Search

Your search keyword '"JIANG Hexun"' showing total 47 results
Start Over Author "JIANG Hexun"
47 results on '"JIANG Hexun"'

1. Multicarrier Modulation-Based Digital Radio-over-Fibre System Achieving Unequal Bit Protection with Over 10 dB SNR Gain

Author

Xu, Yicheng, Zhu, Yixiao, Zeng, Xiaobo, Fu, Mengfan, Jiang, Hexun, Yi, Lilin, Hu, Weisheng, and Zhuge, Qunbi

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

We propose a multicarrier modulation-based digital radio-over-fibre system achieving unequal bit protection by bit and power allocation for subcarriers. A theoretical SNR gain of 16.1 dB is obtained in the AWGN channel and the simulation results show a 13.5 dB gain in the bandwidth-limited case.

Published
2023

2. Four-dimensional direct detection with Jones space optical full-field recovery

Author

Wu, Qi, Zhu, Yixiao, Jiang, Hexun, Fu, Mengfan, Zhang, Yikun, Zhuge, Qunbi, and Hu, Weisheng

Subjects
Physics - Optics, Physics - Instrumentation and Detectors
Abstract

Data centers, the engines of the global Internet, are supported by massive high-speed optical interconnects. In optical fiber communication, the classic direct detection obtains only the intensity of the optical field, while the coherent detection counterpart utilizes both phase and polarization diversities at the expense of beating with a narrow-linewidth and high-stable local oscillator (LO). Herein, we propose and demonstrate a four-dimensional Jones space optical field recovery (4-D JSFR) scheme without LO. The information encoded on the intensity and phase of both polarizations can be captured by the polarization-diversity full-field receiver structure and subsequently extracted through deep neural network-aided field recovery. It achieves similar electrical spectral efficiency as standard intradyne coherent detection. The fully recovered optical field can extend the transmission distance beyond the power fading limitation induced by fiber chromatic dispersion. Furthermore, the LO-free advantage makes 4-D JSFR suitable for monolithic photonic integration, offering a spectrally efficient and cost-effective candidate for large-scale data center applications. Our results could motivate a fundamental paradigm shift in the optical field recovery theory and future optical transceiver design., Comment: 29 pages, 7 figures

Published
2022

3. Optical Field Recovery in Jones Space

Author

Wu, Qi, Zhu, Yixiao, Jiang, Hexun, Zhuge, Qunbi, and Hu, Weisheng

Subjects
Electrical Engineering and Systems Science - Signal Processing, Physics - Optics
Abstract

Optical full-field recovery makes it possible to compensate for fiber impairments such as chromatic dispersion and polarization mode dispersion (PMD) in the digital signal processing. For cost-sensitive short-reach optical networks, some advanced single-polarization (SP) optical field recovery schemes are recently proposed to avoid chromatic dispersion-induced power fading effect, and improve the spectral efficiency for larger potential capacity. Polarization division multiplexing (PDM) can further double both the spectral efficiency and the system capacity of these SP carrier-assisted direct detection (DD) schemes. However, the so-called polarization fading phenomenon induced by random polarization rotation is a fundamental obstacle which prevents SP carrier-assisted DD systems from polarization diversity. In this paper, we propose a receiver of Jones-space field recovery (JSFR) to realize polarization diversity with SP carrier-assisted DD schemes in Jones space. Different receiver structures and simplified recovery procedures for JSFR are explored theoretically. The proposed JSFR pushes the SP DD schemes towards PDM without extra optical signal-to-noise ratio (OSNR) penalty. In addition, the JSFR shows good tolerance to PMD since the optical field recovery is conducted before polarization recovery. In the concept-of-proof experiment, we demonstrate 448-Gb/s reception over 80-km single-mode fiber using the proposed JSFR based on 22 couplers. Furthermore, we qualitatively compare the optical field recovery in Jones space and Stokes space from the perspective of the modulation dimension. Qualitatively, we compare the optical field recovery in the Jones space and Stokes space from the perspective of the modulation dimension., Comment: 8 pages and 9 figures

Published
2022
Full Text
View/download PDF

4. An Interpretable Mapping from a Communication System to a Neural Network for Optimal Transceiver-Joint Equalization

Author

Zhai, Zhiqun, Jiang, Hexun, Fu, Mengfan, Liu, Lei, Yi, Lilin, Hu, Weisheng, and Zhuge, Qunbi

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

In this paper, we propose a scheme that utilizes the optimization ability of artificial intelligence (AI) for optimal transceiver-joint equalization in compensating for the optical filtering impairments caused by wavelength selective switches (WSS). In contrast to adding or replacing a certain module of existing digital signal processing (DSP), we exploit the similarity between a communication system and a neural network (NN). By mapping a communication system to an NN, in which the equalization modules correspond to the convolutional layers and other modules can been regarded as static layers, the optimal transceiver-joint equalization coefficients can be obtained. In particular, the DSP structure of the communication system is not changed. Extensive numerical simulations are performed to validate the performance of the proposed method. For a 65 GBaud 16QAM signal, it can achieve a 0.76 dB gain when the number of WSSs is 16 with a -6 dB bandwidth of 73 GHz.

Published
2021
Full Text
View/download PDF

10. Multicarrier-Modulation-Based Digital Radio-Over-Fiber System Achieving Unequal Bit Protection With Over 10 dB SNR Gain

Author

Xu, Yicheng, Zhu, Yixiao, Zeng, Xiaobo, Fu, Mengfan, Jiang, Hexun, Hu, Weisheng, and Zhuge, Qunbi

Abstract

In digital mobile fronthaul, multi-level modulation formats such as 4-level pulse amplitude modulation have been considered as viable solutions for bandwidth-efficient digital radio-over-fiber (DRoF). Unlike standard digital communication of 0/1 bit streams with equal bit importance, the quantized bits of wireless waveforms have varied importance, requiring unequal bit protection in DRoF transmission. In this paper, we propose and experimentally demonstrate a multicarrier-modulation-enabled unequal bit protection (MC-UBP) scheme for DRoF systems. Bit and power allocation are employed among digital subcarriers to ensure the superior performance of more important bits. Under the assumption of an additive white Gaussian noise (AWGN) channel, a theoretical analysis of the MC-UBP scheme is performed, including the theoretical derivation of the signal-to-noise ratio (SNR) of recovered wireless signals and the optimization results of the subcarrier power factors. In the experiment based on a coherent optical system, a SNR enhancement of 16.6 dB is achieved compared with the conventional single carrier scheme, which can support the transmission of up to 16384-QAM wireless signals. Different pre-emphasis filters have been used in the experiment to emulate the diverse transfer responses of the systems. The results indicate that the MC-UBP scheme is suitable for these systems with more than 10 dB SNR gain.

Published
2024
Full Text
View/download PDF

46. Digital pre-distortion using a Gauss-Newton-based direct learning architecture for coherent optical transmitters.

Author

Jiang H, Fu M, Zhu Y, Yi L, Hu W, and Zhuge Q

Abstract

Digital pre-distortion (DPD) is a powerful technique to mitigate transmitter nonlinear distortion in optical transmissions. In this Letter, the identification of DPD coefficients based on the direct learning architecture (DLA) using the Gauss-Newton (GN) method is applied in optical communications for the first time. To the best of our knowledge, this is the first time that the DLA has been realized without training an auxiliary neural network to mitigate optical transmitter nonlinear distortion. We describe the principle of the DLA using the GN method and compare the DLA with the indirect learning architecture (ILA) that uses the least-square (LS) method. Extensive numerical and experimental results indicate that the GN-based DLA is superior to the LS-based ILA, especially in a low signal-to-noise ratio scenario.

Published
2023
Full Text
View/download PDF

47. [Short-term effectiveness of acetabular reconstruction with three-dimensional printed trabecular metal pads in hip revision].

Author

Zhang Z, Zhao J, Huang X, Jiang H, and Xu Z

Subjects
Aged, Female, Follow-Up Studies, Humans, Male, Metals, Middle Aged, Printing, Three-Dimensional, Prosthesis Failure, Reoperation, Retrospective Studies, Treatment Outcome, Acetabulum, Arthroplasty, Replacement, Hip, Hip Prosthesis
Abstract

Objective: To investigate the short-term effectiveness of three-dimensional (3D) printed trabecular metal pads for Paprosky type Ⅲ acetabular defect in hip revision., Methods: Between August 2014 and December 2015, the 3D printed trabecular metal pads were used to repair Paprosky type Ⅲ acetabular defects and reconstruct the annular structure of the acetabulums in 5 cases of primary hip revision. There were 3 males and 2 females, aged from 50 to 72 years, with an average age of 66 years. The time from initial replacement to revision was 10 to 18 years, with an average of 14.4 years. The types of prostheses in primary replacement were non-cemented in 3 cases and cemented in 2 cases. The types of acetabular bone defects were Paprosky type ⅢA in 3 cases and Paprosky type ⅢB in 2 cases. The preoperative Harris score was 34.23±11.67. The height of rotation center of affected hip was (38.17±8.87) mm and the horizontal position was (35.62±9.12) mm., Results: The operation time was 120-180 minutes, with an average of 142 minutes. The intraoperative bleeding volume was 800-1 700 mL, with an average of 1 100 mL. Five patients were followed up 18-24 months (mean, 21 months). At last follow-up, the Harris score was 79.82±8.70, which was significantly higher than that before operation ( t =16.991, P =0.000). At 1 week after operation, the abduction angle of acetabular cup was 38-42° (mean, 39.4 °) and the anteversion angle was 13-18 ° (mean, 14.6°). The height and horizontal position of rotation center of affected hip were (22.08±8.33) mm and (29.03±6.28) mm, respectively, showing significant differences when compared with those before operation ( P <0.05); there was no significant difference when compared with those of healthy hip [(28.62±7.73), (27.29±4.22) mm] ( P >0.05). During the follow-up, there was no complication such as prosthesis loosening, dislocation, or periprosthetic fracture., Conclusion: In hip revision, 3D printed trabecular metal pads can repair Paprosky type Ⅲ acetabular defect, reconstruct the structure of acetabulum, provide a stable supporting structure for the acetabular cup, reconstruct the relatively normal rotation center of the hip joint, avoid iatrogenic bone loss, and achieve satisfactory functional recovery of the hip. The long-term effectiveness needs further follow-up.

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results