Improved performance SOVA turbo decoder

A novel approach for improving the performance of the soft-output Viterbi algorithm (SOVA) when applied to turbo decoding is proposed. Based upon a modified two-step scaling factor approach for the decoder´s extrinsic information, it is shown that the proposed technique reduces significantly the error floor present in previous SOVA-based turbo decoding techniques. Various computer simulated bit error rate (BER) performance evaluation results for binary phase shift keying (BPSK) signals transmitted over the additive white Gaussian noise (AWGN) and flat Rician fading channels clearly indicate that for large interleaver sizes and high numbers of decoding iterations no error floor is observed for BERs as low as 10^-6