On the scaling of Polar Codes: II. The behavior of un-polarized channels

S. Hamed Hassani; Kasra Alishahi; Rudiger Urbanke

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arXiv · 1002.3187

On the scaling of Polar Codes: II. The behavior of un-polarized channels

S. Hamed Hassani·Kasra Alishahi·Rudiger Urbanke

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Abstract

We provide upper and lower bounds on the escape rate of the Bhattacharyya process corresponding to polar codes and transmission over the the binary erasure channel. More precisely, we bound the exponent of the number of sub-channels whose Bhattacharyya constant falls in a fixed interval $[a,b]$. Mathematically this can be stated as bounding the limit $\lim_{n \to \infty} \frac{1}{n} \ln \mathbb{P}(Z_n \in [a,b])$, where $Z_n$ is the Bhattacharyya process. The quantity $\mathbb{P}(Z_n \in [a,b])$ represents the fraction of sub-channels that are still un-polarized at time $n$.

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S. Hamed Hassani, Kasra Alishahi, Rudiger Urbanke. 2010-02-18. On the scaling of Polar Codes: II. The behavior of un-polarized channels. https://arxiv.org/abs/1002.3187

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