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2006 Vol. 28, No. 11
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2006, 28(11): 1985-1988.
Abstract:
It is possible that the input signal-to-noise ratio of different radars may be different and their reliable estimation may be impossible in practical multiradar distributed detection scenario. So the most robust fusion rule is 1 out of N, which has severe signal-to-noise ratio loss comparable with the whole detection schemes potential. A new type of quarternary local decision based distributed detection algorithm is presented where the fusion center firstly perform three kinds of k out of N fusion and then fuses the obtained decision. Monte Carlo simulation revealed that the proposed algorithm has better detection performance than 1 out of N based scheme and can work well when the input SNRs change violently. So it is a robust distributed detection algorithm.
It is possible that the input signal-to-noise ratio of different radars may be different and their reliable estimation may be impossible in practical multiradar distributed detection scenario. So the most robust fusion rule is 1 out of N, which has severe signal-to-noise ratio loss comparable with the whole detection schemes potential. A new type of quarternary local decision based distributed detection algorithm is presented where the fusion center firstly perform three kinds of k out of N fusion and then fuses the obtained decision. Monte Carlo simulation revealed that the proposed algorithm has better detection performance than 1 out of N based scheme and can work well when the input SNRs change violently. So it is a robust distributed detection algorithm.
2006, 28(11): 1989-1993.
Abstract:
The topic of scattering matrix measurement of moving targets is very important in such fields as polarimetric radar and target recognition. In this paper, the problem of time division scattering matrix measurement of the reciprocal targets is discussed. A method of measuring and calibration based on aligning the phase of the cross-polarization of the scattering matrix is proposed. It is shown that the proposed measuring and calibration method can effectively eliminate the scattering matrix decorrelation caused by the target movement.
The topic of scattering matrix measurement of moving targets is very important in such fields as polarimetric radar and target recognition. In this paper, the problem of time division scattering matrix measurement of the reciprocal targets is discussed. A method of measuring and calibration based on aligning the phase of the cross-polarization of the scattering matrix is proposed. It is shown that the proposed measuring and calibration method can effectively eliminate the scattering matrix decorrelation caused by the target movement.
2006, 28(11): 1994-1997.
Abstract:
HF ground wave radar encounters intense interference and clutter during operation in ocean environment. This paper presents an improved adaptive beamforming algorithm introducing clutter constraints which do not destroy the temporal coherence of first-order sea clutter and broaden frequency spectrum falsely after interference suppression. Furthermore, Singular Value Decomposition (SVD) for matrix constructed by interference suppressed data is employed to track frequency evolvement of first-order sea clutter during CIT and clear procedure by eigenvalue analysis is proposed. Experimental results demonstrate the effectiveness of presented algorithm using data acquired by OSMAR2000.
HF ground wave radar encounters intense interference and clutter during operation in ocean environment. This paper presents an improved adaptive beamforming algorithm introducing clutter constraints which do not destroy the temporal coherence of first-order sea clutter and broaden frequency spectrum falsely after interference suppression. Furthermore, Singular Value Decomposition (SVD) for matrix constructed by interference suppressed data is employed to track frequency evolvement of first-order sea clutter during CIT and clear procedure by eigenvalue analysis is proposed. Experimental results demonstrate the effectiveness of presented algorithm using data acquired by OSMAR2000.
2006, 28(11): 1998-2002.
Abstract:
In this paper, a new method which is based on anisotropic diffusion equation for INSAR phase noise reduction is proposed. With the local statistics values, the new method provides anisotropic diffusion in the heterogenous area and isotropic diffusion in the homogeneous area. In the experiment, the new method is proved good performance in reducing INSAR phase noise and preserves edges and details at the same time. Furthermore, the filtered INSAR phase can be unwrapped successfully.
In this paper, a new method which is based on anisotropic diffusion equation for INSAR phase noise reduction is proposed. With the local statistics values, the new method provides anisotropic diffusion in the heterogenous area and isotropic diffusion in the homogeneous area. In the experiment, the new method is proved good performance in reducing INSAR phase noise and preserves edges and details at the same time. Furthermore, the filtered INSAR phase can be unwrapped successfully.
2006, 28(11): 2003-2006.
Abstract:
The estimation of the wave velocity underground and synthetic aperture imaging are two of the key issues in the research of ground penetrating radar (GPR). In this paper the image processing methods are introduced into the GPR velocity estimation and synthetic aperture imaging based on the characteristic of the GPR image. A new GPR velocity estimation method is proposed based on template matching and the fast synthetic aperture imaging method is proposed based on the image segmentation. The experimental result shows that the methods proposed are effective.
The estimation of the wave velocity underground and synthetic aperture imaging are two of the key issues in the research of ground penetrating radar (GPR). In this paper the image processing methods are introduced into the GPR velocity estimation and synthetic aperture imaging based on the characteristic of the GPR image. A new GPR velocity estimation method is proposed based on template matching and the fast synthetic aperture imaging method is proposed based on the image segmentation. The experimental result shows that the methods proposed are effective.
2006, 28(11): 2007-2010.
Abstract:
A concept of difference degree which is based on the coherence of the covariance matrices and the power difference is given in this paper. An iterative method of classification is proposed based on difference degree. This new method not only reduces the compute, but also needs not apriority information of the targets compared with Wishart classifier. This new classifier is applied to the polarimetric SAR image of Hong Kong from the NSAS/JPL SIR-C data and gets an excellent classification result.
A concept of difference degree which is based on the coherence of the covariance matrices and the power difference is given in this paper. An iterative method of classification is proposed based on difference degree. This new method not only reduces the compute, but also needs not apriority information of the targets compared with Wishart classifier. This new classifier is applied to the polarimetric SAR image of Hong Kong from the NSAS/JPL SIR-C data and gets an excellent classification result.
2006, 28(11): 2011-2014.
Abstract:
Distributed satellites Interferometric Synthetic Aperture Radar (InSAR) can provide large baseline, by which the sensitivity to topography measure can be improved. But large baseline arises the difficulty in phase unwrapping procedures. Combined the characteristic of multibaseline of distributed satellites InSAR system, a method that utilizes the multibaseline data fusion is proposed to solve the problem of phase unwrapping brought by large baseline in this paper. Maximum likelihood (ML) method that is an effective two-baseline data fusion algorithm is adopted to estimate interferometric phase of distributed satellites InSAR system. The simulation results show that the phase unwrapping accuracy via multibaseline data fusion is higher than that of direct phase unwrapping of large baseline interferometric phase.
Distributed satellites Interferometric Synthetic Aperture Radar (InSAR) can provide large baseline, by which the sensitivity to topography measure can be improved. But large baseline arises the difficulty in phase unwrapping procedures. Combined the characteristic of multibaseline of distributed satellites InSAR system, a method that utilizes the multibaseline data fusion is proposed to solve the problem of phase unwrapping brought by large baseline in this paper. Maximum likelihood (ML) method that is an effective two-baseline data fusion algorithm is adopted to estimate interferometric phase of distributed satellites InSAR system. The simulation results show that the phase unwrapping accuracy via multibaseline data fusion is higher than that of direct phase unwrapping of large baseline interferometric phase.
2006, 28(11): 2015-2018.
Abstract:
Because of the limitation of the PCs velocity and capability, it is difficult to simulate SAR real scenarios in time-domain. In this paper, a novel method of SAR real scenario raw data simulation, frequency-domain simulation, is introduced. This method employs space-frequency relationship, other than the traditional time-frequency relationship. After 2D FFT, the scenarios data are interpolated and shifted. Then these data are multiplied by the transfer function of frequency-domain, and followed by IFFT. The simulated raw data can be obtained. The validity of this method is fully manifested by the simulation experiments of point target and the real scenarios. The result show that the method in this paper, compared with the time-domain methods, greatly improve the simulation speed.
Because of the limitation of the PCs velocity and capability, it is difficult to simulate SAR real scenarios in time-domain. In this paper, a novel method of SAR real scenario raw data simulation, frequency-domain simulation, is introduced. This method employs space-frequency relationship, other than the traditional time-frequency relationship. After 2D FFT, the scenarios data are interpolated and shifted. Then these data are multiplied by the transfer function of frequency-domain, and followed by IFFT. The simulated raw data can be obtained. The validity of this method is fully manifested by the simulation experiments of point target and the real scenarios. The result show that the method in this paper, compared with the time-domain methods, greatly improve the simulation speed.
2006, 28(11): 2019-2021.
Abstract:
A new robust method about location on TDOA is proposed in this paper. It use the known TDOAs variance bound and the error bound of the radars position, to solve the psdolinear equations about TDOA, the algorithm is robust, and its performance is better and have a higher location precision than the others.
A new robust method about location on TDOA is proposed in this paper. It use the known TDOAs variance bound and the error bound of the radars position, to solve the psdolinear equations about TDOA, the algorithm is robust, and its performance is better and have a higher location precision than the others.
2006, 28(11): 2022-2025.
Abstract:
To absolve image blur phenomena caused by relative motion between camera and objects, a real-time blur image restoration method is put forward, which is composed of three fixed point DSP and one float point DSP. Degeneration model is researched, from the point of view of software, wiener filtering is adopted to restore image. Two-dimensional FFT principle and important questions are presented executed by fixed DSP, the respective functions of four DSP is explained during the course of image restoration. For the image of 512512，the time of two-dimensional FFT by fixed DSP is 17.7ms, the gross time of float point multiplication and division by float point DSP is 32.51ms, according to above time, the load of every DSP is calculated. From these datum, the hardware can complete real-time restoration of 512512 image.
To absolve image blur phenomena caused by relative motion between camera and objects, a real-time blur image restoration method is put forward, which is composed of three fixed point DSP and one float point DSP. Degeneration model is researched, from the point of view of software, wiener filtering is adopted to restore image. Two-dimensional FFT principle and important questions are presented executed by fixed DSP, the respective functions of four DSP is explained during the course of image restoration. For the image of 512512，the time of two-dimensional FFT by fixed DSP is 17.7ms, the gross time of float point multiplication and division by float point DSP is 32.51ms, according to above time, the load of every DSP is calculated. From these datum, the hardware can complete real-time restoration of 512512 image.
2006, 28(11): 2026-2029.
Abstract:
A new method of digital modulation identification with wavelet transform is introduced in this paper. There are two ways to get the characteristics. One is to get the local maximum with the continuous wavelet transform; the other is the multiresolution analysis. Both of them have been used. For different modulated signals, different characteristics have been used. Compared with others, the classifier is easy to realize and the decision is simple. It is not necessary to estimate the code period and the synchronization time. The percentage of correct identification is improved. The speed of modulation identification is increased as well.
A new method of digital modulation identification with wavelet transform is introduced in this paper. There are two ways to get the characteristics. One is to get the local maximum with the continuous wavelet transform; the other is the multiresolution analysis. Both of them have been used. For different modulated signals, different characteristics have been used. Compared with others, the classifier is easy to realize and the decision is simple. It is not necessary to estimate the code period and the synchronization time. The percentage of correct identification is improved. The speed of modulation identification is increased as well.
2006, 28(11): 2030-2032.
Abstract:
In order to improve the actual effect of exhaustive method, which is applied to synthesize the linear thinned arrays (whose elements are thinned from the uniform grid), a new method of exhaustive method with divisional pre-processing is proposed in this article firstly, and then the Divisional Exhaustive (DE) is compared with other methods of optimizing arrays. Finally, the simulated results showing the performance (actual effect and advantages) of this method are presented.
In order to improve the actual effect of exhaustive method, which is applied to synthesize the linear thinned arrays (whose elements are thinned from the uniform grid), a new method of exhaustive method with divisional pre-processing is proposed in this article firstly, and then the Divisional Exhaustive (DE) is compared with other methods of optimizing arrays. Finally, the simulated results showing the performance (actual effect and advantages) of this method are presented.
2006, 28(11): 2033-2036.
Abstract:
To overcome some shortcomings of existing algorithms which separate the mixture of super- and sub-gaussian sources, a parameter kurtosis-dependent flexible Blind Source Separation (BBS) algorithm is proposed. A weighed double Gaussian model is proposed to estimate super-Gaussian and sub-Gaussian probability density. In the framework of natural gradient, model parameter is calculated online by kurtosis. Applied to images mixing, experiment shows the proposed algorithm can successfully separate the mixture of super- and sub-gaussian images. Meanwhile experiment also shows that the proposed algorithm has better performance and convergence than existing algorithms.
To overcome some shortcomings of existing algorithms which separate the mixture of super- and sub-gaussian sources, a parameter kurtosis-dependent flexible Blind Source Separation (BBS) algorithm is proposed. A weighed double Gaussian model is proposed to estimate super-Gaussian and sub-Gaussian probability density. In the framework of natural gradient, model parameter is calculated online by kurtosis. Applied to images mixing, experiment shows the proposed algorithm can successfully separate the mixture of super- and sub-gaussian images. Meanwhile experiment also shows that the proposed algorithm has better performance and convergence than existing algorithms.
2006, 28(11): 2037-2040.
Abstract:
It is a difficult problem to denoise in the low SNR, recently, Emir et al present a novel ICA denoising method, this method has been successfully applied to the function optical imaging. But in the very low SNR circumstance, because of the covariance matrix of the observed signals being singularity, the ICA denoising method can not be used. In order to resolve this problem, a new SICA denoising method based on the signal subspace is presented in this paper. The simulations show that compared to the ICA denoising method and the traditional filtering denoising methods, the method can not only get rid of the noise, but can successfully separation the signals.
It is a difficult problem to denoise in the low SNR, recently, Emir et al present a novel ICA denoising method, this method has been successfully applied to the function optical imaging. But in the very low SNR circumstance, because of the covariance matrix of the observed signals being singularity, the ICA denoising method can not be used. In order to resolve this problem, a new SICA denoising method based on the signal subspace is presented in this paper. The simulations show that compared to the ICA denoising method and the traditional filtering denoising methods, the method can not only get rid of the noise, but can successfully separation the signals.
2006, 28(11): 2041-2044.
Abstract:
This paper presents a non-uniform and part-searching-area algebraic codebook based on Algebraic Code Excited Linear Preiction(ACELP) speech coding algorithm. The non-uniform algebraic codebook is determined by the non-uniform statistical properties of the algebraic codebook, and the part-searching-area is determined by the periodicity of the algebraic codebook excitation vector, which makes up the insufficient numbers of signed pulses in algebraic codebook at low bit rate. In order to preserve the continuity of pitch, different pitch detection methods are employed for speech/silence frame when these two techniques are used. Subjective and objective test results indicate that the reconstructed speech quality of 4kb/s DP-CELP speech coder is improved based on these techniques, especially for the female speakers.
This paper presents a non-uniform and part-searching-area algebraic codebook based on Algebraic Code Excited Linear Preiction(ACELP) speech coding algorithm. The non-uniform algebraic codebook is determined by the non-uniform statistical properties of the algebraic codebook, and the part-searching-area is determined by the periodicity of the algebraic codebook excitation vector, which makes up the insufficient numbers of signed pulses in algebraic codebook at low bit rate. In order to preserve the continuity of pitch, different pitch detection methods are employed for speech/silence frame when these two techniques are used. Subjective and objective test results indicate that the reconstructed speech quality of 4kb/s DP-CELP speech coder is improved based on these techniques, especially for the female speakers.
2006, 28(11): 2045-2049.
Abstract:
Combination of acoustic models trained from different unit sets is studied in this paper. For Chinese continuous speech recognition, Prevailing unit sets include context-dependent initial-final unit set and context-dependent phone unit set. Through experiments it is discovered that some Chinese syllables have higher recognition rates under initial-final model while some have higher recognition rates under phone model. In this paper, a method is proposed to combine these two acoustic models. On one hand the two acoustic models can be fully utilized during the recognition process; on the other hand, some models that lead to low recognition rate will not be used. Experiments show that in comparison with initial-final model and phone model, syllable error rate is reduced by 9.60% and 6.10% respectively after using the provided method.
Combination of acoustic models trained from different unit sets is studied in this paper. For Chinese continuous speech recognition, Prevailing unit sets include context-dependent initial-final unit set and context-dependent phone unit set. Through experiments it is discovered that some Chinese syllables have higher recognition rates under initial-final model while some have higher recognition rates under phone model. In this paper, a method is proposed to combine these two acoustic models. On one hand the two acoustic models can be fully utilized during the recognition process; on the other hand, some models that lead to low recognition rate will not be used. Experiments show that in comparison with initial-final model and phone model, syllable error rate is reduced by 9.60% and 6.10% respectively after using the provided method.
2006, 28(11): 2050-2053.
Abstract:
Usually the sensor colored noise is modeled as an AutoregRessive (AR) process. This paper proposes six multisensor measurement fusion algorithms by generalizing the single sensor filtering methods with colored noise. The performance of the algorithms, such as estimation accuracy, computation cost and flexibility is compared by covariance analysis technique and two simulation examples. Some conclusions are valuable to choose algorithm in the engineering applications.
Usually the sensor colored noise is modeled as an AutoregRessive (AR) process. This paper proposes six multisensor measurement fusion algorithms by generalizing the single sensor filtering methods with colored noise. The performance of the algorithms, such as estimation accuracy, computation cost and flexibility is compared by covariance analysis technique and two simulation examples. Some conclusions are valuable to choose algorithm in the engineering applications.
2006, 28(11): 2054-2057.
Abstract:
An adaptive genetic search algorithm is developed for fusion of two spatially registered images of the same scene. In this method, the size of block is defined as chromosome, after crossover and mutation, the global optimal image will be got. Three evaluation criteria such as root mean square error, entropy and mutual information are used on the analysis and effect evaluation of different fused images. Two cases are discussed and extensive experiments demonstrate that in one case the method achieves reconstruction or optimized fusion result to the reference image when the focus objectives are not overlapping blurred, and in another case this method performs better outperforming Laplacian and wavelet methods when the focus objectives are overlapping blurred.
An adaptive genetic search algorithm is developed for fusion of two spatially registered images of the same scene. In this method, the size of block is defined as chromosome, after crossover and mutation, the global optimal image will be got. Three evaluation criteria such as root mean square error, entropy and mutual information are used on the analysis and effect evaluation of different fused images. Two cases are discussed and extensive experiments demonstrate that in one case the method achieves reconstruction or optimized fusion result to the reference image when the focus objectives are not overlapping blurred, and in another case this method performs better outperforming Laplacian and wavelet methods when the focus objectives are overlapping blurred.
2006, 28(11): 2058-2062.
Abstract:
A fast Multi-Scan Multi-Space Data Association (MSMSDA) algorithm for multiple targets is presented based on wavelet transform in this paper. With the introduction of wavelet transform, the data association is extended to multiple scan. The MSMSDA need not any prior knowledge and plays good performance in the complex clutter environment. The performance of the MSMSDA is evaluated in the multiple passive sensor multiple target tracking system in this paper. Simulations show that the proposed new algorithm has lower computational complexity and better performance of data association than the joint probabilistic data association (JPDA), etc., under complex clutter environment.
A fast Multi-Scan Multi-Space Data Association (MSMSDA) algorithm for multiple targets is presented based on wavelet transform in this paper. With the introduction of wavelet transform, the data association is extended to multiple scan. The MSMSDA need not any prior knowledge and plays good performance in the complex clutter environment. The performance of the MSMSDA is evaluated in the multiple passive sensor multiple target tracking system in this paper. Simulations show that the proposed new algorithm has lower computational complexity and better performance of data association than the joint probabilistic data association (JPDA), etc., under complex clutter environment.
2006, 28(11): 2063-2067.
Abstract:
A novel Turbo-BLAST scheme over frequency selective fading environment is presented in this paper. At the transmitter grouped linear constellation precoded OFDM transmission is employed following the Random Layered Space Time (RLST) coding to exploit the available both multipath and spatial diversity. At the receiver the Turbo receivers with MMSE detector and Sphere Decoding (SD) based detector are compared to explore the tradeoff between performance and complexity. Simulation results demonstrate that the available transmit diversity offered by MIMO environment can be efficiently utilized in the new scheme, while the high data rate from BLAST is retained.
A novel Turbo-BLAST scheme over frequency selective fading environment is presented in this paper. At the transmitter grouped linear constellation precoded OFDM transmission is employed following the Random Layered Space Time (RLST) coding to exploit the available both multipath and spatial diversity. At the receiver the Turbo receivers with MMSE detector and Sphere Decoding (SD) based detector are compared to explore the tradeoff between performance and complexity. Simulation results demonstrate that the available transmit diversity offered by MIMO environment can be efficiently utilized in the new scheme, while the high data rate from BLAST is retained.
2006, 28(11): 2068-2072.
Abstract:
This paper proposes a receive space diversity scheme based on space-time block coding for Single-Carrier block transmission system employing Frequency Domain Equalization (SC/FDE), which can remedy the Huangs (2004) system performance degradation, and can also reduce the number of IDFT blocks. It can further increase data transmission rate through properly designing the space-time codes. A detailed procession for SC/FDE systems using space-time block coding is given, and the performances between the proposed SC/FDE-MIMO system and the MIMO-OFDM system are compared; effective benefits can be shown in the simulations.
This paper proposes a receive space diversity scheme based on space-time block coding for Single-Carrier block transmission system employing Frequency Domain Equalization (SC/FDE), which can remedy the Huangs (2004) system performance degradation, and can also reduce the number of IDFT blocks. It can further increase data transmission rate through properly designing the space-time codes. A detailed procession for SC/FDE systems using space-time block coding is given, and the performances between the proposed SC/FDE-MIMO system and the MIMO-OFDM system are compared; effective benefits can be shown in the simulations.
2006, 28(11): 2073-2076.
Abstract:
A new method based on amplitude-only perturbations for the pattern synthesis of linear antenna array with prescribed nulls is proposed. It is capable of steering narrow and broad nulls with satisfactory nulls depth in the directions of strong interference signals and acceptable sidelobe level in the beam pattern without affecting the main beam. The phase shifters are only used to steer the main beam toward the desired direction. In so doing, the responsed time can be reduced. Simulation results show that this method is easier to realize, and its capability is comparable to that of controlling complex weights (both amplitude and phase). Besides, the fact that the amplitude perturbations of the elements are symmetrical about the center of the array means that the amount of attenuators is halved.
A new method based on amplitude-only perturbations for the pattern synthesis of linear antenna array with prescribed nulls is proposed. It is capable of steering narrow and broad nulls with satisfactory nulls depth in the directions of strong interference signals and acceptable sidelobe level in the beam pattern without affecting the main beam. The phase shifters are only used to steer the main beam toward the desired direction. In so doing, the responsed time can be reduced. Simulation results show that this method is easier to realize, and its capability is comparable to that of controlling complex weights (both amplitude and phase). Besides, the fact that the amplitude perturbations of the elements are symmetrical about the center of the array means that the amount of attenuators is halved.
2006, 28(11): 2077-2080.
Abstract:
This paper proposes a robust pilot-assisted channel estimation method for Orthogonal Frequency Division Multiplexing(OFDM) signals in Rayleigh fading. The method can be used in rectangular pilot-assisted geometry, which is more efficient than the comb pilot-assisted geometry. Comparing with the Linear Minimum Mean Square Error (LMMSE) channel estimation method, the method is simple and need not know the channel correlation and signal-to-noise (SNR). The performance is presented in terms of bit-error rate(BER) for a system using QPSK and 16QAM in fading channel.
This paper proposes a robust pilot-assisted channel estimation method for Orthogonal Frequency Division Multiplexing(OFDM) signals in Rayleigh fading. The method can be used in rectangular pilot-assisted geometry, which is more efficient than the comb pilot-assisted geometry. Comparing with the Linear Minimum Mean Square Error (LMMSE) channel estimation method, the method is simple and need not know the channel correlation and signal-to-noise (SNR). The performance is presented in terms of bit-error rate(BER) for a system using QPSK and 16QAM in fading channel.
2006, 28(11): 2081-2085.
Abstract:
This article presents an Active ACK segments Forwarding Control (AAFC) scheme to make efficiency and fairness tradeoff for TCP over UMTS. One important MAC issue in UMTS is the packet scheduling and a rather detailed simulation model evaluates the performance of TCP over UMTS. It shows that efficiency requirements and fairness requirements are difficult to guarantee at the same time only by proper packet scheduling in MAC-layer. So a cross-layer scheme AAFC is presented, which communicate between MAC-layer and Transport-layer. The basic idea of AAFC is to control the transmission of ACK segments at base station in such a way that the all the users have fair TCP throughput and the maximization of resource utilization in link-layer is guaranteed. Simulation results demonstrate effectiveness of the AAFC scheme.
This article presents an Active ACK segments Forwarding Control (AAFC) scheme to make efficiency and fairness tradeoff for TCP over UMTS. One important MAC issue in UMTS is the packet scheduling and a rather detailed simulation model evaluates the performance of TCP over UMTS. It shows that efficiency requirements and fairness requirements are difficult to guarantee at the same time only by proper packet scheduling in MAC-layer. So a cross-layer scheme AAFC is presented, which communicate between MAC-layer and Transport-layer. The basic idea of AAFC is to control the transmission of ACK segments at base station in such a way that the all the users have fair TCP throughput and the maximization of resource utilization in link-layer is guaranteed. Simulation results demonstrate effectiveness of the AAFC scheme.
2006, 28(11): 2086-2089.
Abstract:
This paper presents a pre-repeat GBN ARQ scheme, which suits for slowly fading TDD system. The normalized throughputs also analysed and compared between the proposed scheme and Nakamura Osamus. It turns out that, depending on the normalized throughput, the optimum scheme is one of the two following alternatives: (1) in the higher throughput, Nakamura Osamus scheme is better; (2) in the lower cases, the proposed scheme works better and is more robust to the error prediction. Simulation results verify that the scheme improves the throughput efficiency: the gain is about 4 dB when the normalized throughput is around 0.6.
This paper presents a pre-repeat GBN ARQ scheme, which suits for slowly fading TDD system. The normalized throughputs also analysed and compared between the proposed scheme and Nakamura Osamus. It turns out that, depending on the normalized throughput, the optimum scheme is one of the two following alternatives: (1) in the higher throughput, Nakamura Osamus scheme is better; (2) in the lower cases, the proposed scheme works better and is more robust to the error prediction. Simulation results verify that the scheme improves the throughput efficiency: the gain is about 4 dB when the normalized throughput is around 0.6.
2006, 28(11): 2090-2093.
Abstract:
Distributed virtual group cell systems become a possible solution for future wireless communication systems, which has flexible structure and huge potential in terms of increasing spectrum efficiency and improving quality of communications. In this paper, a Markov model is adopted to analyze the performance of multi-antenna based virtual group cell systems. Numerical results, such as blocking probability, handoff failure probability etc., are given with interference-based admission control algorithm. The investigation shows that the uplink performance of this system can be improved greatly.
Distributed virtual group cell systems become a possible solution for future wireless communication systems, which has flexible structure and huge potential in terms of increasing spectrum efficiency and improving quality of communications. In this paper, a Markov model is adopted to analyze the performance of multi-antenna based virtual group cell systems. Numerical results, such as blocking probability, handoff failure probability etc., are given with interference-based admission control algorithm. The investigation shows that the uplink performance of this system can be improved greatly.
2006, 28(11): 2094-2098.
Abstract:
The Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) technique is widely accepted as the most prospective technique for broadband wireless communications. Previous studies have put emphasis on how to utilize space channels between receiving and emitting antennas. For the first time, a new conception of wide-sense space channels is proposed which combined antenna channels and beam channels. With no increasing the number of antennas, wide-sense space channels can increase the number of space channels. Under the condition of the multi-paths number was greater than the array elements number, the correlations among frequency responses of wide-sense space channels are very weak, hence, the diversity, coding and multiplexing gain of Space-Frequency Code (SFC) can be increased, so wide-sense space channels can improve the performance of MIMO-OFDM systems.
The Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) technique is widely accepted as the most prospective technique for broadband wireless communications. Previous studies have put emphasis on how to utilize space channels between receiving and emitting antennas. For the first time, a new conception of wide-sense space channels is proposed which combined antenna channels and beam channels. With no increasing the number of antennas, wide-sense space channels can increase the number of space channels. Under the condition of the multi-paths number was greater than the array elements number, the correlations among frequency responses of wide-sense space channels are very weak, hence, the diversity, coding and multiplexing gain of Space-Frequency Code (SFC) can be increased, so wide-sense space channels can improve the performance of MIMO-OFDM systems.
2006, 28(11): 2099-2102.
Abstract:
An algorithm of channel and carrier frequency offset joint estimation is proposed in this paper with analyzing the characteristic of carrier frequency offset and wireless channel in Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system. Frequency offset and channel parameters can be uncoupled by means of partly correlating the training sequence and calculating difference, then they are estimated accurately through iteration. Simulation results show that the proposed algorithm performs quite well in both frequency offset and channel estimation. The frequency offset estimation performance is closed to Cramr-Rao bound, and the link performance is good. The proposed method has low complexity and strong practicability. It can be used in other Time Division Duplex (TDD) CDMA systems.
An algorithm of channel and carrier frequency offset joint estimation is proposed in this paper with analyzing the characteristic of carrier frequency offset and wireless channel in Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system. Frequency offset and channel parameters can be uncoupled by means of partly correlating the training sequence and calculating difference, then they are estimated accurately through iteration. Simulation results show that the proposed algorithm performs quite well in both frequency offset and channel estimation. The frequency offset estimation performance is closed to Cramr-Rao bound, and the link performance is good. The proposed method has low complexity and strong practicability. It can be used in other Time Division Duplex (TDD) CDMA systems.
2006, 28(11): 2103-2106.
Abstract:
In this paper, a receiver is proposed for the OFDM signal with CoChannel Interference (CCI) and frequency offset. The basic idea is to perform interference suppression before frequency offset estimate. Computer simulations verify the effectiveness of the proposed receiver.
In this paper, a receiver is proposed for the OFDM signal with CoChannel Interference (CCI) and frequency offset. The basic idea is to perform interference suppression before frequency offset estimate. Computer simulations verify the effectiveness of the proposed receiver.
2006, 28(11): 2107-2110.
Abstract:
This paper investigates the Bit Error Rate (BER) of the time-frequency 2-Dimensional Spread Spectrum (2DSS) in Additive White Gaussian Noise (AWGN) channel with the presence of multi-tone jamming. Analytical results indicate that the harmful effect caused by the multi-tone jamming can be completely eliminated when the jamming signals are placed on certain sub-carriers central frequencies and if the corresponding row sums of the 2-dimensional spreading code matrix are equal to zero. The simulation results are provided, which show the agreement between theoretical analysis and simulation results.
This paper investigates the Bit Error Rate (BER) of the time-frequency 2-Dimensional Spread Spectrum (2DSS) in Additive White Gaussian Noise (AWGN) channel with the presence of multi-tone jamming. Analytical results indicate that the harmful effect caused by the multi-tone jamming can be completely eliminated when the jamming signals are placed on certain sub-carriers central frequencies and if the corresponding row sums of the 2-dimensional spreading code matrix are equal to zero. The simulation results are provided, which show the agreement between theoretical analysis and simulation results.
2006, 28(11): 2111-2115.
Abstract:
An ecologic system optimization algorithm is a type of new developed evolutionary algorithm, which is based on swarm intelligence, and has the properties of converge quickly, simple rules. This paper research the ant colony optimization algorithm and the particle swarm optimization on discrete space, and describe two algorithms for the multi-user detection problem in Code Division Multiple Access(CDMA) communication system．The approach using some new methods to improve the search quality and efficiency, analyses and simulation results show the approach has low computational complexity, and the BER property of the algorithm is better than the conventional detector, to find a new method to solve the problem of MUD in CDMA.
An ecologic system optimization algorithm is a type of new developed evolutionary algorithm, which is based on swarm intelligence, and has the properties of converge quickly, simple rules. This paper research the ant colony optimization algorithm and the particle swarm optimization on discrete space, and describe two algorithms for the multi-user detection problem in Code Division Multiple Access(CDMA) communication system．The approach using some new methods to improve the search quality and efficiency, analyses and simulation results show the approach has low computational complexity, and the BER property of the algorithm is better than the conventional detector, to find a new method to solve the problem of MUD in CDMA.
2006, 28(11): 2116-2120.
Abstract:
This paper presents a new image coding algorithm based on the Contourlet Listless Zerotree Coding (CLZC) with lower memory requirement and higher compression performance. This new algorithm adopts Zerotree structure analogical to LZC by repositioning the Contourlet coefficients. Furthermore, in order to take advantage of the good performance of Contourlet in approximation for 2D piecewise smooth functions, a reasonable scanning order and new flag maps different from LZC are designed, which reduce the complexity in the encoding and decoding procedure. The experiments demonstrate that the proposed algorithm is efficient in coding images; it outperforms the wavelet-based LZC and SPIHT algorithms both visually and in terms of PSNR under the same compression ratio, especially for the images including a large portion of texture.
This paper presents a new image coding algorithm based on the Contourlet Listless Zerotree Coding (CLZC) with lower memory requirement and higher compression performance. This new algorithm adopts Zerotree structure analogical to LZC by repositioning the Contourlet coefficients. Furthermore, in order to take advantage of the good performance of Contourlet in approximation for 2D piecewise smooth functions, a reasonable scanning order and new flag maps different from LZC are designed, which reduce the complexity in the encoding and decoding procedure. The experiments demonstrate that the proposed algorithm is efficient in coding images; it outperforms the wavelet-based LZC and SPIHT algorithms both visually and in terms of PSNR under the same compression ratio, especially for the images including a large portion of texture.
2006, 28(11): 2121-2123.
Abstract:
Based on the generator matrix of linear codes C over , F2+uF2 the generator matrixes of the dual codes C and the Gray images (C) of the linear codes C are given, and the proposition that linear codes (C) are the dual codes of (C) are showed. By using this proposition, the necessary and sufficient condition of a linear code over F2+uF2 which is self-dual is obtained.
Based on the generator matrix of linear codes C over , F2+uF2 the generator matrixes of the dual codes C and the Gray images (C) of the linear codes C are given, and the proposition that linear codes (C) are the dual codes of (C) are showed. By using this proposition, the necessary and sufficient condition of a linear code over F2+uF2 which is self-dual is obtained.
2006, 28(11): 2124-2126.
Abstract:
A new design method of period bolt interleaver based on bolt interleaver is proposed by analyzing the factors influencing the performance. This interleaver can greatly make divisible sequence be indivisible sequence and improve the weight of the output of Turbo coder. It is proved an effective method by simulation.
A new design method of period bolt interleaver based on bolt interleaver is proposed by analyzing the factors influencing the performance. This interleaver can greatly make divisible sequence be indivisible sequence and improve the weight of the output of Turbo coder. It is proved an effective method by simulation.
2006, 28(11): 2127-2129.
Abstract:
A new traitor tracing scheme is proposed , whose essential idea is the session key S is divided into a sum of S1 and S2. Based on DL(discrete logarithm)problem, S1 is decrypted by introducing a multi-channel service parameter and a special polynomial function, S2 is decrypted by Chinese Remainder Theorem. The new scheme has many advantages such as multi-service, collusion-resistance, asymmetry, long-lived subscribers key and black-box tracing. It is proved to be semantically secure under the DDH (Diffie-Hellman Problem) assumption and its whole capabilities are much better than that of the existing ones.
A new traitor tracing scheme is proposed , whose essential idea is the session key S is divided into a sum of S1 and S2. Based on DL(discrete logarithm)problem, S1 is decrypted by introducing a multi-channel service parameter and a special polynomial function, S2 is decrypted by Chinese Remainder Theorem. The new scheme has many advantages such as multi-service, collusion-resistance, asymmetry, long-lived subscribers key and black-box tracing. It is proved to be semantically secure under the DDH (Diffie-Hellman Problem) assumption and its whole capabilities are much better than that of the existing ones.
2006, 28(11): 2130-2134.
Abstract:
To improve transmission efficiency, Expectation Maximization(EM) based channel parameters estimation iteration algorithm is proposed, employed the special features of Orthogonal Frequency Division Multiplexing (OFDM) system. Channel impulse response is updated at each iteration, furthermore the noise variance is update also. To improve the algorithm convergence, EM-based joint channel parameters estimation and data detection algorithm is proposed. Simulation results demonstrate the proposed EM-based algorithm can converge to the case with known channel parameters with fewer pilots and the joint channel parameters estimation and data detection algorithm converges significantly fast.
To improve transmission efficiency, Expectation Maximization(EM) based channel parameters estimation iteration algorithm is proposed, employed the special features of Orthogonal Frequency Division Multiplexing (OFDM) system. Channel impulse response is updated at each iteration, furthermore the noise variance is update also. To improve the algorithm convergence, EM-based joint channel parameters estimation and data detection algorithm is proposed. Simulation results demonstrate the proposed EM-based algorithm can converge to the case with known channel parameters with fewer pilots and the joint channel parameters estimation and data detection algorithm converges significantly fast.
2006, 28(11): 2135-2139.
Abstract:
Parallel Packet Switch (PPS) can realize high speed switching by using low speed switches, which is a hot spot in switching area. So, this paper analyzes the current situation, and presented the PPS_RR scheduling algorithm by using the concept of flow index. The math analyzing validates that the system can guarantee packet sequence in a data flow. Finally, computer simulation shows the type of PPS has good performance on average delay.
Parallel Packet Switch (PPS) can realize high speed switching by using low speed switches, which is a hot spot in switching area. So, this paper analyzes the current situation, and presented the PPS_RR scheduling algorithm by using the concept of flow index. The math analyzing validates that the system can guarantee packet sequence in a data flow. Finally, computer simulation shows the type of PPS has good performance on average delay.
2006, 28(11): 2140-2143.
Abstract:
As the need of network user for high-availability is increased, how to evaluate the network availability just becomes an on edge problem. Then a Dynamic connections Network Availability Algorithm (DNAA) in WDM network is proposed, which considers high network performance, and the network performance is defined as that the accept rate multiplies the required availability of users. Simulation results show that DNAA is not only correct but also efficient.
As the need of network user for high-availability is increased, how to evaluate the network availability just becomes an on edge problem. Then a Dynamic connections Network Availability Algorithm (DNAA) in WDM network is proposed, which considers high network performance, and the network performance is defined as that the accept rate multiplies the required availability of users. Simulation results show that DNAA is not only correct but also efficient.
2006, 28(11): 2144-2147.
Abstract:
Optical burst switched network has been proposed as a new network scheme which can realize IP over WDM and also been regarded as the trend of the next generation network. An improved method has been proposed to solve the unfairness of burst segmentation or dropping in optical burst switched multi-hop network, this approach not only could maintain the advantage of original approach, which could make the packets loss probability coherence in multi-hop network but also could decrease the losing and increase the throughput. Finally, a simulation proves the validity of the proposed method and it has the theoretic meaning to design the real network in practice.
Optical burst switched network has been proposed as a new network scheme which can realize IP over WDM and also been regarded as the trend of the next generation network. An improved method has been proposed to solve the unfairness of burst segmentation or dropping in optical burst switched multi-hop network, this approach not only could maintain the advantage of original approach, which could make the packets loss probability coherence in multi-hop network but also could decrease the losing and increase the throughput. Finally, a simulation proves the validity of the proposed method and it has the theoretic meaning to design the real network in practice.
2006, 28(11): 2148-2151.
Abstract:
A method of Random Midpoint Displacement-Fractional Gaussian Noise (RMD-FGN) is applied to generate self-similar traffic. A link state model is presented and used to describe the wavelength usage of Wavelength Division Multiplexing (WDM) network with layered-graph model. The performance of a 55 Mesh_Torus WDM network with shared-path protection under self-similar traffic is simulated. The result shows that when the self-similar coefficient or the variance of traffic increases, that is, the burst of traffic rises, the block probability goes up and the performance of network decreases. The block probability falls as the number of wavelength per fiber grows.
A method of Random Midpoint Displacement-Fractional Gaussian Noise (RMD-FGN) is applied to generate self-similar traffic. A link state model is presented and used to describe the wavelength usage of Wavelength Division Multiplexing (WDM) network with layered-graph model. The performance of a 55 Mesh_Torus WDM network with shared-path protection under self-similar traffic is simulated. The result shows that when the self-similar coefficient or the variance of traffic increases, that is, the burst of traffic rises, the block probability goes up and the performance of network decreases. The block probability falls as the number of wavelength per fiber grows.
2006, 28(11): 2152-2156.
Abstract:
UIO(Unique Input Output) test sequences are widely used in communication protocol testing. In this paper, based on an existing fault diagnosis algorithm, an improved algorithm, which utilizes as much information of UIO test sequences as possible, is proposed. This paper full uses of verdict information given by UIO test sequences and the observed input/output immediately after the potential faulty transition to guarantee the efficient diagnosis of any single fault. Some experiments to compare the algorithm with the original one are conducted and the results show that the algorithm is more efficient.
UIO(Unique Input Output) test sequences are widely used in communication protocol testing. In this paper, based on an existing fault diagnosis algorithm, an improved algorithm, which utilizes as much information of UIO test sequences as possible, is proposed. This paper full uses of verdict information given by UIO test sequences and the observed input/output immediately after the potential faulty transition to guarantee the efficient diagnosis of any single fault. Some experiments to compare the algorithm with the original one are conducted and the results show that the algorithm is more efficient.
2006, 28(11): 2157-2161.
Abstract:
Multimedia service is the basic service in NGN. QoS multicast routing algorithms technology is one of the key technology of multimedia transfer。The network model of QoS multicast routing based on project-the key technology of the next-generation networks is presented.Some other approaches are optimized in this paper, and an approach based on genetic algorithm is proposed. The simulation results demonstrate that the proposed algorithm (NGNMR-GA) has fast convergence speed and high reliability, it can meet the requirement of the next-generation works.
Multimedia service is the basic service in NGN. QoS multicast routing algorithms technology is one of the key technology of multimedia transfer。The network model of QoS multicast routing based on project-the key technology of the next-generation networks is presented.Some other approaches are optimized in this paper, and an approach based on genetic algorithm is proposed. The simulation results demonstrate that the proposed algorithm (NGNMR-GA) has fast convergence speed and high reliability, it can meet the requirement of the next-generation works.
2006, 28(11): 2162-2166.
Abstract:
Currently, the false positive and the false negative of Intrusion Detection System are very high. It was always the main problem that bothered the user of IDS. But there are tow main technologies applied in IDS. To this problem, because both the technologies have its own advantages and they can supply for each other. So IDS combined with the tow technologies was used more and more widely. This paper presented a model of IDS based on combination of misuse detection and anomaly detection. In this model, misuse detection is based on pattern matching and Anomaly Detection is based on statistical analysis. It combined the tow technologies to reduce the false positive rate and the false negative rate in only one detection technology, and then to improve security of IDS.
Currently, the false positive and the false negative of Intrusion Detection System are very high. It was always the main problem that bothered the user of IDS. But there are tow main technologies applied in IDS. To this problem, because both the technologies have its own advantages and they can supply for each other. So IDS combined with the tow technologies was used more and more widely. This paper presented a model of IDS based on combination of misuse detection and anomaly detection. In this model, misuse detection is based on pattern matching and Anomaly Detection is based on statistical analysis. It combined the tow technologies to reduce the false positive rate and the false negative rate in only one detection technology, and then to improve security of IDS.
2006, 28(11): 2167-2170.
Abstract:
Isolation between antennas is an important index for electromagnetic compatibility (EMC) on airborne platform. Airborne platform is an electrically large object and it is difficult to analyze the isolation between antennas mounted on it only by using the Method of Moment (MoM). The Uniform geometrical Theory of Diffraction (UTD) is a kind of high frequency method and can analyze electrically large objects, however, it has poor accuracy. The hybrid MoM-UTD method is employed to analyze the isolation between antennas on airborne platform. Both accuracy and computing speed are concerned, and the numerical results agree well with the measurements.
Isolation between antennas is an important index for electromagnetic compatibility (EMC) on airborne platform. Airborne platform is an electrically large object and it is difficult to analyze the isolation between antennas mounted on it only by using the Method of Moment (MoM). The Uniform geometrical Theory of Diffraction (UTD) is a kind of high frequency method and can analyze electrically large objects, however, it has poor accuracy. The hybrid MoM-UTD method is employed to analyze the isolation between antennas on airborne platform. Both accuracy and computing speed are concerned, and the numerical results agree well with the measurements.
2006, 28(11): 2171-2174.
Abstract:
In this paper, a Method of Moments (MoM) model of packaged microstrip circuit is presented, which is described by Mixed Potential Integral-Equation (MPIE). The Greens functions of a horizontal electric dipole for the covered microstrip circuits can be expressed as the closed form by the Discrete Complex Image Method (DCIM). Then the influence of the enclosure side walls is considered by the equivalent image currents and the impendence matrix is modified further. Finally, the Eleftheriades(1996) model is extended to package model and the packaged microstrip network characteristics are extracted. The numerical results show the package effect could make an important difference on the network characteristics of the microstrip circuits.
In this paper, a Method of Moments (MoM) model of packaged microstrip circuit is presented, which is described by Mixed Potential Integral-Equation (MPIE). The Greens functions of a horizontal electric dipole for the covered microstrip circuits can be expressed as the closed form by the Discrete Complex Image Method (DCIM). Then the influence of the enclosure side walls is considered by the equivalent image currents and the impendence matrix is modified further. Finally, the Eleftheriades(1996) model is extended to package model and the packaged microstrip network characteristics are extracted. The numerical results show the package effect could make an important difference on the network characteristics of the microstrip circuits.
2006, 28(11): 2175-2178.
Abstract:
In this paper, a conical-shaped alumina ceramic pill-box windows is investigated to improve the output properties of the RF-window, such as matching characteristic, the maximum power transmission capability and heat dissipation. The basic electronical characteristic and heat dissipation have been analyzed with Ansoft HFSS software, which is helpful to the engineering design of RF-window.
In this paper, a conical-shaped alumina ceramic pill-box windows is investigated to improve the output properties of the RF-window, such as matching characteristic, the maximum power transmission capability and heat dissipation. The basic electronical characteristic and heat dissipation have been analyzed with Ansoft HFSS software, which is helpful to the engineering design of RF-window.
2006, 28(11): 2179-2181.
Abstract:
A new kind of reservoir oxide cathode is presented in this paper. The characteristics of the cathode, such as, DC and PC emission, resistance to poisoning and lifetime, are better than those of conventional oxide cathode under same conditions. The SEM of the surface emission material and the XRD of the reservoir active material of the cathode are analyzed, and the THEM (Thermionic Electronic Emission Microscopy) of the Ni-net surface of the cathode is observed, based on which the emission mechanism of the cathode is discussed.
A new kind of reservoir oxide cathode is presented in this paper. The characteristics of the cathode, such as, DC and PC emission, resistance to poisoning and lifetime, are better than those of conventional oxide cathode under same conditions. The SEM of the surface emission material and the XRD of the reservoir active material of the cathode are analyzed, and the THEM (Thermionic Electronic Emission Microscopy) of the Ni-net surface of the cathode is observed, based on which the emission mechanism of the cathode is discussed.
2006, 28(11): 2182-2185.
Abstract:
A non-uniformly sampled model to DDS is introduced, based on which an analysis of DDS phase truncation noise is deduced and some important conclusions including the explanation to this kind of spur noise are derived. Further more, a technique to restrain DDS spur noise is introduced. The Matlab simulation indicates that DDS spur noise can be effectively restrained using this technique under some restriction conditions.
A non-uniformly sampled model to DDS is introduced, based on which an analysis of DDS phase truncation noise is deduced and some important conclusions including the explanation to this kind of spur noise are derived. Further more, a technique to restrain DDS spur noise is introduced. The Matlab simulation indicates that DDS spur noise can be effectively restrained using this technique under some restriction conditions.
2006, 28(11): 2186-2190.
Abstract:
Based on analysis of traditional static and dynamic Double Edge-Triggered Flip-Flops (DETFFs), a new semi-static DETFF is proposed in this paper. PSPICE simulation shows that the proposed DETFF has correct operation. Compared with traditional static DETFFs, the proposed DETFF has significant improvement in terms of power, speed, Power-Delay-Product (PDP) and area. In addition, the performance measurement of the DETFFs is also discussed in this paper, and a new approach is proposed for testing the maximum working frequency of the DETFFs.
Based on analysis of traditional static and dynamic Double Edge-Triggered Flip-Flops (DETFFs), a new semi-static DETFF is proposed in this paper. PSPICE simulation shows that the proposed DETFF has correct operation. Compared with traditional static DETFFs, the proposed DETFF has significant improvement in terms of power, speed, Power-Delay-Product (PDP) and area. In addition, the performance measurement of the DETFFs is also discussed in this paper, and a new approach is proposed for testing the maximum working frequency of the DETFFs.
2006, 28(11): 2191-2194.
Abstract:
The conception and the structure of transition layer of 6H-SiC (0001)/ SiO2 are proposed in this paper. The hydrogenation model of SiC surface is developed by analyzing the reaction mechanism of SiC surface and HF solution. The density of surface states is lowered to unpin the Fermi level because the hydrogen passivated dangling bonds of the surface. The ideal SiC surface is formed. The model is applied to treat SiC surface of the SiC/ metal contacts, Schottky junctions with ideality factor n=1.20~1.25 and Ohmic contacts with ＝510-3 cm2~710-3 cm2 are obtained under the condition of below 100℃. Its advantages lie in not only avoiding the annealing at 800~1200℃ for Ohmic contacts, but also improving the electrical performances of the Schottky barrier contacts. The hydrogenation model of SiC surface is good agreement with experiments.
The conception and the structure of transition layer of 6H-SiC (0001)/ SiO2 are proposed in this paper. The hydrogenation model of SiC surface is developed by analyzing the reaction mechanism of SiC surface and HF solution. The density of surface states is lowered to unpin the Fermi level because the hydrogen passivated dangling bonds of the surface. The ideal SiC surface is formed. The model is applied to treat SiC surface of the SiC/ metal contacts, Schottky junctions with ideality factor n=1.20~1.25 and Ohmic contacts with ＝510-3 cm2~710-3 cm2 are obtained under the condition of below 100℃. Its advantages lie in not only avoiding the annealing at 800~1200℃ for Ohmic contacts, but also improving the electrical performances of the Schottky barrier contacts. The hydrogenation model of SiC surface is good agreement with experiments.
2006, 28(11): 2195-2198.
Abstract:
A micro amperometric immunosensor is fabricated to detect human IgG based on MEMS. The Pt electrode is deposited on silicon wafer with the sensitive area of 1 mm2. A micro reacting pool is made of SU-8 polymer and several microlitre reagent was needed. Polypyrrole is electropolymerized on the electrode to transfer the electron between the electrode and the enzyme. Glutaraldehyde is used to bind the antibody on polypyrrole. Human IgG is specifically recognized by goat anti-human IgG and horseradish peroxidase (HRP) conjugated goat anti-human IgG in sandwich way. Human IgG is scaled by detecting the current from the catalyzed reaction between HRP and H2O2. With the working potential of #61485;-0.3V, the immunosensor displayed a good linear doseresponse behavior for human IgG concentrations between 5 and 255ng/ml.A low detection limit of 5ng/ml and 3-minute response time are achieved. This micro amperometric immunosensor has many advantages such as fast response time, low detection limit, little reagent, micro bulk and easy integration with IC.
A micro amperometric immunosensor is fabricated to detect human IgG based on MEMS. The Pt electrode is deposited on silicon wafer with the sensitive area of 1 mm2. A micro reacting pool is made of SU-8 polymer and several microlitre reagent was needed. Polypyrrole is electropolymerized on the electrode to transfer the electron between the electrode and the enzyme. Glutaraldehyde is used to bind the antibody on polypyrrole. Human IgG is specifically recognized by goat anti-human IgG and horseradish peroxidase (HRP) conjugated goat anti-human IgG in sandwich way. Human IgG is scaled by detecting the current from the catalyzed reaction between HRP and H2O2. With the working potential of #61485;-0.3V, the immunosensor displayed a good linear doseresponse behavior for human IgG concentrations between 5 and 255ng/ml.A low detection limit of 5ng/ml and 3-minute response time are achieved. This micro amperometric immunosensor has many advantages such as fast response time, low detection limit, little reagent, micro bulk and easy integration with IC.
2006, 28(11): 2199-2204.
Abstract:
The theory and method of multi-source information fusion have acquired plenty of the outcomes in the past 20 years. However the theoretical framework of information fusion is not established up to the present. Recently the finite set statistics (FISST) approach, a special random set method, has been proposed by Mahler. FISST provides a fully unified probabilistic foundation for the major aspects of multi-source information fusion. This paper reviews several main aspects of the random set information fusion research that include the background, the key ideas, the theoretical framework and the applications of FISST. Finally several possible future directions of FISST are discussed.
The theory and method of multi-source information fusion have acquired plenty of the outcomes in the past 20 years. However the theoretical framework of information fusion is not established up to the present. Recently the finite set statistics (FISST) approach, a special random set method, has been proposed by Mahler. FISST provides a fully unified probabilistic foundation for the major aspects of multi-source information fusion. This paper reviews several main aspects of the random set information fusion research that include the background, the key ideas, the theoretical framework and the applications of FISST. Finally several possible future directions of FISST are discussed.
2006, 28(11): 2205-2208.
Abstract:
Data origin authentication is an important part in the multicast security architecture. Data origin authentication can be classified as repudiation and non-repudiation. In this paper, several typical data origin authentication protocols with non-repudiation are summarized according to the taxonomy of data origin authentication with non-repudiation. The advantages and shortcomings of these protocols are discussed respectively, also the problems existed are anatomized in depth. This paper is a sum-up of the protocols of data origin authentication protocols with non-repudiation at the present time. The future trend and the remaining problems of data origin authentication with non-repudiation are also discussed.
Data origin authentication is an important part in the multicast security architecture. Data origin authentication can be classified as repudiation and non-repudiation. In this paper, several typical data origin authentication protocols with non-repudiation are summarized according to the taxonomy of data origin authentication with non-repudiation. The advantages and shortcomings of these protocols are discussed respectively, also the problems existed are anatomized in depth. This paper is a sum-up of the protocols of data origin authentication protocols with non-repudiation at the present time. The future trend and the remaining problems of data origin authentication with non-repudiation are also discussed.
