Probabilistic shaped trellis coded modulation with generalized frequency division multiplexing for data center optical networks

With the requirement for large capacity communication systems, the technology to close the gap between the achievable information rate and the Shannon capacity limit attracts more and more attention. In this paper, we present a novel scheme of trellis coded modulation combined with probabilistic shaping (PS-TCM) in the intensity-modulation/direct detection (IM/DD) system, using generalized frequency division multiplexing (GFDM). The principle of PS-TCM is analyzed with mutual information. We experimentally demonstrate the proposed scheme in the optical GFDM system. The results show that 4 Gb/s PS-TCM-32QAM signal achieves ∼2dB gain over the regular 16QAM signal in the back to back case. After 20 km transmission, the scheme of PS-TCM-32QAM provides 1.8 dB performance gain over that of the regular 16QAM signal. The bandwidth effect of optical filter on the performance of PS-TCM-32QAM signal is analyzed. The proposed scheme has significant gain, flexible spectrum efficiency, and approached Shannon limit, which brings a better trade-off between effectiveness and reliability performance for the multi-carrier optical system.