Lower bound on BER performance of finite length turbo codes using Gaussian approximation

In this paper, we propose a novel method to obtain the lower bound on the average BER of the finite-length turbo codes in an additive white Gaussian noise (AWGN) channel considering the transition probability of the average BER curve between two asymptotes. For this purpose, we use the SNR TCB chart based on the Gaussian approximation of extrinsic values for each frame.