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2008 Vol. 30, No. 12
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2008, 30(12): 2795-2799.
doi: 10.3724/SP.J.1146.2007.01974
Abstract:
In this paper, an improved baseline estimation approach based on the Fourier analysis of the interferometric phases is presented. Four improvements are made: a precise method to calculate the instant phase frequency is given; the rule of distributing the interferogram samples is given to improve the ill condition of the equations of least square method; a quantitative criterion of choosing the interfrogram samples is presented which can exclude the influences of interferograms corresponding to areas of low correlation or strong topography variations; an iterative scheme based on the differential interferometric phases is given. The improved approach is used in the processing of the airborne dual-antenna and repeat-pass InSAR data. The results validate that the improved approach is more accurate and robust than the original one. This improved approach is suit for the baseline estimation of the airborne repeat-pass InSAR data.
In this paper, an improved baseline estimation approach based on the Fourier analysis of the interferometric phases is presented. Four improvements are made: a precise method to calculate the instant phase frequency is given; the rule of distributing the interferogram samples is given to improve the ill condition of the equations of least square method; a quantitative criterion of choosing the interfrogram samples is presented which can exclude the influences of interferograms corresponding to areas of low correlation or strong topography variations; an iterative scheme based on the differential interferometric phases is given. The improved approach is used in the processing of the airborne dual-antenna and repeat-pass InSAR data. The results validate that the improved approach is more accurate and robust than the original one. This improved approach is suit for the baseline estimation of the airborne repeat-pass InSAR data.
2008, 30(12): 2800-2804.
doi: 10.3724/SP.J.1146.2007.00810
Abstract:
The bistatic configuration, when transmitter and receiver move along nonparallel tracks with unequal velocities, is called the general bistatic Synthetic Aperture Radar (SAR). This kind of bistatic SAR system has the potential for various applications. In this paper, it is shown that, for the general bistatic SAR with a long baseline, it is hard to convert the bistatic SAR data into a monostatic one for which the monostatic processor can be employed. Then, a Range Migration Algorithm (RMA) based on series reversion and numerical computation is presented. Finally, the accuracy of the proposed approach is verified with a simulation. The analysis and the simulation result show that this algorithm can be applied to the general bistatic case with a long baseline and a high squint angle.
The bistatic configuration, when transmitter and receiver move along nonparallel tracks with unequal velocities, is called the general bistatic Synthetic Aperture Radar (SAR). This kind of bistatic SAR system has the potential for various applications. In this paper, it is shown that, for the general bistatic SAR with a long baseline, it is hard to convert the bistatic SAR data into a monostatic one for which the monostatic processor can be employed. Then, a Range Migration Algorithm (RMA) based on series reversion and numerical computation is presented. Finally, the accuracy of the proposed approach is verified with a simulation. The analysis and the simulation result show that this algorithm can be applied to the general bistatic case with a long baseline and a high squint angle.
2008, 30(12): 2805-2808.
doi: 10.3724/SP.J.1146.2007.00916
Abstract:
Circular Trace Scanning Synthetic Aperture Radar (CTS-SAR) is a new operation mode radar, which can be used for wide observation. CTS-SAR have the characteristic of high time-space resolution, short repetition visit period and wide observation area. It can observe wide area in a short time with great efficiency for slow platform specially. The moving model and range model of CTS-SAR are advanced, and the Doppler characteristic and azimuth resolution characteristic of CTS-SAR are analyzed base on the above models. Then the imaging method of CTS-SAR is discussed. The computer simulation results validate the analyzed conclusions and the imaging method. CTS-SAR is competent for wide observation.
Circular Trace Scanning Synthetic Aperture Radar (CTS-SAR) is a new operation mode radar, which can be used for wide observation. CTS-SAR have the characteristic of high time-space resolution, short repetition visit period and wide observation area. It can observe wide area in a short time with great efficiency for slow platform specially. The moving model and range model of CTS-SAR are advanced, and the Doppler characteristic and azimuth resolution characteristic of CTS-SAR are analyzed base on the above models. Then the imaging method of CTS-SAR is discussed. The computer simulation results validate the analyzed conclusions and the imaging method. CTS-SAR is competent for wide observation.
2008, 30(12): 2809-2812.
doi: 10.3724/SP.J.1146.2007.01059
Abstract:
Based on the theory of scattering center, the difference of back-scattering characteristics between the mobile targets and natural terrains in high-resolution SAR imagery is investigated, and the principles of texture features of the two kind targets are discussed in this paper. And then, the texture features are extracted by using respectively the local statistics and fractal models, and the method of selecting the best features is presented. The real vehicle target SAR image data in MSTAR database are used to test the texture features, the best features are selected and the discriminating performances of those features are shown. The results show that those features are good and can be used to eliminate the most false alarms of natural terrains.
Based on the theory of scattering center, the difference of back-scattering characteristics between the mobile targets and natural terrains in high-resolution SAR imagery is investigated, and the principles of texture features of the two kind targets are discussed in this paper. And then, the texture features are extracted by using respectively the local statistics and fractal models, and the method of selecting the best features is presented. The real vehicle target SAR image data in MSTAR database are used to test the texture features, the best features are selected and the discriminating performances of those features are shown. The results show that those features are good and can be used to eliminate the most false alarms of natural terrains.
2008, 30(12): 2813-2817.
doi: 10.3724/SP.J.1146.2007.00894
Abstract:
To obtain the higher range resolution Inverse Synthetic Aperture Radar (ISAR) image, a method by combining the bandwidth of the Linearly Modulated Stepped Frequency (LMSF) radar signal in frequency domain is discussed. The model of high speed moving targets is proposed. In order to estimate the target motion parameters accurately, the method employing envelop alignment and Doppler center estimation is provided to fit the track of moving target. Based on the characteristic of target echo in ISAR, the original method of Doppler center estimation is ameliorated to increase the motion parameter estimation precision. Finally, the processing scheme is proposed, and the simulation results show that the method is effective.
To obtain the higher range resolution Inverse Synthetic Aperture Radar (ISAR) image, a method by combining the bandwidth of the Linearly Modulated Stepped Frequency (LMSF) radar signal in frequency domain is discussed. The model of high speed moving targets is proposed. In order to estimate the target motion parameters accurately, the method employing envelop alignment and Doppler center estimation is provided to fit the track of moving target. Based on the characteristic of target echo in ISAR, the original method of Doppler center estimation is ameliorated to increase the motion parameter estimation precision. Finally, the processing scheme is proposed, and the simulation results show that the method is effective.
2008, 30(12): 2818-2821.
doi: 10.3724/SP.J.1146.2007.00920
Abstract:
This paper presents an algorithm about SAR image matching based on target detection．According to the characteristics of SAR image, this method detects the strong scatterer targets firstly，and then calculates the centroid points of the strong scatterers targets, then these centroid points are used to generating Delaunay triangulation, After triangulation，in the centroids, incenters, circumcenters of the corresponding similar triangle for establishing the maping function between master-image and slave-image. Finally, the test carried out with SAR images of ERS-I, ERS-II satellite, compareing with the methods based on correlation, the experimental result confirms the effectiveness of this method.
This paper presents an algorithm about SAR image matching based on target detection．According to the characteristics of SAR image, this method detects the strong scatterer targets firstly，and then calculates the centroid points of the strong scatterers targets, then these centroid points are used to generating Delaunay triangulation, After triangulation，in the centroids, incenters, circumcenters of the corresponding similar triangle for establishing the maping function between master-image and slave-image. Finally, the test carried out with SAR images of ERS-I, ERS-II satellite, compareing with the methods based on correlation, the experimental result confirms the effectiveness of this method.
2008, 30(12): 2822-2826.
doi: 10.3724/SP.J.1146.2007.00928
Abstract:
A novel iterative algorithm to estimate the hidden states of wavelet coefficients of SAR images is proposed by combing the Hidden Markov Tree (HMT) and the Hidden Markov Random Field (HMRF) model. Inter-scale and intra-scale correlation of the coefficients are utilized efficiently in the new approach so the estimation for states is more accurate. With states known the Bayesian estimation is applied to the coefficients to eliminate noises infection. Experiments show that not only the image is despeckled efficiently but also the details are preserved well.
A novel iterative algorithm to estimate the hidden states of wavelet coefficients of SAR images is proposed by combing the Hidden Markov Tree (HMT) and the Hidden Markov Random Field (HMRF) model. Inter-scale and intra-scale correlation of the coefficients are utilized efficiently in the new approach so the estimation for states is more accurate. With states known the Bayesian estimation is applied to the coefficients to eliminate noises infection. Experiments show that not only the image is despeckled efficiently but also the details are preserved well.
2008, 30(12): 2827-2830.
doi: 10.3724/SP.J.1146.2007.00950
Abstract:
For improving the estimated precision and rationality of the scattering coherency matrixes of the class center of different terrain types among the unsupervised classification based on polarimetric target decomposition and the maximum likelihood classifier based on the complex Wishart distribution, a new method for unsupervised classification of terrain types is proposed in this paper. Through weighted-based calculating coherency matrix of the center of every class, the coherency matrix can better represent the class center because the method well considers the correlation of pixels and the texture information of SAR image. The algorithm is described in detail and the contrastive experiment is done using AIRSAR L band polarimetric images. The experiment result indicates that the classifications accuracy of the method is higher and the iterative speed is faster.
For improving the estimated precision and rationality of the scattering coherency matrixes of the class center of different terrain types among the unsupervised classification based on polarimetric target decomposition and the maximum likelihood classifier based on the complex Wishart distribution, a new method for unsupervised classification of terrain types is proposed in this paper. Through weighted-based calculating coherency matrix of the center of every class, the coherency matrix can better represent the class center because the method well considers the correlation of pixels and the texture information of SAR image. The algorithm is described in detail and the contrastive experiment is done using AIRSAR L band polarimetric images. The experiment result indicates that the classifications accuracy of the method is higher and the iterative speed is faster.
2008, 30(12): 2831-2834.
doi: 10.3724/SP.J.1146.2007.00923
Abstract:
This paper investigates the clutter suppression problem of airborne multi-channel SAR-GMTI system. A key problem for ground moving target indication is clutter suppression, which is sensitive to the correlation of channels. For the multi-channel system, there are differences among the characteristic of two channels and also the antenna patterns, which worse the correlation of channels. This paper proposes a channel equalization method and an adaptive clutter canceling method to improve the clutter suppression ratio. Theoretical results are evaluated and illustrated with experimental airborne SAR data.
This paper investigates the clutter suppression problem of airborne multi-channel SAR-GMTI system. A key problem for ground moving target indication is clutter suppression, which is sensitive to the correlation of channels. For the multi-channel system, there are differences among the characteristic of two channels and also the antenna patterns, which worse the correlation of channels. This paper proposes a channel equalization method and an adaptive clutter canceling method to improve the clutter suppression ratio. Theoretical results are evaluated and illustrated with experimental airborne SAR data.
2008, 30(12): 2835-2839.
doi: 10.3724/SP.J.1146.2007.00919
Abstract:
The imaging of ship targets is an active area in ISAR research field. Its key is to obtain the valuable side view and top view ship images. In this paper, by measuring the Doppler spreads and the centerline slopes of the ship from a sequence of sub-images generated with successive short time data, the variations of the resultant effective rotation vector and its vertical component are estimated. Subsequently, the sea state and the rock intensity of the ship are evaluated according to the two estimated rotation vectors, and the imaging processing is separate into several different cases. In each case, the imaging instants for ship side view and top view are determined. At the same time, the optimal duration centered with the chosen instant is searched by minimizing the image entropy. Simulated data and real data verify the effectiveness and practicability of the method. The ship top view or side view image can be obtained under unknown sea state, which much benefits the subsequent ship identification.
The imaging of ship targets is an active area in ISAR research field. Its key is to obtain the valuable side view and top view ship images. In this paper, by measuring the Doppler spreads and the centerline slopes of the ship from a sequence of sub-images generated with successive short time data, the variations of the resultant effective rotation vector and its vertical component are estimated. Subsequently, the sea state and the rock intensity of the ship are evaluated according to the two estimated rotation vectors, and the imaging processing is separate into several different cases. In each case, the imaging instants for ship side view and top view are determined. At the same time, the optimal duration centered with the chosen instant is searched by minimizing the image entropy. Simulated data and real data verify the effectiveness and practicability of the method. The ship top view or side view image can be obtained under unknown sea state, which much benefits the subsequent ship identification.
2008, 30(12): 2840-2843.
doi: 10.3724/SP.J.1146.2007.01375
Abstract:
In order to develop bistatic SAR ocean investigation, the first issue is the study of bistatic SAR ocean surface imaging mechanism. And velocity bunching mechanism is a SAR inherent modulation. Thus, the intensity expression in the bistatic SAR image plane is derived in this paper. The expression describes quantificationally the displacement of the scatter elements in the image plane and a degradation in radar resolution in azimuthal direction. In addition, a bistatic SAR linear velocity bunching transfer function is obtained in the linear parameter regime. Finally, this paper analyzes qualitatively the effects that various platform observation conditions have on the bistatic SAR linear imaging range of wave spectrum.
In order to develop bistatic SAR ocean investigation, the first issue is the study of bistatic SAR ocean surface imaging mechanism. And velocity bunching mechanism is a SAR inherent modulation. Thus, the intensity expression in the bistatic SAR image plane is derived in this paper. The expression describes quantificationally the displacement of the scatter elements in the image plane and a degradation in radar resolution in azimuthal direction. In addition, a bistatic SAR linear velocity bunching transfer function is obtained in the linear parameter regime. Finally, this paper analyzes qualitatively the effects that various platform observation conditions have on the bistatic SAR linear imaging range of wave spectrum.
2008, 30(12): 2844-2848.
doi: 10.3724/SP.J.1146.2007.00946
Abstract:
To solve the detection problem of high-speed accelerating targets in LFMCW (Linear Frequency- Modulated Continuous Wave) radar, a secondary mixing combined DPT (Discrete Polynomial-phase Transform) method is proposed. Utilizing the modulation symmetry of tri-LFMCW signals, up-sweep beat signal is secondary mixed with down-sweep one to eliminate MTRC (Migration Through Range Cell) induced by the high-speed. And DPT processing in terms of range cell leads to the estimation of acceleration and initial velocity. Furthermore, parameter estimation of multi-targets is emphasized. By analyzing the characteristics of the cross terms, the conditions for first order cross terms forming effective interfere and for second order cross terms emerging are derived, respectively. Resorting to Clean algorithm, multi-targets can be dealt with successfully, which detects and removes the strongest target for the current time. Processing steps of multi-targets cases are given. Simulation results testify the effectiveness of the method and the conclusions.
To solve the detection problem of high-speed accelerating targets in LFMCW (Linear Frequency- Modulated Continuous Wave) radar, a secondary mixing combined DPT (Discrete Polynomial-phase Transform) method is proposed. Utilizing the modulation symmetry of tri-LFMCW signals, up-sweep beat signal is secondary mixed with down-sweep one to eliminate MTRC (Migration Through Range Cell) induced by the high-speed. And DPT processing in terms of range cell leads to the estimation of acceleration and initial velocity. Furthermore, parameter estimation of multi-targets is emphasized. By analyzing the characteristics of the cross terms, the conditions for first order cross terms forming effective interfere and for second order cross terms emerging are derived, respectively. Resorting to Clean algorithm, multi-targets can be dealt with successfully, which detects and removes the strongest target for the current time. Processing steps of multi-targets cases are given. Simulation results testify the effectiveness of the method and the conclusions.
2008, 30(12): 2849-2853.
doi: 10.3724/SP.J.1146.2007.00803
Abstract:
In this paper, the ballistic trajectory model of cone-shaped spatial target is introduced. The RCS expression versus cosine of the aspect angle is derived based on the aspect angle expression of a precession target. The frequency transmission characteristic of RCS versus cosine of the aspect angle and the frequency characteristic of cosine of the aspect angle are analyzed. The frequency characteristic of RCS sequence is presented. Then a new method of estimating the precession cycle using the frequency characteristic is presented. Finally, a simulation result shows that the algorithm is effective.
In this paper, the ballistic trajectory model of cone-shaped spatial target is introduced. The RCS expression versus cosine of the aspect angle is derived based on the aspect angle expression of a precession target. The frequency transmission characteristic of RCS versus cosine of the aspect angle and the frequency characteristic of cosine of the aspect angle are analyzed. The frequency characteristic of RCS sequence is presented. Then a new method of estimating the precession cycle using the frequency characteristic is presented. Finally, a simulation result shows that the algorithm is effective.
2008, 30(12): 2854-2857.
doi: 10.3724/SP.J.1146.2007.00903
Abstract:
In this paper, a new criterion which is based on the statistical distinction to evaluate SAR jamming effect is proposed, according to the difference of the jamming signal with the target signal. Recurring to Independent Component Analysis (ICA) method, the jamming remove issue can be translated into the blind separation problem. The white noise jamming and clutter jamming SAR images is used as the input to the ICA algorithm respectively, and make use of kurtosis to classify the basis images which span into two different signal subspaces. Because of the clutter jamming signal is similar to the target returned signal on the statistical characteristic, the effect on the jamming remove is degraded contrasted to the white noise jamming. Theory analysis and simulation validate that the jamming method based on the target signal characteristic is availability.
In this paper, a new criterion which is based on the statistical distinction to evaluate SAR jamming effect is proposed, according to the difference of the jamming signal with the target signal. Recurring to Independent Component Analysis (ICA) method, the jamming remove issue can be translated into the blind separation problem. The white noise jamming and clutter jamming SAR images is used as the input to the ICA algorithm respectively, and make use of kurtosis to classify the basis images which span into two different signal subspaces. Because of the clutter jamming signal is similar to the target returned signal on the statistical characteristic, the effect on the jamming remove is degraded contrasted to the white noise jamming. Theory analysis and simulation validate that the jamming method based on the target signal characteristic is availability.
2008, 30(12): 2858-2861.
doi: 10.3724/SP.J.1146.2007.01220
Abstract:
For vegetation parameter inversion, the single baseline polarimetric SAR interferometry technique, such as the three-stage method and the ESPRIT algorithm, is limited by the observed data with the minimum ground to volume amplitude ratio, which effects the estimation of the effective phase center for the vegetation canopy or the surface, and thus results in the underestimated vegetation height. In order to remove this defect of the single baseline inversion techniques in some extend, another baseline polarimetric SAR interferometry data is added on vegetation parameter estimation in this paper, and a dual baseline polarimetric SAR interferometry technique for the extraction of the vegetation parameter is investigated and improved to reduce the dynamic bias for the vegetation parameter estimation. Finally, the simulated data and real data are used to validate this dual baseline technique.
For vegetation parameter inversion, the single baseline polarimetric SAR interferometry technique, such as the three-stage method and the ESPRIT algorithm, is limited by the observed data with the minimum ground to volume amplitude ratio, which effects the estimation of the effective phase center for the vegetation canopy or the surface, and thus results in the underestimated vegetation height. In order to remove this defect of the single baseline inversion techniques in some extend, another baseline polarimetric SAR interferometry data is added on vegetation parameter estimation in this paper, and a dual baseline polarimetric SAR interferometry technique for the extraction of the vegetation parameter is investigated and improved to reduce the dynamic bias for the vegetation parameter estimation. Finally, the simulated data and real data are used to validate this dual baseline technique.
2008, 30(12): 2862-2866.
doi: 10.3724/SP.J.1146.2007.00823
Abstract:
In this paper, a variational level set approach for segmentation of Regions Of Interest (ROI) is presented. Following the analysis of the SAR image characteristic, a new energy functional is defined by importing the statistical model of speckle noise. The energy functional is with respect to level set function, which is obviously different from the energy functional with respect to parameterized curve in general level set approach. The segmentation of ROI is implemented by the numerical solution of the Partial Difference Equations (PDEs) that are derived by minimizing the energy formulation. The performance of the approach is verified by both synthetic and real SAR images. It shows that the approach has the advantage of importing the noise information in the energy definition, thus accurately extracting the ROI from SAR image but without any speckle pre-processing step.
In this paper, a variational level set approach for segmentation of Regions Of Interest (ROI) is presented. Following the analysis of the SAR image characteristic, a new energy functional is defined by importing the statistical model of speckle noise. The energy functional is with respect to level set function, which is obviously different from the energy functional with respect to parameterized curve in general level set approach. The segmentation of ROI is implemented by the numerical solution of the Partial Difference Equations (PDEs) that are derived by minimizing the energy formulation. The performance of the approach is verified by both synthetic and real SAR images. It shows that the approach has the advantage of importing the noise information in the energy definition, thus accurately extracting the ROI from SAR image but without any speckle pre-processing step.
2008, 30(12): 2867-2870.
doi: 10.3724/SP.J.1146.2008.00414
Abstract:
This paper proposes a new method for automatic building recognition and mapping in remote sensing images. The method calculates the multiple feature of building first, and then selects the best feature list with PCA algorithm to segment the imagery into two kind of area, which contain building targets and does not contain. Finally, a method combined both the dominant direction and area factor is used to reconstruct the target buildings into regular polygons. The experimental results prove that this new method has a good precision and robustness.
This paper proposes a new method for automatic building recognition and mapping in remote sensing images. The method calculates the multiple feature of building first, and then selects the best feature list with PCA algorithm to segment the imagery into two kind of area, which contain building targets and does not contain. Finally, a method combined both the dominant direction and area factor is used to reconstruct the target buildings into regular polygons. The experimental results prove that this new method has a good precision and robustness.
2008, 30(12): 2871-2875.
doi: 10.3724/SP.J.1146.2007.00947
Abstract:
To tackle the problem of tracking a maneuvering emitter by a single passive observer, an algorithm of combining the Central Difference Filter(CDF) and Interacting Multiple-Model(IMM) method is proposed. The proposed algorithm is easy to implement due to no request of calculating the Jacobian matrix, and more numerical stable by rebuilding traditional IMM algorithm into square root form. The proposed algorithm is applied to single observer passive location by using radial acceleration and angle information. Computer simulation results show that the presented method has similar performance to UT based IMM, and better performance than EKF based IMM in tracking accuracy.
To tackle the problem of tracking a maneuvering emitter by a single passive observer, an algorithm of combining the Central Difference Filter(CDF) and Interacting Multiple-Model(IMM) method is proposed. The proposed algorithm is easy to implement due to no request of calculating the Jacobian matrix, and more numerical stable by rebuilding traditional IMM algorithm into square root form. The proposed algorithm is applied to single observer passive location by using radial acceleration and angle information. Computer simulation results show that the presented method has similar performance to UT based IMM, and better performance than EKF based IMM in tracking accuracy.
2008, 30(12): 2876-2880.
doi: 10.3724/SP.J.1146.2007.00939
Abstract:
In this paper, a new scheme based on multi-scale is presented to match multi-modal images, in the airborne autonomous navigation system. Pyramid structure is exploited，in the scheme from coarse to fine. In the coarsest scale, a stepwise elimination scheme is introduced, the Edge Dilatation Template (EDT) is presented and some methods are introduced to reduce the calculation. In the middle scales, Hausdorff Distance (HD) is exploited as similar measure. In the finest scale, mutual variance is exploited. Some methods are also introduced and deduced to speed up the calculation in other matching scales besides the finest scale. The results of the experiments indicate that the multi-scale method can achieve fast, precision matching between multi-modal images. It can be realized by hardware easily and helps to the engineering realization of image matching navigation system.
In this paper, a new scheme based on multi-scale is presented to match multi-modal images, in the airborne autonomous navigation system. Pyramid structure is exploited，in the scheme from coarse to fine. In the coarsest scale, a stepwise elimination scheme is introduced, the Edge Dilatation Template (EDT) is presented and some methods are introduced to reduce the calculation. In the middle scales, Hausdorff Distance (HD) is exploited as similar measure. In the finest scale, mutual variance is exploited. Some methods are also introduced and deduced to speed up the calculation in other matching scales besides the finest scale. The results of the experiments indicate that the multi-scale method can achieve fast, precision matching between multi-modal images. It can be realized by hardware easily and helps to the engineering realization of image matching navigation system.
2008, 30(12): 2881-2885.
doi: 10.3724/SP.J.1146.2007.01855
Abstract:
This paper discusses some redundancy steps of FRFT in signal detection based on the decomposition of FRFT, and puts forward a Reduced FRFT (RFRFT) algorithm. Then it discusses several important characters of RFRFT in detail. Combined with the phase difference method, it proposes the product RFRFT arithmetic to realize the Instantaneous Frequency Rate (IFR) estimation of mc-PPS. And it enhances the parameter resolution rate of RFRFT by angle transform. This method is easy to calculate and implement. Simulation results validate the method is able to suppress the noise and cross-terms, and can apply to low SNR environment.
This paper discusses some redundancy steps of FRFT in signal detection based on the decomposition of FRFT, and puts forward a Reduced FRFT (RFRFT) algorithm. Then it discusses several important characters of RFRFT in detail. Combined with the phase difference method, it proposes the product RFRFT arithmetic to realize the Instantaneous Frequency Rate (IFR) estimation of mc-PPS. And it enhances the parameter resolution rate of RFRFT by angle transform. This method is easy to calculate and implement. Simulation results validate the method is able to suppress the noise and cross-terms, and can apply to low SNR environment.
2008, 30(12): 2886-2889.
doi: 10.3724/SP.J.1146.2007.00804
Abstract:
In this paper, a Voice Activity Detection algorithm is developed, which uses a distance measure parameter parallel connection distance of probability density to improve detection. The algorithm is based on the determination of the speech/noise divergence by means of parallel distance of the Mel-field sub-band log-energies probability density. The proposed VAD is tested on speech signals with various noises under different SNRs. Experimental results show that the proposed VAD outperforms the standard algorithm G.729 VAD.
In this paper, a Voice Activity Detection algorithm is developed, which uses a distance measure parameter parallel connection distance of probability density to improve detection. The algorithm is based on the determination of the speech/noise divergence by means of parallel distance of the Mel-field sub-band log-energies probability density. The proposed VAD is tested on speech signals with various noises under different SNRs. Experimental results show that the proposed VAD outperforms the standard algorithm G.729 VAD.
2008, 30(12): 2890-2893.
doi: 10.3724/SP.J.1146.2007.01871
Abstract:
In this paper, the implement process and application in image processing of bidimensinal EMD are given. Two interpolation methods are analyed and comperad in arithmetic speed and visual efficiency with experiments and theory, Delaunay triangulation based cubic spline interpolation and radial basis function interpolation which are usually used.At the same time, a new fast decomposition based on radial basis function interpolation is suggested. Its superiorities are also analyzed. The results prove this method is feasible, and its superiorities are obvrious.
In this paper, the implement process and application in image processing of bidimensinal EMD are given. Two interpolation methods are analyed and comperad in arithmetic speed and visual efficiency with experiments and theory, Delaunay triangulation based cubic spline interpolation and radial basis function interpolation which are usually used.At the same time, a new fast decomposition based on radial basis function interpolation is suggested. Its superiorities are also analyzed. The results prove this method is feasible, and its superiorities are obvrious.
2008, 30(12): 2894-2897.
doi: 10.3724/SP.J.1146.2007.00973
Abstract:
The Finite Ridgelet Transform (FRIT) is a new image processing method which could conquer the defect of Wavelet in high dimension. The method changes the line singularity in the image into the point singularity via the Radon transform, deals the point singularity with Wavelet transform. It is shown that the energy is compact by using the Radon transform on the image, and the characteristic on the Ridgelet transform is applied in the image processing which obtains the good result in the denoising and the edge keeping of the image. Especially under the strong noisy, it is better than other methods.
The Finite Ridgelet Transform (FRIT) is a new image processing method which could conquer the defect of Wavelet in high dimension. The method changes the line singularity in the image into the point singularity via the Radon transform, deals the point singularity with Wavelet transform. It is shown that the energy is compact by using the Radon transform on the image, and the characteristic on the Ridgelet transform is applied in the image processing which obtains the good result in the denoising and the edge keeping of the image. Especially under the strong noisy, it is better than other methods.
2008, 30(12): 2898-2901.
doi: 10.3724/SP.J.1146.2007.00951
Abstract:
In image local elastic transformation, compact support radial basis functions are used to implement local elastic deformation transformation. The elastic deformation area is related to the support of radial basis function. However, how to choose the support size of the radial basis function based on space distribution of landmarks still is an unresolved doubt. In this paper, choosing the support of Wendland basis functions based on the space distribution of two landmarks is analyzed in detail. For the landmarks set, Delaunay triangle is constructed to obtain the optimal distance between landmarks, and support is chosen correspondingly. The principle of choosing the support size of radial basis functions in image local elastic transformation is given also. Experiments of the artificial images and medial images show the feasibility of this conclusion
In image local elastic transformation, compact support radial basis functions are used to implement local elastic deformation transformation. The elastic deformation area is related to the support of radial basis function. However, how to choose the support size of the radial basis function based on space distribution of landmarks still is an unresolved doubt. In this paper, choosing the support of Wendland basis functions based on the space distribution of two landmarks is analyzed in detail. For the landmarks set, Delaunay triangle is constructed to obtain the optimal distance between landmarks, and support is chosen correspondingly. The principle of choosing the support size of radial basis functions in image local elastic transformation is given also. Experiments of the artificial images and medial images show the feasibility of this conclusion
2008, 30(12): 2902-2905.
doi: 10.3724/SP.J.1146.2007.00864
Abstract:
A new supervised linear dimensionality reduction method called Discriminant Projection Embedding (DPE) is proposed. Compared with widely-used Linear Discriminant Analysis (LDA), DPE can preserve the within-class neighboring geometry and extract between-class relevant structures for classification more efficient. Experimental results on public face databases show the feasibility and efficiency of DPE.
A new supervised linear dimensionality reduction method called Discriminant Projection Embedding (DPE) is proposed. Compared with widely-used Linear Discriminant Analysis (LDA), DPE can preserve the within-class neighboring geometry and extract between-class relevant structures for classification more efficient. Experimental results on public face databases show the feasibility and efficiency of DPE.
2008, 30(12): 2906-2911.
doi: 10.3724/SP.J.1146.2007.00915
Abstract:
Asynchrony of speech and lip motion is a key issue of multi-model fusion Audio-Visual Speech Recognition (AVSR). In this paper, a Multi-Stream Asynchrony Dynamic Bayesian Network (MS-ADBN) model is introduced, which looses the asynchrony of audio and visual streams to the word level, and both in audio stream and in visual stream, word-phone topology structure is used. However, Multi-stream Multi-states Asynchrony DBN (MM-ADBN) model is an augmentation of Multi-Stream DBN (MS-ADBN) model, is proposed for large vocabulary AVSR, which adopts word-phone-state topology structure in both audio stream and visual stream. In essential, MS-ADBN model is a word model, and while MM-ADBN model is a phone model whose recognition basic units are phones. The experiments are done on small vocabulary and large vocabulary audio-visual database, the results show that: for large vocabulary audio-visual database, comparing with MS-ADBN model and MSHMM, in clean speech environment, the improvements of 35.91 and 9.97% are obtained for MM-ADBN model respectively, which show the asynchrony description is important for AVSR systems.
Asynchrony of speech and lip motion is a key issue of multi-model fusion Audio-Visual Speech Recognition (AVSR). In this paper, a Multi-Stream Asynchrony Dynamic Bayesian Network (MS-ADBN) model is introduced, which looses the asynchrony of audio and visual streams to the word level, and both in audio stream and in visual stream, word-phone topology structure is used. However, Multi-stream Multi-states Asynchrony DBN (MM-ADBN) model is an augmentation of Multi-Stream DBN (MS-ADBN) model, is proposed for large vocabulary AVSR, which adopts word-phone-state topology structure in both audio stream and visual stream. In essential, MS-ADBN model is a word model, and while MM-ADBN model is a phone model whose recognition basic units are phones. The experiments are done on small vocabulary and large vocabulary audio-visual database, the results show that: for large vocabulary audio-visual database, comparing with MS-ADBN model and MSHMM, in clean speech environment, the improvements of 35.91 and 9.97% are obtained for MM-ADBN model respectively, which show the asynchrony description is important for AVSR systems.
2008, 30(12): 2912-2915.
doi: 10.3724/SP.J.1146.2007.00817
Abstract:
Blind image restoration is to recover the original image form the observed degraded image with unknown the Point Spread Function (PSF). This paper proposes a blind image restoration algorithm iteratively using wavelet denoising and total variation regularization. The observation model is first divided into two mutually associated sub-models, and this representation converses the blind restoration into the two issues of image denoising and image restoration, which makes us to solve the problem by iteratively using image denoising and image restoration algorithms. The stage of the PSF identification uses Total Variation (TV) regularization and the stage of image restoration uses wavelet denoising and TV regularization. The experimental results show that the proposed algorithm achieves better performance than the existing algorithms.
Blind image restoration is to recover the original image form the observed degraded image with unknown the Point Spread Function (PSF). This paper proposes a blind image restoration algorithm iteratively using wavelet denoising and total variation regularization. The observation model is first divided into two mutually associated sub-models, and this representation converses the blind restoration into the two issues of image denoising and image restoration, which makes us to solve the problem by iteratively using image denoising and image restoration algorithms. The stage of the PSF identification uses Total Variation (TV) regularization and the stage of image restoration uses wavelet denoising and TV regularization. The experimental results show that the proposed algorithm achieves better performance than the existing algorithms.
2008, 30(12): 2916-2920.
doi: 10.3724/SP.J.1146.2007.00961
Abstract:
An effective segmentation and recognition method of Chinese handwritten address strings is proposed. Firstly, over-segmentation is applied to character string images by extracting stroke and merging them to obtain radical sequences. Next, the optimal segmentation and recognition result is achieved by synthesizing geometric analysis, isolated character classifier and semantic information together. The geometric information is estimated on current character string to adapt to various writing styles of character strings. The isolated character classifier adopts MQDF classifier with ten candidate results and their confidence. The semantic information is described by a character-based bi-gram model, parameters of which are estimated from a database containing 180,000 addresses items. The algorithm is tested on 3,000 actual handwritten address samples and the single-character recognition rate is 88.28%.
An effective segmentation and recognition method of Chinese handwritten address strings is proposed. Firstly, over-segmentation is applied to character string images by extracting stroke and merging them to obtain radical sequences. Next, the optimal segmentation and recognition result is achieved by synthesizing geometric analysis, isolated character classifier and semantic information together. The geometric information is estimated on current character string to adapt to various writing styles of character strings. The isolated character classifier adopts MQDF classifier with ten candidate results and their confidence. The semantic information is described by a character-based bi-gram model, parameters of which are estimated from a database containing 180,000 addresses items. The algorithm is tested on 3,000 actual handwritten address samples and the single-character recognition rate is 88.28%.
2008, 30(12): 2921-2925.
doi: 10.3724/SP.J.1146.2007.00876
Abstract:
Analyzing sentences selection in summarization, an approach based on deleting sentences in a sentences set to obtain summary is proposed, which differs from the traditional method of adding sentences to get the summary. It has two stages, one is the process of obtaining the candidate summary sentences set with direct obtaining algorithm and redundancy-based obtaining algorithm, the other is the process of deleting sentences with sentences optimum algorithm. With DUC 2004 as the test corpus, the ROUGE value of summaries gotten by sentences selection proves the necessity of sentences optimum selection for multi-document summarization. Compared with the redundancy-based sentences selection method, the validity of the approach proposed is proved.
Analyzing sentences selection in summarization, an approach based on deleting sentences in a sentences set to obtain summary is proposed, which differs from the traditional method of adding sentences to get the summary. It has two stages, one is the process of obtaining the candidate summary sentences set with direct obtaining algorithm and redundancy-based obtaining algorithm, the other is the process of deleting sentences with sentences optimum algorithm. With DUC 2004 as the test corpus, the ROUGE value of summaries gotten by sentences selection proves the necessity of sentences optimum selection for multi-document summarization. Compared with the redundancy-based sentences selection method, the validity of the approach proposed is proved.
2008, 30(12): 2926-2929.
doi: 10.3724/SP.J.1146.2007.00868
Abstract:
Word Sense Disambiguation (WSD) is one of the key issues and difficulties in natural language processing. WSD is usually considered as an issue about pattern classification to study, which feature selection, is an important component. In this paper, according to Nave Bayesian Model (NBM) assumption, a feature selection method based on information gain is proposed to improve NBM. Location information concealed in the context of ambiguous word is mined through information gain, to improve the knowledge acquisition efficiency of Bayesian model, thereby improving the word-sense classification. The eight ambiguous words are tested in the experiment. The experimental results show that improved Bayesian model is more correct than the NBM an average of 3.5 percentage points. The accuracy rise is bigger and the improvement effect is outstanding. These results prove also the method put forward in this paper is efficacious.
Word Sense Disambiguation (WSD) is one of the key issues and difficulties in natural language processing. WSD is usually considered as an issue about pattern classification to study, which feature selection, is an important component. In this paper, according to Nave Bayesian Model (NBM) assumption, a feature selection method based on information gain is proposed to improve NBM. Location information concealed in the context of ambiguous word is mined through information gain, to improve the knowledge acquisition efficiency of Bayesian model, thereby improving the word-sense classification. The eight ambiguous words are tested in the experiment. The experimental results show that improved Bayesian model is more correct than the NBM an average of 3.5 percentage points. The accuracy rise is bigger and the improvement effect is outstanding. These results prove also the method put forward in this paper is efficacious.
2008, 30(12): 2930-2933.
doi: 10.3724/SP.J.1146.2007.00800
Abstract:
A new method is presented in this paper for the calculation of waveguide invariant () with passive sonar lofargram image. The distributions of in two waveguides are studied with normal mode model. Concise formula for calculating is then derived by finding the 2-D Fourier transforms ridges of the lofargrams. The algorithm is exercised for a Pekeris waveguide and a simulated shallow water waveguide containing thermoclines with source depth varying from 10m to 90m. It then is applied to a lofargram collected during an experiment at the South China Sea. The result of experimental data is well matched to the simulations. The approach differs from normal mode algorithm by virtue of its avoidance of potentially prohibitive computation and accurate estimation of environmental parameters and is more suitable for real-time signal processing.
A new method is presented in this paper for the calculation of waveguide invariant () with passive sonar lofargram image. The distributions of in two waveguides are studied with normal mode model. Concise formula for calculating is then derived by finding the 2-D Fourier transforms ridges of the lofargrams. The algorithm is exercised for a Pekeris waveguide and a simulated shallow water waveguide containing thermoclines with source depth varying from 10m to 90m. It then is applied to a lofargram collected during an experiment at the South China Sea. The result of experimental data is well matched to the simulations. The approach differs from normal mode algorithm by virtue of its avoidance of potentially prohibitive computation and accurate estimation of environmental parameters and is more suitable for real-time signal processing.
2008, 30(12): 2934-2937.
doi: 10.3724/SP.J.1146.2007.00801
Abstract:
Unknown interference and noise are ubiquitous in the complexity multi-antennas environment. They not only reduce precision of signal detection in Multi-Input Multi-Output (MIMO) systems seriously but also make it difficult to obtain perfect Channel State Information (CSI). In this paper, to cancel unknown interference in MIMO systems, a new approach for modeling these systems with imperfect CSI is introduced. The interference is treated as a nonlinear function in the model and estimated based on nonparametric theory. Unlike other interference cancellation methods, the interference treated here is unknown absolutely. Furthermore, the proposed interference cancellation is proved to be effective via theoretical analysis. That is, estimation of the interference is convergent. Simulation results demonstrate that the interference cancellation proposed here is valid for MIMO systems with imperfect CSI.
Unknown interference and noise are ubiquitous in the complexity multi-antennas environment. They not only reduce precision of signal detection in Multi-Input Multi-Output (MIMO) systems seriously but also make it difficult to obtain perfect Channel State Information (CSI). In this paper, to cancel unknown interference in MIMO systems, a new approach for modeling these systems with imperfect CSI is introduced. The interference is treated as a nonlinear function in the model and estimated based on nonparametric theory. Unlike other interference cancellation methods, the interference treated here is unknown absolutely. Furthermore, the proposed interference cancellation is proved to be effective via theoretical analysis. That is, estimation of the interference is convergent. Simulation results demonstrate that the interference cancellation proposed here is valid for MIMO systems with imperfect CSI.
2008, 30(12): 2938-2942.
doi: 10.3724/SP.J.1146.2008.00137
Abstract:
A new fast decoding method of Quasi-Cyclic LDPC(QC-LDPC)codes, named semi-serial decoding algorithm, is presented through contraposing the shortcoming of flood decoding method.For the algorithm, the message was updated in a serial sequence of m subsets of check nodes(or variable nodes), while the check nodes(or variable nodes) in the same subset are updated simultaneously. In this way,the decoding speed would be faster than the common serial decoding algorithm several times. An efficient grouping method suitable for the quasi-cyclic LDPC codes based on the circulant architecture is proposed.Simulation results show that,under the same complexiry,the proposed algorithm fastens the decoding speed of quasi-cyclic LDPC codes, meanwhile, it inherits all the merits of the serial massage-passing decoding algorithm. The conclusion is that the speed of the semi-serial decoding method is at least p times than that of the serial one(p is the number of rows of the cyclic permutation matrix in the parity check matrix of quasi-cyclic LDPC codes).
A new fast decoding method of Quasi-Cyclic LDPC(QC-LDPC)codes, named semi-serial decoding algorithm, is presented through contraposing the shortcoming of flood decoding method.For the algorithm, the message was updated in a serial sequence of m subsets of check nodes(or variable nodes), while the check nodes(or variable nodes) in the same subset are updated simultaneously. In this way,the decoding speed would be faster than the common serial decoding algorithm several times. An efficient grouping method suitable for the quasi-cyclic LDPC codes based on the circulant architecture is proposed.Simulation results show that,under the same complexiry,the proposed algorithm fastens the decoding speed of quasi-cyclic LDPC codes, meanwhile, it inherits all the merits of the serial massage-passing decoding algorithm. The conclusion is that the speed of the semi-serial decoding method is at least p times than that of the serial one(p is the number of rows of the cyclic permutation matrix in the parity check matrix of quasi-cyclic LDPC codes).
2008, 30(12): 2943-2946.
doi: 10.3724/SP.J.1146.2007.00847
Abstract:
A sub-optimal resource allocation algorithm for broadcast/multicast OFDM system is presented in this paper. By proposed algorithm, the fairness and efficiency is improved based on taking the target rates of different services as Quality of Service (QoS) constraint and finding out the lowest rate in one service group for comparison in order that all users can get target QoS requirement. At the same time, the complexity of this algorithm is reduced by introduction of two-dimensional Frequency-Time Grid (FTG) scheme. Simulation results show that the efficiency of proposed allocation algorithm is obvious which has significant higher fairness and throughput being very close to the upper bound of optimum method.
A sub-optimal resource allocation algorithm for broadcast/multicast OFDM system is presented in this paper. By proposed algorithm, the fairness and efficiency is improved based on taking the target rates of different services as Quality of Service (QoS) constraint and finding out the lowest rate in one service group for comparison in order that all users can get target QoS requirement. At the same time, the complexity of this algorithm is reduced by introduction of two-dimensional Frequency-Time Grid (FTG) scheme. Simulation results show that the efficiency of proposed allocation algorithm is obvious which has significant higher fairness and throughput being very close to the upper bound of optimum method.
2008, 30(12): 2947-2950.
doi: 10.3724/SP.J.1146.2007.00844
Abstract:
A novel Block Iterative (BI) and Adaptive Block Iterative (ABI) based schemes of Partial Transmit Sequence (PTS) for Peak to Average Power Ratio (PAPR) reduction in Orthogonal Frequency-Division Multiplexing (OFDM) are proposed, which can effectively reduce the high PAPR caused by OFDM. Compared with the Original Partial Transmit Sequence (OPTS) and Iterative Flipping (IF) algorithm, the proposed schemes can obtain much better tradeoff between performance and complexity, and can be considered as the generalization of OPTS and IF algorithm.
A novel Block Iterative (BI) and Adaptive Block Iterative (ABI) based schemes of Partial Transmit Sequence (PTS) for Peak to Average Power Ratio (PAPR) reduction in Orthogonal Frequency-Division Multiplexing (OFDM) are proposed, which can effectively reduce the high PAPR caused by OFDM. Compared with the Original Partial Transmit Sequence (OPTS) and Iterative Flipping (IF) algorithm, the proposed schemes can obtain much better tradeoff between performance and complexity, and can be considered as the generalization of OPTS and IF algorithm.
2008, 30(12): 2951-2954.
doi: 10.3724/SP.J.1146.2007.00911
Abstract:
MIMO is a main capacity improving technique in wireless communication. In slowly fading channel MIMO receiver can feedback the Channel State Information (CSI) to transmitter for the purpose of improving system performance. Traditional feedback-precoding scheme Singular Value Decomposition (SVD) affected by spatial correlation and requirement of traditional VBLAST system about number of transmission and receive antennas, its application is severely restricted. This paper presents an adaptive MIMO transmission system, adopting uniform channel parameter feedback mode and Space-Time Block Code (STBC), this technique can overcome the drawbacks of SVD scheme mentioned above. The simulation results show this kind of system can work with receive antennas less than transmission antennas and perform well under high correlated channel.
MIMO is a main capacity improving technique in wireless communication. In slowly fading channel MIMO receiver can feedback the Channel State Information (CSI) to transmitter for the purpose of improving system performance. Traditional feedback-precoding scheme Singular Value Decomposition (SVD) affected by spatial correlation and requirement of traditional VBLAST system about number of transmission and receive antennas, its application is severely restricted. This paper presents an adaptive MIMO transmission system, adopting uniform channel parameter feedback mode and Space-Time Block Code (STBC), this technique can overcome the drawbacks of SVD scheme mentioned above. The simulation results show this kind of system can work with receive antennas less than transmission antennas and perform well under high correlated channel.
2008, 30(12): 2955-2958.
doi: 10.3724/SP.J.1146.2007.00857
Abstract:
A space-time double iterative Sequential Monte Carlo (SMC) sampling-based detection algorithm is proposed for flat fading MIMO channel，based on traditional algorithms which only focus on time sampling or space sampling. A space-time multidimensional integral is established to compute the signals probability. SMC samples are drawn from both space and time dimensions, and the integral numerical value is approximated by weighted samples. The time samples are also utilized to complete joint channel estimation. The simulation result indicates that the proposed algorithm can obtain the suboptimal performance by low computational complexity.
A space-time double iterative Sequential Monte Carlo (SMC) sampling-based detection algorithm is proposed for flat fading MIMO channel，based on traditional algorithms which only focus on time sampling or space sampling. A space-time multidimensional integral is established to compute the signals probability. SMC samples are drawn from both space and time dimensions, and the integral numerical value is approximated by weighted samples. The time samples are also utilized to complete joint channel estimation. The simulation result indicates that the proposed algorithm can obtain the suboptimal performance by low computational complexity.
2008, 30(12): 2959-2962.
doi: 10.3724/SP.J.1146.2007.00813
Abstract:
In this paper, a novel and simple simulation model for the generation of Rayleigh waveforms with various autocorrelation properties is proposed. Based on this model, the method for generating the Rayleigh fading waveforms in wireless channels is given. By using the model, an arbitrary number of independent Rayleigh fading waveforms can be easily generated, which is of great importance for realistic performance assessments of the frequency-diversity wireless communication systems. Simulation results show that the model can effectively generate the Rayleigh waveforms with small-scale channel characteristics, which satisfy the autocorrelation property and stationary requirement.
In this paper, a novel and simple simulation model for the generation of Rayleigh waveforms with various autocorrelation properties is proposed. Based on this model, the method for generating the Rayleigh fading waveforms in wireless channels is given. By using the model, an arbitrary number of independent Rayleigh fading waveforms can be easily generated, which is of great importance for realistic performance assessments of the frequency-diversity wireless communication systems. Simulation results show that the model can effectively generate the Rayleigh waveforms with small-scale channel characteristics, which satisfy the autocorrelation property and stationary requirement.
Nash Fairness Based Resource Allocation Algorithm for Dirty-Paper Coded Multi-user MIMO-OFDM Systems
2008, 30(12): 2963-2966.
doi: 10.3724/SP.J.1146.2007.00969
Abstract:
MIMO-OFDM has been one of the most promising techniques for high data rate wireless transmission. In multi-user systems, how to guarantee the fairness among users while achieving large system throughput is an important issue for practical system design. In this paper, the Dirty-Paper Coding (DPC) as a new transmission technique is investigated to achieve the large throughput of MIMO systems, and a novel resource allocation algorithm based on Nash fairness is proposed for dirty-paper coded multi-user MIMO-OFDM systems. Simulation results show that the proposed algorithm can provide fair resource allocation among users, with less overall system rate loss.
MIMO-OFDM has been one of the most promising techniques for high data rate wireless transmission. In multi-user systems, how to guarantee the fairness among users while achieving large system throughput is an important issue for practical system design. In this paper, the Dirty-Paper Coding (DPC) as a new transmission technique is investigated to achieve the large throughput of MIMO systems, and a novel resource allocation algorithm based on Nash fairness is proposed for dirty-paper coded multi-user MIMO-OFDM systems. Simulation results show that the proposed algorithm can provide fair resource allocation among users, with less overall system rate loss.
2008, 30(12): 2967-2971.
doi: 10.3724/SP.J.1146.2008.00383
Abstract:
A Differential Jamming Rejection (DJR) receiver in FFH/MFSK systems is introduced under a worst-case band multi-tone jamming. This method, based on ahead spectrum detection using apriority knowledge of FHP (Frequency Hopping Pattern) and FH rate, implements differential suppression of multi-tone jamming without any side information. Further analysis and data simulation indicate that this scheme possesses good efficiency.
A Differential Jamming Rejection (DJR) receiver in FFH/MFSK systems is introduced under a worst-case band multi-tone jamming. This method, based on ahead spectrum detection using apriority knowledge of FHP (Frequency Hopping Pattern) and FH rate, implements differential suppression of multi-tone jamming without any side information. Further analysis and data simulation indicate that this scheme possesses good efficiency.
2008, 30(12): 2972-2975.
doi: 10.3724/SP.J.1146.2007.01848
Abstract:
Dynamic resource allocation algorithms are investigated for downlink multiuser Multiple Input Multiple Output Orthogonal Frequency Division Multiple Access and Space Division Multiple Access (MIMO-OFDMA/SDMA) systems. Firstly, a mathematical formulation is provided with the goal of maximizing throughput under various constraints. Secondly, since the optimal solution is difficult to obtain, the optimization procedure is divided into two steps. In the first step, a metric is derived to measure the spatial compatibility of users with multiple antennas, and then a scheduling algorithm is developed based on the proposed metric. In the second step, two suboptimal algorithms are developed to assign resources for the scheduled users. Simulation results demonstrate that proposed algorithms outperform random scheduling scheme. When combined with power reuse strategy, proposed algorithms obtain performances close to the optimal scheme based on user selection.
Dynamic resource allocation algorithms are investigated for downlink multiuser Multiple Input Multiple Output Orthogonal Frequency Division Multiple Access and Space Division Multiple Access (MIMO-OFDMA/SDMA) systems. Firstly, a mathematical formulation is provided with the goal of maximizing throughput under various constraints. Secondly, since the optimal solution is difficult to obtain, the optimization procedure is divided into two steps. In the first step, a metric is derived to measure the spatial compatibility of users with multiple antennas, and then a scheduling algorithm is developed based on the proposed metric. In the second step, two suboptimal algorithms are developed to assign resources for the scheduled users. Simulation results demonstrate that proposed algorithms outperform random scheduling scheme. When combined with power reuse strategy, proposed algorithms obtain performances close to the optimal scheme based on user selection.
2008, 30(12): 2976-2979.
doi: 10.3724/SP.J.1146.2007.00822
Abstract:
A Minimum Output Energy (MOE) noise suppression linear conjugate multiuser detection algorithm based on Recursive Least-Squares (RLS) is proposed for MC-CDMA system. The proposed algorithm defines a new cost function based on the MOE criterion and uses the noise subspace to impose multiple constraints on the new defined MOE cost function. A noise suppression linear conjugate detector is designed by using the new defined cost function and the new constraints condition, and the RLS algorithm is used to obtain the weight vector adaptively. It makes orthogonal processing between the weight vector and the noise subspace to mitigate the noise in the weight vector, and exploits the information contained in the pseudoautocorrelation of the observables. Therefore the performance of the system is improved. Simulation results demonstrate the effectiveness and superiority of the proposed algorithm.
A Minimum Output Energy (MOE) noise suppression linear conjugate multiuser detection algorithm based on Recursive Least-Squares (RLS) is proposed for MC-CDMA system. The proposed algorithm defines a new cost function based on the MOE criterion and uses the noise subspace to impose multiple constraints on the new defined MOE cost function. A noise suppression linear conjugate detector is designed by using the new defined cost function and the new constraints condition, and the RLS algorithm is used to obtain the weight vector adaptively. It makes orthogonal processing between the weight vector and the noise subspace to mitigate the noise in the weight vector, and exploits the information contained in the pseudoautocorrelation of the observables. Therefore the performance of the system is improved. Simulation results demonstrate the effectiveness and superiority of the proposed algorithm.
2008, 30(12): 2980-2983.
doi: 10.3724/SP.J.1146.2008.00035
Abstract:
In the pseudo-target geometrical constraint method, which aims at location using single observer in NLOS environment, the area of the target feasible region has direct effect on the speed and accuracy of the location algorithm. An optimal path planning algorithm of the observer is proposed in this paper, which is based on the dynamic programming. Based on the data measured at the current stage, the optimal moving direction of the observer at the next stage is calculated aiming at the maximum area of the target feasible region convergence. The optimized maneuvering path calculated by the proposed algorithm can improve the location precision and reduce the location time.
In the pseudo-target geometrical constraint method, which aims at location using single observer in NLOS environment, the area of the target feasible region has direct effect on the speed and accuracy of the location algorithm. An optimal path planning algorithm of the observer is proposed in this paper, which is based on the dynamic programming. Based on the data measured at the current stage, the optimal moving direction of the observer at the next stage is calculated aiming at the maximum area of the target feasible region convergence. The optimized maneuvering path calculated by the proposed algorithm can improve the location precision and reduce the location time.
2008, 30(12): 2984-2986.
doi: 10.3724/SP.J.1146.2006.02096
Abstract:
Conventional Bell-labs Layered Space Time (BLAST) receivers based on ZF or MMSE algorithm are of great complexity which can not be utilized in the mobile. This paper proposed a transmitter design which combined BLAST and eigenbeamforming with multiple beams pointing to orthogonal directions along the eigenvectors of the channels correlation matrix, and with variable rate allocation under certain bit error rate requirement. In this technique, layered spacetime pre-processing at the transmitter with a simplified receiver at the mobile station requires only simple signal processing.
Conventional Bell-labs Layered Space Time (BLAST) receivers based on ZF or MMSE algorithm are of great complexity which can not be utilized in the mobile. This paper proposed a transmitter design which combined BLAST and eigenbeamforming with multiple beams pointing to orthogonal directions along the eigenvectors of the channels correlation matrix, and with variable rate allocation under certain bit error rate requirement. In this technique, layered spacetime pre-processing at the transmitter with a simplified receiver at the mobile station requires only simple signal processing.
2008, 30(12): 2987-2990.
doi: 10.3724/SP.J.1146.2007.00935
Abstract:
When the chaotic systems are divided into linear and nonlinear parts, a new approach is presented to realize generalized synchronization of chaotic systems, by using feedback control and parameter commutation. Based on linear transform, the question of generalized synchronization system can be transformed into the stability question of synchronous error system, and the existence condition of GS has been given. Furthermore, favorable performance of generalized synchronization can be improved according to configuration of GS velocity。Expansive generalization can be acquired, without a limit of stability of linear part of the chaotic system. The Lorenz system is taken for illustration and verification，and the results of the simulation indicated that the method is provided of favorable applicability.
When the chaotic systems are divided into linear and nonlinear parts, a new approach is presented to realize generalized synchronization of chaotic systems, by using feedback control and parameter commutation. Based on linear transform, the question of generalized synchronization system can be transformed into the stability question of synchronous error system, and the existence condition of GS has been given. Furthermore, favorable performance of generalized synchronization can be improved according to configuration of GS velocity。Expansive generalization can be acquired, without a limit of stability of linear part of the chaotic system. The Lorenz system is taken for illustration and verification，and the results of the simulation indicated that the method is provided of favorable applicability.
2008, 30(12): 2991-2995.
doi: 10.3724/SP.J.1146.2007.00907
Abstract:
In this paper, the multi-output plateaued functions are constructed by methods of affine transformation, concatenation, injective sets and the state transform matrix of m-sequences. The variety of order is ascertained, and generalized Walsh cyclic spectrum of the above multi-output plateaued functions are presented. In addition, the injective sets are constructed. So a series of new multi-output plateaued functions are constructed by above methods.
In this paper, the multi-output plateaued functions are constructed by methods of affine transformation, concatenation, injective sets and the state transform matrix of m-sequences. The variety of order is ascertained, and generalized Walsh cyclic spectrum of the above multi-output plateaued functions are presented. In addition, the injective sets are constructed. So a series of new multi-output plateaued functions are constructed by above methods.
2008, 30(12): 2996-2998.
doi: 10.3724/SP.J.1146.2007.00873
Abstract:
A broadcast encryption scheme based on the interpolating polynomial is proposed. It allows the sender to designate multi-receivers to the Authority Center (AC). The interpolating polynomial is constructed and the related information is proclaimed by AC. The interpolating polynomial can be reconstructed by computing the central point of line segment to achieve the purpose of broadcasting safely by the legal users using their secret information and the public information published by AC.
A broadcast encryption scheme based on the interpolating polynomial is proposed. It allows the sender to designate multi-receivers to the Authority Center (AC). The interpolating polynomial is constructed and the related information is proclaimed by AC. The interpolating polynomial can be reconstructed by computing the central point of line segment to achieve the purpose of broadcasting safely by the legal users using their secret information and the public information published by AC.
2008, 30(12): 2999-3004.
doi: 10.3724/SP.J.1146.2008.00220
Abstract:
This paper specifies a Proxy Mobile IPv6 based Global Mobility Management architecture and protocol procedure, named PMIPGMM. In PMIPGMM, the mobility management is performed by network entity other than mobile node itself. The other benefit is the elimination of the wireless link data delivery tunnel overhead between the mobile node and the access router. To compare with well known hierarchical mobile IPv6 mobility management protocol, the location update, the packet delivery and total cost functions generated by a mobile node during its average domain residence time in each protocol are formulated based on fluid flow mobility model. Then, the impacts of various system parameters on the cost functions are analyzed, respectively. The analysis results indicate that the proposed proxy mobile IPv6 based global mobility management protocol can guarantees lower total costs.
This paper specifies a Proxy Mobile IPv6 based Global Mobility Management architecture and protocol procedure, named PMIPGMM. In PMIPGMM, the mobility management is performed by network entity other than mobile node itself. The other benefit is the elimination of the wireless link data delivery tunnel overhead between the mobile node and the access router. To compare with well known hierarchical mobile IPv6 mobility management protocol, the location update, the packet delivery and total cost functions generated by a mobile node during its average domain residence time in each protocol are formulated based on fluid flow mobility model. Then, the impacts of various system parameters on the cost functions are analyzed, respectively. The analysis results indicate that the proposed proxy mobile IPv6 based global mobility management protocol can guarantees lower total costs.
2008, 30(12): 3005-3008.
doi: 10.3724/SP.J.1146.2007.00889
Abstract:
In this paper, with uncertain demands, a robust optimization strategy is proposed to optimally solve the splitter placement problem for multicast in all-optical networks. The test in the paper shows that using robust strategy, the resource provisioning of each scenario is closer to the optimal resource consumption, more robust, less resource consumption and more practically than the static solution.
In this paper, with uncertain demands, a robust optimization strategy is proposed to optimally solve the splitter placement problem for multicast in all-optical networks. The test in the paper shows that using robust strategy, the resource provisioning of each scenario is closer to the optimal resource consumption, more robust, less resource consumption and more practically than the static solution.
2008, 30(12): 3009-3012.
doi: 10.3724/SP.J.1146.2007.00869
Abstract:
Based on the broad band multiplex system which provides real time VBR services with a complete sharing policy and best effort service, this paper focuses its attention on the average residual capacity, packet loss probability of real time services and average delay of best effort service. Through comprehensive analysis of the multi-service queuing, this paper educes computation formulas of the main performance indexes and arrives at a new conclusion that the packet loss probability is not a monotonic function of the call level load. Simulation results prove that the formulas are correct.
Based on the broad band multiplex system which provides real time VBR services with a complete sharing policy and best effort service, this paper focuses its attention on the average residual capacity, packet loss probability of real time services and average delay of best effort service. Through comprehensive analysis of the multi-service queuing, this paper educes computation formulas of the main performance indexes and arrives at a new conclusion that the packet loss probability is not a monotonic function of the call level load. Simulation results prove that the formulas are correct.
2008, 30(12): 3013-3017.
doi: 10.3724/SP.J.1146.2007.00821
Abstract:
Efficient energy conservation plays an important role in the performance of wireless Ad hoc networks because the nodes in such networks are usually equipped with battery. In order to reduce energy consumption in the network, a TPR (Topology-based Power-aware Routing) protocol is proposed. By using the character that more hops can save more energy in wireless transmission, the TPR protocol builds power-efficient-topology in the one hop of nodes, and utilizes this topology to control the process of route discovery, then sets up energy-efficient route. Simulation results indicate that the TPR protocol can conserve more energy, and balance the performance of route overhead, route discovery time, end to end delay etc.
Efficient energy conservation plays an important role in the performance of wireless Ad hoc networks because the nodes in such networks are usually equipped with battery. In order to reduce energy consumption in the network, a TPR (Topology-based Power-aware Routing) protocol is proposed. By using the character that more hops can save more energy in wireless transmission, the TPR protocol builds power-efficient-topology in the one hop of nodes, and utilizes this topology to control the process of route discovery, then sets up energy-efficient route. Simulation results indicate that the TPR protocol can conserve more energy, and balance the performance of route overhead, route discovery time, end to end delay etc.
2008, 30(12): 3018-3022.
doi: 10.3724/SP.J.1146.2007.01993
Abstract:
Batching is a simple but efficient scheduling mechanism for streaming media. An optimization model for average access delay is formulated to obtain the key aspects affecting the performance of Batching. Based on the analytical results, the maximum urgency first batching policy and its heuristic implementations are proposed. The definition of urgency considers multiple attributes of the waiting queue. Whenever a channel becomes available, the proposed policy schedules the video with the largest urgency value. The effectiveness and feasibility of the presented schemes are evaluated and justified experimentally using simulation.
Batching is a simple but efficient scheduling mechanism for streaming media. An optimization model for average access delay is formulated to obtain the key aspects affecting the performance of Batching. Based on the analytical results, the maximum urgency first batching policy and its heuristic implementations are proposed. The definition of urgency considers multiple attributes of the waiting queue. Whenever a channel becomes available, the proposed policy schedules the video with the largest urgency value. The effectiveness and feasibility of the presented schemes are evaluated and justified experimentally using simulation.
2008, 30(12): 3023-3026.
doi: 10.3724/SP.J.1146.2008.00067
Abstract:
Most of the existing protocols construct P2P topologies based on the history of P2P nodes actions, however, they can not ensure the efficiency of the topologies in time, when facing the complexity and turbulence of P2P nodes strategies. This paper firstly builds the game model of the interactions and payoffs of various types of P2P nodes. In this foundation, this paper proposes the TATP based on the identification mechanism of P2P nodes types. The simulations show that the good nodes will begin to congregate and the bad ones will be excluded to the edge of the networks. The results also indicate that TATP will improve the efficiency and security of P2P topologies, with less network costs, even in the worst network environments.
Most of the existing protocols construct P2P topologies based on the history of P2P nodes actions, however, they can not ensure the efficiency of the topologies in time, when facing the complexity and turbulence of P2P nodes strategies. This paper firstly builds the game model of the interactions and payoffs of various types of P2P nodes. In this foundation, this paper proposes the TATP based on the identification mechanism of P2P nodes types. The simulations show that the good nodes will begin to congregate and the bad ones will be excluded to the edge of the networks. The results also indicate that TATP will improve the efficiency and security of P2P topologies, with less network costs, even in the worst network environments.
2008, 30(12): 3027-3030.
doi: 10.3724/SP.J.1146.2007.00922
Abstract:
An enhanced DCF scheme, called U-DCF, based on logarithm utility function is proposed in this paper, since bandwidth resource can not be utilized efficiently in the chosen backoff parameters of 802.11 DCF. The users utility is a function of his data throughput, thus the bandwidth resource utilization problem is modeled as a utility based constrained maximization problem, called a system problem. A user problem formulation of the system problem is derived by using Lagrange relaxation and duality theory, thus the competing stations only need to choose their optimal channel access strategies (CWmin) independently to maximize their net utility. Then the maximum aggregate utilities can be achieved in a distributed way. Simulation results show that, by adjusting the backoff parameter CWmin to the average frame-length and the number of the competing stations on the channel, U-DCF outperforms the original DCF in terms of system throughputs, delay bound and frame-loss-rate.
An enhanced DCF scheme, called U-DCF, based on logarithm utility function is proposed in this paper, since bandwidth resource can not be utilized efficiently in the chosen backoff parameters of 802.11 DCF. The users utility is a function of his data throughput, thus the bandwidth resource utilization problem is modeled as a utility based constrained maximization problem, called a system problem. A user problem formulation of the system problem is derived by using Lagrange relaxation and duality theory, thus the competing stations only need to choose their optimal channel access strategies (CWmin) independently to maximize their net utility. Then the maximum aggregate utilities can be achieved in a distributed way. Simulation results show that, by adjusting the backoff parameter CWmin to the average frame-length and the number of the competing stations on the channel, U-DCF outperforms the original DCF in terms of system throughputs, delay bound and frame-loss-rate.
2008, 30(12): 3031-3034.
doi: 10.3724/SP.J.1146.2007.00586
Abstract:
Based on the linear stability theory, a new simple nonlinear feedback control method is proposed. The technique can be applied to drive the generalized projective synchronization for two new same hyper-chaotic systems or two different hyper-chaotic systems. This property can arbitrarily direct the scaling factor into a desired value. Numerical simulations show the effectiveness of the controller.
Based on the linear stability theory, a new simple nonlinear feedback control method is proposed. The technique can be applied to drive the generalized projective synchronization for two new same hyper-chaotic systems or two different hyper-chaotic systems. This property can arbitrarily direct the scaling factor into a desired value. Numerical simulations show the effectiveness of the controller.
