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2001 Vol. 23, No. 4
Display Method:
2001, 23(4): 313-320.
Abstract:
The scattering function is one of most important mathematical method describing time-frequency dispersion channel performance, which embodies a concentrated reflection of the dispersion characteristics of the mobile radio channel in time and frequency domain, and reflects the angle dispersion distributed performance of the channel to a certain extent. The paper researches the scatter function as well as its mathematical models of multipath dispersion channel in urban microcellular mobile Communications, the...
The scattering function is one of most important mathematical method describing time-frequency dispersion channel performance, which embodies a concentrated reflection of the dispersion characteristics of the mobile radio channel in time and frequency domain, and reflects the angle dispersion distributed performance of the channel to a certain extent. The paper researches the scatter function as well as its mathematical models of multipath dispersion channel in urban microcellular mobile Communications, the...
2001, 23(4): 321-326.
Abstract:
A kind of ID-based interactive user authentication and two-way authentication schemes are presented in this paper and extended to form a new ID-based interactive shared authentication scheme, which enables more than t out of n verifiers in authentication system to validate a user s identity, such that the cheating trick of few administrators in the authentication system can be prevented, thus the security class and the availiability of the authentication system are improved.
A kind of ID-based interactive user authentication and two-way authentication schemes are presented in this paper and extended to form a new ID-based interactive shared authentication scheme, which enables more than t out of n verifiers in authentication system to validate a user s identity, such that the cheating trick of few administrators in the authentication system can be prevented, thus the security class and the availiability of the authentication system are improved.
2001, 23(4): 327-331.
Abstract:
This paper applies segmental unit into HMM for speech recognition. In this model, several successive frames are combined and treated as an input vector. It expects that segmental unit input HMM would be effective to describe the inter-frame correlation information and has also proposed the MGDF and RBF to further improve output probability function. By comparing them with the traditional HMMs based on their speech recognition performance rates through the experiments of speaker-independent spoken digit (isolated/connected) recognition,the validity of the proposed appraoch could be verified.
This paper applies segmental unit into HMM for speech recognition. In this model, several successive frames are combined and treated as an input vector. It expects that segmental unit input HMM would be effective to describe the inter-frame correlation information and has also proposed the MGDF and RBF to further improve output probability function. By comparing them with the traditional HMMs based on their speech recognition performance rates through the experiments of speaker-independent spoken digit (isolated/connected) recognition,the validity of the proposed appraoch could be verified.
2001, 23(4): 332-337.
Abstract:
This paper presents a compound neural network model, i.e., adaptive fuzzy neural network (AFNN), which can be used for identifying the complicated nonlinear system. AFNN has a simple structure and possesses the ability of universal approximation. It is capable of overcoming the error of system identification due to the existence of some changing points and improving the accuracy of identification of the whole system. The effectiveness of the model is tested on the identification result of missile attacking area.
This paper presents a compound neural network model, i.e., adaptive fuzzy neural network (AFNN), which can be used for identifying the complicated nonlinear system. AFNN has a simple structure and possesses the ability of universal approximation. It is capable of overcoming the error of system identification due to the existence of some changing points and improving the accuracy of identification of the whole system. The effectiveness of the model is tested on the identification result of missile attacking area.
2001, 23(4): 338-344.
Abstract:
In the beamformer based on sample covariance matrix inverse (SMI) algorithm, the calculation of weight vector comprises the components of interferences and noise. The projection method comprises the components of interferences. It induces the imperfective results of the beamformer. Under the environments of high signal-to-noise ratio (SNR) and large steering error, SMI algorithm and the projection method are invalid. The cyclic beamformer of utilizing signal s cyclostationarity is proposed to resolve the problem above-mentioned. The simulation results verify the cyclic beamforming algorithm.
In the beamformer based on sample covariance matrix inverse (SMI) algorithm, the calculation of weight vector comprises the components of interferences and noise. The projection method comprises the components of interferences. It induces the imperfective results of the beamformer. Under the environments of high signal-to-noise ratio (SNR) and large steering error, SMI algorithm and the projection method are invalid. The cyclic beamformer of utilizing signal s cyclostationarity is proposed to resolve the problem above-mentioned. The simulation results verify the cyclic beamforming algorithm.
2001, 23(4): 345-353.
Abstract:
A class of learning algorithms is drived for blind separation of independent source signals in this paper. These algorithms are based on minimizing a contrast function defined in terms of the Kullback-Leibler distance. By utilizing the technique of multivariate density esti-mation, two types of separating algorithms are obtained. Simulations illustrate the effectiveness of the algorithms.
A class of learning algorithms is drived for blind separation of independent source signals in this paper. These algorithms are based on minimizing a contrast function defined in terms of the Kullback-Leibler distance. By utilizing the technique of multivariate density esti-mation, two types of separating algorithms are obtained. Simulations illustrate the effectiveness of the algorithms.
2001, 23(4): 354-359.
Abstract:
This paper discusses shortcomings of adjacent-frame difference. Based on the image energy and high order statistic (HOS) theory, background reconstruction constraint con-ditions are setup. Under the help of block- processing technology, background is reconstructed quickly. The DSP based platform tests indicate that the background can be recovered lossless in about one second, while moving regions estimations are not influenced by target speed.
This paper discusses shortcomings of adjacent-frame difference. Based on the image energy and high order statistic (HOS) theory, background reconstruction constraint con-ditions are setup. Under the help of block- processing technology, background is reconstructed quickly. The DSP based platform tests indicate that the background can be recovered lossless in about one second, while moving regions estimations are not influenced by target speed.
2001, 23(4): 360-364.
Abstract:
In this paper the grating lobe induced by the coupling of range and direction in the synthetic impulse for SIAR is studied and the reason why the grating lobe is generated is analyzed .Two methods that can eliminate the grating lobe are presented. Computer simulation results show these methods are effective.
In this paper the grating lobe induced by the coupling of range and direction in the synthetic impulse for SIAR is studied and the reason why the grating lobe is generated is analyzed .Two methods that can eliminate the grating lobe are presented. Computer simulation results show these methods are effective.
2001, 23(4): 365-372.
Abstract:
Cross-range scaling of low-resolution radar is very important to obtain correctly cross-range image and target classification and recognition. According to the technology of in-verse synthetic aperture radar(ISAR), the cross-range scale depends on both radar wavelength and rotating angle of target relative to radar-line-of-sight(RLOS) during the coherent accumu-lation. The former is known while the latter is difficult to determine especially in the case of ISAR. In this paper, a new approach is proposed which is based on the principle of synthetic array and interferometric inverse synthetic aperture. The phase difference of some scatters between two instant cross-range images by two antennae which are placed on one level, can be calculated. The proposed algorithm is applied to the emulational data of two antennae. The theoretical analysis and the processing results show that the proposed method is correct and effective.
Cross-range scaling of low-resolution radar is very important to obtain correctly cross-range image and target classification and recognition. According to the technology of in-verse synthetic aperture radar(ISAR), the cross-range scale depends on both radar wavelength and rotating angle of target relative to radar-line-of-sight(RLOS) during the coherent accumu-lation. The former is known while the latter is difficult to determine especially in the case of ISAR. In this paper, a new approach is proposed which is based on the principle of synthetic array and interferometric inverse synthetic aperture. The phase difference of some scatters between two instant cross-range images by two antennae which are placed on one level, can be calculated. The proposed algorithm is applied to the emulational data of two antennae. The theoretical analysis and the processing results show that the proposed method is correct and effective.
2001, 23(4): 373-378.
Abstract:
With the analysis of R-D algorithm, the relationship between the frequency of radar, the signal frequency width and the squint angle is deduced. The result is identified by computer simulation.
With the analysis of R-D algorithm, the relationship between the frequency of radar, the signal frequency width and the squint angle is deduced. The result is identified by computer simulation.
2001, 23(4): 379-387.
Abstract:
An autofocus algorithm based on RELAX is presented. Assuming there exist multiple dominant scatterers in each range bin (other smaller scatterers are treated as clutter), the algorithm performs the phase error correction and the parameter estimation of the dominant scatterers alternatively by adopting an iterative procedure. The algorithm does not require that the clutter and noise in each range bin to be of certain distribution model, and it can be used to estimate all kinds of phase errors. Thus the algorithm is very robust. The results obtained in autofocusing experiments on real SAR/ISAR data show that the algorithm is very efficacious.
An autofocus algorithm based on RELAX is presented. Assuming there exist multiple dominant scatterers in each range bin (other smaller scatterers are treated as clutter), the algorithm performs the phase error correction and the parameter estimation of the dominant scatterers alternatively by adopting an iterative procedure. The algorithm does not require that the clutter and noise in each range bin to be of certain distribution model, and it can be used to estimate all kinds of phase errors. Thus the algorithm is very robust. The results obtained in autofocusing experiments on real SAR/ISAR data show that the algorithm is very efficacious.
2001, 23(4): 388-395.
Abstract:
The extended Huygens-Fresnel principle is utilized to make analysis of scattering characteristics of diffuse targets in the turbulent atmosphere with considering the fluctuation of the log-amplitude, the covariance function and variance of the scattering intensity are derived in detail, and the numerical results are given. The influence of turbulence strength, wavelength and propagating distance on the covariance function and normalized variance of the scattering intensity is discussed.
The extended Huygens-Fresnel principle is utilized to make analysis of scattering characteristics of diffuse targets in the turbulent atmosphere with considering the fluctuation of the log-amplitude, the covariance function and variance of the scattering intensity are derived in detail, and the numerical results are given. The influence of turbulence strength, wavelength and propagating distance on the covariance function and normalized variance of the scattering intensity is discussed.
2001, 23(4): 396-402.
Abstract:
On the basis of theory of ternary essential circuits elements, this paper presents a theory of ternary dynamic and static generalized sequential machine, which is applicable to static circuits as well as dynamic circuits. As regards static circuits, several ternary flip-flops perfect characteristic equations are proved to describe its action at all times, instead of its traditional characteristic equations, in order to unify the theory of temary sychronous and asychronous sequential circuits. As regards dynamic circuits, this paper uses capacitors, instead of ternary flip-flops, to memorize ternary informations for the realization of ternary dynamic circuits, especially ternary sychronous dynamic sequential circuit without flip-flops, because the difference between dynamic circuit and static circuit is mainly its load property. The theory of ternary essential circuit elements is a very useful means for unifying sequential circuit theory between static circuits and dynamic circuits, and between ternary sychronous and asychronous sequential circuits.
On the basis of theory of ternary essential circuits elements, this paper presents a theory of ternary dynamic and static generalized sequential machine, which is applicable to static circuits as well as dynamic circuits. As regards static circuits, several ternary flip-flops perfect characteristic equations are proved to describe its action at all times, instead of its traditional characteristic equations, in order to unify the theory of temary sychronous and asychronous sequential circuits. As regards dynamic circuits, this paper uses capacitors, instead of ternary flip-flops, to memorize ternary informations for the realization of ternary dynamic circuits, especially ternary sychronous dynamic sequential circuit without flip-flops, because the difference between dynamic circuit and static circuit is mainly its load property. The theory of ternary essential circuit elements is a very useful means for unifying sequential circuit theory between static circuits and dynamic circuits, and between ternary sychronous and asychronous sequential circuits.
2001, 23(4): 403-407.
Abstract:
Netvrork traffic prediction is important for netvrork control and bandwidth alloca-tion. This paper first introduces how to get optimal forecasting values, and provides prediction procedure for FARIMA models. And then provides a prediction method for self-similar traffic with compensation function and also gives out an example to demonstrate how to use this method in network control.
Netvrork traffic prediction is important for netvrork control and bandwidth alloca-tion. This paper first introduces how to get optimal forecasting values, and provides prediction procedure for FARIMA models. And then provides a prediction method for self-similar traffic with compensation function and also gives out an example to demonstrate how to use this method in network control.
2001, 23(4): 408-412.
Abstract:
This paper puts foward a novel way to achieve chaotic synchronization. Take the modified Chua s circuit as example, the numerical simulation shows this way is very successful. The message signal can be as large as the chaotic carrier signal, so the signal-to-noise ratio can be very high even when only one signal is transmitted. The synchronization is excellent and the retrieved signal is virtually perfect.
This paper puts foward a novel way to achieve chaotic synchronization. Take the modified Chua s circuit as example, the numerical simulation shows this way is very successful. The message signal can be as large as the chaotic carrier signal, so the signal-to-noise ratio can be very high even when only one signal is transmitted. The synchronization is excellent and the retrieved signal is virtually perfect.
2001, 23(4): 413-416.
Abstract:
Turbo code is a new class of error correcting and achieves almost reliable commu-nication when SNR is very close to the Shannon-Limit. Turbo encoder consists of a parallel concatenation of two or more convolutional codes and interleaver. A new parameter effective free distance d2 was proposed by S. Benedetto and G. Montorsi(1996) and two upper bounds on d2 were stated without proof by D. Divsalar and R. J. McEliece (1996). This paper proofs the two upper bounds on d2.
Turbo code is a new class of error correcting and achieves almost reliable commu-nication when SNR is very close to the Shannon-Limit. Turbo encoder consists of a parallel concatenation of two or more convolutional codes and interleaver. A new parameter effective free distance d2 was proposed by S. Benedetto and G. Montorsi(1996) and two upper bounds on d2 were stated without proof by D. Divsalar and R. J. McEliece (1996). This paper proofs the two upper bounds on d2.
