Evaluation of Sum-product Decoding Iteration Number for LDPC Coding FEC in Spectrum Suppressed Transmission

In recent years, a new concept called NTN (Non-terrestrial Network) has been considered in Beyond 5G/6G to expand the communication area in three dimensions, and the demand for satellite communications is expected to increase further in the future. To solve this problem, spectrum suppressed transmission has been proposed. In previous studies, the number of LDPC coding sum-product decoding iterations in single career QPSK modulations have been evaluated only 10 times. In this paper, we optimize the number of decoding iterations for each suppression rate when LDPC coding in single career QPSK modulations are applied to spectrum suppressed transmission, and quantitatively evaluate the improvement effect of BER performances at the optimal number of iterations and the processing delay time depending on the number of decoding iterations.