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AN IMPROVED SMM ALGORITHM

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Journal of Electronics(china) 1999年第1期16卷 93-96页

作者： Chen Yun(uest of china, chengdu 610054)

A new fast algorithm to compute modular exponentiation for very large integers is proposed in this paper, which is an improvement of the fast RSA algorithm based on Symmetry of Modular Multiplication(SMM). The SMM algorithm obtains the speed improvement by conditional substitution on every basic operation to decrease the absolute value of product and the operation numbers of modular reductions. The proposed algorithm can get faster operation speed by decreasing the numbers of basic operations. Compared to conventional binary representation, a speed improvement of approximately 47.5% would be expected using the proposed algorithm.

关键词： Cryptology Public key cryptosystem RSA Modular exponentiation

SECURE GROUP COMMUNICATIONS FOR LARGE DYNAMIC MULTICAST GROUP

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Journal of Electronics(china) 2003年第4期20卷 265-273页

作者： Liu Jing Zhou Mingtian (College of Computer Science and Engineering, uest of china, chengdu 610054) College of Computer Science and Engineering UEST of China Chengdu 610054

As the major problem in multicast security, the group key management has been the focus of research But few results are satisfactory. In this paper, the problems of group key management and access control for large dynamic multicast group have been researched and a solution based on SubGroup Secure Controllers (SGSCs) is presented, which solves many problems in IOLUS system and WGL scheme.

关键词： Multicast security Group communication Group key management Access control Secret key tree

SUBSPACE METHOD FOR BLIND IDENTIFICATION OF CDMA TIME-VARYING CHANNELS

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Journal of Electronics(china) 2002年第1期19卷 61-67页

作者： Liu Yulin Peng Qicong (School of Communication and Information Engineering, uest of china, chengdu 610054) School of Communication and Information Engineering UEST of China Chengdu 610054

A new blind method is proposed for identification of CDMA Time-Varying (TV)channels in this paper. By representing the TV channel's impulse responses in the delay-Doppler spread domain, the discrete-time canonical model of CDMA-TV systems is developed and a subspace method to identify blindly the Time-Invariant (TI) coordinates is proposed. Unlike existing basis expansion methods, this new algorithm does not require .estimation of the base frequencies, neither need the assumption of linearly varying delays across symbols. The algorithm offers definite explanation of the expansion coordinates. Simulation demonstrates the effectiveness of the algorithm.

关键词： CDMA Time-varying channels Blind identification Delay-Doppler spread domain Subspace method

IMPLEMENTING SECURITY FOR ACTIVE NETWORKS IN INTERNET

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Journal of Electronics(china) 2003年第4期20卷 305-308页

作者： Tang Yin Wang Weiran (College of Electronic Engineering, uest of china, chengdu 610054) College of Electronic Engineering UEST of China Chengdu 610054

Active networks is primarily a Defense Advanced Research Projects Agency(DARPA)-funded project focusing on the research of mechanisms, applications, and operating systems to develop a reconfigurable network infrastructure. This letter proposes an Secure Active Tracing System (SATS) to implementing security for active networking in Internet. Unlike currently existing schemes, SATS reduces the computational overloads by executing the filtering operation on selected packet streams only when needed.

关键词： Active networks Security Distributed Denial of Service (DDoS) Active network Backbone(ABone) Active Network Transport System(ANTS) Active Signaling Protocol (ASP)

STABILITY ANALYSIS OF BIDIRECTIONAL ASSOCIATIVE MEMORY WITH AXONAL SIGNAL TRANSMISSION DELAYS

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Journal of Electronics(china) 1997年第4期14卷 345-351页

作者： Liao Xiaofeng Liu Guangyuan Yu Juebang (Dept. of Optoelectronic Technology uest of china, chengdu 610054)

In this paper, conditions for the existence of equilibrium points and global stability are emphatically discussed for Bidirectional Associative Memory(BAM) models with axonal signal transmission delays, and the discussed methods are more general. The correctness of obtained conclusions is verified by use of some examples. The obtained results have primary significance in the design and application of BAM.

关键词： Axonal signal transmission delays Neural networks of BAM Existence of equilibrium point Global stability

FINDING THE OPTIMAL LENGTH OF DATA FRAME IN PLC COMPUTER NETWORK

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Journal of Electronics(china) 2003年第2期20卷 154-160页

作者： Huang Ronghui Zhou Mingtian She Kun (College of Computer Science & Eng., uest of china, chengdu 610054) College of Computer Science & Eng. UEST of China Chengdu610054

The length of data frame is an important parameter in Medium Access Control(MAC) layer protocol. A method of finding the optimal length of data frame when impulsive disturbance is involved in PowerLine Communications (PLC) is proposed. Having analyzed the characteristics of impulsive disturbance in powerline and the collision mechanism between the disturbance and data frame, this letter gives the function of the network channel utilization with the length of data frame in MAC layer and the impulsive disturbance. Our stochastic process simulation shows that it is feasible to get the optimal length of data frame.

关键词： Medium Access Control (MAC) PowerLine Communications(PLC) Computer network

THE SOLUTION TO AN AMBIGUITY PROBLEM WITH NOISE PROTECTION IN NUMBER SYSTEM

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Journal of Electronics(china) 2000年第2期17卷 123-131页

作者： Lin Yunsong Huang Yong Xiao Xianci (College of Electronic Engineering, uest of china, chengdu 610054)

The relationship between the discrete Fourier transform (DFT) and the symmetrical/asymmetrical number system (SNS/ANS) is introduced in this paper. And the influence of noise upon the solution to the ambiguity problem in number system is also discussed. The principle of noise insensitive solution to the ambiguity in ANS system is extended to SNS system. The unambiguous bandwidth equations with noise protection in SNS are presented, based on which a real time noise insensitive algorithm in SNS for resolving undersampling ambiguous frequency is proposed.

关键词： Unambiguous bandwidth Residue error Undersampling

ACCURATE DETECTION OF HIGH-SPEED MULTI-TARGET VIDEO SEQUENCES MOTION REGIONS BASED ON RECONSTRUCTED BACKGROUND DIFFERENCE

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Journal of Electronics(china) 2001年第1期18卷 1-7页

作者： Zhang Wentao Li Xiaofeng Li Zaiming (Inst. of Communication and Information, uest of china, chengdu 610054) Inst. of Communication and Information UEST of China Chengdu 610054

The paper first discusses shortcomings of classical adjacent-frame difference. Sec ondly, based on the image energy and high order statistic(HOS) theory, background reconstruction constraints are setup. Under the help of block-processing technology, background is reconstructed quickly. Finally, background difference is used to detect motion regions instead of adjacent frame difference. The DSP based platform tests indicate the background can be recovered losslessly in about one second, and moving regions are not influenced by moving target speeds. The algorithm has important usage both in theory and applications.

关键词： Motion detection Background reconstruction Image energy HOS High-Speed target Block processing

INSTANTANEOUS DOPPLER FREQUENCY FOR SQUINT SAR IMAGING

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Journal of Electronics(china) 2003年第5期20卷 337-343页

作者： Liu Guangyan Huang Shunji (Dept. of Electron. Eng., uest of china, chengdu 610054) Dept. of Electron. Eng. UEST of China Chengdu 610054

Instantaneous Doppler frequency for squint SAR imaging has been found with ChirpScaling Algorithm (CSA). Because the azimuth sample is not perpendicular to the range sample,the range signal must impact on the azimuth signal in the squint SAR data processing, andthe different slant range targets have different Doppler frequencies. From the mathematicalmodel of SAR echo signal, this paper carefully analyzes the instantaneous azimuth frequency, theinstantaneous Doppler frequency component of the azimuth frequency and the impact of rangechirp on azimuth frequency, which explains that Doppler frequency should be properly selected forcorrect SAR imaging in the squint SAR. The results of point target simulation experiments showthat the way is reasonable for the squint SAR and can effectively complete range compressionand azimuth focusing, and improve images' quality.

关键词： PRF Doppler frequency Chirp scaling algorithm Range chirp rate SAR