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Your search keyword '"Zhai, Jianfeng"' showing total 148 results
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148 results on '"Zhai, Jianfeng"'

4. Multiscale Change Detection Method for Remote Sensing Images Based on Online Learning Framework

Author

Zhang, Jianlong, Zhai, Jianfeng, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, He, Xiaofei, editor, Gao, Xinbo, editor, Zhang, Yanning, editor, Zhou, Zhi-Hua, editor, Liu, Zhi-Yong, editor, Fu, Baochuan, editor, Hu, Fuyuan, editor, and Zhang, Zhancheng, editor

Published
2015
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21. Iterative Learning Control for Digital Predistortion with Undersampled Feedback Signal

Author

Zhuang Xu, Qiang Zhang, Lei Zhang, Chao Yu, Yu Zhiqiang, and Zhai Jianfeng

Subjects
Rate of convergence, Computational complexity theory, Control theory, Computer science, Robustness (computer science), Linearization, RF power amplifier, Iterative learning control, Signal, Predistortion
Abstract

A novel undersampled feedback signal iterative learning control (US-ILC-DPD) technique is proposed to linearize RF power amplifiers (PAs). The proposed method combines the existing iterative learning control (ILC) with the undersampled processing. It can keep the good linearization performance and avoid using high speed ADCs, which are normally expensive and power costly. In addition, the advantages of ILC-DPD, such as low computational complexity and fast convergence rate, are all preserved in this approach. In linearization, an RFPA is excited by a 20-MHz LTE signal, which is sampled at 100, 25 and 12.5MSPS, respectively. Both the proposed approach and the conventional undersampled-DPD based on direct learning architecture (US-DLA) are validated. The experimental results show that, compared with the conventional US-DLA, the US-ILC-DPD has better robustness and linearization performance when the sampling rate is reduced. Meanwhile, the proposed US-ILC-DPD has much lower computational complexity.

Published
2021
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23. The dynamic behavioral model of RF power amplifiers with the modified ANFIS

Author

Zhai, Jianfeng, Zhou, Jianyi, Zhang, Lei, Zhao, Jianing, and Hong, Wei

Subjects
Neural networks -- Models, Power amplifiers -- Models, Electric distortion -- Control, Fuzzy control -- Methods, Neural network, Business, Computers, Electronics, Electronics and electrical industries
Abstract

The adaptive neuro-fuzzy inference system (ANFIS) has been widely used for modeling different kinds of nonlinear systems including RF power amplifiers (PAs). The modified ANFIS (MANFIS) architecture is simpler than that of ANFIS, but with nearly the same performance for modeling nonlinear systems. In this paper, the MANFIS is applied to model RF PAs with memory effects. The simulation and experimental results both in the time and frequency domains show that this model has good modeling accuracy and the characteristics of faster convergence and lower computational complexity compared with the ANFIS model. The normalized mean squared errors of the MANFIS model are slightly lower than those of some other neural network models such as the real-valued time delay neural network, radial basis-function neural network, etc. Finally, the MANFIS model is successfully used in a digital predistortion system, which can provide over 10-dB adjacent channel leakage ratio improvement for three-carrier wideband code division multiple access signals. Index Terms--Adaptive neuro-fuzzy inference system (ANFIS), adjacent channel leakage ratio (ACLR), digital predistortion (DPD), power amplifiers (PAs).

Published
2009

27. A Novel Undersampling Architecture for Wideband Digital Predistortion

Author

Zhai Jianfeng, Yu Zhiqiang, Qiang Zhang, Jie Niu, Chao Yu, and Lei Zhang

Subjects
Undersampling, Linearization, Computer science, Amplifier, Electronic engineering, Demodulation, Wideband, Signal, Predistortion, Power (physics)
Abstract

A novel undersampling architecture is employed to linearize the wideband power amplifiers (PAs) in this paper. The approach samples only I component of the feedback signal with a low sampling rate by means of the random demodulation-based reduced sampling rate (RDRS) method. It has lower complexity compared with some existing digital predistortion (DPD) systems, since a lower speed ADC in the feedback path is required. The least-square algorithm is adopted to extract the DPD coefficients. Experimental results show that the architecture achieves nearly the same linearization performance as the conventional methods and it is highly suitable for the broadband DPD.

Published
2020
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29. The Role of Millimeter-Wave Technologies in 5G/6G Wireless Communications

Author

Hong, Wei, primary, Jiang, Zhi Hao, additional, Yu, Chao, additional, Hou, Debin, additional, Wang, Haiming, additional, Guo, Chong, additional, Hu, Yun, additional, Kuai, Le, additional, Yu, Yingrui, additional, Jiang, Zhengbo, additional, Chen, Zhe, additional, Chen, Jixin, additional, Yu, Zhiqiang, additional, Zhai, Jianfeng, additional, Zhang, Nianzu, additional, Tian, Ling, additional, Wu, Fan, additional, Yang, Guangqi, additional, Hao, Zhang-Cheng, additional, and Zhou, Jian Yi, additional

Published
2021
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32. Design and Implementation of a Full-Digital Beamforming Array With Nonreciprocal Tx/Rx Beam Patterns

Author

Guo, Chong, primary, Hong, Wei, additional, Tian, Ling, additional, Jiang, Zhi Hao, additional, Zhou, Jianyi, additional, Chen, Jixin, additional, Wang, Haiming, additional, Yu, Zhiqiang, additional, Yu, Chao, additional, Zhai, Jianfeng, additional, Zhang, Nianzu, additional, Hou, Debin, additional, Yang, Guangqi, additional, Chen, Zhe, additional, Wu, Fan, additional, Yu, Yingrui, additional, Shu, Chang, additional, Huang, Fei, additional, Zhu, Xiao-Wei, additional, and Hao, Zhang-Cheng, additional

Published
2020
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37. A Band-Limited Magnitude-Selective Affine Function-Based Model for Digital Predistortion of 5G Broadband Power Amplifiers.

Author

Zhai, Jianfeng, Wang, Kai, Xu, Zhuang, Zhang, Qiang, Liu, Jiawen, Zhou, Jianyi, Yu, Zhiqiang, and Yu, Chao

Abstract

A band-limited magnitude-selective affine (MSA) function-based model is proposed for digital predistortion (DPD) of broadband power amplifiers (PAs) in 5G millimeter-wave frequency band. The new model is derived from the band-limited canonical piecewise linear function-based model by employing MSA functions, which can obviously reduce the number of multiplication operations and the model complexity. Experimental results show that the proposed model gives better normalized mean square error and DPD performance in comparison with some existing models when a broadband PA is excited by a 5G new radio (NR) signal of 400-MHz bandwidth at 28-GHz band. [ABSTRACT FROM AUTHOR]

Published
2022
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38. An automatic error compensation method for the feedback loop in adaptive DPD systems

Author

Zhao, Jianing, Zhou, Jianyi, Zhai, Jianfeng, Liang, Xiao, and Hong, Wei

Subjects
Baseband -- Research, Power amplifiers -- Research, Feedback loops (Systems theory) -- Research, Error-correcting codes -- Research, Business, Electronics and electrical industries, Engineering and manufacturing industries, Telecommunications industry
Abstract

Error items of modulation and demodulation in the feedback loop in baseband digital predistortion systems are analyzed. A compensation and correction algorithm is developed to correct these errors.

Published
2008

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