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2006 Vol. 28, No. 3
Display Method:
2006, 28(3): 385-389.
Abstract:
It will create the problem of great degradation in video quality, when the digital video is compressed by using lossy video compression algorithm more than once. That will reduce the rate of reusing the digital video. Thus a new lossless video compression algorithm has been proposed. This algorithm features in: (1) an improved context-tree based arithmetic coding is proposed to compress the residual frame after motion compensation, and(2) macro-block based motion estimation and compensation method is optimized to improve the compression ratio of lossless video compression algorithm, with consideration to the improved arithmetic coding. When using JPEG-LS and CALIC, the existing state-of-the-art in lossless compression of still images, to encode those motion-compensated error-frames or residue frames to formulate benchmarks, the experiments illustrate that the proposed algorithm outperforms JPEG-LS by up to 23.3%, and CALIC by up to 19.3%.
It will create the problem of great degradation in video quality, when the digital video is compressed by using lossy video compression algorithm more than once. That will reduce the rate of reusing the digital video. Thus a new lossless video compression algorithm has been proposed. This algorithm features in: (1) an improved context-tree based arithmetic coding is proposed to compress the residual frame after motion compensation, and(2) macro-block based motion estimation and compensation method is optimized to improve the compression ratio of lossless video compression algorithm, with consideration to the improved arithmetic coding. When using JPEG-LS and CALIC, the existing state-of-the-art in lossless compression of still images, to encode those motion-compensated error-frames or residue frames to formulate benchmarks, the experiments illustrate that the proposed algorithm outperforms JPEG-LS by up to 23.3%, and CALIC by up to 19.3%.
2006, 28(3): 390-395.
Abstract:
In the traditional CBR rate control algorithm, the skipping method is adopted to combat the overflow of video buffer , in which the motion compensation error and picture distortion are increased with the number of skipping frame. To deal with the disadvantage of traditional skipping method, a new adaptive rate control algorithm with spatial scalability for video coding is presented in this paper. In the method, the original skipped frame is adaptively sub-sampled at encoder and is up-sampled in decoder. Simulation results show that this scheme can highly improve the quality of reconstructed video and obtain a gain of about0.3~0.8dB and 0.1~0.4dB in PSNR respectively compared with the traditional skipping method and the method of increasing quantization step.
In the traditional CBR rate control algorithm, the skipping method is adopted to combat the overflow of video buffer , in which the motion compensation error and picture distortion are increased with the number of skipping frame. To deal with the disadvantage of traditional skipping method, a new adaptive rate control algorithm with spatial scalability for video coding is presented in this paper. In the method, the original skipped frame is adaptively sub-sampled at encoder and is up-sampled in decoder. Simulation results show that this scheme can highly improve the quality of reconstructed video and obtain a gain of about0.3~0.8dB and 0.1~0.4dB in PSNR respectively compared with the traditional skipping method and the method of increasing quantization step.
2006, 28(3): 396-399.
Abstract:
This paper presents a blind detection method for the IPR-OFDM (Interleaving and Phase Rotation- Orthogonal Frequency Division Multiplexing) system. The proposed method is used to recover the interleaving order and detect the received data in the receiver. How to recover the original information in the receiver is the main motivation in this paper. In the IPR-OFDM system, it uses interleavers to produce permutations of the input data frame. To recovery the data, the receiver must know the interleaving order in the transmitter. In IPR-OFDM system, the Side Information(SI) is used to get it. But in this letter, a blind rate detection approach for CDMA systems can be modified and applied to the receiver structure. The interleaving order is obtained by the CRC (Cyclic Redundancy Check) and reverse SER information mainly. The blind detection can increase the channel capacity compared to that of SI method.
This paper presents a blind detection method for the IPR-OFDM (Interleaving and Phase Rotation- Orthogonal Frequency Division Multiplexing) system. The proposed method is used to recover the interleaving order and detect the received data in the receiver. How to recover the original information in the receiver is the main motivation in this paper. In the IPR-OFDM system, it uses interleavers to produce permutations of the input data frame. To recovery the data, the receiver must know the interleaving order in the transmitter. In IPR-OFDM system, the Side Information(SI) is used to get it. But in this letter, a blind rate detection approach for CDMA systems can be modified and applied to the receiver structure. The interleaving order is obtained by the CRC (Cyclic Redundancy Check) and reverse SER information mainly. The blind detection can increase the channel capacity compared to that of SI method.
2006, 28(3): 400-403.
Abstract:
A combined time and frequency acquisition algorithm for OFDM systems is derived in this paper. The proposed technique estimates the symbol beginning and the fractional frequency offset with the periodicity of Cyclic Prefix (CP), and simultaneously achieves the frame synchronization and the integral frequency offset correction based on differential pilot subcarriers in the first symbol of a transmission frame. Simulation results in MW/SW channels indicate the accuracy and practicability of this approach.
A combined time and frequency acquisition algorithm for OFDM systems is derived in this paper. The proposed technique estimates the symbol beginning and the fractional frequency offset with the periodicity of Cyclic Prefix (CP), and simultaneously achieves the frame synchronization and the integral frequency offset correction based on differential pilot subcarriers in the first symbol of a transmission frame. Simulation results in MW/SW channels indicate the accuracy and practicability of this approach.
2006, 28(3): 404-406.
Abstract:
In Elliptic Curves Cryptosystems (ECC), the optimal extension fields is preferable to others method, whether concerns performance or memory request. But, it is very difficult to choose pseudo-Mersenne prime numbers, and satisfy the condition that p just is presented by a register of processor. This paper replaces pseudo-Mersenne numbers by generalized Mersenne numbers, provides a new notation-Generalized Optimal Extension Fields(GOEFs), and studies the fast arithmetic about multiplication and modular reduction in GOEFs, finally, deduces common formulas for multiplication and some more general formulas for modular reduction in GOEFs. The results in this paper extend the corresponding work on arithmetic of Bailey, Mihǎilescu, and Woodbury in OEFs.
In Elliptic Curves Cryptosystems (ECC), the optimal extension fields is preferable to others method, whether concerns performance or memory request. But, it is very difficult to choose pseudo-Mersenne prime numbers, and satisfy the condition that p just is presented by a register of processor. This paper replaces pseudo-Mersenne numbers by generalized Mersenne numbers, provides a new notation-Generalized Optimal Extension Fields(GOEFs), and studies the fast arithmetic about multiplication and modular reduction in GOEFs, finally, deduces common formulas for multiplication and some more general formulas for modular reduction in GOEFs. The results in this paper extend the corresponding work on arithmetic of Bailey, Mihǎilescu, and Woodbury in OEFs.
2006, 28(3): 407-409.
Abstract:
Based on oblivious polynomial evaluation, this paper presents a new asymmetric public-key traitor tracing scheme. Compared with the previous schemes, this proposed scheme can accurately determine a or all traitor(s) from an illegal decoder by full black-box tracing when the number of traitors participating conspiracy is not larger than the defined number; and revoke unlimited traitors by means of the way of updating secret key. Moreover, this proposed scheme greatly decreases the computational cost of tracing a traitor and has a higher transmission efficiency compared with those of available.
Based on oblivious polynomial evaluation, this paper presents a new asymmetric public-key traitor tracing scheme. Compared with the previous schemes, this proposed scheme can accurately determine a or all traitor(s) from an illegal decoder by full black-box tracing when the number of traitors participating conspiracy is not larger than the defined number; and revoke unlimited traitors by means of the way of updating secret key. Moreover, this proposed scheme greatly decreases the computational cost of tracing a traitor and has a higher transmission efficiency compared with those of available.
2006, 28(3): 410-414.
Abstract:
In this paper the authors first present a related-key attack on chaotic stream ciphers. Combining the idea of linear cryptanalysis and divide-and-conquer attack on chaotic ciphers, the attack uses the output sequences created by multiple related keys, hence enhances the efficiency of divide-and-conquer attacks. The related-key attack breaks the confinements that it is difficult to reduce the computing complexity of divide-and-conquer attacks to a realizable range when the information amount leaked by the distribution of coincidence degree of a chaotic cipher is small or the size of key is large. As an example, the related-key attack on the ZLL chaotic cipher with 64 bits key on a Pentium 4/2.5GHz personal computer was realized and it took about 154s to recover key at a success rate 0.96.
In this paper the authors first present a related-key attack on chaotic stream ciphers. Combining the idea of linear cryptanalysis and divide-and-conquer attack on chaotic ciphers, the attack uses the output sequences created by multiple related keys, hence enhances the efficiency of divide-and-conquer attacks. The related-key attack breaks the confinements that it is difficult to reduce the computing complexity of divide-and-conquer attacks to a realizable range when the information amount leaked by the distribution of coincidence degree of a chaotic cipher is small or the size of key is large. As an example, the related-key attack on the ZLL chaotic cipher with 64 bits key on a Pentium 4/2.5GHz personal computer was realized and it took about 154s to recover key at a success rate 0.96.
2006, 28(3): 415-418.
Abstract:
In this paper a new method of OFDM channel estimation with noise reduction, based on wavelet transform, is given. The channel estimation algorithm is divided into least-squares estimation and noise reduction. The method does not need any statistical characteristic of channel and has good performance, compared with least-squares estimation. The conclusion is proved by computer simulation .
In this paper a new method of OFDM channel estimation with noise reduction, based on wavelet transform, is given. The channel estimation algorithm is divided into least-squares estimation and noise reduction. The method does not need any statistical characteristic of channel and has good performance, compared with least-squares estimation. The conclusion is proved by computer simulation .
2006, 28(3): 419-423.
Abstract:
Cooperative relaying can combat multi-path fading and shadowing effect in wireless networks to enhance communication quality and bandwidth efficiency. A two-hop relaying system model is provided in this paper, and the analytical evaluations of non-regenerative and regenerative relaying system with non-diversity or maximal ratio combining are introduced. Considering the complexity and cost-effectiveness of the receiver, this paper investigates the performance of the selection diversity in terms of probability of outage and error with different positions of relays. The numerical results show that non-regenerative relaying system outperforms the others, and selection diversity is a cost-effective method to improve system performance.
Cooperative relaying can combat multi-path fading and shadowing effect in wireless networks to enhance communication quality and bandwidth efficiency. A two-hop relaying system model is provided in this paper, and the analytical evaluations of non-regenerative and regenerative relaying system with non-diversity or maximal ratio combining are introduced. Considering the complexity and cost-effectiveness of the receiver, this paper investigates the performance of the selection diversity in terms of probability of outage and error with different positions of relays. The numerical results show that non-regenerative relaying system outperforms the others, and selection diversity is a cost-effective method to improve system performance.
2006, 28(3): 424-428.
Abstract:
An adaptive receiver scheme employing the training sequences of flexible length is proposed for DS-UWB systems. By fully exploiting the NLMS algorithms robust behavior on convergence rate, complexity and stability, the proposed scheme is capable of performing an adaptive receiver with its low cost in terms of training bits. Theoretical analysis and simulation results show that, without loss of the BER performance, the proposed scheme can achieve a simpler structure compared with the traditional coherent Rake receiver and a higher throughput compared with the conventional adaptive receiver scheme, and therefore can be considered as a promising candidate for low cost, low power consumption and low complexity indoor UWB application scenarios.
An adaptive receiver scheme employing the training sequences of flexible length is proposed for DS-UWB systems. By fully exploiting the NLMS algorithms robust behavior on convergence rate, complexity and stability, the proposed scheme is capable of performing an adaptive receiver with its low cost in terms of training bits. Theoretical analysis and simulation results show that, without loss of the BER performance, the proposed scheme can achieve a simpler structure compared with the traditional coherent Rake receiver and a higher throughput compared with the conventional adaptive receiver scheme, and therefore can be considered as a promising candidate for low cost, low power consumption and low complexity indoor UWB application scenarios.
2006, 28(3): 429-432.
Abstract:
In this paper, a method of time synchronization of 2D Spread Spectrum (2DSS) system in multipath fading channels is proposed. The detection probability and false-alarm probability are analyzed and also the numerical results on condition of different normalized thresholds are presented. The theoretical results show that the mapped 2DSS system is equal to the 1D Spread Spectrum (1DSS) system. So the synchronization algorithm in the 1DSS system can be used in 2DSS system, and good synchronization performance can be obtained and its algorithm can be simplified.
In this paper, a method of time synchronization of 2D Spread Spectrum (2DSS) system in multipath fading channels is proposed. The detection probability and false-alarm probability are analyzed and also the numerical results on condition of different normalized thresholds are presented. The theoretical results show that the mapped 2DSS system is equal to the 1D Spread Spectrum (1DSS) system. So the synchronization algorithm in the 1DSS system can be used in 2DSS system, and good synchronization performance can be obtained and its algorithm can be simplified.
2006, 28(3): 433-436.
Abstract:
As adaptive MIMO-OFDM system can greatly improve the spectral efficiency, many people are studying it. The imperfect Channel State Information (CSI), which is caused by two major factorschannel estimation error and CSI delay, and their impacts on the system frequency efficiency are studied. Simulation results show that the spectral efficiency loss due to channel estimation error is relatively small when the channel estimation error is less than-12dB and the system will be less sensitive to CSI delay when channel prediction is used.
As adaptive MIMO-OFDM system can greatly improve the spectral efficiency, many people are studying it. The imperfect Channel State Information (CSI), which is caused by two major factorschannel estimation error and CSI delay, and their impacts on the system frequency efficiency are studied. Simulation results show that the spectral efficiency loss due to channel estimation error is relatively small when the channel estimation error is less than-12dB and the system will be less sensitive to CSI delay when channel prediction is used.
2006, 28(3): 437-439.
Abstract:
This paper presents a NON-coherent Antenna Selection (NON-AS) algorithm for multi-antenna transmission system. The combination of Generalized Likelihood Ratio Test (GLRT) and Antenna Selection (AS) is applied to Unitary (U)signal transmission system, and antenna selection and signal detection do not require Channel State Information (CSI). Therefore, the NON-AS algorithm, compared with coherent antenna selection, can greatly reduce system complexity. This paper only discusses the selection of receiving antenna. Selection criterion is based on the Frobenius-2 norm of received signal vector at each receiving antenna. Simulation results indicate that under the condition of high Signal to Noise Ratio (SNR), by selecting a set of receiving antennas which observe the largest Frobenius-2 norm of received signal vector, the same diversity gain as the one obtained by using all the receiving antennas can be achieved.
This paper presents a NON-coherent Antenna Selection (NON-AS) algorithm for multi-antenna transmission system. The combination of Generalized Likelihood Ratio Test (GLRT) and Antenna Selection (AS) is applied to Unitary (U)signal transmission system, and antenna selection and signal detection do not require Channel State Information (CSI). Therefore, the NON-AS algorithm, compared with coherent antenna selection, can greatly reduce system complexity. This paper only discusses the selection of receiving antenna. Selection criterion is based on the Frobenius-2 norm of received signal vector at each receiving antenna. Simulation results indicate that under the condition of high Signal to Noise Ratio (SNR), by selecting a set of receiving antennas which observe the largest Frobenius-2 norm of received signal vector, the same diversity gain as the one obtained by using all the receiving antennas can be achieved.
2006, 28(3): 440-445.
Abstract:
The impact of Doppler on the receivers BER performance of TDD pre-equalized OFDM systems is investigated. The analytic BPSK BER expressions of amplitude and phase pre-equalized OFDM systems in multi-path Rayleigh fading environment are given, which undergoes Doppler frequency shift. The computer simulations verify theoretical results. In TDD pre-equalization OFDM systems, the Doppler frequency shift would make channel time-variant, degrade system performance. A new structure adopting Wiener predictor filter is proposed in such systems to improve system performance greatly.
The impact of Doppler on the receivers BER performance of TDD pre-equalized OFDM systems is investigated. The analytic BPSK BER expressions of amplitude and phase pre-equalized OFDM systems in multi-path Rayleigh fading environment are given, which undergoes Doppler frequency shift. The computer simulations verify theoretical results. In TDD pre-equalization OFDM systems, the Doppler frequency shift would make channel time-variant, degrade system performance. A new structure adopting Wiener predictor filter is proposed in such systems to improve system performance greatly.
2006, 28(3): 446-450.
Abstract:
There is problem of channel congestion caused by the increased channel contention in satellite communication system with Packet Reservation Multiple Access (PRMA) protocol when the payload (amount of user terminals) goes up, and the long propagation delay worsens the situation with the result of increased packet drop rate. Considering that the requirement of the voice terminal for channel resource in different phase of communication progress is different, a new scheme of PRMA named PRMA-AC is proposed, which aims to decrease the channel contention and improve the quality of service by adopting an access control mechanism. Through theoretic analysis, the system model of the new scheme is given and performance parameters such as the access block probability and the packet drop probability are obtained. Finally, the scheme is compared with several other satellite PRMA protocols by simulation, and the result validates that the scheme is effective.
There is problem of channel congestion caused by the increased channel contention in satellite communication system with Packet Reservation Multiple Access (PRMA) protocol when the payload (amount of user terminals) goes up, and the long propagation delay worsens the situation with the result of increased packet drop rate. Considering that the requirement of the voice terminal for channel resource in different phase of communication progress is different, a new scheme of PRMA named PRMA-AC is proposed, which aims to decrease the channel contention and improve the quality of service by adopting an access control mechanism. Through theoretic analysis, the system model of the new scheme is given and performance parameters such as the access block probability and the packet drop probability are obtained. Finally, the scheme is compared with several other satellite PRMA protocols by simulation, and the result validates that the scheme is effective.
2006, 28(3): 451-454.
Abstract:
Under the construction of optical networks, in order to reduce construction cost, several links may pass through a duct. In many cases, fibers fail due to duct failures. It is required to provide protection against duct failures. The paper investigates protection for dynamic multicast traffic against single duct failures. The paper explores two dedicated protection algorithms (SDP-DP, SDS-DP) and a shared protection algorithm(SDS-SDP). Block probabilities of the algorithms are assessed through simulation. Simulation results show that, in most cases, block probability of SDS-SDP is lowest since SDS-SDP shares protecting wavelengths among connection requests. When the network load is light, SDP-DP has lowest block probability.
Under the construction of optical networks, in order to reduce construction cost, several links may pass through a duct. In many cases, fibers fail due to duct failures. It is required to provide protection against duct failures. The paper investigates protection for dynamic multicast traffic against single duct failures. The paper explores two dedicated protection algorithms (SDP-DP, SDS-DP) and a shared protection algorithm(SDS-SDP). Block probabilities of the algorithms are assessed through simulation. Simulation results show that, in most cases, block probability of SDS-SDP is lowest since SDS-SDP shares protecting wavelengths among connection requests. When the network load is light, SDP-DP has lowest block probability.
2006, 28(3): 455-460.
Abstract:
Focusing on Turbo-coded dual N-ary orthogonal spread spectrum system, this paper proposes an algorithm for computing bit soft metric based on Maximum a Posteriori Probability (MAP) criterion, and then presents a simplified MAP algorithm. Meanwhile, the fixed-point and float-point performances are simulated and compared with several existing algorithms. It is shown that MAP algorithm greatly improves the whole system performance; the simplified MAP algorithm with L=3 outperforms the dual-maxima algorithms 0.4dB without extra cost in complexity..
Focusing on Turbo-coded dual N-ary orthogonal spread spectrum system, this paper proposes an algorithm for computing bit soft metric based on Maximum a Posteriori Probability (MAP) criterion, and then presents a simplified MAP algorithm. Meanwhile, the fixed-point and float-point performances are simulated and compared with several existing algorithms. It is shown that MAP algorithm greatly improves the whole system performance; the simplified MAP algorithm with L=3 outperforms the dual-maxima algorithms 0.4dB without extra cost in complexity..
Narrow-Band Interference Suppression in Transform Domain
Based on Adaptive Multi-threshold Algorithm
2006, 28(3): 461-465.
Abstract:
This paper studies the narrowband interference suppression algorithm based on threshold detection in transform domain, and a novel adaptive multi-threshold narrowband interference detection algorithm is proposed. Theoretical analysis and simulations prove that this algorithm has good performance in suppressing the narrowband interference in DSSS signal.
This paper studies the narrowband interference suppression algorithm based on threshold detection in transform domain, and a novel adaptive multi-threshold narrowband interference detection algorithm is proposed. Theoretical analysis and simulations prove that this algorithm has good performance in suppressing the narrowband interference in DSSS signal.
2006, 28(3): 466-470.
Abstract:
The proposed new fusion algorithm is based on the improved Pulse Coupled Neural network(PCNN) model, the fundamental characteristics of multi-focus images and the properties of human vision system. Compared with the traditional algorithm where the linking strength of each neuron is the same and its value is chosen through experimentation, this algorithm uses the sharpness of each pixel as its value, so that the linking strength of each pixel can be chosen adaptively. After the processing of PCNN with the adaptive linking strength, new fire mapping images are obtained for each image taking part in the fusion. The clear objects of each original image are decided by the compare-selection operator with the fire mapping images pixel by pixel and then all of them are merged into a new clear image. Furthermore, by this algorithm, other parameters, for example, , the threshold adjusting constant, only have a slight effect on the new fused image. It therefore overcomes the difficulty in adjusting parameters in PCNN. Experiments show that the proposed algorithm works better in preserving the edge and texture information than the wavelet transform method and the Laplacian pyramid method do in multi-focus image fusion.
The proposed new fusion algorithm is based on the improved Pulse Coupled Neural network(PCNN) model, the fundamental characteristics of multi-focus images and the properties of human vision system. Compared with the traditional algorithm where the linking strength of each neuron is the same and its value is chosen through experimentation, this algorithm uses the sharpness of each pixel as its value, so that the linking strength of each pixel can be chosen adaptively. After the processing of PCNN with the adaptive linking strength, new fire mapping images are obtained for each image taking part in the fusion. The clear objects of each original image are decided by the compare-selection operator with the fire mapping images pixel by pixel and then all of them are merged into a new clear image. Furthermore, by this algorithm, other parameters, for example, , the threshold adjusting constant, only have a slight effect on the new fused image. It therefore overcomes the difficulty in adjusting parameters in PCNN. Experiments show that the proposed algorithm works better in preserving the edge and texture information than the wavelet transform method and the Laplacian pyramid method do in multi-focus image fusion.
2006, 28(3): 471-475.
Abstract:
In this paper, a kind of new Independent Component Analysis (ICA) method based on 2-dimensional wavelet transform is proposed. According to the research, the steady-state error of the Natural Gradient Algorithm (NGA) is inverse proportional to the quadratic of the kurtosis of the sources when the probability distribution function of each source is the same. In addition, the kurtosis of the detail coefficients in wavelet domain is always bigger than that of the original images, so the separation precision of ICA method based on 2-dimensional wavelet transform is higher than that of the traditional ICA method. Furthermore, the size of the sub-image in 2-dimensional wavelet domain is a quarter of the source image, so the convergence speed of the proposed method is faster. Finally, this method is used to separate the mixed images. A set of experiments in different situations is done and the simulation results show that the proposed method is effective.
In this paper, a kind of new Independent Component Analysis (ICA) method based on 2-dimensional wavelet transform is proposed. According to the research, the steady-state error of the Natural Gradient Algorithm (NGA) is inverse proportional to the quadratic of the kurtosis of the sources when the probability distribution function of each source is the same. In addition, the kurtosis of the detail coefficients in wavelet domain is always bigger than that of the original images, so the separation precision of ICA method based on 2-dimensional wavelet transform is higher than that of the traditional ICA method. Furthermore, the size of the sub-image in 2-dimensional wavelet domain is a quarter of the source image, so the convergence speed of the proposed method is faster. Finally, this method is used to separate the mixed images. A set of experiments in different situations is done and the simulation results show that the proposed method is effective.
2006, 28(3): 476-479.
Abstract:
The vector hydrophone is composed of three spatially co-located but orthogonal oriented velocity hydrophone plus another co-located pressure hydrophone. To understand the performance of DOA estimation using vector hydrophone array in a reflecting boundary, based on the reflecting model of plan acoustic wave, the improved Bartlett and Capon spatial spectrum are presented, and then the general frame is set up. The ability of DOA estimation using vector hydrophone array is also compared with that of pressure hydrophone array in rigid boundary. Finally numerical experimentatal results show its validity.
The vector hydrophone is composed of three spatially co-located but orthogonal oriented velocity hydrophone plus another co-located pressure hydrophone. To understand the performance of DOA estimation using vector hydrophone array in a reflecting boundary, based on the reflecting model of plan acoustic wave, the improved Bartlett and Capon spatial spectrum are presented, and then the general frame is set up. The ability of DOA estimation using vector hydrophone array is also compared with that of pressure hydrophone array in rigid boundary. Finally numerical experimentatal results show its validity.
2006, 28(3): 480-484.
Abstract:
The performance of the speech recognition systems is deteriorated dramatically under noise condition for variation of speech signal. According to the auditory tests, this paper proposes a new nonlinear sub-band Maximum A Posteriori (MAP)statistical matching algorithm based on the independent sub-band analysis. According to the perception of humans ear and noise feature of different frequency-bands, the algorithm compensates the effects of noise with statistical matching, MAP estimation and HMM/MLP nonlinear mapping. The test shows that the proposed algorithm improves the recognition performance notably under noise condition.
The performance of the speech recognition systems is deteriorated dramatically under noise condition for variation of speech signal. According to the auditory tests, this paper proposes a new nonlinear sub-band Maximum A Posteriori (MAP)statistical matching algorithm based on the independent sub-band analysis. According to the perception of humans ear and noise feature of different frequency-bands, the algorithm compensates the effects of noise with statistical matching, MAP estimation and HMM/MLP nonlinear mapping. The test shows that the proposed algorithm improves the recognition performance notably under noise condition.
2006, 28(3): 485-489.
Abstract:
A method for watershed image segmentation based on morphological scale-space and gradient modification is proposed to avoid over-segmentation and the drawbacks of some improved watershed segmentations. Firstly, morphological hybrid opening and closing by reconstruction scale-space is employed to smooth the original image, after smoothing, the essential region contours are preserved and unimportant details and noise which are often the causes of over-segmentation are removed, and the problem of the traditional morphological opening and closing scale-space, including the lost of partial essential region contours and not satisfying scale causality, are both avoided. Secondly, in order to eliminate over-segmentation and to keep the scale causality from the extreme to the segmented regions, gradient modification is used before the standard watershed transform, to remove the regional minimum in the gradient image caused by the regional maximum in the smoothed image. Simulations show that this method can efficiently not only avoid over-segmentation, but also satisfy scale causality, and the localization of region contours is precise.
A method for watershed image segmentation based on morphological scale-space and gradient modification is proposed to avoid over-segmentation and the drawbacks of some improved watershed segmentations. Firstly, morphological hybrid opening and closing by reconstruction scale-space is employed to smooth the original image, after smoothing, the essential region contours are preserved and unimportant details and noise which are often the causes of over-segmentation are removed, and the problem of the traditional morphological opening and closing scale-space, including the lost of partial essential region contours and not satisfying scale causality, are both avoided. Secondly, in order to eliminate over-segmentation and to keep the scale causality from the extreme to the segmented regions, gradient modification is used before the standard watershed transform, to remove the regional minimum in the gradient image caused by the regional maximum in the smoothed image. Simulations show that this method can efficiently not only avoid over-segmentation, but also satisfy scale causality, and the localization of region contours is precise.
2006, 28(3): 490-494.
Abstract:
A new approach based on two-dimensional Gabor wavelets transform for face recognition is presented. The Gabor wavelet representation of an image is the convolution of the image with a family of Gabor kernels. A set of vectors called nodes, over a dense grid of image points are formed, and each node is labeled with a set of complex Gabor wavelets coefficients. The magnitudes of the coefficients are used for recognition. Principal component analysis is a decorrelation technique and its primary goal is to project the high dimensional vectors into a lower dimensional space. Feature nodes, as observation vectors of HMM, is derived by using principal component analysis. A set of images representing different instances of the same person is used to train each HMM, and each individual in the database is represented by an optimal HMM face model. Experimental results show that the proposed algorithm has a high recognition rate with relatively low complexity.
A new approach based on two-dimensional Gabor wavelets transform for face recognition is presented. The Gabor wavelet representation of an image is the convolution of the image with a family of Gabor kernels. A set of vectors called nodes, over a dense grid of image points are formed, and each node is labeled with a set of complex Gabor wavelets coefficients. The magnitudes of the coefficients are used for recognition. Principal component analysis is a decorrelation technique and its primary goal is to project the high dimensional vectors into a lower dimensional space. Feature nodes, as observation vectors of HMM, is derived by using principal component analysis. A set of images representing different instances of the same person is used to train each HMM, and each individual in the database is represented by an optimal HMM face model. Experimental results show that the proposed algorithm has a high recognition rate with relatively low complexity.
2006, 28(3): 495-497.
Abstract:
Detail entropy is proposed which can indicate the image clarity much accurately in the case of that image has slowly changed part. A technique based on detail entropy minimization principle is developed for fusing netted radar data. For complex radar target, the weights are calculated iteratively. But in consider of real-time requirement, the weights are gotten by neural network alternatively.
Detail entropy is proposed which can indicate the image clarity much accurately in the case of that image has slowly changed part. A technique based on detail entropy minimization principle is developed for fusing netted radar data. For complex radar target, the weights are calculated iteratively. But in consider of real-time requirement, the weights are gotten by neural network alternatively.
2006, 28(3): 498-501.
Abstract:
The optimal polarization filtering is investigated, which can be described as optimization with a nonlinear restriction. The nonlinear restriction is removed through an intermediary variable. According to the extremum necessary condition, the optimization is further transformed into problem of rooting a unitary quadratic equation. Consequently, the maximal SINR is the bigger root of the unitary quadratic equation and the optimal receiving polarization is obtained. The filtering performance is improved with the difference increasing in polarization domains between the desired signal and interference. The completely polarized interference can be suppressed easily and the partially polarized interference is difficult. to be suppressed.
The optimal polarization filtering is investigated, which can be described as optimization with a nonlinear restriction. The nonlinear restriction is removed through an intermediary variable. According to the extremum necessary condition, the optimization is further transformed into problem of rooting a unitary quadratic equation. Consequently, the maximal SINR is the bigger root of the unitary quadratic equation and the optimal receiving polarization is obtained. The filtering performance is improved with the difference increasing in polarization domains between the desired signal and interference. The completely polarized interference can be suppressed easily and the partially polarized interference is difficult. to be suppressed.
2006, 28(3): 502-506.
Abstract:
This paper studies image algorithms and analyses imaging quality of air-borne Synthetic Aperture Radar (SAR) in large squint mode. Based on the spatial geometry model of squint mode air-borne SAR and echo response, a method to improve RD algorithm is introduced in detail, and the flowcharts of this algorithm and Extended Chirp Scaling (ECS) algorithm are given. The simulation results demonstrate that these two algorithms meet the requirements of air-borne SAR imaging in large squint mode.
This paper studies image algorithms and analyses imaging quality of air-borne Synthetic Aperture Radar (SAR) in large squint mode. Based on the spatial geometry model of squint mode air-borne SAR and echo response, a method to improve RD algorithm is introduced in detail, and the flowcharts of this algorithm and Extended Chirp Scaling (ECS) algorithm are given. The simulation results demonstrate that these two algorithms meet the requirements of air-borne SAR imaging in large squint mode.
2006, 28(3): 507-511.
Abstract:
This paper presents a new SAR raw data compression algorithm named Normalized Adaptive Predictive Vector Quantization (NAPVQ). The normalized SAR raw data are firstly processed with vector linear predictor, and then the error vectors are compressed with vector quantizer. Regarded as an extension of the differential pulse code modulation in the vector quantization, the NAPVQ achieves a better performance gain than the Block Adaptive Vector Quantization (BAVQ) and the Normalized Predictive Adaptive Quantization (NPAQ). With the analyses of algorithm complexity, the proposed algorithm shows a good performance/complexity trade-off and accommodates the requirement in engineering applications.
This paper presents a new SAR raw data compression algorithm named Normalized Adaptive Predictive Vector Quantization (NAPVQ). The normalized SAR raw data are firstly processed with vector linear predictor, and then the error vectors are compressed with vector quantizer. Regarded as an extension of the differential pulse code modulation in the vector quantization, the NAPVQ achieves a better performance gain than the Block Adaptive Vector Quantization (BAVQ) and the Normalized Predictive Adaptive Quantization (NPAQ). With the analyses of algorithm complexity, the proposed algorithm shows a good performance/complexity trade-off and accommodates the requirement in engineering applications.
2006, 28(3): 512-516.
Abstract:
In this paper, the ambiguity function is defined and derived from the character of formation flying satellites SAR. The results of the computer simulations demonstrate the efficacy of the proposed function. Further, by analyzing the ambiguity function, it is clear to demonstrate the influence of satellites configuration on the system resolution, which provides principle for the selection of satellites configuration.
In this paper, the ambiguity function is defined and derived from the character of formation flying satellites SAR. The results of the computer simulations demonstrate the efficacy of the proposed function. Further, by analyzing the ambiguity function, it is clear to demonstrate the influence of satellites configuration on the system resolution, which provides principle for the selection of satellites configuration.
2006, 28(3): 517-521.
Abstract:
For the polarimetric and high-resolution radar system, a novel method is proposed, where the polarization and high resolution range profile are integrated for radar target recognition. The physical-statistical non-Gaussian model is used to model for polarimetric high resolution range profile. The model parameters describe the scattering physical characteristics of radar target and are adopted as feature vector for radar target recognition. Furthermore, Parzen window is used to estimate the probability distribution function of model parameter and the classifier is designed via Bayes theorem. The method is applied to the classification of several kinds of missile. Numerical eresults have shown that the method can extract the features which are independent to target orientation and are effective to radar target recognition.
For the polarimetric and high-resolution radar system, a novel method is proposed, where the polarization and high resolution range profile are integrated for radar target recognition. The physical-statistical non-Gaussian model is used to model for polarimetric high resolution range profile. The model parameters describe the scattering physical characteristics of radar target and are adopted as feature vector for radar target recognition. Furthermore, Parzen window is used to estimate the probability distribution function of model parameter and the classifier is designed via Bayes theorem. The method is applied to the classification of several kinds of missile. Numerical eresults have shown that the method can extract the features which are independent to target orientation and are effective to radar target recognition.
2006, 28(3): 522-525.
Abstract:
Distributed satellites bistatic SAR can be considered as a kind of bistatic/multi-static SAR system, whose transmitters and receivers move in parallel. Based on this, in this paper, the geometry resolution of distributed satellites SAR is analyzed using the concept of gradient. The formulas of resolution characteristics, such as geometry resolution, the direction of resolution vector and the area of resolution cell, are deduced in the form of look angle and squint angles functions. In addition, the influence of satellites baselines on the geometry resolution is also discussed, and the simulated results are also provided here.
Distributed satellites bistatic SAR can be considered as a kind of bistatic/multi-static SAR system, whose transmitters and receivers move in parallel. Based on this, in this paper, the geometry resolution of distributed satellites SAR is analyzed using the concept of gradient. The formulas of resolution characteristics, such as geometry resolution, the direction of resolution vector and the area of resolution cell, are deduced in the form of look angle and squint angles functions. In addition, the influence of satellites baselines on the geometry resolution is also discussed, and the simulated results are also provided here.
2006, 28(3): 526-531.
Abstract:
In this paper, a new technique about long distance source localization with passive synthetic aperture sonar array is presented. At first, a sound field receiving equation for synthetic aperture sonar is derived. Then, this new method is described in detail that obtains a long distant passive azimuth, range and depth source localization by the normal-mode filter and the large synthetic aperture through horizontal moving of a short line array. The simulated results indicate that the estimation of accuracy in azimuth and range source localization is improved by this method. In addition, it is certificated that the passive synthetic aperture sonar array can realize effectively long distant source localization by normal-mode filtering method.
In this paper, a new technique about long distance source localization with passive synthetic aperture sonar array is presented. At first, a sound field receiving equation for synthetic aperture sonar is derived. Then, this new method is described in detail that obtains a long distant passive azimuth, range and depth source localization by the normal-mode filter and the large synthetic aperture through horizontal moving of a short line array. The simulated results indicate that the estimation of accuracy in azimuth and range source localization is improved by this method. In addition, it is certificated that the passive synthetic aperture sonar array can realize effectively long distant source localization by normal-mode filtering method.
2006, 28(3): 532-536.
Abstract:
For the shortage of plan recognition method presented by Kautz(1987) in controlling mechanism, a plan recognition method based on planning knowledge graph is discussed in detail. Using first-order predicate logic as formal language, an instance of tactical intelligent planning is analyzed and a situation assessment model combined tactical intelligent planning system and a tactical plan recognition system are proposed. The plan library, which is dynamic set up, could break through the limit of closed world hypothesis in Kautzs plan recognition method. The model is capable of supplying reasonable hypothesis for enemys action goal and plan and projecting enemys future action, which is helpful to command decision.
For the shortage of plan recognition method presented by Kautz(1987) in controlling mechanism, a plan recognition method based on planning knowledge graph is discussed in detail. Using first-order predicate logic as formal language, an instance of tactical intelligent planning is analyzed and a situation assessment model combined tactical intelligent planning system and a tactical plan recognition system are proposed. The plan library, which is dynamic set up, could break through the limit of closed world hypothesis in Kautzs plan recognition method. The model is capable of supplying reasonable hypothesis for enemys action goal and plan and projecting enemys future action, which is helpful to command decision.
2006, 28(3): 537-541.
Abstract:
This paper presents a quantum public-key cryptosystem by using quantum Calderbank-Shor-Steane(CSS) error correcting codes and the NPC problem related with decoding general linear codes. It uses classical key to encrypt quantum message, and its security relies on the fact that NPC problem can not be solved on quantum Turing machines. Based on this public-key cryptosystem, this paper also gives a message authentication scheme and proves its security.
This paper presents a quantum public-key cryptosystem by using quantum Calderbank-Shor-Steane(CSS) error correcting codes and the NPC problem related with decoding general linear codes. It uses classical key to encrypt quantum message, and its security relies on the fact that NPC problem can not be solved on quantum Turing machines. Based on this public-key cryptosystem, this paper also gives a message authentication scheme and proves its security.
2006, 28(3): 542-545.
Abstract:
Further research on the construction of public-key cryptosystem based on Linear Feedback Shift Register (LFSR) is provided, and the LFSR higher (non) residuosity problem is defined. Based on new intractability problems a new public-key encryption primitive with encryption/decryption procedures differ from GH is investigated. The encryption and decryption procedures are specified. It is further improved to be a probabilistic encryption scheme. Efficiency and security analysis of the proposed encryption scheme is provided. It has properties of one-wayness and semantic security. The one-wayness and semantic security are equivalent to higher LFSR residuosity and decisional LFSR residuosity problems respectively.
Further research on the construction of public-key cryptosystem based on Linear Feedback Shift Register (LFSR) is provided, and the LFSR higher (non) residuosity problem is defined. Based on new intractability problems a new public-key encryption primitive with encryption/decryption procedures differ from GH is investigated. The encryption and decryption procedures are specified. It is further improved to be a probabilistic encryption scheme. Efficiency and security analysis of the proposed encryption scheme is provided. It has properties of one-wayness and semantic security. The one-wayness and semantic security are equivalent to higher LFSR residuosity and decisional LFSR residuosity problems respectively.
2006, 28(3): 546-550.
Abstract:
Since the introduction of Mobile Agent (MA), security is always an important issue for its restriction to the MAs wide-application. As the extension of distributed Client/Server computing, the present idea of multiple mobile agents gives a new way for increasing the security of the whole mobile agent system. In this paper, problems are firstly discussed in detail when applying the secret splitting scheme based on Lagrange interpolation and the subsequent multiple-signature scheme into Multiple Mobile Agent System (MMAS). Secondly, an improved and more practical scheme for the MMAS is proposed. An e-business case based on this scheme is presented at the end of this paper.
Since the introduction of Mobile Agent (MA), security is always an important issue for its restriction to the MAs wide-application. As the extension of distributed Client/Server computing, the present idea of multiple mobile agents gives a new way for increasing the security of the whole mobile agent system. In this paper, problems are firstly discussed in detail when applying the secret splitting scheme based on Lagrange interpolation and the subsequent multiple-signature scheme into Multiple Mobile Agent System (MMAS). Secondly, an improved and more practical scheme for the MMAS is proposed. An e-business case based on this scheme is presented at the end of this paper.
2006, 28(3): 551-556.
Abstract:
A new method combining the protocol conversion methodology and the Petri nets theory is proposed to study application layer protocol conversion. According to the procedure proposed by the protocol conversion methodology, the Click-To-Dial (CTD) service in the Internet Intelligent Network (IIN) model is analyzed. From the modeling experiences of CTD service with Petri nets, universal coupling criteria of Petri nets model of protocol conversion are abstracted, which enrich the protocol conversion methodology. Protocol conversion model of CTD service is analyzed with analysis techniques of Petri nets and its errors are checked and corrected. A Service Control Gateway Function (SCGF) and CTD service have been developed under the guide of this new method, which is proved viable and applicable.
A new method combining the protocol conversion methodology and the Petri nets theory is proposed to study application layer protocol conversion. According to the procedure proposed by the protocol conversion methodology, the Click-To-Dial (CTD) service in the Internet Intelligent Network (IIN) model is analyzed. From the modeling experiences of CTD service with Petri nets, universal coupling criteria of Petri nets model of protocol conversion are abstracted, which enrich the protocol conversion methodology. Protocol conversion model of CTD service is analyzed with analysis techniques of Petri nets and its errors are checked and corrected. A Service Control Gateway Function (SCGF) and CTD service have been developed under the guide of this new method, which is proved viable and applicable.
2006, 28(3): 557-561.
Abstract:
QoS supports of multiclass data service in IP network includes generally packet delay, throughput and loss rate, while the majority last research focus on either minimizing packet delay and loss or maximizing user throughput. In this paper, an algorithm DPAA (Dynamic Proportional Adaptive Algorithm) for assuring the difference service under traffic vary-time condition in Proportional Differentiated Services(PDS) model is proposed. The scheme takes into account the throughput, delay and loss rate of packets between classes simultaneously. Simulation indicates that the DPAA has a good performance compared to the previous works.
QoS supports of multiclass data service in IP network includes generally packet delay, throughput and loss rate, while the majority last research focus on either minimizing packet delay and loss or maximizing user throughput. In this paper, an algorithm DPAA (Dynamic Proportional Adaptive Algorithm) for assuring the difference service under traffic vary-time condition in Proportional Differentiated Services(PDS) model is proposed. The scheme takes into account the throughput, delay and loss rate of packets between classes simultaneously. Simulation indicates that the DPAA has a good performance compared to the previous works.
2006, 28(3): 562-566.
Abstract:
Directed diffusion is a classical data propagation protocol for wireless sensor networks. In directed diffusion routing, the diffusion of exploratory data can inevitably lead to heavy traffic periodically. Then the performance of data propagation may severely deteriorate at that moment. A gradient-based constrained diffusion algorithm is proposed in this paper. By analyzing the gradients of nodes neighbors, the breadth and depth for diffusion can be conducted firstly. Then diffusion is performed in the optimal set of selected forwarding nodes. The simulation results indicate that this algorithm can decrease both duration of diffusion and propagation delay greatly. In addition, it is energy-efficient, and compatible with existing algorithm without additional cost of control message.
Directed diffusion is a classical data propagation protocol for wireless sensor networks. In directed diffusion routing, the diffusion of exploratory data can inevitably lead to heavy traffic periodically. Then the performance of data propagation may severely deteriorate at that moment. A gradient-based constrained diffusion algorithm is proposed in this paper. By analyzing the gradients of nodes neighbors, the breadth and depth for diffusion can be conducted firstly. Then diffusion is performed in the optimal set of selected forwarding nodes. The simulation results indicate that this algorithm can decrease both duration of diffusion and propagation delay greatly. In addition, it is energy-efficient, and compatible with existing algorithm without additional cost of control message.
2006, 28(3): 567-569.
Abstract:
Aiming at the uneven routing results and much noise, this paper presents an improved method for multichip module routing that based on the four-via routing algorithm. By using the PST(Priority Search Tree) and LEA(Left Edge Algorithm) algorithms to restrict routing layers, remove vias or jogs and reduce noise, the result is optimized. The computer simulation results show that routing space is efficiently utilized and the delay and noise are also reduced in the field of electric feature.
Aiming at the uneven routing results and much noise, this paper presents an improved method for multichip module routing that based on the four-via routing algorithm. By using the PST(Priority Search Tree) and LEA(Left Edge Algorithm) algorithms to restrict routing layers, remove vias or jogs and reduce noise, the result is optimized. The computer simulation results show that routing space is efficiently utilized and the delay and noise are also reduced in the field of electric feature.
2006, 28(3): 570-573.
Abstract:
Mobile Ad hoc NETworks (MANET) are an ideal technology in future civilian and military applications and it will become necessary to communicate across MANET and the wired Internet. In this paper, It is investigated that the effect of some key issues, such as hidden terminal and exposed terminal of gateway, the speed of the wireless nodes, the number of flows, on TCP performance in the static and dynamic wired/wireless scenarios. This paper will prove very valuable to future commercial and military wired/MANET networks.
Mobile Ad hoc NETworks (MANET) are an ideal technology in future civilian and military applications and it will become necessary to communicate across MANET and the wired Internet. In this paper, It is investigated that the effect of some key issues, such as hidden terminal and exposed terminal of gateway, the speed of the wireless nodes, the number of flows, on TCP performance in the static and dynamic wired/wireless scenarios. This paper will prove very valuable to future commercial and military wired/MANET networks.
2006, 28(3): 574-576.
Abstract:
As the velocity of signal switch becoming fast, the crosstalk in high-speed circuit design is becoming worse than ever. The performance of guard traces in reducing the crosstalk between microstrips is analyzed and simulated with FDTD method in this paper. The simulation results show that the far-end and near-end crosstalks are reduced largely and efficiently by the following useful measures: (1) The guard trace with several grounded vias should be inserted between microstrips and the distance between two adjacent vias should be less than propagating distance during RT/2, the half rising time of signal. (2) By obeying the smallest side-to-side distance routing rule and keeping the center-to-center distances between arbitrary two of three lines (microstrips and the guard trace) constant, the guard trace inserted should be as wide as possible.
As the velocity of signal switch becoming fast, the crosstalk in high-speed circuit design is becoming worse than ever. The performance of guard traces in reducing the crosstalk between microstrips is analyzed and simulated with FDTD method in this paper. The simulation results show that the far-end and near-end crosstalks are reduced largely and efficiently by the following useful measures: (1) The guard trace with several grounded vias should be inserted between microstrips and the distance between two adjacent vias should be less than propagating distance during RT/2, the half rising time of signal. (2) By obeying the smallest side-to-side distance routing rule and keeping the center-to-center distances between arbitrary two of three lines (microstrips and the guard trace) constant, the guard trace inserted should be as wide as possible.
