A multi-repeat mapping based probabilistic shaping coding method applied to data center optical networks

In recent years, the technology to narrow the gap between the achievable information rate and the Shannon capacity limits attracts increasing attention. In this paper, a probabilistic shaping coding method based on multi-repeat mapping is proposed. By applying block coding to the information sequences with our method, we transform the modulated constellation points from a uniform distribution to the desired distribution. Rate adaption and controllable distribution are achieved by adjusting the block length and the size of different mapping sets. The proposed algorithm has better coding efficiency, low storage and computational complexity, so is more suitable for data center optical networks. An experiment that demonstrates probabilistically shaped data transmission is successfully conducted over 10 km standard single-mode fiber (SSMF) with 16 quadrature amplitude modulation – discrete multi-tone (16-QAM-DMT). We evaluate our method for a set of code rates, i.e., 16 QAM with code rate 6/8, 7/8 and 9/12. The experimental results show that the improved signal to noise ratios (SNR) can be up to 1.1 dB at a bit error rate (BER) of 10^-3 after using the proposed method for probabilistic shaping.