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2005 Vol. 27, No. 1
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2005, 27(1): 1-5.
Abstract:
The high squint SAR signal features large range walk and small range curvature, which enable the raw data be compressed in range and azimuth separately. But in case of large azimuth scene size , complex algorithms must be used to cope with the constraint of the focus depth. In this paper a new two-dimension-separated method is presented to compensate the azimuth-dependent chirp rate using a non-linear chirp scaling operation. Finally simulation results are presented to verify the method.
The high squint SAR signal features large range walk and small range curvature, which enable the raw data be compressed in range and azimuth separately. But in case of large azimuth scene size , complex algorithms must be used to cope with the constraint of the focus depth. In this paper a new two-dimension-separated method is presented to compensate the azimuth-dependent chirp rate using a non-linear chirp scaling operation. Finally simulation results are presented to verify the method.
2005, 27(1): 6-9.
Abstract:
SAR image matching is important to SAR applications. This paper presents a method to fast match SAR images based on image feature. Edge detection and image segmentation are carried out firstly. Then image matching is performed based on the feature of segmented image. The test carried out with real SAR images has achieved good results.
SAR image matching is important to SAR applications. This paper presents a method to fast match SAR images based on image feature. Edge detection and image segmentation are carried out firstly. Then image matching is performed based on the feature of segmented image. The test carried out with real SAR images has achieved good results.
2005, 27(1): 10-12.
Abstract:
In a general radar and communication system, the digital quadrature detection is necessary for implementing direct IF or RF sampling. The Digital Product Detection (DPD), applied easily in a real engineering, is a method to implement the digital quadrature detection. But the datum acquired by the method should be corrected. The paper presents the polyphase filtering to correct the I/Q datum acquired in combination with the Synthetic Aperture Radar (SAR) signal processing by contrast with Bessel filtering. The simulation results show that the method is simpler, more flexible and applied easily. The correct error by the polyphase filter with the same order is smaller than the error by the same order Bessel filter. The former maximum absolute error is 5.839410-4. The latter maximum absolute error is 9.30710-4. In addition, the polyphase filtering can implement the unequal interval filtering easily.
In a general radar and communication system, the digital quadrature detection is necessary for implementing direct IF or RF sampling. The Digital Product Detection (DPD), applied easily in a real engineering, is a method to implement the digital quadrature detection. But the datum acquired by the method should be corrected. The paper presents the polyphase filtering to correct the I/Q datum acquired in combination with the Synthetic Aperture Radar (SAR) signal processing by contrast with Bessel filtering. The simulation results show that the method is simpler, more flexible and applied easily. The correct error by the polyphase filter with the same order is smaller than the error by the same order Bessel filter. The former maximum absolute error is 5.839410-4. The latter maximum absolute error is 9.30710-4. In addition, the polyphase filtering can implement the unequal interval filtering easily.
2005, 27(1): 13-16.
Abstract:
A new IMM algorithm for tracking maneuvering target is proposed, which only uses two models that consist of a CS model and an augmented CV model for interaction. The CS model which uses the state variable with normal acceleration and tangent acceleration is fit for the accurate tracking of coordinated turn movement. This method is not subjected to the limit of the magnitude and change of turn rate, and has more flexibility to uncertain parameters. The simulation shows that this algorithm is superior to the conventional IMM-CV/CT algorithm which uses more than three models for interaction in terms of the accuracy of tracking and adaptation. Because this algorithm can estimate the normal and tangent acceleration, it may be used to implement the tracking for the complexly and highly maneuvering target after appropriate model-set design.
A new IMM algorithm for tracking maneuvering target is proposed, which only uses two models that consist of a CS model and an augmented CV model for interaction. The CS model which uses the state variable with normal acceleration and tangent acceleration is fit for the accurate tracking of coordinated turn movement. This method is not subjected to the limit of the magnitude and change of turn rate, and has more flexibility to uncertain parameters. The simulation shows that this algorithm is superior to the conventional IMM-CV/CT algorithm which uses more than three models for interaction in terms of the accuracy of tracking and adaptation. Because this algorithm can estimate the normal and tangent acceleration, it may be used to implement the tracking for the complexly and highly maneuvering target after appropriate model-set design.
2005, 27(1): 17-20.
Abstract:
Fast and precise location method plays an important role in the data association and the target tracking for the passive sensor system. In order to solve the typical problem of the target location encountered in the netted passive sensor system, the vertical location method is proposed. Simulation results show that the vertical location method is an effective target location method, and its positioning error variance can achieve the Camer-Rao lower bound.
Fast and precise location method plays an important role in the data association and the target tracking for the passive sensor system. In order to solve the typical problem of the target location encountered in the netted passive sensor system, the vertical location method is proposed. Simulation results show that the vertical location method is an effective target location method, and its positioning error variance can achieve the Camer-Rao lower bound.
2005, 27(1): 21-25.
Abstract:
In this paper, a new time-frequency representation method, adaptive signal expansion algorithm! is presented. The algorithm is based on that essential character of signal space, initial value estimation and precise resolution are obtained simultaneously. Signal is adaptively expanded to a sum of chirplet elementary functions by using match pursuit algorithm. Then, according to expansion coefficients and elementary function parameters, adaptive time frequency distribution is obtained. Its time frequency congregate, noise-reduction and time frequency resolution are not only better than the general time frequency distribution but also better than adaptive time frequency distribution reported and it is able to characterize the signals nature exactly. The validity of the algorithm and the performance of adaptive time frequency distribution are tested by numerical simulations.
In this paper, a new time-frequency representation method, adaptive signal expansion algorithm! is presented. The algorithm is based on that essential character of signal space, initial value estimation and precise resolution are obtained simultaneously. Signal is adaptively expanded to a sum of chirplet elementary functions by using match pursuit algorithm. Then, according to expansion coefficients and elementary function parameters, adaptive time frequency distribution is obtained. Its time frequency congregate, noise-reduction and time frequency resolution are not only better than the general time frequency distribution but also better than adaptive time frequency distribution reported and it is able to characterize the signals nature exactly. The validity of the algorithm and the performance of adaptive time frequency distribution are tested by numerical simulations.
2005, 27(1): 26-30.
Abstract:
Based on a novel windowed overlapping adaptive filter, LMS algorithm with overlapping idea is introduced. In terms of the smoothness of signals processed by overlapping, a new Windowed Overlapping LMS algorithm(WO-LMS)is presented that combines the windowed overlapping idea and LMS algorithm. In comparison with traditional LMS algorithm, WO-LMS algorithm can achieve both lower steady mean square error and faster convergence speed. Convergence property is theoretically analyzed, and the experimental results prove the superiority of WO-LMS compared with LMS algorithm.
Based on a novel windowed overlapping adaptive filter, LMS algorithm with overlapping idea is introduced. In terms of the smoothness of signals processed by overlapping, a new Windowed Overlapping LMS algorithm(WO-LMS)is presented that combines the windowed overlapping idea and LMS algorithm. In comparison with traditional LMS algorithm, WO-LMS algorithm can achieve both lower steady mean square error and faster convergence speed. Convergence property is theoretically analyzed, and the experimental results prove the superiority of WO-LMS compared with LMS algorithm.
2005, 27(1): 31-34.
Abstract:
Information authentication technique is an important inspects of network security, and its motive lies in authentication of the integrity and creditability of information. Based on the analysis of the previous image authentication techniques, a new effective image authentication technique is proposed based on the interested region. Firstly, the original image is divided into a certain size preliminary image blocks. Then on the basis of the interested region given by users, the preliminary image block is divided into smaller blocks, at the same time the signature of each image block is extracted. Finally the signature of image blocks is embedded into intermediate frequency coefficient of image blocks. Experimental results are provided to demonstrate the effectiveness, self-adaptability, and validity of the method.
Information authentication technique is an important inspects of network security, and its motive lies in authentication of the integrity and creditability of information. Based on the analysis of the previous image authentication techniques, a new effective image authentication technique is proposed based on the interested region. Firstly, the original image is divided into a certain size preliminary image blocks. Then on the basis of the interested region given by users, the preliminary image block is divided into smaller blocks, at the same time the signature of each image block is extracted. Finally the signature of image blocks is embedded into intermediate frequency coefficient of image blocks. Experimental results are provided to demonstrate the effectiveness, self-adaptability, and validity of the method.
Incremental Wiener Filter and Space-Adaptive Regularization Based Super-Resolution Image Restoration
2005, 27(1): 35-38.
Abstract:
A new method of super-resolution image restoration is proposed in the paper. In this method, the piecewise smoothness of space-adaptive regularization combines with the rapid convergence of incremental Wiener filter and through an iteration process with a priori constraint about image, one super-resolution image is estimated from several low-resolution images. Simulations show that the method can implement restoration effectively and has good convergence.
A new method of super-resolution image restoration is proposed in the paper. In this method, the piecewise smoothness of space-adaptive regularization combines with the rapid convergence of incremental Wiener filter and through an iteration process with a priori constraint about image, one super-resolution image is estimated from several low-resolution images. Simulations show that the method can implement restoration effectively and has good convergence.
2005, 27(1): 39-42.
Abstract:
A method of moving object detection based on two dimensional (2D) spatio-temporal entropic thresholding is proposed in this paper. The characteristics of several common approaches for moving object detection are analyzed, and 2D entropic thresholding method is used to detect the structural region of the moving object. The 2D thresholding method is first deduced. A fast algorithm for entropic thresholding is put forward. The experimental results show that this method can be used to detect the moving object, and reduce the computational time efficiently.
A method of moving object detection based on two dimensional (2D) spatio-temporal entropic thresholding is proposed in this paper. The characteristics of several common approaches for moving object detection are analyzed, and 2D entropic thresholding method is used to detect the structural region of the moving object. The 2D thresholding method is first deduced. A fast algorithm for entropic thresholding is put forward. The experimental results show that this method can be used to detect the moving object, and reduce the computational time efficiently.
2005, 27(1): 43-46.
Abstract:
An approach to detecting moving objects from infrared image sequence on displacing background is proposed in this paper. First the correlation matching technique is used for registering five pictures with the sixth one. Then the registered images are processed to calculate the image differences between the first and fourth, the second and fifth, the third and sixth. After these difference images are multiplied, a very high correlation peak is obtained. Using this method a central point for tracking window can be provided. The experimental results illustrate that this approach is available to this situation.
An approach to detecting moving objects from infrared image sequence on displacing background is proposed in this paper. First the correlation matching technique is used for registering five pictures with the sixth one. Then the registered images are processed to calculate the image differences between the first and fourth, the second and fifth, the third and sixth. After these difference images are multiplied, a very high correlation peak is obtained. Using this method a central point for tracking window can be provided. The experimental results illustrate that this approach is available to this situation.
2005, 27(1): 47-50.
Abstract:
This paper presents a research on the algorithm of optimal set of statistically uncorrelated discriminant vectors. An improved algorithm has been proposed on the basis of the analysis of the conventional algorithm of statistical uncorrelated discriminant vectors, which solves the optimal set of statistically uncorrelated discriminant vectors in the eigen space of the within-class scatter matrix Sw. The dimension of images has been reduced using the dimension reduction method based on image discriminant analysis in order to speed the process of feature extraction. The numerical experiments on facial databases of ORL and Yale show the effectiveness of the proposed method.
This paper presents a research on the algorithm of optimal set of statistically uncorrelated discriminant vectors. An improved algorithm has been proposed on the basis of the analysis of the conventional algorithm of statistical uncorrelated discriminant vectors, which solves the optimal set of statistically uncorrelated discriminant vectors in the eigen space of the within-class scatter matrix Sw. The dimension of images has been reduced using the dimension reduction method based on image discriminant analysis in order to speed the process of feature extraction. The numerical experiments on facial databases of ORL and Yale show the effectiveness of the proposed method.
2005, 27(1): 51-55.
Abstract:
This paper proposes a method that can automatically obtain common lineshape in the spectrum data set based on Complex Principal Component Analysis(CPCA). which can correct frequency shifts and damping factor shifts effectively. This method aligns frequency at first, then extends CPCA to the correction of damping factor shifts in a single resonant peak across spectra. Through this method, frequency and damping factor alignment are successfully achieved. In terms of computation time and estimation precision this method is significantly better than that of PCA.
This paper proposes a method that can automatically obtain common lineshape in the spectrum data set based on Complex Principal Component Analysis(CPCA). which can correct frequency shifts and damping factor shifts effectively. This method aligns frequency at first, then extends CPCA to the correction of damping factor shifts in a single resonant peak across spectra. Through this method, frequency and damping factor alignment are successfully achieved. In terms of computation time and estimation precision this method is significantly better than that of PCA.
2005, 27(1): 56-59.
Abstract:
A novel image fusion algorithm using wavelet transform multiscale edges detection is proposed in this paper. This wavelet analysis image fusion method is feature-based. The source images are fused using their multiscale edges information. In order to preserve fusion image edges better, the denoising and edges detection combined are statistical parameters is used to evaluate multifocus image fusion performance. The technique determining optimal decomposition level has explicit physical meaning in this paper. Comparing source images entropy with fusion image entropy at the same decomposition level, if arbitrary source image entropy is larger than the fusion image entropy, it is not neccesary to make next level decomposition. Experimental results demonstrate the effectiveness of the algorithm which increases entropy and standard deviation of fusion image.
A novel image fusion algorithm using wavelet transform multiscale edges detection is proposed in this paper. This wavelet analysis image fusion method is feature-based. The source images are fused using their multiscale edges information. In order to preserve fusion image edges better, the denoising and edges detection combined are statistical parameters is used to evaluate multifocus image fusion performance. The technique determining optimal decomposition level has explicit physical meaning in this paper. Comparing source images entropy with fusion image entropy at the same decomposition level, if arbitrary source image entropy is larger than the fusion image entropy, it is not neccesary to make next level decomposition. Experimental results demonstrate the effectiveness of the algorithm which increases entropy and standard deviation of fusion image.
2005, 27(1): 60-63.
Abstract:
The embedded systems are gradually becoming the first choice of platforms which should be used for real-time speech recognition system. This paper discusses the computation complexity factors of HMM-based continuous speech recognition for embedded system. An optimized way integrating feature masking and pruning is presented to reduce the computation complexity and keep the recognition accuracy. The experiments for embedded system show that, comparing with the base-line system, the computation time is reduced from 100% to 27.91%, and the recognition accuracy is degraded only from 89.65% to 89.41%.
The embedded systems are gradually becoming the first choice of platforms which should be used for real-time speech recognition system. This paper discusses the computation complexity factors of HMM-based continuous speech recognition for embedded system. An optimized way integrating feature masking and pruning is presented to reduce the computation complexity and keep the recognition accuracy. The experiments for embedded system show that, comparing with the base-line system, the computation time is reduced from 100% to 27.91%, and the recognition accuracy is degraded only from 89.65% to 89.41%.
2005, 27(1): 64-68.
Abstract:
This paper presents a robust visual feature based on Visemic LDA for audio visual speech recognition, which captures dynamic lip contour information and reflects the viseme classes of visual speech. The paper also introduces an automatic labeling method using the speech recognition results for LDA training data, which avoids the tedious manually labeling work and labeling errors. Experimental results show that the audio visual speech recognition system based on the visual features presented in this paper can greatly increase the speech recognition rate in noisy conditions. The combination of the visual feature with multi-stream HMM can bring the recognition rate of over 80% at a 10dB SNR noisy condition.
This paper presents a robust visual feature based on Visemic LDA for audio visual speech recognition, which captures dynamic lip contour information and reflects the viseme classes of visual speech. The paper also introduces an automatic labeling method using the speech recognition results for LDA training data, which avoids the tedious manually labeling work and labeling errors. Experimental results show that the audio visual speech recognition system based on the visual features presented in this paper can greatly increase the speech recognition rate in noisy conditions. The combination of the visual feature with multi-stream HMM can bring the recognition rate of over 80% at a 10dB SNR noisy condition.
2005, 27(1): 69-71.
Abstract:
A new distance metric for MLC/PDL (MultiLevel Coding/ Parallel Decoding of Levels) with MQAM constellation is proved to be applicable when punctured convolutional code is used as component code over Rayleigh fading channel. The efficiency has been demonstrated by detailed simulation results. The performance comparison between punctured convolutional code and block code under the same condition is also given.
A new distance metric for MLC/PDL (MultiLevel Coding/ Parallel Decoding of Levels) with MQAM constellation is proved to be applicable when punctured convolutional code is used as component code over Rayleigh fading channel. The efficiency has been demonstrated by detailed simulation results. The performance comparison between punctured convolutional code and block code under the same condition is also given.
2005, 27(1): 72-74.
Abstract:
The semi-blind Constant Modulus (CM) algorithm which applied in the Multi-User Detection (MUD) of CDMA is studied. This approach fully utilizes all known users information, performs not-blind detector to suppress the interferes within the cell, and exploits blind detector to suppress the inter-cell interference. Compared with the blind CM algorithm and the decorrelating algorithm, the proposed semi-blind CM algorithm exhibits better SIR and BER performances and it is more robust when the system is heavily loaded.
The semi-blind Constant Modulus (CM) algorithm which applied in the Multi-User Detection (MUD) of CDMA is studied. This approach fully utilizes all known users information, performs not-blind detector to suppress the interferes within the cell, and exploits blind detector to suppress the inter-cell interference. Compared with the blind CM algorithm and the decorrelating algorithm, the proposed semi-blind CM algorithm exhibits better SIR and BER performances and it is more robust when the system is heavily loaded.
2005, 27(1): 75-77.
Abstract:
Power control and multiuser detection are two ways to cope with Multiple Access Interference (MAI) and near-far effect. This paper proposed a new scheme for DS-CDMA system combined power control and multiuser detection. This scheme can effectively mitigate interference of other users, and minimize the total transmit power under the constraint that all the users achieve the requisition of Signal-to-Interference Ratio(SIR), also the convergence of the SIRs to the common target SIR rapidly.
Power control and multiuser detection are two ways to cope with Multiple Access Interference (MAI) and near-far effect. This paper proposed a new scheme for DS-CDMA system combined power control and multiuser detection. This scheme can effectively mitigate interference of other users, and minimize the total transmit power under the constraint that all the users achieve the requisition of Signal-to-Interference Ratio(SIR), also the convergence of the SIRs to the common target SIR rapidly.
2005, 27(1): 78-81.
Abstract:
In the paper, a varied step length LMS algorithm is adopted in space-time multiuser receiver, in which a new bierror function is used to solve the constrained optimization problem. Furthermore, based on the character of the users signals in fading channels, a new standard is presented to filter the users signals in advance. The method will reduce the running cost of the system greatly and present a new controllable tread of f means between the system performance and its running cost. The above algorithm is verified by the following simulations.
In the paper, a varied step length LMS algorithm is adopted in space-time multiuser receiver, in which a new bierror function is used to solve the constrained optimization problem. Furthermore, based on the character of the users signals in fading channels, a new standard is presented to filter the users signals in advance. The method will reduce the running cost of the system greatly and present a new controllable tread of f means between the system performance and its running cost. The above algorithm is verified by the following simulations.
2005, 27(1): 82-85.
Abstract:
A novel CDMA BLAST space-time code technique is proposed in this paper for the down link in a cellular CDMA system. Scrambling codes and orthogonal spreading codes are employed to identify different transmit antennas and different users, respectively. Due to good auto- and cross-correlation proprieties of the scrambling codes, the proposed scheme can obtain considerable improvement in the bit error rate performance without sacrifice of the precious orthogonal code resources.
A novel CDMA BLAST space-time code technique is proposed in this paper for the down link in a cellular CDMA system. Scrambling codes and orthogonal spreading codes are employed to identify different transmit antennas and different users, respectively. Due to good auto- and cross-correlation proprieties of the scrambling codes, the proposed scheme can obtain considerable improvement in the bit error rate performance without sacrifice of the precious orthogonal code resources.
2005, 27(1): 86-89.
Abstract:
This paper presents a novel power-limited pre-compensation method in MC-CDMA/TDD systems, which can avoid pilot insertion on the uplink and increase the spectral/power efficiency. To keep the transmission power constant, only the phase of signal is predistorted before transmission at the mobile stations transmitter while the amplitude estimation and compensation of received signal are performed at the base stations receiver on the uplink. The performance degradation due to the time varying channel is also included in the analysis. Simulation results show the good performance of the proposed pre-compensation method.
This paper presents a novel power-limited pre-compensation method in MC-CDMA/TDD systems, which can avoid pilot insertion on the uplink and increase the spectral/power efficiency. To keep the transmission power constant, only the phase of signal is predistorted before transmission at the mobile stations transmitter while the amplitude estimation and compensation of received signal are performed at the base stations receiver on the uplink. The performance degradation due to the time varying channel is also included in the analysis. Simulation results show the good performance of the proposed pre-compensation method.
2005, 27(1): 90-94.
Abstract:
A Single Carrier/Frequency Domain Equalization (SC/FDE) system with time multiplexed pilot channel is designed. In this system, the Doppler-shift of the time-varying multi-path channel is estimated by calculating the Level Crossing Rate (LCR) of the signal envelope with the channel coefficient estimation on the effective fingers. Based on the Doppler-shift estimation and its relationship with pilot sampling rate, the slot structure and the pilot density are adjusted adaptively, which ensure high system capacity and good receiving performance in a wide range of mobile velocities.
A Single Carrier/Frequency Domain Equalization (SC/FDE) system with time multiplexed pilot channel is designed. In this system, the Doppler-shift of the time-varying multi-path channel is estimated by calculating the Level Crossing Rate (LCR) of the signal envelope with the channel coefficient estimation on the effective fingers. Based on the Doppler-shift estimation and its relationship with pilot sampling rate, the slot structure and the pilot density are adjusted adaptively, which ensure high system capacity and good receiving performance in a wide range of mobile velocities.
2005, 27(1): 95-98.
Abstract:
In this paper, the Doppler-shift of the time-varying multi-path channel is estimated by calculating the Level Crossing Rate (LCR) of the signal envelope of the channel coefficient estimates on the effective fingers. The effect of noise is analyzed , and an improved accurate estimation method is proposed to get the high estimation accuracy in all kinds of velocity and signal-to-noise ratio.
In this paper, the Doppler-shift of the time-varying multi-path channel is estimated by calculating the Level Crossing Rate (LCR) of the signal envelope of the channel coefficient estimates on the effective fingers. The effect of noise is analyzed , and an improved accurate estimation method is proposed to get the high estimation accuracy in all kinds of velocity and signal-to-noise ratio.
2005, 27(1): 99-103.
Abstract:
Since the channel has slowly-varying delays and directions of arrival and fast-varying faded amplitudes, benefits can be obtained by space-time processing base these channel features. In this paper, the space-time subspace and amplitude tracking algorithms using adaptive filtering technique are proposed by taking a training-sequence-based OFDM system with transmitter diversity as a multi-slot communications system and the channel estimation performance is observably improved. At the same time, this paper gives some simulations and comparisons of the performance of the different tracking algorithms.
Since the channel has slowly-varying delays and directions of arrival and fast-varying faded amplitudes, benefits can be obtained by space-time processing base these channel features. In this paper, the space-time subspace and amplitude tracking algorithms using adaptive filtering technique are proposed by taking a training-sequence-based OFDM system with transmitter diversity as a multi-slot communications system and the channel estimation performance is observably improved. At the same time, this paper gives some simulations and comparisons of the performance of the different tracking algorithms.
2005, 27(1): 104-107.
Abstract:
This paper proposes an adaptive rood pattern search, a new fast block-matching motion estimation algorithm. It combines the advantages of fixed search pattern and spatial correlation search pattern. Compared to the popular diamond search pattern, it has better performances.
This paper proposes an adaptive rood pattern search, a new fast block-matching motion estimation algorithm. It combines the advantages of fixed search pattern and spatial correlation search pattern. Compared to the popular diamond search pattern, it has better performances.
2005, 27(1): 108-111.
Abstract:
An improved scalable video coding scheme is proposed in this paper. The method generates the base layer including some sub-base layers by DCT coefficients reordering and VLC reshuffling, and the residues between the original DCT coefficients and the reconstructed DCT coefficients of the base layer are encoded in the enhancement layer with bit-plane coding technology. To transmit the layered streaming video generated by the proposed scheme over the IP network, an Adaptive Unequal Packet Loss Protect (AUPLP) strategy is designed to determine the current available network bandwidth and adjust sending rates according to different situation. Experimental results show that the proposed scheme can improve the average coding efficiency up to 1.2dB compared with conventional methods in low bandwidth, and the AUPLP strategy can further improve the performances of video network transmission system.
An improved scalable video coding scheme is proposed in this paper. The method generates the base layer including some sub-base layers by DCT coefficients reordering and VLC reshuffling, and the residues between the original DCT coefficients and the reconstructed DCT coefficients of the base layer are encoded in the enhancement layer with bit-plane coding technology. To transmit the layered streaming video generated by the proposed scheme over the IP network, an Adaptive Unequal Packet Loss Protect (AUPLP) strategy is designed to determine the current available network bandwidth and adjust sending rates according to different situation. Experimental results show that the proposed scheme can improve the average coding efficiency up to 1.2dB compared with conventional methods in low bandwidth, and the AUPLP strategy can further improve the performances of video network transmission system.
2005, 27(1): 112-115.
Abstract:
Current Internet video transmission is characterized mainly by variations in throughput and packet loss. Scalable Coding(SC) and Multiple Description Coding(MDC) have been proposed as source coding techniques that are robust to such channel problems. Studies showed that combination of the two approaches(MDSC) can guarantee better qualify adaptation video transmission. Traditional MDSC improves SC by introducing redundancy in base layer so that the chance of receiving at least one description of base layer is greatly enhanced. This idea is further expanded, and a new improved MDSC scheme is proposed in this paper. In the proposed approach, MDC is applied to the base layer of the first order SC, and then the derived descriptions are encoded by second order SCs. The advantage of this approach is that both the coding efficiency and robustness of the coding stream can be simultaneously considered.
Current Internet video transmission is characterized mainly by variations in throughput and packet loss. Scalable Coding(SC) and Multiple Description Coding(MDC) have been proposed as source coding techniques that are robust to such channel problems. Studies showed that combination of the two approaches(MDSC) can guarantee better qualify adaptation video transmission. Traditional MDSC improves SC by introducing redundancy in base layer so that the chance of receiving at least one description of base layer is greatly enhanced. This idea is further expanded, and a new improved MDSC scheme is proposed in this paper. In the proposed approach, MDC is applied to the base layer of the first order SC, and then the derived descriptions are encoded by second order SCs. The advantage of this approach is that both the coding efficiency and robustness of the coding stream can be simultaneously considered.
2005, 27(1): 116-118.
Abstract:
Taking the normal distribution as an example, this article discusses the problems of minimized entropy quantization in image compression, including single coefficient entropy quantization and multi-coefficients entropy quantization. It provides a quantization theory for different compression ratios.
Taking the normal distribution as an example, this article discusses the problems of minimized entropy quantization in image compression, including single coefficient entropy quantization and multi-coefficients entropy quantization. It provides a quantization theory for different compression ratios.
2005, 27(1): 119-122.
Abstract:
This paper generalizes the conclusion of Perfect nonlinear S-boxes by Nyberg(1991), and introduces the conception of inverse regular generalized vector Bent function. It shows that for inverse regular generalized vector Bent function f(m) with even variables, m is no more than half of?. It also shows that when the input dimension n is odd, the regular generalized vector Bent function and the inverse regular generalized vector Bent function do not exist. This may prevent the cryptology designer from seeking the inexistent function. A method for recursively constructing vector generalized Bent function is presented.
This paper generalizes the conclusion of Perfect nonlinear S-boxes by Nyberg(1991), and introduces the conception of inverse regular generalized vector Bent function. It shows that for inverse regular generalized vector Bent function f(m) with even variables, m is no more than half of?. It also shows that when the input dimension n is odd, the regular generalized vector Bent function and the inverse regular generalized vector Bent function do not exist. This may prevent the cryptology designer from seeking the inexistent function. A method for recursively constructing vector generalized Bent function is presented.
2005, 27(1): 123-126.
Abstract:
As DRR fails to provide strong latency bound, in this paper, a new scheduling discipline named Prioritized Nested DRR (PNDRR) is presented, which introduces a token bucket with virtual allocated token quantum and changes the entering order of the scheduling list for the latency-critical flow. By using the scheme for the latency critical flow, delay of packet in latency critical queue is effectively diminished. In this paper, theoretical analyses prove that PN DRR results in a significant improvement in the latency bound of delay-sensitive traffic in comparison to nested DRR(NDRR) while preserves the good properties as the same relative fairness bound and the per-packet complexity of 0(1) as NDRR. Simulation results also support analysis.
As DRR fails to provide strong latency bound, in this paper, a new scheduling discipline named Prioritized Nested DRR (PNDRR) is presented, which introduces a token bucket with virtual allocated token quantum and changes the entering order of the scheduling list for the latency-critical flow. By using the scheme for the latency critical flow, delay of packet in latency critical queue is effectively diminished. In this paper, theoretical analyses prove that PN DRR results in a significant improvement in the latency bound of delay-sensitive traffic in comparison to nested DRR(NDRR) while preserves the good properties as the same relative fairness bound and the per-packet complexity of 0(1) as NDRR. Simulation results also support analysis.
2005, 27(1): 127-130.
Abstract:
Research work on dynamic routing for traffic engineering is investigated. And an improved routing algorithm for optimizing network throughput is proposed. It is characterized by taking into account both network topology and traffic distribution condition, and putting forward graded link criticality with traffic engineering objectives translated into path constraints. Simulation results show the given algorithm outperforms Kodialams and the other several typical dynamic routing policies.
Research work on dynamic routing for traffic engineering is investigated. And an improved routing algorithm for optimizing network throughput is proposed. It is characterized by taking into account both network topology and traffic distribution condition, and putting forward graded link criticality with traffic engineering objectives translated into path constraints. Simulation results show the given algorithm outperforms Kodialams and the other several typical dynamic routing policies.
2005, 27(1): 131-135.
Abstract:
The basis of IEEE 802.11 wireless LAN Medium Access Control (MAC) is Distributed Coordination Function (DCF), When network load in WLAN is moderate or even higher, with DCF a station may need to defer several seconds before successful transmission. This will degrade the performance of real time applications such as MPEG-4 video stream. This paper proposes L-DCF, which is suit for real time applications, and presents mechanism for transmitting MPEG-4 video stream with L-DCF. Simulations show that this mechanism provides much less delay and jitter while obtains the same goodput and fairness.
The basis of IEEE 802.11 wireless LAN Medium Access Control (MAC) is Distributed Coordination Function (DCF), When network load in WLAN is moderate or even higher, with DCF a station may need to defer several seconds before successful transmission. This will degrade the performance of real time applications such as MPEG-4 video stream. This paper proposes L-DCF, which is suit for real time applications, and presents mechanism for transmitting MPEG-4 video stream with L-DCF. Simulations show that this mechanism provides much less delay and jitter while obtains the same goodput and fairness.
2005, 27(1): 136-138.
Abstract:
A theoretical model of Iterative Physical Optics (IPO) is established for the ElectroMagnetic (EM) scattering problem with imperfectly conducting boundaiy and applied to the analysis of EM scattering by a dielectric coated electrically large cavity. In each IPO iteration step, the total field on the dielectric surface is computed utilizing the Fresnel reflection coefficient. By employing iteration process, the EM field distribution on the inner wall of the cavity is predicted and then the scattering fields of the cavity are obtained. Numerical results demonstrate that the improved IPO algorithm is correct and effective for the analysis of dielectric coated electrically large targets.
A theoretical model of Iterative Physical Optics (IPO) is established for the ElectroMagnetic (EM) scattering problem with imperfectly conducting boundaiy and applied to the analysis of EM scattering by a dielectric coated electrically large cavity. In each IPO iteration step, the total field on the dielectric surface is computed utilizing the Fresnel reflection coefficient. By employing iteration process, the EM field distribution on the inner wall of the cavity is predicted and then the scattering fields of the cavity are obtained. Numerical results demonstrate that the improved IPO algorithm is correct and effective for the analysis of dielectric coated electrically large targets.
2005, 27(1): 139-142.
Abstract:
A coupling technique is proposed based on parametric yields centering design and tolerance optimization. The technique is convergence to the optimal normal values from given initial design variable and tolerance with little knowledge of circuit, device or technology. In the optimal value, the maximum yield can be obtained according to technology condition while proper technology conditions can be chosen according to practical requirements. Finally, the feasibility and utility of the method are demonstrated satisfactorily by numerical and practical examples.
A coupling technique is proposed based on parametric yields centering design and tolerance optimization. The technique is convergence to the optimal normal values from given initial design variable and tolerance with little knowledge of circuit, device or technology. In the optimal value, the maximum yield can be obtained according to technology condition while proper technology conditions can be chosen according to practical requirements. Finally, the feasibility and utility of the method are demonstrated satisfactorily by numerical and practical examples.
2005, 27(1): 143-145.
Abstract:
A new robust adaptive identification-based control of chaotic system with uncertain parameters in view of modeling error is proposed in this paper. The objective is to adjust the unknown chaos to a fixed point. It is fulfilled by taking following two steps: a dynamical neural network is used as system identifier, then a controller based on identification estimates is established to direct the chaos states towards desired target. Also, rigorous mathematical proof is given to analyze the stability properties of the system. Finally, the effectiveness of the proposed method is demonstrated by the Duffing equation.
A new robust adaptive identification-based control of chaotic system with uncertain parameters in view of modeling error is proposed in this paper. The objective is to adjust the unknown chaos to a fixed point. It is fulfilled by taking following two steps: a dynamical neural network is used as system identifier, then a controller based on identification estimates is established to direct the chaos states towards desired target. Also, rigorous mathematical proof is given to analyze the stability properties of the system. Finally, the effectiveness of the proposed method is demonstrated by the Duffing equation.
2005, 27(1): 150-152.
Abstract:
Through simulation this paper studies the performance of the system of V-BLAST combined with turbo code. The current methods process the V-BLAST algorithm and turbo decode algorithm independently. So it does not utilize the soft information of the received signal sufficiently. By simulation a novel method is presented. Through the combination of these two algorithms the complexity of the system realization does not increase, but the performance improves obviously.
Through simulation this paper studies the performance of the system of V-BLAST combined with turbo code. The current methods process the V-BLAST algorithm and turbo decode algorithm independently. So it does not utilize the soft information of the received signal sufficiently. By simulation a novel method is presented. Through the combination of these two algorithms the complexity of the system realization does not increase, but the performance improves obviously.
2005, 27(1): 153-154.
Abstract:
A new fast Kalman filtering algorithm is illustrated in detail. For some filtering courses whose coefficients can not be caculated offline, this way offers high work speed and has certain accuracy, at the same time, it takes less resource. The idea is tested with simulated tracking data.
A new fast Kalman filtering algorithm is illustrated in detail. For some filtering courses whose coefficients can not be caculated offline, this way offers high work speed and has certain accuracy, at the same time, it takes less resource. The idea is tested with simulated tracking data.
2005, 27(1): 155-157.
Abstract:
Although using pipelining structure in the hardware implementation can generally provide higher throughput, the application of this structure in current cryptography is limited, because they are not suitable for most common feedback modes. This paper puts forward a design of the hybrid pipelining architecture of AES. By including in the AES standard interleaved modes of operation, the design successfully implements the algorithm, which operates in the CBC mode. In this design, four data blocks can be dealt with in parallel (called one-encryption or one-decryption), and at the same time two encryptions or decryptions can be partially overlapped. The design has been implemented on EP20k300EBC652-l device (Ateral).
Although using pipelining structure in the hardware implementation can generally provide higher throughput, the application of this structure in current cryptography is limited, because they are not suitable for most common feedback modes. This paper puts forward a design of the hybrid pipelining architecture of AES. By including in the AES standard interleaved modes of operation, the design successfully implements the algorithm, which operates in the CBC mode. In this design, four data blocks can be dealt with in parallel (called one-encryption or one-decryption), and at the same time two encryptions or decryptions can be partially overlapped. The design has been implemented on EP20k300EBC652-l device (Ateral).
2005, 27(1): 158-160.
Abstract:
In this paper, an auto-verification platform for schematic design is presented based on the extended TCL as a script language. Using the extensible property of the TCL, constructed a set of extended TCL command on the general data structure of the schematic design, and on this base, a rule library and an auto-verification runner are built to make the auto verification of the schematic design possible.
In this paper, an auto-verification platform for schematic design is presented based on the extended TCL as a script language. Using the extensible property of the TCL, constructed a set of extended TCL command on the general data structure of the schematic design, and on this base, a rule library and an auto-verification runner are built to make the auto verification of the schematic design possible.
2005, 27(1): 146-149.
Abstract:
Framework of distributed cryptography is presented based on its development and relations among its branches. A systematical model of distributed cryptography is described at the same time. And researching content of distributed cryptography is reviewed based on researching principles of cryptography and status of distributed cryptography.
Framework of distributed cryptography is presented based on its development and relations among its branches. A systematical model of distributed cryptography is described at the same time. And researching content of distributed cryptography is reviewed based on researching principles of cryptography and status of distributed cryptography.
