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Journal of Electrical and Computer Engineering
Volume 2012, Article ID 394809, 15 pages
http://dx.doi.org/10.1155/2012/394809
Research Article

Two-Dimensional Iterative Processing for DAB Receivers Based on Trellis-Decomposition

1Catena Radio Design, Science Park Eindhoven, Ekkersrijt 5228, 5692 EG Son en Breugel, The Netherlands
2Department of Electrical Engineering, Technische Universiteit Eindhoven, Den Dolech 2, Postbus 513, 5600 MB Eindhoven, The Netherlands

Received 6 July 2011; Revised 14 October 2011; Accepted 17 October 2011

Academic Editor: Chirn Chye Boon

Copyright © 2012 Wim J. van Houtum and Frans M. J. Willems. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We investigate iterative trellis decoding techniques for DAB, with the objective of gaining from processing 2D-blocks in an OFDM scheme, that is, blocks based on the time and frequency dimension, and from trellis decomposition. Trellis-decomposition methods allow us to estimate the unknown channel phase since this phase relates to the sub-trellises. We will determine a-posteriori sub-trellis probabilities, and use these probabilities for weighting the a-posteriori symbol probabilities resulting from all the sub-trellises. Alternatively we can determine a dominant sub-trellis and use the a-posteriori symbol probabilities corresponding to this dominant sub-trellis. This dominant sub-trellis approach results in a significant complexity reduction. We will investigate both iterative and non-iterative methods. The advantage of non-iterative methods is that their forwardbackward procedures are extremely simple; however, also their gain of 0.7 dB, relative to two-symbol differential detection (2SDD) at a BER of 10-4, is modest. Iterative procedures lead to the significantly larger gain of 3.7 dB at a BER of 10-4 for five iterations, where a part of this gain comes from 2D processing. Simulations of our iterative approach applied to the TU-6 (COST207) channel show that we get an improvement of 2.4 dB at a Doppler frequency of 10 Hz.