We consider the effect of LLR saturation on belief propagation decoding oflow-density parity-check codes. Saturation occurs universally in practice andis known to have a significant effect on error floor performance. Our focus ison threshold analysis and stability of density evolution. We analyze the decoder for certain low-density parity-check code ensemblesand show that belief propagation decoding generally degrades gracefully withsaturation. Stability of density evolution is, on the other hand, ratherstrongly affected by saturation and the asymptotic qualitative effect ofsaturation is similar to reduction of variable node degree by one.
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