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2012 Vol. 34, No. 5
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2012, 34(5): 1017-1023.
doi: 10.3724/SP.J.1146.2011.01003
Abstract:
Downward-looking 3-D Synthetic Aperture Radar (SAR) can be used for three-dimensional reconstruction of the targets in the inferior of the platform of the SAR, and it has wide application prospects. An imaging method of downward-looking 3-D SAR is proposed, which is in the case of the thinned arrays, and this method reduces effectively the antenna elements. In order to suppress the sidelobe brought by thinned arrays, the Compressed Sensing (CS) theory is used in the proposed method. This paper also analysis how distribution of the sparse arrays influences the sparse signal processing and the feasibility of using the compressed sensing theory in 3-D SAR imaging. The simulation results validate the correctness of the analysis and the effectiveness of the proposed algorithm.
Downward-looking 3-D Synthetic Aperture Radar (SAR) can be used for three-dimensional reconstruction of the targets in the inferior of the platform of the SAR, and it has wide application prospects. An imaging method of downward-looking 3-D SAR is proposed, which is in the case of the thinned arrays, and this method reduces effectively the antenna elements. In order to suppress the sidelobe brought by thinned arrays, the Compressed Sensing (CS) theory is used in the proposed method. This paper also analysis how distribution of the sparse arrays influences the sparse signal processing and the feasibility of using the compressed sensing theory in 3-D SAR imaging. The simulation results validate the correctness of the analysis and the effectiveness of the proposed algorithm.
2012, 34(5): 1024-1029.
doi: 10.3724/SP.J.1146.2011.01195
Abstract:
The conventional Ground Penetrating Radar (GPR) imaging algorithms are data-independent, which cause lots of interference like side lobes and clutter. However, the data-adaptive methods have remarkable capability of interference suppression. A data-adaptive GPR imaging algorithm based on the theory of Robust Capon Beamforming (RCB) is proposed. The refraction phenomenon of electromagnetic wave is fully considered, and the generation of covariance matrix is also deeply discussed. The sidelobes and clutter can be suppressed dramatically, as well as the imaging resolution can be slightly improved. The experimental results show the validity of the proposed algorithm.
The conventional Ground Penetrating Radar (GPR) imaging algorithms are data-independent, which cause lots of interference like side lobes and clutter. However, the data-adaptive methods have remarkable capability of interference suppression. A data-adaptive GPR imaging algorithm based on the theory of Robust Capon Beamforming (RCB) is proposed. The refraction phenomenon of electromagnetic wave is fully considered, and the generation of covariance matrix is also deeply discussed. The sidelobes and clutter can be suppressed dramatically, as well as the imaging resolution can be slightly improved. The experimental results show the validity of the proposed algorithm.
2012, 34(5): 1030-1037.
doi: 10.3724/SP.J.1146.2011.00920
Abstract:
An approach based on the square successive difference of neighborhood averages is proposed to extract edges in SAR images. The proposed operator partitions the neighborhood window of a pixel into many non-overlapping regions, and applies the mean square successive difference as an indicator of the edge strength. It is proved regardless of the mean intensity and is an edge detector with Constant False Alarms Rate (CFAR) theoretically. It also performs well in the estimation of edge orientations. The edge thinning algorithm and an adaptive double-thresholds processing are carried out to reduce false alarms nearby the true edges and to connect edges. The experiments on simulated and real SAR images indicate that the proposed operator achieves well performance in the edge detection and localization, and the extracted edge segments are long and continuous.
An approach based on the square successive difference of neighborhood averages is proposed to extract edges in SAR images. The proposed operator partitions the neighborhood window of a pixel into many non-overlapping regions, and applies the mean square successive difference as an indicator of the edge strength. It is proved regardless of the mean intensity and is an edge detector with Constant False Alarms Rate (CFAR) theoretically. It also performs well in the estimation of edge orientations. The edge thinning algorithm and an adaptive double-thresholds processing are carried out to reduce false alarms nearby the true edges and to connect edges. The experiments on simulated and real SAR images indicate that the proposed operator achieves well performance in the edge detection and localization, and the extracted edge segments are long and continuous.
2012, 34(5): 1038-1044.
doi: 10.3724/SP.J.1146.2011.00938
Abstract:
A novel mixed iteration filtering algorithm is presented to reduce speckle noise in SAR image by combining the Lee filter with variable-size windows and self-snake diffusion, and an effect method to estimate noises variance of SAR image is given. Local statistical parameters of SAR image is first estimated, and then SAR image is smoothed by improved Lee filter with variable-size windows. Then self-snake diffusion is used to remove the remaining isolated points noise and edge noise in the image smoothed by Lee filter. The window size of Lee filter will be increased with the number of mixed iteration, and thus homogeneous regions of SAR image are smoothed better while image edge is protected. The experimental results show that, compared with several kinds of despeckling algorithms, the proposed algorithm has better performance in speckle suppression and edge protection.
A novel mixed iteration filtering algorithm is presented to reduce speckle noise in SAR image by combining the Lee filter with variable-size windows and self-snake diffusion, and an effect method to estimate noises variance of SAR image is given. Local statistical parameters of SAR image is first estimated, and then SAR image is smoothed by improved Lee filter with variable-size windows. Then self-snake diffusion is used to remove the remaining isolated points noise and edge noise in the image smoothed by Lee filter. The window size of Lee filter will be increased with the number of mixed iteration, and thus homogeneous regions of SAR image are smoothed better while image edge is protected. The experimental results show that, compared with several kinds of despeckling algorithms, the proposed algorithm has better performance in speckle suppression and edge protection.
2012, 34(5): 1045-1050.
doi: 10.3724/SP.J.1146.2011.01120
Abstract:
In Ground Penetrating Radar (GPR) applications such as detection of targets located in layered medium, the time-domain Back Projection (BP) imaging algorithm is a commonly used imaging technique. However, the heavy computation burden and low-quality imaging results limit the practical application of this algorithm. This paper presents a new Fast Back Projection (FBP) high-resolution imaging method. Firstly, a new fast time-delay calculation method based on one-dimensional search operation or a quadratic equation solving operation is presented. Secondly, a new method to improve the quality of imaging results by using weighted factor is presented and a typical weighted factor is designed. Through processing simulation data, the FBP imaging results show that the algorithm can be applied effectively to the target imaging embedded in two layered medium.
In Ground Penetrating Radar (GPR) applications such as detection of targets located in layered medium, the time-domain Back Projection (BP) imaging algorithm is a commonly used imaging technique. However, the heavy computation burden and low-quality imaging results limit the practical application of this algorithm. This paper presents a new Fast Back Projection (FBP) high-resolution imaging method. Firstly, a new fast time-delay calculation method based on one-dimensional search operation or a quadratic equation solving operation is presented. Secondly, a new method to improve the quality of imaging results by using weighted factor is presented and a typical weighted factor is designed. Through processing simulation data, the FBP imaging results show that the algorithm can be applied effectively to the target imaging embedded in two layered medium.
2012, 34(5): 1051-1056.
doi: 10.3724/SP.J.1146.2011.00986
Abstract:
This paper estimates high-resolution radial velocity and range profile of moving target for Ultra- WideBand (UWB) radar via State-Space (SS) method. First, an impulse response of scatterers in frequency domain is obtained by utilizing the echo with stretching in UWB radar to get the Hankel matrix used in SS method. Second, through SS, the radial velocity and range profile of target moving at high speed are estimated for UWB radar. The corresponding Cramr-Rao Lower Bound (CRLB) is further derived. This method is not only can estimate the high resolution range profile of the target, but also can avoid the variation of Doppler with the frequency in the bandwidth of signal, i.e., the influence of Doppler dispersion on radial velocity estimates. Also, this method has fine noise-rejection ability. Besides, due to only acquiring the impulse response in frequency domain and no considering the special waveform, the method there is not the restriction of the transmitted waveform, which is greatly different with wavelet transform. The simulation results corroborate the feasibility and effectivity of this method.
This paper estimates high-resolution radial velocity and range profile of moving target for Ultra- WideBand (UWB) radar via State-Space (SS) method. First, an impulse response of scatterers in frequency domain is obtained by utilizing the echo with stretching in UWB radar to get the Hankel matrix used in SS method. Second, through SS, the radial velocity and range profile of target moving at high speed are estimated for UWB radar. The corresponding Cramr-Rao Lower Bound (CRLB) is further derived. This method is not only can estimate the high resolution range profile of the target, but also can avoid the variation of Doppler with the frequency in the bandwidth of signal, i.e., the influence of Doppler dispersion on radial velocity estimates. Also, this method has fine noise-rejection ability. Besides, due to only acquiring the impulse response in frequency domain and no considering the special waveform, the method there is not the restriction of the transmitted waveform, which is greatly different with wavelet transform. The simulation results corroborate the feasibility and effectivity of this method.
2012, 34(5): 1057-1064.
doi: 10.3724/SP.J.1146.2011.00991
Abstract:
The moving target detection based on multiple azimuth resolution images is proposed for Ground Moving Target Indication (GMTI) in the low frequency Synthetic Aperture Radar (SAR). This paper analyzes the characteristics of static and moving target on a seriers of images with different azimuth resolutions first. The azimuth 3 dB Impulsion Response Width (IRW), range smearing distance and the unitary energy are used to distinguish moving target from static targets. Then, the moving target detection algorithm is presented based on these characteristics. This algorithm has lower computation load and lower Signal-to-Noise Ratio (SNR) and can detect the moving target quickly. The range of velocity detection is wide, which is suitable for practice. Both simulation and real data experiment illustrate the effectiveness of this algorithm.
The moving target detection based on multiple azimuth resolution images is proposed for Ground Moving Target Indication (GMTI) in the low frequency Synthetic Aperture Radar (SAR). This paper analyzes the characteristics of static and moving target on a seriers of images with different azimuth resolutions first. The azimuth 3 dB Impulsion Response Width (IRW), range smearing distance and the unitary energy are used to distinguish moving target from static targets. Then, the moving target detection algorithm is presented based on these characteristics. This algorithm has lower computation load and lower Signal-to-Noise Ratio (SNR) and can detect the moving target quickly. The range of velocity detection is wide, which is suitable for practice. Both simulation and real data experiment illustrate the effectiveness of this algorithm.
2012, 34(5): 1065-1069.
doi: 10.3724/SP.J.1146.2011.01010
Abstract:
A high frequency surface wave radar antenna array calibration method using Automatic Identification System (AIS) data is presented. The new method uses ship target echoes with high SNR and their AIS data to find the phase and gain errors of the antenna array. The new method can achieve better array calibration precision comparing to existing blind array calibration methods, requires no dedicate beacons, and can do the calibration at any time. Real measured high frequency surface wave radar data and corresponding AIS data are used to test the new method, and the result proves the advantage of the new method.
A high frequency surface wave radar antenna array calibration method using Automatic Identification System (AIS) data is presented. The new method uses ship target echoes with high SNR and their AIS data to find the phase and gain errors of the antenna array. The new method can achieve better array calibration precision comparing to existing blind array calibration methods, requires no dedicate beacons, and can do the calibration at any time. Real measured high frequency surface wave radar data and corresponding AIS data are used to test the new method, and the result proves the advantage of the new method.
2012, 34(5): 1070-1075.
doi: 10.3724/SP.J.1146.2011.00944
Abstract:
Stepped chirp radars achieve high range resolution through bandwidth synthesis. Precise beginning sampling range is a significant factor which guarantees the performance of bandwidth synthesis. The effect of the beginning sampling range error on bandwidth synthesis is discussed by the way of impulse response of linear system. The beginning sampling range error introduces step phase errors which remain in the synthesized broad band pulses and result in grating lobes in the compression results. The effects on the envelope, height and distribution of the grating lobes and the shift of the main lobe are analyzed quantitatively.
Stepped chirp radars achieve high range resolution through bandwidth synthesis. Precise beginning sampling range is a significant factor which guarantees the performance of bandwidth synthesis. The effect of the beginning sampling range error on bandwidth synthesis is discussed by the way of impulse response of linear system. The beginning sampling range error introduces step phase errors which remain in the synthesized broad band pulses and result in grating lobes in the compression results. The effects on the envelope, height and distribution of the grating lobes and the shift of the main lobe are analyzed quantitatively.
2012, 34(5): 1076-1081.
doi: 10.3724/SP.J.1146.2011.00921
Abstract:
SAR image despeckling is always a key and indispensable step in SAR image preprocessing. The Bilateral Filtering (BF), which combines grey similarity and spatial closeness to reduce noise, is introduced to SAR image despeckling recently. However, when BF is directly used for SAR image despeckling, it is hard to select the optimal spatial closeness variance and imprecise to measure the grey similarity by Gaussian function, so an Adaptive Bilateral Filter (ABF) is proposed. The ABF adjusts spatial closeness variance to the local coefficient of variation and calculates the grey similarity of SAR image by the likelihood probability function instead of the Gaussian function. The tests on synthesized and real SAR images show that the ABF can notably smooth speckles with imperceptible details pollution, which achieves better performance than that of the other related methods.
SAR image despeckling is always a key and indispensable step in SAR image preprocessing. The Bilateral Filtering (BF), which combines grey similarity and spatial closeness to reduce noise, is introduced to SAR image despeckling recently. However, when BF is directly used for SAR image despeckling, it is hard to select the optimal spatial closeness variance and imprecise to measure the grey similarity by Gaussian function, so an Adaptive Bilateral Filter (ABF) is proposed. The ABF adjusts spatial closeness variance to the local coefficient of variation and calculates the grey similarity of SAR image by the likelihood probability function instead of the Gaussian function. The tests on synthesized and real SAR images show that the ABF can notably smooth speckles with imperceptible details pollution, which achieves better performance than that of the other related methods.
Coherent Multi-target Localization for Bistatic MIMO Radar Based on Block Hankel Matrix Construction
2012, 34(5): 1082-1087.
doi: 10.3724/SP.J.1146.2011.00896
Abstract:
A new algorithm for angle estimation in the presence of coherent multi-target is presented. A block Hankel matrix is constructed by utilizing the elements of the receive covariance matrix. It is shown that the rank of the block Hankel matrix is equal to the number of targets, and is independent of the coherency of targets. The signal subspace is obtained by using the Singular Value Decomposition (SVD) of the block Hankel matrix. Thus the ESPRIT algorithm can directly be applied to estimate the Direction Of Departure (DOD) and the Direction Of Arrival (DOA). The simulation results illustrate that: the DOD and DOA of the coherent target can be estimated efficiently with automatic pairing. And comparing to the two-dimensional spatial smoothing algorithm, the proposed method provides better estimation performance, especially in the condition of low Signal to Noise Ratio (SNR) and low snapshot numbers.
A new algorithm for angle estimation in the presence of coherent multi-target is presented. A block Hankel matrix is constructed by utilizing the elements of the receive covariance matrix. It is shown that the rank of the block Hankel matrix is equal to the number of targets, and is independent of the coherency of targets. The signal subspace is obtained by using the Singular Value Decomposition (SVD) of the block Hankel matrix. Thus the ESPRIT algorithm can directly be applied to estimate the Direction Of Departure (DOD) and the Direction Of Arrival (DOA). The simulation results illustrate that: the DOD and DOA of the coherent target can be estimated efficiently with automatic pairing. And comparing to the two-dimensional spatial smoothing algorithm, the proposed method provides better estimation performance, especially in the condition of low Signal to Noise Ratio (SNR) and low snapshot numbers.
2012, 34(5): 1088-1095.
doi: 10.3724/SP.J.1146.2011.00973
Abstract:
Sparse Frequency Waveform (SFW) can be transmitted by radar systems to overcome narrowband interferences. However, SFW suffers the raised range sidelobes generally, leading to worsening detection performance for weak targets. To solve this problem, a method to design a phase-coded SFW with low range sidelobes is proposed in this paper. The objective function is constructed according to jointly minimizing the mean square error of the power spectrum density with range sidelobes. The Cycle Iterative Algorithm (CIA) based on Fast Fourier Transform (FFT) is put forward to search for the optimal phase-coded waveform. The proposed method is then extended for Multiple-Input Multiple-Output (MIMO) radar to design a set of phase codes of SFW with good auto-/cross-correlation performances. The presented method searches along the direction making sure the objective function nonincreasing and need not compute conjugate gradient. It has a low computation complexity and can be used to design and update the transmit waveform rapidly. Simulation results demonstrate the effectiveness and flexibility of the proposed method.
Sparse Frequency Waveform (SFW) can be transmitted by radar systems to overcome narrowband interferences. However, SFW suffers the raised range sidelobes generally, leading to worsening detection performance for weak targets. To solve this problem, a method to design a phase-coded SFW with low range sidelobes is proposed in this paper. The objective function is constructed according to jointly minimizing the mean square error of the power spectrum density with range sidelobes. The Cycle Iterative Algorithm (CIA) based on Fast Fourier Transform (FFT) is put forward to search for the optimal phase-coded waveform. The proposed method is then extended for Multiple-Input Multiple-Output (MIMO) radar to design a set of phase codes of SFW with good auto-/cross-correlation performances. The presented method searches along the direction making sure the objective function nonincreasing and need not compute conjugate gradient. It has a low computation complexity and can be used to design and update the transmit waveform rapidly. Simulation results demonstrate the effectiveness and flexibility of the proposed method.
2012, 34(5): 1096-1101.
doi: 10.3724/SP.J.1146.2011.00978
Abstract:
For low frequency spaceborne Synthetic Aperture Radar (SAR) systems, the ionosphere will have a significant effect on SAR calibration. In this paper, an approach for ionospheric effects correction on spaceborne SAR calibration based on Active Radar Calibrator (ARC) is proposed. The range-displacement induced by ionosphere group delay and the degradation of the range resolution resulted from ionosphere dispersion effect are analyzed, and the effects are corrected by using the width change of the transmitted pulse measured by internal calibration and ARC. The imaging results of ARC before and after correction from simulation are presented. The results show that image quality in range is improved greatly after correction and the approach is proved to be valid.
For low frequency spaceborne Synthetic Aperture Radar (SAR) systems, the ionosphere will have a significant effect on SAR calibration. In this paper, an approach for ionospheric effects correction on spaceborne SAR calibration based on Active Radar Calibrator (ARC) is proposed. The range-displacement induced by ionosphere group delay and the degradation of the range resolution resulted from ionosphere dispersion effect are analyzed, and the effects are corrected by using the width change of the transmitted pulse measured by internal calibration and ARC. The imaging results of ARC before and after correction from simulation are presented. The results show that image quality in range is improved greatly after correction and the approach is proved to be valid.
2012, 34(5): 1102-1108.
doi: 10.3724/SP.J.1146.2011.00992
Abstract:
Airborne MIMO radar uses its temporal freedom and receiving transmitting spatial freedom to suppress clutter, while it nulls jammers by only receiving spatial freedom. Based on these characteristic, a novel two-stage method is presented in this paper, which separates suppression of clutter and jammers into two sequential stages. First, jammers are nulled with partial receiving freedom, and dimension reduction is also implemented. Second, matched-filtering is applied to the output data after jammer suppression, followed by clutter suppression using temporal and spatial freedom. Through the two-stage processing, transmitting spatial freedom can be fully utilized in clutter suppression together with reducing the computational load and sample requirement effectively. Both theoretic analysis and simulation experiments present that，in the presence of strong jammers, performance of the proposal can approach to that of the full dimension space-time adaptive processing for MIMO radar.
Airborne MIMO radar uses its temporal freedom and receiving transmitting spatial freedom to suppress clutter, while it nulls jammers by only receiving spatial freedom. Based on these characteristic, a novel two-stage method is presented in this paper, which separates suppression of clutter and jammers into two sequential stages. First, jammers are nulled with partial receiving freedom, and dimension reduction is also implemented. Second, matched-filtering is applied to the output data after jammer suppression, followed by clutter suppression using temporal and spatial freedom. Through the two-stage processing, transmitting spatial freedom can be fully utilized in clutter suppression together with reducing the computational load and sample requirement effectively. Both theoretic analysis and simulation experiments present that，in the presence of strong jammers, performance of the proposal can approach to that of the full dimension space-time adaptive processing for MIMO radar.
2012, 34(5): 1109-1114.
doi: 10.3724/SP.J.1146.2011.01062
Abstract:
It is extremely difficult to extract road from high-resolution SAR images because of the existence of various kinds of disturbances, occlusions and shadowing. A new road center-point extraction method is proposed by combined using local detection and global tracking. In local detection phase, two windows are set. The outside window is used to obtain the local road direction by using non-linear structure tensor, based on the fact that fences, green belts and other disturbances point to a consistent direction with the edge of roads. The inside window adjusts its direction by the result of non-linear structure tensor. Then it searches for the road areas, and determines the width and center of roads. In global tracking phase, particle filter of variable-step is used for solving the problem of tracking broken frequently by occlusions on the road and shadowing alongside the road. In 1 m high-resolution airborne SAR image experiment, the results indicate that this method is effective.
It is extremely difficult to extract road from high-resolution SAR images because of the existence of various kinds of disturbances, occlusions and shadowing. A new road center-point extraction method is proposed by combined using local detection and global tracking. In local detection phase, two windows are set. The outside window is used to obtain the local road direction by using non-linear structure tensor, based on the fact that fences, green belts and other disturbances point to a consistent direction with the edge of roads. The inside window adjusts its direction by the result of non-linear structure tensor. Then it searches for the road areas, and determines the width and center of roads. In global tracking phase, particle filter of variable-step is used for solving the problem of tracking broken frequently by occlusions on the road and shadowing alongside the road. In 1 m high-resolution airborne SAR image experiment, the results indicate that this method is effective.
2012, 34(5): 1115-1119.
doi: 10.3724/SP.J.1146.2011.00883
Abstract:
Considering the issue that full-dimensional adaptive beam-forming takes usually a large number of sampling data and has very high computation cost by using Sample Matrix Inverse (SMI) algorithm, a new adaptive Beam-Forming algorithm based on Subspace ReConstructing (SRC-BF) is proposed in this paper. Illuminated by the multi-dimensional array data having the characteristics of reconstruction of fractal-dimension, the proposed approach is carried out in three stages. Firstly, the fractal-dimensional signal subspace of the array data is estimated using training samples; Secondly, the full-dimensional signal subspace is reconstructed by adopting the tensor product operation and the cross terms is removed adaptively; Finally, the beam-forming weight vector is deduced by the subspace projection algorithm. Theoretical analysis and simulation results show that the method has lower computational complexity and can effectively improve the output Signal-to- Interference-plus-Noise Ration (SINR) with the small sample support.
Considering the issue that full-dimensional adaptive beam-forming takes usually a large number of sampling data and has very high computation cost by using Sample Matrix Inverse (SMI) algorithm, a new adaptive Beam-Forming algorithm based on Subspace ReConstructing (SRC-BF) is proposed in this paper. Illuminated by the multi-dimensional array data having the characteristics of reconstruction of fractal-dimension, the proposed approach is carried out in three stages. Firstly, the fractal-dimensional signal subspace of the array data is estimated using training samples; Secondly, the full-dimensional signal subspace is reconstructed by adopting the tensor product operation and the cross terms is removed adaptively; Finally, the beam-forming weight vector is deduced by the subspace projection algorithm. Theoretical analysis and simulation results show that the method has lower computational complexity and can effectively improve the output Signal-to- Interference-plus-Noise Ration (SINR) with the small sample support.
2012, 34(5): 1120-1125.
doi: 10.3724/SP.J.1146.2011.01036
Abstract:
To overcome effectively the influence of large steering vector mismatch on the performance of adaptive beamformer, an Iterative diagonally Loaded Sample Matrix Inverse (ILSMI) robust adaptive beamformer is proposed in this paper. The iterative computation of conventional diagonally Loaded Sample Matrix Inverse (LSMI) method is implemented in the proposed approach. Based on the relationship between the optimal weight vector and the assumed steering vector of the Capon beamformer, the more precise corresponding steering vector of the LSMI optimal weight vector is estimated in each iteration and used to replace the assumed steering vector, and the converged estimation will approach to the real steering vector. The proposed approach can obviously improve the output Signal-to-Interference-and-Noise Ratio (SINR) of the robust beamformer through only one key recursive formula, without any Lagrange multiplier methodology or convex optimization methods in each iteration. The simulation results verify the correctness and validity of the proposed approach.
To overcome effectively the influence of large steering vector mismatch on the performance of adaptive beamformer, an Iterative diagonally Loaded Sample Matrix Inverse (ILSMI) robust adaptive beamformer is proposed in this paper. The iterative computation of conventional diagonally Loaded Sample Matrix Inverse (LSMI) method is implemented in the proposed approach. Based on the relationship between the optimal weight vector and the assumed steering vector of the Capon beamformer, the more precise corresponding steering vector of the LSMI optimal weight vector is estimated in each iteration and used to replace the assumed steering vector, and the converged estimation will approach to the real steering vector. The proposed approach can obviously improve the output Signal-to-Interference-and-Noise Ratio (SINR) of the robust beamformer through only one key recursive formula, without any Lagrange multiplier methodology or convex optimization methods in each iteration. The simulation results verify the correctness and validity of the proposed approach.
2012, 34(5): 1126-1130.
doi: 10.3724/SP.J.1146.2011.01051
Abstract:
Transmit beampattern for MIMO array with collocated antennas is usually obtained by optimization of signal correlation matrix. These methods have disadvantages of the performance strongly depending on initialization parameters and computation complexity. This paper presents a set of basic beams created by minimizing sidelobe level beamforming of uniform linear array using second-order cone programs method, based on the idea that an arbitrary beampattern can be synthesized by a set of basic beam. Then the weighted coefficients of basic beam of transmit beampattern can fastly be computed. The presented method possesses more minimized sidelobe and smoother mainlobe. The efficiency and validity are verified by the simulation results.
Transmit beampattern for MIMO array with collocated antennas is usually obtained by optimization of signal correlation matrix. These methods have disadvantages of the performance strongly depending on initialization parameters and computation complexity. This paper presents a set of basic beams created by minimizing sidelobe level beamforming of uniform linear array using second-order cone programs method, based on the idea that an arbitrary beampattern can be synthesized by a set of basic beam. Then the weighted coefficients of basic beam of transmit beampattern can fastly be computed. The presented method possesses more minimized sidelobe and smoother mainlobe. The efficiency and validity are verified by the simulation results.
2012, 34(5): 1131-1136.
doi: 10.3724/SP.J.1146.2011.00925
Abstract:
In order to achieve efficient coordination multiple point downlink transmission, a single iteration of distributed collaborative beamforming algorithm is proposed based on the merit of maximizing the minimum SINR, and the global convergence of the proposed algorithm is proven. Furthermore, a distributed coordinated user scheduling algorithm is developed by using characteristics of optimum beam in the proposed algorithm. Simulation results show that the proposed distributed coordinated beamforming and user scheduling algorithm is superior to existing algorithms in term of the minimum user SINR performance, and only a small amount of information exchange between base stations.
In order to achieve efficient coordination multiple point downlink transmission, a single iteration of distributed collaborative beamforming algorithm is proposed based on the merit of maximizing the minimum SINR, and the global convergence of the proposed algorithm is proven. Furthermore, a distributed coordinated user scheduling algorithm is developed by using characteristics of optimum beam in the proposed algorithm. Simulation results show that the proposed distributed coordinated beamforming and user scheduling algorithm is superior to existing algorithms in term of the minimum user SINR performance, and only a small amount of information exchange between base stations.
2012, 34(5): 1137-1141.
doi: 10.3724/SP.J.1146.2011.01077
Abstract:
For target tracking by using single feature results in a poor performance in robustness, an infrared object tracking method based on adaptive multi-features fusion and Mean Shift (MS) is presented. In order to enhance the important features, the proposed method advances local contrast mean difference characteristic and uses advanced local contrast mean difference characteristic and grey features to present the interested target. Uncertainty measurement method is introduced in features fusion to adjust the relative contributions of different features adaptively, and the robustness of MS algorithm is significantly enhanced. Furthermore, scale operator is introduced to update tracking window in order to improve the tracking performance in size-changing target. Experimental results indicate the proposed method is more robust to present object and has good performance in complex scene.
For target tracking by using single feature results in a poor performance in robustness, an infrared object tracking method based on adaptive multi-features fusion and Mean Shift (MS) is presented. In order to enhance the important features, the proposed method advances local contrast mean difference characteristic and uses advanced local contrast mean difference characteristic and grey features to present the interested target. Uncertainty measurement method is introduced in features fusion to adjust the relative contributions of different features adaptively, and the robustness of MS algorithm is significantly enhanced. Furthermore, scale operator is introduced to update tracking window in order to improve the tracking performance in size-changing target. Experimental results indicate the proposed method is more robust to present object and has good performance in complex scene.
2012, 34(5): 1142-1147.
doi: 10.3724/SP.J.1146.2011.01011
Abstract:
In this paper, an improved TV-Stokes image inpainting model is proposed based on the study of image inpainting. By analysing the properties of new model, an efficient and fast numerical algorithm is introduced. There are two variables in the new model, so it is firstly turned into two simple submodels by using alternating iteration method in the new algorithm, and then the two subproblems are solved using dual formulation and split Bregman method respectively. Experimental results show the new algorithm can not only get the better inpainting effect, but also improve the inpainting speed.
In this paper, an improved TV-Stokes image inpainting model is proposed based on the study of image inpainting. By analysing the properties of new model, an efficient and fast numerical algorithm is introduced. There are two variables in the new model, so it is firstly turned into two simple submodels by using alternating iteration method in the new algorithm, and then the two subproblems are solved using dual formulation and split Bregman method respectively. Experimental results show the new algorithm can not only get the better inpainting effect, but also improve the inpainting speed.
2012, 34(5): 1148-1153.
doi: 10.3724/SP.J.1146.2011.01012
Abstract:
Gait recognition research gets rapid development as one of biometric. Now almost all the gait recognition researcher focus on gait recognition rate only in the single condition, but the gait recognition rate has rapid decline in the wearing coat and carrying bag condition. Based on analyzing the gait timing characteristics when human is moving, a novel gait recognition model that expressed two-scale dynamic Bayesian network and more information fusion is proposed. The model contains four levels of states and every time slice of the model is expressed by the fusion of large-scale information and small-scale information. This model can well express the timing characteristics of gait, that are the body posture and range of motion and other gait rhythmic changes characteristics. Experimental result show that the model recognizes gait with high rates and good robustness to the silhouette noise and lost of information and fuse the large-scale information and small-scale information well. The model can greatly reduce impact of gait recognition rate in the wearing coat and carrying bag condition.
Gait recognition research gets rapid development as one of biometric. Now almost all the gait recognition researcher focus on gait recognition rate only in the single condition, but the gait recognition rate has rapid decline in the wearing coat and carrying bag condition. Based on analyzing the gait timing characteristics when human is moving, a novel gait recognition model that expressed two-scale dynamic Bayesian network and more information fusion is proposed. The model contains four levels of states and every time slice of the model is expressed by the fusion of large-scale information and small-scale information. This model can well express the timing characteristics of gait, that are the body posture and range of motion and other gait rhythmic changes characteristics. Experimental result show that the model recognizes gait with high rates and good robustness to the silhouette noise and lost of information and fuse the large-scale information and small-scale information well. The model can greatly reduce impact of gait recognition rate in the wearing coat and carrying bag condition.
2012, 34(5): 1154-1161.
doi: 10.3724/SP.J.1146.2011.00887
Abstract:
In object retrieval area, the current mainstream solution is Bag of Visual Words (BoVW) method, but there are several problems existing in the conventional BoVW methods, such as low time efficiency and large memory consumption, the synonymy and ambiguity of visual words. In this paper, a method based on randomized visual dictionaries and query expansion is proposed considering the above problems. Firstly, Exact Euclidean Locality Sensitive Hashing (E2LSH) is used to cluster local features of the training dataset, and a group of scalable randomized visual vocabularies is constructed. Then, the visual words distribution histograms and index files are created according to these randomized vocabularies. Finally, a query expansion strategy is introduced to accomplish object retrieval. Experimental results indicate that the distinguishability of objects is effectively improved and the object retrieval accuracy of the novel method is boosted dramatically compared with the classical methods, besides, it adapts large scale datasets well.
In object retrieval area, the current mainstream solution is Bag of Visual Words (BoVW) method, but there are several problems existing in the conventional BoVW methods, such as low time efficiency and large memory consumption, the synonymy and ambiguity of visual words. In this paper, a method based on randomized visual dictionaries and query expansion is proposed considering the above problems. Firstly, Exact Euclidean Locality Sensitive Hashing (E2LSH) is used to cluster local features of the training dataset, and a group of scalable randomized visual vocabularies is constructed. Then, the visual words distribution histograms and index files are created according to these randomized vocabularies. Finally, a query expansion strategy is introduced to accomplish object retrieval. Experimental results indicate that the distinguishability of objects is effectively improved and the object retrieval accuracy of the novel method is boosted dramatically compared with the classical methods, besides, it adapts large scale datasets well.
2012, 34(5): 1162-1167.
doi: 10.3724/SP.J.1146.2011.01014
Abstract:
To address the issue of line pattern mining of non-linear dataset, a new regression algorithm based on density weight Expectation Maximization (EM) and splitting merging strategy is proposed. Point-direction function is first employed to establish the expression of line pattern based on finite mixture model, and grid density is introduced into EM processing as adjust weight, which can effectively reduce the possibility of fall into local optimum of regression. Then a splitting merging strategy is introduced, which ensure the proposed algorithm can overcome the connectivity limitation, and can obtain a correct result even when the number of mining is not set as the same with the real line pattern number. Experiments demonstrate that the proposed algorithm is not sensitive to the set of mining number, and is able to correctly explore the line pattern of non-linear dataset under the noise environment.
To address the issue of line pattern mining of non-linear dataset, a new regression algorithm based on density weight Expectation Maximization (EM) and splitting merging strategy is proposed. Point-direction function is first employed to establish the expression of line pattern based on finite mixture model, and grid density is introduced into EM processing as adjust weight, which can effectively reduce the possibility of fall into local optimum of regression. Then a splitting merging strategy is introduced, which ensure the proposed algorithm can overcome the connectivity limitation, and can obtain a correct result even when the number of mining is not set as the same with the real line pattern number. Experiments demonstrate that the proposed algorithm is not sensitive to the set of mining number, and is able to correctly explore the line pattern of non-linear dataset under the noise environment.
2012, 34(5): 1168-1173.
doi: 10.3724/SP.J.1146.2011.00718
Abstract:
The modernization GPS system employes new Binary Offset Carrier (BOC) modulations, which achieve high performance in anti-jamming and code tracking. BOC modulations can be write as a sum of two coding signals. This can be generalized as multiple Spread Spectrum Direct Sequence (SS-DS) modulations transmitted by single radiator. This paper suggest that multiple spread spectrum signals should be processed as a new single signal for achieving high performance in anti-jamming and code tracking. Expression for error of code tracking is given in terms of signal parameters. Values of signal parameters for 3 dB outperform in code tracking are given finally.
The modernization GPS system employes new Binary Offset Carrier (BOC) modulations, which achieve high performance in anti-jamming and code tracking. BOC modulations can be write as a sum of two coding signals. This can be generalized as multiple Spread Spectrum Direct Sequence (SS-DS) modulations transmitted by single radiator. This paper suggest that multiple spread spectrum signals should be processed as a new single signal for achieving high performance in anti-jamming and code tracking. Expression for error of code tracking is given in terms of signal parameters. Values of signal parameters for 3 dB outperform in code tracking are given finally.
2012, 34(5): 1174-1178.
doi: 10.3724/SP.J.1146.2011.00980
Abstract:
Based on a binary sequence with ideal two-level autocorrelation with period N=ML+r, a construction of quaternary Low Correlation Zone (LCZ) sequence set is proposed. The parameters of the resultant quaternary LCZ sequence sets such as length of LCZ and set size are flexible. When r0, multiple LCZ sets with the same parameters can be constructed, and when r=0, the set size of LCZ sequence set is optimal or almost optimal with respect to the theoretical bound. As a result, the proposed method can be used to construct more LCZ sequences suitable for QS-CDMA systems.
Based on a binary sequence with ideal two-level autocorrelation with period N=ML+r, a construction of quaternary Low Correlation Zone (LCZ) sequence set is proposed. The parameters of the resultant quaternary LCZ sequence sets such as length of LCZ and set size are flexible. When r0, multiple LCZ sets with the same parameters can be constructed, and when r=0, the set size of LCZ sequence set is optimal or almost optimal with respect to the theoretical bound. As a result, the proposed method can be used to construct more LCZ sequences suitable for QS-CDMA systems.
2012, 34(5): 1179-1184.
doi: 10.3724/SP.J.1146.2011.00982
Abstract:
This paper presents a bidirectional decoding architecture for double binary convolutional turbo code specified in IEEE 802.16m standard to accelerate its decoding speed. The branch metrics matrix is defined to decrease the decoding computational complexity. Furthermore, the forward factor matrix and backward factor matrix are defined, and then the symmetrical property between them is discussed and applied to the bidirectional calculation of forward metrics, backward metrics and a posteriori log-likelihood ratio. Detailed analyses are presented in terms of computational complexity, memory size, decoding speed and bit error rate, which show that computational complexity and memory size of the proposed architecture are not increased, while the decoding speed is one time accelerated as compared with the conventional scheme.
This paper presents a bidirectional decoding architecture for double binary convolutional turbo code specified in IEEE 802.16m standard to accelerate its decoding speed. The branch metrics matrix is defined to decrease the decoding computational complexity. Furthermore, the forward factor matrix and backward factor matrix are defined, and then the symmetrical property between them is discussed and applied to the bidirectional calculation of forward metrics, backward metrics and a posteriori log-likelihood ratio. Detailed analyses are presented in terms of computational complexity, memory size, decoding speed and bit error rate, which show that computational complexity and memory size of the proposed architecture are not increased, while the decoding speed is one time accelerated as compared with the conventional scheme.
2012, 34(5): 1191-1195.
doi: 10.3724/SP.J.1146.2011.00998
Abstract:
For Turbo-like codes, an improved approximate formula of Word Error Rate (WER) is proposed. The formula is simply expressed in the form of the Gaussian Q function, which includes the Signal to Noise Ratio (SNR), the mathematical expectation and the variance of squared radii in decision region, etc. Simulation results show that the error between the proposed formula and Monte Carlo simulation is less than 0.05 dB when the WER is higher than the error floor over Additive White Gaussian Noise (AWGN) channels. Moreover, since the last two parameters connected with the radius of decision region are obtained by simulation, their impacts on the accuracy of the proposed formula are studied. It is shown that the deviation of SNR between the proposed formula and Monte Carlo simulation on the same WER is less than 0.05 dB by using only a few hundreds of radii samples.
For Turbo-like codes, an improved approximate formula of Word Error Rate (WER) is proposed. The formula is simply expressed in the form of the Gaussian Q function, which includes the Signal to Noise Ratio (SNR), the mathematical expectation and the variance of squared radii in decision region, etc. Simulation results show that the error between the proposed formula and Monte Carlo simulation is less than 0.05 dB when the WER is higher than the error floor over Additive White Gaussian Noise (AWGN) channels. Moreover, since the last two parameters connected with the radius of decision region are obtained by simulation, their impacts on the accuracy of the proposed formula are studied. It is shown that the deviation of SNR between the proposed formula and Monte Carlo simulation on the same WER is less than 0.05 dB by using only a few hundreds of radii samples.
2012, 34(5): 1196-1201.
doi: 10.3724/SP.J.1146.2011.01024
Abstract:
In asynchronous Vertical Bell Laboratories Layered Space-Time (V-BLAST) over the nonselective Rayleigh fading channel, the performance of the existing detection algorithms improve slowly as the SNR increasing. In this paper, an iterative Parallel Interference Cancellation (PIC) algorithm based on pre-processing matrix is proposed: the transmitted signal is spread by pre-processing matrix in transmitter to achieve the space-time diversity gain, and low complexity iterative PIC algorithm is used in receiver, which relieves the error propagation by the pre-processing matrix. The performance improvement is verified by simulation. Under the condition of 8 transmit antennas and 4 receive antennas at the BER of 10-3, about 7 dB gain is offered by proposed algorithm compared with traditional ordered successive interference cancellation algorithm.
In asynchronous Vertical Bell Laboratories Layered Space-Time (V-BLAST) over the nonselective Rayleigh fading channel, the performance of the existing detection algorithms improve slowly as the SNR increasing. In this paper, an iterative Parallel Interference Cancellation (PIC) algorithm based on pre-processing matrix is proposed: the transmitted signal is spread by pre-processing matrix in transmitter to achieve the space-time diversity gain, and low complexity iterative PIC algorithm is used in receiver, which relieves the error propagation by the pre-processing matrix. The performance improvement is verified by simulation. Under the condition of 8 transmit antennas and 4 receive antennas at the BER of 10-3, about 7 dB gain is offered by proposed algorithm compared with traditional ordered successive interference cancellation algorithm.
2012, 34(5): 1202-1207.
doi: 10.3724/SP.J.1146.2011.00995
Abstract:
In a wireless multicast communication system, the channel state between each receiver and the specified source (i.e. base station) is different. Therefore, it will result in high delay with too high or too low multicast transmission rate at the source. Moreover, channel states will be varied with node mobility. In this case, multicast rate selection schemes only based on current Channel State Information (CSI) and received Data State Information (DSI) at receivers can not achieve the optimal performance. This paper proposes a multicast rate selection algorithm: Minimize Delay Combine with Prediction of channel states (MDCP) base on CSI and DSI at receivers to minimize transmission delay. Furthermore, MDCP uses network coding to improve the efficiency of data retransmissions. Simulation results show that MDCP can achieve 10%~20% delay gain over the multicast rate selection based the receiver with the worst channel state as well as the multicast rate selection based the receiver with the highest transmission delay and without the prediction of channel states.
In a wireless multicast communication system, the channel state between each receiver and the specified source (i.e. base station) is different. Therefore, it will result in high delay with too high or too low multicast transmission rate at the source. Moreover, channel states will be varied with node mobility. In this case, multicast rate selection schemes only based on current Channel State Information (CSI) and received Data State Information (DSI) at receivers can not achieve the optimal performance. This paper proposes a multicast rate selection algorithm: Minimize Delay Combine with Prediction of channel states (MDCP) base on CSI and DSI at receivers to minimize transmission delay. Furthermore, MDCP uses network coding to improve the efficiency of data retransmissions. Simulation results show that MDCP can achieve 10%~20% delay gain over the multicast rate selection based the receiver with the worst channel state as well as the multicast rate selection based the receiver with the highest transmission delay and without the prediction of channel states.
2012, 34(5): 1208-1213.
doi: 10.3724/SP.J.1146.2011.00919
Abstract:
One of the main requirements of cognitive radio systems is the ability to detect the presence of the primary user with precise accuracy. Previous works on the issue of detection for cognitive radio show that cooperating secondary users in the network can improve spectrum detection performance in practical situations. However, for the cooperative spectrum sensing, a dedicated control channel bandwidth, which transmits the local detection decisions of Secondary Users (SUs) to the data fusion, becomes larger with the number of secondary users increases. To improve further the performance of cooperative spectrum sensing under dedicated control channel bandwidth-limited constraints, a cooperative spectrum sensing is proposed based on reliable secondary user information. More specifically, only the SUs with reliable information are allowed to send their local decisions to the date fusion otherwise the other will send nothing. Furthermore, the performance of the suggested scheme is derived and the numerical results are given. The analysis results indicate that under bandwidth-limited constraints, the sensing performance of suggested scheme outperform the conventional OR cooperative spectrum sensing.
One of the main requirements of cognitive radio systems is the ability to detect the presence of the primary user with precise accuracy. Previous works on the issue of detection for cognitive radio show that cooperating secondary users in the network can improve spectrum detection performance in practical situations. However, for the cooperative spectrum sensing, a dedicated control channel bandwidth, which transmits the local detection decisions of Secondary Users (SUs) to the data fusion, becomes larger with the number of secondary users increases. To improve further the performance of cooperative spectrum sensing under dedicated control channel bandwidth-limited constraints, a cooperative spectrum sensing is proposed based on reliable secondary user information. More specifically, only the SUs with reliable information are allowed to send their local decisions to the date fusion otherwise the other will send nothing. Furthermore, the performance of the suggested scheme is derived and the numerical results are given. The analysis results indicate that under bandwidth-limited constraints, the sensing performance of suggested scheme outperform the conventional OR cooperative spectrum sensing.
2012, 34(5): 1214-1219.
doi: 10.3724/SP.J.1146.2011.00953
Abstract:
The traditional CP-OFDM based multiple access technology still has two drawbacks, i.e., adding cyclic prefix reduces the spectrum efficiency and it is sensitive to the Doppler frequency shift. In this paper, the time-frequency localization of the Extended Gauss Function (EGF) based OFDM/OQAM system is investigated. Consequently, an adaptation scheme in the downlink OFDMA/OQAM system is proposed where the transmitter can choose reasonable spreading factor to match the channel propagation against the inter-symbol interference and inter-carrier interference. Finally, the adaptive scheme is extended to the OFDM/OQAM-based multiple access technology to optimize the system performance. Simulation results prove the effectiveness of the proposed method.
The traditional CP-OFDM based multiple access technology still has two drawbacks, i.e., adding cyclic prefix reduces the spectrum efficiency and it is sensitive to the Doppler frequency shift. In this paper, the time-frequency localization of the Extended Gauss Function (EGF) based OFDM/OQAM system is investigated. Consequently, an adaptation scheme in the downlink OFDMA/OQAM system is proposed where the transmitter can choose reasonable spreading factor to match the channel propagation against the inter-symbol interference and inter-carrier interference. Finally, the adaptive scheme is extended to the OFDM/OQAM-based multiple access technology to optimize the system performance. Simulation results prove the effectiveness of the proposed method.
2012, 34(5): 1220-1225.
doi: 10.3724/SP.J.1146.2011.00748
Abstract:
Most of the study on the beamforming design for Two-Way Relaying Network (TWRN) is based on the reciprocity assumption. Assuming channel is nonreciprocal, this paper designs the beamforming coefficients to maximize the sum-rate of the network subject to the Total Relay Power Constraint (TRPC). To solve this nonconvex problem, a branch-and-bound based algorithm is firstly proposed and the global optimum is proved to be obtained. Secondly, a suboptimal algorithm is proposed. This algorithm assumes the suboptimal solution is the linear combination of two known vector, thus only two real variables need to be optimized, which requires low complexity. Simulation results show that the branch-and-bound algorithm performs better than other existing algorithm. The suboptimal algorithm suffers performance loss compared to the optimal solution, but outperforms other algorithm when the number of relay nodes is relatively small or the average power of relay is relatively small.
Most of the study on the beamforming design for Two-Way Relaying Network (TWRN) is based on the reciprocity assumption. Assuming channel is nonreciprocal, this paper designs the beamforming coefficients to maximize the sum-rate of the network subject to the Total Relay Power Constraint (TRPC). To solve this nonconvex problem, a branch-and-bound based algorithm is firstly proposed and the global optimum is proved to be obtained. Secondly, a suboptimal algorithm is proposed. This algorithm assumes the suboptimal solution is the linear combination of two known vector, thus only two real variables need to be optimized, which requires low complexity. Simulation results show that the branch-and-bound algorithm performs better than other existing algorithm. The suboptimal algorithm suffers performance loss compared to the optimal solution, but outperforms other algorithm when the number of relay nodes is relatively small or the average power of relay is relatively small.
2012, 34(5): 1226-1230.
doi: 10.3724/SP.J.1146.2011.00744
Abstract:
The multistage Clos network or C(m, n, r) is widely deployed in data communications and parallel computing systems because of its scalability. It is well known the network is strictly non-blocking if m2n-1. A new architecture of Multiple Time Slot Clos network (MTS-C (m, n, r)) is proposed in this paper, which is based on fast time slot interchangeable unit and serving for multi-slot traffic. The MTS-C (m, n, r) network keeps the original features while providing better switching performance. A new analytical model assuming a random routing strategy is established, and under this model the blocking probability of the C (m, n, r) network is analyzed. The analytical and simulation results show that a C (m, n, r) network with a small number of middle stage switches m, such as m=n+k, where k is small constant, is almost non-blocking for unicast connections.
The multistage Clos network or C(m, n, r) is widely deployed in data communications and parallel computing systems because of its scalability. It is well known the network is strictly non-blocking if m2n-1. A new architecture of Multiple Time Slot Clos network (MTS-C (m, n, r)) is proposed in this paper, which is based on fast time slot interchangeable unit and serving for multi-slot traffic. The MTS-C (m, n, r) network keeps the original features while providing better switching performance. A new analytical model assuming a random routing strategy is established, and under this model the blocking probability of the C (m, n, r) network is analyzed. The analytical and simulation results show that a C (m, n, r) network with a small number of middle stage switches m, such as m=n+k, where k is small constant, is almost non-blocking for unicast connections.
2012, 34(5): 1231-1238.
doi: 10.3724/SP.J.1146.2011.00914
Abstract:
Network is rigid and close in the traditional technology system, which is not meeting intending abundant different business of scale application. So flexible network technology system facing on service providing is proposed, which change traditional close coupling connection of client business、network service and network foundation facilities to loose coupling connection. Then it can guarantee Quality of Service (QoS) by constituting Reconfigurable Service Carrying Network (RSCN) based on network resource slices. On above technology background, this paper proposes the idea of partition domain schedule after analyzing the requirement of switching fabric from mapping result of RSCN. It constructs crossbar switching resource slicing model by selecting closing part crossbar switching point. It proposes Hybrid Carrying Group Scheduling (HCGS) algorithm. And deduces Smoothed Deficit Round-Robin (SDRR) in the carrying group, input port scheduling algorithm based on timestamp in one carrying domain and output port scheduling algorithm of crossbar switching point. And proves that HCGS algorithm has better time delay and Worst-case Fairness Index (WFI) fairness performance. Then it uses SPES to realize emulation of HCGS algorithm, the result of emulation is that partition domain HCGS algorithm has optimizing time delay and traffic bandwidth fairness performance based on uniform Poisson traffic source, and has 100% throughput based on non-uniform diagonal admissible traffic source.
Network is rigid and close in the traditional technology system, which is not meeting intending abundant different business of scale application. So flexible network technology system facing on service providing is proposed, which change traditional close coupling connection of client business、network service and network foundation facilities to loose coupling connection. Then it can guarantee Quality of Service (QoS) by constituting Reconfigurable Service Carrying Network (RSCN) based on network resource slices. On above technology background, this paper proposes the idea of partition domain schedule after analyzing the requirement of switching fabric from mapping result of RSCN. It constructs crossbar switching resource slicing model by selecting closing part crossbar switching point. It proposes Hybrid Carrying Group Scheduling (HCGS) algorithm. And deduces Smoothed Deficit Round-Robin (SDRR) in the carrying group, input port scheduling algorithm based on timestamp in one carrying domain and output port scheduling algorithm of crossbar switching point. And proves that HCGS algorithm has better time delay and Worst-case Fairness Index (WFI) fairness performance. Then it uses SPES to realize emulation of HCGS algorithm, the result of emulation is that partition domain HCGS algorithm has optimizing time delay and traffic bandwidth fairness performance based on uniform Poisson traffic source, and has 100% throughput based on non-uniform diagonal admissible traffic source.
2012, 34(5): 1239-1245.
doi: 10.3724/SP.J.1146.2011.00977
Abstract:
A Netcoding-based delay-sensitive Broadcast Transmission scheme (NBT) is proposed for Delay Tolerant Mobile Sensor Network (DTMSN). In NBT, the data are batched transmitting from Base Station (BS) and each batch contains finite number of original packets. BS encodes the original packets of one batch with uncorrelated vectors and unicasts them to the different sensor nodes in its coverage, and the sensor nodes exchange encoded packets with each other in flooding mechanism. Because of the packets are encoded, the probability that sensor nodes have the same packets is low and the correlation of data between sensor nodes is reduced too. Simulation results show that the proposed NBT scheme has lower broadcast delay than flooding scheme with the same communication cost under Random WayPoint (RWP) model.
A Netcoding-based delay-sensitive Broadcast Transmission scheme (NBT) is proposed for Delay Tolerant Mobile Sensor Network (DTMSN). In NBT, the data are batched transmitting from Base Station (BS) and each batch contains finite number of original packets. BS encodes the original packets of one batch with uncorrelated vectors and unicasts them to the different sensor nodes in its coverage, and the sensor nodes exchange encoded packets with each other in flooding mechanism. Because of the packets are encoded, the probability that sensor nodes have the same packets is low and the correlation of data between sensor nodes is reduced too. Simulation results show that the proposed NBT scheme has lower broadcast delay than flooding scheme with the same communication cost under Random WayPoint (RWP) model.
2012, 34(5): 1246-1251.
doi: 10.3724/SP.J.1146.2011.00906
Abstract:
In order to resolve the problem of images buffering with huge amount of data quantum in large field TDICCD space camera, the control technology of SDRAM which is a high-speed and large capacity data memory is studied. First, the paper explains the image buffering demand in large field TDICCD space camera, and a SDRAM controller using line enabling driving and a SDRAM controller using arbitration policy are proposed based on the characteristics of CCD image data and that of image buffer. Then, In order to improve reliability for data buffering, a (6,8) error correction algorithm is proposed for the small data situation, and a error correction algorithm of RS (143,127) and RS (142,126) code are proposed for the large data situation. Finally, the verification experiments to CCD imaging system in the prototype machine of XX-X space multi-spectral camera are carried out. The experiments results show that the working frequenc of the two proposed controllers is able to reached 131 MHz. When the system works steadily, the data access speed of line driving controller is 127.08 MBps, and that of arbitration controller is 139.788 MBps. The two proposed error correction algorithms are able to correct 32 b errors in 507 B/row. It can satisfy the space camera data buffering requirements of non-contact, real time and rapid speed.
In order to resolve the problem of images buffering with huge amount of data quantum in large field TDICCD space camera, the control technology of SDRAM which is a high-speed and large capacity data memory is studied. First, the paper explains the image buffering demand in large field TDICCD space camera, and a SDRAM controller using line enabling driving and a SDRAM controller using arbitration policy are proposed based on the characteristics of CCD image data and that of image buffer. Then, In order to improve reliability for data buffering, a (6,8) error correction algorithm is proposed for the small data situation, and a error correction algorithm of RS (143,127) and RS (142,126) code are proposed for the large data situation. Finally, the verification experiments to CCD imaging system in the prototype machine of XX-X space multi-spectral camera are carried out. The experiments results show that the working frequenc of the two proposed controllers is able to reached 131 MHz. When the system works steadily, the data access speed of line driving controller is 127.08 MBps, and that of arbitration controller is 139.788 MBps. The two proposed error correction algorithms are able to correct 32 b errors in 507 B/row. It can satisfy the space camera data buffering requirements of non-contact, real time and rapid speed.
2012, 34(5): 1252-1256.
doi: 10.3724/SP.J.1146.2011.00875
Abstract:
The prospect of memristor application is cheerful with its theory deepening continuously and successful realization, add its unique physical appearance. This paper proposes that memristors have two types: P-type and N-type further. The memristors possess dual characteristics by studing their physical properties. Based on this, linear performance is showed externally by topological link and the selection of parameter between memristors which kept the unique attributes respectively. At the same time, the topology structure of an equivalent analysis circuit and a network of memristor are given. Simulation results show that the method is effective and the conclusion is correct. So that, it opens up new avenues for the theory of memristor and application research, especially for the construction of memristor network.
The prospect of memristor application is cheerful with its theory deepening continuously and successful realization, add its unique physical appearance. This paper proposes that memristors have two types: P-type and N-type further. The memristors possess dual characteristics by studing their physical properties. Based on this, linear performance is showed externally by topological link and the selection of parameter between memristors which kept the unique attributes respectively. At the same time, the topology structure of an equivalent analysis circuit and a network of memristor are given. Simulation results show that the method is effective and the conclusion is correct. So that, it opens up new avenues for the theory of memristor and application research, especially for the construction of memristor network.
2012, 34(5): 1257-1262.
doi: 10.3724/SP.J.1146.2011.00934
Abstract:
A miniaturized multilayer 3D micro/nano ammonia sensor chip is designed and prepared. An ammonia nitrogen measurement system utilizing such a miniaturized sensor chip is constructed. The method of ammonia nitrogen measurement using a miniaturized amperometric ammonia sensor is investigated. The sensor chip is fabricated by micro/nano fabrication technology. Polymer adhesive bonding method is used to achieve the encapsulation of multilayers of the sensor under relatively low temperature condition. Nanoparticles of iridium which possessses excellent electrocatalysis is utilized to enhance the sensitivity. The stability of micro Ag/AgCl reference electrode is evaluated. Measurement of ammonia nitrogen using the self-designed measurement system is presented. The characterizations of the sensor, including relationship between response and sample concentrations, response times, reproducibility and selectivity are demonstrated. A linear calibration curve between 0.5~10 mg/L is obtained with the sensitivity of 1.62 A/(mg/L) and the correlation coefficients of 0.995. The Relative Standard Deviation (RSD) is 5.73%. Meanwhile, the results reveal that the sensor possesses good selectivity.
A miniaturized multilayer 3D micro/nano ammonia sensor chip is designed and prepared. An ammonia nitrogen measurement system utilizing such a miniaturized sensor chip is constructed. The method of ammonia nitrogen measurement using a miniaturized amperometric ammonia sensor is investigated. The sensor chip is fabricated by micro/nano fabrication technology. Polymer adhesive bonding method is used to achieve the encapsulation of multilayers of the sensor under relatively low temperature condition. Nanoparticles of iridium which possessses excellent electrocatalysis is utilized to enhance the sensitivity. The stability of micro Ag/AgCl reference electrode is evaluated. Measurement of ammonia nitrogen using the self-designed measurement system is presented. The characterizations of the sensor, including relationship between response and sample concentrations, response times, reproducibility and selectivity are demonstrated. A linear calibration curve between 0.5~10 mg/L is obtained with the sensitivity of 1.62 A/(mg/L) and the correlation coefficients of 0.995. The Relative Standard Deviation (RSD) is 5.73%. Meanwhile, the results reveal that the sensor possesses good selectivity.
2012, 34(5): 1263-1267.
doi: 10.3724/SP.J.1146.2011.01146
Abstract:
A Space-Time-phase (ST-phase) united processing method is proposed in this paper. It extends the processing domain form space-time to space-time-phase for separating reverberation and targets. Three sub-arrays are firstly constructed. Then, there is a phase difference between the signal parts of sub-array outputs. The value of the phase is depended on the signal arrival orientation. With the phase matching of signals, reverberation and targets can be detached. Unlike the Space-Time Aadaptive Processing (STAP), there is no need to analyze the statistical properties of reverberation and the estimation of reverberation covariance matrix can be overleaped. This will improve the adaptability in non-stationary environment. The simulation data and real data analysis prove that this method can detect out targets in a lower SNR with the compare of conventional method.
A Space-Time-phase (ST-phase) united processing method is proposed in this paper. It extends the processing domain form space-time to space-time-phase for separating reverberation and targets. Three sub-arrays are firstly constructed. Then, there is a phase difference between the signal parts of sub-array outputs. The value of the phase is depended on the signal arrival orientation. With the phase matching of signals, reverberation and targets can be detached. Unlike the Space-Time Aadaptive Processing (STAP), there is no need to analyze the statistical properties of reverberation and the estimation of reverberation covariance matrix can be overleaped. This will improve the adaptability in non-stationary environment. The simulation data and real data analysis prove that this method can detect out targets in a lower SNR with the compare of conventional method.
2012, 34(5): 1268-1270.
doi: 10.3724/SP.J.1146.2011.00930
Abstract:
This paper presents a new method of testing Delta Radar Cross Section (RCS) of Ultra High Frequency Radio Frequency IDentification (UHF RFID) tag using Giga-hertz Transverse ElectroMagnetic (GTEM) cell. Through the theoretical analysis of RFID tags equivalent circuit and its scattering characteristics, the paper demonstrates that the Delta RCS of UHF RFID tag tested in GTEM cell is consist with that tested in free space. Also, the contrast experiments in GTEM cell and anechoic chamber are taken to validate the feasibility and practicability of using GTEM cell to do the Delta RCS test of passive RFID tag.
This paper presents a new method of testing Delta Radar Cross Section (RCS) of Ultra High Frequency Radio Frequency IDentification (UHF RFID) tag using Giga-hertz Transverse ElectroMagnetic (GTEM) cell. Through the theoretical analysis of RFID tags equivalent circuit and its scattering characteristics, the paper demonstrates that the Delta RCS of UHF RFID tag tested in GTEM cell is consist with that tested in free space. Also, the contrast experiments in GTEM cell and anechoic chamber are taken to validate the feasibility and practicability of using GTEM cell to do the Delta RCS test of passive RFID tag.
2012, 34(5): 1185-1190.
doi: 10.3724/SP.J.1146.2011.01360
Abstract:
A Binary Exponential Random Degree Distribution (BERDD) is proposed, the generated fountain codes using BERDD function improve the probability of generating degree 1 in encoding, decreases the probability of degree 1 chasm in decoding, so the decoding complexity is lowed and iteration efficiency is improved. Further, in order to solve the problem of wide transmission bandwidth, a new transmission scheme of compressing fountain coding is proposed based on codebook. It increases bandwidth utilization. Simulation results show that the proposed BERDD function improves decoding efficiency compared with robust soliton degree distribution and binary exponential degree distribution, and the compressing fountain codes reduce transmitting bandwidth effectively in the condition of Rayleigh fading channel.
A Binary Exponential Random Degree Distribution (BERDD) is proposed, the generated fountain codes using BERDD function improve the probability of generating degree 1 in encoding, decreases the probability of degree 1 chasm in decoding, so the decoding complexity is lowed and iteration efficiency is improved. Further, in order to solve the problem of wide transmission bandwidth, a new transmission scheme of compressing fountain coding is proposed based on codebook. It increases bandwidth utilization. Simulation results show that the proposed BERDD function improves decoding efficiency compared with robust soliton degree distribution and binary exponential degree distribution, and the compressing fountain codes reduce transmitting bandwidth effectively in the condition of Rayleigh fading channel.
