Explanation of polar decoding? Polar decoding, according to Arikan's paper, can be decoded using a successive cancellation (SC) decoder, which is based on calculating the likelihood ratio, as seen in the image below.



How can I calculate equations 2 and 3 in the above image?
For example, assuming that $N=4$ and that we are using an AWGN channel with $\sigma=0.987$.
Shor is probably referring to this fantastic lecture by Emre Telatar that walks you through the steps in polar coding. Do watch it! In doing so, you shall see that the best mental model to have in mind while trying to wrap your head around the polar code is the erasure channel.