i.e. multiple Wi-Fi
OBSSs) is analyzed both qualitatively and quantitatively via system-level simulations,
and the main issues to be faced are identified from these results. From that, distributed
coordination mechanisms are proposed and evaluated via system-level simulations, both
for the inter-technology coexistence problem and intra-technology coexistence problem.
Results indicate that the proposed solutions provide significant gains when compare to
the situation without distributed coordination.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21258 |
| Date | 21 August 2015 |
| Creators | Abinader J?nior, Fuad Mousse |
| Contributors | 04401565487, Silva, Jos? Patrocinio da, 67160042468, http://lattes.cnpq.br/5753289728835624, Rodrigues, Marcio Eduardo da Costa, 07460950742, http://lattes.cnpq.br/2116993138825543, Sousa J?nior, Vicente Angelo de, 26550455804, http://lattes.cnpq.br/6358312955522220, Barreto, Andr? Noll, 02436834725, http://lattes.cnpq.br/8999676470821349, Maciel, Tarcisio Ferreira, 54744598315, http://lattes.cnpq.br/2055476391340850, D'Assun??o, Adaildo Gomes |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA EL?TRICA E DE COMPUTA??O, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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