Improved BICM iterative decoding with hard-decision feedback

TitleImproved BICM iterative decoding with hard-decision feedback
Publication TypeConference Paper
Year of Publication2005
AuthorsLiu, J. T. - L., and L. Lampe
Conference NameCommunications, Computers and signal Processing, 2005. PACRim. 2005 IEEE Pacific Rim Conference on
Pagination73 - 76
Date Publishedaug.
Keywordsautomatic repeat request, bandwidth-efficient transmission, bit-interleaved coded modulation, channel coding, decoding complexity, demapper, fading channels, hard-decision feedback, interleaved codes, Iterative Decoding, modulation coding, power-efficient transmission, pragmatic truncation schemes, Rayleigh channels, Rayleigh fading channel, subsequent decoding

Bit-interleaved coded modulation (BlCM) enables power- and bandwidth-efficient transmission over fading channels. Power efficiency can be further improved if iterative decoding (ID) is applied, so-called BICM-ID. In this paper, we consider BICM-ID with hard-decision feedback as originally proposed by Li and Ritcey (1999) for low-complexity ID. We analyze the reliability of the soft output of the hard-decision feedback aided demapper, the inner decoder of BICM-ID. From this we find that a simple truncation of these output values significantly improves reliability in subsequent decoding iterations and thus, enhances convergence of ID. We propose two pragmatic truncation schemes and show by means of simulations that gains of more than 3 dB in power efficiency over conventional BICM-ID are achieved for the Rayleigh fading channel with no increase in decoding complexity.


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