Performance of mismatched polar codes over BSCs

A challenging problem related to the design of polar codes is “robustness against channel parameter variations”, as stated in Arıkan's original work. In this paper, we show that mismatched polar codes with a decoder implementation based on an approximation of the polarization transformations proposed in [3] are robust for the class of binary symmetric channels. We carry numerical simulations for the average error performance which show the rate loss incurred by the approximation is rather negligible. Combining the theoretical and experimental analysis, we conclude that mismatched polar codes can achieve rates very close to the true channel capacity for the class of binary symmetric channels.