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2007 Vol. 29, No. 5
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2007, 29(5): 1017-1022.
doi: 10.3724/SP.J.1146.2005.01350
Abstract:
Multiple cue fusion based tracking is one of the most active research in tracking literature. In this paper, a novel adaptive fusion strategy is proposed for multiple cue fusion, base on two common used fusion rules: product rule and weighted sum rule. This strategy employs particle filtering technique, estimating second order moment of the weighted sample set and computing its Frobenius norm to denote how cues are reliable, and then switch the two fusion rules in time. In practice, the new fusion strategy shows more robustness than traditional single fusion rule.
Multiple cue fusion based tracking is one of the most active research in tracking literature. In this paper, a novel adaptive fusion strategy is proposed for multiple cue fusion, base on two common used fusion rules: product rule and weighted sum rule. This strategy employs particle filtering technique, estimating second order moment of the weighted sample set and computing its Frobenius norm to denote how cues are reliable, and then switch the two fusion rules in time. In practice, the new fusion strategy shows more robustness than traditional single fusion rule.
2007, 29(5): 1023-1026.
doi: 10.3724/SP.J.1146.2006.00165
Abstract:
In this paper, a novel method is proposed to determine the similarity between shots. Firstly, a shot is treated as an ensemble that consists of a sequence of video frames. Shot similarity can be measured by ensemble similarity. Secondly, the original space is mapped to a high dimension space by a nonlinear mapping. In this space, distribution of the ensemble can be assumed as a normal distribution. Finally, by kernel method, the probability distance is computed directly. This distance is equivalent to the ensemble similarity. So, the shot similarity is also obtained. Experimental results show that this method achieves superior performance than the traditional Euclidean distance and histogram intersection methods.
In this paper, a novel method is proposed to determine the similarity between shots. Firstly, a shot is treated as an ensemble that consists of a sequence of video frames. Shot similarity can be measured by ensemble similarity. Secondly, the original space is mapped to a high dimension space by a nonlinear mapping. In this space, distribution of the ensemble can be assumed as a normal distribution. Finally, by kernel method, the probability distance is computed directly. This distance is equivalent to the ensemble similarity. So, the shot similarity is also obtained. Experimental results show that this method achieves superior performance than the traditional Euclidean distance and histogram intersection methods.
2007, 29(5): 1027-1030.
doi: 10.3724/SP.J.1146.2005.01118
Abstract:
A new self-adaptive tracks correlation algorithm is proposed based on the wavelet frame condition and multi-resolution transform. The target track sequences can be decompounded to the whole trend and the detailed character of the tracks to solve tracks correlation problem. This algorithm may adapt well to the maneuvering and non-maneuvering targets tracks correlation. Furthermore, the theory analysis and simulation results show this algorithm is effective.
A new self-adaptive tracks correlation algorithm is proposed based on the wavelet frame condition and multi-resolution transform. The target track sequences can be decompounded to the whole trend and the detailed character of the tracks to solve tracks correlation problem. This algorithm may adapt well to the maneuvering and non-maneuvering targets tracks correlation. Furthermore, the theory analysis and simulation results show this algorithm is effective.
2007, 29(5): 1031-1034.
doi: 10.3724/SP.J.1146.2005.01228
Abstract:
Radial Basis Function-Partial Least Square regression ( RBF-PLS) approach is a rapid and efficient method in constructing Radial Basis Function Network (RBFN), and it has put forward a solution to the problem about the choice of the number and the centers of the radial basis functions. But it is difficult to optimize the spread parameter of the radial basis functions and the number of PLS components extracted. A hybrid coding genetic algorithm, which uses different coding methods for different type of variables is proposed to get the optimal solution for the spread parameter and the number of PLS components. The object function of GA is the performance of fitting and predicting of the model. The approach is successfully applied to radar model recognition.
Radial Basis Function-Partial Least Square regression ( RBF-PLS) approach is a rapid and efficient method in constructing Radial Basis Function Network (RBFN), and it has put forward a solution to the problem about the choice of the number and the centers of the radial basis functions. But it is difficult to optimize the spread parameter of the radial basis functions and the number of PLS components extracted. A hybrid coding genetic algorithm, which uses different coding methods for different type of variables is proposed to get the optimal solution for the spread parameter and the number of PLS components. The object function of GA is the performance of fitting and predicting of the model. The approach is successfully applied to radar model recognition.
2007, 29(5): 1035-1037.
doi: 10.3724/SP.J.1146.2005.01347
Abstract:
The relation of variational image decomposition and wavelet soft threshold was discovered recently by Daubechies and Teschke. A major issue is that thresholded coefficients entail oversmoothing of edges, coefficients set to zero yield Gibbs oscillations in the vicinity of edges, while coefficients remain corrupted generate artifacts. To overcome this problem, piecewise n-degree polynomial threshold and exponential threshold are used to decompose images in this paper, both of which have higher regularity. The near-minimizer of the variational function of image decomposition is obtained. Here, n may be chosen as any positive number and the bigger the degree n is, the better the approximation quality is. Thus, the connection of image variational decomposition and the modified wavelet threshold are obtained. Experimental results demonstrate the effectiveness of the model.
The relation of variational image decomposition and wavelet soft threshold was discovered recently by Daubechies and Teschke. A major issue is that thresholded coefficients entail oversmoothing of edges, coefficients set to zero yield Gibbs oscillations in the vicinity of edges, while coefficients remain corrupted generate artifacts. To overcome this problem, piecewise n-degree polynomial threshold and exponential threshold are used to decompose images in this paper, both of which have higher regularity. The near-minimizer of the variational function of image decomposition is obtained. Here, n may be chosen as any positive number and the bigger the degree n is, the better the approximation quality is. Thus, the connection of image variational decomposition and the modified wavelet threshold are obtained. Experimental results demonstrate the effectiveness of the model.
2007, 29(5): 1038-1040.
doi: 10.3724/SP.J.1146.2005.01549
Abstract:
As a new tool, the wavelet transform has been used successfully in signal denoising. In this paper, the MAP estimate of double Haar wavelet transform coefficients is developed. Also, its application to image denoising is discussed. Examples show that the proposed approach is better than the soft thresholding in image denoising.
As a new tool, the wavelet transform has been used successfully in signal denoising. In this paper, the MAP estimate of double Haar wavelet transform coefficients is developed. Also, its application to image denoising is discussed. Examples show that the proposed approach is better than the soft thresholding in image denoising.
2007, 29(5): 1041-1044.
doi: 10.3724/SP.J.1146.2005.01014
Abstract:
A new method of DOA estimation is presented based on higher-order cumulant. Using the aperture extension property of higher-order cumulant , this method calculates the coordinate and steer vector of virtual sensors from the coordinate and steer vector of actual sensors ,uses the their relation to construct the fourth-order or sixrth-order covariance matrix ,thus using MUSIC algorithm to estimate DOA. This method could extend arbitrary array aperture efficiently based actual array aperture efficiently and estimate the azimuth and elevation of more non-Gaussian independent sources than the number of the actual sensors. It is shown through the simulations that this method is simple and valid for virtual array extension virtual array and increases the resolution of the actual array, the Gaussian noise is suppress significantly and computation cost is significantly reduced.
A new method of DOA estimation is presented based on higher-order cumulant. Using the aperture extension property of higher-order cumulant , this method calculates the coordinate and steer vector of virtual sensors from the coordinate and steer vector of actual sensors ,uses the their relation to construct the fourth-order or sixrth-order covariance matrix ,thus using MUSIC algorithm to estimate DOA. This method could extend arbitrary array aperture efficiently based actual array aperture efficiently and estimate the azimuth and elevation of more non-Gaussian independent sources than the number of the actual sensors. It is shown through the simulations that this method is simple and valid for virtual array extension virtual array and increases the resolution of the actual array, the Gaussian noise is suppress significantly and computation cost is significantly reduced.
2007, 29(5): 1045-1049.
doi: 10.3724/SP.J.1146.2005.01302
Abstract:
A new method of two-dimensional DOA (Direction of Arrival) estimation for low frequency sound source with the non-typical vector acoustic intensity array of small size is proposed. This array consists of 4 sensors on the 3 orthogonal axes, so as to measure the 3 components of the vector acoustic intensity. The azimuth and pitch angles of the sound source can be estimated from the 3 intensity components. The estimation errors, including the finite difference approximation error (FDAE), the instrumentation channel mismatch error (ICME), and the error caused by ambient noise, are studied systematically. Experiments conducted in semi-anechoic chamber show that, after correcting the FDAE and ICME, the precision of DOA estimation in isotropic ambient noise is about 1o. Both theoretical analysis and experimental results validate the effectiveness of this method.
A new method of two-dimensional DOA (Direction of Arrival) estimation for low frequency sound source with the non-typical vector acoustic intensity array of small size is proposed. This array consists of 4 sensors on the 3 orthogonal axes, so as to measure the 3 components of the vector acoustic intensity. The azimuth and pitch angles of the sound source can be estimated from the 3 intensity components. The estimation errors, including the finite difference approximation error (FDAE), the instrumentation channel mismatch error (ICME), and the error caused by ambient noise, are studied systematically. Experiments conducted in semi-anechoic chamber show that, after correcting the FDAE and ICME, the precision of DOA estimation in isotropic ambient noise is about 1o. Both theoretical analysis and experimental results validate the effectiveness of this method.
2007, 29(5): 1050-1053.
doi: 10.3724/SP.J.1146.2005.01270
Abstract:
A new type of genetic algorithm combined the simulated annealing with the advantage of guaranteeing convergence and deciding convergence easily is used for optimization the performance in estimation direction-of-arrival of linear array. In the process of optimization, not only the position of element, but also the number is used as variable. This can provide more degree of freedom to control characters of non-uniform linear array. It can use fewer elements to obtain the estimation accuracy of DOA. And it also can simplify equipment and decrease the computation complexity. The simulation results show that this method has strong ability to find the global optimization solution.
A new type of genetic algorithm combined the simulated annealing with the advantage of guaranteeing convergence and deciding convergence easily is used for optimization the performance in estimation direction-of-arrival of linear array. In the process of optimization, not only the position of element, but also the number is used as variable. This can provide more degree of freedom to control characters of non-uniform linear array. It can use fewer elements to obtain the estimation accuracy of DOA. And it also can simplify equipment and decrease the computation complexity. The simulation results show that this method has strong ability to find the global optimization solution.
2007, 29(5): 1054-1057.
doi: 10.3724/SP.J.1146.2005.01253
Abstract:
Unknown signals are always be treated as outputs of stationary information sources which are easy to be dealt with. So, it is possible to compute multi-fractal spectrum of the signals, which are compared with theoretical results to verify whether the estimation of parameters for a model is correct or not. This paper describes how to compute the multi-fractal spectrum and other problems concerning the methods. Applying the methods to the analysis of DNA sequences shows that, in a sense, genomic sequence can be viewed as outputs of a stationary information source.
Unknown signals are always be treated as outputs of stationary information sources which are easy to be dealt with. So, it is possible to compute multi-fractal spectrum of the signals, which are compared with theoretical results to verify whether the estimation of parameters for a model is correct or not. This paper describes how to compute the multi-fractal spectrum and other problems concerning the methods. Applying the methods to the analysis of DNA sequences shows that, in a sense, genomic sequence can be viewed as outputs of a stationary information source.
2007, 29(5): 1058-1060.
doi: 10.3724/SP.J.1146.2005.01444
Abstract:
A new algorithm is proposed for Time Difference of Arrival(TDOA) estimation from a train of coherent pulses in additive Gaussian noise, named it as frequency compensation TDOA estimation. It is shown to be a algorithm with small estimation error, small computation and good applicability. Simulations are given to support these conclusion.
A new algorithm is proposed for Time Difference of Arrival(TDOA) estimation from a train of coherent pulses in additive Gaussian noise, named it as frequency compensation TDOA estimation. It is shown to be a algorithm with small estimation error, small computation and good applicability. Simulations are given to support these conclusion.
2007, 29(5): 1061-1064.
doi: 10.3724/SP.J.1146.2005.01360
Abstract:
Because of different working ways between BiSAR and SAR, this paper analyzes the feasibility of rebound jamming against BiSAR and the effective of the jamming is proved. The model of rebound jamming against BiSAR is given. The jamming principle and effect are described. As for Normal Rebound Jamming (NRJ), the paper analyzes the focus protection area. Theoretic analysis is verified via computer simulations.
Because of different working ways between BiSAR and SAR, this paper analyzes the feasibility of rebound jamming against BiSAR and the effective of the jamming is proved. The model of rebound jamming against BiSAR is given. The jamming principle and effect are described. As for Normal Rebound Jamming (NRJ), the paper analyzes the focus protection area. Theoretic analysis is verified via computer simulations.
2007, 29(5): 1065-1068.
doi: 10.3724/SP.J.1146.2005.01283
Abstract:
In the high resolution SAR, the effect of motion error at the azimuth direction is more severe. Though the traditional Phase Gradient Autofocus(PGA) algorithm can be used to estimate the motion error, the iterative phase correction has to be done. The huge computation makes it difficult to be used in real time image processing. In order to meet the request of real time imaging of high resolution SAR, the Shift And Correlate (SAC) algorithm, Shift And Correlate of Gate Strategy (SACGS) algorithm, PGA algorithm and Range Doppler (RD) algorithm are combined in this paper. With the new combined algorithm, the iterative operation can be reduced or even omitted. At the same time, the computation and the precision request for the initial motion parameter is decreased. The simulation and the result of imaging for real SAR data can validate the new algorithm.
In the high resolution SAR, the effect of motion error at the azimuth direction is more severe. Though the traditional Phase Gradient Autofocus(PGA) algorithm can be used to estimate the motion error, the iterative phase correction has to be done. The huge computation makes it difficult to be used in real time image processing. In order to meet the request of real time imaging of high resolution SAR, the Shift And Correlate (SAC) algorithm, Shift And Correlate of Gate Strategy (SACGS) algorithm, PGA algorithm and Range Doppler (RD) algorithm are combined in this paper. With the new combined algorithm, the iterative operation can be reduced or even omitted. At the same time, the computation and the precision request for the initial motion parameter is decreased. The simulation and the result of imaging for real SAR data can validate the new algorithm.
2007, 29(5): 1069-1072.
doi: 10.3724/SP.J.1146.2005.01359
Abstract:
A novel Markow Random Field(MRF)-based segmentation method for SAR images is proposed. The method involves the intensity differences and the distances between pixels based on the traditional MRF potential function. It utilizes more spacial information of SAR image in the potential function model. The segmentation issue is transformed to the Maximum A Posteriori (MAP) by Beyes theorem. Finally, the Iterative Conditional Model (ICM) is employed to find out the solution of MAP problem. In the experiments, the method is compared with the traditional MRF segmentation method using ICM and simulate annealing, the results showed that this method is better than the traditional MRF one both in noise filtering and miss-classification ratio.
A novel Markow Random Field(MRF)-based segmentation method for SAR images is proposed. The method involves the intensity differences and the distances between pixels based on the traditional MRF potential function. It utilizes more spacial information of SAR image in the potential function model. The segmentation issue is transformed to the Maximum A Posteriori (MAP) by Beyes theorem. Finally, the Iterative Conditional Model (ICM) is employed to find out the solution of MAP problem. In the experiments, the method is compared with the traditional MRF segmentation method using ICM and simulate annealing, the results showed that this method is better than the traditional MRF one both in noise filtering and miss-classification ratio.
2007, 29(5): 1073-1076.
doi: 10.3724/SP.J.1146.2005.01406
Abstract:
ATI-SAR system requires that the phase characteristic of the two channels is precisely matched. This paper analyzes the phase error of ATI-SAR system, gives the mathematic model, proposes a simple phase calibration method for ATI-SAR system based on Least Square Estimation (LSE) and wavelet-denoising and gives the calibration flow. The simulation results demonstrated that the phase error of ATI-SAR system is removed by this method. This method does require any knowledge of the platform velocity and actual crab angle. The problem of wrapped interferometric phases can be resolved by iterative of this method.
ATI-SAR system requires that the phase characteristic of the two channels is precisely matched. This paper analyzes the phase error of ATI-SAR system, gives the mathematic model, proposes a simple phase calibration method for ATI-SAR system based on Least Square Estimation (LSE) and wavelet-denoising and gives the calibration flow. The simulation results demonstrated that the phase error of ATI-SAR system is removed by this method. This method does require any knowledge of the platform velocity and actual crab angle. The problem of wrapped interferometric phases can be resolved by iterative of this method.
2007, 29(5): 1077-1082.
doi: 10.3724/SP.J.1146.2005.01210
Abstract:
To achieve wide-swath and full azimuth resolution in space-borne Synthetic Aperture Radar (SAR), the satellite can take low Pulse Repetition Frequency (PRF) and small aperture in azimuth. Then azimuth ambiguities is inevitable. The constellation of small satellites can be used to remove azimuth ambiguities. In this paper, two satellites fly in a line is used to settle the problem. Both of the satellites transmit a Linear Frequency Modulation (LFM) signal of the same center frequency, but one is positive frequency modulation, the other is negative frequency modulation. The three phase centers resulted from the two satellites can be used to remove three azimuth ambiguities through space-time processing. An innovative method is proposed to simplify the calculating of the filter weight vector. Simulations show the validity of these methods.
To achieve wide-swath and full azimuth resolution in space-borne Synthetic Aperture Radar (SAR), the satellite can take low Pulse Repetition Frequency (PRF) and small aperture in azimuth. Then azimuth ambiguities is inevitable. The constellation of small satellites can be used to remove azimuth ambiguities. In this paper, two satellites fly in a line is used to settle the problem. Both of the satellites transmit a Linear Frequency Modulation (LFM) signal of the same center frequency, but one is positive frequency modulation, the other is negative frequency modulation. The three phase centers resulted from the two satellites can be used to remove three azimuth ambiguities through space-time processing. An innovative method is proposed to simplify the calculating of the filter weight vector. Simulations show the validity of these methods.
2007, 29(5): 1083-1086.
doi: 10.3724/SP.J.1146.2005.01981
Abstract:
This paper studies the performances of GPS signals as the illuminator of bistatic passive radar. The radar system structure and signal model are firstly developed, then the detection range and signal ambiguity are analyzed, and finally computer simulations are used to evaluate the performances. Theoretical analyses and simulation results reveal that the GPS signals are applicable as the passive radar signals.
This paper studies the performances of GPS signals as the illuminator of bistatic passive radar. The radar system structure and signal model are firstly developed, then the detection range and signal ambiguity are analyzed, and finally computer simulations are used to evaluate the performances. Theoretical analyses and simulation results reveal that the GPS signals are applicable as the passive radar signals.
2007, 29(5): 1087-1091.
doi: 10.3724/SP.J.1146.2005.01211
Abstract:
At high grazing angles, the sea clutter background has a strong impact on 3-D imaging. A method for Radon transform based sea clutter suppression is given in this paper. ISAR technique is used to get two-dimension image of the target firstly. Then angular motion compensation and Radon transformation are performed to the ISAR image. A novel search algorithm based on the edge detection is used to divide the target from the sea clutter in the end. The result of the 3-D imaging shows the effectiveness of the new method for sea clutter suppression.
At high grazing angles, the sea clutter background has a strong impact on 3-D imaging. A method for Radon transform based sea clutter suppression is given in this paper. ISAR technique is used to get two-dimension image of the target firstly. Then angular motion compensation and Radon transformation are performed to the ISAR image. A novel search algorithm based on the edge detection is used to divide the target from the sea clutter in the end. The result of the 3-D imaging shows the effectiveness of the new method for sea clutter suppression.
2007, 29(5): 1092-1095.
doi: 10.3724/SP.J.1146.2005.01394
Abstract:
A new method based on frequency domain masking and fractional correlation is presented for Anti Radio Missile (ARM) detection. The method adopts the frequency domain masking technique to mask the peak fields of the radar echos Fourier transform data, and uses the fractional correlation comprising of Fractional Fourier Transform (FrFT) and inverse Fourier transform to detect the ARM only in one-dimensional searching. As the FrFT can be implemented via fast Fourier transform, and the multichannel phase compensation and two-dimensional search are no longer needed, the computation is greatly reduced. Simulation results show that an accurate detection is achieved in a #61485;10dB ARM signal to noise ration, which implies a reliable early warning of ARM launching.
A new method based on frequency domain masking and fractional correlation is presented for Anti Radio Missile (ARM) detection. The method adopts the frequency domain masking technique to mask the peak fields of the radar echos Fourier transform data, and uses the fractional correlation comprising of Fractional Fourier Transform (FrFT) and inverse Fourier transform to detect the ARM only in one-dimensional searching. As the FrFT can be implemented via fast Fourier transform, and the multichannel phase compensation and two-dimensional search are no longer needed, the computation is greatly reduced. Simulation results show that an accurate detection is achieved in a #61485;10dB ARM signal to noise ration, which implies a reliable early warning of ARM launching.
2007, 29(5): 1096-1100.
doi: 10.3724/SP.J.1146.2005.01002
Abstract:
A method based on fractional spectral subtraction for speech enhancement (FSS) is proposed. It applies FRFT (FRactional Fourier Transform) to noisy speech, the estimated fractional noise spectrum is then subtracted from the derived fractional speech-noise spectrum. Finally, the denoised speech is obtained by inverse fractional Fourier transform. Theory analysis indicates that the new method can find an optimal fractional order, which can best separate speech for noisy data in the fractional Fourier domain. The result is that the performance of the enhanced speech is effectively improved. Computer simulation shows that the SNR improvement amount and Itakura distance decrease amount of the proposed method are superior to those of Spectral Subtraction (SS) for male/female speech corrupted by additive white Gaussian noise. In addition, the music noise of the enhanced speech is remarkably suppressed.
A method based on fractional spectral subtraction for speech enhancement (FSS) is proposed. It applies FRFT (FRactional Fourier Transform) to noisy speech, the estimated fractional noise spectrum is then subtracted from the derived fractional speech-noise spectrum. Finally, the denoised speech is obtained by inverse fractional Fourier transform. Theory analysis indicates that the new method can find an optimal fractional order, which can best separate speech for noisy data in the fractional Fourier domain. The result is that the performance of the enhanced speech is effectively improved. Computer simulation shows that the SNR improvement amount and Itakura distance decrease amount of the proposed method are superior to those of Spectral Subtraction (SS) for male/female speech corrupted by additive white Gaussian noise. In addition, the music noise of the enhanced speech is remarkably suppressed.
2007, 29(5): 1101-1105.
doi: 10.3724/SP.J.1146.2005.00829
Abstract:
This paper proposes a novel joint iterative channel estimation and symbol detection algorithm based on MMSE criterion for MIMO-OFDM systems. The performance of the joint iterative algorithm mainly depends on initial channel estimator and iterative algorithm. Therefore, a new channel estimation algorithm is developed based on Time-Frequency Transform(TFT), then the joint iterative channel estimation and symbol detection algorithm according to MMSE criterion by using initial channel estimated values and detected symbols is advanced. Analysis and simulation illustrate that the novel joint iterative algorithm improves remarkably performance both quasi-static and fast time-varying channels.
This paper proposes a novel joint iterative channel estimation and symbol detection algorithm based on MMSE criterion for MIMO-OFDM systems. The performance of the joint iterative algorithm mainly depends on initial channel estimator and iterative algorithm. Therefore, a new channel estimation algorithm is developed based on Time-Frequency Transform(TFT), then the joint iterative channel estimation and symbol detection algorithm according to MMSE criterion by using initial channel estimated values and detected symbols is advanced. Analysis and simulation illustrate that the novel joint iterative algorithm improves remarkably performance both quasi-static and fast time-varying channels.
2007, 29(5): 1106-1109.
doi: 10.3724/SP.J.1146.2005.01251
Abstract:
An 800/920/1200bps modified speech coder based on the Multi-Band Excitation (MBE) speech model is presented. The two stage discrete cosine transformation coding scheme has been used to quantize the spectral magnitude parameters changing frame-by-frame adaptively in the speech coder. The coded bit rate of speech is largely reduced and that make it possible the implementation of 800~1200bps MBE speech coder. This paper focuses on the design of two stage discrete cosine transformation coding scheme and hardware implementation based on DSP processor.
An 800/920/1200bps modified speech coder based on the Multi-Band Excitation (MBE) speech model is presented. The two stage discrete cosine transformation coding scheme has been used to quantize the spectral magnitude parameters changing frame-by-frame adaptively in the speech coder. The coded bit rate of speech is largely reduced and that make it possible the implementation of 800~1200bps MBE speech coder. This paper focuses on the design of two stage discrete cosine transformation coding scheme and hardware implementation based on DSP processor.
2007, 29(5): 1110-1114.
doi: 10.3724/SP.J.1146.2005.01377
Abstract:
A new polarization smoothing algorithm is proposed for the 2-D direction finding of coherent cyclostationary signals. By sufficiently utilizing the cyclostationarity and polarization diversity, the proposed method increases the number of coherent sources that can be estimated and has the signal-selectivity and noise-robustness, without impacting the aperture of the sensors array. All parameters match automatically in the estimation process. Simulations are presented to show the performance of the algorithm.
A new polarization smoothing algorithm is proposed for the 2-D direction finding of coherent cyclostationary signals. By sufficiently utilizing the cyclostationarity and polarization diversity, the proposed method increases the number of coherent sources that can be estimated and has the signal-selectivity and noise-robustness, without impacting the aperture of the sensors array. All parameters match automatically in the estimation process. Simulations are presented to show the performance of the algorithm.
2007, 29(5): 1115-1118.
doi: 10.3724/SP.J.1146.2005.01303
Abstract:
There are various structures of good TCM codes. And based on the trellis map, the most possible structure of good TCM codes is analyzed. From the results, a construction algorithm is then designed. Since the searching space is greatly reduced, this method has higher efficiency and can produce codes of high performance compared with the classic algorithm.
There are various structures of good TCM codes. And based on the trellis map, the most possible structure of good TCM codes is analyzed. From the results, a construction algorithm is then designed. Since the searching space is greatly reduced, this method has higher efficiency and can produce codes of high performance compared with the classic algorithm.
2007, 29(5): 1119-1123.
doi: 10.3724/SP.J.1146.2005.01214
Abstract:
This paper investigates a serial concatenation of Low-Density Parity-Check (LDPC) codes with Minimum Shift Keying (MSK) when the receiver employs iterative decoding and demodulation. First, the RCPE and NRCPE modes of the MSK modulator are described, then the error correlation in the Recursive CPE (RCPE) MSK demodulator and the overall loop in the joint Tanner graph are analyzed. Finally a new design rule is developed which allows the serially concatenated system not to employ interleavers. Simulation results show that the proposed design rule reduces the impact of the error correlation in a simple and effective way.
This paper investigates a serial concatenation of Low-Density Parity-Check (LDPC) codes with Minimum Shift Keying (MSK) when the receiver employs iterative decoding and demodulation. First, the RCPE and NRCPE modes of the MSK modulator are described, then the error correlation in the Recursive CPE (RCPE) MSK demodulator and the overall loop in the joint Tanner graph are analyzed. Finally a new design rule is developed which allows the serially concatenated system not to employ interleavers. Simulation results show that the proposed design rule reduces the impact of the error correlation in a simple and effective way.
2007, 29(5): 1124-1126.
doi: 10.3724/SP.J.1146.2005.01254
Abstract:
In the last ten more years, cyclic codes over finite rings have become a hot issue for coding theorists.It is proved that R[x]/xn-1 is not a principal ideal domain, where R=2+u2 with u2=0, and n=2e. The nonzero ideals of R[x]/xn-1 are discussed in three cases and the expressions of the uniquely determined generators of the cyclic codes are given. An estimate of upper bound of Lee distance of cyclic codes over R is also given.
In the last ten more years, cyclic codes over finite rings have become a hot issue for coding theorists.It is proved that R[x]/xn-1 is not a principal ideal domain, where R=2+u2 with u2=0, and n=2e. The nonzero ideals of R[x]/xn-1 are discussed in three cases and the expressions of the uniquely determined generators of the cyclic codes are given. An estimate of upper bound of Lee distance of cyclic codes over R is also given.
2007, 29(5): 1127-1130.
doi: 10.3724/SP.J.1146.2005.01115
Abstract:
It is firstly proved that the non-independence among the candidates used in the Interleaved partitioning Partial Transmit Sequences (IPTS) results in the lower performance of IPTS, compared to the Adjacent partitioning PTS (APTS). More independent candidates can be created and better performance can be gained using subblocks and their conjugate versions in the proposed Modified IPTS (MIPTS). The simulation results show the MIPTS has similar PAPR reduction performance as APTS without over-sampling or is superior to APTS with over-sampling.
It is firstly proved that the non-independence among the candidates used in the Interleaved partitioning Partial Transmit Sequences (IPTS) results in the lower performance of IPTS, compared to the Adjacent partitioning PTS (APTS). More independent candidates can be created and better performance can be gained using subblocks and their conjugate versions in the proposed Modified IPTS (MIPTS). The simulation results show the MIPTS has similar PAPR reduction performance as APTS without over-sampling or is superior to APTS with over-sampling.
2007, 29(5): 1131-1135.
doi: 10.3724/SP.J.1146.2005.00989
Abstract:
The shift-variant property of discrete wavelet transform makes wavelet-domain motion estimation inaccurate. In order to overcome the shift-variant property, a 2-channel high-pass filtering method and a wavelet-domain motion estimation algorithm are presented. The experiment results demonstrate validity of the new method, and indicate the new wavelet-domain motion estimation has comparable performance and low calculated complexity. Therefore, this is likely appealing for the wavelet video coding applications.
The shift-variant property of discrete wavelet transform makes wavelet-domain motion estimation inaccurate. In order to overcome the shift-variant property, a 2-channel high-pass filtering method and a wavelet-domain motion estimation algorithm are presented. The experiment results demonstrate validity of the new method, and indicate the new wavelet-domain motion estimation has comparable performance and low calculated complexity. Therefore, this is likely appealing for the wavelet video coding applications.
2007, 29(5): 1136-1139.
doi: 10.3724/SP.J.1146.2005.01378
Abstract:
Based on the study of the relationship between the bit rate for video coding and the content complexity, this paper presents a new quadratic rate distortion model for video coding, which retains the constant term in Taylor series. Through introducing the content complexity term reasonably, this model provides an accurate description of the rate distortion characteristic of the practical source. The performance of the model is evaluated through analyzing large amount of experimental data. This model can be used in rate control schemes for video coding and other applications where rate distortion model is in demand, by which the rate distortion performance of video coding systems can be improved.
Based on the study of the relationship between the bit rate for video coding and the content complexity, this paper presents a new quadratic rate distortion model for video coding, which retains the constant term in Taylor series. Through introducing the content complexity term reasonably, this model provides an accurate description of the rate distortion characteristic of the practical source. The performance of the model is evaluated through analyzing large amount of experimental data. This model can be used in rate control schemes for video coding and other applications where rate distortion model is in demand, by which the rate distortion performance of video coding systems can be improved.
2007, 29(5): 1140-1144.
doi: 10.3724/SP.J.1146.2006.00293
Abstract:
Interference spectral images have their own features. The correlations between the spectral lines are weak. And the data in a spectral line have particularity, that is, the data vary abruptly in the main district and the rest data change monotonously. On the basis of analyzing the particularity, a novel method for data classification is proposed. The data of a spectral line are decomposed to two classes, called main-interference class and no main-interference class. And a similarity-based match method is presented for the data of main-interference class, while the data of no main-interference class is processed by another method called 2-order curve-fitting algorithm. The data of a spectral line can be approached appropriately in the ways discussed above, which avails for image compression. The experimental results show that the output rate decreases by 0.2-0.4bpp for lossless compression and also can improve the loss compression efficiency.
Interference spectral images have their own features. The correlations between the spectral lines are weak. And the data in a spectral line have particularity, that is, the data vary abruptly in the main district and the rest data change monotonously. On the basis of analyzing the particularity, a novel method for data classification is proposed. The data of a spectral line are decomposed to two classes, called main-interference class and no main-interference class. And a similarity-based match method is presented for the data of main-interference class, while the data of no main-interference class is processed by another method called 2-order curve-fitting algorithm. The data of a spectral line can be approached appropriately in the ways discussed above, which avails for image compression. The experimental results show that the output rate decreases by 0.2-0.4bpp for lossless compression and also can improve the loss compression efficiency.
2007, 29(5): 1145-1149.
doi: 10.3724/SP.J.1146.2005.01257
Abstract:
An improved channel estimation scheme based on estimation of parameters is presented for frequency-selective MIMO channels. In the algorithm, the propagation delays and the angles of multipath are firstly estimated by a modified TST-MUSIC algorithm. With the information of multipath delays and angles, an estimator based on parametric channel model is derived and the estimators performance is analysed. Simulation results show that the method can effectively decrease the dimension of estimated parameters, consequently has much better performance than the nonparametric least square estimator.
An improved channel estimation scheme based on estimation of parameters is presented for frequency-selective MIMO channels. In the algorithm, the propagation delays and the angles of multipath are firstly estimated by a modified TST-MUSIC algorithm. With the information of multipath delays and angles, an estimator based on parametric channel model is derived and the estimators performance is analysed. Simulation results show that the method can effectively decrease the dimension of estimated parameters, consequently has much better performance than the nonparametric least square estimator.
2007, 29(5): 1150-1154.
doi: 10.3724/SP.J.1146.2005.00807
Abstract:
The future OFDM systems are expected to operate at high transmit frequencies, at high capacities, at high levels of mobility, and the traditional one-tap equalizer is not applicable any more. In this paper, a novel frequency-domain Turbo equalization (FTE) technique for OFDM systems over doubly-selective channels is presented based on the analysis of the ICI generation mechanism. Simulation results indicate the presented approach has significant BER performance and complexity advantages, can mitigate ICI effectively over doubly-selective channels.
The future OFDM systems are expected to operate at high transmit frequencies, at high capacities, at high levels of mobility, and the traditional one-tap equalizer is not applicable any more. In this paper, a novel frequency-domain Turbo equalization (FTE) technique for OFDM systems over doubly-selective channels is presented based on the analysis of the ICI generation mechanism. Simulation results indicate the presented approach has significant BER performance and complexity advantages, can mitigate ICI effectively over doubly-selective channels.
2007, 29(5): 1155-1158.
doi: 10.3724/SP.J.1146.2005.01229
Abstract:
OFDMA is the extension of OFDM. Similar to OFDM, and it is also very sensitive to Carrier Frequency Offset (CFO). In this paper, a pilot-assisted carrier frequency offset estimation algorithm and a low-complexity CFO compensation algorithm are presented. The simulation results illustrate that this algorithm is low-complexity and proposes a high accuracy.
OFDMA is the extension of OFDM. Similar to OFDM, and it is also very sensitive to Carrier Frequency Offset (CFO). In this paper, a pilot-assisted carrier frequency offset estimation algorithm and a low-complexity CFO compensation algorithm are presented. The simulation results illustrate that this algorithm is low-complexity and proposes a high accuracy.
2007, 29(5): 1159-1162.
doi: 10.3724/SP.J.1146.2005.01209
Abstract:
The analysis of correlation matrix of the received signal proves that the energy of narrowband interference is compressed in the low rank subspace, interference subspace, and the energy of DSSS signal and AWGN uniformly distribute. The narrowband interference suppression can be realized by tracking the interference subspace and projecting the received signal vector to the orthogonal subspace of it. The algorithm proposed here is low complexity, numerical stability and better performance than traditional Adaptive Transversal Filter (ATF).
The analysis of correlation matrix of the received signal proves that the energy of narrowband interference is compressed in the low rank subspace, interference subspace, and the energy of DSSS signal and AWGN uniformly distribute. The narrowband interference suppression can be realized by tracking the interference subspace and projecting the received signal vector to the orthogonal subspace of it. The algorithm proposed here is low complexity, numerical stability and better performance than traditional Adaptive Transversal Filter (ATF).
2007, 29(5): 1163-1167.
doi: 10.3724/SP.J.1146.2005.01011
Abstract:
This paper presents a new frequency hopping system in HF (High Frequency) bands, which is called Differential Frequency Hopping (DFH) system. The frequency transition function and the method of signal detection are the key technologies in this system. The performance of DFH with partial band jamming and additive white Gaussian noise over the Rayleigh fading channel by using product-combining receiver is analyzed in theory, and the corresponding simulation results are given. All these prove that the anti-jam performance of DFH system with product-combining receiver is much better than that with linear-combining receiver.
This paper presents a new frequency hopping system in HF (High Frequency) bands, which is called Differential Frequency Hopping (DFH) system. The frequency transition function and the method of signal detection are the key technologies in this system. The performance of DFH with partial band jamming and additive white Gaussian noise over the Rayleigh fading channel by using product-combining receiver is analyzed in theory, and the corresponding simulation results are given. All these prove that the anti-jam performance of DFH system with product-combining receiver is much better than that with linear-combining receiver.
2007, 29(5): 1168-1172.
doi: 10.3724/SP.J.1146.2005.01245
Abstract:
By introducing full-rate Space-Time Block Coding (STBC) scheme, a Full-rate Space-Time Block Coded CDMA (FSTBC-CDMA) system model is given in this paper. Considering that existing space-time coded CDMA system has high decoding complexity, a low-complexity multiuser receiver scheme is also proposed. The scheme can make full use of the complex orthogonality of STBC to simply the high decoding complexity of the existing scheme after multiuser detection method like is employed to suppress multiuser interference effectively; it has linear decoding complexity when compared with existing scheme (it has exponential decoding complexity). Moreover, compared with full-diversity space-time block coded CDMA, the FSTBC-CDMA system can implement full rate, low complexity and partial diversity, has more spatial redundant information. Thus the concatenation of channel coding can effectively compensate for the performance loss due to partial diversity. Simulation results also show that on the condition of same system throughput and concatenation of channel code, the proposed FSTBC-CDMA system has lower Bit Error Rate (BER) than those low-rate and full-diversity space-time block coded CDMA system.
By introducing full-rate Space-Time Block Coding (STBC) scheme, a Full-rate Space-Time Block Coded CDMA (FSTBC-CDMA) system model is given in this paper. Considering that existing space-time coded CDMA system has high decoding complexity, a low-complexity multiuser receiver scheme is also proposed. The scheme can make full use of the complex orthogonality of STBC to simply the high decoding complexity of the existing scheme after multiuser detection method like is employed to suppress multiuser interference effectively; it has linear decoding complexity when compared with existing scheme (it has exponential decoding complexity). Moreover, compared with full-diversity space-time block coded CDMA, the FSTBC-CDMA system can implement full rate, low complexity and partial diversity, has more spatial redundant information. Thus the concatenation of channel coding can effectively compensate for the performance loss due to partial diversity. Simulation results also show that on the condition of same system throughput and concatenation of channel code, the proposed FSTBC-CDMA system has lower Bit Error Rate (BER) than those low-rate and full-diversity space-time block coded CDMA system.
2007, 29(5): 1173-1176.
doi: 10.3724/SP.J.1146.2005.01237
Abstract:
The four round MISTY-type and the three round dual MISTY-type transformation are optimized by replacing the first round pseudorandom permutation with XOR-universal permutation and employing identical pseudorandom permutation in the second and the third round. Thus the running time is shortened and the number of keys are saved by reducing the number of pseudorandom permutation. Hence the running cost is debased greatly. At the same time, the security remains.
The four round MISTY-type and the three round dual MISTY-type transformation are optimized by replacing the first round pseudorandom permutation with XOR-universal permutation and employing identical pseudorandom permutation in the second and the third round. Thus the running time is shortened and the number of keys are saved by reducing the number of pseudorandom permutation. Hence the running cost is debased greatly. At the same time, the security remains.
2007, 29(5): 1177-1181.
doi: 10.3724/SP.J.1146.2005.01236
Abstract:
A multi-service traitor tracing scheme on LIFP(Large Integer Factoring Problem) is proposed，the essential idea of which is that an equation based on LIFP is constructed and a parameter is introduced to transfer service private-key. In decryption procedure, the session key can be obtained by the equation and the service private-key. Compared with the existing two traitor tracing schemes, this scheme has many advantages such as multi-service, black-box traitor tracing, ciphertexts of constant size, adding or revoking users, forward-security and backward-security. Furthermore, its whole capabilities are better than that of the existing ones.
A multi-service traitor tracing scheme on LIFP(Large Integer Factoring Problem) is proposed，the essential idea of which is that an equation based on LIFP is constructed and a parameter is introduced to transfer service private-key. In decryption procedure, the session key can be obtained by the equation and the service private-key. Compared with the existing two traitor tracing schemes, this scheme has many advantages such as multi-service, black-box traitor tracing, ciphertexts of constant size, adding or revoking users, forward-security and backward-security. Furthermore, its whole capabilities are better than that of the existing ones.
2007, 29(5): 1182-1186.
doi: 10.3724/SP.J.1146.2005.01290
Abstract:
This paper proposes the alarm correlation and fault identification based on Bayesian networks in communication networks. At first, the basic concepts of Bayesian networks are introduced. Then the paper presents an approach for modeling large communication networks that are divided into their constituting sub-networks. And the causal relation is used to model the functional relationship among the sub-networks. The paper discusses how to construct Bayesian networks from the causal relation and presents a distributed alarm correlation framework based on CORBA. Finally, the realization and results of alarm correlation and fault identification is discussed in SDH over DWDM systems. The experimentation has proved that using Bayesian network based alarm correlation is benefit to detect and localize the root faults in communication networks.
This paper proposes the alarm correlation and fault identification based on Bayesian networks in communication networks. At first, the basic concepts of Bayesian networks are introduced. Then the paper presents an approach for modeling large communication networks that are divided into their constituting sub-networks. And the causal relation is used to model the functional relationship among the sub-networks. The paper discusses how to construct Bayesian networks from the causal relation and presents a distributed alarm correlation framework based on CORBA. Finally, the realization and results of alarm correlation and fault identification is discussed in SDH over DWDM systems. The experimentation has proved that using Bayesian network based alarm correlation is benefit to detect and localize the root faults in communication networks.
2007, 29(5): 1187-1190.
doi: 10.3724/SP.J.1146.2005.01240
Abstract:
Link Criticality Routing Algorithm (LCRA) is presented for Multi-Protocol Label Switch (MPLS) traffic engineering. It defines the link weight and chooses a path for a Label Switch Path set-up request through defining the average expectation load of links and determining the criticality of links. The main objective of LCRA is to swiftly set up paths as many as possible with bandwidth guaranteed, and make these paths go through evenly the network. Simulation shows the algorithm is better than other algorithms in reject ratio of the traffic requests and performance of rerouting the traffic requests when a link is failure, especially in computing time cost.
Link Criticality Routing Algorithm (LCRA) is presented for Multi-Protocol Label Switch (MPLS) traffic engineering. It defines the link weight and chooses a path for a Label Switch Path set-up request through defining the average expectation load of links and determining the criticality of links. The main objective of LCRA is to swiftly set up paths as many as possible with bandwidth guaranteed, and make these paths go through evenly the network. Simulation shows the algorithm is better than other algorithms in reject ratio of the traffic requests and performance of rerouting the traffic requests when a link is failure, especially in computing time cost.
2007, 29(5): 1191-1193.
doi: 10.3724/SP.J.1146.2005.01443
Abstract:
Based on control theory, a Proportional-Integral (PI) controller is designed which has a character of fast response. Consequently, a new Active Queue Management (AQM) scheme called Active PI algorithm (A-PI) is proposed, which employed double sets of parameters applying one set of parameters for fast response and the other for achieving queues stability. A-PI controller uses threshold to shift parameter smoothly, and it can be implemented easily. Analysis and simulation results show that under various network conditions A-PI controller has a fast response and a good performance in stability.
Based on control theory, a Proportional-Integral (PI) controller is designed which has a character of fast response. Consequently, a new Active Queue Management (AQM) scheme called Active PI algorithm (A-PI) is proposed, which employed double sets of parameters applying one set of parameters for fast response and the other for achieving queues stability. A-PI controller uses threshold to shift parameter smoothly, and it can be implemented easily. Analysis and simulation results show that under various network conditions A-PI controller has a fast response and a good performance in stability.
2007, 29(5): 1194-1197.
doi: 10.3724/SP.J.1146.2005.01379
Abstract:
A multi-priority delay reservation admission control scheme is proposed. In the scheme, different traffic has different delay threshold so as to provide network QoS. Numerical results show that either the service of high priority traffic or the service of low priority traffic is guaranteed in the new scheme. The utilization of the network is also promoted.
A multi-priority delay reservation admission control scheme is proposed. In the scheme, different traffic has different delay threshold so as to provide network QoS. Numerical results show that either the service of high priority traffic or the service of low priority traffic is guaranteed in the new scheme. The utilization of the network is also promoted.
2007, 29(5): 1198-1201.
doi: 10.3724/SP.J.1146.2006.00484
Abstract:
A novel dynamic scheduling algorithm for mobile streaming media based on the cache window and segment patch pre-fetching is proposed. It employs the scheme that the cache window size can be increased or decreased adaptively according to the popularity of the requested object and the patch bytes that are segmented and cached. The principle is obeyed that the data cached for each mobile streaming media object are in proportion to their popularity at the proxy server. Simulation results show that this strategy is more adaptive than conventional algorithm for the variety of the request arrival rates. It can significantly reduce patching data through patching channel under the circumstance of the same maximum cache space. This can effectively reduce the server load and network bandwidth usage on backbone link. It can faster cache the media object than P3S2A algorithm. It reduces the average occupied cache space at the proxy.
A novel dynamic scheduling algorithm for mobile streaming media based on the cache window and segment patch pre-fetching is proposed. It employs the scheme that the cache window size can be increased or decreased adaptively according to the popularity of the requested object and the patch bytes that are segmented and cached. The principle is obeyed that the data cached for each mobile streaming media object are in proportion to their popularity at the proxy server. Simulation results show that this strategy is more adaptive than conventional algorithm for the variety of the request arrival rates. It can significantly reduce patching data through patching channel under the circumstance of the same maximum cache space. This can effectively reduce the server load and network bandwidth usage on backbone link. It can faster cache the media object than P3S2A algorithm. It reduces the average occupied cache space at the proxy.
2007, 29(5): 1202-1205.
doi: 10.3724/SP.J.1146.2006.01219
Abstract:
To enhance the entire network lifetime of wireless sensor network, this paper puts forward a new transmission mechanism by redundant nodes basing on the characters that the sensor nodes are tiny and energy-limited. The method builds an redundant nodes tree as the transmission agents to realize the information exchange between the clusters and base-station so that the energy consumption of normal nodes and clusters heads can be decreased. The simulation results show that the mechanism can improve the lifetime of effective wireless sensor nodes largely under the condition that the nodes are relative dense and the redundant nodes exist.
To enhance the entire network lifetime of wireless sensor network, this paper puts forward a new transmission mechanism by redundant nodes basing on the characters that the sensor nodes are tiny and energy-limited. The method builds an redundant nodes tree as the transmission agents to realize the information exchange between the clusters and base-station so that the energy consumption of normal nodes and clusters heads can be decreased. The simulation results show that the mechanism can improve the lifetime of effective wireless sensor nodes largely under the condition that the nodes are relative dense and the redundant nodes exist.
2007, 29(5): 1206-1210.
doi: 10.3724/SP.J.1146.2006.00081
Abstract:
Based on the analysis of the communication status in real life Ad hoc networks, a new metric, which utilizes fame, available bandwidth and minimum hops, is presented in order to overcome the node selfishness and drawbacks of min-hop routing selection method. Through cross layer design on MAC and network layer, a novel routing protocol, ARBFAM(Ad hoc Routing Based on Fame, Available Bandwidth and Minimum Hops ), which employs the new metric is given in this paper. Simulation results show, compared with DSR, fairness between nodes is improved and congestion control and load balance is implemented by using ARBFAM. At the same time, average life-span and end-to-end throughput is increased, whereas average end-to-end delay is decreased.
Based on the analysis of the communication status in real life Ad hoc networks, a new metric, which utilizes fame, available bandwidth and minimum hops, is presented in order to overcome the node selfishness and drawbacks of min-hop routing selection method. Through cross layer design on MAC and network layer, a novel routing protocol, ARBFAM(Ad hoc Routing Based on Fame, Available Bandwidth and Minimum Hops ), which employs the new metric is given in this paper. Simulation results show, compared with DSR, fairness between nodes is improved and congestion control and load balance is implemented by using ARBFAM. At the same time, average life-span and end-to-end throughput is increased, whereas average end-to-end delay is decreased.
2007, 29(5): 1211-1214.
doi: 10.3724/SP.J.1146.2005.01351
Abstract:
Group mobility is the typical mobile mode in tactical Ad hoc networks. The characters of groups confine the shaping of zones for Zone Routing Protocol (ZRP) and affect the routing performance greatly. The introduction of location information can improve these. Position Based Modified ZRP (PBMZRP) effectively triggers the neighbor nodes update process of IntrAzone Routing Protocol (IARP) in virtue of node positions, accordingly the broadcast overhead has been decreased much. While, the network diameter restricts the length of routing enquiries during IntErzone Routing Protocol (IERP). Simulation results show that under the circumstance of group mobility, PBMZRP has better performances in the case of delay, throughput, etc.
Group mobility is the typical mobile mode in tactical Ad hoc networks. The characters of groups confine the shaping of zones for Zone Routing Protocol (ZRP) and affect the routing performance greatly. The introduction of location information can improve these. Position Based Modified ZRP (PBMZRP) effectively triggers the neighbor nodes update process of IntrAzone Routing Protocol (IARP) in virtue of node positions, accordingly the broadcast overhead has been decreased much. While, the network diameter restricts the length of routing enquiries during IntErzone Routing Protocol (IERP). Simulation results show that under the circumstance of group mobility, PBMZRP has better performances in the case of delay, throughput, etc.
2007, 29(5): 1215-1219.
doi: 10.3724/SP.J.1146.2005.01685
Abstract:
It is crucial to make Complicated Information System (CIS) secure, interoperable, extensible and controllable. This paper presents a secure CIS architecture model to conduct the construction or reconstruction of CIS. It divides CIS into layers to reduce system complexity. Web service is adopted to fulfill interoperability and extensibility. It uses encryption support layer, security protection and reliability support layer to guarantee system security and stability. It uses system management layer to interact with other layers to make CIS administrable. A case study with performance statistic and network simulation show the model can satisfy the need of e-government without interfere with system performance. This model is apt to security-critical environment such as government, military and bank. Been properly simplified, it can be applied to relative simple information system too.
It is crucial to make Complicated Information System (CIS) secure, interoperable, extensible and controllable. This paper presents a secure CIS architecture model to conduct the construction or reconstruction of CIS. It divides CIS into layers to reduce system complexity. Web service is adopted to fulfill interoperability and extensibility. It uses encryption support layer, security protection and reliability support layer to guarantee system security and stability. It uses system management layer to interact with other layers to make CIS administrable. A case study with performance statistic and network simulation show the model can satisfy the need of e-government without interfere with system performance. This model is apt to security-critical environment such as government, military and bank. Been properly simplified, it can be applied to relative simple information system too.
2007, 29(5): 1220-1223.
doi: 10.3724/SP.J.1146.2005.01281
Abstract:
Aiming at the issue of sensing coverage and connectivity in wireless sensor networks, A complete new algorithm is proposed, on the premise of sensors position aware. The algorithm adopts a clustering method and a decentralized sleeping method to reduce the energy consumption of wireless sensor networks and to prolong the lifetime of wireless sensor networks. The fully connected clustering method ensures that all sensors in a cluster can communicate with each other within one hop. The result of simulation indicates that the algorithm can maintain sensing coverage and connectivity in wireless sensor networks, while the energy consumption of sensor networks is small.
Aiming at the issue of sensing coverage and connectivity in wireless sensor networks, A complete new algorithm is proposed, on the premise of sensors position aware. The algorithm adopts a clustering method and a decentralized sleeping method to reduce the energy consumption of wireless sensor networks and to prolong the lifetime of wireless sensor networks. The fully connected clustering method ensures that all sensors in a cluster can communicate with each other within one hop. The result of simulation indicates that the algorithm can maintain sensing coverage and connectivity in wireless sensor networks, while the energy consumption of sensor networks is small.
2007, 29(5): 1224-1227.
doi: 10.3724/SP.J.1146.2005.01387
Abstract:
The importance of traffic prediction in Wireless Sensor Network (WSN) should not be disregarded. Concerning the ARMA model，a traffic prediction algorithm is proposed based on its own traffic characters. Simulation results show that the presented algorithm can provide high accuracy. Furthermore, using the proposed algorithm to improve the multi-paths route scheme can extend the lifetime of the whole WSN by remaining load evenly distributed among several paths.
The importance of traffic prediction in Wireless Sensor Network (WSN) should not be disregarded. Concerning the ARMA model，a traffic prediction algorithm is proposed based on its own traffic characters. Simulation results show that the presented algorithm can provide high accuracy. Furthermore, using the proposed algorithm to improve the multi-paths route scheme can extend the lifetime of the whole WSN by remaining load evenly distributed among several paths.
2007, 29(5): 1228-1231.
doi: 10.3724/SP.J.1146.2005.01310
Abstract:
The representation and similarity measure of time series are the basis of time series research, which is quite important to improving the efficiency and accuracy of the time series data mining. This paper proposes a shape-based discrete symbolic representation and its corresponding distance measure to measure the similarity between time series. The present method is intuitive and compact, and not sensitive to the shifting, amplitude scaling, compression and stretch of data. The method can reflect the degree of the dynamic change of the tendency and erase the influence of the noises, and it has multi-scale characterization. The experimental results show that the approach has good effect in clustering，which can measure the shape-similarity of time series effectively under various analyzing frequency.
The representation and similarity measure of time series are the basis of time series research, which is quite important to improving the efficiency and accuracy of the time series data mining. This paper proposes a shape-based discrete symbolic representation and its corresponding distance measure to measure the similarity between time series. The present method is intuitive and compact, and not sensitive to the shifting, amplitude scaling, compression and stretch of data. The method can reflect the degree of the dynamic change of the tendency and erase the influence of the noises, and it has multi-scale characterization. The experimental results show that the approach has good effect in clustering，which can measure the shape-similarity of time series effectively under various analyzing frequency.
2007, 29(5): 1232-1235.
doi: 10.3724/SP.J.1146.2005.01122
Abstract:
A fast domain decomposition method is presented for the solution of electromagnetic problems arising in three-dimensions. The original computation domain is meshed and decomposed into several nonoverlapping subdomains by edge-element partitioning technique, which yields a capacitance matrix. Once the unknowns on the interfaces between subdomains have been obtained through the capacitance matrix, the interior unknown fields in each subdomain can be computed with vector finite element method in parallel. Compared with the conventional numerical methods, such as finite element method, method of moments, the present method can greatly reduce the computational complexity and the storage requirement. A preconditioned Krylov subspace method is also developed to accelerate the convergence of the capacitance matrix, and improve the efficiency further. The validity and computational efficiency have been verified by numerical examples.
A fast domain decomposition method is presented for the solution of electromagnetic problems arising in three-dimensions. The original computation domain is meshed and decomposed into several nonoverlapping subdomains by edge-element partitioning technique, which yields a capacitance matrix. Once the unknowns on the interfaces between subdomains have been obtained through the capacitance matrix, the interior unknown fields in each subdomain can be computed with vector finite element method in parallel. Compared with the conventional numerical methods, such as finite element method, method of moments, the present method can greatly reduce the computational complexity and the storage requirement. A preconditioned Krylov subspace method is also developed to accelerate the convergence of the capacitance matrix, and improve the efficiency further. The validity and computational efficiency have been verified by numerical examples.
2007, 29(5): 1236-1239.
doi: 10.3724/SP.J.1146.2005.01375
Abstract:
A modified Particle Swarm Optimization (PSO) algorithm is proposed and used to optimize the sidelobe level of plane arrays, in which special techniques as global best perturbation and jumped inertia weight strategy are adopted. The PSO algorithm is also used to select a better combination of optimal parameters for itself. So that the convergent speed and accuracy of the algorithm are improved. The simulation results of sidelobe reduction of 2-D arrays and pattern synthesis of a sparse array show that it is effective.
A modified Particle Swarm Optimization (PSO) algorithm is proposed and used to optimize the sidelobe level of plane arrays, in which special techniques as global best perturbation and jumped inertia weight strategy are adopted. The PSO algorithm is also used to select a better combination of optimal parameters for itself. So that the convergent speed and accuracy of the algorithm are improved. The simulation results of sidelobe reduction of 2-D arrays and pattern synthesis of a sparse array show that it is effective.
2007, 29(5): 1240-1242.
doi: 10.3724/SP.J.1146.2005.01238
Abstract:
This paper analyzes the influence of difference of amplitude and phase between channels to interferometer receiver, in which calculated results are also given. Based on the essential principle of AGC, the model of eliminating imbalance is established, and the result of simulating proves that the eliminating model is effective. It also can be applicable to other direction-finding systems.
This paper analyzes the influence of difference of amplitude and phase between channels to interferometer receiver, in which calculated results are also given. Based on the essential principle of AGC, the model of eliminating imbalance is established, and the result of simulating proves that the eliminating model is effective. It also can be applicable to other direction-finding systems.
2007, 29(5): 1243-1246.
doi: 10.3724/SP.J.1146.2006.00227
Abstract:
This paper propose a quantitative analysis on the electromagnetic leakage from a shielded-twist-pair with a transverse slot. The mechanism of electromagnetic leakage is analyzed, and then the slotted shielded-twist-pair is regarded as a cascaded network. By applying the hybrid-method, which is the combination of the chain-parameter-equation, the finite-element-method and the subcell-FDTD-method, the electromagnetic leakage from the transverse slot on the shield of the twist-pair are simulated. The results show that, below the frequency of 500MHz, the leaked energy from the slotted shielded-twist-pair is no more than 1% even if the shield layer is cut off.
This paper propose a quantitative analysis on the electromagnetic leakage from a shielded-twist-pair with a transverse slot. The mechanism of electromagnetic leakage is analyzed, and then the slotted shielded-twist-pair is regarded as a cascaded network. By applying the hybrid-method, which is the combination of the chain-parameter-equation, the finite-element-method and the subcell-FDTD-method, the electromagnetic leakage from the transverse slot on the shield of the twist-pair are simulated. The results show that, below the frequency of 500MHz, the leaked energy from the slotted shielded-twist-pair is no more than 1% even if the shield layer is cut off.
2007, 29(5): 1247-1249.
doi: 10.3724/SP.J.1146.2006.00181
Abstract:
This paper presents a Local Osicillator (LO) buffer for WLAN which can tune the I/Q phase of the LO signal in order to calibrate IQ imbalance in direct conversion transceiver. It can tune the phase by means of switching the MOS capacitor array to delay the LO signal. It is implemented in SMIC 0.18m, the layout of 4.8~6GHz I/Q LO buffer occupies a total die area of 650550m2. Post simulation shows that the phase shift of the I or Q LO buffer varies almost linearly from 0 to 8 with the action of 5bit control word, whereas the output power of the LO buffer varies within 0.2 dB.
This paper presents a Local Osicillator (LO) buffer for WLAN which can tune the I/Q phase of the LO signal in order to calibrate IQ imbalance in direct conversion transceiver. It can tune the phase by means of switching the MOS capacitor array to delay the LO signal. It is implemented in SMIC 0.18m, the layout of 4.8~6GHz I/Q LO buffer occupies a total die area of 650550m2. Post simulation shows that the phase shift of the I or Q LO buffer varies almost linearly from 0 to 8 with the action of 5bit control word, whereas the output power of the LO buffer varies within 0.2 dB.
2007, 29(5): 1250-1253.
doi: 10.3724/SP.J.1146.2005.00779
Abstract:
This paper presents an improved power spectrum mathematical expresstion of several injection signals. Fourier series expansion is used to analyze the power spectrum of different injection pulses,such as sine,triangle and rectangle wave. On the basis of it, the effect of injection pulse on semiconductor devices and currents are discussed in this paper. Calculated results show the power spectrum of rectangle wave is larger than others. The mathematical expresstion of power spectrum can be obtained using the method given in this paper. Moreover, it has the advantage of simple calculation compared with other methods.
This paper presents an improved power spectrum mathematical expresstion of several injection signals. Fourier series expansion is used to analyze the power spectrum of different injection pulses,such as sine,triangle and rectangle wave. On the basis of it, the effect of injection pulse on semiconductor devices and currents are discussed in this paper. Calculated results show the power spectrum of rectangle wave is larger than others. The mathematical expresstion of power spectrum can be obtained using the method given in this paper. Moreover, it has the advantage of simple calculation compared with other methods.
2007, 29(5): 1254-1257.
doi: 10.3724/SP.J.1146.2005.01396
Abstract:
For monolithic RF spiral inductor on high-loss silicon substrate, a novel physical model is proposed, in which functions of skin effect, proximity effect and eddy current loss in the substrate to frequency-dependent series parameters Ls and Rs are accounted in the light of modified partial equivalent element circuit methodology and Maxwells electromagnetic theory, and in the meanwhile, the distributed characteristics of parasitic capacitances are captured by n equivalent-circuit. Up to 20GHz, the model reveals quite good accuracy within 7% with data from full-wave electromagnetic filed simulator, including equivalent inductor Leff , resistor Reff and quality factor Q and, hopefully, it can be applied to further theory research and optimum design of RFIC spiral inductor on Si.
For monolithic RF spiral inductor on high-loss silicon substrate, a novel physical model is proposed, in which functions of skin effect, proximity effect and eddy current loss in the substrate to frequency-dependent series parameters Ls and Rs are accounted in the light of modified partial equivalent element circuit methodology and Maxwells electromagnetic theory, and in the meanwhile, the distributed characteristics of parasitic capacitances are captured by n equivalent-circuit. Up to 20GHz, the model reveals quite good accuracy within 7% with data from full-wave electromagnetic filed simulator, including equivalent inductor Leff , resistor Reff and quality factor Q and, hopefully, it can be applied to further theory research and optimum design of RFIC spiral inductor on Si.
2007, 29(5): 1263-1266.
doi: 10.3724/SP.J.1146.2006.01300
Abstract:
First of all, the in-loaded and out-loaded technologies of resonant cavity being used in the multi-beam klystron and some associated microwave attenuating materials are analyzed and compared. Not only the ways of adjustment of out-loaded resonant cavity quality characteristic is illuminated in theory, but is designed the out-loaded resonant cavity meeting the demand. Finally, the asymmetry of the E-field of the mode caused by the out-loaded cavity is adjusted and the influent factors and the change laws of quality characteristic of the out-loaded resonant cavity are located.
First of all, the in-loaded and out-loaded technologies of resonant cavity being used in the multi-beam klystron and some associated microwave attenuating materials are analyzed and compared. Not only the ways of adjustment of out-loaded resonant cavity quality characteristic is illuminated in theory, but is designed the out-loaded resonant cavity meeting the demand. Finally, the asymmetry of the E-field of the mode caused by the out-loaded cavity is adjusted and the influent factors and the change laws of quality characteristic of the out-loaded resonant cavity are located.
2007, 29(5): 1267-1270.
doi: 10.3724/SP.J.1146.2005.01447
Abstract:
A new method for simulation line realization based on Back Propagation Neural Network (BP NN) is presented in the paper. Applying Genetic Algorithm (GA) to optimize the neural networks structure, BP NN is trained to correspond the transfer function of simulation line. Activation function of NN is approximated with STAM (Symmetric Table and Addition Method) algorithms. A coaxial-cable which is 10000m long and 55 line characteristic impedance is simulated and realized by using FPGA and D/A converter. Experimental results show that the proposed approach can greatly reduce the memory of hardware realization. This method can be generalized to simulate the transmission network with unknown transfer function.
A new method for simulation line realization based on Back Propagation Neural Network (BP NN) is presented in the paper. Applying Genetic Algorithm (GA) to optimize the neural networks structure, BP NN is trained to correspond the transfer function of simulation line. Activation function of NN is approximated with STAM (Symmetric Table and Addition Method) algorithms. A coaxial-cable which is 10000m long and 55 line characteristic impedance is simulated and realized by using FPGA and D/A converter. Experimental results show that the proposed approach can greatly reduce the memory of hardware realization. This method can be generalized to simulate the transmission network with unknown transfer function.
2007, 29(5): 1258-1262.
doi: 10.3724/SP.J.1146.2006.00886
Abstract:
In this paper, the basic factors of the techniques combining the polarimetric synthetic aperture radar (SAR) with interferometric SAR are considered firstly, and then the basic concepts of coherence optimization and target decomposition of polarimetric SAR interferometry are illustrated. The current status of polarimetric SAR interferometry technique, the developments of typical spaceborne polarimetric SAR systems and the applications of polarimetric SAR interferometry are summarized.
In this paper, the basic factors of the techniques combining the polarimetric synthetic aperture radar (SAR) with interferometric SAR are considered firstly, and then the basic concepts of coherence optimization and target decomposition of polarimetric SAR interferometry are illustrated. The current status of polarimetric SAR interferometry technique, the developments of typical spaceborne polarimetric SAR systems and the applications of polarimetric SAR interferometry are summarized.
