Distance distribution for turbo-equalized systems over static frequency selective channels
ABSTRACT In this paper we investigate the Euclidean distance distribution in turbo-equalized systems over static frequency-selective (ISI) channels . We propose a novel approach in evaluating the squared Euclidean distance between transmitted sequences at the output of the ISI channel based on the correlogram of error sequences. By inspecting autocorrelation properties of error sequences, we derive the main statistics of the output Euclidean distance. The proposed method provides a more comprehensive tool to predict system behavior with finite or infinite packet length. We exploit obtained results to evaluate the frame error rate (FER) performance of the system under maximum-likelihood sequence estimation.
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ABSTRACT: The performance of maximum-likelihood decoding of a serial concatenation comprising a high-rate block code, convolutional code, or a turbo code, a uniform interleaver, and a partial response channel with additive white Gaussian noise is addressed. The effect of a channel precoder on the system performance is also considered. Bit- and word-error rate estimates based upon properties of the average Euclidean distance spectrum of the coded partial response channel are derived. The estimates are compared to computer simulation results, and implications for system design are discussedIEEE Transactions on Communications 04/2001; · 1.75 Impact Factor
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ABSTRACT: This paper presents a receiving scheme intended to combat the detrimental effects of intersymbol interference for digital transmissions protected by convolutional codes. The receiver performs two successive soft-output decisions, achieved by a symbol detector and a channel decoder, through an iterative process. At each iteration, extrinsic information is extracted from the detection and decoding steps and is then used at the next iteration as in turbo-decoding. From the implementation point of view, the receiver can be structured in a modular way and its performance, in bit error rate terms, is directly related to the number of modules used. Simulation results are presented for transmissions on Gauss and Rayleigh channels. The results obtained show that turbo-equalization manages to overcome multipath effects, totally on Gauss channels, and partially but still satisfactorily on Rayleigh channels.European Transactions on Telecommunications 08/1995; 6(5):507 - 511. · 1.05 Impact Factor
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ABSTRACT: In this paper, we consider a coded transmission over a frequency-selective channel. We propose to study analytically the convergence of the turbo-detector using a maximum a posteriori (MAP) equalizer and a MAP decoder. We show that the densities of the extrinsic log likelihood ratios (LLRs) exchanged during the iterations are e-symmetric and output-symmetric. Under the Gaussian approximation, this property allows to perform a one-dimensional (1-D) analysis of the turbo-detector. By deriving the analytical expressions of the extrinsic LLR distributions under the Gaussian approximation, we prove that the bit error rate (BER) performance of the turbo-detector converges to the BER performance of the coded additive white Gaussian noise (AWGN) channel at high signal to noise ratio (SNR), for any frequency-selective channel.IEEE Transactions on Signal Processing 05/2008; · 2.81 Impact Factor