Inaki Berenguer

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—Recently it has been shown that it is possible to improve the performance of multiple-input multiple-output (MIMO) systems by employing a larger number of antennas than actually used and selecting the optimal subset based on the channel state information. Existing antenna selection algorithms assume perfect channel knowledge and optimize criteria such as(More)
—A method to improve the performance of multiple -input–multiple-output systems is to employ a large number of antennas and select the optimal subset depending on the specific channel realization. A simple antenna-selection criterion is to choose the antenna subset that maximizes the mutual information. However, when the receiver has finite complexity(More)
— Orthogonal Frequency Division Multiplexing (OFDM) significantly reduces receiver complexity in wireless broadband systems and therefore has recently been proposed for use in wireless broadband multi-antenna (MIMO) systems. The performance of maximum likelihood detector in MIMO-OFDM system is optimal, however, its complexity , especially with higher order(More)
Cooperative diversity systems have been recently proposed as a solution to provide spatial diversity for terminals where multiple antennas are not feasible to be implemented. As in MIMO systems, space-time codes can be used to efficiently exploit the increase in capacity provided in cooperative diversity systems. In this paper we propose a two-layer linear(More)
In this paper we propose a systematic procedure for designing minimum-error-rate lattice (space-time) codes. By employing stochastic optimization techniques we design lattice (space-time) codes with minimum error rate when maximum likelihood (ML) detection is employed. Our design methodology can be tailored to optimize lattice (space-time) codes for any(More)
— In this paper, we consider multiple input multiple output-orthogonal frequency division multiplexing-code division multiplexing (MIMO-OFDM-CDM) techniques to efficiently improve the link reliability/spectral efficiency of very high data rate communication systems. In particular, we apply MIMO detection methods based on lattice reduction , partial decision(More)
— This paper develops a framework for the efficient maximum-likelihood decoding of lattice codes. Specifically we apply it to the spherical Lattice Space-Time (LAST) codes recently put forward by El Gamal et al. that have been proven to achieve the optimal diversity-multiplexing tradeoff of MIMO channels. Our solution addresses the so-called boundary(More)
—In this paper, we propose a systematic procedure for designing spherical lattice (space–time) codes. By employing sto-chastic optimization techniques we design lattice codes which are well matched to the fading statistics as well as to the decoder used at the receiver. The decoders we consider here include the optimal albeit of highest decoding complexity(More)