Impact of Generator Polynomial on Performance of MAP Turbo Decoder in AWGN Channel

Turbo coding is the most commonly used error correcting scheme in wireless systems resulting in maximum Coding gain. The MAP algorithm is a basic algorithm for turbo decoding. In this paper, authors analyze the performance of turbo MAP algorithm in terms of bit error rate (BER), considering different parameters like signal to noise ratio (SNR), generator polynomials and length of generator polynomial on Additive White Gaussian Noise (AWGN) channel. Simulation of Turbo encoder and Turbo MAP decoder is done. BER and processing time are computed for a range of SNR,considering different generator polynomials of same length and also for generator polynomials of different length, keeping the input constant. Simulation results show that BER for all the generator polynomial of same length is not same for a given SNR. Same is the case with processing time. BER for a given SNR decreases as the length of generator polynomial is increased whereas processing time increases with increase in generator polynomial length.