Aplicações de antenas adaptativas em sistemas de comunicações móveis / Applications of adaptive antennas in wireless communications systems

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The increasing demand for wireless communications services has demanded the development of technologies that allow serving a bigger amount of users without increasing the bandwidth used today. It also has an increasing demand for services that need high transmission rates on mobile terminal, as Internet and video transfer. On the other hand, the user desires high quality in the service, which implies in low symbol error rate (SER). For this, different techniques can be used, e.g. smart antennas and MIMO. This work proposes to present a study of some smart antennas and MIMO applications in wireless communications systems. To reach this objective, primarily a study of linear, circular and rectangular antenna array is realized. After that, some methods for beamforming are analyzed. These methods are used to calculate the weight of each element of the array to achieve a specified radiation pattern. Comparative studies of these methods are realized with computational simulations. The direction of arrival (DOA) estimation problem is analyzed with the use of computational simulations, where the systems parameters are modified. These studies allow finding the method with better performance in the DOA estimation. The MIMO systems concept was introduced with the aim to show how to improve the SER in a Rayleigh channel. With this technology, multiplexing and diversity gains are gotten. The discussion is finished with a set of simulations showing the improvement in SER when MIMO are used. Finally, it is shown how smart antennas and MIMO can be applied in wireless communications systems. The results show that, independently of the communication system considered, it has a significant increase in communication quality.

ASSUNTO(S)

antenas inteligentes sistemas de comunicações móveis conjuntos de antenas telecomunicacoes mimo

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