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Fan Li - IEEE Xplore Author Profile

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Recently, coherent digital subcarrier multiplexing (DSCM) technology has become an attractive solution for next-generation ultra-high-speed datacenter interconnects (DCIs). To meet the requirements of low-cost and low-power consumption in DCI applications, a comprehensive simplification of the coherent DSCM system has been investigated. The pilot-tone-based polarization demultiplexing (PT-PDM) tec...Show More
Equalization-enhanced phase noise (EEPN) can degrade the performance of high baud-rate and long-distance coherent optical transmission systems that use electronic dispersion compensation (EDC). Existing theoretical calculations of EEPN are based on the ideal Nyquist filter, which has an unrealizable brickwall response due to its infinite time-domain extent. In this paper, we generalize the EEPN ca...Show More
In this paper, we introduce a novel performance enhanced cascaded digital–analog radio-over-fiber (ECDA-RoF) scheme achieved by a digital symbol remapping technique for 6G mobile Fronthaul. After the digital symbol remapping, the entropy of the digital part generated by the traditional CDA-RoF scheme will be reduced, indicating an improvement in the channel noise tolerance for this part. Consequen...Show More
The capacity and capacity-achieving distribution for memoryless intensity-modulation and direct-detection (IM-DD) fiber-optic channels are theoretically investigated. Different from coherent fiber-optic channels, we indicate that the capacity-achieving distribution of IM-DD systems should be discussed separately in two cases: 1) IM-DD systems without optical amplifiers, constrained by peak power; ...Show More
In this paper, we introduce a simplified digital resolution enhancer (DRE) achieved by reducing the survived state of the Viterbi algorithm for pre-equalization systems with low-resolution digital-to-analog converters (DACs). The clipping technique is employed based on the simplified DRE to mitigate the impact of quantization noise and improve the signal power. Both clipping and quantization noise...Show More
A low complexity coherent 16×400 Gbit/s datacenter interconnect with 50Gbaud 4SC-16QAM DSCM signal is experimentally demonstrated, enabled by a novel low complexity transceiver IQ skew estimation method and simplified equalizer embedded phase tracking.Show More
We propose a novel precise transceiver IQ skew calibration method utilizing the specially designed training signal for single carrier coherent system. The results show that the estimation error can be within ±0.2ps.Show More
Transceiver in-phase/quadrature (IQ) skew due to device imperfections is one of the major factors restricting the transmission performance of coherent systems. Although two 4 × 4 real-valued multiple-in multiple-out equalizers can address the transceiver IQ skew impairments to some extent, it leads to high computational complexity in the receiver-side digital signal processing. Since the IQ skew i...Show More
Beyond 100G passive optical networks (PONs) will be required to meet the ever-increasing traffic demand in the future. Coherent optical technologies are the competitive solutions for the future beyond 100G PON but also face challenges such as the high computational complexity of digital signal processing (DSP). A high oversampling rate in coherent optical technologies results in the high computati...Show More
Look-up table (LUT) enabled digital pre-distortion (DPD) is an effective means of nonlinear compensation. However, considering the storage requirement and feasibility of training process, the memory length is commonly limited to 3 or 5, which limits the nonlinear compensation performance of LUT-DPD. With the growing demands of high baud rate transmission, the system is more sensitive to nonlinear ...Show More
High spectral efficiency (SE) transmission is a critical topic for next-generation ultra-high-speed optical networks, particularly for intensity-modulation with direct-detection (IM-DD) systems where the degree of freedom for data delivery is severely constrained. In this article, two high SE transmission approaches, namely fast than Nyquist (FTN) and high order modulation formats (HoMF) signaling...Show More
Inter-symbol-interference (ISI) and nonlinear distortions are the major impairments in high-speed short-reach intensity modulation and direct detection (IM-DD) systems. Linear ISI can be well addressed with linear equalizer cascaded maximum likelihood sequence estimation (MLSE), while the nonlinear distortions cannot be effectively compensated in this manner. In this article, a low complexity nonl...Show More
Reduced state DRE for clipping-and-quantization noise elimination is studied with 3-bit DAC. Experiment-results indicate that 99.2% computational complexity reduction can be achieved for 40Gbaud PAM-8 signal, maintaining below 0.2dB ROP penalty at the 1×10-2 threshold, using 5-taps CIR-supported DRE with 5 soft-quantization possibilities.Show More
A low power nonlinear MLSE is proposed, which can compress the transitions in the trellis adaptively. Compared to LUT aided conventional MLSE, up to 90% power consumption can be reduced with neglectable receiver sensitivity penalty.Show More
Based on deep neural network (DNN), intensity modulation and direct detection (IM/DD) system is demonstrated by simulation and 56-GBaud OOK signal is successfully transmitted over 80-km single mode fiber (SMF) with 3-taps post-equalization.Show More
In this paper, we experimentally demonstrated a 2-km 100 Gb/s optical interconnection with pulse-shaped pre-equalized four-level pulse amplitude modulation (PAM-4) signal generated by a 3-bit digital-to-analog converter (DAC) with the aid of channel response-dependent noise shaping (CRD-NS) technique.Show More
Neural network-assisted pre-distortion method is proposed to generate pattern errors with memory length of more than 5 symbols in PAM-8 IM/DD transmission utilizing limited samples as training sequence, which enables an improvement on system performance.Show More
This study proposes a physical layer encryption scheme based on disturbance of data cluster under color seeking mechanism of chaotic sequence which is generated by Brownian motion determined by keys aiming to improve security of coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. Chaotic sequences with good randomness and unpredictability are endowed with a unique color c...Show More
In this article, a joint application of simplified Tomlinson-Harashima precoding (THP) and M-log-maximum a posteriori probability (M-log-MAP) decoder at transceivers is proposed for low complexity faster than Nyquist (FTN) 4-ary pulse amplitude modulation (PAM4) signaling. A THP with only two taps is applied at the transmitter for FTN-induced inter-symbol interference elimination and equalization-...Show More
We experimentally demonstrate a single-carrier 400G Metro/regional communications based on 60-GBaud PDM-16QAM over 430-km SMF-28. Joint GPD and GSOP and 4×4 MIMO LMS equalizer are adopted to compensate Rx/Tx I/Q imbalance, and simplified MLSE with 99.61% computational complexity reduction is employed to mitigate channel bandwidth constraint.Show More
Photonics-aided millimeter wave (MMW) Orthogonal frequency division multiplexing (OFDM) system is a novel approach to realize the joint radar and communication system. The phase noise introduced by the laser will degrade the system performance. In this paper, we analyze the mechanism of phase noise acting on OFDM radar system. A method that combines chirp-Z transform (CZT) and compensation enabled...Show More
Bandwidth limitation introduced inter-symbol interference (ISI) is the major impediment for high baud rate intensity modulation and direct detection (IM/DD) system with commercial devices. Least mean square (LMS) criterion based feedforward equalizer (FFE) is the most common method to eliminate ISI in single-carrier system. However, there is a tradeoff between the residual ISI and enhanced noise w...Show More
A passive optical network (PON) with low cost and high capacity has been explored and recommended for supporting the emerged commercial mobile fronthaul, resident, and industry services. To meet the requirement in the future, the development of the PON, including cost, data rate, and latency, is still being driven by utilizing an improved PON architecture, transmitter, and receiver. In this paper,...Show More
In this paper, a channel response dependent noise shaping (CRD-NS) technique is proposed and experimentally demonstrated for the pre-equalized discrete multi-tone (DMT) signal transmission in intensity modulation and direct detection (IM/DD) system with a low-resolution digital-to-analog converter (DAC). Compared with traditional NS technique, the proposed CRD-NS technique can bring signal-to-quan...Show More