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Meza W.D.T.,Center for Telecommunications Studies | Siqueira G.L.,Center for Telecommunications Studies | Matos L.J.,Graduate Program in Electrical and Telecommunications Engineering
Journal of Microwaves, Optoelectronics and Electromagnetic Applications | Year: 2014

Based on signal measurements carried out in the 5.8 GHz band, which is reserved for unlicensed WiMAX in Brazil, this paper evaluates narrowband and wideband characteristics on the suburban area of Tanguá city in Rio de Janeiro State. Fading statistics, coverage and adjusted prediction model such as Hata-COST 231, SUI and UFPA were used in order to find the model that best fits the measurement data before ultimately determining that the UFPA model proved to be the best one. Temporal dispersion is studied through the delay spread and coherence band calculated from the power delay profiles obtained in the sounded channel. © 2014 SBMO/SBMag. Source


Meza W.D.T.,Center for Telecommunications Studies | Siqueira G.L.,Center for Telecommunications Studies | Santos M.A.G.,Graduate Program in Telecommunications Engineering | Matos L.J.,Graduate Program in Telecommunications Engineering
SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings | Year: 2013

From signal measurements carried out in the 5.8 GHz band, that is reserved to unlicensed WiMAX in Brazil, this paper evaluates the signal coverage on this band in the suburban area of Tanguá. Prediction models as Hata-COST 231, SUI and UFPA (Modified SUI) were used in order to find the model that best fitted to the measurements data and then, the modified SUI model showed to be the better one. © 2013 IEEE. Source


Thomas D.H.,Center for Telecommunications Studies | De Faria G.V.,Center for Telecommunications Studies | Von Der Weid J.P.,Center for Telecommunications Studies
Microwave and Optical Technology Letters | Year: 2010

We present a simple and robust full-duplex radio-overfiber (ROF) system using two laser sources with efficient laser frequency stability control enlarging the reliability of the whole system with automatic operation. Error-free operation was obtained at 52 and 155 Mb/s. The system was successfully tested for ASI/SDI-coded digital TV transmission at 270 Mb/s. Copyright © 2010 Wiley Periodicals, Inc. Source


Cal-Braz J.,Center for Telecommunications Studies | Medina C.A.,Center for Telecommunications Studies | Sampaio-Neto R.,Center for Telecommunications Studies
Proceedings of the International Symposium on Wireless Communication Systems | Year: 2013

This paper presents a new detection scheme for the generalized spatial modulation (GeSM) MIMO system. The strategy, that takes into account the antenna combination mapping table, performs an optimal partitioning of the vector to be detected prior to the application of the maximum-likelihood detector to the established groups. The solution, focused on the case of GeSM systems with four transmit and two active antennas presents very promising results, combining good performance and ultra low complexity for scenarios with fixed wireless channel. Differing from other existing schemes, the complexity of the proposed detector shows little sensitivity to the increase of the number of receive antennas, situation when the receiver exhibits superior performance. © VDE Verlag GMBH. Source


Silva F.S.,Graduate Program in Telecommunications Engineering | Matos L.J.,Graduate Program in Telecommunications Engineering | Peres F.A.C.,Center for Telecommunications Studies | Siqueira G.L.,Center for Telecommunications Studies
SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings | Year: 2013

Broadcast television is one of the most important telecommunications systems in Brazil. Such relevance in the socio-cultural context requires a continuous pursuit of technical excellence in order to offer an increasingly attractive product to the viewer. Therefore, it is mandatory to care about the coverage and quality of the TV signal, especially when it comes to Digital TV. In this scenario, it is imperative to study propagation models to predict the coverage allowing broadcasters to properly project their stations and regulators to distribute the channels harmoniously. The aim of this study is to compare the field strength measurements of a Digital TV signal in five cities of Brazil, with the values predicted by some models and to conclude for the best one. © 2013 IEEE. Source

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