Renato R. Lopes

Learn More
Resumo— Diversas atividades, como a exploração e o moni-toramento de reservatórios de petróleo, requerem o conhecimento de propriedades da subsuperfície da região de interesse. A determinação destas propriedadesé o objetivo do processamento sísmico. Diversos métodos de processamento sísmico guardam grande semelhança com aqueles usados pela comunidade de(More)
— In this paper, we propose an adaptive radio interface scheme for systems that employ multiple antennas. This is in contrast to the adaptive interface of single-antenna systems like in current packet data cellular systems. We propose groups of transmission parameters called Modulation, Coding and Antenna Schemes (MCAS) that are chosen according to the(More)
—In this paper we propose low-complexity algorithms for estimating flat, time-varying and spatially correlated MIMO channels. The proposed estimators employ Kalman filters to track the channel in orthogonal space-time block coded systems. After developing a state-space model for spatially correlated MIMO channels, we show that the proposed estimators can be(More)
We derive and analyze two modified Kalman channel estimators (KCE) for time-varying, flat, spatially correlated MIMO channels in systems employing orthogonal space-time block codes: the steady-state KCE, which is less complex than the KCE, and the fading memory KCE, which is more robust to model mismatch.
In this paper, we propose a semi-blind state-space based receiver that jointly performs channel estimation and data detection in MIMO systems subject to fast frequency-selective fading. To accomplish these two tasks, we first define state equations representing the dynamics of channel and transmitted signals. Then, we obtain the state vector by(More)
Hybrid multiple-input multiple-output (MIMO) transceiver scheme (HMTS) combines transmit diversity and spatial multiplexing, thus achieving at the same time the two possible spatial gains offered by MIMO channels. In the design of HMTS spatial diversity and spatial multiplexing branches are disposed in parallel in order to achieve diversity and multiplexing(More)
Recent work has shown that, besides providing a conventional stacked section in which reflections are enhanced, the Common-Reflection-Surface (CRS) stacking method may be used to obtain a stacked section mainly composed of diffraction events. Therefore, CRS can be applied to separate reflection and diffraction events in the resulting zero-offset (ZO)(More)
— This paper introduces a turbo-fuzzy equalizer (TFEQ) to cope with the inter-symbol interference effects and impulsive noise occurrences in bandlimited digital communication channels, such as the indoor and outdoor power line circuits. We exploit a close relationship between the fuzzy and Bayesian equalizers to derive an adaptive nonsingleton turbo-fuzzy(More)