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2005 Vol. 27, No. 5
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2005, 27(5): 673-678.
Abstract:
The combining form of the MultiCarrier (MC) technique with the Vertical Bell Labs lAyered Space-Time (V-BLAST) architecture, i.e., the MC V-BLAST system, can better take advantage of the frequency diversity force resulting from the frequency-selective feature in the broadband mobile wireless multimedia communications. This paper explores the decoding problem of the MC V-BLAST system under the downlink frequency-selective fading environment. One novel shift-invariance coding scheme is firstly proposed for the MC V-BLAST system. Successively, by exploiting the above shift-invariance property, a decoding algorithm without knowing Channel State Information (CSI) is derived. Simulations demonstrate the validity of the novel shift-invariance coding scheme and the performance of the decoding algorithm.
The combining form of the MultiCarrier (MC) technique with the Vertical Bell Labs lAyered Space-Time (V-BLAST) architecture, i.e., the MC V-BLAST system, can better take advantage of the frequency diversity force resulting from the frequency-selective feature in the broadband mobile wireless multimedia communications. This paper explores the decoding problem of the MC V-BLAST system under the downlink frequency-selective fading environment. One novel shift-invariance coding scheme is firstly proposed for the MC V-BLAST system. Successively, by exploiting the above shift-invariance property, a decoding algorithm without knowing Channel State Information (CSI) is derived. Simulations demonstrate the validity of the novel shift-invariance coding scheme and the performance of the decoding algorithm.
2005, 27(5): 679-682.
Abstract:
The proposed Grade of Service based Call Admission Control (GoS-CAC) algorithm operates a threshold comparison, which integrates many factors that affect the decision accuracy of a CAC scheme such as system traffic loads, Quality of Service (QoS) requirements, channel quality, interference level, system GoS and user handoff, etc. The GoS-CAC algorithm cooperates subtly with a power/data rate adjustment scheme making able fast, accurate, adaptive threshold, simple and feasible decision-making about incoming calls. Simulation results show that the proposed algorithm outperforms traditional CAC schemes about 10%, 50% and above 57% in terms of handoff service blocking probability, system GoS and overall system dropping probability, respectively.
The proposed Grade of Service based Call Admission Control (GoS-CAC) algorithm operates a threshold comparison, which integrates many factors that affect the decision accuracy of a CAC scheme such as system traffic loads, Quality of Service (QoS) requirements, channel quality, interference level, system GoS and user handoff, etc. The GoS-CAC algorithm cooperates subtly with a power/data rate adjustment scheme making able fast, accurate, adaptive threshold, simple and feasible decision-making about incoming calls. Simulation results show that the proposed algorithm outperforms traditional CAC schemes about 10%, 50% and above 57% in terms of handoff service blocking probability, system GoS and overall system dropping probability, respectively.
2005, 27(5): 683-687.
Abstract:
OFDM systems is sensitive to the frequency offset. In this paper, a novel frequency ambiguity resolution algorithm in OFDM systems based on null subcarrier detection is proposed to correct the frequency ambiguity. It utilizes the subcarriers which transmit no information bit to correct the frequency ambiguity. In the paper, the effect of timing error on the performance of proposed algorithm is analyzed and the computational complexity of the proposed algorithm is compared with that of conventional algorithm. Simulation results show that the proposed algorithm has the low complexity advantage over conventional algorithm while maintain the same performance.
OFDM systems is sensitive to the frequency offset. In this paper, a novel frequency ambiguity resolution algorithm in OFDM systems based on null subcarrier detection is proposed to correct the frequency ambiguity. It utilizes the subcarriers which transmit no information bit to correct the frequency ambiguity. In the paper, the effect of timing error on the performance of proposed algorithm is analyzed and the computational complexity of the proposed algorithm is compared with that of conventional algorithm. Simulation results show that the proposed algorithm has the low complexity advantage over conventional algorithm while maintain the same performance.
2005, 27(5): 688-690.
Abstract:
A new OFDM decision-directed carrier frequency offset tracking algorithm is presented. High precision, low computational efforts and simple implement are obtained with the new algorithm. And an improvement method is also described which enhances the capacity of resist frequency selected fading channel, based on channel information. With this method, the tracking performance at low SNR is improved.
A new OFDM decision-directed carrier frequency offset tracking algorithm is presented. High precision, low computational efforts and simple implement are obtained with the new algorithm. And an improvement method is also described which enhances the capacity of resist frequency selected fading channel, based on channel information. With this method, the tracking performance at low SNR is improved.
2005, 27(5): 691-693.
Abstract:
Avoiding oscillation phenomenon which occurs in analysis and reconstruction of image edges, an application without extrapolation both sides is proposed. Image energy is concentrated in low frequency by using nonlinear transform, and the exact jumps location are detected by local maximum of wavelet transform in fine scale. Non-oscillation edges of reconstructed image are received with less storage space and computing time.
Avoiding oscillation phenomenon which occurs in analysis and reconstruction of image edges, an application without extrapolation both sides is proposed. Image energy is concentrated in low frequency by using nonlinear transform, and the exact jumps location are detected by local maximum of wavelet transform in fine scale. Non-oscillation edges of reconstructed image are received with less storage space and computing time.
2005, 27(5): 694-698.
Abstract:
In this paper, on the basis of analyzing the principle of Multi-Carrier Code Division Multiple Access (MC-CDMA) technique, by adopting the optimized multiband complex wavelet as multi-carrier modulation and the turbo codes as channel coding, a MC-CDMA system based on optimized multiband complex wavelet and turbo coding is proposed, and the system bit error rate performance is investigated in Rayleigh fading channel. The system can overcome the decrease of efficiency of spectrum and energy of conventional MC-CDMA due to inserting Cyclic Prefix (CP); and make full use of the turbo codes good capacity against fading channel to improve the system performance further. Theoretical analysis and simulation results all show that the proposed system outperforms conventional MC-CDMA system, and the performance of the system is superior to that of the conventional MC-CDMA with CP. Meanwhile, the application of turbo coding strengthens the system ability to cope with multi-path fading and Multi-Access Interference (MAI) significantly.
In this paper, on the basis of analyzing the principle of Multi-Carrier Code Division Multiple Access (MC-CDMA) technique, by adopting the optimized multiband complex wavelet as multi-carrier modulation and the turbo codes as channel coding, a MC-CDMA system based on optimized multiband complex wavelet and turbo coding is proposed, and the system bit error rate performance is investigated in Rayleigh fading channel. The system can overcome the decrease of efficiency of spectrum and energy of conventional MC-CDMA due to inserting Cyclic Prefix (CP); and make full use of the turbo codes good capacity against fading channel to improve the system performance further. Theoretical analysis and simulation results all show that the proposed system outperforms conventional MC-CDMA system, and the performance of the system is superior to that of the conventional MC-CDMA with CP. Meanwhile, the application of turbo coding strengthens the system ability to cope with multi-path fading and Multi-Access Interference (MAI) significantly.
2005, 27(5): 699-702.
Abstract:
In this paper, a new generalized construction method for correlation immune Boolean function satisfying PC(l) of order k is provided. The construction is based on the use of linear error-correcting codes together with bijective functions. Furthermore, some new construction methods for (n , m , t) resilient functions satisfying PC(l) of order k is also discussed. In addition, the authors also show that these functions have many other good cryptographic properties such as high nonlinearity, good algebraic degree and so on .
In this paper, a new generalized construction method for correlation immune Boolean function satisfying PC(l) of order k is provided. The construction is based on the use of linear error-correcting codes together with bijective functions. Furthermore, some new construction methods for (n , m , t) resilient functions satisfying PC(l) of order k is also discussed. In addition, the authors also show that these functions have many other good cryptographic properties such as high nonlinearity, good algebraic degree and so on .
2005, 27(5): 703-706.
Abstract:
Chaos shift keying secure communication system with dual-ring erbium-doped fiber laser is presented. The chaos shift keying is realized by modulating parameters of the pump light. A matching method to reduce the synchronization error by modulating the parameters to compensate the system parameter mismatches is numerically studied. Chaotic synchronizations and decoding at 0 and 1 bit, respectively, are numerically simulated between two single-ring erbium-doped fiber lasers and a dual-ring single-mode erbium-doped fiber lasers. The system shows the good ability of robust security and anti-uncoverage in phase-space, time-domain and frequency-domain.
Chaos shift keying secure communication system with dual-ring erbium-doped fiber laser is presented. The chaos shift keying is realized by modulating parameters of the pump light. A matching method to reduce the synchronization error by modulating the parameters to compensate the system parameter mismatches is numerically studied. Chaotic synchronizations and decoding at 0 and 1 bit, respectively, are numerically simulated between two single-ring erbium-doped fiber lasers and a dual-ring single-mode erbium-doped fiber lasers. The system shows the good ability of robust security and anti-uncoverage in phase-space, time-domain and frequency-domain.
2005, 27(5): 707-711.
Abstract:
The paper investigates the QoS routing problem with uncertain network condition, including MP(Most Probable Path), OP(Optimal Partition) and OP-MP(Optimally Partitioned MP). The question MP is studied when density function of the link delay is continuous and an algorithm for a special case that the link delay has normal distribution is proposed. For question OP and OP-MP, two cases of QoS partition are given: Case I optimizes the product of the probability that all the links of the path satisfy the partitioned constraints, while the case II maximizes the minimum of them. The two cases are analyzed and the algorithms are given.
The paper investigates the QoS routing problem with uncertain network condition, including MP(Most Probable Path), OP(Optimal Partition) and OP-MP(Optimally Partitioned MP). The question MP is studied when density function of the link delay is continuous and an algorithm for a special case that the link delay has normal distribution is proposed. For question OP and OP-MP, two cases of QoS partition are given: Case I optimizes the product of the probability that all the links of the path satisfy the partitioned constraints, while the case II maximizes the minimum of them. The two cases are analyzed and the algorithms are given.
2005, 27(5): 712-716.
Abstract:
This paper proposes a class of convolutional codes based on complementary structure to cancel the First-Adjacent Channel(FAC) interference in FM In-band On-channel Digital Audio Broadcasting(FM IBOC DAB) system. Those complementary convolutional codes, which are transmitted by frequency diversity scheme, can effectively deal with the problem in situations where the transmitted data may be lost or severely damaged. The simulation results and analysis show that complementary codes combining scheme yields a better result of 1-2 dB asymptotic code gain than identical codes combining scheme.
This paper proposes a class of convolutional codes based on complementary structure to cancel the First-Adjacent Channel(FAC) interference in FM In-band On-channel Digital Audio Broadcasting(FM IBOC DAB) system. Those complementary convolutional codes, which are transmitted by frequency diversity scheme, can effectively deal with the problem in situations where the transmitted data may be lost or severely damaged. The simulation results and analysis show that complementary codes combining scheme yields a better result of 1-2 dB asymptotic code gain than identical codes combining scheme.
2005, 27(5): 717-721.
Abstract:
In this paper, the image intensity surface for the neighborhood of every pixel is well-fitted by the Least Squares Support Vector Machine (LSSVM), and the gradient and the zero-crossing operators are deduced from the LSSVM with the Radial Basis Function (RBF) kernel function, as an example. The decision is made whether a pixel is an edge or not based on the combination results of the gradient and the zero-crossings. One method using the edge detection evaluating merit figure to optimize the LSSVM parameters is proposed. The optimal configuration of parameters (2,) for the LSSVM with RBF kernel is (7, 1). With the selected parameters, the computer edge detection experiments are carried out. The experimental results demonstrate the proposed algorithm is reliable and efficient.
In this paper, the image intensity surface for the neighborhood of every pixel is well-fitted by the Least Squares Support Vector Machine (LSSVM), and the gradient and the zero-crossing operators are deduced from the LSSVM with the Radial Basis Function (RBF) kernel function, as an example. The decision is made whether a pixel is an edge or not based on the combination results of the gradient and the zero-crossings. One method using the edge detection evaluating merit figure to optimize the LSSVM parameters is proposed. The optimal configuration of parameters (2,) for the LSSVM with RBF kernel is (7, 1). With the selected parameters, the computer edge detection experiments are carried out. The experimental results demonstrate the proposed algorithm is reliable and efficient.
2005, 27(5): 722-725.
Abstract:
This paper is mainly about the theoretical method to analyzing the frame error rate of Rate Compatable Punctured Turbo (RCPT) codes and the throughput efficiency of the RCPT-ARQ system. The time-varying trellis method is proposed to calculate the input-output weight enumerating function of RCPT codes. Based on the Sasons tight bound, the upper bound of frame error rate of RCPT codes is achieved. Then the performance bound of the RCPT-ARQ system can be calculated. The theoretical results show great consistence with the simulation results.
This paper is mainly about the theoretical method to analyzing the frame error rate of Rate Compatable Punctured Turbo (RCPT) codes and the throughput efficiency of the RCPT-ARQ system. The time-varying trellis method is proposed to calculate the input-output weight enumerating function of RCPT codes. Based on the Sasons tight bound, the upper bound of frame error rate of RCPT codes is achieved. Then the performance bound of the RCPT-ARQ system can be calculated. The theoretical results show great consistence with the simulation results.
2005, 27(5): 726-730.
Abstract:
A new spatial time-frequency distribution of polarization is constructed using fractional Fourier Transform for LFM signals, A novel algorithm of joint two-dimensional and polarization estimation is proposed based on the vector sensor array of L mode. Theoretical analysis and computer simulation demonstrate the efficacy in the lower signal noise rate.
A new spatial time-frequency distribution of polarization is constructed using fractional Fourier Transform for LFM signals, A novel algorithm of joint two-dimensional and polarization estimation is proposed based on the vector sensor array of L mode. Theoretical analysis and computer simulation demonstrate the efficacy in the lower signal noise rate.
2005, 27(5): 731-733.
Abstract:
As for a large number of unknown frequencies of harmonic signals existing in the practice, the paper presents the detecting method utilizing the nonlinear chaotic dynamic system. Firstly, the method verifies being the periodic solution originated from the nonlinear equation theory, then founds the simulating model to calculate harmonic frequency using directional crossover technique. The technique is feasible through analyzing the absolute error and relative error of calculating results. At the same time, the paper brings forward the possibility to further detecting harmonic amplitude after detecting frequency.
As for a large number of unknown frequencies of harmonic signals existing in the practice, the paper presents the detecting method utilizing the nonlinear chaotic dynamic system. Firstly, the method verifies being the periodic solution originated from the nonlinear equation theory, then founds the simulating model to calculate harmonic frequency using directional crossover technique. The technique is feasible through analyzing the absolute error and relative error of calculating results. At the same time, the paper brings forward the possibility to further detecting harmonic amplitude after detecting frequency.
2005, 27(5): 734-739.
Abstract:
For small parameter Stochastic Resonance (SR), the relationship among the response amplitude and signal frequency and noise intensity is investigated. The viewpoint of creating SR phenomenon only in the low frequency region where noise energy has been concentrated is also obtained in terms of the Lorentzian distribution of noise power spectrum. The condition of realizing twice sampling large parameter SR-like phenomenon is deduced, i.e., sampling frequency is fifty times signal frequency at least, and twice sampling frequency should be selected according to noise strength. Under large parameters, the analysis of input and output signal-to-ratios of the bistable system indicates the possibility of detecting weak signal submerged in heavy noise with the large parameter SR-like technique. And it is further proved that the technique is effective and practical by means of the examples of the extraction of periodic and aperiodic signals.
For small parameter Stochastic Resonance (SR), the relationship among the response amplitude and signal frequency and noise intensity is investigated. The viewpoint of creating SR phenomenon only in the low frequency region where noise energy has been concentrated is also obtained in terms of the Lorentzian distribution of noise power spectrum. The condition of realizing twice sampling large parameter SR-like phenomenon is deduced, i.e., sampling frequency is fifty times signal frequency at least, and twice sampling frequency should be selected according to noise strength. Under large parameters, the analysis of input and output signal-to-ratios of the bistable system indicates the possibility of detecting weak signal submerged in heavy noise with the large parameter SR-like technique. And it is further proved that the technique is effective and practical by means of the examples of the extraction of periodic and aperiodic signals.
2005, 27(5): 740-744.
Abstract:
The Adaptive Fractional Lower order Covariance (AFLC) time delay estimation method performs robust under impulsive noise environments, but the values of parameters a and b have effects on estimated precision. According to the non-stationary property of noises, this paper proposes a dynamic parameter estimation method and further proposes a Modified Adaptive Fractional Lower order Covariance (M-AFLC) method. Computer simulation indicates that the iterative parameter estimation method performs well under both stationaiy and non-stationary noise conditions. It also shows that the M-AFLC maintains the merits of the AFLC, and at the same time the proposed method avoids the degradation of AFLC while the restriction unsatisfied.
The Adaptive Fractional Lower order Covariance (AFLC) time delay estimation method performs robust under impulsive noise environments, but the values of parameters a and b have effects on estimated precision. According to the non-stationary property of noises, this paper proposes a dynamic parameter estimation method and further proposes a Modified Adaptive Fractional Lower order Covariance (M-AFLC) method. Computer simulation indicates that the iterative parameter estimation method performs well under both stationaiy and non-stationary noise conditions. It also shows that the M-AFLC maintains the merits of the AFLC, and at the same time the proposed method avoids the degradation of AFLC while the restriction unsatisfied.
2005, 27(5): 745-748.
Abstract:
To achieve good performance when applying subspace method based on four-order cumulants in DOA estimation, signals are required to be independent to satisfy non-coherence of four-order. Here, a modified method without independence requirement is proposed. First, the relation between non-coherence of four-order and carrier frequencies of analytical signal is studied with baseband signals independent or not, then a set of small frequencies offset is designed. With the transmitter modulating signals in baseband with the frequencies, the array receiver can achieve good performance of DOA estimation with subspace method based on four-order cumulants whether signals are independent or not. Simulation proves its validity.
To achieve good performance when applying subspace method based on four-order cumulants in DOA estimation, signals are required to be independent to satisfy non-coherence of four-order. Here, a modified method without independence requirement is proposed. First, the relation between non-coherence of four-order and carrier frequencies of analytical signal is studied with baseband signals independent or not, then a set of small frequencies offset is designed. With the transmitter modulating signals in baseband with the frequencies, the array receiver can achieve good performance of DOA estimation with subspace method based on four-order cumulants whether signals are independent or not. Simulation proves its validity.
2005, 27(5): 749-752.
Abstract:
The rank-1 ambiguity problem involved in the Polarization-Angular Coherence Structure (PACS) of a 5-D co-localized vector antenna whose elements are orthogonally oriented is adrressed in this paper. Two kinds of equivalent relations are defined, under which several typical and easy-analyzed 5-D PACSs are studied. It is further shown in the paper that with only one 5-D vector antenna, DOA and polarization of one signal except for the case of horizontally polarized signal could be uniquely identified, as is done by the well-known 6-D ElectroMagnetic (EM) vector sensor. Some representative examples are also given to validate the present analyses.
The rank-1 ambiguity problem involved in the Polarization-Angular Coherence Structure (PACS) of a 5-D co-localized vector antenna whose elements are orthogonally oriented is adrressed in this paper. Two kinds of equivalent relations are defined, under which several typical and easy-analyzed 5-D PACSs are studied. It is further shown in the paper that with only one 5-D vector antenna, DOA and polarization of one signal except for the case of horizontally polarized signal could be uniquely identified, as is done by the well-known 6-D ElectroMagnetic (EM) vector sensor. Some representative examples are also given to validate the present analyses.
2005, 27(5): 757-761.
Abstract:
This paper describes a novel motion object detection and tracking algorithm based on the Multiscale Edges Detection (MED) and Continuous Wavelet Transform (CWT). Multiscale representations are very effective for analyzing the information content of images. First, moving object multiscale edges are detected and characterized from the local maxima of a wavelet transform. Then, the CWT is used to map the input signal space to a motion parameters space. It is designed so as to possess simultaneously the properties of MED and CWT. Experimental results show that the proposed algorithm is effective with robustness for noise, rotation and occlusions.
This paper describes a novel motion object detection and tracking algorithm based on the Multiscale Edges Detection (MED) and Continuous Wavelet Transform (CWT). Multiscale representations are very effective for analyzing the information content of images. First, moving object multiscale edges are detected and characterized from the local maxima of a wavelet transform. Then, the CWT is used to map the input signal space to a motion parameters space. It is designed so as to possess simultaneously the properties of MED and CWT. Experimental results show that the proposed algorithm is effective with robustness for noise, rotation and occlusions.
2005, 27(5): 762-766.
Abstract:
With lots of studies, it is admitted that the variable bit rate video traffic exhibits high long range dependence and burstness. Its traffic is predicted by auto-regressive process with high order in this paper while the probablity distribution of traffic predicted is also transformed to that of real situation. And then a new dynamic bandwidth allocation algorithm named hysteresis algorithm is presented, by which performances of buffer size requirement and cell loss rate are both improved significantly compared with threshold algorithm presented by Chiruvolu (1998) and allocation scheme based on group of pirclures scene detection presented by Iraqi (1999). The proposed algorithm gives attention to both cell loss rate and utilization at the considerate low cost (reallocation frequency ^2%) according to a number of simulations. And the bandwidth reallocation process is only triggered when the queuing length of buffer surpasses the roundabout threshold so that it is easy for online realization.
With lots of studies, it is admitted that the variable bit rate video traffic exhibits high long range dependence and burstness. Its traffic is predicted by auto-regressive process with high order in this paper while the probablity distribution of traffic predicted is also transformed to that of real situation. And then a new dynamic bandwidth allocation algorithm named hysteresis algorithm is presented, by which performances of buffer size requirement and cell loss rate are both improved significantly compared with threshold algorithm presented by Chiruvolu (1998) and allocation scheme based on group of pirclures scene detection presented by Iraqi (1999). The proposed algorithm gives attention to both cell loss rate and utilization at the considerate low cost (reallocation frequency ^2%) according to a number of simulations. And the bandwidth reallocation process is only triggered when the queuing length of buffer surpasses the roundabout threshold so that it is easy for online realization.
2005, 27(5): 767-770.
Abstract:
With the fast development and extensive application of Synthetic Aperture Radar(SAR), There are more and more interference and jamming to SAR. It is necessary to assure performance of SAR imaging to enhance the ability of interference suppression. This paper analyzes the characteristics of the common Narrow Band Interference (NBI). A new approach for NBI suppression is proposed, which uses eigen-subspace based filtering on the echo data of SAR. Simulation results of SAR show that the proposed approach can suppress the NBI effectively.
With the fast development and extensive application of Synthetic Aperture Radar(SAR), There are more and more interference and jamming to SAR. It is necessary to assure performance of SAR imaging to enhance the ability of interference suppression. This paper analyzes the characteristics of the common Narrow Band Interference (NBI). A new approach for NBI suppression is proposed, which uses eigen-subspace based filtering on the echo data of SAR. Simulation results of SAR show that the proposed approach can suppress the NBI effectively.
2005, 27(5): 771-774.
Abstract:
Under the given condition, distributed small satellites bistatic SAR can be considered as a kind of bistatic SAR, whose transmitter and receiver move in parallel. In this paper, an imaging method based on range distance compensation is discussed. With this method the phase of distributed small satellites bistatic SAR can be expressed in the form of monostatic SAR. Therefore, the monostatic SAR imaging algorithms can be used to process the data obtained from bistatic SAR system. To illuminate this method better, wavenumber-domain algorithm has been used. Simulation result is also provided here, it shows that this method can be effectively used in distributed small satellites bistatic SAR imaging system.
Under the given condition, distributed small satellites bistatic SAR can be considered as a kind of bistatic SAR, whose transmitter and receiver move in parallel. In this paper, an imaging method based on range distance compensation is discussed. With this method the phase of distributed small satellites bistatic SAR can be expressed in the form of monostatic SAR. Therefore, the monostatic SAR imaging algorithms can be used to process the data obtained from bistatic SAR system. To illuminate this method better, wavenumber-domain algorithm has been used. Simulation result is also provided here, it shows that this method can be effectively used in distributed small satellites bistatic SAR imaging system.
2005, 27(5): 775-778.
Abstract:
Taking Rayleigh model as an example, this paper studies a correction method for Synthetic Aperture Radar (SAR) analog-to-digital converter saturation based on power compensation and extends it to Weibull model. Then it analyzes the applicability of the Weibull model correction method and verifies it by the Radarsat SAR data.
Taking Rayleigh model as an example, this paper studies a correction method for Synthetic Aperture Radar (SAR) analog-to-digital converter saturation based on power compensation and extends it to Weibull model. Then it analyzes the applicability of the Weibull model correction method and verifies it by the Radarsat SAR data.
2005, 27(5): 779-783.
Abstract:
In this paper a new algorithm for SAR image lossy compression based on lifting scheme is brought forward, aiming at special characteristics of SAR imagery. The algorithm can reduce the speckle noise, improve the computation precision and time, and upswing the compression ability. The algorithm adopts embedded zerotree wavelets, making good use of the wavelet coefficients .Large numbers of SAR images validate the efficiency of the proposed algorithm.The results compare favorably with that of other image compression methods.
In this paper a new algorithm for SAR image lossy compression based on lifting scheme is brought forward, aiming at special characteristics of SAR imagery. The algorithm can reduce the speckle noise, improve the computation precision and time, and upswing the compression ability. The algorithm adopts embedded zerotree wavelets, making good use of the wavelet coefficients .Large numbers of SAR images validate the efficiency of the proposed algorithm.The results compare favorably with that of other image compression methods.
2005, 27(5): 784-788.
Abstract:
In this paper, one-dimensional scattering centre extraction of radar targets is reviewed. A new classifier based on fuzzy distribution is proposed, which is very much suitable for one-dimensional scattering centre classification. The fuzzy classifier does not require the feature vectors to have the same dimension and allows the training samples to be flexibly chosen for different test samples. Theoretical analysis and simulation results show that the proposed fuzzy classifier can efficiently solve the problem of radar target recognition using one-dimensional scattering centres.
In this paper, one-dimensional scattering centre extraction of radar targets is reviewed. A new classifier based on fuzzy distribution is proposed, which is very much suitable for one-dimensional scattering centre classification. The fuzzy classifier does not require the feature vectors to have the same dimension and allows the training samples to be flexibly chosen for different test samples. Theoretical analysis and simulation results show that the proposed fuzzy classifier can efficiently solve the problem of radar target recognition using one-dimensional scattering centres.
2005, 27(5): 789-792.
Abstract:
This paper analyses the limitation of the algorithm of stagger multiple frequency for CW radar, and two algorithms are proposed.They are the algorithm of multiple frequency to dual frequency and the algorithm of quadratic phase difference.Their principles are introduced. Finally, two algorithm are compared with each other, simulation result is also given.The simulation result shows that two algorithms both reach high ranging accuracy.They have equivalent ranging accuracy if their maximal unambiguous ranges of the last dual frequency are the same.
This paper analyses the limitation of the algorithm of stagger multiple frequency for CW radar, and two algorithms are proposed.They are the algorithm of multiple frequency to dual frequency and the algorithm of quadratic phase difference.Their principles are introduced. Finally, two algorithm are compared with each other, simulation result is also given.The simulation result shows that two algorithms both reach high ranging accuracy.They have equivalent ranging accuracy if their maximal unambiguous ranges of the last dual frequency are the same.
2005, 27(5): 793-796.
Abstract:
To avoid the computational complexity and the precision decrease from the nonlinear feature in passive tracking, the state of the target is approximately estimated by least squares algorithm at first, and then a current statistical model and an adaptive algorithm are employed. The simulation results show that the novel least squares adaptive algorithm is of higher tracking precision than Singer algorithm in tracking the target with constant velocity or acceleration, and that it is able to estimate effectively the velocity and acceleration of the maneuvering target, in which case Singer algorithm does not work.
To avoid the computational complexity and the precision decrease from the nonlinear feature in passive tracking, the state of the target is approximately estimated by least squares algorithm at first, and then a current statistical model and an adaptive algorithm are employed. The simulation results show that the novel least squares adaptive algorithm is of higher tracking precision than Singer algorithm in tracking the target with constant velocity or acceleration, and that it is able to estimate effectively the velocity and acceleration of the maneuvering target, in which case Singer algorithm does not work.
2005, 27(5): 797-800.
Abstract:
With differential time offset and differential frequency offset, the position of the satellite interference can be located by using two-satellite techniques. The position equations are non-linear and they are very difficult to be solved. Scholar Haworth, et al. presented an iterative algorithm. However, the position results by using their iterative algorithm were non-convergent in the experiment. The formulas given by scholar Haworth, et al. are deduced carefully in this paper and some faults of their iterative algorithm are found. Then the iterative algoritltm presented by scholar Haworth, et al. is amended in this paper and the amendment is backed up with a successful measurement in the experiment.
With differential time offset and differential frequency offset, the position of the satellite interference can be located by using two-satellite techniques. The position equations are non-linear and they are very difficult to be solved. Scholar Haworth, et al. presented an iterative algorithm. However, the position results by using their iterative algorithm were non-convergent in the experiment. The formulas given by scholar Haworth, et al. are deduced carefully in this paper and some faults of their iterative algorithm are found. Then the iterative algoritltm presented by scholar Haworth, et al. is amended in this paper and the amendment is backed up with a successful measurement in the experiment.
2005, 27(5): 801-804.
Abstract:
For the pattern synthesis of antenna arrays by using genetic algorithm, it is important to select a proper objective function, which greatly influences the result and efficiency of the algorithm. In this paper, some kinds of objective functions used in the pattern synthesis are introduced and compared. A general objective function is presented, which can be used in many kinds of pattern synthesis problems. Meanwhile, the influence of weight factor in the objective function is studied.
For the pattern synthesis of antenna arrays by using genetic algorithm, it is important to select a proper objective function, which greatly influences the result and efficiency of the algorithm. In this paper, some kinds of objective functions used in the pattern synthesis are introduced and compared. A general objective function is presented, which can be used in many kinds of pattern synthesis problems. Meanwhile, the influence of weight factor in the objective function is studied.
2005, 27(5): 805-810.
Abstract:
A Quantum probability Coding Genetic Algorithm-QCGA is proposed, which is different from classical GAs. In QCGA, single individual represents a probability distribution of solutions, which covers the whole solution space. Individuals in QCGA evolve independently and in parallel. A new crossover operator is designed to implement the information exchange among individuals. A new mutation operator is also design to prevent the algorithm from falling into local optima. To study the efficiency and advantage of QCGA, the algorithm is applied to solve function optimization problems, knapsack problems, and to discover frequent structures from time series. Experimental results show that QCGA has good ability of global optimization, and good ability of diversity reservation, which makes it efficient for complex optimization problems.
A Quantum probability Coding Genetic Algorithm-QCGA is proposed, which is different from classical GAs. In QCGA, single individual represents a probability distribution of solutions, which covers the whole solution space. Individuals in QCGA evolve independently and in parallel. A new crossover operator is designed to implement the information exchange among individuals. A new mutation operator is also design to prevent the algorithm from falling into local optima. To study the efficiency and advantage of QCGA, the algorithm is applied to solve function optimization problems, knapsack problems, and to discover frequent structures from time series. Experimental results show that QCGA has good ability of global optimization, and good ability of diversity reservation, which makes it efficient for complex optimization problems.
2005, 27(5): 811-813.
Abstract:
In this paper, an quantum signature scheme is presented which based on the entanglement swapping. In this scheme, Alice performs a local unitary operation on her two qubits according to message code, after swapping qubits with administrator and Bob, Alice gets the signature by measure her qubits, Bob can verify signature via the measurement outcomes of three sides. This scheme is secure absolutely, it can be applied in a quantum communication network, as well as quantum identification, and it is easy to realize by the present-day technologies.
In this paper, an quantum signature scheme is presented which based on the entanglement swapping. In this scheme, Alice performs a local unitary operation on her two qubits according to message code, after swapping qubits with administrator and Bob, Alice gets the signature by measure her qubits, Bob can verify signature via the measurement outcomes of three sides. This scheme is secure absolutely, it can be applied in a quantum communication network, as well as quantum identification, and it is easy to realize by the present-day technologies.
2005, 27(5): 814-818.
Abstract:
Biochemical reaction theory based DNA computation is of much better performance in solving a class of intractable computational problems such as NP-complete problems, it is important to study the DNA computation. A novel algorithm based on DNA computation is proposed, which solves the problem of a category of special integer planning problem by using the method of fluorescence labeling in the surface based approach to DNA computation. By utilizing the techniques of fluorescence distinguishing, the new algorithm can eliminate all of those false solutions through observing the fluorescence on the surface of DNA molecules. Algorithm analyses show that the new proposed algorithm based on DNA computation has such good characteristics as simple encoding and low fault rate etc.
Biochemical reaction theory based DNA computation is of much better performance in solving a class of intractable computational problems such as NP-complete problems, it is important to study the DNA computation. A novel algorithm based on DNA computation is proposed, which solves the problem of a category of special integer planning problem by using the method of fluorescence labeling in the surface based approach to DNA computation. By utilizing the techniques of fluorescence distinguishing, the new algorithm can eliminate all of those false solutions through observing the fluorescence on the surface of DNA molecules. Algorithm analyses show that the new proposed algorithm based on DNA computation has such good characteristics as simple encoding and low fault rate etc.
2005, 27(5): 819-822.
Abstract:
The conditions of the steady operation of the amplifiers are analyzed based on the characteristics of beam-wave interactions of harmonic gyroklystron amplifiers in this paper. The optimized design parameters of the circuit of the beam-wave interactions are obtained by simulation and calculation of the beam-wave interactions of a Ka-band, second harmonic, three cavities gyroklystron amplifier. The results show that this gyroklystron amplifier can produce an output peak power of over 250kW with more than 21dB gain and 23% maximum efficiency at 35GHz with a 70kV, 15A electron beam, and a 3dB bandwidth of about 120 MHz. This work is beneficial to the actual engineering design of the Ka-band second harmonic gyroklystron amplifier.
The conditions of the steady operation of the amplifiers are analyzed based on the characteristics of beam-wave interactions of harmonic gyroklystron amplifiers in this paper. The optimized design parameters of the circuit of the beam-wave interactions are obtained by simulation and calculation of the beam-wave interactions of a Ka-band, second harmonic, three cavities gyroklystron amplifier. The results show that this gyroklystron amplifier can produce an output peak power of over 250kW with more than 21dB gain and 23% maximum efficiency at 35GHz with a 70kV, 15A electron beam, and a 3dB bandwidth of about 120 MHz. This work is beneficial to the actual engineering design of the Ka-band second harmonic gyroklystron amplifier.
2005, 27(5): 823-826.
Abstract:
This paper analyzes the restrictive conditions, proposes a mapping of ternary function with mutually exclusive variables and the graphic simplification rules. It can greatly reduce the size of K-map, and has several advantages such as intuition, convenience easily operating on computers.
This paper analyzes the restrictive conditions, proposes a mapping of ternary function with mutually exclusive variables and the graphic simplification rules. It can greatly reduce the size of K-map, and has several advantages such as intuition, convenience easily operating on computers.
2005, 27(5): 835-837.
Abstract:
A new learning algorithm of fuzzy classification rules is presented based on ensemble learning algorithm. By tuning the distribution of training instances during each AdaBoost iterative training, the classification rules with fuzzy antecedent and consequent are produced with genetic algorithm. The distribution of training instances participate in computing of the fitness function and the collaboration of rules which are complementary is taken into account during rules producing, so that the classification error rate is reduced and performance of the classification based on the fuzzy rules is improved.
A new learning algorithm of fuzzy classification rules is presented based on ensemble learning algorithm. By tuning the distribution of training instances during each AdaBoost iterative training, the classification rules with fuzzy antecedent and consequent are produced with genetic algorithm. The distribution of training instances participate in computing of the fitness function and the collaboration of rules which are complementary is taken into account during rules producing, so that the classification error rate is reduced and performance of the classification based on the fuzzy rules is improved.
2005, 27(5): 838-840.
Abstract:
A novel modulation mode named Fuzzy Pulse Skip Modulation(FPSM) in power converter is proposed in this paper, which is based on Pulse Skip Modulation(PSM) mode proposed by authors recently. PSM is a novel modulation mode in power converter, which has high efficiency, quick response and strong robust qualities. This paper gives the membership function, fuzzy rule and analysis results of FPSM. It is shown that FPSM not only has high efficiency, quick response and strong robust characteristics, but also decreases the ripple of output voltage and eliminates audible noise through analysis and simulation.
A novel modulation mode named Fuzzy Pulse Skip Modulation(FPSM) in power converter is proposed in this paper, which is based on Pulse Skip Modulation(PSM) mode proposed by authors recently. PSM is a novel modulation mode in power converter, which has high efficiency, quick response and strong robust qualities. This paper gives the membership function, fuzzy rule and analysis results of FPSM. It is shown that FPSM not only has high efficiency, quick response and strong robust characteristics, but also decreases the ripple of output voltage and eliminates audible noise through analysis and simulation.
2005, 27(5): 753-756.
Abstract:
An optimal approach for enhancing a speech signal degraded by uncorrelated stationary additive noise, which exploits auditory perception properties, is proposed. The speech spectra estimate is performed in two cases: noisy speech spectra for noise masked and classical estimate for noise unmasked. Taking account into the uncertainty of the noise presence, the enhanced speech signal spectra are obtained by a weighted sum of these two estimates, where the weights are given by the noise masked probability. The performance of the proposed speech enhancement approach has been evaluated with speech distortion and informal listening tests. Comparing with Aziranis method and classical estimator, results show that a better compromise between reducing speech distortion and reinforcing noise suppression has been made, speech distortion has been decreased apparently, musical noise has been suppressed and speech articulation has been improved.
An optimal approach for enhancing a speech signal degraded by uncorrelated stationary additive noise, which exploits auditory perception properties, is proposed. The speech spectra estimate is performed in two cases: noisy speech spectra for noise masked and classical estimate for noise unmasked. Taking account into the uncertainty of the noise presence, the enhanced speech signal spectra are obtained by a weighted sum of these two estimates, where the weights are given by the noise masked probability. The performance of the proposed speech enhancement approach has been evaluated with speech distortion and informal listening tests. Comparing with Aziranis method and classical estimator, results show that a better compromise between reducing speech distortion and reinforcing noise suppression has been made, speech distortion has been decreased apparently, musical noise has been suppressed and speech articulation has been improved.
2005, 27(5): 827-834.
Abstract:
MANET is a multi-hop temporary autonomous system of mobile nodes equipped with wireless transmitters and receivers without the aid of any current network infrastructure. Batteries typically power hosts in MANET, so energy conservation strategy is a critical criterion in routing protocol. The energy saving strategy is surveyed, some strategics are described and evaluated. Finally, the new research direction of the field is pointed out.
MANET is a multi-hop temporary autonomous system of mobile nodes equipped with wireless transmitters and receivers without the aid of any current network infrastructure. Batteries typically power hosts in MANET, so energy conservation strategy is a critical criterion in routing protocol. The energy saving strategy is surveyed, some strategics are described and evaluated. Finally, the new research direction of the field is pointed out.
