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• • 2002, Vol. 25 No. 1 Published date:10 January 2002 Last issue Next issue

  Review

  • Overview of Dyadic Theory
  • YANG Yi-xian, HU Zheng-ming, XU Cheng-qian
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 1-16.
  • Abstract ( 282 )     HTML     　　
  • A brief and systematic introduction on the theory ofdyadic is presented. Dyadic operations, dyadic groups, dyadic block designs, dyadic calculus, and analysis and synthesis of dyadic signals are the concentrations.
  • References | Supplementary Material | Related Articles

  Original articles

  • Digital Watermark Sharing Based onChinese Remainder Theorem
  • LIU Jun, LUO Shou-shan, WU Qiu-xin,
    NIU Xin-xin, YANG Yi-xian
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 17-21.
  • Abstract ( 242 )     HTML     　　
  • A digital watermark sharing algorithm based on Chinese remainder theorem is proposed. This algorithm is mainly used for the copyrightprotection for the static pictures. The idea of the secret sharing to the digital watermark is introduced, and the watermark recovering based on incomplete content is realized. The algorithm has some good properties. It has a good hiding effect. The difference between the original and the watermarked pictures can notbe perceived by eyes. The original picture is not needed in the recover process.The watermark can still be recovered even though the image was damaged. The algorithm has a good security. The recover process is protected by password. Anyonewho don't know the password can't recover the watermark.
  • References | Supplementary Material | Related Articles

  • FPGA Implementation of Turbo Decoder for WCDMA System:#br# High Efficient Structure for Log-MAP Turbo Decoder
  • JIANG Jun, BAI Chun-long, ZHANG Ping, HU Jian-dong
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 22-26.
  • Abstract ( 309 )     HTML     　　
  • Based on the intensive research on the decoding algorithm of the turbo codes, a turbo code decoder with a high efficient structure is implemented with FPGA, and have good performence when used in WCDMA system.
  • References | Supplementary Material | Related Articles

  • The Traversing of Genetic Algorithms Based on #br# Mutation of Column in Population
  • MENG Xiang-wu, ZHANG Yu-jie
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 27-29.
  • Abstract ( 247 )     HTML     　　
  • The reason for premature convergence of genetic algorithms is analyzed, and then an genetic algorithms based on mutation of column in population is presented, the properties of crossover and mutation in this genetic algorithms are analyzed, the traversing property of this genetic algorithmsis proved. The new algorithm copes with the limitations of genetic algorithms,can avoid premature convergence by mutation of column in population, and find optimal solutions.
  • References | Supplementary Material | Related Articles

  • Effective Orthogonal Constant Modulus Algorithm
  • GUO Yan, FANG Da-gang, LIANG Chang-hong
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 30-33.
  • Abstract ( 266 )     HTML     　　
  • The number of desired signals is detected by using singular value decomposition. And the array input is transformed into the signal subspace. Orthogonality is derived for the weight vectors in multiple beamforming on this subspace. According to which, an orthogonal constant modulus algorithm is proposed by introducing the orthonormalization procedure into the static least square constant modulus algorithm. The simulation results via computer confirm its validity.
  • References | Supplementary Material | Related Articles

  • Study of Balance Problem for a Three-Arm Space Robot#br# during Its Manipulation
  • SUN Han-xu, JI Luo-shuan, XU Yang-sheng
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 34-38.
  • Abstract ( 277 )     HTML     　　
  • The balance problem of athree-arm space robot has been discussed during its manipulation. The first arm of the space robot is used to keep connection with the spacecraft (shuttle orspace station), the second arm to balances the whole system, and the third arm to manipulate a job. The linear momentum and angular momentum equations and an optimization function have been advanced. An optimization solution of the angles and the angular velocities of those joints of the second arm (the balance arm) according to conservation of the linear momentum and angle momentum of all systemhave been gotten respectively. One example of a simple three-arm space robot onan air-bearing table has been simulated and the results simulated have been given out with two pictures.
  • References | Supplementary Material | Related Articles

  • Analysis of Error Detection Codes in Optical Transport Networks
  • LI Han, WANG Jian-quan, ZHANG Jie, GU Wan-yi
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 39-42.
  • Abstract ( 259 )     HTML     　　
  • Based on burst error model, the mathematical expressions for the probability of occurrence of a block error and the probability of detecting a block error, as well as the detection efficiency. Analysesand simulations to determine the maximum BER that can be detected (i.e., thesaturation BER) and the minimum detection efficiency are given. Conclusions aredrawn as follows: 2×BIP-4 EDC can satisfy the performance monitoring requirement for each tandem connection. When real-time BER measurement estimation is not required, 8×BIP-1 EDC is acceptable and 6 dB extra saturation BER is provided.
  • References | Supplementary Material | Related Articles

  • The Design Method of High-Speed Backplane with #br# Nonuniformly Distributed Loads
  • YE Dong, LU Ying-hua, DING Wei
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 43-47.
  • Abstract ( 222 )     HTML     　　
  • A approximation in subsection is proposed to analyzethe high-speed signal in backplane design with nonuniformly distributed loads,which is verified by the implementation of UTOPIA Level 2 Bus.
  • References | Supplementary Material | Related Articles

  • Capacity Analysis of Mobile Communication Systems #br# Using Smart Antenna
  • ZHU Ming-hua, LIU Yuan-an
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 48-52.
  • Abstract ( 218 )     HTML     　　
  • One of the effective means of increasing capacity ofmobile communication systems is the use of smart antenna at base stations. The principles of increasing capacity of GSM systems and CDMA systems using smart antenna at base stations are investigated. Estimations of the capacity increase for the two systems are also carried out. The results show that the capacity of the two systems can be increasedN-folds(N＞1). CDMA systems havethe larger capacity increase than GSM systems.
  • References | Supplementary Material | Related Articles

  • Two RTP Based Models of MPEG Video Source and #br# Their Comparison
  • TAO Meng-hua, HUANG Xiao-jian, SHEN Shu-qun
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 53-57.
  • Abstract ( 230 )     HTML     　　
  • As to the transportation of real-time multimediaon IP network, two models of MPEG video source based on RTP are presented for the first time. One considers the relation between I frame and P, B frames, and Gamma distribution is used to model I frame,while P,B frames are modeled with compound regressive model. The other uses Gamma distribution to model I,P,B framesrespectively. Simulation indicates the validity of the two models, and comparison is made between them.
  • References | Supplementary Material | Related Articles

  • Transformation of Function Limit Form#br# and Some Applications
  • ZHAO Qisong
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 58-63.
  • Abstract ( 229 )     HTML     　　
  • The concept of limit form with function is given, then the transformation formulas of limit form and some applications are discussed.
  • References | Supplementary Material | Related Articles

  • Finite Element Analysis of Optical Waveguides #br# in Asymmetry Fiber Couplers
  • WU Lei, ZHENG Yuan, QI Jiang, PU Hong-tu, CHEN Shu-qiang
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 64-67.
  • Abstract ( 376 )     HTML     　　
  • The electromagnetic field characteristics of opticalwaveguides in asymmetry fiber couplers are investigated by a finite element method. An adaptive-size triangular mesh is employed to obtain the propagation constants of the first four modes in different constructions. Numerical result shows that the propagation constants of even and odd modes are obviously affected by the radius ratio of the two fibers composing the coupler. In comparison with odd mode, the propagation constant of even mode is insensitive to fusion degree of fibers.
  • References | Supplementary Material | Related Articles

  • A New Channel Estimation Algorithm for Time-Multiplexed#br# Pilot Channel
  • XU Xia-yan, LIN Jia-ru, WU Wei-ling
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 68-72.
  • Abstract ( 245 )     HTML     　　
  • A new channel estimation algorithm based on time-multiplexed pilot channel is proposed. By weighted LSM fitting over multi-slot, the complex channel coefficients are estimated. Simulation results show that thenew algorithm can track the variation of multipath channel better than several other algorithms, such as linear interpolation. The performance of Rake receiverapplying the new channel estimation algorithm is basically stable under a widerrange of Doppler frequency.
  • References | Supplementary Material | Related Articles

  • Blind Identification and Multiuser Detection Based #br# on Subspace in Antenna Arrays Systems
  • YAN Yu-ping, LIU Ze-min
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 73-78.
  • Abstract ( 247 )     HTML     　　
  • A blind identification process of each user' multipath channel using a subspace method for antenna arrays CDMA systems is presented.It is shown that based on the identified channel and combined with the knowledgeof the desired user' spreading sequence, multiuser detector can be constructedin closed form, at almost no extra computational cost. Because the computing of some high-dimension matrices has been avoided directly, the computation complexity becomes lower. By using antenna arrays, the proposed method can be applied to overload systems, where the number of users may exceed the processing gain.
  • References | Supplementary Material | Related Articles

  • Information Hiding Technology of Voice #br# Encryption Communication
  • YUE Jun-qiao, NIU Xin-xin, YANG Yi-xian
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 79-82.
  • Abstract ( 283 )     HTML     　　
  • The basis of the theoryand the application of environment of the voice-substitution phone(VSP) is introduced. The paper focuses on the principle and core of the VSP. In addition, its performance is described.
  • References | Supplementary Material | Related Articles

  • Design of a Data Processing Modelfor the Local Switch Network
  • FAN Chun-xiao, XU Mu-hong, LIU Jie
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 83-86.
  • Abstract ( 232 )     HTML     　　
  • A universal data processing model of fault alarms forlocal switching network has been analysed and realized. It solves the problem of processing data of multi-products and multi-model switch in uniform format.
  • References | Supplementary Material | Related Articles

  • Design of Two-Band PR FIR Filter Banks with Low Delay
  • LI Dong-ping, ZHAO Er-yuan, YUE Guang-xin
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 87-90.
  • Abstract ( 226 )     HTML     　　
  • Based on the lifting scheme, a new design algorithm is proposed for two-band PR FIR filter banks with low delay.In this new method, the lifting functions are selected as non-linear phase functions and the error is defined as the difference between the ideal frequency response and the actual response of the liting functions. During the design of lifting functions, the jointed approximation between real part and imaginary part is exploited.
  • References | Supplementary Material | Related Articles

  • Analysis for Security of the Border Gateway Protocol and#br# Discussion about a Security Mechanism for the BGP
  • WANG Hang, XU Sai-hong, MA Yue, GAO Xi-wu
  • Journal of Beijing University of Posts and Telecommunications. 2002, 25(1): 91-94.
  • Abstract ( 278 )     HTML     　　
  • The security of the BGP is analyzed and a security mechanism is discussed. Some modifications to the protocol message are presented in order to minimize or eliminate the most significant threats. The mechanism is capable of securing complete path information in near constant space.
  • References | Supplementary Material | Related Articles