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- Agrell, Erik, 1965, et al.
(author)
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Achieving the Shannon Limit with Probabilistically Shaped BICM
- 2012
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In: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781467325806 ; , s. 2421-2425
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Conference paper (peer-reviewed)abstract
- Probabilistic shaping for bit-interleaved coded modulation (BICM) systems at low signal-to-noise ratio (SNR) is investigated. Using known results for BICM systems with a uniform input distribution, the combinations of input alphabet, input distribution, and binary labeling that achieve the Shannon limit -1.59 dB are fully characterized. It is found that a BICM system achieves the Shannon limit at low SNR if and only if it can be represented as a zero-mean linear projection of a hypercube, which is the same condition as for uniform input distributions. Hence, probabilistic shaping offers no extra degrees of freedom to optimize the low-SNR mutual information of BICM systems, in addition to what is provided by geometrical shaping.
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