On product codes with probabilistic amplitude shaping for high-throughput fiber-optic systems

We consider probabilistic amplitude shaping (PAS) as a means of flexibly varying the spectral efficiency of fiber-optic communication systems. Recently, the PAS architecture originally proposed for a coded modulation (CM) scheme with soft decision decoding has been applied to bit-wise hard decision decoding (HDD) of staircase code. In this paper, we apply the PAS to bit-wise HDD based on the product codes (PCs). We show that the PAS with PCs yields significant gains up to approximately 1 bit/channel use with respect to the baseline scheme using PC with uniform signaling. We also show that the performance of PAS with PC is close to that of PAS with staircase codes. Furthermore, we show that by combining our recently proposed soft-assisted decoder for PCs with the PAS architecture, one can achieve even better operating point than that of PAS with staircase codes decoded using conventional bounded distance decoding