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2000 Vol. 22, No. 6
Display Method:
2000, 22(6): 881-889.
Abstract:
How to improve the quality of service in internet networks is a hot topic at present. This paper presents an implementation algorithm-Random Early Detection with In and Out(RIO) to support differentiated services in multi-protocol label switching-based ATM switches. The throughput, fairness and delay of this algorithm are studied to show that this algorithm can support differentiated services efficiently.
How to improve the quality of service in internet networks is a hot topic at present. This paper presents an implementation algorithm-Random Early Detection with In and Out(RIO) to support differentiated services in multi-protocol label switching-based ATM switches. The throughput, fairness and delay of this algorithm are studied to show that this algorithm can support differentiated services efficiently.
2000, 22(6): 890-897.
Abstract:
To multi-station(multiqueue) cyclic service system, this paper advances a grade compound new strategy of a development adjust service quantity to fit the station load unbalance system. This paper discusses mainly about:(1) Introduce new strategy;(2) The features of new strategy system line up service model; (3) The queue status transition regularity of limited capacity new strategy system;(4) The algorithm of queue status transition rate; (5) The irregular algorithm of queue status rate.
To multi-station(multiqueue) cyclic service system, this paper advances a grade compound new strategy of a development adjust service quantity to fit the station load unbalance system. This paper discusses mainly about:(1) Introduce new strategy;(2) The features of new strategy system line up service model; (3) The queue status transition regularity of limited capacity new strategy system;(4) The algorithm of queue status transition rate; (5) The irregular algorithm of queue status rate.
2000, 22(6): 898-905.
Abstract:
Power control is of paramount important to combat the near-far problem and achieve high system capacity in CDMA cellular system. In this paper, a Modified Neural Network (MNN) based power controller is proposed to smoothen out the fast fading and keep the received signal power from each user constant at the base station. Simulation results show that MNN power controller achieves better control performance and system capacity than fixedstep controller due to the inherent ability of MNN to identify the fast time-varying characteristic of inverse channel.
Power control is of paramount important to combat the near-far problem and achieve high system capacity in CDMA cellular system. In this paper, a Modified Neural Network (MNN) based power controller is proposed to smoothen out the fast fading and keep the received signal power from each user constant at the base station. Simulation results show that MNN power controller achieves better control performance and system capacity than fixedstep controller due to the inherent ability of MNN to identify the fast time-varying characteristic of inverse channel.
2000, 22(6): 906-913.
Abstract:
This paper proposes a space-time pre-RAKE system for the downlink in TDD/DS-CDMA. The system realizes space-selective transmission and temporal pre-RAKE. Performance analysis in single- and multi-user environment is presented and the relation between system performance and channel parameters (angle spread, Doppler frequency and burst frame size) is discussed.
This paper proposes a space-time pre-RAKE system for the downlink in TDD/DS-CDMA. The system realizes space-selective transmission and temporal pre-RAKE. Performance analysis in single- and multi-user environment is presented and the relation between system performance and channel parameters (angle spread, Doppler frequency and burst frame size) is discussed.
2000, 22(6): 914-920.
Abstract:
Regional mobile satellite communication systems are very important for developing countries, especially for China that lacks the basic communication methods in her large rural areas. Adopting Medium Earth Orbit (MEO) constellation is an effective way for this situation Time-dependent constellation for the regional mobile satellite communication systems is proposed in this paper. The constellation can provide excellent coverage performance for special territory, and the system service provided by the constellation can be time-limited and nontime-limited. The constellation schemes (time-limited and non-time-limited) of the economical mobile satellite communication system for China designed with this method are proposed in this paper, and they also can provide excellent service for United States.
Regional mobile satellite communication systems are very important for developing countries, especially for China that lacks the basic communication methods in her large rural areas. Adopting Medium Earth Orbit (MEO) constellation is an effective way for this situation Time-dependent constellation for the regional mobile satellite communication systems is proposed in this paper. The constellation can provide excellent coverage performance for special territory, and the system service provided by the constellation can be time-limited and nontime-limited. The constellation schemes (time-limited and non-time-limited) of the economical mobile satellite communication system for China designed with this method are proposed in this paper, and they also can provide excellent service for United States.
2000, 22(6): 921-928.
Abstract:
The problem of identifying the parameters of the nonminimum phase FIR system from the cumulants of noisy output samples is addressed. A novel method by using higher-order cumulants is proposed with the following advantages. (1) Flexibility: the method employs two arbitrary adjacent order cumulants of output.(2) Linearity: the formulation in the method is linear with respect to the unknowns, unlike the existing cumulant-based algorithms. The post-processing is thus avoided.
The problem of identifying the parameters of the nonminimum phase FIR system from the cumulants of noisy output samples is addressed. A novel method by using higher-order cumulants is proposed with the following advantages. (1) Flexibility: the method employs two arbitrary adjacent order cumulants of output.(2) Linearity: the formulation in the method is linear with respect to the unknowns, unlike the existing cumulant-based algorithms. The post-processing is thus avoided.
2000, 22(6): 929-936.
Abstract:
A variable bit-rate audio coding algorithm controlled by desired audio quality is designed. This algorithm can be used to minimize the bit-rate of audio coding at a given level of audio quality.
A variable bit-rate audio coding algorithm controlled by desired audio quality is designed. This algorithm can be used to minimize the bit-rate of audio coding at a given level of audio quality.
2000, 22(6): 937-943.
Abstract:
Sub-images contain different information when the original image decomposed with wavelet. By modifying the larger wavelet coefficients of middle-high frequency range detail subimages with pseudo-random sequence of real numbers, the paper proposes a scheme for static gray image watermarking embedding and detection based on wavelet multiresolution transform. The experimental results show that the embedding watermarking is robust enough and the watermarking detection is only relevant to some detail sub-images, it simplifies and accelerates the algorithm.
Sub-images contain different information when the original image decomposed with wavelet. By modifying the larger wavelet coefficients of middle-high frequency range detail subimages with pseudo-random sequence of real numbers, the paper proposes a scheme for static gray image watermarking embedding and detection based on wavelet multiresolution transform. The experimental results show that the embedding watermarking is robust enough and the watermarking detection is only relevant to some detail sub-images, it simplifies and accelerates the algorithm.
2000, 22(6): 944-950.
Abstract:
In this paper, a constituting method of binary codes of constant weight and distance with parameters (n, 6, m)(m 6) is given. The basic structure form of this kind of codes is discussed and the subset block of basic unit which can be used to constitute this kind of codes is designed. The constituting rule and realization result are analysed. Finally, the numbers of permutations and the properties of error-detecting codes are discussed.
In this paper, a constituting method of binary codes of constant weight and distance with parameters (n, 6, m)(m 6) is given. The basic structure form of this kind of codes is discussed and the subset block of basic unit which can be used to constitute this kind of codes is designed. The constituting rule and realization result are analysed. Finally, the numbers of permutations and the properties of error-detecting codes are discussed.
2000, 22(6): 951-958.
Abstract:
Each submodel of a half plane compound Gauss-Markov model, which is identified by a line process, is suitable for describing stationary or nonstationary DVF(displacement vector field); In order to determine the a priori distribution of these submodels, a half plane Markov random field model is utilized to describe the distribution of the line process. Thus, a recursive and adaptive DVF estimation algorithm based on multiple model approach is developed in this paper.
Each submodel of a half plane compound Gauss-Markov model, which is identified by a line process, is suitable for describing stationary or nonstationary DVF(displacement vector field); In order to determine the a priori distribution of these submodels, a half plane Markov random field model is utilized to describe the distribution of the line process. Thus, a recursive and adaptive DVF estimation algorithm based on multiple model approach is developed in this paper.
2000, 22(6): 959-964.
Abstract:
A fuzzy controller based on the distance between two fuzzy sets is proposed in this article. First, a definition of distance between two fuzzy sets is proposed. This definition is different from traditional ones for its dependent on the cardinal numbers and centroids of the two fuzzy sets. Then the method is used in designing a fuzzy controller. It is also pointed out that the fuzzy controller implemented through this way can approximate any continuous real function. The fuzzy controller proposed is able to handle the problem in the case that the input universe is not covered completely with the rule base.
A fuzzy controller based on the distance between two fuzzy sets is proposed in this article. First, a definition of distance between two fuzzy sets is proposed. This definition is different from traditional ones for its dependent on the cardinal numbers and centroids of the two fuzzy sets. Then the method is used in designing a fuzzy controller. It is also pointed out that the fuzzy controller implemented through this way can approximate any continuous real function. The fuzzy controller proposed is able to handle the problem in the case that the input universe is not covered completely with the rule base.
2000, 22(6): 965-971.
Abstract:
The architecture and learning algorithm of traditional radial basis function (RBF) neural networks are surveyed in this paper. A generalized radial basis function model is proposed, which is more flexible and extensible. Based on the numerical solution to Mackey-Glass hematopoietic model equation, the prediction results obtained by radial basis function (RBF) model, gradient radial basis function (GRBF) model, and the generalized radial basis function model are compared and discussed, which show the effectiveness of the generalized model.
The architecture and learning algorithm of traditional radial basis function (RBF) neural networks are surveyed in this paper. A generalized radial basis function model is proposed, which is more flexible and extensible. Based on the numerical solution to Mackey-Glass hematopoietic model equation, the prediction results obtained by radial basis function (RBF) model, gradient radial basis function (GRBF) model, and the generalized radial basis function model are compared and discussed, which show the effectiveness of the generalized model.
2000, 22(6): 972-977.
Abstract:
In this paper, Hopf bifurcation of a neural network with time delay is discussed in detail. The stability of periodic solutions is also studied by utilizing center manifold theorem. Algorithms for determining the asymptotic stability, direction of bifurcation, period, and asymptotic form of these solutions are presented. All of the theoretical analyses are testified by computer simulations.
In this paper, Hopf bifurcation of a neural network with time delay is discussed in detail. The stability of periodic solutions is also studied by utilizing center manifold theorem. Algorithms for determining the asymptotic stability, direction of bifurcation, period, and asymptotic form of these solutions are presented. All of the theoretical analyses are testified by computer simulations.
2000, 22(6): 978-983.
Abstract:
This paper presents a novel asymptotical stability analysis of the equilibrium points in the unit hypercube for the Brain-State-in-a-Box neural model. Some sufficient conditions for the asymptotical stability of equilibrium points are derived using Ostrowskis theorem and the similarity transformation approach. Simulation examples are given to illustrate the effectiveness of new analysis method.
This paper presents a novel asymptotical stability analysis of the equilibrium points in the unit hypercube for the Brain-State-in-a-Box neural model. Some sufficient conditions for the asymptotical stability of equilibrium points are derived using Ostrowskis theorem and the similarity transformation approach. Simulation examples are given to illustrate the effectiveness of new analysis method.
2000, 22(6): 984-988.
Abstract:
Foliage penetrating VHF/UHF Ultra-WideBand (UWB) SAR can image hidden man-made targets such as military vehicles with wide-angle and ultra-wideband to achieve high resolutions in both range and azimuth, which has great military application value. Exploiting several multi-aperture SAR images, HMMs for man-made object and foliage clutter are developed separately in the paper, which can be utilized in detecting targets effectively to realize the pre-screening process in a ATR system.
Foliage penetrating VHF/UHF Ultra-WideBand (UWB) SAR can image hidden man-made targets such as military vehicles with wide-angle and ultra-wideband to achieve high resolutions in both range and azimuth, which has great military application value. Exploiting several multi-aperture SAR images, HMMs for man-made object and foliage clutter are developed separately in the paper, which can be utilized in detecting targets effectively to realize the pre-screening process in a ATR system.
2000, 22(6): 989-993.
Abstract:
Chaotic binary sequence based on double scroll attractor is produced by Wien bridge in this paper. Effects of the circuit parameters on the stochastic distribution properties and the correlation property of the proposed binary sequence are analyzed by means of the PSPICE simulation. The results show that properties of the binary sequence is better than that of the binary sequence based on logistic map and is similar to that of Bernoulli sequence so long as selecting parameters properly. It is suitable for the radar waveform.
Chaotic binary sequence based on double scroll attractor is produced by Wien bridge in this paper. Effects of the circuit parameters on the stochastic distribution properties and the correlation property of the proposed binary sequence are analyzed by means of the PSPICE simulation. The results show that properties of the binary sequence is better than that of the binary sequence based on logistic map and is similar to that of Bernoulli sequence so long as selecting parameters properly. It is suitable for the radar waveform.
2000, 22(6): 994-1000.
Abstract:
In this paper, the polarization degree of the target return in the optics region is investigated, on the basis of polarimetric and high-resolution radar system. The property is described by means of distribution parameter, the recognition of four kinds of aircraft targets is investigated and good results are obtained.
In this paper, the polarization degree of the target return in the optics region is investigated, on the basis of polarimetric and high-resolution radar system. The property is described by means of distribution parameter, the recognition of four kinds of aircraft targets is investigated and good results are obtained.
2000, 22(6): 1001-1006.
Abstract:
In theory, it is possible to synthesize any frequency response curve with the recursive MTI(Moving Target Indication) filters. As a result, the applied field of this kind of filter is wide. A new design method is presented to design flexibly a recursive MTI filter that can meet the specifications of the system. The method is based on the Genetic Algorithm(GA) and constitutes the fitness function with improvement factor, passband width and ripple of a filter. It speeds the search process and achieves near-global optimum parameters by means of the GA. Two kinds of classical recursive MTI filters are designed in this paper. The results demonstrate the validity of this design method that can design flexibly and quickly a required filter.
In theory, it is possible to synthesize any frequency response curve with the recursive MTI(Moving Target Indication) filters. As a result, the applied field of this kind of filter is wide. A new design method is presented to design flexibly a recursive MTI filter that can meet the specifications of the system. The method is based on the Genetic Algorithm(GA) and constitutes the fitness function with improvement factor, passband width and ripple of a filter. It speeds the search process and achieves near-global optimum parameters by means of the GA. Two kinds of classical recursive MTI filters are designed in this paper. The results demonstrate the validity of this design method that can design flexibly and quickly a required filter.
2000, 22(6): 1007-1015.
Abstract:
In this paper, a Fast Multipole Method (FMM) is developed to solving the scattered fields from three dimensional (3D) inhomogeneous dielectric scatterers. This generalized FMM is applied to the volume integral equation (3DV-FMM). The discrete formula of the volume integral equation was derived by the basic FMM and multi-level FMM. The FMM approach significantly reduces both the complexity of a matrix-vector multiplying and memory requirement. In calculation, the delta function is chosen as the basis and perfect convergence to the FMM results is achieved. As a typical example, the bistatic RCS of cubic scatterers with homogeneous, or inhomogeneous permittivity is calculated numerically. Distribution of electric currents on the cross-section of a dielectric cube is also obtained. Comparing with conventional moment method, the results of 3DV-FMM are exactly matched. However, the computer memory and CPU time are greatly reduced by using the 3DV-FMM. This method is applicable to the forward numerical simulation for 3D electromagnetic inverse problem.
In this paper, a Fast Multipole Method (FMM) is developed to solving the scattered fields from three dimensional (3D) inhomogeneous dielectric scatterers. This generalized FMM is applied to the volume integral equation (3DV-FMM). The discrete formula of the volume integral equation was derived by the basic FMM and multi-level FMM. The FMM approach significantly reduces both the complexity of a matrix-vector multiplying and memory requirement. In calculation, the delta function is chosen as the basis and perfect convergence to the FMM results is achieved. As a typical example, the bistatic RCS of cubic scatterers with homogeneous, or inhomogeneous permittivity is calculated numerically. Distribution of electric currents on the cross-section of a dielectric cube is also obtained. Comparing with conventional moment method, the results of 3DV-FMM are exactly matched. However, the computer memory and CPU time are greatly reduced by using the 3DV-FMM. This method is applicable to the forward numerical simulation for 3D electromagnetic inverse problem.
2000, 22(6): 1016-1021.
Abstract:
An efficient time signals prediction method combined with two-dimensional finite difference time domain (2D-FDTD) method has been proposed for the performance parameters computation of uniform microwave transmission lines. This hybrid method is especially suitable for the micron structures, and can account for the conductor loss efficiently. So it leads to a significant reduction in CPU time as compared with the conventional three-dimensional FDTD, which improves the efficiency. The simulation results are in good agreement with the results obtained by measurements.
An efficient time signals prediction method combined with two-dimensional finite difference time domain (2D-FDTD) method has been proposed for the performance parameters computation of uniform microwave transmission lines. This hybrid method is especially suitable for the micron structures, and can account for the conductor loss efficiently. So it leads to a significant reduction in CPU time as compared with the conventional three-dimensional FDTD, which improves the efficiency. The simulation results are in good agreement with the results obtained by measurements.
2000, 22(6): 1022-1027.
Abstract:
The TEM cell is limited in the upper useful test frequency but GHz TEM (GTEM) cell permits to overcome this restriction. This paper analyzes the transmisssion characteristics in GTEM cell using FDTD method in the nonorthogonal coordinate. The field distributions have been calculated and the upper useful frequency has been analyzed. The results are of great value to the using and designing of GTEM cells.
The TEM cell is limited in the upper useful test frequency but GHz TEM (GTEM) cell permits to overcome this restriction. This paper analyzes the transmisssion characteristics in GTEM cell using FDTD method in the nonorthogonal coordinate. The field distributions have been calculated and the upper useful frequency has been analyzed. The results are of great value to the using and designing of GTEM cells.
2000, 22(6): 1038-1040.
Abstract:
This paper analyses several key technologies of system control unit in the HDTV video decoder, and a hardware implementing method is given as well.
This paper analyses several key technologies of system control unit in the HDTV video decoder, and a hardware implementing method is given as well.
2000, 22(6): 1041-1045.
Abstract:
In this paper, the temporol-spatial coupling problem about antenna radiating and receiving of impulse signal SAR is analysed. Using back projection method, an impulse signal SAR imaging algorithm, antenna size how affects the impulse signal SAR azimuth accumulation is analysed in time-domain, the quantificational relation between azimuth accumulation and antenna size is presented. Finally, some usable conclusions about designing ultrawide band SAR antenna and selecting the parameter of transmitting are given.
In this paper, the temporol-spatial coupling problem about antenna radiating and receiving of impulse signal SAR is analysed. Using back projection method, an impulse signal SAR imaging algorithm, antenna size how affects the impulse signal SAR azimuth accumulation is analysed in time-domain, the quantificational relation between azimuth accumulation and antenna size is presented. Finally, some usable conclusions about designing ultrawide band SAR antenna and selecting the parameter of transmitting are given.
2000, 22(6): 1028-1037.
Abstract:
Markov random field methodology is a new noticeable research field in computer vision. In this paper, a general analysis framework and relative references of MRF modelbased methodology are presented, the approaches for image segmentation and restoration are reviewed, and a few possible trends are discussed as well.
Markov random field methodology is a new noticeable research field in computer vision. In this paper, a general analysis framework and relative references of MRF modelbased methodology are presented, the approaches for image segmentation and restoration are reviewed, and a few possible trends are discussed as well.
