EXIT charts analysis of a root-like bit mapping for LDPC-coded QAM systems
Autor: | Fernanda Smith, Evaldo Pelaes, Bartolomeu F. Uchoa-Filho |
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Rok vydání: | 2017 |
Předmět: |
Theoretical computer science
Bit manipulation Computer science Orthogonal frequency-division multiplexing Applied Mathematics 020206 networking & telecommunications 02 engineering and technology Rule of thumb Bit field QAM Bit (horse) Computational Theory and Mathematics Artificial Intelligence Signal Processing 0202 electrical engineering electronic engineering information engineering 020201 artificial intelligence & image processing Computer Vision and Pattern Recognition Electrical and Electronic Engineering Statistics Probability and Uncertainty Low-density parity-check code Tanner graph Algorithm |
Zdroj: | Digital Signal Processing. 70:39-48 |
ISSN: | 1051-2004 |
DOI: | 10.1016/j.dsp.2017.07.019 |
Popis: | The error performance of LDPC-coded QAM systems, such as those implied by the G.hn and IEEE 802.11n standards, can be considerably improved by bit mapping techniques. Recently, a simple root-like bit mapping has been proposed by the authors. It is based on the principle that bits transmitted through “good” sub-channels can help bits transmitted through “bad” sub-channels. This can be made possible through some restrictions to be imposed on the associated Tanner graph. In this paper, we perform an optimization of the root-like bit mapping through EXIT charts analysis. We show that this mapping has the advantage of a reduced optimization search space when applied to single-carrier based systems. Moreover, in situations where the search space is not so reduced, such as in OFDM-based applications, we arrive at a rule of thumb associated with the bit mapping constraints that practically eliminates the need for an optimization. It means that the root-like is a low-complexity bit mapping scheme that can be very useful in practical systems. The work is concluded with a study of the impact of the level of reliability imbalance across the sub-channels on the performance of the root-like bit mapping. |
Databáze: | OpenAIRE |
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