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2010 Vol. 32, No. 6
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2010, 32(6): 1271-1276.
doi: 10.3724/SP.J.1146.2009.00853
Abstract:
An Enhanced Multiple Model Particle Filter(EMMPF) algorithm is presented for maneuvering target tracking. Rather than allocating the particles to the various modes according to mode probabilities as the MMPF, the new algorithm proposes an approach which enables the user to control the number of particles in a certain mode flexibly without interaction between particles of different mode. The estimations of mode and state are calculated respectively, and the posterior probability of each model is updated with the model likelihood function. It is demonstrated that the new algorithm can achieve better performance with less particles, compared with MMPF.
An Enhanced Multiple Model Particle Filter(EMMPF) algorithm is presented for maneuvering target tracking. Rather than allocating the particles to the various modes according to mode probabilities as the MMPF, the new algorithm proposes an approach which enables the user to control the number of particles in a certain mode flexibly without interaction between particles of different mode. The estimations of mode and state are calculated respectively, and the posterior probability of each model is updated with the model likelihood function. It is demonstrated that the new algorithm can achieve better performance with less particles, compared with MMPF.
2010, 32(6): 1277-1283.
doi: 10.3724/SP.J.1146.2009.00857
Abstract:
A new data exponent weighted fuzzy clustering approach is proposed by introducing a set of exponent weighting factors and influence exponent, the new approach makes it possible to treat the data points discriminatively. The new approach is combined with the existing Gustafson-Kessel (G-K) algorithm and a new algorithm, DWG-K is presented. Numerical experiments show that the DWG-K is better than G-K in improving the quality of clustering, and in the outliers mining, DWG-K detects the outliers with the global view and the physical meaning of outliers is clearer, and moreover, the computational efficiency is significantly higher than the current widely used density-based method.
A new data exponent weighted fuzzy clustering approach is proposed by introducing a set of exponent weighting factors and influence exponent, the new approach makes it possible to treat the data points discriminatively. The new approach is combined with the existing Gustafson-Kessel (G-K) algorithm and a new algorithm, DWG-K is presented. Numerical experiments show that the DWG-K is better than G-K in improving the quality of clustering, and in the outliers mining, DWG-K detects the outliers with the global view and the physical meaning of outliers is clearer, and moreover, the computational efficiency is significantly higher than the current widely used density-based method.
2010, 32(6): 1284-1288.
doi: 10.3724/SP.J.1146.2009.00861
Abstract:
One-Class Support Vector Machines (OCSVMs) distinguish outliers by computing a hyper-plane in feature space. The choice of the origin as separation point is arbitrary, which affects the decision boundary, and the distribution of samples has impact on the performance. Expanding the algorithm into solving two-class classification problems overcomes the drawbacks to a certain degree. However, the class imbalance problem is serious and the labeled outliers are rare or even non-existing. In this paper, a new Outlier OCSVM is proposed and a framework is designed for unsupervised outlier detection. Respectively scored by distance from hyper-plane and probabilistic output value, two definitions of outlier degree are presented. After picking out some suspicious outliers via combining the two criterions of outlier degree, the adjusted Outlier OCSVM starts the training operations, two parts of the dataset are updated interactively through comparison of the outputs. Experiment results on benchmark datasets show that the method can effectively improve the detection rate and reduce false positive rate, easy and reliable.
One-Class Support Vector Machines (OCSVMs) distinguish outliers by computing a hyper-plane in feature space. The choice of the origin as separation point is arbitrary, which affects the decision boundary, and the distribution of samples has impact on the performance. Expanding the algorithm into solving two-class classification problems overcomes the drawbacks to a certain degree. However, the class imbalance problem is serious and the labeled outliers are rare or even non-existing. In this paper, a new Outlier OCSVM is proposed and a framework is designed for unsupervised outlier detection. Respectively scored by distance from hyper-plane and probabilistic output value, two definitions of outlier degree are presented. After picking out some suspicious outliers via combining the two criterions of outlier degree, the adjusted Outlier OCSVM starts the training operations, two parts of the dataset are updated interactively through comparison of the outputs. Experiment results on benchmark datasets show that the method can effectively improve the detection rate and reduce false positive rate, easy and reliable.
2010, 32(6): 1289-1294.
doi: 10.3724/SP.J.1146.2008.01387
Abstract:
Multi-target tracking is becoming one of most focusing research topics because of the modern military affair requirements as well as civil developments. Among all the techniques, Probability Hypothesis Density(PHD) filtering approach, especially Gaussian Mixture PHD(GMPHD) filter, which has a closed form recursion, has shown its advantages in tracking unknown number of targets despite the impact of noise and missing detection etc. Existing PHD trajectory tracking methods combining PHD filter, which can not estimate the trajectories of multi-target alone, with traditional data association, are computationally expensive and almost intractable. In this paper, a brand new multi-target trajectory tracking algorithm based on random finite set theory is brought forward by adopting classical signal detection technique along with GMPHD filter. Using hypotheses representing the trajectory information, data association is accomplished through the hypothesis matrix judging on the same basement as track managing function. The simulation results suggest that this algorithm not only significantly alleviates the heavy computing load, but also performs multi-target trajectory tracking effectively in the meantime.
Multi-target tracking is becoming one of most focusing research topics because of the modern military affair requirements as well as civil developments. Among all the techniques, Probability Hypothesis Density(PHD) filtering approach, especially Gaussian Mixture PHD(GMPHD) filter, which has a closed form recursion, has shown its advantages in tracking unknown number of targets despite the impact of noise and missing detection etc. Existing PHD trajectory tracking methods combining PHD filter, which can not estimate the trajectories of multi-target alone, with traditional data association, are computationally expensive and almost intractable. In this paper, a brand new multi-target trajectory tracking algorithm based on random finite set theory is brought forward by adopting classical signal detection technique along with GMPHD filter. Using hypotheses representing the trajectory information, data association is accomplished through the hypothesis matrix judging on the same basement as track managing function. The simulation results suggest that this algorithm not only significantly alleviates the heavy computing load, but also performs multi-target trajectory tracking effectively in the meantime.
2010, 32(6): 1295-1300.
doi: 10.3724/SP.J.1146.2009.01083
Abstract:
For lower detection probability problem of small IR targets in a complex non-homogeneous background, an improved M-estimation filtering algorithm based on residual is proposed to suppress background clutters. The algorithm introduces the basic model of M-estimation to predict background, and target pixels and observed noise are considered as the mixed interference of background estimation. It puts forward the correction function c() related to residual to adaptively adjust gain to reduce the abnormal samples influence of background estimation and increases the accuracy of estimation. Meanwhile, the proposed algorithm uses the forget factor to entreat the non-homogeneous background prediction and the robustness is improved. Experimental results on IR images illustrate that the proposed algorithm can not only predict background effectively in non-homogeneous background but preserve targets information to maximum extent. As a result, the proposed algorithm has higher detection probability.
For lower detection probability problem of small IR targets in a complex non-homogeneous background, an improved M-estimation filtering algorithm based on residual is proposed to suppress background clutters. The algorithm introduces the basic model of M-estimation to predict background, and target pixels and observed noise are considered as the mixed interference of background estimation. It puts forward the correction function c() related to residual to adaptively adjust gain to reduce the abnormal samples influence of background estimation and increases the accuracy of estimation. Meanwhile, the proposed algorithm uses the forget factor to entreat the non-homogeneous background prediction and the robustness is improved. Experimental results on IR images illustrate that the proposed algorithm can not only predict background effectively in non-homogeneous background but preserve targets information to maximum extent. As a result, the proposed algorithm has higher detection probability.
2010, 32(6): 1301-1305.
doi: 10.3724/SP.J.1146.2009.00792
Abstract:
There are some problems in GM(1,1) model, such as, model method biased, compatibility condition not satisfied, transformation inconsistent and first number of the initial sequence not functioning high precision prediction in model after an accumulated generating operation. This paper deals with the GM(1,1) model improvement in reconstructing the GM(1,1) white background value, using white Background value weighted average of forward (backword) difference quotient as the new optimized models grey derivative, regarding the value of x(1)(n) replacement of x(0)(1) as the models initial condition. The new model improves the accuracy of the precision greatly. Even if the development coefficient is bigger than 2, the fitting precision of the new model is still high. The analysis of some examples indicates that the new optimized method using whether in low growth index series or in high growth index series has a very high practicability and reliability.
There are some problems in GM(1,1) model, such as, model method biased, compatibility condition not satisfied, transformation inconsistent and first number of the initial sequence not functioning high precision prediction in model after an accumulated generating operation. This paper deals with the GM(1,1) model improvement in reconstructing the GM(1,1) white background value, using white Background value weighted average of forward (backword) difference quotient as the new optimized models grey derivative, regarding the value of x(1)(n) replacement of x(0)(1) as the models initial condition. The new model improves the accuracy of the precision greatly. Even if the development coefficient is bigger than 2, the fitting precision of the new model is still high. The analysis of some examples indicates that the new optimized method using whether in low growth index series or in high growth index series has a very high practicability and reliability.
LLE-Based Classification Algorithm and Its Application to Passive Millimeter Wave Target Recognition
2010, 32(6): 1306-1310.
doi: 10.3724/SP.J.1146.2009.00877
Abstract:
A new one-class classification algorithm is put forward based on the idea of Locally Linear Embedding (LLE) and the low dimensional manifold of data distribution, for the issue of one-class classification of pattern recognition. The low dimensional manifold the short-time Fourier spectrum of passive millimeter wave (MMW) detector echo signal is found, which characteristics are explored as well. The algorithm is more efficient than present popular one-class classification algorithm when applied to passive MMW metal target recognition. Moreover, it is not sensitive to input parameters and is robust to data aliasing.
A new one-class classification algorithm is put forward based on the idea of Locally Linear Embedding (LLE) and the low dimensional manifold of data distribution, for the issue of one-class classification of pattern recognition. The low dimensional manifold the short-time Fourier spectrum of passive millimeter wave (MMW) detector echo signal is found, which characteristics are explored as well. The algorithm is more efficient than present popular one-class classification algorithm when applied to passive MMW metal target recognition. Moreover, it is not sensitive to input parameters and is robust to data aliasing.
2010, 32(6): 1311-1315.
doi: 10.3724/SP.J.1146.2008.01111
Abstract:
The algorithms of Graph Embedding model the manifold of data set by an undirected weighted graph. Some manifold learning algorithms can be unified by this framework according to the respective weighted matrix. For the small sample size problem, Linearization of Graph Embedding (LGE) needs to project the data to the PCA subspace. In this paper, a Direct LGE (DLGE) algorithm is proposed which can directly extract features from the data set. Moreover, DLGE employs the least-squares orthogonalization for the preserving feature vectors. The simulation results on several face databases show that DLGE has better ability for face representation, and also demonstrate the effectiveness and robustness of our proposed algorithm.
The algorithms of Graph Embedding model the manifold of data set by an undirected weighted graph. Some manifold learning algorithms can be unified by this framework according to the respective weighted matrix. For the small sample size problem, Linearization of Graph Embedding (LGE) needs to project the data to the PCA subspace. In this paper, a Direct LGE (DLGE) algorithm is proposed which can directly extract features from the data set. Moreover, DLGE employs the least-squares orthogonalization for the preserving feature vectors. The simulation results on several face databases show that DLGE has better ability for face representation, and also demonstrate the effectiveness and robustness of our proposed algorithm.
2010, 32(6): 1316-1320.
doi: 10.3724/SP.J.1146.2009.00867
Abstract:
Image quality assessment is fundamental importance for image or video processing system. Following the knowledge of properties of human visual system and features of natural image, a novel full reference image quality assessment based on the regular directional distortion is proposed in this paper. The proposed method is low complexity and has clear physical structure. The experimental results upon image database show that the proposed method is in accordance with characteristic of human visual system and has a good consistency with the subjective assessment of human beings.
Image quality assessment is fundamental importance for image or video processing system. Following the knowledge of properties of human visual system and features of natural image, a novel full reference image quality assessment based on the regular directional distortion is proposed in this paper. The proposed method is low complexity and has clear physical structure. The experimental results upon image database show that the proposed method is in accordance with characteristic of human visual system and has a good consistency with the subjective assessment of human beings.
2010, 32(6): 1321-1326.
doi: 10.3724/SP.J.1146.2009.00868
Abstract:
At present, the effective way to resolve the contradiction between huge space-borne SAR raw data rate and limited on-board data-transmission bandwidth is space-borne SAR raw data compression. The higher compression ratio is, the lower data rate will be, but larger quantization error will affect the velocity measurement accuracy of SAR-GMTI. The lower compression ratio is, the less effect of data compression on velocity measurement accuracy is, but the higher data rate will be. Therefore, the choice of data compression ratio needs achieve a compromise between data rate and velocity measurement accuracy. This paper establishes the echo simulation model of space-borne SAR/GMTI system and simulates the raw data of space-borne SAR-GMTI. For Displaced Phase Center Antenna (DPCA) and Along-Track Interferometry (ATI) methods which have significant application potentialities in practice, this paper analyzes the effect of Block Adaptive Quantization (BAQ) algorithm on velocity measurement accuracy in detail. The results of this paper provides important theory basis for the choice of compression ratio of the space-borne SAR/GMTI system.
At present, the effective way to resolve the contradiction between huge space-borne SAR raw data rate and limited on-board data-transmission bandwidth is space-borne SAR raw data compression. The higher compression ratio is, the lower data rate will be, but larger quantization error will affect the velocity measurement accuracy of SAR-GMTI. The lower compression ratio is, the less effect of data compression on velocity measurement accuracy is, but the higher data rate will be. Therefore, the choice of data compression ratio needs achieve a compromise between data rate and velocity measurement accuracy. This paper establishes the echo simulation model of space-borne SAR/GMTI system and simulates the raw data of space-borne SAR-GMTI. For Displaced Phase Center Antenna (DPCA) and Along-Track Interferometry (ATI) methods which have significant application potentialities in practice, this paper analyzes the effect of Block Adaptive Quantization (BAQ) algorithm on velocity measurement accuracy in detail. The results of this paper provides important theory basis for the choice of compression ratio of the space-borne SAR/GMTI system.
2010, 32(6): 1327-1331.
doi: 10.3724/SP.J.1146.2009.00832
Abstract:
GLRT is an efficient method to resolve the detection issue of range spread targets in compound Gaussian clutter. But normal GLRT will be out of action when the velocity of target is unknown. Farther research is performed under this situation. An estimation algorithm of Doppler frequency based on general eigenvalue decomposition is proposed, which can estimate Doppler frequency effectively. And a Robust GLRT (R-GLRT) detector is designed. The results of simulation show the effectiveness of this detector.
GLRT is an efficient method to resolve the detection issue of range spread targets in compound Gaussian clutter. But normal GLRT will be out of action when the velocity of target is unknown. Farther research is performed under this situation. An estimation algorithm of Doppler frequency based on general eigenvalue decomposition is proposed, which can estimate Doppler frequency effectively. And a Robust GLRT (R-GLRT) detector is designed. The results of simulation show the effectiveness of this detector.
2010, 32(6): 1332-1337.
doi: 10.3724/SP.J.1146.2009.01104
Abstract:
Space Time Adaptive Processing (STAP) shows notable performance degradation when secondary data is contaminated by target-like signals or only a small number of secondary data is available. To solve the problem, a new methodology exploring characteristic structure of clutter ridge is proposed to suppress clutter which obscure objects. The phase spectra of ground clutter seen by an airborne radar are taken account of and a covariance matrix is obtained incorporating two-dimension Gaussian power spectral density model. The parameter of the model can be obtained by exploring the sensed environment. Simulation based on simulated data and MCARM real data show that noticeable performance improvements can be obtained with the new approach in heterogeneous environments.
Space Time Adaptive Processing (STAP) shows notable performance degradation when secondary data is contaminated by target-like signals or only a small number of secondary data is available. To solve the problem, a new methodology exploring characteristic structure of clutter ridge is proposed to suppress clutter which obscure objects. The phase spectra of ground clutter seen by an airborne radar are taken account of and a covariance matrix is obtained incorporating two-dimension Gaussian power spectral density model. The parameter of the model can be obtained by exploring the sensed environment. Simulation based on simulated data and MCARM real data show that noticeable performance improvements can be obtained with the new approach in heterogeneous environments.
2010, 32(6): 1338-1342.
doi: 10.3724/SP.J.1146.2008.01637
Abstract:
Phase synchronization is a key issue in bistatic and multistatic Synthetic Aperture Radar (SAR) imaging. This paper discusses this issue based on experiment data, presents a multi-PRF link synchronization scheme, which solves frequency measurement ambiguities by using of Chinese remainder theorem and accurately estimates random phase by duplex multi-channel link with low synchronization frequency. The performance of presented scheme is analyzed in theory and demonstrated with simulations.
Phase synchronization is a key issue in bistatic and multistatic Synthetic Aperture Radar (SAR) imaging. This paper discusses this issue based on experiment data, presents a multi-PRF link synchronization scheme, which solves frequency measurement ambiguities by using of Chinese remainder theorem and accurately estimates random phase by duplex multi-channel link with low synchronization frequency. The performance of presented scheme is analyzed in theory and demonstrated with simulations.
2010, 32(6): 1343-1349.
doi: 10.3724/SP.J.1146.2009.00860
Abstract:
In the paper, making use of two key techniques in SAR domainmutichannel SAR and PolSAR, a method to suppress both the blanketing jamming and the deceptive jamming is provided in Dual-channel PolSAR (D-PolSAR) system. First, the model of the D-PolSAR system is established, and the signal and jamming in the D-PolSAR system are analyzed; then by comparing the difference between jamming and real signal, a Two-Channel-Cancellation(TCC) method based on phase compensation is proposed to suppress these two types of jamming. The simulation results validate the effectiveness of proposed method.
In the paper, making use of two key techniques in SAR domainmutichannel SAR and PolSAR, a method to suppress both the blanketing jamming and the deceptive jamming is provided in Dual-channel PolSAR (D-PolSAR) system. First, the model of the D-PolSAR system is established, and the signal and jamming in the D-PolSAR system are analyzed; then by comparing the difference between jamming and real signal, a Two-Channel-Cancellation(TCC) method based on phase compensation is proposed to suppress these two types of jamming. The simulation results validate the effectiveness of proposed method.
2010, 32(6): 1350-1354.
doi: 10.3724/SP.J.1146.2009.00839
Abstract:
It is difficult for the traditional radar to detect effectively the high speed moving target with the long time coherent integration method. In this paper, Multi-Input Multi-Output (MIMO) noise radar, in which the parallel coherent processing of the multi-channel echo data in a short time is exploited to replace the long time coherent integrative detection, is used for high speed moving target detection. Thus the detection performance of MIMO noise radar may not be affected by the range migration, the radial velocity variety and the fast Radar Cross-Section (RCS) fluctuation. Then the multiple high speed moving targets can be effectively detected without range ambiguities with MIMO noise radar. Simulations verify the superiority of MIMO noise radar on high speed moving target detection.
It is difficult for the traditional radar to detect effectively the high speed moving target with the long time coherent integration method. In this paper, Multi-Input Multi-Output (MIMO) noise radar, in which the parallel coherent processing of the multi-channel echo data in a short time is exploited to replace the long time coherent integrative detection, is used for high speed moving target detection. Thus the detection performance of MIMO noise radar may not be affected by the range migration, the radial velocity variety and the fast Radar Cross-Section (RCS) fluctuation. Then the multiple high speed moving targets can be effectively detected without range ambiguities with MIMO noise radar. Simulations verify the superiority of MIMO noise radar on high speed moving target detection.
2010, 32(6): 1355-1360.
doi: 10.3724/SP.J.1146.2009.00899
Abstract:
The micro-Doppler signals of humans heartbeat, breathe and arm-moving using through-wall radar are nonlinear and non-stationary, which can be analyzed by Empirical Mode Decomposition (EMD). Due to the mode mixing problem in EMD, an improved Ensemble Empirical Mode Decomposition (EEMD) is proposed in this paper, and is applied to the human micro-Doppler character analysis of the through-wall radar. The time-frequency-energy spectrum is obtained by using Hilbert-Huang Transform (HHT) to every Intrinsic Mode Functions (IMF). The analysis on simulation data and experimental results show that the improved EEMD can effectively eliminate the mode mixing problem in EMD, which means different frequency scales in humans micro-Doppler signals are decomposed in different IMF. Furthermore, this method can restrain the noise in the original signal and more detail information can be seen clearly in the time-frequency spectrum.
The micro-Doppler signals of humans heartbeat, breathe and arm-moving using through-wall radar are nonlinear and non-stationary, which can be analyzed by Empirical Mode Decomposition (EMD). Due to the mode mixing problem in EMD, an improved Ensemble Empirical Mode Decomposition (EEMD) is proposed in this paper, and is applied to the human micro-Doppler character analysis of the through-wall radar. The time-frequency-energy spectrum is obtained by using Hilbert-Huang Transform (HHT) to every Intrinsic Mode Functions (IMF). The analysis on simulation data and experimental results show that the improved EEMD can effectively eliminate the mode mixing problem in EMD, which means different frequency scales in humans micro-Doppler signals are decomposed in different IMF. Furthermore, this method can restrain the noise in the original signal and more detail information can be seen clearly in the time-frequency spectrum.
2010, 32(6): 1361-1365.
doi: 10.3724/SP.J.1146.2009.00734
Abstract:
In this paper, an innovative airborne forward-looking SAR system using antenna array is studied, and a new three-dimensional imaging algorithm is proposed for airborne forward-looking SAR based on the image geometry and the characteristic of echo signal. A single SAR image was obtained with chirp scaling algorithm until all the receiving antennas have received echoes once. When plane flies along the track continuously, a sequence of two-dimensional SAR images in front of the flight path can be obtained. Then the three-dimensional image of forward-looking SAR can be obtained by focusing one section at an azimuth position one time with Range-Doppler algorithm until all the sections have been processed. Raw data of forward-looking SAR in X-band is simulated and three-dimensional image is achieved. The imaging result is analyzed, and simulation results confirm the validity of the proposed algorithm.
In this paper, an innovative airborne forward-looking SAR system using antenna array is studied, and a new three-dimensional imaging algorithm is proposed for airborne forward-looking SAR based on the image geometry and the characteristic of echo signal. A single SAR image was obtained with chirp scaling algorithm until all the receiving antennas have received echoes once. When plane flies along the track continuously, a sequence of two-dimensional SAR images in front of the flight path can be obtained. Then the three-dimensional image of forward-looking SAR can be obtained by focusing one section at an azimuth position one time with Range-Doppler algorithm until all the sections have been processed. Raw data of forward-looking SAR in X-band is simulated and three-dimensional image is achieved. The imaging result is analyzed, and simulation results confirm the validity of the proposed algorithm.
2010, 32(6): 1366-1369.
doi: 10.3724/SP.J.1146.2009.00784
Abstract:
The main difficulty in the use of pseudolites is the near-far effect, where the strong signal component prevents a conventional receiver from detecting the weak component. A new solution based on the orthogonality of the pseudolite signal is presented, which constructs the orthogonal projection of the strong component and then cancels out this projection from the received signal to reduce the interference of the strong component on acquiring the weaker. This solution needs neither to modify the receivers hardware nor to estimate the amplitude of the signal component. Simulation results shows that, at the same acquisition probability of 90%, the performance of near-far resistance of this new method compared with conventional sliding detector is improved about 9 dB.
The main difficulty in the use of pseudolites is the near-far effect, where the strong signal component prevents a conventional receiver from detecting the weak component. A new solution based on the orthogonality of the pseudolite signal is presented, which constructs the orthogonal projection of the strong component and then cancels out this projection from the received signal to reduce the interference of the strong component on acquiring the weaker. This solution needs neither to modify the receivers hardware nor to estimate the amplitude of the signal component. Simulation results shows that, at the same acquisition probability of 90%, the performance of near-far resistance of this new method compared with conventional sliding detector is improved about 9 dB.
2010, 32(6): 1370-1376.
doi: 10.3724/SP.J.1146.2009.00227
Abstract:
Considering the mechanism of two-channel direction-finding systems with four-arm spiral antenna, guidance signal generation model related to the superposed field radiated by the antennae of radar and decoy is presented. A simple and practical movement model of Anti-Radiation Missile(ARM) is introduced. The dynamic simulation methods and formulae for analyzing deception effect are proposed. The simulation results show that high survival probability of the radar and the decoy can be achieved if the decoy level is set to some appropriate values when the distance between the radar and the decoy is set to 250-300 m, and the initial phase of the decoy radiation field has relatively less effect on the survival probability.
Considering the mechanism of two-channel direction-finding systems with four-arm spiral antenna, guidance signal generation model related to the superposed field radiated by the antennae of radar and decoy is presented. A simple and practical movement model of Anti-Radiation Missile(ARM) is introduced. The dynamic simulation methods and formulae for analyzing deception effect are proposed. The simulation results show that high survival probability of the radar and the decoy can be achieved if the decoy level is set to some appropriate values when the distance between the radar and the decoy is set to 250-300 m, and the initial phase of the decoy radiation field has relatively less effect on the survival probability.
2010, 32(6): 1377-1383.
doi: 10.3724/SP.J.1146.2009.01437
Abstract:
For changing the status that optimization and design of frequency reconfigurable microstrip antenna recently is usually depended on repeated experiments, an efficient and fast method is proposed in this paper. A Novel Quantum Genetic Algorithm (NQGA) is combined with universal spatial MoM in the proposed method and calculating time is saved by using Direct Matrix Manipulation (DMM) technique used in computing Z-matrix. Using this method, a frequency reconfigurable cylindrical conformal microstrip antenna is obtained that can work at ten or more narrow frequency-bands. Comparing the optimization results in the paper with commercial software results shows that the method in this paper is correct and efficient.
For changing the status that optimization and design of frequency reconfigurable microstrip antenna recently is usually depended on repeated experiments, an efficient and fast method is proposed in this paper. A Novel Quantum Genetic Algorithm (NQGA) is combined with universal spatial MoM in the proposed method and calculating time is saved by using Direct Matrix Manipulation (DMM) technique used in computing Z-matrix. Using this method, a frequency reconfigurable cylindrical conformal microstrip antenna is obtained that can work at ten or more narrow frequency-bands. Comparing the optimization results in the paper with commercial software results shows that the method in this paper is correct and efficient.
2010, 32(6): 1384-1388.
doi: 10.3724/SP.J.1146.2009.00881
Abstract:
In this paper, the numerical properties of higher-order Locally One Dimensionally Finite-Difference Time-Domain (LOD-FDTD) are investigated, i.e. stability, numerical dispersion, and convergence. The universal formulas of the amplitude factor and the numerical dispersion relationship are derived for 3D varying-order LOD-FDTD, and their unconditional stability is analytically proved. Based on this universal formula, the numerical convergence of this class of methods is discussed, and the convergence condition is presented for the first time. Numerical results in calculating the resonant frequency show that, higher-order methods can achieve better performance while not dramatically increasing computational time.
In this paper, the numerical properties of higher-order Locally One Dimensionally Finite-Difference Time-Domain (LOD-FDTD) are investigated, i.e. stability, numerical dispersion, and convergence. The universal formulas of the amplitude factor and the numerical dispersion relationship are derived for 3D varying-order LOD-FDTD, and their unconditional stability is analytically proved. Based on this universal formula, the numerical convergence of this class of methods is discussed, and the convergence condition is presented for the first time. Numerical results in calculating the resonant frequency show that, higher-order methods can achieve better performance while not dramatically increasing computational time.
2010, 32(6): 1389-1394.
doi: 10.3724/SP.J.1146.2009.00873
Abstract:
To solve the problem of an excessive area required to implement milliseconds reset time with resistance and capacitance in POR (Power-On Reset) circuit, an area-efficiency delay circuit based on an exponential time-extending technique is proposed in this paper. The circuit utilizes asynchronous frequency division to increase delay exponentially, using the period of signal which ring oscillator generates as a reference delay unit and is capable of implementing milliseconds delay for minimum silicon area. It is used to generate a long enough reset time in the POR circuit. To verify the technique, the circuit is designed and fabricated in the SMIC 0.18 m process. According to the measured results, the circuit typically achieves 0.91 ms delay with an area of 172 m75 m and 54.9 ms delay with an area of 172 m95 m. As compared with RC method, the circuit can respectively save at least 82.8% and 97% layout area for implementing the same delays.
To solve the problem of an excessive area required to implement milliseconds reset time with resistance and capacitance in POR (Power-On Reset) circuit, an area-efficiency delay circuit based on an exponential time-extending technique is proposed in this paper. The circuit utilizes asynchronous frequency division to increase delay exponentially, using the period of signal which ring oscillator generates as a reference delay unit and is capable of implementing milliseconds delay for minimum silicon area. It is used to generate a long enough reset time in the POR circuit. To verify the technique, the circuit is designed and fabricated in the SMIC 0.18 m process. According to the measured results, the circuit typically achieves 0.91 ms delay with an area of 172 m75 m and 54.9 ms delay with an area of 172 m95 m. As compared with RC method, the circuit can respectively save at least 82.8% and 97% layout area for implementing the same delays.
2010, 32(6): 1395-1400.
doi: 10.3724/SP.J.1146.2008.01689
Abstract:
A novel FPGA simulated annealing placement algorithm is proposed to improve the routability and optimize the length of wires. Different cost functions are applied to different temperature range. In high temperature stage, the half perimeter method is utilized to fast optimize the placement; while in low temperature stage, a variable factor is added into the cost function and the reasonable temper process is also used to improve the quality of placement. Experiment results demonstrate that, compared with the VPR, the proposed method requires 6% fewer routing tracks and the length of wire is 4~23% shorter.
A novel FPGA simulated annealing placement algorithm is proposed to improve the routability and optimize the length of wires. Different cost functions are applied to different temperature range. In high temperature stage, the half perimeter method is utilized to fast optimize the placement; while in low temperature stage, a variable factor is added into the cost function and the reasonable temper process is also used to improve the quality of placement. Experiment results demonstrate that, compared with the VPR, the proposed method requires 6% fewer routing tracks and the length of wire is 4~23% shorter.
2010, 32(6): 1401-1405.
doi: 10.3724/SP.J.1146.2009.00768
Abstract:
A new parasitic-mode-suppressing method for TM310 mode (operating mode) cylindrical resonator is presented in this paper. In order to suppress TM020 mode, a receiving-antenna is set into the resonator, and then the expression for frequency offset is derived based on the electromagnetic theory. Furthermore, two conclusions can be obtained from the formula: frequency offset of a mode only depends on the modes electric field in the position of the receiving-antenna; setting the antenna suitably can make frequency offsets of TM310 mode and TM020 mode differently, so the frequency interval between TM310 mode and TM020 mode may be enlarged, which helps avoid the interference of TM020 mode in the TM310 mode resonator. On the other hand, short-circuit- pole-array set into the resonator is used to suppress the TM+310 mode. By means of CST-MWS, this kind of resonator in X-band is simulated, which shows the availability of the parasitic-mode-suppressing method.
A new parasitic-mode-suppressing method for TM310 mode (operating mode) cylindrical resonator is presented in this paper. In order to suppress TM020 mode, a receiving-antenna is set into the resonator, and then the expression for frequency offset is derived based on the electromagnetic theory. Furthermore, two conclusions can be obtained from the formula: frequency offset of a mode only depends on the modes electric field in the position of the receiving-antenna; setting the antenna suitably can make frequency offsets of TM310 mode and TM020 mode differently, so the frequency interval between TM310 mode and TM020 mode may be enlarged, which helps avoid the interference of TM020 mode in the TM310 mode resonator. On the other hand, short-circuit- pole-array set into the resonator is used to suppress the TM+310 mode. By means of CST-MWS, this kind of resonator in X-band is simulated, which shows the availability of the parasitic-mode-suppressing method.
2010, 32(6): 1406-1411.
doi: 10.3724/SP.J.1146.2009.00891
Abstract:
Spectrum sensing is a key functional part for cognitive radio networks. In heterogeneous networks, the mobility of cognitive nodes will lead to changes in the received signal strength and noise power, which make it difficult for cognitive users to achieve optimal sensing performance at all times using traditional spectrum sensing methods with fixed thresholds. To solve this problem, an adaptive threshold scheme is proposed in this paper. The Steepest Descent Algorithm (SDA) is used to adjust thresholds of all cooperative nodes and the optimal data fusion rule is adopted in the control center to decrease the average Bayesian risk. No prior information of primary signals, channel fading and noise power is needed and the optimal sensing performance is achieved by applying the proposed scheme. Simulation results confirm that the proposed method can quickly converge to optimal sensing parameters in spatial temporal varying environment.
Spectrum sensing is a key functional part for cognitive radio networks. In heterogeneous networks, the mobility of cognitive nodes will lead to changes in the received signal strength and noise power, which make it difficult for cognitive users to achieve optimal sensing performance at all times using traditional spectrum sensing methods with fixed thresholds. To solve this problem, an adaptive threshold scheme is proposed in this paper. The Steepest Descent Algorithm (SDA) is used to adjust thresholds of all cooperative nodes and the optimal data fusion rule is adopted in the control center to decrease the average Bayesian risk. No prior information of primary signals, channel fading and noise power is needed and the optimal sensing performance is achieved by applying the proposed scheme. Simulation results confirm that the proposed method can quickly converge to optimal sensing parameters in spatial temporal varying environment.
2010, 32(6): 1412-1417.
doi: 10.3724/SP.J.1146.2009.00906
Abstract:
Several frequency-domain channel estimation algorithms based on a new pilot forwarding schedule are proposed for distributed space-frequency coded cooperative communication system with multiple relay nodes over frequency-selective fading channels, including the Least Square (LS) method and the Low rank Linear Minimum Mean Square Error (Lr-LMMSE) method. The cooperative relay nodes forward the pilot vector sent by the source node to the destination in different time slots, so that the superposition of the pilot signals transmitted by different relay nodes is avoided. Theoretical analysis showes that the proposed algorithms achieve all the frequency-domain channel fading coefficients of the multi-relay distributed SF coded cooperative communication system successfully. Simulation results confirme the performance of the proposed channel estimation algorithms, including the high accuracy, extraordinary practicality and the low complexity.
Several frequency-domain channel estimation algorithms based on a new pilot forwarding schedule are proposed for distributed space-frequency coded cooperative communication system with multiple relay nodes over frequency-selective fading channels, including the Least Square (LS) method and the Low rank Linear Minimum Mean Square Error (Lr-LMMSE) method. The cooperative relay nodes forward the pilot vector sent by the source node to the destination in different time slots, so that the superposition of the pilot signals transmitted by different relay nodes is avoided. Theoretical analysis showes that the proposed algorithms achieve all the frequency-domain channel fading coefficients of the multi-relay distributed SF coded cooperative communication system successfully. Simulation results confirme the performance of the proposed channel estimation algorithms, including the high accuracy, extraordinary practicality and the low complexity.
2010, 32(6): 1418-1422.
doi: 10.3724/SP.J.1146.2009.00879
Abstract:
A sub-Nyquist sampling method is presented to reduce the ADC sampling rate in UWB wireless communications. Sampling rate of the proposed method is related to the signal innovation rate, which is about one tenth of the Nyquist rate in conventional Shannon sampling theorem. Fourier transform coefficients of the UWB signals are derived from theoretical analysis based on sub-Nyquist sampling. Then Total Least Squares (TLS) algorithm is proposed to estimate the parameters of the amplitudes and time shifts of impulse signals. The waveform of UWB signals can be reconstructed by convolving the estimated impulse signals with Gaussian monocycle. Simulation and experiment results show that the UWB signals can be accurately reconstructed, and the proposed methods outperform annihilating filter method in the presence of noise.
A sub-Nyquist sampling method is presented to reduce the ADC sampling rate in UWB wireless communications. Sampling rate of the proposed method is related to the signal innovation rate, which is about one tenth of the Nyquist rate in conventional Shannon sampling theorem. Fourier transform coefficients of the UWB signals are derived from theoretical analysis based on sub-Nyquist sampling. Then Total Least Squares (TLS) algorithm is proposed to estimate the parameters of the amplitudes and time shifts of impulse signals. The waveform of UWB signals can be reconstructed by convolving the estimated impulse signals with Gaussian monocycle. Simulation and experiment results show that the UWB signals can be accurately reconstructed, and the proposed methods outperform annihilating filter method in the presence of noise.
Transmit Antenna Selection Based on Approximate Capacity Analysis in Linear Dispersion Codes Systems
2010, 32(6): 1423-1428.
doi: 10.3724/SP.J.1146.2009.00830
Abstract:
In order to reduce the complexity of transmit antenna selection in Multi-Input and Multi- Output(MIMO) systems using Linear Dispersion Codes(LDC), an approximate capacity expression considering the average effect of LDC matrix is derived making use of the characterization of unitary-based parameterization of Linear Transformation Matrix for LDC. Transmit antenna selection algorithms based on approximate capacity can lower the complexity efficiently, because the approximate capacity expression does not involve the operations about higher-order equivalent channel matrix extended in time. From the approximate capacity expression, transmit antenna selection algorithms based on maximum approximate capacity and based on matrix elimination are proposed in this paper separately, and meanwhile approximate capacity expression offers theory support for direct use of some transmit antenna selection algorithms proposed in vertical-bell laboratory layered space-time (V-BLAST) systems. Simulation results suggest that the proposed algorithms can approach the performance of optimal antenna selection algorithm with lower complexity. Compared to the norm and correction-based algorithm proposed in V-BLAST systems, the algorithm based on matrix elimination can get better diversity gain, and outperform the former on Bit Error Rate(BER) performance.
In order to reduce the complexity of transmit antenna selection in Multi-Input and Multi- Output(MIMO) systems using Linear Dispersion Codes(LDC), an approximate capacity expression considering the average effect of LDC matrix is derived making use of the characterization of unitary-based parameterization of Linear Transformation Matrix for LDC. Transmit antenna selection algorithms based on approximate capacity can lower the complexity efficiently, because the approximate capacity expression does not involve the operations about higher-order equivalent channel matrix extended in time. From the approximate capacity expression, transmit antenna selection algorithms based on maximum approximate capacity and based on matrix elimination are proposed in this paper separately, and meanwhile approximate capacity expression offers theory support for direct use of some transmit antenna selection algorithms proposed in vertical-bell laboratory layered space-time (V-BLAST) systems. Simulation results suggest that the proposed algorithms can approach the performance of optimal antenna selection algorithm with lower complexity. Compared to the norm and correction-based algorithm proposed in V-BLAST systems, the algorithm based on matrix elimination can get better diversity gain, and outperform the former on Bit Error Rate(BER) performance.
2010, 32(6): 1429-1434.
doi: 10.3724/SP.J.1146.2009.00848
Abstract:
Through deriving the matrix representations of the critical-sampled Filtered Multi-Tone(FMT) modulation system, a new subchannel frequency-domain equalization algorithm is proposed in this paper to eliminate the Inter-Symbol Interference(ISI) in critical-sampled FMT system. The coefficients of the equalizer are calculated based on Maximizing Subchannel Bit-rate(MSB) rule. Simulation results show that the ABR performance of the proposed algorithm is enhanced 40 percent and 70 percent respectively in comparison with that of the previously proposed frequency domain equalization algorithm based on minimum-mean-square-error rule(LIN) and the DFE equalization algorithm, and the proposed algorithm brings about 3 dB and 5 dB improvement over the LIN and the DFE equalization algorithm in ATTC E channel; in the WLAN Channel, the ABR performance of the proposed algorithm is enhanced 45 percent and 75 percent respectively in comparison with that of the LIN and the DFE equalization algorithm, and the proposed algorithm brings about 6 dB and 10 dB improvement over the LIN and the DFE equalization algorithm.
Through deriving the matrix representations of the critical-sampled Filtered Multi-Tone(FMT) modulation system, a new subchannel frequency-domain equalization algorithm is proposed in this paper to eliminate the Inter-Symbol Interference(ISI) in critical-sampled FMT system. The coefficients of the equalizer are calculated based on Maximizing Subchannel Bit-rate(MSB) rule. Simulation results show that the ABR performance of the proposed algorithm is enhanced 40 percent and 70 percent respectively in comparison with that of the previously proposed frequency domain equalization algorithm based on minimum-mean-square-error rule(LIN) and the DFE equalization algorithm, and the proposed algorithm brings about 3 dB and 5 dB improvement over the LIN and the DFE equalization algorithm in ATTC E channel; in the WLAN Channel, the ABR performance of the proposed algorithm is enhanced 45 percent and 75 percent respectively in comparison with that of the LIN and the DFE equalization algorithm, and the proposed algorithm brings about 6 dB and 10 dB improvement over the LIN and the DFE equalization algorithm.
2010, 32(6): 1435-1440.
doi: 10.3724/SP.J.1146.2009.00695
Abstract:
This paper presents a practical scheme of equal flux beams coverage and frequency multiplex according to CDMA standard utilized by LEO satellites, which can reduce the effect of corner problem and near and far problem. Genetic algorithm is adopted to realize the synthesis of hexagonal antenna, based on sub-array theory. The partition of sub-array in beam-space or element-space can reduce the number of beam-forming coefficients. A multiplex structure for beam-forming network is proposed, which can reduce the resource consumption by 67%. Ultimately a phased array antenna (TX) is designed. The experiment result demonstrates that all the parameters of phased array antenna are consistent with the target of design, which validates the rationality and feasibility of genetic algorithm.
This paper presents a practical scheme of equal flux beams coverage and frequency multiplex according to CDMA standard utilized by LEO satellites, which can reduce the effect of corner problem and near and far problem. Genetic algorithm is adopted to realize the synthesis of hexagonal antenna, based on sub-array theory. The partition of sub-array in beam-space or element-space can reduce the number of beam-forming coefficients. A multiplex structure for beam-forming network is proposed, which can reduce the resource consumption by 67%. Ultimately a phased array antenna (TX) is designed. The experiment result demonstrates that all the parameters of phased array antenna are consistent with the target of design, which validates the rationality and feasibility of genetic algorithm.
2010, 32(6): 1441-1445.
doi: 10.3724/SP.J.1146.2009.00672
Abstract:
Selection Combining (SC) receiver for Fast Frequency-Hopped Binary Frequency-Shift-Keying (FFH/ BFSK) communication systems can reduce the performance degradation caused by interference. The SC receiver model is proposed in the present of Partial Band Noise Jamming (PBNJ). The bit-error probability is evaluated for the receiver over a frequency-nonselective slowly Nakagami-m fading channel with PBNJ and additive white Gaussian noise. A closed-form error probability expression is given. It is shown that the SC receiver with high diversity order is immune to PBNJ and it achieves better performance comparing to several other combining receivers when the jamming power is strong. Under certain channel conditions, there is an optimal diversity order. An adaptive scheme is proposed for improving the performance of SC receiver when the jamming power decreases.
Selection Combining (SC) receiver for Fast Frequency-Hopped Binary Frequency-Shift-Keying (FFH/ BFSK) communication systems can reduce the performance degradation caused by interference. The SC receiver model is proposed in the present of Partial Band Noise Jamming (PBNJ). The bit-error probability is evaluated for the receiver over a frequency-nonselective slowly Nakagami-m fading channel with PBNJ and additive white Gaussian noise. A closed-form error probability expression is given. It is shown that the SC receiver with high diversity order is immune to PBNJ and it achieves better performance comparing to several other combining receivers when the jamming power is strong. Under certain channel conditions, there is an optimal diversity order. An adaptive scheme is proposed for improving the performance of SC receiver when the jamming power decreases.
2010, 32(6): 1446-1451.
doi: 10.3724/SP.J.1146.2009.00834
Abstract:
In order to improve the system performance and reduce the algorithm complexity future, a new better approximate analysis method named equivalent chi-square distribution method is proposed in cooperative communication systems. More accurate theoretical expressions of throughput are derived compared with the traditional equivalent Gaussian distribution method, the effect of throughput on information rate and signal- to-noise ratio is studied, and the optimal information rate parameter R is also given. Analysis and simulation demonstrate that equivalent chi-square distribution method can be effectively applied to the research of cooperative communication systems with the collaborative multiple relays.
In order to improve the system performance and reduce the algorithm complexity future, a new better approximate analysis method named equivalent chi-square distribution method is proposed in cooperative communication systems. More accurate theoretical expressions of throughput are derived compared with the traditional equivalent Gaussian distribution method, the effect of throughput on information rate and signal- to-noise ratio is studied, and the optimal information rate parameter R is also given. Analysis and simulation demonstrate that equivalent chi-square distribution method can be effectively applied to the research of cooperative communication systems with the collaborative multiple relays.
2010, 32(6): 1452-1456.
doi: 10.3724/SP.J.1146.2009.00781
Abstract:
In order to get over the limitation of the GPS(Generalized Processor Sharing) like queuing algorithms which the bound of the queuing delay is so long and unstable that is undesirable for the packets of real-time applications, a new packet queuing and scheduling algorithm is proposed. In this algorithm the competitions of the arrival packets are fine-tuned by means of adding a function of flow urgency degree on the computation of their service tags, so the transmitting priorities of the arrival packets can be tuned according to their real-time applications needs, therefore the queuing delay and the bounds of oscillation are cut down significantly. According as the analysis and the simulation, this packet queuing and scheduling algorithm can resolve the long and unstable packet latencies problem for real-time applications, and shares both the bounded-delay and fairness properties of the GPS like algorithms, and the computation of its system virtual time is simple and efficient.
In order to get over the limitation of the GPS(Generalized Processor Sharing) like queuing algorithms which the bound of the queuing delay is so long and unstable that is undesirable for the packets of real-time applications, a new packet queuing and scheduling algorithm is proposed. In this algorithm the competitions of the arrival packets are fine-tuned by means of adding a function of flow urgency degree on the computation of their service tags, so the transmitting priorities of the arrival packets can be tuned according to their real-time applications needs, therefore the queuing delay and the bounds of oscillation are cut down significantly. According as the analysis and the simulation, this packet queuing and scheduling algorithm can resolve the long and unstable packet latencies problem for real-time applications, and shares both the bounded-delay and fairness properties of the GPS like algorithms, and the computation of its system virtual time is simple and efficient.
2010, 32(6): 1457-1462.
doi: 10.3724/SP.J.1146.2009.00908
Abstract:
CICQ (Combined Input Crosspoint Queued) is a switch fabric with buffers in crosspoints, which brings its nice distributed parallel scheduling property with no internal speedup required. In order to adapt to various traffics in the network environment, and improve performance under nonuniform traffics, a novel efficient scheduling algorithm with longest queue detectingRR-LQD (Round Robin based on Longest Queue Detecting) is proposed. RR-LQD provides fine scalability with the complexity of O(1). The local longest queue being detected and serviced all along guarantees length balance among input queues, which makes RR-LQD adapt to the network environment of nonuniform traffic automatically. The simulation results show that the RR-LQD can achieve 100% throughput and low delay under various uniform and non-uniform traffics. In this paper, the arbiter of RR-LQD is implemented by a FPGA chip. That proves RR-LQD can meet the demands of high-speed and large capacity switching fabrics.
CICQ (Combined Input Crosspoint Queued) is a switch fabric with buffers in crosspoints, which brings its nice distributed parallel scheduling property with no internal speedup required. In order to adapt to various traffics in the network environment, and improve performance under nonuniform traffics, a novel efficient scheduling algorithm with longest queue detectingRR-LQD (Round Robin based on Longest Queue Detecting) is proposed. RR-LQD provides fine scalability with the complexity of O(1). The local longest queue being detected and serviced all along guarantees length balance among input queues, which makes RR-LQD adapt to the network environment of nonuniform traffic automatically. The simulation results show that the RR-LQD can achieve 100% throughput and low delay under various uniform and non-uniform traffics. In this paper, the arbiter of RR-LQD is implemented by a FPGA chip. That proves RR-LQD can meet the demands of high-speed and large capacity switching fabrics.
2010, 32(6): 1463-1468.
doi: 10.3724/SP.J.1146.2008.01486
Abstract:
In this paper an algorithm called IQoE2QoS(Improved QoE to QoS) is presented. This algorithm focus on QoE how to map to QoS based on fuzzy theory. IQoE2QoS presented has three targets: it can give the association degree among indications through calculating the entropy in large data sets. Its purpose is to translate user perception acquired from large experience datasets into pieces of metrics which can be used in lower level QoS. In this paper, a proposition not only illustrating the mapping between QoE and QoS but also the mapping between QoE and SLA is proposed. Emulation shows that IQoE2QoS can improve classification accuracy two to three times than line regression algorithm.
In this paper an algorithm called IQoE2QoS(Improved QoE to QoS) is presented. This algorithm focus on QoE how to map to QoS based on fuzzy theory. IQoE2QoS presented has three targets: it can give the association degree among indications through calculating the entropy in large data sets. Its purpose is to translate user perception acquired from large experience datasets into pieces of metrics which can be used in lower level QoS. In this paper, a proposition not only illustrating the mapping between QoE and QoS but also the mapping between QoE and SLA is proposed. Emulation shows that IQoE2QoS can improve classification accuracy two to three times than line regression algorithm.
2010, 32(6): 1469-1474.
doi: 10.3724/SP.J.1146.2009.00720
Abstract:
In this paper, a dynamic reputation evaluation model is proposed to meet the characteristic and security requirement in hierarchical Ad hoc networks. In this model, the reputation relationship is defined with the consideration of related nodes roles and function, and the reputation evaluation mechanism is built based on the correlation among nodes to evaluate and update reputation information of nodes with different roles. The cluster reputation is monitored by the cluster head in this model to solve the slow convergence speed issue in traditional reputation calculation. Simulation results show that, compared to traditional reputation evaluation models, the model proposed in this paper can more real-time and accurately reflect the security status in hierarchical Ad hoc networks.
In this paper, a dynamic reputation evaluation model is proposed to meet the characteristic and security requirement in hierarchical Ad hoc networks. In this model, the reputation relationship is defined with the consideration of related nodes roles and function, and the reputation evaluation mechanism is built based on the correlation among nodes to evaluate and update reputation information of nodes with different roles. The cluster reputation is monitored by the cluster head in this model to solve the slow convergence speed issue in traditional reputation calculation. Simulation results show that, compared to traditional reputation evaluation models, the model proposed in this paper can more real-time and accurately reflect the security status in hierarchical Ad hoc networks.
2010, 32(6): 1475-1479.
doi: 10.3724/SP.J.1146.2009.00521
Abstract:
In this paper, the optimum numbers of cooperative nodes and modulation methods are analyzed to minimize the total energy consumption in a cooperative wireless sensor networks, which is power-limited. An exact closed-form expression is derived for the average BER in Rayleigh-fading channels for both BPSK and MQAM modulations, and then the energy of cooperative system is analyzed. Finally a synthetic optimization of modulation and number of cooperative nodes is presented to minimize the total energy consumption. Comparisons with the fix-rate or fix numbers of cooperative nodes systems demonstrate the significant energy saving of the synthetic optimization.
In this paper, the optimum numbers of cooperative nodes and modulation methods are analyzed to minimize the total energy consumption in a cooperative wireless sensor networks, which is power-limited. An exact closed-form expression is derived for the average BER in Rayleigh-fading channels for both BPSK and MQAM modulations, and then the energy of cooperative system is analyzed. Finally a synthetic optimization of modulation and number of cooperative nodes is presented to minimize the total energy consumption. Comparisons with the fix-rate or fix numbers of cooperative nodes systems demonstrate the significant energy saving of the synthetic optimization.
2010, 32(6): 1480-1484.
doi: 10.3724/SP.J.1146.2009.00892
Abstract:
With the characteristics of self-organizing, self-management and limited energy of WSN, the security is a great challenge. In this paper, a novel Efficient Broadcast Key Management Policy named as EBKMP is proposed. It divides broadcast trees into groups, and the principle of minimizing the hamming distance between neighbor groups is adopted in keys distribution, which enhances security and reduces the overhead caused by the changes of group members. Compared with present key management policies, EBKMP can improve the efficiency in communication and storage, and resist collusion attack effectively.
With the characteristics of self-organizing, self-management and limited energy of WSN, the security is a great challenge. In this paper, a novel Efficient Broadcast Key Management Policy named as EBKMP is proposed. It divides broadcast trees into groups, and the principle of minimizing the hamming distance between neighbor groups is adopted in keys distribution, which enhances security and reduces the overhead caused by the changes of group members. Compared with present key management policies, EBKMP can improve the efficiency in communication and storage, and resist collusion attack effectively.
2010, 32(6): 1489-1492.
doi: 10.3724/SP.J.1146.2009.00859
Abstract:
The concept of dynamic Distortion-Compensated Quantization Index Modulation (dynamic DC-QIM) is proposed, which differs from the conventional DC-QIM in whether or not quantization step size and DC parameter are changeable. Firstly, the condition satisfying the reversibility of dynamic DC-QIM is deduced. Then, the allowable range of DC parameter is derived. Finally, the procedure of reversible data hiding algorithm based on dynamic DC-QIM is designed. Its data hiding rate can achieve as high as 1bpp in a single iteration, higher than its former counterparts. Furthermore, the use of dynamic characteristic is in favor of preventing its parameters from being disclosed. Experimental results show that it not only accurately decodes the secret information, but also perfectly restores the original cover, regardless of initial conditions.
The concept of dynamic Distortion-Compensated Quantization Index Modulation (dynamic DC-QIM) is proposed, which differs from the conventional DC-QIM in whether or not quantization step size and DC parameter are changeable. Firstly, the condition satisfying the reversibility of dynamic DC-QIM is deduced. Then, the allowable range of DC parameter is derived. Finally, the procedure of reversible data hiding algorithm based on dynamic DC-QIM is designed. Its data hiding rate can achieve as high as 1bpp in a single iteration, higher than its former counterparts. Furthermore, the use of dynamic characteristic is in favor of preventing its parameters from being disclosed. Experimental results show that it not only accurately decodes the secret information, but also perfectly restores the original cover, regardless of initial conditions.
2010, 32(6): 1493-1496.
doi: 10.3724/SP.J.1146.2009.00776
Abstract:
Considering the issue of angle ambiguity in estimating the directions of arrivals, this paper analyses the feasibility of ambiguity solving with virtual arrays using the virtual array transformation algorithm and the virtual array algorithm based on least squares estimator. Computer simulations confirm that the data of virtual array depends on the sector, and such algorithms can not solve the angle ambiguity problem effectively in this sense.
Considering the issue of angle ambiguity in estimating the directions of arrivals, this paper analyses the feasibility of ambiguity solving with virtual arrays using the virtual array transformation algorithm and the virtual array algorithm based on least squares estimator. Computer simulations confirm that the data of virtual array depends on the sector, and such algorithms can not solve the angle ambiguity problem effectively in this sense.
2010, 32(6): 1497-1500.
doi: 10.3724/SP.J.1146.2008.00265
Abstract:
In the application of distributed-satellite INSAR system for velocity-measurement of ground moving targets, due to the satellite clusters flying around, the flying tracks of all satellites are not parallel and their velocity vectors are different. This may cause the along-track baselines time-variety, affect the interferometric phase map and result in velocity and position measurement errors. This paper analyzes the clusters actual flying tracks and the influence of non-parallel flying to the ATI-SAR velocity-measurements precision, establishes the velocity-error model caused by non-parallel flying, proposes two novel methods to improve the measurement accuracy and obtain precise measurement. Finally, the simulation experimental results prove the conclusion proposed.
In the application of distributed-satellite INSAR system for velocity-measurement of ground moving targets, due to the satellite clusters flying around, the flying tracks of all satellites are not parallel and their velocity vectors are different. This may cause the along-track baselines time-variety, affect the interferometric phase map and result in velocity and position measurement errors. This paper analyzes the clusters actual flying tracks and the influence of non-parallel flying to the ATI-SAR velocity-measurements precision, establishes the velocity-error model caused by non-parallel flying, proposes two novel methods to improve the measurement accuracy and obtain precise measurement. Finally, the simulation experimental results prove the conclusion proposed.
2010, 32(6): 1501-1504.
doi: 10.3724/SP.J.1146.2009.00736
Abstract:
A rigorous analysis of Split Rring Resonator (SRR) metamaterials is presented for three different electromagnetic field polarization and propagation directions to establish the SRR resonance behaviors. The Smiths parameter retrieval method is then extended to Floquet mode analysis, and the S parameters from the two methods are compared. The resonances of SRR with different orientation is investigated to testify the proposed analysis. Compared with traditional methods, parameter retrieval method based on Floquet mode analysis reduces greatly the time to calculate the S parameters, thus it is more convenient for the analysis of metamaterial bianisotopic effects.
A rigorous analysis of Split Rring Resonator (SRR) metamaterials is presented for three different electromagnetic field polarization and propagation directions to establish the SRR resonance behaviors. The Smiths parameter retrieval method is then extended to Floquet mode analysis, and the S parameters from the two methods are compared. The resonances of SRR with different orientation is investigated to testify the proposed analysis. Compared with traditional methods, parameter retrieval method based on Floquet mode analysis reduces greatly the time to calculate the S parameters, thus it is more convenient for the analysis of metamaterial bianisotopic effects.
2010, 32(6): 1505-1509.
doi: 10.3724/SP.J.1146.2008.01186
Abstract:
An improved QR based detection algorithm is proposed for use in the Multiple- Input Multiple-Output (MIMO) communication systems. The method does not require the pseudo inverse of the channel matrix. The probability of error propagation is reduced through serial interference canceling; the minimum error probability signal is removed layer by layer. It has less computational complexity than ordered QR based detection and ordered BLAST detection .Simulation shows that it outperforms the classic BLAST and ordered，suboptimal ordered QR based detection algorithm. In the uncoded 44 MIMO system with QPSK modulation, there proposed algorithm outperforms ZF-VBLAST by 2.5 dB and outperforms the sorted QR algorithm 5 dB at a BER of 10-3.
An improved QR based detection algorithm is proposed for use in the Multiple- Input Multiple-Output (MIMO) communication systems. The method does not require the pseudo inverse of the channel matrix. The probability of error propagation is reduced through serial interference canceling; the minimum error probability signal is removed layer by layer. It has less computational complexity than ordered QR based detection and ordered BLAST detection .Simulation shows that it outperforms the classic BLAST and ordered，suboptimal ordered QR based detection algorithm. In the uncoded 44 MIMO system with QPSK modulation, there proposed algorithm outperforms ZF-VBLAST by 2.5 dB and outperforms the sorted QR algorithm 5 dB at a BER of 10-3.
2010, 32(6): 1510-1514.
doi: 10.3724/SP.J.1146.2008.00865
Abstract:
This paper studies the constellations of 22n+1-Quadrature Amplitude Modulation (QAM), and proposed a square QAM constellation which can build its mapping list according to the Gray coding rules. To compare the square constellation with the cross constellation and the rectangle constellation, the signal power efficiency of these three constellations and their BER performance is simulated, taking 32QAM for example. The simulation results show that square constellation has better BER performance than the other two. Moreover, the signal power efficient of square constellation is as well as that of cross constellation and rectangle constellation to the multi-carrier communication systems.
This paper studies the constellations of 22n+1-Quadrature Amplitude Modulation (QAM), and proposed a square QAM constellation which can build its mapping list according to the Gray coding rules. To compare the square constellation with the cross constellation and the rectangle constellation, the signal power efficiency of these three constellations and their BER performance is simulated, taking 32QAM for example. The simulation results show that square constellation has better BER performance than the other two. Moreover, the signal power efficient of square constellation is as well as that of cross constellation and rectangle constellation to the multi-carrier communication systems.
2010, 32(6): 1515-1519.
doi: 10.3724/SP.J.1146.2009.00651
Abstract:
This paper presents a high-speed GCM architecture, which is suitable for IEEE 802.1AE protocol. The core modules of GCM include AES and Ghash. In Ghash module, a new parallel multiply-adder is proposed, which can handle several sets of data at the same time without knowing the total number of data blocks in advance. To support constant key changes in each clock cycle, loop-unrolling structure is used in KeyExpansion module of AES. A GCM encryptor design example with 2-parallel Ghash is implemented and the performance is evaluated by utilizing Fujitsu 0.13 m 1.2 V 1P8M CMOS technology and a very high throughput of 97.9 Gbps is obtained with 547 Kgates, operating at 764.5 MHz.
This paper presents a high-speed GCM architecture, which is suitable for IEEE 802.1AE protocol. The core modules of GCM include AES and Ghash. In Ghash module, a new parallel multiply-adder is proposed, which can handle several sets of data at the same time without knowing the total number of data blocks in advance. To support constant key changes in each clock cycle, loop-unrolling structure is used in KeyExpansion module of AES. A GCM encryptor design example with 2-parallel Ghash is implemented and the performance is evaluated by utilizing Fujitsu 0.13 m 1.2 V 1P8M CMOS technology and a very high throughput of 97.9 Gbps is obtained with 547 Kgates, operating at 764.5 MHz.
2010, 32(6): 1520-1524.
doi: 10.3724/SP.J.1146.2009.01092
Abstract:
In the paper, the existence of an Nash equilibrium in the network congestion mode induced by MAC layer competition is proved firstly; Secondly, a cross-layer congestion-control mechanism named WCS is proposed based on WOLF-PHC learning strategy. WCS selects a couple of decoupled node as next-hop nodes at routing layer; Meanwhile, sources traffic is spitted and forwarded at MAC layer, which improves the space reusing efficiency of link. Simulation result shows that: without any exchanging information, optimum split-flow point of source node will be sought by WOLF-PHC in order to maximize the network throughput; Furthermore, WOLF-PHC will discover new optimum split-flow point in order to adapt to new network environment.
In the paper, the existence of an Nash equilibrium in the network congestion mode induced by MAC layer competition is proved firstly; Secondly, a cross-layer congestion-control mechanism named WCS is proposed based on WOLF-PHC learning strategy. WCS selects a couple of decoupled node as next-hop nodes at routing layer; Meanwhile, sources traffic is spitted and forwarded at MAC layer, which improves the space reusing efficiency of link. Simulation result shows that: without any exchanging information, optimum split-flow point of source node will be sought by WOLF-PHC in order to maximize the network throughput; Furthermore, WOLF-PHC will discover new optimum split-flow point in order to adapt to new network environment.
2010, 32(6): 1485-1488.
doi: 10.3724/SP.J.1146.2009.01396
Abstract:
Knapsack-type public-key cryptosystem is one of several earliest public key cryptosystems, and it is very important to analyze their security. This article argues the security of two new knapsack cryptosystems which are secure against Shamirs attack and low density attack. A new attack method is proposed, and it is showed that can be used a polynomial time algorithm to find the secret keys with high probability, and hence break the new knapsack cryptosystems.
Knapsack-type public-key cryptosystem is one of several earliest public key cryptosystems, and it is very important to analyze their security. This article argues the security of two new knapsack cryptosystems which are secure against Shamirs attack and low density attack. A new attack method is proposed, and it is showed that can be used a polynomial time algorithm to find the secret keys with high probability, and hence break the new knapsack cryptosystems.
