The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
F Sterle - One of the best experts on this subject based on the ideXlab platform.
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widely Linear decision feedback equalizer for time dispersive Linear mimo channels
IEEE Transactions on Signal Processing, 2005Co-Authors: Davide Mattera, Luigi Paura, F SterleAbstract:The paper deals with the transmission over multiple-input/multiple-output channels exhibiting time-dispersion. A minimum mean-square error equalizer based on widely Linear Processing combined with the decision-feedback (DF) strategy is implemented via finite-impulse-response filters. The proposed equalizer provides considerable performance gain at the expense of a limited increase in computational complexity. The performance analysis has been carried out accounting for mismatch conditions always present in practice. The results confirm the stronger sensitivity of the DF-based equalizers with respect to the feedforward-based ones when system parameters are not accurately known.
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widely Linear mmse equaliser for mimo Linear time dispersive channel
Electronics Letters, 2003Co-Authors: Davide Mattera, Luigi Paura, F SterleAbstract:Transmission over multiple-input/multiple-output (MIMO) channels, which exhibit time-dispersion since high bit-rate services must be provided, is considered. A minimum mean square error (MMSE) equaliser is proposed, based on widely Linear rather than Linear Processing implemented via finite impulse response filters.
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widely Linear mmse equalizer for mimo Linear time dispersive channel
International Symposium on Image and Signal Processing and Analysis, 2003Co-Authors: Davide Mattera, Luigi Paura, F SterleAbstract:The paper deals with transmission over multiple-input/multiple-output (MIMO) communication systems where, due to the large demand of high bit-rate telecommunication services, is required to take into account the time-dispersion of the channel. Recently, widely Linear Processing, which can be considered as a generalization of Linear Processing, has been proposed for single-input/single-output (SISO) and MIMO zero-memory equalizer. In this paper, widely Linear Processing has been extended to the general case of minimum mean square error (MMSE) equalizer for both finite impulse response (FIR) and recursive structures. Simulation results (with reference to recursive structure) show that the proposed equalizer significantly outperforms the Linear MMSE equalizer and decision feedback one in operative conditions of practical interest where the conditions of joint circularity of input and output signals are not satisfied (e.g., DS/WCDMA employing BPSK scheme).
A Lampe - One of the best experts on this subject based on the ideXlab platform.
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receivers with widely Linear Processing for frequency selective channels
IEEE Transactions on Communications, 2003Co-Authors: H Gerstacker, Robert Schober, A LampeAbstract:We propose several equalization schemes based on widely Linear Processing (WLP). The received signal and its complex conjugate are separately filtered and the results are Linearly combined. It is shown that WLP yields a gain in performance if the (noiseless) received signal can be interpreted as the convolution of a real-valued data sequence and an equivalent complex-valued intersymbol interference channel impulse response. Such a model applies to, e.g., amplitude-shift keying, offset quadrature amplitude modulation, and binary minimum-shift keying-type modulation. We consider receivers without and with decision feedback. Finite impulse response filters are derived for these structures, which are optimum with respect to the zero-forcing and minimum mean-squared error (MMSE) criteria, respectively. In the MMSE case, adaptive algorithms for filter adjustment are given. Infinite filter orders are investigated in order to obtain analytical performance results. Furthermore, suboptimum trellis-based detection with widely Linear preProcessing is briefly discussed. It is demonstrated analytically and by numerical examples that widely Linear schemes may outperform conventional schemes significantly, depending on the considered application.
Ignacio Santamaria - One of the best experts on this subject based on the ideXlab platform.
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information theoretic analysis of a family of improper discrete constellations
Entropy, 2018Co-Authors: Ignacio Santamaria, Pedro M Crespo, Christian Lameiro, Peter J SchreierAbstract:Non-circular or improper Gaussian signaling has proven beneficial in several interference-limited wireless networks. However, all implementable coding schemes are based on finite discrete constellations rather than Gaussian signals. In this paper, we propose a new family of improper constellations generated by widely Linear Processing of a square M-QAM (quadrature amplitude modulation) signal. This family of discrete constellations is parameterized by κ , the circularity coefficient and a phase ϕ . For uncoded communication systems, this phase should be optimized as ϕ * ( κ ) to maximize the minimum Euclidean distance between points of the improper constellation, therefore minimizing the bit error rate (BER). For the more relevant case of coded communications, where the coded symbols are constrained to be in this family of improper constellations using ϕ * ( κ ) , it is shown theoretically and further corroborated by simulations that, except for a shaping loss of 1.53 dB encountered at a high signal-to-noise ratio (snr), there is no rate loss with respect to the improper Gaussian capacity. In this sense, the proposed family of constellations can be viewed as the improper counterpart of the standard proper M-QAM constellations widely used in coded communication systems.
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properness and widely Linear Processing of quaternion random vectors
IEEE Transactions on Information Theory, 2010Co-Authors: Javier Via, David Ramirez, Ignacio SantamariaAbstract:In this paper, the second-order circularity of quaternion random vectors is analyzed. Unlike the case of complex vectors, there exist three different kinds of quaternion properness, which are based on the vanishing of three different complementary covariance matrices. The different kinds of properness have direct implications on the Cayley-Dickson representation of the quaternion vector, and also on several well-known multivariate statistical analysis methods. In particular, the quaternion extensions of the partial least squares (PLS), multiple Linear regression (MLR) and canonical correlation analysis (CCA) techniques are analyzed, showing that, in general, the optimal Linear Processing is full-widely Linear. However, in the case of jointly Q-proper or Cη-proper vectors, the optimal Processing reduces, respectively, to the conventional or semi-widely Linear Processing. Finally, a measure for the degree of improperness of a quaternion random vector is proposed, which is based on the Kullback-Leibler divergence between two zero-mean Gaussian distributions, one of them with the actual augmented covariance matrix, and the other with its closest proper version. This measure quantifies the entropy loss due to the improperness of the quaternion vector, and it admits an intuitive geometrical interpretation based on Kullback-Leibler projections onto sets of proper augmented covariance matrices.
Davide Mattera - One of the best experts on this subject based on the ideXlab platform.
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widely Linear decision feedback equalizer for time dispersive Linear mimo channels
IEEE Transactions on Signal Processing, 2005Co-Authors: Davide Mattera, Luigi Paura, F SterleAbstract:The paper deals with the transmission over multiple-input/multiple-output channels exhibiting time-dispersion. A minimum mean-square error equalizer based on widely Linear Processing combined with the decision-feedback (DF) strategy is implemented via finite-impulse-response filters. The proposed equalizer provides considerable performance gain at the expense of a limited increase in computational complexity. The performance analysis has been carried out accounting for mismatch conditions always present in practice. The results confirm the stronger sensitivity of the DF-based equalizers with respect to the feedforward-based ones when system parameters are not accurately known.
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widely Linear mmse equaliser for mimo Linear time dispersive channel
Electronics Letters, 2003Co-Authors: Davide Mattera, Luigi Paura, F SterleAbstract:Transmission over multiple-input/multiple-output (MIMO) channels, which exhibit time-dispersion since high bit-rate services must be provided, is considered. A minimum mean square error (MMSE) equaliser is proposed, based on widely Linear rather than Linear Processing implemented via finite impulse response filters.
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widely Linear mmse equalizer for mimo Linear time dispersive channel
International Symposium on Image and Signal Processing and Analysis, 2003Co-Authors: Davide Mattera, Luigi Paura, F SterleAbstract:The paper deals with transmission over multiple-input/multiple-output (MIMO) communication systems where, due to the large demand of high bit-rate telecommunication services, is required to take into account the time-dispersion of the channel. Recently, widely Linear Processing, which can be considered as a generalization of Linear Processing, has been proposed for single-input/single-output (SISO) and MIMO zero-memory equalizer. In this paper, widely Linear Processing has been extended to the general case of minimum mean square error (MMSE) equalizer for both finite impulse response (FIR) and recursive structures. Simulation results (with reference to recursive structure) show that the proposed equalizer significantly outperforms the Linear MMSE equalizer and decision feedback one in operative conditions of practical interest where the conditions of joint circularity of input and output signals are not satisfied (e.g., DS/WCDMA employing BPSK scheme).
Shlomo Shamai - One of the best experts on this subject based on the ideXlab platform.
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spectral efficiency of cdma with random spreading
IEEE Transactions on Information Theory, 1999Co-Authors: Sergio Verdu, Shlomo ShamaiAbstract:The CDMA channel with randomly and independently chosen spreading sequences accurately models the situation where pseudonoise sequences span many symbol periods. Furthermore, its analysis provides a comparison baseline for CDMA channels with deterministic signature waveforms spanning one symbol period. We analyze the spectral efficiency (total capacity per chip) as a function of the number of users, spreading gain, and signal-to-noise ratio, and we quantify the loss in efficiency relative to an optimally chosen set of signature sequences and relative to multiaccess with no spreading. White Gaussian background noise and equal-power synchronous users are assumed. The following receivers are analyzed: (a) optimal joint Processing, (b) single-user matched filtering, (c) decorrelation, and (d) MMSE Linear Processing.
