2017
Santos, Irene; Murillo-Fuentes, Juan Jose; Boloix-Tortosa, Rafael; Arias-de-Reyna, Eva; Olmos, Pablo M
Expectation Propagation as Turbo Equalizer in ISI Channels Artículo de revista
En: IEEE Transactions on Communications, vol. 65, no. 1, pp. 360–370, 2017, ISSN: 0090-6778.
Resumen | Enlaces | BibTeX | Etiquetas: BCJR, complex-valued, Expectation propagation (EP), ISI, Journal, turbo equalization
@article{Santos2017,
title = {Expectation Propagation as Turbo Equalizer in ISI Channels},
author = {Irene Santos and Juan Jose Murillo-Fuentes and Rafael Boloix-Tortosa and Eva Arias-de-Reyna and Pablo M Olmos},
url = {http://ieeexplore.ieee.org/document/7587428/},
doi = {10.1109/TCOMM.2016.2616141},
issn = {0090-6778},
year = {2017},
date = {2017-01-01},
journal = {IEEE Transactions on Communications},
volume = {65},
number = {1},
pages = {360--370},
abstract = {In probabilistic equalization of channels with inter-symbol interference, the BCJR algorithm and its approximations become intractable for high-order modulations, even for moderate channel dispersions. In this paper, we introduce a novel soft equalizer to approximate the symbol a posteriori probabilities (APP), where the expectation propagation (EP) algorithm is used to provide an accurate estimation. This new soft equalizer is presented as a block solution, denoted as block-EP (BEP), where the structure of the matrices involved is exploited to reduce the complexity order to O(LN2) , i.e., linear in the length of the channel, L , and quadratic in the frame length, N . The solution is presented in complex-valued formulation within a turbo equalization scheme. This algorithm can be cast as a linear minimum-mean-squared-error (LMMSE) turbo equalization with double feedback architecture, where constellations being discrete is a restriction exploited by the EP that provides a first refinement of the APP. In the experiments included, the BEP exhibits a robust performance, regardless of the channel response, with gains in the range 1.5\textendash5 dB compared with the LMMSE equalization.},
keywords = {BCJR, complex-valued, Expectation propagation (EP), ISI, Journal, turbo equalization},
pubstate = {published},
tppubtype = {article}
}
In probabilistic equalization of channels with inter-symbol interference, the BCJR algorithm and its approximations become intractable for high-order modulations, even for moderate channel dispersions. In this paper, we introduce a novel soft equalizer to approximate the symbol a posteriori probabilities (APP), where the expectation propagation (EP) algorithm is used to provide an accurate estimation. This new soft equalizer is presented as a block solution, denoted as block-EP (BEP), where the structure of the matrices involved is exploited to reduce the complexity order to O(LN2) , i.e., linear in the length of the channel, L , and quadratic in the frame length, N . The solution is presented in complex-valued formulation within a turbo equalization scheme. This algorithm can be cast as a linear minimum-mean-squared-error (LMMSE) turbo equalization with double feedback architecture, where constellations being discrete is a restriction exploited by the EP that provides a first refinement of the APP. In the experiments included, the BEP exhibits a robust performance, regardless of the channel response, with gains in the range 1.5–5 dB compared with the LMMSE equalization.