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On the Distribution of Extrinsic L-values in Gray-mapped 16-QAM

Alex Alvarado (Institutionen för signaler och system, Kommunikationssystem) ; Leszek Szczecinski ; Rodolfo Feick
AMC International Wireless Communications and Mobile Computing Conference 2007, IWCMC 2007 (2007)
[Konferensbidrag, refereegranskat]

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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Denna post skapades 2008-01-10. Senast ändrad 2011-03-09.
CPL Pubid: 65511

 

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Institutioner (Chalmers)

Institutionen för signaler och system, Kommunikationssystem (1900-2017)

Ämnesområden

Informations- och kommunikationsteknik
Telekommunikationsteori

Chalmers infrastruktur

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