Enhancement of cross-entropy based stopping criteria via turning point indicator

Cross-entropy (CE) based stopping criteria is known for its early termination capability of the turbo decoding iterations without scarifying its performance, in terms of bit error rate (BER). This advantage, however, performs well in high signal-to-noise ratio (SNR) albeit requiring infinite iterations at low SNR, thereby resulting in more unwanted computations and decoding delays. In this paper, a simple turning point (TP) measurement from the BER and average iteration number (AIN) graphs of the Genie stopping criterion has been introduced. The motivation is twofold; to terminate the iteration at the early stage in low SNR and maintaining the same level of performance of the existing method in high SNR, by using the proposed TP measurement. From the simulation results, the enhanced CE-based stopping criteria improve the early termination in low SNR and maintain the BER performance for various frame sizes compared to existing stopping criteria.