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Approaching Terabits per Carrier Metro-Regional Transmission Using Beyond-100GBd Coherent Optics with Propabilistically Shaped DP-64QAM Modulation
摘要： This research work proposed and experimentally demonstrated beyond-100GBd probabilistically-shaped coherent optics that support transmission of ~1.2 Tbps coded line rate and ~0.9 Tbps net bit rate per optical carrier over metro-regional distances. Pursuing next-generation transmission systems having both high capacity approaching Terabits per wavelength and high spectral efficiency requires engineering efforts from different aspects, which may includes the enhancement of analog-to-digital or digital-to-analog (AD/DA) interfaces, the improvement of channel characteristics, and also the realization of better receiver sensitivities, preferably through DSP techniques such as probabilistic shaping (PS). By doing so, this work achieved single-channel and 112.5GHz-WDM transmission of 900G wavelengths over 800 km and 400 km, respectively, which employed PS DP-64QAM modulation format at 105 GBd, yielding a net spectral efficiency of 8.05 bits/s/Hz. Such a high symbol rate was demonstrated using a commercially available DAC unit without band-interleaving. The enhanced optical channel consists of ITU-T G.654 compliant Terawave SLA+ fiber spans with backward-pumped Raman amplifiers. In addition, with the same PS DP-64QAM modulation format and the same enhanced channel, this research work also demonstrated that 400G wavelengths can be delivered over 2,800 km supporting long-haul applications.
关键词： quadrature amplitude modulation,probabilistic shaping,optical fibers,Coherent optical communications
更新于2025-09-23 15:23:52
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Implications of Distributed Link Polarization Dependent Loss on Bit-Wise Achievable Information Rates for Probabilistically Shaped and Uniform DP 64-QAM
摘要： The statistical behaviours of bit-wise achievable information rates (BW AIRs) and effective signal-to-noise ratios (SNRs) due to polarization dependent loss (PDL) are experimentally characterized for probabilistically shaped and uniform dual-polarization 64-ary quadrature amplitude modulation (DP 64-QAM) with a bit rate of 250 Gb/s. A single-span recirculating loop is used to emulate distributed link PDL. Histograms for the BW AIR and effective SNR following offline signal processing resemble shifted, mirror-image Maxwell probability density functions for both constellations and two different per-loop PDL values. For a transmission distance of 1200 km and a per-loop PDL of 1.3 dB, the outage probabilities for the shaped and uniform constellations are estimated to be 1.1 × 10?3 and 4.4 × 10?1, respectively. Moreover, for an outage probability ≤ 4.0 × 10?3, the increase in transmission distance due to shaping is reduced by 50% compared to that for PDL free transmission.
关键词： Probabilistic shaping,coherent optical fiber transmission systems,polarization dependent loss
更新于2025-09-23 15:22:29
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Introducing Enumerative Sphere Shaping for Optical Communication Systems with Short Blocklengths
摘要： Probabilistic shaping based on constant composition distribution matching (CCDM) has received considerable attention as a way to increase the capacity of fiber optical communication systems. CCDM suffers from significant rate loss at short blocklengths and requires long blocklengths to achieve high shaping gain, which makes its implementation very challenging. In this paper, we propose to use enumerative sphere shaping (ESS) and investigate its performance for the nonlinear fiber optical channel. ESS has lower rate loss than CCDM at the same shaping rate, which makes it a suitable candidate to be implemented in real-time high-speed optical systems. In this paper, we first show that finite blocklength ESS and CCDM exhibit higher effective signal-to-noise ratio than their infinite blocklength counterparts. These results show that for the nonlinear fiber optical channel, large blocklengths should be avoided. We then show that for a 400 Gb/s dual-polarization 64-QAM WDM transmission system, ESS with short blocklengths outperforms both uniform signaling and CCDM. Gains in terms of both bit-metric decoding rate and bit-error rate are presented. ESS with a blocklength of 200 is shown to provide an extension reach of about 200 km in comparison with CCDM with the same blocklength. The obtained reach increase of ESS with a blocklength of 200 over uniform signaling is approximately 450 km (approximately 19%).
关键词： optical communication systems,enumerative sphere shaping,probabilistic shaping,fiber nonlinearity,Constant composition distribution matching
更新于2025-09-19 17:13:59
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402.7-Tb/s MDM-WDM transmission over weakly coupled 10-mode fiber using rate-adaptive PS-16QAM signals
摘要： The mode-division-multiplexing (MDM) transmission technique using a few-mode fiber (FMF) has been investigated to overcome the theoretical limitation of the transmission capacity of a single-mode fiber. In MDM transmission, multiple-input multiple-output (MIMO) digital signal processing (DSP) is generally required on the receiver side to compensate for the modal crosstalk (XT) between the spatial modes. However, the computational cost is high, especially for high-order MDM systems that use many spatial modes. To reduce the MIMO matrix size, MDM transmission with partial MIMO-based DSP has been proposed using weakly coupled FMFs. The modal XT in such fibers can be suppressed by a special fiber design; however, the modal XT still remains and strongly limits the signal-to-noise-ratio (SNR) and capacity. To further increase the capacity for a given SNR, an optimization of the modulation format is significant. Recently, probabilistic shaping (PS) has received attention since it can gradually change the entropy of a modulation format and maximize the capacity for a given SNR. In this work, we demonstrate weakly coupled 10-mode-multiplexed transmission with four 4×4 MIMOs and two 2×2 MIMOs using rate-adaptive PS-16QAM signals over 48-km FMF, achieving a record transmission capacity of 402.7 Tb/s in 125-μm cladding single-core fiber transmission experiments. Furthermore, we also show the possibility of a further capacity increase by adjusting the entropies of the PS-16QAM signals depending on the spatial mode.
关键词： high-capacity transmission,probabilistic shaping,mode-division multiplexing (MDM),Few-mode-fiber (FMF),rate optimization,coded modulation
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Research on Adaptive Optimal Shaping Gain Selection MethodBased on Huffman Coding
摘要： In this paper, an adaptive optimal shaping gain selection method based on huffman coding is proposed. By non-uniform mapping, the input signal satisfies the optimal (secondary) distribution under different SNR, that is, the input signal is infinitely close to Maxwell Boltzmann distribution, so that the channel capacity wirelessly approaches the Shannon limit. The method not only improves the transmission performance of the system, increases the shaping gain, but also saves the algorithm complexity and system cost, and realizes the optimal distribution of the optimal (secondary)input signals under different SNR, thereby infinitely approaching the high-speed transmission of the channel capacity.
关键词： adaptive,Shannon limit,shaping gain,probabilistic shaping
更新于2025-09-16 10:30:52
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Phase Uniformly Distributed Circular MQAM Combined With Probabilistic Shaping for PM-CO-OFDM Systems in Satellite-to-Ground Optical Communications
摘要： Due to the rapid growth of high-resolution services, low earth orbit satellite-to-ground (LEO-StG) optical communications are expected to provide higher speed and better receiver sensitivity transmission. Here, we propose a phase uniformly distributed circular m-ary quadrature amplitude modulation (MQAM) combined with probabilistic shaping (PS) scheme for polarization multiplexing coherent optical orthogonal frequency-division multiplexing (PM-CO-OFDM) systems in LEO-StG communications to achieve high capacity transmission and improve receiver sensitivity as well as linewidth tolerance. In such scheme, the radius ratio of the circular 16/32QAM is optimized to maximize the minimum Euclidean distance (MED), and the constellation points of each ring are uniformly distributed to maximize the phase space of adjacent constellation points. Besides, the circular 16/32QAM is combined with probabilistic shaping (PS) to further increase the MED under the constraint of average transmit power. Simulation results of such circular 16/32QAM combined with PS scheme under different turbulence channels not only demonstrate its feasibility, but also show the improvements in receiver sensitivity and linewidth tolerance compared with regular 16/32QAM under same entropy. The improvement of receiver sensitivity is also experimentally validated. The superiorities of such scheme make it highly desirable for potential application in long-reach, non-relay, and high capacity LEO-StG optical communications.
关键词： orthogonal frequency-division multiplexing,Geometric shaping,satellite-to-ground,probabilistic shaping
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - A Poldemux Scheme Using Extended Kalman Filter in Probabilistic Shaping Stokes Vector Direct Detection System
摘要： We propose a Kalman filter based PolDemux scheme to cope with probabilistically shaped 16QAM signals in Stokes vector direct detection system. It can track the SOP variation up to 2Mrad/s at a relative lower OSNR.
关键词： Stokes vector direct detection,Extended Kalman filter,Probabilistic shaping,Rotation of state of polarization
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Probabilistically shaped 100G IM-DD optical interconnection
摘要： In this paper, we present a review about our recent works optical interconnection applications. PS for PAM and DMT were introduced for achieving 100-Gbps over IM-DD VCSEL-MMF optical interconnection link.
关键词： IM-DD,100G,Probabilistic shaping,optical interconnection
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Probabilistic Shaping for Direct Detection Transmission With Kramers-Kronig Receiver
摘要： We introduce probabilistic shaping into direct detection system with Kramers-Kronig receiver to further improve the performance. Simulation results show that there are 0.53/0.86/1.12dB OSNR improvements by transmitting PS-16/64/256QAM signal compared with the uniform 16/64/256QAM signal.
关键词： Kramers-Kronig,direct detection,probabilistic shaping
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Post Equalization Scheme Based on Deep Neural Network for a Probabilistic Shaping 128 QAM DFT-S OFDM Signal in Underwater Visible Light Communication System
摘要： We have presented a post equalization scheme based on Deep Neural Network (DNN) for DFT-S OFDM modulation using (PS) technique in underwater visible light communication (VLC) system. By this method, we successfully demonstrated a data rate of 1.74Gbit/s PS128QAM DFT-S OFDM modulation over 1.2meter underwater optical transmission with bit error rate (BER) below 7% FEC threshold of 3.8×10-3. Compared to the typical PS128QAM DFT-S OFDM modulation without DNN, the proposed method would lead to an improvement of system capacity of 5.4% by increasing the data rate by 90 Mbps. The experimental results validate that the proposed DNN-based post equalization scheme for odd order QAM PS technique can be a promising solution for future high speed underwater VLC system.
关键词： Probabilistic Shaping (PS),odd order QAM,Deep Neural Network (DNN),Underwater VLC,Discrete Fourier Transform-Spread (DFT-S) OFDM
更新于2025-09-16 10:30:52