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192 results on '"Peng, Kewu"'

1. Multiuser Diversity Gain from Superposition of Infinite Users over Block-Fading MAC

Author

Zhang, Yushu, Peng, Kewu, Song, Jian, and Chen, Shuang

Subjects
Computer Science - Information Theory
Abstract

In uplink block-fading multiple access channel (BF-MAC), the advantage of multiuser diversity (MUD) can be taken to achieve higher system throughput. In this letter, with rate constraints for all users and only channel state information available at the receiver assumed, we demonstrate that non-orthogonal multiple access (NOMA) outperforms the counterpart of orthogonal multiple access (OMA) via exploiting the MUD from the superposition of multiple users. The MUD gain achieved by NOMA compared with OMA is quantitatively analyzed for finite users, and the closed-form upper bound of MUD gain from the superposition of infinite users is also derived. Numerical results show that the potential MUD gain from superposition of infinite users can be well approached with limited superposed users, which indicates that multiple access schemes with limited superposed users can provide a good tradeoff between system performance and decoding complexity., Comment: 5 pages, 5 figures

Published
2016

2. Offset Generation and Interlayer Network Architecture for 5GNR LDPC Parallel Layered Decoder with Variable Lifting Factor Support

Author

Krylov, Aleksei, Rashich, Andrey, Zhang, Chao, Peng, Kewu, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Woeginger, Gerhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Galinina, Olga, editor, Andreev, Sergey, editor, Balandin, Sergey, editor, and Koucheryavy, Yevgeni, editor

Published
2020
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8. Low-Rate LDPC Code Design for DTMB-A

Author

He, Zhitong, Peng, Kewu, Zhang, Chao, and Song, Jian

Abstract

Digital terrestrial television multimedia broadcasting-advanced (DTMB-A) proposed by China is served as a 2nd generation digital terrestrial television broadcasting (DTTB) standard with advanced forward error correction coding schemes. Nevertheless, to adapt low signal-to-noise ratio (SNR) scenarios such as in cloud transmission systems, LDPC codes with low rates are required for DTMB-A. In this paper, the new design of low-rate DTMB-A LDPC codes is presented systematically. Specifically, a rate-compatible Raptor-Like structure of low-rate DTMB-A LDPC codes is presented, which supports multiple low code rates with constant code length. Then a new construction method is proposed for low-rate DTMB-A LDPC codes, where progressive block extension is employed and the minimum distance is majorly optimized such that the minimum distance increases after each block extension. Finally, the performance of the constructed DTMB-A LDPC codes with two low code rates of 1/3 and 1/4 are simulated and compared with ATSC 3.0 LDPC codes, which demonstrates the effectiveness of our design.

Published
2024
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15. Field Trials of UHDTV Broadcasting over DTMB-A System

Author

Song, Jian, primary, Zhang, Chao, additional, Peng, Kewu, additional, Wang, Jintao, additional, Pan, Changyong, additional, Yang, Fang, additional, Wang, Jun, additional, Yang, Hui, additional, Xue, Yonglin, additional, Zhang, Yu, additional, and Yang, Zhixing, additional

Published
2021
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17. High-throughput QC-LDPC decoders

Author

Jiang, Nan, Peng, Kewu, Song, Jian, Pan, Chanyong, and Yang, Zhixing

Subjects
Decoders -- Analysis, Business, Electronics, Mass communications
Abstract

High-throughput design approaches for quasi-cyclic (QC) low-density parity-check (LDPC) decoders are presented in this paper. Three novel schemes for the horizontal process in min-sum algorithm and its revisions are derived to reduce design and implementation complexity. The schemes can be directly applied for variant QC codes and easily pipelined to increase the operating frequency of the decoder. Some improvements of the semi-parallel architecture are proposed to enhance throughput performance and hardware efficiency. Employing the proposed approaches, QC-LDPC decoders for Chinese Digital Television Terrestrial Broadcasting (DTTB) standard are implemented using field programmable gate array (FPGA). As shown in the results, the proposed approaches can substantially improve the throughput performance, as well as the throughput-and-hardware tradeoff, of decoders with semi-parallel architecture. Index Terms--LDPC, LDPC decoder, min-sum algorithm, pipeline, QC-LDPC, soft-decision decoder, throughput.

Published
2009

20. Robust frame synchronization for Chinese DTTB system

Author

Tang, Shigang, Peng, Kewu, Gong, Ke, Song, Jian, Pan, Changyong, and Yang, Zhixing

Subjects
Algorithms -- Methods, Television broadcasting -- Methods, Signal processing -- Methods, Algorithm, Digital signal processor, Business, Electronics, Mass communications
Abstract

Digital terrestrial multimedia/television broadcasting (DTMB), which is the recently released Chinese digital television terrestrial broadcasting (DTTB) standard, uses guard intervals padded with known pseudo-noise (PN) sequences for multi-carrier or single-carrier block transmission. Well designed synchronization algorithms are a prerequisite for achieving high-quality multimedia transmission. In this paper, a novel frame synchronization technique, which is robust to carrier frequency offset (CFO), is proposed for DTMB systems. This technique is derived through segmenting the local PN sequence into M contiguous blocks and performing multiple cross-correlations with the received signal. The metric for peak detection is defined as the non-coherent summation of the M cross-correlation magnitude outputs. Moreover, a low-complexity frame synchronizer based on segment-based full correlation for PN420 mode in DTMB system is proposed. It is shown through computer simulation that the proposed techniques generally outperform the conventional ones when CFO occurs, over both AWGN and frequency-selective fading channels. For a DTMB system using PN420 mode, the maximal allowed CFO to keep system still working normally of our proposed schemes are more than 3 times larger than that of the conventional method. Index Terms--Carrier frequency offset(CFO), digital terrestrial multimedia broadcasting (DTMB), frame synchronization.

Published
2008

21. Embedded image compression based on wavelet pixel classification and sorting

Author

Peng, Kewu and Kieffer, John C.

Subjects
Data compression -- Methods, Data compression -- Analysis, Signal processing -- Analysis, Wavelet analysis, Digital signal processor, Business, Computers, Electronics, Electronics and electrical industries
Abstract

The concept of pixel classification and sorting are used to describe the modeling and ordering of embedded image compression in wavelet domain. In pixel classification and sorting (PCAS), pixels to be coded are classified into several quantified contexts based on a large context template and sorted based on their estimated significance probabilities.

Published
2004

22. Performance Analysis and Power Allocation for Spatial Modulation-Aided MIMO-LDM With Finite Alphabet Inputs

Author

Zhang, Shunlei, Peng, Kewu, and Song, Jian

Abstract

In this paper, we study a spatial modulation (SM) aided multiple-input multiple-output (MIMO) layered division multiplexing (LDM) system for broadcast/multicast service delivery in future broadcast/multicast systems. Comprehensive performance analysis and the injection level (IL) optimization are investigated for the SM-aided MIMO-LDM system over correlated Rayleigh fading channels. First, the symbol detection pairwise error probability (PEP) and the average symbol error rate (SER) union bound under joint maximum-likelihood (ML) detection are derived. Second, the spectral efficiency (SE) of the SM-aided MIMO-LDM system with finite alphabet inputs is analyzed. Since the theoretical SE lacks closed-form expression and involves prohibitive computational complexity, we then derive the closed-form lower bounds and tight approximations for the theoretical SE, in which the computational complexity is relieved by several orders of magnitude compared to direct calculation of the theoretical SE. Third, based on the SE analysis, a weighted sum (WS) SE maximization problem with quality of service (QoS) constraints is formulated to optimize IL for the SM-aided MIMO-LDM system. We first demonstrate that WS SE is a unimodal function of IL, and then develop an efficient golden section search (GSS) based algorithm. Simulation results are provided to validate the theoretical analysis. It is shown that our derived SER union bound well matches the simulated SER in the high SNR region. The tightness of the derived closed-form lower bounds and approximations for theoretical SE and the effectiveness of the developed IL optimization algorithm are also verified by simulation results.

Published
2023
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23. Review on 5G NR LDPC Code: Recommendations for DTTB System

Author

Li, Fengshuang, primary, Zhang, Chao, additional, Peng, Kewu, additional, Krylov, Aleksei E., additional, Katyushnyj, Aleksandr A., additional, Rashich, Andrey V., additional, Tkachenko, Dmitry A., additional, Makarov, Sergey B., additional, and Song, Jian, additional

Published
2021
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32. Key Technologies and Measurements for DTMB-A System

Author

Song, Jian, primary, Zhang, Chao, additional, Peng, Kewu, additional, Wang, Jintao, additional, Pan, Changyong, additional, Yang, Fang, additional, Wang, Jun, additional, Yang, Hui, additional, Xue, Yonglin, additional, Zhang, Yu, additional, and Yang, Zhixing, additional

Published
2019
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49. Study on Mechanical Properties and Fracture Mechanisms of B4 C-CeB6/A1 Composites

Author

Gan-feng Tu, Ning Fuhu, Peng Kewu, Wenyuan Wu, and Xu Jingyu

Subjects
Flexibility (anatomy), Materials science, chemistry.chemical_element, General Chemistry, Boron carbide, chemistry.chemical_compound, Fracture toughness, medicine.anatomical_structure, chemistry, Geochemistry and Petrology, Aluminium, medicine, Fracture (geology), Composite material, Ductility, Porosity
Abstract

B 4 C-CeB 6 /Al composites were first fabricated by pressureless infiltration technology. The mechanical properties of B 4 C-CeB 6 /Al composites were tested. The results show that the density, the flexibility strength and the fracture toughness of B 4 C-CeB 6 /Al composites were greatly improved compared with those of monolithic boron carbide, but the hardness of it decreased. The analysis of B 4 C-CeB 6 /Al composites by using the fracture scanning electric microscope and the back-scattering equipment showed that, the fracture way of B 4 C-CeB 6 /Al composites was intercrystalline rupture. The flexibility strength and the fracture toughness of B 4 C-CeB 6 /Al composites were greatly improved for two major reasons. Firstly the flexibility strength and the fracture toughness of B 4 C-CeB 6 porous perform were improved because for the CeB 6 existing. Secondly the ductility of aluminum was manifested in B 4 C-CeB 6 /Al composites.

Published
2007
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