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On the Information ...
On the Information Loss of the Max-Log Approximation in BICM Systems
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- Ivanov, Mikhail, 1986 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Häger, Christian, 1986 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Brännström, Fredrik, 1974 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Graell i Amat, Alexandre, 1976 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Alvarado, Alex, 1982 (author)
- University College London (UCL)
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- Agrell, Erik, 1965 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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(creator_code:org_t)
- 2016
- 2016
- English.
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In: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 62:6, s. 3011 - 3025
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Abstract
Subject headings
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- We present a comprehensive study of the information rate loss of the max-log approximation for M-ary pulse-amplitude modulation (PAM) in a bit-interleaved coded modulation (BICM) system. It is widely assumed that the calculation of L-values using the max-log approximation leads to an information loss. We prove that this assumption is correct for all M-PAM constellations and labelings with the exception of a symmetric 4-PAM constellation labeled with a Gray code. We also show that for max-log L-values, the BICM generalized mutual information (GMI), which is an achievable rate for a standard BICM decoder, is too pessimistic. In particular, it is proved that the so-called harmonized GMI, which can be seen as the sum of bit-level GMIs, is achievable without any modifications to the decoder. We then study how bit-level channel symmetrization and mixing affect the MI and the GMI for max-log L-values. Our results show that these operations, which are often used when analyzing BICM systems, preserve the GMI. However, this is not necessarily the case when the MI is considered. Necessary and sufficient conditions under which these operations preserve the MI are provided.
Subject headings
- TEKNIK OCH TEKNOLOGIER -- Elektroteknik och elektronik -- Kommunikationssystem (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Electrical Engineering, Electronic Engineering, Information Engineering -- Communication Systems (hsv//eng)
Publication and Content Type
- art (subject category)
- ref (subject category)
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