Modified Viterbi algorithm for efficient optimal decoding of pragmatic-punctured trellis-coded modulation
| Autor: | Fabian Schuh, Andreas Maximilian Schenk, Johannes B. Huber |
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| Rok vydání: | 2014 |
| Předmět: |
Theoretical computer science
Iterative Viterbi decoding Constellation diagram Data_CODINGANDINFORMATIONTHEORY Sequential decoding Viterbi algorithm Puncturing symbols.namesake Convolutional code symbols Trellis modulation Algorithm Soft output Viterbi algorithm Computer Science::Information Theory Mathematics |
| Zdroj: | 2014 8th International Conference on Signal Processing and Communication Systems (ICSPCS). |
| DOI: | 10.1109/icspcs.2014.7021132 |
| Popis: | In classic trellis-coded modulation (TCM) signal constellations of twice the cardinality are applied when compared to an uncoded transmission enabling transmission of one bit of redundancy per PAM-symbol, i.e., rates of K when 2K+1 denotes the cardinality of the signal constellation. In order to support different rates, multi-dimensional (i.e., D-dimensional) constellations had been proposed by means of combining subsequent one- or two-dimensional modulation steps, resulting in TCM-schemes with D 1 bit redundancy per real dimension. In contrast we propose in this paper to perform rate adjustment for TCM by means of puncturing the convolutional code (CC) on which a TCM-scheme is based on. Even though TCM is a topic that has received a lot of attention over the years, the problem of optimal and complexity efficient decoding of a punctured convolutional encoder in TCM was not yet solved without some drawbacks. Here we overcome this problems by usage of a time-variant trellis following the nontrivial mapping of the output symbols of the CC to signal points. For this, some modifications of the Viterbi-decoder are presented and good generator polynomials for the CC as well as corresponding puncturing schemes are given. The proposed approach offers several decisive advantages over multidimensional TCM w.r.t. flexibility and complexity. |
| Databáze: | OpenAIRE |
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