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- Alvarado, Alex, 1982, et al.
(författare)
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On the Distribution of Extrinsic L-values in Gray-mapped 16-QAM
- 2007
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Ingår i: AMC International Wireless Communications and Mobile Computing Conference 2007, IWCMC 2007. - New York, NY, USA : ACM. - 1595936955 ; , s. 329-336
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Konferensbidrag (refereegranskat)abstract
- In this paper we address the issue of probabilistic modelling of the extrinsic L-values, used as reliability metrics in the context of bit interleaved coded modulation with iterative demapping (BICM-ID). Starting with a simple piece-wise linear model of the L-values obtained via the max-log approximation, we derive the expressions for the cumulative distribution functions of the L-values, that differentiated produce the desired forms of the probability density functions for Gray-mapped 16-QAM. To illustrate the usefulness of our analytical expressions we applied them to efficiently compute the so-called EXIT functions of the demapper for different values of SNR. The proposed analytical expressions are also compared to the histograms of the L-values obtained through time-consuming simulations.
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