Author Affiliations
Abstract
1 Beijing Key Laboratory of Space-Ground Interconnection and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
2 Institute of Electronic and Information Industry, China Center for Information Industry Development, Beijing 100876, China
3 Department of Electronic Engineering, College of Information Science and Technology, Jinan University, Guangzhou 510632, China
This paper proposes a hybrid layered asymmetrically clipped optical (HLACO) single-carrier frequency-division multiplexing (SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines layered asymmetrically clipped optical (LACO)-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency-division multiplexing (OFDM)-based dimmable schemes and further enhancing the system performance. Compared to the HLACO-OFDM-based dimming scheme, it obtains a lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit·s-1·Hz-1 within the dimming range of 30%–70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.
dimming control single-carrier frequency-division multiplexing visible light communication spectral efficiency complexity Chinese Optics Letters
2021, 19(4): 040601
Author Affiliations
Abstract
State Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
In this Letter, we propose a scheme that integrates a diversity-combining technique with asymmetrical clipping optical orthogonal frequency-division multiplexing (ACO-OFDM) based on a discreet Hartley transform (DHT). Simulations are demonstrated for the DHT-based ACO-OFDM system with a diversity-combining technique. The simulation results indicate that when the optimal weighting factor is chosen, the bit error rate (BER) performance is improved by about 2 dB when the binary phase-shift keying (BPSK) is modulated and about 3 dB when the 16 pulse-amplitude modulation is modulated. Additionally, experiments are presented to verify the feasibility of diversity-combining DHT-based ACO-OFDM. In the transmission experiments, a BPSK-modulated DHT-based ACO-OFDM with a diversity-combining receiver is realized, which improves the BER performance by 1.5 and 1.3 dB for a span length of back-to-back and a 50 km standard single-mode fiber, respectively.
Chinese Optics Letters
2015, 13(Suppl): S20605
Author Affiliations
Abstract
1 State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
2 College of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
We study the decoding performance of low-density parity-check (LDPC) code based on Watermark scheme under different percentages of water-mark bits over 100 Gb/s differential quadrature phase shift keying (DQPSK) high-speed optical communication system. We also find the optimum percentage of water-mark bits according to the performance comparison. Simulation result shows an improvement of 0.5 dB net code gain by using the optimum Watermark scheme at a post-forward error correction bit error rate (BER) of 10-9, comparing with the traditional log-likelihood ratios belief propagation decoding algorithm. Also, for the same BER, there is a decrease in the number of iterations used in LDPC decoding.
060.4510 Optical communications 110.7348 Wavefront encoding 150.1135 Algorithms Chinese Optics Letters
2015, 13(s1): S10601
Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
We demonstrate a new scheme for generation of optical frequency comb (OFC) based on cascade modulators, 23 comb lines within 0.5 dB spectral power variation are obtained. An optical finite impulse response (FIR) filter is introduced for suppression of amplified spontaneous emission noise. It is shown that carrier-to-noise-ratio of the OFC generated by this scheme can be as high as 38.8 dB with 12 dB improvement by using a 16-tap FIR filter, and the error vector magnitude performances of loaded Nyquist-16 quadrature amplitude -modulation signal is improved from 14.20% to 7.44%.
060.0060 Fiber optics and optical communications 060.5060 Phase modulation 350.2460 Filters, interference Chinese Optics Letters
2015, 13(1): 010605
1 北京邮电大学
2 信息光子学与光通信国家重点实验室,北京 100876
在正交频分多址无源光网络上行传输中，不同光网络单元的上行信号如果采用相同波长的不同激光器将会产生光拍频噪声,使得光网络单元的无色性难以实现.本文以正交频分多址无源光网络为研究对象，通过对系统结构的研究和相关公式的推导，分析了信号上行传输中光拍频噪声的产生原因和避免方式.针对下行发送上行载波结合光线路终端相干接收的光拍频噪声避免方案进行了仿真研究.分析了系统的抗色散方案以及色散累积和训练序列长度对系统性能的影响，给出了优化的参数设置，为系统实际应用提供了理论参考.
光通信 无源光网络 仿真分析 正交频分多址无源光网络 光拍频噪声 物理层损伤 optical communication passive optical network orthogonal division multiple access pon optical beating interference physical layer impairments
北京邮电大学信息光子学与光通信国家重点实验室, 北京 100876
随着光纤通信系统容量的增加和信道间隔的降低,非线性噪声必然成为限制光传输系统发展的重要因素。提出了一种比较准确的仿真模型用来估计把非线性噪声当作加性高斯处理的高斯噪声(GN)模型的适用范围，同时对该模型进行了大量的仿真验证，包括不同的光纤类型和不同的调制格式。仿真结果证明,GN模型的非线性噪声功率谱密度理论解析式在预色散的系统中是非常准确、可靠的。同时，表明在没有预色散的系统中，非线性噪声与调制格式有关，但是预色散能够消除调制格式对非线性噪声的影响。
非线性光学 相干通信 光纤非线性效应 克尔效应 光学学报
2014, 34(s2): s219003
Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
A data-aided method of joint frequency offset and chromatic dispersion estimation based on the Chu training sequences is shown in 112 Gb/s polarization-multiplexed (PM) quadrature phase-shift keying and 224 Gb/s PM-16-quadrature amplitude modulation with different pulse-shaping filters, respectively. The proposed method achieves a good accuracy and is verified to be robust to polarization mode dispersion.
060.1660 Coherent communications 060.2330 Fiber optics communications 060.4510 Optical communications Chinese Optics Letters
2014, 12(10): 100606
北京邮电大学 信息与通信工程学院 信息光子学与光通信国家重点实验室, 北京 100876
为了得到高性能的多载波光源，研究了射频信号中不同相位差对光多载波的影响.通过理论分析可得，随着相位差从90°降至0°，光多载波性能会逐渐变差，但是相位差偏与90°相差不大时，性能不会下降太多.实验中通过移相器改变相位差，使相位差为90°,45°,0°，得到循环前IQ调制器的输出光谱，并对比循环后光多载波性能.实验结果显示，相位差为90°时，循环前IQ调制器输出为较好的单边带光谱，循环后输出50条平坦稳定光多载波；相位差为45°时，光多载波质量变差；相位差为0°时，得不到光多载波.因此，射频信号相位差为90°时，光多载波的性能最佳，随着相位差变小，性能下降，但是相位差为45°时，产生的光多载波仍可应用于光通信.
光通信 多载波 循环移频 相偏 稳定平坦 Optical communication Multicarrier RFS Phase deviation Stability and flatness
北京邮电大学信息光子学与光通信国家重点实验室, 北京 100876
非线性相位噪声即高登米勒（G-M）效应是限制相位调制系统传输距离的一个重要因素。系统地研究了G-M效应对单信道速率为40 Gb/s的相干正交频分复用（CO-OFDM）系统的影响。理论分析了在不同的链路参数（入纤功率、跨段距离和色散系数）配置下，放大自发辐射（ASE）噪声沿链路的分布是如何影响系统性能的，并通过搭建CO-OFDM系统的仿真平台，对系统性能进行了仿真研究，比较了两种不同的光纤系统（标准单模光纤系统和非零色散位移光纤系统）中G-M效应的差别。研究发现，G-M效应随着入纤功率的增大而增强。相同的传输长度，跨段距离越小，G-M效应越严重。链路中的累积色散对G-M效应有一定的抵抗作用。
光通信 高登米勒效应 正交频分复用 非线性 光学学报
2012, 32(s1): s106006
Author Affiliations
Abstract
We propose a blind quadrature imbalance (QI) compensation algorithm based on the statistical properties of I and Q signals in a receiver. The algorithm estimates the QI parameters of a receiver by calculating the mean, variance, and correlation coefficient of I and Q components. Then, the estimated imbalance parameters are adopted to compensate for the QI in the receiver. Simulation results show that the Q factor is considerably optimized by the application of the QI compensation algorithm in an 80-Gb/s Pol-Mux coherent optical quadrature phase-shift keying (CO-QPSK) system. Compared with conventional algorithms, the proposed algorithm exhibits better performance when the phase deviation from QI exceeds +-15o.
060.0060 Fiber optics and optical communications 060.1660 Coherent communications 060.2330 Fiber optics communications 070.6020 Continuous optical signal processing Chinese Optics Letters
2012, 10(12): 120601
