How can I estimate Bhattacharyya parameter for BSC channel, used for Polar codes In polar codes, the frozen bits in each message are determined through the worst channel, where the relevant parameter is the Bhattacharyya .

How can I estimate Bhattacharyya parameter for BSC channel?
I do not think you can use formula (14) on page 5 of 'How to construct polar codes'. I think you want to compute Bhattacharyya parameters after channel polarization. Hence, you need to compute transition probabilities of synthesized channels firstly, and then compute Bhattacharyya parameters using formula (14) on page 5 of 'How to construct polar codes'. The formula of transition probabilities of synthesized channels is give by Arikan in his TIT paper, but it is not easy to implement it.