Bit error rate estimate of finite length codes

A novel method of estimating the BER performance of finite length turbo codes in a binary AWGN channel is proposed. We consider the asymptotes of BER performance at low and high E_b/N₀ resulted from the small and large extrinsic values, respectively. The BER performance curve transitions between two asymptotes in the waterfall region, where the transition probability is approximately obtained by using the SNR transfer characteristic band of extrinsic values in the turbo decoding algorithm. Then, the BER estimate of finite length turbo codes is obtained by using two asymptotes at low and high E_b/N₀ and the transition probability between them.