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In order to take advantage of adaptive transmission techniques or multiple antennas, it is necessary to have actual channel state information (CSI) at transmitter and/or receiver. Due to system constraints and the time varying nature of the mobile radio channel, the CSI might be outdated, leading to performance degradation of the system. Channel prediction can provide up-to-date channel state information...
In this paper, the energy detection spectrum sensing technique, based on the wavelet transform, is investigated. In order to evaluate the accuracy of the methodology, spectrum measurements were made in bands allocated for FM broadcast (88-108 MHz) and mobile services (824-835 MHz). Modifications in an existing technique were proposed in order to improve the spectrum sensing when applied in real environments.
This work proposes a hybrid traffic model for multimedia networks as a fundamental element in a network planning optimization procedure. The proposed model uses a combination of the fBm (fractional Brownian motion) and Markovian traffic characterization procedures combined with link parameters in order to produce more accurate values of QoS metrics. The hybrid traffic model was evaluated in a network...
This paper presents a set of software tools focused on the characterization of the propagation environment to aid in the design of public safety communication systems. Several measurement campaigns were made to extract the statistical behavior of the narrowband fading over a mobile environment on the UHF band in the city of Brasilia. A sampling method is defined making possible the analysis for long...
This paper presents a hybrid evolutionary algorithm to synthesize the resonator filters of an arbitrary topology. In this approach the structure space is explored concerning predefined small building-blocks having specific functionalities (resonator or coupling) and rules for structural restrictions. The method used 2D representation, proposing new strong genetic operators and combining a biobjective...
In this paper we present the development and validation of an experimental platform based in open source software and the development of a package for monitoring purposes. The software package with its components is described and validated through a group of tests and examples. These results are the initial support for future research which includes new ideas in the NGN (next generation networks)...
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