Enhanced performance of PS-256QAM-OFDM for optical access network

Abstract In this paper, to increase communication capacity and improve receiver sensitivity for optical access networks, probabilistically-shaped orthogonal frequency division multiplexing (PS-OFDM) assisted by constant amplitude zero autocorrelation sequence (CAZAC) is investigated in cost-effective intensity-modulation and direct-detection (IM-DD) system. Since 256-QAM is adopted in PS-OFDM, it can significantly improve spectral efficiency and shaping gain Moreover, we compared the probability shaping scheme with the traditional scheme in the terms of receiver sensitivity and achievable information rate (AIR). Experimental results demonstrate that the performance of probabilistically-shaped OFDM scheme outperforms the traditional OFDM scheme. At the same rate of 6.0 bits/QAM symbol, 2.0-dB performance improvement in both receiver sensitivity and AIR can be achieved employing probabilistic shaping assisted by CAZAC precoding. Meanwhile, a 2.45-Gbit/s/ λ capacity increase can be achieved with the proposed scheme. In addition, a 30.61-Gbit/s/ λ PS-256QAM-OFDM can achieve 20km single-mode fiber (SMF) transmission at BER below 10−6.