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Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping
Published on: March 20, 2017
Ultra-high-order QAM modulation approach based on local constellation decomposition joint shaping
Abstract:
This article proposes a local constellation decomposition joint shaping scheme for ultra-high-order quadrature amplitude modulation (QAM) signals. The method first applies probabilistic shaping (PS) to the global constellation, followed by decomposition into local constellations, geometric shaping (GS) at the local level, and recombination for transmission. Delta-sigma modulation (DSM) is employed to facilitate the transmission of ultra-high-order 16384QAM in an intensity modulation direct detection (IMDD) system. Simulation studies are conducted to evaluate transmission performance under varying information entropy levels. The results demonstrate that, for the same information entropy, the bit error rate (BER) performance of 16384QAM with the proposed joint shaping scheme and DSM outperforms that of conventional 16384QAM with DSM. Experimental validation over 25 km single-mode fiber (SMF) further confirms the effectiveness of the proposed approach for ultra-high-order communication systems based on DSM. Additionally, the receiver sensitivity of the system improves by approximately 0.6 dB for every 1 bit/symbol reduction in information entropy.
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