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2005 Vol. 27, No. 2
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2005, 27(2): 169-173.
Abstract:
The paper proposes an effective algorithm to estimate the spread spectrum sequence of Direct Spread Spectrum Sequence (DSSS) signal, which is suitable for non-cooperative communication systems. Two measurement functions are suggested. One is used for sequence synchronization; the other is used for sequence estimation chip by chip. Only simple complex addition and multiplication are required in this algorithm. Both theoretic analysis and computer simulations show the effectiveness of this algorithm.
The paper proposes an effective algorithm to estimate the spread spectrum sequence of Direct Spread Spectrum Sequence (DSSS) signal, which is suitable for non-cooperative communication systems. Two measurement functions are suggested. One is used for sequence synchronization; the other is used for sequence estimation chip by chip. Only simple complex addition and multiplication are required in this algorithm. Both theoretic analysis and computer simulations show the effectiveness of this algorithm.
2005, 27(2): 173-176.
Abstract:
In this paper, a low-complexity blind channel estimation technique is proposed for long-code MIMO CDMA systems. Simply based on the first-order statistic of the decorrelating matched filter output, the channel parameters can be estimated effectively without training sequences. Computer simulations show that the proposed algorithm offers good estimation behavior for MIMO CDMA systems.
In this paper, a low-complexity blind channel estimation technique is proposed for long-code MIMO CDMA systems. Simply based on the first-order statistic of the decorrelating matched filter output, the channel parameters can be estimated effectively without training sequences. Computer simulations show that the proposed algorithm offers good estimation behavior for MIMO CDMA systems.
2005, 27(2): 177-180.
Abstract:
In practice, the channel state in Nakagami fading needs to be estimated for many optimum signal processing techniques. A new algorithm is put forward on the basis of the higher order statistical analysis, which is simple and effective, furthermore, a new all-blind channel state estimation algorithm in Nakagami fading is presented for the first time, and its validity is proved by simulations.
In practice, the channel state in Nakagami fading needs to be estimated for many optimum signal processing techniques. A new algorithm is put forward on the basis of the higher order statistical analysis, which is simple and effective, furthermore, a new all-blind channel state estimation algorithm in Nakagami fading is presented for the first time, and its validity is proved by simulations.
2005, 27(2): 181-183.
Abstract:
A new algorithm is put forward on the basis of the higher order statistic analysis, and it is much simpler and more effective than the previous algorithm, and its validity is proved by the sensitivity simulation of SNR estimation to decoding quality of Turbo code.
A new algorithm is put forward on the basis of the higher order statistic analysis, and it is much simpler and more effective than the previous algorithm, and its validity is proved by the sensitivity simulation of SNR estimation to decoding quality of Turbo code.
2005, 27(2): 184-188.
Abstract:
An algorithm is presented for Direction-Of-Arrival (DOA) estimation of nonstationary signals impinging on the antenna array. The proposed method establishes a simplified array signal model in the time-frequency (t-f) domain by evaluating the cross Pseudo Wigner-Ville Distributions (PWVD) between the outputs of the reference element and other elements of the array, and provides a signal selective DOA estimator based on the t-f maximum likelihood. Compared with the Spatial Time-Frequency Distributions (STFD) matrices-based methods, the proposed method can make full use of the crossterms in the t-f plane, and the computational load is significantly reduced. Simulations are provided to demonstrate the effectiveness of the method.
An algorithm is presented for Direction-Of-Arrival (DOA) estimation of nonstationary signals impinging on the antenna array. The proposed method establishes a simplified array signal model in the time-frequency (t-f) domain by evaluating the cross Pseudo Wigner-Ville Distributions (PWVD) between the outputs of the reference element and other elements of the array, and provides a signal selective DOA estimator based on the t-f maximum likelihood. Compared with the Spatial Time-Frequency Distributions (STFD) matrices-based methods, the proposed method can make full use of the crossterms in the t-f plane, and the computational load is significantly reduced. Simulations are provided to demonstrate the effectiveness of the method.
2005, 27(2): 189-191.
Abstract:
A new method for Direction of Arriving (DOA) Estimation-Phase Matched Theory (PMT) is introduced, which computation complexity is simple and performance is unaffected by unknown correlated noise. Compared with energy criterion, a robust criterion based on SVD improves the bias and variance of estimation and the simplicity is still kept. Computer simulation shows that the criterions performance approximates MUSIC algorithm at high SNR and exceeds it at low SNR. Specially, this algorithm still has good performance under unknown correlated noise.
A new method for Direction of Arriving (DOA) Estimation-Phase Matched Theory (PMT) is introduced, which computation complexity is simple and performance is unaffected by unknown correlated noise. Compared with energy criterion, a robust criterion based on SVD improves the bias and variance of estimation and the simplicity is still kept. Computer simulation shows that the criterions performance approximates MUSIC algorithm at high SNR and exceeds it at low SNR. Specially, this algorithm still has good performance under unknown correlated noise.
2005, 27(2): 192-196.
Abstract:
Vertical-Bell Labs Layered Space-Time (V-BLAST) detection algorithm comprises forward and reverse ones according to different detection orders. Combining both algorithms, a novel detection algorithm is presented in this paper in view of the characters of adaptive modulation. New algorithm first detects the saturated channel with maximum modulation size, then detects the invalid channel which does not meet the minimum SNR threshold, finally detects the remaining channel as the criteria minimizing distance between post-detection SNR and threshold set. Simulation results show that the spectral efficiencies of proposed algorithm tend to forward or reverse order at high or low SNR respectively, and outperform the both at middle SNR.
Vertical-Bell Labs Layered Space-Time (V-BLAST) detection algorithm comprises forward and reverse ones according to different detection orders. Combining both algorithms, a novel detection algorithm is presented in this paper in view of the characters of adaptive modulation. New algorithm first detects the saturated channel with maximum modulation size, then detects the invalid channel which does not meet the minimum SNR threshold, finally detects the remaining channel as the criteria minimizing distance between post-detection SNR and threshold set. Simulation results show that the spectral efficiencies of proposed algorithm tend to forward or reverse order at high or low SNR respectively, and outperform the both at middle SNR.
2005, 27(2): 197-201.
Abstract:
Automatic modulation recognition is an important research area for the receiver design in the non-cooperative communication system. A digital modulation recognition algorithm is proposed in this paper for the engineering application. Contrast to other algorithm, this one is very simple to be calculated on-line and it also has a good recognition rate in the low SNR environment, furthermore the effect of symbol shape to the parameter extraction has been considered, which can satisfy the need of engineering.
Automatic modulation recognition is an important research area for the receiver design in the non-cooperative communication system. A digital modulation recognition algorithm is proposed in this paper for the engineering application. Contrast to other algorithm, this one is very simple to be calculated on-line and it also has a good recognition rate in the low SNR environment, furthermore the effect of symbol shape to the parameter extraction has been considered, which can satisfy the need of engineering.
2005, 27(2): 202-205.
Abstract:
This paper deduces the NDA SNR estimation algorithm for QAM signals in additive Gaussian white noise channel and on the condition of the equivalent a priori probability of transition signals positioning on every constellation point by using statistics. And the detail analysis and computer simulation for 128QAM signals are done. It is proved that the whole range interested in practice can be estimated by this algorithm.
This paper deduces the NDA SNR estimation algorithm for QAM signals in additive Gaussian white noise channel and on the condition of the equivalent a priori probability of transition signals positioning on every constellation point by using statistics. And the detail analysis and computer simulation for 128QAM signals are done. It is proved that the whole range interested in practice can be estimated by this algorithm.
2005, 27(2): 206-209.
Abstract:
The kurtosis based ICA approach is analyzed particularly and the geometrical explanation of this approach is presented in the paper. Furthermore, we elucidate the reasons of the indeterminacy of ICA solutions and explain the probability property by analyzing the process for finding out the ICA solutions. These analytic results and conclusions are also benefit to the study on other ICA methods.
The kurtosis based ICA approach is analyzed particularly and the geometrical explanation of this approach is presented in the paper. Furthermore, we elucidate the reasons of the indeterminacy of ICA solutions and explain the probability property by analyzing the process for finding out the ICA solutions. These analytic results and conclusions are also benefit to the study on other ICA methods.
2005, 27(2): 210-213.
Abstract:
A special Modulation-Induced-Cyclostationarity (MIC) scheme is designed for the identification and equalization of FIR single channel. The scheme includes channel order determination and has the properties of interference-rejection capabilities. With the transmit power constant, the receiver needs one antenna only. The cyclic Wiener equalizer is given based on the estimated channel, which is capable of interference rejection.
A special Modulation-Induced-Cyclostationarity (MIC) scheme is designed for the identification and equalization of FIR single channel. The scheme includes channel order determination and has the properties of interference-rejection capabilities. With the transmit power constant, the receiver needs one antenna only. The cyclic Wiener equalizer is given based on the estimated channel, which is capable of interference rejection.
2005, 27(2): 214-217.
Abstract:
To combine Low-Density Parity-Check (LDPC) codes with MQAM constellation, a scheme of Belief Propagation Coded Modulation with Iterative Decoding (BPCM-ID) is proposed. The Pair Error Probability(PEP) performance in Rayleigh channel and design rules for MQAM constellation are also analyzed. Both outer and inner iterations are used to avoid too much errors feedback which may cause decoding failure. The scheme introduces the check equations of LDPC codes to terminate both iterations which reduce the average decoding complexities greatly. Simulation results show that the proposed BPCM-ID is effective and performs better than the other three schemes.
To combine Low-Density Parity-Check (LDPC) codes with MQAM constellation, a scheme of Belief Propagation Coded Modulation with Iterative Decoding (BPCM-ID) is proposed. The Pair Error Probability(PEP) performance in Rayleigh channel and design rules for MQAM constellation are also analyzed. Both outer and inner iterations are used to avoid too much errors feedback which may cause decoding failure. The scheme introduces the check equations of LDPC codes to terminate both iterations which reduce the average decoding complexities greatly. Simulation results show that the proposed BPCM-ID is effective and performs better than the other three schemes.
2005, 27(2): 218-220.
Abstract:
A new shortwave frequency hopping codes based on difference frequency hopping transform function which depended on logistic map is presented. The performance of the frequency hopping codes is researched .The results indicate that it has better randomicity, uniformity, balance, and higher privacy because of the character of chaos.
A new shortwave frequency hopping codes based on difference frequency hopping transform function which depended on logistic map is presented. The performance of the frequency hopping codes is researched .The results indicate that it has better randomicity, uniformity, balance, and higher privacy because of the character of chaos.
2005, 27(2): 221-225.
Abstract:
In this paper, a spectrum-efficient differential space-time transmission scheme is presented for Code-Division Multiple-Access (CDMA) systems. Consider a multiuser environment with M synchronous co-channel users, each is equipped with 2 transmit antennas. Assuming the receiver uses N2 receive antennas, this scheme will exploit decorrelating detectors and receive antenna diversity to separate M users. Then a noncoherent decoder is derived for flat Rayieigh fading channels, which can provide a minimum diversity order of 2x(jV-1) to each co-channel user. Compared with the existing differential space-time coded CDMA systems, the proposed scheme has two main advantages: Firstly, only by deploying an additional receive antenna, it can effectively improve the system performance under the condition that the spectrum efficiency is increased by 1/3; secondly, it has only linear decoding complexity.
In this paper, a spectrum-efficient differential space-time transmission scheme is presented for Code-Division Multiple-Access (CDMA) systems. Consider a multiuser environment with M synchronous co-channel users, each is equipped with 2 transmit antennas. Assuming the receiver uses N2 receive antennas, this scheme will exploit decorrelating detectors and receive antenna diversity to separate M users. Then a noncoherent decoder is derived for flat Rayieigh fading channels, which can provide a minimum diversity order of 2x(jV-1) to each co-channel user. Compared with the existing differential space-time coded CDMA systems, the proposed scheme has two main advantages: Firstly, only by deploying an additional receive antenna, it can effectively improve the system performance under the condition that the spectrum efficiency is increased by 1/3; secondly, it has only linear decoding complexity.
2005, 27(2): 226-229.
Abstract:
This paper mainly deals with the capacity of MIMO system with memory. With assumption that MIMO channels with memory are independently Rayleigh and block-fading, a closed-form stochastic formula of the MIMO system with memory is derived with the stochastic analysis and multivariate statistical theory. The analysis and simulations show that, under the assumptions of same transceiver antenna number and perfectly receiving signal processing, the capacity of MIMO system with memory is higher than that without memory and increases as the number of memory increases.
This paper mainly deals with the capacity of MIMO system with memory. With assumption that MIMO channels with memory are independently Rayleigh and block-fading, a closed-form stochastic formula of the MIMO system with memory is derived with the stochastic analysis and multivariate statistical theory. The analysis and simulations show that, under the assumptions of same transceiver antenna number and perfectly receiving signal processing, the capacity of MIMO system with memory is higher than that without memory and increases as the number of memory increases.
2005, 27(2): 230-234.
Abstract:
The traffic load is estimated based on the optimally combined traffic load forecasting model for cellular mobile communications system, The results are then used to derive the hot cells and cold cells due to the Quality of Service (QoS) requirement, an Optimized Hybrid Channel Assignment (OHCA) scheme is proposed and the ratio of active channels and static channels is derived. The analysis indicates that the ratio is bounded by the traffic fluctuation and QoS requirement. Simulation results show that the forecasting model can reduce the prediction error and yield higher forecasting precision compared to using only one method, and OHCA is shown to be superior to the current FCA and DCA in terms of call blocking probability and spectrum utilization. The scheme can be used to handle the hot spot case, and is therefore an attractive scheme for practical systems.
The traffic load is estimated based on the optimally combined traffic load forecasting model for cellular mobile communications system, The results are then used to derive the hot cells and cold cells due to the Quality of Service (QoS) requirement, an Optimized Hybrid Channel Assignment (OHCA) scheme is proposed and the ratio of active channels and static channels is derived. The analysis indicates that the ratio is bounded by the traffic fluctuation and QoS requirement. Simulation results show that the forecasting model can reduce the prediction error and yield higher forecasting precision compared to using only one method, and OHCA is shown to be superior to the current FCA and DCA in terms of call blocking probability and spectrum utilization. The scheme can be used to handle the hot spot case, and is therefore an attractive scheme for practical systems.
2005, 27(2): 235-238.
Abstract:
Group signature schemes allow a group member to anonymously sign on groups behalf. Moreover, in case of anonymity misuse.a group manager can recover the issuer of a signature. This paper analyzes the security of two group signature schemes recently proposed respectively by Posescu (2000) and Wang Xiaoming (2003), and shows that both schemes are universally forgeable, that is, anyone (not necessarily a group member) is able to produce a valid group signature on an arbitrary message, which cannot be traced by the group manager. So both schemes are insecure.
Group signature schemes allow a group member to anonymously sign on groups behalf. Moreover, in case of anonymity misuse.a group manager can recover the issuer of a signature. This paper analyzes the security of two group signature schemes recently proposed respectively by Posescu (2000) and Wang Xiaoming (2003), and shows that both schemes are universally forgeable, that is, anyone (not necessarily a group member) is able to produce a valid group signature on an arbitrary message, which cannot be traced by the group manager. So both schemes are insecure.
2005, 27(2): 239-242.
Abstract:
This paper investigates the channel estimation and interpolation technique in digital video broadcasting COFDM demodulation scheme. To combat the OFDM symbol timing synchronization offset error,it proposes two channel estimation methods suitable for the comb-type pilot scheme.and the analyse of performance and adaptation is also presented.
This paper investigates the channel estimation and interpolation technique in digital video broadcasting COFDM demodulation scheme. To combat the OFDM symbol timing synchronization offset error,it proposes two channel estimation methods suitable for the comb-type pilot scheme.and the analyse of performance and adaptation is also presented.
2005, 27(2): 243-246.
Abstract:
A registration method, IDMBR (Improved DistanceMovement-Based Registration) which combines advantages of distance-based and movement-based registration strategies, is presented in this paper. When a Mobile Terminal (MT) registers, the system transfers some neighboring cells relative information to it, so that the MT can learn the structure of nearby cells. The IDMBR resolves the frequent registration problem resulted from MTs moving back-and-forth at boundary cells in the ordinary dynamical registration schemes. The method can be implemented easily and is very feasible.
A registration method, IDMBR (Improved DistanceMovement-Based Registration) which combines advantages of distance-based and movement-based registration strategies, is presented in this paper. When a Mobile Terminal (MT) registers, the system transfers some neighboring cells relative information to it, so that the MT can learn the structure of nearby cells. The IDMBR resolves the frequent registration problem resulted from MTs moving back-and-forth at boundary cells in the ordinary dynamical registration schemes. The method can be implemented easily and is very feasible.
2005, 27(2): 247-250.
Abstract:
Based on the concept of multi-hop transmission, a multi-hop macro-diversity is presented. In pure lognormal and Rayleigh-lognonnal composite fading channels, a hexagonal macro-diversity cellular system is investigated. The Maximum Ratio Combing (MRC) is considered for the uplink analysis of the Bit Error Rate (BER) for DPSK. Numerical results show that the performance of the new system outperforms that of the conventional single-hop macro-diversity system. The multi-hop relaying can enhance the robustness of system performance to the different location of one mobile station, and it is benefit to reliable communication of the radio link.
Based on the concept of multi-hop transmission, a multi-hop macro-diversity is presented. In pure lognormal and Rayleigh-lognonnal composite fading channels, a hexagonal macro-diversity cellular system is investigated. The Maximum Ratio Combing (MRC) is considered for the uplink analysis of the Bit Error Rate (BER) for DPSK. Numerical results show that the performance of the new system outperforms that of the conventional single-hop macro-diversity system. The multi-hop relaying can enhance the robustness of system performance to the different location of one mobile station, and it is benefit to reliable communication of the radio link.
2005, 27(2): 251-255.
Abstract:
An optimal rate control scheme, which is refered to as Mores, is proposed in this paper. Mores can achieve system optimality of social welfare maximization by means of well-designed link pricing function, which is testified experimentally and theoretically. Furthermore, aMorcs, the adaptive version of Mores, is proposed. Since aMorcs does not need the participation of links, it can be implemented more easily. Experimentations testify that aMorcs is similar in property to Mores.
An optimal rate control scheme, which is refered to as Mores, is proposed in this paper. Mores can achieve system optimality of social welfare maximization by means of well-designed link pricing function, which is testified experimentally and theoretically. Furthermore, aMorcs, the adaptive version of Mores, is proposed. Since aMorcs does not need the participation of links, it can be implemented more easily. Experimentations testify that aMorcs is similar in property to Mores.
2005, 27(2): 256-258.
Abstract:
An improved rebound jamming way named Random Delay Rebound Jamming (RDRJ) to SAR (Synthetic Aperture Radar) is investigated. Not like the normal rebound jamming, the jammers delay time is set randomly between every pulse. The disturbing signal is Linearly Frequency Modulated (LFM) in range direction and not in azimuth direction. The analyses and computer simulation show that the RDRJ method provides a good way to jamming SAR. The advantage of the RDRJ is analyzed finally.
An improved rebound jamming way named Random Delay Rebound Jamming (RDRJ) to SAR (Synthetic Aperture Radar) is investigated. Not like the normal rebound jamming, the jammers delay time is set randomly between every pulse. The disturbing signal is Linearly Frequency Modulated (LFM) in range direction and not in azimuth direction. The analyses and computer simulation show that the RDRJ method provides a good way to jamming SAR. The advantage of the RDRJ is analyzed finally.
2005, 27(2): 259-261.
Abstract:
For the problem of multi-baseline interferometer in wideband direction finding, a algorithm of solving multi-baseline interferometer phase difference ambiguity based on Chinese remainder theorem is given and the condition of correctly solving ambiguity in noisy circumstance is studied. The algorithm selects baseline length satisfied stagger qualification, thereby solving conflict between accuracy of direction finding and maximum unambiguity angle. The performance of the algorithm is effectively demonstrated by computer simulation.
For the problem of multi-baseline interferometer in wideband direction finding, a algorithm of solving multi-baseline interferometer phase difference ambiguity based on Chinese remainder theorem is given and the condition of correctly solving ambiguity in noisy circumstance is studied. The algorithm selects baseline length satisfied stagger qualification, thereby solving conflict between accuracy of direction finding and maximum unambiguity angle. The performance of the algorithm is effectively demonstrated by computer simulation.
2005, 27(2): 262-265.
Abstract:
The fundaments and computation procedures of three algorithms for SAR raw signal generation-RTPC, RFPC and 2DFFTare introduced. A quantitive comparison of these algorithms is emphatically studied on the aspects of error analysis, time and space evaluation. The simulation tests of these algorithms have been implemented using the system parameters of an X-band SAR. Both the theoretical analyses and the emulational results indicate that the third one is more practicable basing on its concise and efficient description and readability, as well as high accuracy of its result.
The fundaments and computation procedures of three algorithms for SAR raw signal generation-RTPC, RFPC and 2DFFTare introduced. A quantitive comparison of these algorithms is emphatically studied on the aspects of error analysis, time and space evaluation. The simulation tests of these algorithms have been implemented using the system parameters of an X-band SAR. Both the theoretical analyses and the emulational results indicate that the third one is more practicable basing on its concise and efficient description and readability, as well as high accuracy of its result.
2005, 27(2): 266-268.
Abstract:
A new unwrapping algorithm-Nearest Point Linking (NPL) algorithm is presented based on the Goldstein algorithm. It decreases the residue number by smoothing the couple residues in nearest distance. Then, the Goldstein algorithm is applied to link the other residues. As a result, a good solution is achieved. The experiment shows the validation of the algorithm in high-density residue condition.
A new unwrapping algorithm-Nearest Point Linking (NPL) algorithm is presented based on the Goldstein algorithm. It decreases the residue number by smoothing the couple residues in nearest distance. Then, the Goldstein algorithm is applied to link the other residues. As a result, a good solution is achieved. The experiment shows the validation of the algorithm in high-density residue condition.
2005, 27(2): 269-273.
Abstract:
The measured atmospheric model can only be represented as sum of spherical linear stratified models. Then the formula of apparent range of target is derived as sum of analytical expressions.When the initial elevation angle equals zero, therefore the accurate solution of apparent range of target can be obtained, It is indicated in this paper that effective earth radius can be introduced by using median value approximation of integration, which is also an effective technique to obtain accurate solution of atmospheric effects on radio wave propagation, Application of effective earth radius and methods to derive it are discussed.
The measured atmospheric model can only be represented as sum of spherical linear stratified models. Then the formula of apparent range of target is derived as sum of analytical expressions.When the initial elevation angle equals zero, therefore the accurate solution of apparent range of target can be obtained, It is indicated in this paper that effective earth radius can be introduced by using median value approximation of integration, which is also an effective technique to obtain accurate solution of atmospheric effects on radio wave propagation, Application of effective earth radius and methods to derive it are discussed.
2005, 27(2): 274-277.
Abstract:
A method of adaptive operating frequency selection for Over-The-Horizon Radar (OTHR), which can effectively improve the usage of spectrum resource in HF-band, is presented in this paper. A subarray with wide-band receiver is used to receive interference signals, and then the adaptive beamforming algorithm is applied to the signals separated by a few kilohertz. The frequency at which the array has the minimum output power is selected as the optimal operating frequency. Simulation results show that the method can effectively provide the optimal operating frequency for OTHR.
A method of adaptive operating frequency selection for Over-The-Horizon Radar (OTHR), which can effectively improve the usage of spectrum resource in HF-band, is presented in this paper. A subarray with wide-band receiver is used to receive interference signals, and then the adaptive beamforming algorithm is applied to the signals separated by a few kilohertz. The frequency at which the array has the minimum output power is selected as the optimal operating frequency. Simulation results show that the method can effectively provide the optimal operating frequency for OTHR.
2005, 27(2): 278-282.
Abstract:
The heavy loss of target detection performance must be resulted if the isolated interferers can not be effectively suppressed in the non-homogeneous environment of clutter. Therefore, a new method of two stage hybrid space time adaptive processing in non-homogeneous environment is presented in this paper, in which the homogeneous clutter is firstly suppressed based on auxiliary channel processing approach by selecting auxiliary channel according to clutters distributing characters in the beam Doppier space and the isolated interferers is latterly mitigated based on direct dnla domain algorithm, This method has advantages of excellent target detection performance, good robust to whether small yaw exists or not, and low computation load. Simulation results are presented to demonstrate its effectiveness,
The heavy loss of target detection performance must be resulted if the isolated interferers can not be effectively suppressed in the non-homogeneous environment of clutter. Therefore, a new method of two stage hybrid space time adaptive processing in non-homogeneous environment is presented in this paper, in which the homogeneous clutter is firstly suppressed based on auxiliary channel processing approach by selecting auxiliary channel according to clutters distributing characters in the beam Doppier space and the isolated interferers is latterly mitigated based on direct dnla domain algorithm, This method has advantages of excellent target detection performance, good robust to whether small yaw exists or not, and low computation load. Simulation results are presented to demonstrate its effectiveness,
The Study of Remote Sensing Images Matching Method Based on Wavelet Transform and Genetic Algorithms
2005, 27(2): 283-285.
Abstract:
In this paper, a matching method based on wavelet transform and genetic algorithms is proposed. First, the reference images and target images are decomposed to low resolution images using wavelet transform, Then, genetic algorithms, which are useful in finding global optima, are used to match the lowest resolution images. Based on the matching result, the matching between the higher resolution images can be implemented stepwise up to the full resolution images. The results confirm the proposed algorithm can improve the efficiency greatly while guarantee the accuracy.
In this paper, a matching method based on wavelet transform and genetic algorithms is proposed. First, the reference images and target images are decomposed to low resolution images using wavelet transform, Then, genetic algorithms, which are useful in finding global optima, are used to match the lowest resolution images. Based on the matching result, the matching between the higher resolution images can be implemented stepwise up to the full resolution images. The results confirm the proposed algorithm can improve the efficiency greatly while guarantee the accuracy.
2005, 27(2): 286-289.
Abstract:
Improved wavelet-domain HMT based remote-sensing image segmentation algorithm is proposed in this paper, The algorithm is based on 2-D directional wavelet, which is implemented via Hilbert transform pairs. The 2-D directional wavelet can provide both shift invariance and good directional selectivity. In this paper, the dependence of wavelet coefficients lied in inter scale is modeled efficiently, and a new segmentaion algorithm is produced by combining this with multicontext fusion method. A better segmentation result for remote-sensing image with smaller computational burden is obtained,
Improved wavelet-domain HMT based remote-sensing image segmentation algorithm is proposed in this paper, The algorithm is based on 2-D directional wavelet, which is implemented via Hilbert transform pairs. The 2-D directional wavelet can provide both shift invariance and good directional selectivity. In this paper, the dependence of wavelet coefficients lied in inter scale is modeled efficiently, and a new segmentaion algorithm is produced by combining this with multicontext fusion method. A better segmentation result for remote-sensing image with smaller computational burden is obtained,
2005, 27(2): 290-293.
Abstract:
The paper developes a novel nonlinear feature extraction method based on wavelet features. Its main idea is that wavelet transform is first employed to preprocess the original training images before the nonlinear mapping and three groups of wavelet features: lowest frequency subimage, horizontal detail and vertical detail, are derived respectively, What follows, Kernel Fisher Discriminant Analysis(KFDA) is performed on three classes of wavelet features. Three final discriminant feature vectors are obtained, from which a feature fusing method is developed. Finally, The experimental results on ORL face databases indicate that the proposed method is more effective than the current KFDA. And, more importantly, its consumed time in feature extraction is only one thirteenth of that of KFDA. Moreover, the experiments also demonstrate that this method is robust in uncontrolled lighting condition.
The paper developes a novel nonlinear feature extraction method based on wavelet features. Its main idea is that wavelet transform is first employed to preprocess the original training images before the nonlinear mapping and three groups of wavelet features: lowest frequency subimage, horizontal detail and vertical detail, are derived respectively, What follows, Kernel Fisher Discriminant Analysis(KFDA) is performed on three classes of wavelet features. Three final discriminant feature vectors are obtained, from which a feature fusing method is developed. Finally, The experimental results on ORL face databases indicate that the proposed method is more effective than the current KFDA. And, more importantly, its consumed time in feature extraction is only one thirteenth of that of KFDA. Moreover, the experiments also demonstrate that this method is robust in uncontrolled lighting condition.
2005, 27(2): 294-297.
Abstract:
Feature extraction is primary problem of pattern recognition. As one of the most classic methods in the field of feature extraction, Fisher linear discriminant analysis is applied widely. It may meet several possible problems in finding optimal set of discriminant vectors: the components of these vectors may not be real; the eigenvalue may be sensitive; these vectors may not be orthogonal each other. So the balanced scatter matrix is proposed in this paper. Based on the matrix, a discriminant criterion is formed. The optimal set of discriminant vectors can be acquired througn singular value decomposition theorem. The method can avoid the problems metioned above. The result of face recognition experiment shows that it has powerful ability of feature extraction.
Feature extraction is primary problem of pattern recognition. As one of the most classic methods in the field of feature extraction, Fisher linear discriminant analysis is applied widely. It may meet several possible problems in finding optimal set of discriminant vectors: the components of these vectors may not be real; the eigenvalue may be sensitive; these vectors may not be orthogonal each other. So the balanced scatter matrix is proposed in this paper. Based on the matrix, a discriminant criterion is formed. The optimal set of discriminant vectors can be acquired througn singular value decomposition theorem. The method can avoid the problems metioned above. The result of face recognition experiment shows that it has powerful ability of feature extraction.
2005, 27(2): 298-301.
Abstract:
A novel algorithm for rapid surface interpolation from massive scattered data using Compactly Supported Radial Basis Functions (CSRBF) and conjugate gradient method is presented in this paper, CSRBF is used because it can make the coefficient equations symmetric positive definite (spd), and very sparse. So there must be a solver and a smat 1 storage memory are needed. In solving the system equations, iterative method is used. The conjugate gradient method is used to solve the system equations, because the method converges in at most N steps for a symmetric positive definite N by TV matrix. Experimental results using massive scattered points demonstrate the algorithm is fast. The proposed algorithm is very appropriate for surface interpolation from massive scattered points.
A novel algorithm for rapid surface interpolation from massive scattered data using Compactly Supported Radial Basis Functions (CSRBF) and conjugate gradient method is presented in this paper, CSRBF is used because it can make the coefficient equations symmetric positive definite (spd), and very sparse. So there must be a solver and a smat 1 storage memory are needed. In solving the system equations, iterative method is used. The conjugate gradient method is used to solve the system equations, because the method converges in at most N steps for a symmetric positive definite N by TV matrix. Experimental results using massive scattered points demonstrate the algorithm is fast. The proposed algorithm is very appropriate for surface interpolation from massive scattered points.
2005, 27(2): 302-305.
Abstract:
In cluster analysis, Fuzzy K-Means (FKM) algorithm is one of the most widely used methods. However, FKM algorithm is much more sensitive to the initialization, and easy to fall into local optimum. For this purpose, this paper presents a clonal selection based new algorithm for fuzzy clustering analysis, for global optimization. Since the clonal operator can combine the evolutionary search and random search, and incorporate the global search with local search, by the clonal operation on candidate solutions, the new algorithm can quickly obtain the global optimum. The experimental results with synthetic data and IRIS real data illustrate the effectiveness of the new algorithm.
In cluster analysis, Fuzzy K-Means (FKM) algorithm is one of the most widely used methods. However, FKM algorithm is much more sensitive to the initialization, and easy to fall into local optimum. For this purpose, this paper presents a clonal selection based new algorithm for fuzzy clustering analysis, for global optimization. Since the clonal operator can combine the evolutionary search and random search, and incorporate the global search with local search, by the clonal operation on candidate solutions, the new algorithm can quickly obtain the global optimum. The experimental results with synthetic data and IRIS real data illustrate the effectiveness of the new algorithm.
2005, 27(2): 306-309.
Abstract:
On the basis of studying some recent motion contours detection algorithms, a new approach to extract contours of moving objects from three consecutive image frames with complex background is suggested in this paper. Several experiments show that the algorithm is robust in noisy environment, effective to reduce the effect of objects shadow and occluding, and efficient for moving objects contours detection among image sequence with complex background.
On the basis of studying some recent motion contours detection algorithms, a new approach to extract contours of moving objects from three consecutive image frames with complex background is suggested in this paper. Several experiments show that the algorithm is robust in noisy environment, effective to reduce the effect of objects shadow and occluding, and efficient for moving objects contours detection among image sequence with complex background.
2005, 27(2): 310-313.
Abstract:
In a distributed multisensor system, the problem of track correlation can be transformed into the problem of multi-dimension assignment. The problem of multi-dimension assignment is a typical combined optimization problem, it is very hard to find its optimum solution and its computing burden increases heavily with the increase of dimensions and the number of targets. So a new model of three-dimension neural network is proposed in this paper to deal with the problem of three-dimension assignment. The experimental results illustrate that this model can effectively solve the problem of track correlation and have higher correct association percent. And the model of three-dimension neural network proposed in this paper can be generalized to multi-dimension model to solve the problem of multi-dimension assignment.
In a distributed multisensor system, the problem of track correlation can be transformed into the problem of multi-dimension assignment. The problem of multi-dimension assignment is a typical combined optimization problem, it is very hard to find its optimum solution and its computing burden increases heavily with the increase of dimensions and the number of targets. So a new model of three-dimension neural network is proposed in this paper to deal with the problem of three-dimension assignment. The experimental results illustrate that this model can effectively solve the problem of track correlation and have higher correct association percent. And the model of three-dimension neural network proposed in this paper can be generalized to multi-dimension model to solve the problem of multi-dimension assignment.
2005, 27(2): 314-316.
Abstract:
A PKI system based on XKMS, which can provide XKMS-based PKI services, is introduced in this paper. This paper also describes the system design, developing environment in more details. The running instances, testing and analysis of this system are also given. By testing and analysis, it indicates that the system has the properties of high efficiency, cross-platform, and good portability.
A PKI system based on XKMS, which can provide XKMS-based PKI services, is introduced in this paper. This paper also describes the system design, developing environment in more details. The running instances, testing and analysis of this system are also given. By testing and analysis, it indicates that the system has the properties of high efficiency, cross-platform, and good portability.
2005, 27(2): 317-321.
Abstract:
This paper presents a hardware-software co-verification method for SOC design, which is based on instruction set simulator and hardware simulator, and used to validate function of SOC in the early design phase. The generating and processing methods of interactive events between hardware and software simulator during co-simulation are discussed in detail. An algorithm of synchronizing between hardware and software simulator is presented, and to reduce the synchronization overhead, some optimizing methods are introduced. Finally, an co-verification example of a design based on ARM7TDMI is given.
This paper presents a hardware-software co-verification method for SOC design, which is based on instruction set simulator and hardware simulator, and used to validate function of SOC in the early design phase. The generating and processing methods of interactive events between hardware and software simulator during co-simulation are discussed in detail. An algorithm of synchronizing between hardware and software simulator is presented, and to reduce the synchronization overhead, some optimizing methods are introduced. Finally, an co-verification example of a design based on ARM7TDMI is given.
2005, 27(2): 322-325.
Abstract:
A threshold voltage model of the short channel DMOS (Double-Diffusion Metal-Oxide- Semiconductor) is proposed. Based on the 2-D distribution of channel depletion charge, the channel depletion charge is calculated and the mathematical expression of the threshold voltage model of the short channel DMOS is obtained. The results of the model agree well with those of the 2-D simulator MEDICI. The analysis shows that the effect of short channel should be considered when the channel length is less than 0.80m.
A threshold voltage model of the short channel DMOS (Double-Diffusion Metal-Oxide- Semiconductor) is proposed. Based on the 2-D distribution of channel depletion charge, the channel depletion charge is calculated and the mathematical expression of the threshold voltage model of the short channel DMOS is obtained. The results of the model agree well with those of the 2-D simulator MEDICI. The analysis shows that the effect of short channel should be considered when the channel length is less than 0.80m.
2005, 27(2): 326-328.
Abstract:
A combined, unsupervised, multilayer perceptron neural network model based on MISEP and NLFA is presented to resolve the separation problem of nonlinear ICA, the separation performances of signals are compared between two sigmoid functions used in the latent layers of MISEP and introduced RBF. Experimental results show this algorithm can recover sources from nonlinear mixtures better and has good stabilization, it is also applied to single-trial extraction of SCP, the whole effect is evident compared with the averaged method.
A combined, unsupervised, multilayer perceptron neural network model based on MISEP and NLFA is presented to resolve the separation problem of nonlinear ICA, the separation performances of signals are compared between two sigmoid functions used in the latent layers of MISEP and introduced RBF. Experimental results show this algorithm can recover sources from nonlinear mixtures better and has good stabilization, it is also applied to single-trial extraction of SCP, the whole effect is evident compared with the averaged method.
2005, 27(2): 329-331.
Abstract:
A new type cumulant-based virtual DOA matrix is formed using the property of aperture extension of fourth-order cumulants. The azimuth and elevation of the incident sources can be estimated simultaneity from the amplitude and phase information of non-zero eigenvalue of the new matrix respectively. With arbitrary geometry of the array, this method can extend actual array aperture efficiently. By properly laying out the array, this algorithm can suppress arbitrary distributed background noise and better estimation of DOA can be obtained.
A new type cumulant-based virtual DOA matrix is formed using the property of aperture extension of fourth-order cumulants. The azimuth and elevation of the incident sources can be estimated simultaneity from the amplitude and phase information of non-zero eigenvalue of the new matrix respectively. With arbitrary geometry of the array, this method can extend actual array aperture efficiently. By properly laying out the array, this algorithm can suppress arbitrary distributed background noise and better estimation of DOA can be obtained.
2005, 27(2): 332-333.
Abstract:
High accuracy moving target detection is a key technique in the digital radar receiver. The Doppler frequency estimation methods which have been presented can not satisfy the performances of modern digital receivers such as high estimation accuracy, less computation, super low SNR circumstance, etc. In this paper, a high accuracy detection technique of moving target based on double sample rate in low SNR circumstance is proposed, and it includes three main techniques, i.e. unambiguous frequency estimation of sub-sampling signal based on FFT, high accuracy Doppler frequency estimation and radial rate estimation of moving target based on double sample rate.
High accuracy moving target detection is a key technique in the digital radar receiver. The Doppler frequency estimation methods which have been presented can not satisfy the performances of modern digital receivers such as high estimation accuracy, less computation, super low SNR circumstance, etc. In this paper, a high accuracy detection technique of moving target based on double sample rate in low SNR circumstance is proposed, and it includes three main techniques, i.e. unambiguous frequency estimation of sub-sampling signal based on FFT, high accuracy Doppler frequency estimation and radial rate estimation of moving target based on double sample rate.
2005, 27(2): 334-336.
Abstract:
Taking the latch composed of two inverters as basic storage unit, this paper proposes a novel CMOS JK flip-flop based on the design at switch level. The new design has simpler configuration with less devices and faster working speed in comparing with the traditional design.
Taking the latch composed of two inverters as basic storage unit, this paper proposes a novel CMOS JK flip-flop based on the design at switch level. The new design has simpler configuration with less devices and faster working speed in comparing with the traditional design.
