A decoding algorithm for turbo product codes using optimality test and amplitude clipping

This paper presents an iterative soft-input/soft-output (SISO) decoder for product code using optimality test and amplitude clipping. A modified expression for computing the soft-output of SISO decoder is proposed. The correlation discrepancy is employed to provide an optimality test on the decision codeword. The optimality test is performed in row and column decoding to evaluate the reliability of row and column decision codewords. Based on the optimality test, the variable reliability factor is introduced for optimization of turbo decoding. A stopping criterion with very little performance degradation is also designed for turbo decoding of product codes by using the optimality test. Besides, the amplitude clipping is employed to improve the performance of turbo product code. Simulation results on the performance of the introduced SISO decoder are presented.