Email alert
2006 Vol. 28, No. 1
Display Method:
2006, 28(1): 1-6.
Abstract:
Driven by ocean wave, the swing of a ship possesses characters of multi-cycle and randomness. In this paper, imaging method based on pendulum module is proposed for dealing with these problems. This approach develops images from linear frequency modulation components that are included in the phase history in every range bin. To compensate the three and higher order phase errors, rank two phase estimator is presented based on the available theory of rank one phase estimator. A robust auto-focus algorithm is also presented based on the Randon-Wigner algorithm and the idea of CLEAN. The effectiveness of the algorithm is verified by processing of real data.
Driven by ocean wave, the swing of a ship possesses characters of multi-cycle and randomness. In this paper, imaging method based on pendulum module is proposed for dealing with these problems. This approach develops images from linear frequency modulation components that are included in the phase history in every range bin. To compensate the three and higher order phase errors, rank two phase estimator is presented based on the available theory of rank one phase estimator. A robust auto-focus algorithm is also presented based on the Randon-Wigner algorithm and the idea of CLEAN. The effectiveness of the algorithm is verified by processing of real data.
2006, 28(1): 7-11.
Abstract:
In this paper, a new method named DSADE Despeckle with Anisotrpic Diffusion Equation which is based on anisotropic diffusion equation for SAR speckle reduction is proposed. With the local statistics values, DSADE provides anisotropic diffusion in the heterogenous area and isotropic diffusion in the homogeneous area. Thus, DSADE can not only preserve the edges and details, but also enhance them. In our experiment, DSADE is proved good performance in reducing speckle noise in SAR images and enhancing edges and details at the same time. Moreover, the filtered SAR images look good.
In this paper, a new method named DSADE Despeckle with Anisotrpic Diffusion Equation which is based on anisotropic diffusion equation for SAR speckle reduction is proposed. With the local statistics values, DSADE provides anisotropic diffusion in the heterogenous area and isotropic diffusion in the homogeneous area. Thus, DSADE can not only preserve the edges and details, but also enhance them. In our experiment, DSADE is proved good performance in reducing speckle noise in SAR images and enhancing edges and details at the same time. Moreover, the filtered SAR images look good.
2006, 28(1): 12-15.
Abstract:
In this paper, an adaptively weighed method based approach is proposed for data compression of complex-valued SAR images in frequency domain. Based on the conventional compression algorithm in frequency domain, the improved approach adopts an adaptively weighed method and preserves the characteristic of the raw SAR images well at low compression ratio (20:1). It proves the efficiency of the improved approach for data compression of complex-valued SAR images through evaluating complex spatial correlation coefficient, comparing the amplitude images of raw data and decompressed data, and displaying the correlation map visually.
In this paper, an adaptively weighed method based approach is proposed for data compression of complex-valued SAR images in frequency domain. Based on the conventional compression algorithm in frequency domain, the improved approach adopts an adaptively weighed method and preserves the characteristic of the raw SAR images well at low compression ratio (20:1). It proves the efficiency of the improved approach for data compression of complex-valued SAR images through evaluating complex spatial correlation coefficient, comparing the amplitude images of raw data and decompressed data, and displaying the correlation map visually.
2006, 28(1): 16-20.
Abstract:
In this paper, a method that is used to simulate distributed targets raw data of spaceborne polarization SAR is given. Based on the backscattering polarization matrix, the algorithm of computing distributed target backscattering coefficients is discussed. Then the process of obtaining the raw data is particularly introduced. Through analyzing the image that come from the simulated data, the conclusion can be reached that the method of simulating the polarization raw data of Spaceborne SAR is right.
In this paper, a method that is used to simulate distributed targets raw data of spaceborne polarization SAR is given. Based on the backscattering polarization matrix, the algorithm of computing distributed target backscattering coefficients is discussed. Then the process of obtaining the raw data is particularly introduced. Through analyzing the image that come from the simulated data, the conclusion can be reached that the method of simulating the polarization raw data of Spaceborne SAR is right.
2006, 28(1): 21-25.
Abstract:
A novel method is proposed for estimating the noise subspace in the case where the signals are coherent. The characters of MultiStage Wiener Filter (MSWF) show that the pre-filters of redundant stages of the MSWF can create an orthonormal basis for the noise subspace, then with the classical spatial smoothing technique and the Lanczos algorithm, the noise subspace can be quickly obtained even under the condition that coherent signals exist. The new method outperforms the eigendecomposition based method in terms of computational complexity. Finally, simulation results are presented to illustrate the performance of the proposed method for the noise subspace via the classical MUSIC estimator.
A novel method is proposed for estimating the noise subspace in the case where the signals are coherent. The characters of MultiStage Wiener Filter (MSWF) show that the pre-filters of redundant stages of the MSWF can create an orthonormal basis for the noise subspace, then with the classical spatial smoothing technique and the Lanczos algorithm, the noise subspace can be quickly obtained even under the condition that coherent signals exist. The new method outperforms the eigendecomposition based method in terms of computational complexity. Finally, simulation results are presented to illustrate the performance of the proposed method for the noise subspace via the classical MUSIC estimator.
2006, 28(1): 26-30.
Abstract:
With limited samples, SVM has stronger ability of generalization in comparison with machine learning algorithm. In this paper, the SVM is combined with the Ground Penetrating Radar(GPR) multi-object recognition, and a GPR multi-object recognition method is proposed based on the one against one SVM. The proposed method includes the GPR multi-object recognition method based on one against one SVM, the parameter selection method based on the cross-validation and the multichannel recognition method. The contrast analysis between the proposed method and the conventional neural network method is given. The proposed method can be combined with object-feature extraction methods. It is shown that the method is effective in the experimental analysis. The conclusion can direct the research on GPR object recognition.
With limited samples, SVM has stronger ability of generalization in comparison with machine learning algorithm. In this paper, the SVM is combined with the Ground Penetrating Radar(GPR) multi-object recognition, and a GPR multi-object recognition method is proposed based on the one against one SVM. The proposed method includes the GPR multi-object recognition method based on one against one SVM, the parameter selection method based on the cross-validation and the multichannel recognition method. The contrast analysis between the proposed method and the conventional neural network method is given. The proposed method can be combined with object-feature extraction methods. It is shown that the method is effective in the experimental analysis. The conclusion can direct the research on GPR object recognition.
2006, 28(1): 31-35.
Abstract:
In the system of Displaced Phase Centre Multiple Azimuth Beams (DPCMAB) of spaceborne SAR，the transmitter blinding and nadir echo eclipsing events can lead to nonuniform azimuth sampling that results in the appearance of unexpected peaks on the both sides of mainlobe of azimuth impulse response. In this paper，the Spectral-Fit method and the reconstruction in time domain method are adopted to eliminate the effect due to azimuth nonuniform sampling with the quality of image being unaffected. Contrasting the number of arithmetic operations of the above two methods, it is shown that the reconstruction in time domain method is superior to the Spectral-Fit method.
In the system of Displaced Phase Centre Multiple Azimuth Beams (DPCMAB) of spaceborne SAR，the transmitter blinding and nadir echo eclipsing events can lead to nonuniform azimuth sampling that results in the appearance of unexpected peaks on the both sides of mainlobe of azimuth impulse response. In this paper，the Spectral-Fit method and the reconstruction in time domain method are adopted to eliminate the effect due to azimuth nonuniform sampling with the quality of image being unaffected. Contrasting the number of arithmetic operations of the above two methods, it is shown that the reconstruction in time domain method is superior to the Spectral-Fit method.
2006, 28(1): 36-40.
Abstract:
A novel 1-D scattering center extraction method based on genetic algorithm and its applicable conditions are provided in this paper. The undamped exponential model and CLEAN method are used in the extraction algorithm to transform 1-D scattering center extraction into non-linear optimization problem with genetic algorithm. Experimental results show that the proposed extraction method has advantages in accuracy, robustness and range resolution, comparing with the FFT and Prony methods.
A novel 1-D scattering center extraction method based on genetic algorithm and its applicable conditions are provided in this paper. The undamped exponential model and CLEAN method are used in the extraction algorithm to transform 1-D scattering center extraction into non-linear optimization problem with genetic algorithm. Experimental results show that the proposed extraction method has advantages in accuracy, robustness and range resolution, comparing with the FFT and Prony methods.
2006, 28(1): 41-44.
Abstract:
Under certain conditions, combining the polyphase filtering structure of decimation filter, put forward an optimum design method of quadrature demodulation receiver, which owns decimation structure. With the same number of multipliers in FPGA, the order of FIR filter in receiver with above optimum structure is nearly 4 times than it implemented in direct way. Finally the design instance is given.
Under certain conditions, combining the polyphase filtering structure of decimation filter, put forward an optimum design method of quadrature demodulation receiver, which owns decimation structure. With the same number of multipliers in FPGA, the order of FIR filter in receiver with above optimum structure is nearly 4 times than it implemented in direct way. Finally the design instance is given.
2006, 28(1): 45-49.
Abstract:
In this paper, the problem of the frequency, bearing and range estimate in near field is considered. Only using second statistics and corresponding pairing program, the proposed algorithm can estimate parameters. The method does not need spectral peak searching, and can avoid using fourth-order cumulant, reduce calculating burden. The effectiveness of the method is demonstrated through some simulation examples.
In this paper, the problem of the frequency, bearing and range estimate in near field is considered. Only using second statistics and corresponding pairing program, the proposed algorithm can estimate parameters. The method does not need spectral peak searching, and can avoid using fourth-order cumulant, reduce calculating burden. The effectiveness of the method is demonstrated through some simulation examples.
2006, 28(1): 50-54.
Abstract:
In this paper, a post nonlinear blind sources separation method is proposed. The demixing system of the post nonlinear mixtures is modeled using a functional link artificial neural network whose weights can be determined under the criterion of independence of its outputs. A criterion of independence based on higher order statistics is used to measure the statistical dependence of the outputs of the demixing system, and the differential evolution algorithm is utilized to minimize the criterion. The proposed method takes advantage of less learning parameters, high learning convergence rate of parameters, nonlinear approximation capability of the functional link artificial neural network, and few easily chosen control parameters, global optimization capability of the differential evolution algorithm. Compared to conventional post nonlinear blind sources separation approaches, the proposed approach for post-nonlinear blind source separation is characterized by less computational load, high convergence rate, high accuracy and robustness. Simulation results show that the proposed approach is capable of separating independent sources from their post-nonlinear mixtures.
In this paper, a post nonlinear blind sources separation method is proposed. The demixing system of the post nonlinear mixtures is modeled using a functional link artificial neural network whose weights can be determined under the criterion of independence of its outputs. A criterion of independence based on higher order statistics is used to measure the statistical dependence of the outputs of the demixing system, and the differential evolution algorithm is utilized to minimize the criterion. The proposed method takes advantage of less learning parameters, high learning convergence rate of parameters, nonlinear approximation capability of the functional link artificial neural network, and few easily chosen control parameters, global optimization capability of the differential evolution algorithm. Compared to conventional post nonlinear blind sources separation approaches, the proposed approach for post-nonlinear blind source separation is characterized by less computational load, high convergence rate, high accuracy and robustness. Simulation results show that the proposed approach is capable of separating independent sources from their post-nonlinear mixtures.
2006, 28(1): 55-59.
Abstract:
In the background of phase ambiguity in using phase interferometer to estimate the direction of arrival, a new method is proposed for estimation direction of arrival by using interferometer array with the algorithm named as multi-pare unwrap ambiguity. The possibility of correction is analyzed. The conclusion is verified by simulation result.
In the background of phase ambiguity in using phase interferometer to estimate the direction of arrival, a new method is proposed for estimation direction of arrival by using interferometer array with the algorithm named as multi-pare unwrap ambiguity. The possibility of correction is analyzed. The conclusion is verified by simulation result.
2006, 28(1): 60-65.
Abstract:
Traditional FFT can effectively analyze the sinusoidal signal, but the very big error exists for analyzing the similar frequency sinusoidal signal. In this article, adopting Least Square (LS) method which can separate similar frequency sinusoidal signal is put forward. Characteristic parameters of separating similar frequency sinusoidal signal can be identified by satisfying termination criterion of 2-norm minimum and solving overdetermined equations on observation matrix. The simulation result shows that each component of similar frequency signal such as amplitude, phase angle can be separated from original signal, the interference of noise can effectively be restrained, noise stability and the frequency domain analysis ability become better, so the efficiency and precision of signal processing can be raised.
Traditional FFT can effectively analyze the sinusoidal signal, but the very big error exists for analyzing the similar frequency sinusoidal signal. In this article, adopting Least Square (LS) method which can separate similar frequency sinusoidal signal is put forward. Characteristic parameters of separating similar frequency sinusoidal signal can be identified by satisfying termination criterion of 2-norm minimum and solving overdetermined equations on observation matrix. The simulation result shows that each component of similar frequency signal such as amplitude, phase angle can be separated from original signal, the interference of noise can effectively be restrained, noise stability and the frequency domain analysis ability become better, so the efficiency and precision of signal processing can be raised.
2006, 28(1): 66-71.
Abstract:
In this paper, a multiscale distributed hierarchical algorithm is developed to solve the computational complexity in inverse problem with multiple observation sources.Firstly, algorithm implements wavelet transform respeetively on the object signal data obtained from multiple observation processes. Secondty, the wavelet transform coefficients are estimated about object signal using the data from each sensor. Thirdty，all local estimates are efficiently fused based on the information provided by relative error covariance matrix，in order to get a global-information-based estimate of the wavelet transform coefficients with the object signal. Fourthty，the inverse wavelet transform is performed on the scaling coefficients at the coarsest scale and the wavelet coefficients at all scales to obtain the global-information-based estimator. Finally, the performance of the algorithm is evaluated with respect to the RECM-based criterion. It is comcluded that the distributed hierarchical fusion algorithm can not only result in an estimator comparable to that of the method of using central fusion algorithm with relatively light computational load, but also enhance the practicability of new algorithm.
In this paper, a multiscale distributed hierarchical algorithm is developed to solve the computational complexity in inverse problem with multiple observation sources.Firstly, algorithm implements wavelet transform respeetively on the object signal data obtained from multiple observation processes. Secondty, the wavelet transform coefficients are estimated about object signal using the data from each sensor. Thirdty，all local estimates are efficiently fused based on the information provided by relative error covariance matrix，in order to get a global-information-based estimate of the wavelet transform coefficients with the object signal. Fourthty，the inverse wavelet transform is performed on the scaling coefficients at the coarsest scale and the wavelet coefficients at all scales to obtain the global-information-based estimator. Finally, the performance of the algorithm is evaluated with respect to the RECM-based criterion. It is comcluded that the distributed hierarchical fusion algorithm can not only result in an estimator comparable to that of the method of using central fusion algorithm with relatively light computational load, but also enhance the practicability of new algorithm.
2006, 28(1): 72-75.
Abstract:
Current GISs lack efficient management and analysis functions for coastline dynamic changes for coastline is a special line object. In order to resolve this problem, the concept of stationary points is introduced, and a coastline analysis method is put forward based on current GISs. Through analyzing stationary points, the dynamic changes of coastal siltation or erosion can be obtained. Thus, the analysis of coastline changes can be accomplished automatically. In this paper, experimental analysis is performed on the real coastline data of Yellow River Mouth, which turns out that this dynamic analysis method is valid.
Current GISs lack efficient management and analysis functions for coastline dynamic changes for coastline is a special line object. In order to resolve this problem, the concept of stationary points is introduced, and a coastline analysis method is put forward based on current GISs. Through analyzing stationary points, the dynamic changes of coastal siltation or erosion can be obtained. Thus, the analysis of coastline changes can be accomplished automatically. In this paper, experimental analysis is performed on the real coastline data of Yellow River Mouth, which turns out that this dynamic analysis method is valid.
2006, 28(1): 76-79.
Abstract:
A novel method for redshift determination and spectral line identification of celestial spectra is presented, which is based on the knowledge of feature spectral lines. Firstly, definition of redshift candidate and feature spectral line candidate is given, and the candidates are cross-validated according to the definition; Secondly, the density is estimated at every redshift candidate by using the Parzen window technique; Finally, the average of redshift candidates in Parzen window of the redshift candidate with maximum density is the redshift, and the feature spectral line candidates corresponding to those redshift candidates are feature spectral lines. Compared with other methods of the same kind, this method has a lower dependence on the quality of spectral line extraction. Experiments show that this method is robust and the correct rate is encouraging.
A novel method for redshift determination and spectral line identification of celestial spectra is presented, which is based on the knowledge of feature spectral lines. Firstly, definition of redshift candidate and feature spectral line candidate is given, and the candidates are cross-validated according to the definition; Secondly, the density is estimated at every redshift candidate by using the Parzen window technique; Finally, the average of redshift candidates in Parzen window of the redshift candidate with maximum density is the redshift, and the feature spectral line candidates corresponding to those redshift candidates are feature spectral lines. Compared with other methods of the same kind, this method has a lower dependence on the quality of spectral line extraction. Experiments show that this method is robust and the correct rate is encouraging.
2006, 28(1): 80-85.
Abstract:
In this paper, three families of Bent sequences that can be quickly generated are presented. Then based on the analysis of correlation of geometric sequences by Klapper in 1993, a family of Gold-like sequences is recursively constructed, which contains the Gold-like sequences constructed in 2002 by Khoo, Gong and Stinson. On account of the theory of Olsen, Scholtz and Welch, three Bent sequence families used in a DS CDMA system can be quickly obtained by the Bent sequences here. And sequence families with large periods can be obtained by Gold-like sequences recursively constructed.
In this paper, three families of Bent sequences that can be quickly generated are presented. Then based on the analysis of correlation of geometric sequences by Klapper in 1993, a family of Gold-like sequences is recursively constructed, which contains the Gold-like sequences constructed in 2002 by Khoo, Gong and Stinson. On account of the theory of Olsen, Scholtz and Welch, three Bent sequence families used in a DS CDMA system can be quickly obtained by the Bent sequences here. And sequence families with large periods can be obtained by Gold-like sequences recursively constructed.
2006, 28(1): 86-91.
Abstract:
This paper shows how to construct generalized low-density (GLD) codes from Hamming-component product codes. Combining the decoding algorithms for linear block and LDPC codes，a novel Chase-MP algorithm for decoding of product codes is proposed by using the bipartite graph of the constructed sparse matrix. Since there are no cycles of length 4 or 6 in the graph, dependence among extrinsic information is greatly reduced during iterations and decoding performance is also improved. Experimental simulations for the (63,57,3)2 product code based on Hamming-component codes in terms of Bit Error Rate (BER) on the Additive White Gaussian Noise (AWGN) and Rayleigh fading channels show that our algorithm has remarkable coding gains. In comparison with the serially iterative Chase-2 algorithm, the Chase-MP algorithm is more convenient for fully parallelizable decoding and can achieve better performance.
This paper shows how to construct generalized low-density (GLD) codes from Hamming-component product codes. Combining the decoding algorithms for linear block and LDPC codes，a novel Chase-MP algorithm for decoding of product codes is proposed by using the bipartite graph of the constructed sparse matrix. Since there are no cycles of length 4 or 6 in the graph, dependence among extrinsic information is greatly reduced during iterations and decoding performance is also improved. Experimental simulations for the (63,57,3)2 product code based on Hamming-component codes in terms of Bit Error Rate (BER) on the Additive White Gaussian Noise (AWGN) and Rayleigh fading channels show that our algorithm has remarkable coding gains. In comparison with the serially iterative Chase-2 algorithm, the Chase-MP algorithm is more convenient for fully parallelizable decoding and can achieve better performance.
2006, 28(1): 92-95.
Abstract:
A novel vector sensors array calibration method based on subspace approaches in the presence of phase errors on high-resolution estimation methods is presented in this paper. Because of the complexity of vector sensors, the available methods for estimating the channel phase errors of the scalar sensors are not suitable for vector sensors. The computational formulas of the channel phase errors are derived in this paper. Finally, simulation results verify the effectiveness of the new algorithm.
A novel vector sensors array calibration method based on subspace approaches in the presence of phase errors on high-resolution estimation methods is presented in this paper. Because of the complexity of vector sensors, the available methods for estimating the channel phase errors of the scalar sensors are not suitable for vector sensors. The computational formulas of the channel phase errors are derived in this paper. Finally, simulation results verify the effectiveness of the new algorithm.
2006, 28(1): 96-99.
Abstract:
This paper presented a nulling algorithm for array antenna based on Immune genetic algorithm, which can suppress jamming with DOA different from signals effectively. The algorithm combines the evolution function of traditional genetic with vaccine injecting and density mechanism in creatures immune procedure. The adjustment of antibodies is realized by the expected breed rate, also the convergence rate is improved by the injected vaccine. Simulation results show that the algorithm is efficient and robust.
This paper presented a nulling algorithm for array antenna based on Immune genetic algorithm, which can suppress jamming with DOA different from signals effectively. The algorithm combines the evolution function of traditional genetic with vaccine injecting and density mechanism in creatures immune procedure. The adjustment of antibodies is realized by the expected breed rate, also the convergence rate is improved by the injected vaccine. Simulation results show that the algorithm is efficient and robust.
2006, 28(1): 100-102.
Abstract:
In this paper , a method of the Aperture-Integration, Surface-Integration and Adaptive Grid (AI-SI-AG)for ultra-wideband airborne radome analysis is presented. The theoretical results byAI-SI-AG and measured data are given. It is found that by this method the pattern of omni-directional-antenna and directional-antenna enclosed in radome can be computed efficiciently and the theoretical results agree with measurement quite well. It has shown significant practical value in engineering applications.
In this paper , a method of the Aperture-Integration, Surface-Integration and Adaptive Grid (AI-SI-AG)for ultra-wideband airborne radome analysis is presented. The theoretical results byAI-SI-AG and measured data are given. It is found that by this method the pattern of omni-directional-antenna and directional-antenna enclosed in radome can be computed efficiciently and the theoretical results agree with measurement quite well. It has shown significant practical value in engineering applications.
2006, 28(1): 103-107.
Abstract:
The Luneburg lens antenna is composed of a series of concentric shells of constant permittivity. Considering the complexity of numerical calculation, this paper presents a closed-form approach, which combines the spherical vector wave method and the reciprocity theorem. The hybrid method first calculates the scattered fields of the Luneburg lens using the spherical vector wave method. Then it transforms the calculated results into the radiation fields in the far region using the reciprocity theorem. This paper applies the approach to investigate the characteristics of the Luneburg lens in the focal region as well as in the far region. The effects of the shell number and the air gaps between the layers on the antenna performance have been also investigated. In the end, the paper presents the analysis result on the feasibility of the multiple-beam Luneburg lens antenna for satellite communication.
The Luneburg lens antenna is composed of a series of concentric shells of constant permittivity. Considering the complexity of numerical calculation, this paper presents a closed-form approach, which combines the spherical vector wave method and the reciprocity theorem. The hybrid method first calculates the scattered fields of the Luneburg lens using the spherical vector wave method. Then it transforms the calculated results into the radiation fields in the far region using the reciprocity theorem. This paper applies the approach to investigate the characteristics of the Luneburg lens in the focal region as well as in the far region. The effects of the shell number and the air gaps between the layers on the antenna performance have been also investigated. In the end, the paper presents the analysis result on the feasibility of the multiple-beam Luneburg lens antenna for satellite communication.
2006, 28(1): 112-115.
Abstract:
Based on the given channel error model and Reed-Soloman Erasure (RSE) coding scheme, the relation between file successful distribution probability as well as throughput efficiency versus length of file, length of packet, number of receiving stations and the error correcting capacity of RSE is studied in the paper. The results are valuable for the parameter selection and performance optimization in satellite data distribution systems.
Based on the given channel error model and Reed-Soloman Erasure (RSE) coding scheme, the relation between file successful distribution probability as well as throughput efficiency versus length of file, length of packet, number of receiving stations and the error correcting capacity of RSE is studied in the paper. The results are valuable for the parameter selection and performance optimization in satellite data distribution systems.
2006, 28(1): 116-121.
Abstract:
This paper proposed two new decoders for space-time block coded multiuser system over time-selective fading channels. For space-time block coded multiuser system, the design of conventional Zero Forcing (ZF) and Minimum Mean Squared Error (MMSE) decoder is based on the assuming that channels are quasi-static. When the channels are time-selective fading, these conventional decoders induce the Inter-Symbol Interference (ISI), in order to obtain one users signals, furthermore, the ISI becomes larger resulted from the increase of the channels time variations. So, this paper designed two new decoders and these decoders reduced greatly the influence of the channels time variations. Simulation results show that the both conventional decoders exhibit error floors, whereas the new decoders obtain more notable performance gains as the increase of Signal-to-Noise Ratio (SNR) values.
This paper proposed two new decoders for space-time block coded multiuser system over time-selective fading channels. For space-time block coded multiuser system, the design of conventional Zero Forcing (ZF) and Minimum Mean Squared Error (MMSE) decoder is based on the assuming that channels are quasi-static. When the channels are time-selective fading, these conventional decoders induce the Inter-Symbol Interference (ISI), in order to obtain one users signals, furthermore, the ISI becomes larger resulted from the increase of the channels time variations. So, this paper designed two new decoders and these decoders reduced greatly the influence of the channels time variations. Simulation results show that the both conventional decoders exhibit error floors, whereas the new decoders obtain more notable performance gains as the increase of Signal-to-Noise Ratio (SNR) values.
2006, 28(1): 122-125.
Abstract:
In MIMO DS/CDMA systems, the different transmit/receive antenna pairs have different frequency offset, which increases the complexity of the frequency offset estimating. Based on the cyclostationarity of the signal, a blind frequency offset estimating is proposed in this paper. The advantages of the estimating are: (1) It can separately estimate the frequency offset of the different antenna pair; (2) It is a blind estimator and does not need training sequence which lower the efficiency of the wireless bandwidth; (3) It can fully utilize the cyclic correlation of the received signal at all nonzero cyclic frequency. The simulation results provided in this paper show that the estimating has good performance in the FIR channel environment.
In MIMO DS/CDMA systems, the different transmit/receive antenna pairs have different frequency offset, which increases the complexity of the frequency offset estimating. Based on the cyclostationarity of the signal, a blind frequency offset estimating is proposed in this paper. The advantages of the estimating are: (1) It can separately estimate the frequency offset of the different antenna pair; (2) It is a blind estimator and does not need training sequence which lower the efficiency of the wireless bandwidth; (3) It can fully utilize the cyclic correlation of the received signal at all nonzero cyclic frequency. The simulation results provided in this paper show that the estimating has good performance in the FIR channel environment.
2006, 28(1): 126-129.
Abstract:
The performance of Maximum Likelihood Detector (MLD), decorrelating detector which based on multi-code detections and MMSE Multi-User Detector(MUD) of MIMO CDMA system under Rayleigh fading channels were analyzed in the paper. The relation between the number of antennas and system capacity at a given SNR was also analyzed. The numerical results present that the capacity is degressive for MMSE MUD, MLD with interference covariance known, MLD with interference covariance unknown, and decorrelating detector, furthermore the three latter detectors all have platform as SNR is large; at a given SNR, the relation of system capacity and the number of antenna is linear for a NN system.
The performance of Maximum Likelihood Detector (MLD), decorrelating detector which based on multi-code detections and MMSE Multi-User Detector(MUD) of MIMO CDMA system under Rayleigh fading channels were analyzed in the paper. The relation between the number of antennas and system capacity at a given SNR was also analyzed. The numerical results present that the capacity is degressive for MMSE MUD, MLD with interference covariance known, MLD with interference covariance unknown, and decorrelating detector, furthermore the three latter detectors all have platform as SNR is large; at a given SNR, the relation of system capacity and the number of antenna is linear for a NN system.
2006, 28(1): 130-134.
Abstract:
In this paper, the impact of spatial fading correlation on Multiple-Input Multiple-Output Spatial Multiplexing (MIMO-SM) systems is investigated, where antenna selection and soft canceller with iterative decoding is considered. It turns out that the number of receive antennas to be selected at the receiver plays an important part when dealing with high antennas correlation in flat fading channel. To mitigate the effects of highly spatial correlation at the transmitter while hardware costs and computational burden are tolerable, the variable receive antennas is selected to obtain different receiver diversity. It will be shown via simulation that in some cases this adaptive antenna selection scheme with two transmit antennas and four receive antennas offers better frame error rate performance than the simple row Correlation-Based Method (CBM).
In this paper, the impact of spatial fading correlation on Multiple-Input Multiple-Output Spatial Multiplexing (MIMO-SM) systems is investigated, where antenna selection and soft canceller with iterative decoding is considered. It turns out that the number of receive antennas to be selected at the receiver plays an important part when dealing with high antennas correlation in flat fading channel. To mitigate the effects of highly spatial correlation at the transmitter while hardware costs and computational burden are tolerable, the variable receive antennas is selected to obtain different receiver diversity. It will be shown via simulation that in some cases this adaptive antenna selection scheme with two transmit antennas and four receive antennas offers better frame error rate performance than the simple row Correlation-Based Method (CBM).
2006, 28(1): 135-138.
Abstract:
An Order-Interference-Cancellation (OIC) detection scheme is presented for Distributed Transmit Antennas Vertical Bell Labs Layered Space-Time (DTA-V-BLAST) systems. Some preliminary simulation results in single-path Rayleigh fading channel show that this algorithm can be used in the system with arbitrary receive antennas, the average bit error rate (BER) performance of this OIC approach is more 3dB better than using direct Zero-Frocing(ZF) scheme on the higher SNR (above 20dB). The capability of DTA-V-BLAST-OIC is better than the Golden scheme used in the V-BLAST signals with co-location transmit antennas with the same SNR.
An Order-Interference-Cancellation (OIC) detection scheme is presented for Distributed Transmit Antennas Vertical Bell Labs Layered Space-Time (DTA-V-BLAST) systems. Some preliminary simulation results in single-path Rayleigh fading channel show that this algorithm can be used in the system with arbitrary receive antennas, the average bit error rate (BER) performance of this OIC approach is more 3dB better than using direct Zero-Frocing(ZF) scheme on the higher SNR (above 20dB). The capability of DTA-V-BLAST-OIC is better than the Golden scheme used in the V-BLAST signals with co-location transmit antennas with the same SNR.
2006, 28(1): 139-142.
Abstract:
In this paper a new method for frequency offset estimation is proposed where the training sequence is composed of two Constant Amplitude Zero Auto Correlation (CAZAC) sequences in one OFDM symbol and the frequency offset up to OFDM bandwidth can be detected. The training sequence also can be used for channel estimation and equalization. This will enhance the efficiency of data transmission. Cramer-Rao bound can be reached in the estimation. The valid of the algorithm is verified in AWGN channel and Rayleigh channel.
In this paper a new method for frequency offset estimation is proposed where the training sequence is composed of two Constant Amplitude Zero Auto Correlation (CAZAC) sequences in one OFDM symbol and the frequency offset up to OFDM bandwidth can be detected. The training sequence also can be used for channel estimation and equalization. This will enhance the efficiency of data transmission. Cramer-Rao bound can be reached in the estimation. The valid of the algorithm is verified in AWGN channel and Rayleigh channel.
2006, 28(1): 143-146.
Abstract:
The channel estimation for Turbo coded Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems in frequency selective fading channels is studied. A method combining Turbo codes and iterative decoding with Expectation-Maximization (EM)-type iterative channel estimation algorithms is presented, which can improve the system performance greatly. The algorithms can also be applied to the very bad channel environments. Furthermore, from the simulation, the system performance with EM-type iterative channel estimation algorithms outperforms that with simplified LS channel estimation algorithms.
The channel estimation for Turbo coded Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems in frequency selective fading channels is studied. A method combining Turbo codes and iterative decoding with Expectation-Maximization (EM)-type iterative channel estimation algorithms is presented, which can improve the system performance greatly. The algorithms can also be applied to the very bad channel environments. Furthermore, from the simulation, the system performance with EM-type iterative channel estimation algorithms outperforms that with simplified LS channel estimation algorithms.
2006, 28(1): 147-150.
Abstract:
The mutual authentication between the Mobile Station(MS) and Switching and Management Infrastructure(SwMI) for TETRA is analyzed in this paper and theoretical analysis shows that some drawbacks exist when using the shared secrets in the challenge-response protocol: (1) Open attack for known text might occur once the communication security between visiting location register and home location register can not be guaranteed; (2) It is difficult to store and maintain large amount of authentication keys when the network is large. An authentication protocol for TETRA using identity-based public keys for the SwMI authenticate the MSs and an authentication protocol based on hash chain for the MSs authenticate the SwMI are presented based on the theoretical analysis, which can effectively compensate the above-mentioned drawbacks.
The mutual authentication between the Mobile Station(MS) and Switching and Management Infrastructure(SwMI) for TETRA is analyzed in this paper and theoretical analysis shows that some drawbacks exist when using the shared secrets in the challenge-response protocol: (1) Open attack for known text might occur once the communication security between visiting location register and home location register can not be guaranteed; (2) It is difficult to store and maintain large amount of authentication keys when the network is large. An authentication protocol for TETRA using identity-based public keys for the SwMI authenticate the MSs and an authentication protocol based on hash chain for the MSs authenticate the SwMI are presented based on the theoretical analysis, which can effectively compensate the above-mentioned drawbacks.
2006, 28(1): 151-153.
Abstract:
Convertible authenticated encryption schemes are studied in this paper. The problems in Wu-Hsus scheme (2002) and Huang-Changs scheme (2003) are pointed out. Furthermore the improvements of the two schemes are given; for that, the public verification of authenticated encryption schemes is solved as well.
Convertible authenticated encryption schemes are studied in this paper. The problems in Wu-Hsus scheme (2002) and Huang-Changs scheme (2003) are pointed out. Furthermore the improvements of the two schemes are given; for that, the public verification of authenticated encryption schemes is solved as well.
2006, 28(1): 154-157.
Abstract:
Steganalysis has become a hot topic recently in academia with steganograph widely used in Internet. Based on research results of Least Significant Bit (LSB) steganography in BMP images,this paper describes a run length detecting algorithm and gives the principle and realization of algorithm.The algorithm based blind detection is practical, effective, easily achieved and need not training image database when certain hypothsis conditions are met.
Steganalysis has become a hot topic recently in academia with steganograph widely used in Internet. Based on research results of Least Significant Bit (LSB) steganography in BMP images,this paper describes a run length detecting algorithm and gives the principle and realization of algorithm.The algorithm based blind detection is practical, effective, easily achieved and need not training image database when certain hypothsis conditions are met.
2006, 28(1): 158-162.
Abstract:
A new scheduler algorithm CSMA-DAMA based on the Media Access Control (MAC) sublayer is proposed, which could provide a better service for the multimedia real-time transmission. Theoretical and simulation analyses of the performance are given in which the self-similar model are used to characterize the multimedia traffic better and make the evaluation more precisel. This algorithm obtains a great improvement in the performance of the real-time data transmission and satisfies the real-time requirement of the multi-media traffic better by introducing the assignment on demand and leaky bucket algorithm.
A new scheduler algorithm CSMA-DAMA based on the Media Access Control (MAC) sublayer is proposed, which could provide a better service for the multimedia real-time transmission. Theoretical and simulation analyses of the performance are given in which the self-similar model are used to characterize the multimedia traffic better and make the evaluation more precisel. This algorithm obtains a great improvement in the performance of the real-time data transmission and satisfies the real-time requirement of the multi-media traffic better by introducing the assignment on demand and leaky bucket algorithm.
2006, 28(1): 163-167.
Abstract:
Optical Burst Switching (OBS) is considered as one of core technologies for next generation optical switching networks. In OBS network, the scheduling algorithm for core router is important for the performance of switching network. And how to schedule bursts efficientlly and reduce the lost probability of bursts are the key issue. This paper proposes a new multiple BHPs (Burst Header Packets) delayed scheduling algorithm. With this algorithm, data bursts of all BHPs collected in one collection period are schedued collectively to a policy. And resources has been arranged before for the former BHP can be altered and rearranged by the latter one, and the scheduling result is optimized. In the light of different network application, this algorithm is divided into four realities. Through simulation and comparing the results with now existing algorithms, it is showed that the algorithm can optimize the scheduling of bursts, improve the channel utilization and decrease the loss possibility of bursts.
Optical Burst Switching (OBS) is considered as one of core technologies for next generation optical switching networks. In OBS network, the scheduling algorithm for core router is important for the performance of switching network. And how to schedule bursts efficientlly and reduce the lost probability of bursts are the key issue. This paper proposes a new multiple BHPs (Burst Header Packets) delayed scheduling algorithm. With this algorithm, data bursts of all BHPs collected in one collection period are schedued collectively to a policy. And resources has been arranged before for the former BHP can be altered and rearranged by the latter one, and the scheduling result is optimized. In the light of different network application, this algorithm is divided into four realities. Through simulation and comparing the results with now existing algorithms, it is showed that the algorithm can optimize the scheduling of bursts, improve the channel utilization and decrease the loss possibility of bursts.
2006, 28(1): 168-171.
Abstract:
The concept and characters of Wireless Sensor Network (WSN) is introduced. A novel routing algorithm is created for WSN, in which minimal energy-consuming routing and maximal node-energy routing are adopted periodically, so that energy efficiency is highly improved and energy consuming is balanced over the net. A matrix algorithm of minimal energy-consuming path and a matrix algorithm of maximal node-energy path for multiple points to one point communication in WSN are given.
The concept and characters of Wireless Sensor Network (WSN) is introduced. A novel routing algorithm is created for WSN, in which minimal energy-consuming routing and maximal node-energy routing are adopted periodically, so that energy efficiency is highly improved and energy consuming is balanced over the net. A matrix algorithm of minimal energy-consuming path and a matrix algorithm of maximal node-energy path for multiple points to one point communication in WSN are given.
2006, 28(1): 172-176.
Abstract:
In this paper the complex scattering amplitude functions of a small metamaterial spheroid particle is derived. The Mueller matrix for polarimetric bistatic scattering from a layer of random metamaterial small spheroids, such as dishes or needles, is constructed. Bistatic scattering of metamaterial and dielectric spheroids are numerically calculated. Linearly co-polarized backscattering coefficients hh, vv , and hh－vv are presented to show the dependence upon frequency. The co-polarized and cross-polarized backscattering coefficients and polarizability of a layer of non-uniformly oriented metamaterial spheroids under illumination of an elliptic polarized plane wave are numerically simulated. Effects of metamaterial parameters on scattering pattern and scattering mechanism are interpreted. Numerical results indicate that scattering of metamaterial particles is enhanced largely and appears apparent directivity. Meanwhile, polarized difference of hh－vv strongly varies with frequency due to constitutive dispersion of () and ().
In this paper the complex scattering amplitude functions of a small metamaterial spheroid particle is derived. The Mueller matrix for polarimetric bistatic scattering from a layer of random metamaterial small spheroids, such as dishes or needles, is constructed. Bistatic scattering of metamaterial and dielectric spheroids are numerically calculated. Linearly co-polarized backscattering coefficients hh, vv , and hh－vv are presented to show the dependence upon frequency. The co-polarized and cross-polarized backscattering coefficients and polarizability of a layer of non-uniformly oriented metamaterial spheroids under illumination of an elliptic polarized plane wave are numerically simulated. Effects of metamaterial parameters on scattering pattern and scattering mechanism are interpreted. Numerical results indicate that scattering of metamaterial particles is enhanced largely and appears apparent directivity. Meanwhile, polarized difference of hh－vv strongly varies with frequency due to constitutive dispersion of () and ().
2006, 28(1): 177-179.
Abstract:
A new onedimensional periodic defected ground unit structure is proposed in order to improve the effective inductance. Increasing the effective inductance makes it easy to control the cutoff frequency characteristics of the DGS planar circuits. The proposed period Defected Ground Structure (DGS) provides the excellent cutoff and stopband characteristics. In order to show the improved effective inductance, three DGS circuits are fabricated with identical period and different dimensions. Measurements on the fabricated DGS circuits show that the cutoff and stopband center frequency characteristics depend on the physical dimension of the proposed unit lattice.
A new onedimensional periodic defected ground unit structure is proposed in order to improve the effective inductance. Increasing the effective inductance makes it easy to control the cutoff frequency characteristics of the DGS planar circuits. The proposed period Defected Ground Structure (DGS) provides the excellent cutoff and stopband characteristics. In order to show the improved effective inductance, three DGS circuits are fabricated with identical period and different dimensions. Measurements on the fabricated DGS circuits show that the cutoff and stopband center frequency characteristics depend on the physical dimension of the proposed unit lattice.
2006, 28(1): 180-184.
Abstract:
The development, the computer simulations of klystron and design of super broadband multiple beam klystron are introduced in this paper. It shows some results of simulation of super broadband MBK by 1.5D code Klystron-MSU and 2.5D code Arsenal-MSU. Theoretical investigations of simulation results are described in details. The results show an opportunity of realization the multiple beam klystron with bandwidth about 10～14 %, gain 40～50 dB at electronic efficiency about 40~50 %.
The development, the computer simulations of klystron and design of super broadband multiple beam klystron are introduced in this paper. It shows some results of simulation of super broadband MBK by 1.5D code Klystron-MSU and 2.5D code Arsenal-MSU. Theoretical investigations of simulation results are described in details. The results show an opportunity of realization the multiple beam klystron with bandwidth about 10～14 %, gain 40～50 dB at electronic efficiency about 40~50 %.
