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2011 Vol. 33, No. 5
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2011, 33(5): 1017-1023.
doi: 10.3724/SP.J.1146.2010.00805
Abstract:
In order to improve the performance of motion estimation in video encoding, a biogeography-based optimization algorithm is proposed for fast motion estimation. Based on the characteristic of motion vector, the method used the migration and mutation of Biogeography-Based Optimization (BBO) to search global optimum and overcame the shortcoming of falling into local optimum in existing fast block-matching algorithms. Meanwhile, it adopted early and iterative termination strategy to further simplify computational complexity. Experimental results show that it has higher efficiency than the existing fast algorithms in terms of search accuracy and speed. Because of simple and practicality, it is feasible for real-time video encoding.
In order to improve the performance of motion estimation in video encoding, a biogeography-based optimization algorithm is proposed for fast motion estimation. Based on the characteristic of motion vector, the method used the migration and mutation of Biogeography-Based Optimization (BBO) to search global optimum and overcame the shortcoming of falling into local optimum in existing fast block-matching algorithms. Meanwhile, it adopted early and iterative termination strategy to further simplify computational complexity. Experimental results show that it has higher efficiency than the existing fast algorithms in terms of search accuracy and speed. Because of simple and practicality, it is feasible for real-time video encoding.
2011, 33(5): 1024-1029.
doi: 10.3724/SP.J.1146.2010.00912
Abstract:
Based on the flutter characteristic of smoke, a novel video smoke detection algorithm is proposed. Firstly, the motion region is detected from video frames. Then four flutter features of the motion region are extracted over a sliding time window, including the flutter direction and three types of flutter intensities. Finally, the neuro-fuzzy inference system is used to detect smoke, in which fuzzy rules and membership functions are trained according to the valid sample set. Experimental results show that the new algorithm has excellent performance on Receiver Operating Characteristic (ROC) curve which is very important for real application.
Based on the flutter characteristic of smoke, a novel video smoke detection algorithm is proposed. Firstly, the motion region is detected from video frames. Then four flutter features of the motion region are extracted over a sliding time window, including the flutter direction and three types of flutter intensities. Finally, the neuro-fuzzy inference system is used to detect smoke, in which fuzzy rules and membership functions are trained according to the valid sample set. Experimental results show that the new algorithm has excellent performance on Receiver Operating Characteristic (ROC) curve which is very important for real application.
2011, 33(5): 1030-1034.
doi: 10.3724/SP.J.1146.2010.01007
Abstract:
A video hashing based on Locally Linear Embedding (LLE) is proposed in this paper. In this method, some representative frames are first selected based on a graph model, and four-order cumulants are taken as features of video in the high dimensional feature space. Then the video is mapped to a three-dimensional space using LLE, and video hash sequence is generated using the norms of points in the three-dimensional space to detect video copies. Experimental results show that the video hashing has good robustness and discrimination.
A video hashing based on Locally Linear Embedding (LLE) is proposed in this paper. In this method, some representative frames are first selected based on a graph model, and four-order cumulants are taken as features of video in the high dimensional feature space. Then the video is mapped to a three-dimensional space using LLE, and video hash sequence is generated using the norms of points in the three-dimensional space to detect video copies. Experimental results show that the video hashing has good robustness and discrimination.
2011, 33(5): 1035-1041.
doi: 10.3724/SP.J.1146.2010.01024
Abstract:
This paper proposes a quantum genetic algorithm based on spheral solution space multi-region division. It introduces multi-region parallel searching mechanism with a permutation policy among sub-swarms, designs a novel quantum mutation operator using a variable probability decided by the extend of devolution. It is proved that this algorithm can converge to a global optimal solution with probability 1. The experiments of combinatorial and continuous optimization issue show that the proposed algorithm accelerates the convergence to the expected value smoothly, reducing the probability of premature. It performs well comparatively.
This paper proposes a quantum genetic algorithm based on spheral solution space multi-region division. It introduces multi-region parallel searching mechanism with a permutation policy among sub-swarms, designs a novel quantum mutation operator using a variable probability decided by the extend of devolution. It is proved that this algorithm can converge to a global optimal solution with probability 1. The experiments of combinatorial and continuous optimization issue show that the proposed algorithm accelerates the convergence to the expected value smoothly, reducing the probability of premature. It performs well comparatively.
2011, 33(5): 1042-1048.
doi: 10.3724/SP.J.1146.2010.00902
Abstract:
How to construct compact and powerful feature descriptors is an important research subject in the fields of machine vision and pattern recognition. To tackle the issue that the Haar descriptor of Speeded Up Robust Features (SURF) algorithm can not make full use of the information around the neighborhood of the feature points, this paper proposes a novel local invariant descriptor, called Windowed Intensity Difference Histogram (WIDH). Based on the small core region centered at a feature point, WIDH exploits the intensity difference information within the operating region by sliding the window template, and constructs a simple but discriminative description vector with high computational performance. The experimental results show that the improved SURF with WIDH can obtain comparable or better discriminative power with lower dimensionality, contrast to its original version embedded with Haar wavelets descriptor. In particular, WIDH outperforms its counterpart obviously in the presence of image blurring and noise disturbance, and the recalls of WIDH are upgraded as much as 35% and 50% respectively, with respect to the same false rates.
How to construct compact and powerful feature descriptors is an important research subject in the fields of machine vision and pattern recognition. To tackle the issue that the Haar descriptor of Speeded Up Robust Features (SURF) algorithm can not make full use of the information around the neighborhood of the feature points, this paper proposes a novel local invariant descriptor, called Windowed Intensity Difference Histogram (WIDH). Based on the small core region centered at a feature point, WIDH exploits the intensity difference information within the operating region by sliding the window template, and constructs a simple but discriminative description vector with high computational performance. The experimental results show that the improved SURF with WIDH can obtain comparable or better discriminative power with lower dimensionality, contrast to its original version embedded with Haar wavelets descriptor. In particular, WIDH outperforms its counterpart obviously in the presence of image blurring and noise disturbance, and the recalls of WIDH are upgraded as much as 35% and 50% respectively, with respect to the same false rates.
2011, 33(5): 1049-1054.
doi: 10.3724/SP.J.1146.2010.01044
Abstract:
To extract nonlinear patterns, preserve the manifold structure, and reduce the projection time, a Fast Kernel Supervised Locality Preserving Projection (FKSLPP) algorithm is proposed. This new algorithm firstly selects a subset of the training set by supervised cluster selection algorithm to do Subset Kernel Principal Component Analysis (SKPCA), and then Supervised Locality Preserving Projection (SLPP) is performed in SKPCA subspace. Experiments results show that compared with SLPP and some other popular feature extraction algorithms, FKSLPP can get higher recognition rates; compared with kernel projection algorithms of state of art, FKSLPP is much faster. In some datasets, FKSLPP can get same or higher recognition rates while costs only one-tenth processing time of the common kernel projection algorithms.
To extract nonlinear patterns, preserve the manifold structure, and reduce the projection time, a Fast Kernel Supervised Locality Preserving Projection (FKSLPP) algorithm is proposed. This new algorithm firstly selects a subset of the training set by supervised cluster selection algorithm to do Subset Kernel Principal Component Analysis (SKPCA), and then Supervised Locality Preserving Projection (SLPP) is performed in SKPCA subspace. Experiments results show that compared with SLPP and some other popular feature extraction algorithms, FKSLPP can get higher recognition rates; compared with kernel projection algorithms of state of art, FKSLPP is much faster. In some datasets, FKSLPP can get same or higher recognition rates while costs only one-tenth processing time of the common kernel projection algorithms.
2011, 33(5): 1055-1061.
doi: 10.3724/SP.J.1146.2010.00896
Abstract:
In this paper, a novel maximal margin Support Vector Machine with Magnetic Field effect (MFSVM) is proposed in allusion to the improvement of the generalization performance of pattern classification issue. By introducing a minimum q-magnetic field tape, the basic idea of MFSVM is to find an optimal hyper-plane with magnetic field effect such that one class (or normal patterns) can be enclosed in the q-magnetic field tape due to the magnetic attractive effect, while at the same time the margin between the q-magnetic field tape and the other class (or abnormal patterns) is as large as possible due to magnetic repulsion, thus implementing both maximum between-class margin and minimum within-class volume so as to improve the generalization capability of the proposed method. Experimental results obtained with benchmarking and synthetic datasets show that the proposed algorithm is effective and competitive to other related methods in such cases as two-class and one-class pattern classification respectively.
In this paper, a novel maximal margin Support Vector Machine with Magnetic Field effect (MFSVM) is proposed in allusion to the improvement of the generalization performance of pattern classification issue. By introducing a minimum q-magnetic field tape, the basic idea of MFSVM is to find an optimal hyper-plane with magnetic field effect such that one class (or normal patterns) can be enclosed in the q-magnetic field tape due to the magnetic attractive effect, while at the same time the margin between the q-magnetic field tape and the other class (or abnormal patterns) is as large as possible due to magnetic repulsion, thus implementing both maximum between-class margin and minimum within-class volume so as to improve the generalization capability of the proposed method. Experimental results obtained with benchmarking and synthetic datasets show that the proposed algorithm is effective and competitive to other related methods in such cases as two-class and one-class pattern classification respectively.
2011, 33(5): 1062-1068.
doi: 10.3724/SP.J.1146.2010.00965
Abstract:
Automatic objects recognition is a key issue in image processing area. A new hierarchical objects semantic graph based hybrid learning method is proposed to recognize targets in complicated images. This method builds a hierarchical semantic graph model to reinforce the semantic constraints among targets, background, and components in images. And it also proposes a belief objects network to improve the utilization of spatial information, by using local classifier to calculate objects properties and using belief messages to propagate the objects relationships. Besides, the method uses discriminative learning and generative learning interleavely to improve the training error, memory usage and recognition efficiency. Experimental results demonstrate that the proposed method is meaningful and helpful for image understanding.
Automatic objects recognition is a key issue in image processing area. A new hierarchical objects semantic graph based hybrid learning method is proposed to recognize targets in complicated images. This method builds a hierarchical semantic graph model to reinforce the semantic constraints among targets, background, and components in images. And it also proposes a belief objects network to improve the utilization of spatial information, by using local classifier to calculate objects properties and using belief messages to propagate the objects relationships. Besides, the method uses discriminative learning and generative learning interleavely to improve the training error, memory usage and recognition efficiency. Experimental results demonstrate that the proposed method is meaningful and helpful for image understanding.
2011, 33(5): 1069-1075.
doi: 10.3724/SP.J.1146.2010.00793
Abstract:
Due to the requirement for real-time image processing in optical imaging homing weapon systems, this paper proposes a hardware acceleration based connected-component labeling algorithm, which is a real time and two-pass algorithm. The algorithm integrates the merit of pixel-based and the run-based algorithm, which sets pixel as scan unit and line as label unit. Tree-shape topology is constructed in the first scan process, and lines are exported as the results. Then the labels are replaced in the second scan process to complete the connected-component labeling. Experiments on DSP+FPGA platform demonstrate that the hardware acceleration implementation of algorithm reaches a higher performance and efficiency with less resources consumption, and meet the demand of real-time processing.
Due to the requirement for real-time image processing in optical imaging homing weapon systems, this paper proposes a hardware acceleration based connected-component labeling algorithm, which is a real time and two-pass algorithm. The algorithm integrates the merit of pixel-based and the run-based algorithm, which sets pixel as scan unit and line as label unit. Tree-shape topology is constructed in the first scan process, and lines are exported as the results. Then the labels are replaced in the second scan process to complete the connected-component labeling. Experiments on DSP+FPGA platform demonstrate that the hardware acceleration implementation of algorithm reaches a higher performance and efficiency with less resources consumption, and meet the demand of real-time processing.
2011, 33(5): 1076-1081.
doi: 10.3724/SP.J.1146.2010.01052
Abstract:
OQAM/OFDM is a sort of multicarrier signal based on the orthogonal filter bank, and its special generation procedure determines the complexity of cyclic spectral structure. According to the continuous-time baseband model of OQAM/OFDM system, the second-order cyclostationarity of OQAM signals is proved, and the explicit expression of spectral correlation function is derived, meanwhile, the features of Spectral Correlation Function (SCF) for OQAM and the influence of multipath fading channel are investigated. Simulation results sustain the theoretical analysis.
OQAM/OFDM is a sort of multicarrier signal based on the orthogonal filter bank, and its special generation procedure determines the complexity of cyclic spectral structure. According to the continuous-time baseband model of OQAM/OFDM system, the second-order cyclostationarity of OQAM signals is proved, and the explicit expression of spectral correlation function is derived, meanwhile, the features of Spectral Correlation Function (SCF) for OQAM and the influence of multipath fading channel are investigated. Simulation results sustain the theoretical analysis.
A High-resolution Imaging Algorithm for MIMO SAR Based on the Sub-band Synthesis in Frequency Domain
2011, 33(5): 1082-1087.
doi: 10.3724/SP.J.1146.2010.01067
Abstract:
Considering the contradiction between the azimuth resolution and the swath width for the traditional SAR, a MIMO SAR system with multiple-carrier-frequency LFM waveform is researched. The corresponding geometrical?model is built, and the expressions of the echo signals are derived in detail. A novel imaging algorithm based on the sub-band synthetic technology in frequency domain is proposed. This algorithm which integrates the removing of azimuth ambiguities, the synthesis of the sub-band and the CS imaging can realize 2-D high resolution and wide swath simultaneously. And the improved sub-band synthetic algorithm has more efficiency and practicality than the traditional sub-band synthetic algorithms in time frequency domain. The effectiveness of this method is verified with the theoretical analysis and the computer-based simulations.
Considering the contradiction between the azimuth resolution and the swath width for the traditional SAR, a MIMO SAR system with multiple-carrier-frequency LFM waveform is researched. The corresponding geometrical?model is built, and the expressions of the echo signals are derived in detail. A novel imaging algorithm based on the sub-band synthetic technology in frequency domain is proposed. This algorithm which integrates the removing of azimuth ambiguities, the synthesis of the sub-band and the CS imaging can realize 2-D high resolution and wide swath simultaneously. And the improved sub-band synthetic algorithm has more efficiency and practicality than the traditional sub-band synthetic algorithms in time frequency domain. The effectiveness of this method is verified with the theoretical analysis and the computer-based simulations.
2011, 33(5): 1088-1094.
doi: 10.3724/SP.J.1146.2010.00893
Abstract:
Considering the dependencies between the coefficients of Contourlet transform and their parents coefficients, a non-Gaussian bivariate distribution is given, and corresponding nonlinear threshold function is derived from the model using Bayesian estimation theory. Combined nonlogarithmic additive model of SAR image with bivariate threshold function, a novel SAR image despeckling based on bivariate threshold function in Non-Subsampled Contourlet Transform domain (NSCT) is proposed. Experimental results for speckle reduction on amplitude and intensity of SAR images demonstrate that the method holds a good ability of radiometric preservation, the speckle is despeckled well in homogeneous regions, edges and textures of despeckled image are also clear.
Considering the dependencies between the coefficients of Contourlet transform and their parents coefficients, a non-Gaussian bivariate distribution is given, and corresponding nonlinear threshold function is derived from the model using Bayesian estimation theory. Combined nonlogarithmic additive model of SAR image with bivariate threshold function, a novel SAR image despeckling based on bivariate threshold function in Non-Subsampled Contourlet Transform domain (NSCT) is proposed. Experimental results for speckle reduction on amplitude and intensity of SAR images demonstrate that the method holds a good ability of radiometric preservation, the speckle is despeckled well in homogeneous regions, edges and textures of despeckled image are also clear.
2011, 33(5): 1095-1100.
doi: 10.3724/SP.J.1146.2010.00949
Abstract:
Parametric multichannel target detection in heterogeneous environment is studied in this paper, where the disturbances are represented by Vector AutoregRessive (VAR) model with its spatial covariance matrix following complex inverse Wishart distribution with degrees of freedom and mean Q. When Q is unknown, the Neyman-Pearson Parametric Adaptive Matched Filter (NP-PAMF), Bayesian PAMF (B-PAMF) and its normalized version (B-NPAMF) are proposed based on NP detection rule. And when it is known, the maximum a-posteriori PAMF (MAP-PAMF) and its normalized version (MAP-NPAMF) are proposed followed MAP decision rule. It is shown that NP-PAMF and B-PAMF are both dependent onand B-PAMF is convergent to the PAMF when ; B-NPAMF has no relation with and is consistent with the classic NPAMF. In MAP-PAMF, the MAP estimator of the spatial covariance matrix consists of the classic estimator and the prior knowledge, and the weigh of the later is controlled by . Finally, the complex issues and the detection performances are nalyzed, showing that: Bayesian parametric detectors possess good performances and they are better than their normalized counterparts.
Parametric multichannel target detection in heterogeneous environment is studied in this paper, where the disturbances are represented by Vector AutoregRessive (VAR) model with its spatial covariance matrix following complex inverse Wishart distribution with degrees of freedom and mean Q. When Q is unknown, the Neyman-Pearson Parametric Adaptive Matched Filter (NP-PAMF), Bayesian PAMF (B-PAMF) and its normalized version (B-NPAMF) are proposed based on NP detection rule. And when it is known, the maximum a-posteriori PAMF (MAP-PAMF) and its normalized version (MAP-NPAMF) are proposed followed MAP decision rule. It is shown that NP-PAMF and B-PAMF are both dependent onand B-PAMF is convergent to the PAMF when ; B-NPAMF has no relation with and is consistent with the classic NPAMF. In MAP-PAMF, the MAP estimator of the spatial covariance matrix consists of the classic estimator and the prior knowledge, and the weigh of the later is controlled by . Finally, the complex issues and the detection performances are nalyzed, showing that: Bayesian parametric detectors possess good performances and they are better than their normalized counterparts.
2011, 33(5): 1101-1106.
doi: 10.3724/SP.J.1146.2010.00982
Abstract:
Cueing and handoff is the key of IRST and radar cooperatively detective system, but research on handoff method under multi-target scenario is rarely heard. An optimal radar search schedule is proposed under IRST cueing, and influence on performance of handoff caused by disturbed targets is considered. Compared to conclusions gotten under single scenario, the effectiveness of this method is testified by simulation results.
Cueing and handoff is the key of IRST and radar cooperatively detective system, but research on handoff method under multi-target scenario is rarely heard. An optimal radar search schedule is proposed under IRST cueing, and influence on performance of handoff caused by disturbed targets is considered. Compared to conclusions gotten under single scenario, the effectiveness of this method is testified by simulation results.
2011, 33(5): 1107-1113.
doi: 10.3724/SP.J.1146.2010.00928
Abstract:
Considering the issue of huge data rate in DBF-SAR system, the feasibility of one-bit quantization under low signal-to-noise ratio condition is analyzed by two methods. In the first method, each sample of echo is quantized into one bit, while in the second, samples of both echo and range matched filter are quantized into one bit. Theoretical analysis and numerical experiments indicate that, both methods can correctly get the positions and scattering characteristic of targets, and keep the spatial resolutions. However, false targets and high side lobe are generated, and false targets become more obvious with higher SNR. Therefore, one-bit quantization is feasible when single channel echos SNR is lower than 5 dB.
Considering the issue of huge data rate in DBF-SAR system, the feasibility of one-bit quantization under low signal-to-noise ratio condition is analyzed by two methods. In the first method, each sample of echo is quantized into one bit, while in the second, samples of both echo and range matched filter are quantized into one bit. Theoretical analysis and numerical experiments indicate that, both methods can correctly get the positions and scattering characteristic of targets, and keep the spatial resolutions. However, false targets and high side lobe are generated, and false targets become more obvious with higher SNR. Therefore, one-bit quantization is feasible when single channel echos SNR is lower than 5 dB.
2011, 33(5): 1114-1118.
doi: 10.3724/SP.J.1146.2010.00918
Abstract:
The main performance of spaceborne dual-antenna InSAR system in case of flexible baseline oscillation is investigated. Based on the mast motion model, a reduced raw echo signal of the slave antenna is derived under a limited condition. Then, the antenna beam misalignment is analysed and an alignment scheme is proposed. Finally, the oscillation effect on the SAR image resolution and the interferogram coherence is expounded for both the slow and high frequency. In the example of typical system, theoretical analysis and numerical simulation conducted show the result is consistent, which could provide an reference for the system design and application.
The main performance of spaceborne dual-antenna InSAR system in case of flexible baseline oscillation is investigated. Based on the mast motion model, a reduced raw echo signal of the slave antenna is derived under a limited condition. Then, the antenna beam misalignment is analysed and an alignment scheme is proposed. Finally, the oscillation effect on the SAR image resolution and the interferogram coherence is expounded for both the slow and high frequency. In the example of typical system, theoretical analysis and numerical simulation conducted show the result is consistent, which could provide an reference for the system design and application.
2011, 33(5): 1119-1125.
doi: 10.3724/SP.J.1146.2010.00784
Abstract:
This paper studies single phase center multi-beam spaceborne SAR based on intrapulse beamsteering by combining spaceborne Single Phase Center Multi-Beam (SPCMB-SAR) and intrapulse beamsteering in order to reduce large azimuth ambiguity. The principle of digital beamforming for receiving signal process is explored, including azimuth DBF, elevation DBF and two-dimensional DBF. Three kinds of DBF processing methods are proposed, including azimuth DBF first and elevation DBF later, elevation DBF first and azimuth DBF later, and two-dimensional DBF. The primary system parameters are analyzed. Data rate and calculation complexity of the three methods are compared. Simulation results show that all methods are effective. Ambiguity analysis confirms that the SPCMB-SAR system proposed in this paper can reduce range ambiguity and azimuth ambiguity and realize high resolution wide swath SAR imaging effectively.
This paper studies single phase center multi-beam spaceborne SAR based on intrapulse beamsteering by combining spaceborne Single Phase Center Multi-Beam (SPCMB-SAR) and intrapulse beamsteering in order to reduce large azimuth ambiguity. The principle of digital beamforming for receiving signal process is explored, including azimuth DBF, elevation DBF and two-dimensional DBF. Three kinds of DBF processing methods are proposed, including azimuth DBF first and elevation DBF later, elevation DBF first and azimuth DBF later, and two-dimensional DBF. The primary system parameters are analyzed. Data rate and calculation complexity of the three methods are compared. Simulation results show that all methods are effective. Ambiguity analysis confirms that the SPCMB-SAR system proposed in this paper can reduce range ambiguity and azimuth ambiguity and realize high resolution wide swath SAR imaging effectively.
2011, 33(5): 1126-1130.
doi: 10.3724/SP.J.1146.2010.01071
Abstract:
Taking account of the constant modulus characteristic of most interference signals in civil aviation air-to-ground communication, a single-channel optimal constant modulus algorithm is proposed. In this algorithm the amplitude and phase of the constant signal are estimated with nonlinear least squares method. Interference suppression is realized by subtracting the constant modulus signal from the mixed signal. This method has good compatibility with existing communication systems, and the number of channel is not increased. The convergence problem of the adaptive interference suppression can be avoided. Simulation and experimental results are provided to demonstrate the performance of the proposed method.
Taking account of the constant modulus characteristic of most interference signals in civil aviation air-to-ground communication, a single-channel optimal constant modulus algorithm is proposed. In this algorithm the amplitude and phase of the constant signal are estimated with nonlinear least squares method. Interference suppression is realized by subtracting the constant modulus signal from the mixed signal. This method has good compatibility with existing communication systems, and the number of channel is not increased. The convergence problem of the adaptive interference suppression can be avoided. Simulation and experimental results are provided to demonstrate the performance of the proposed method.
2011, 33(5): 1131-1135.
doi: 10.3724/SP.J.1146.2010.01194
Abstract:
The Channel State Information (CSI) is not taken into consideration in Co-ordinate Interleaved Distributed Space-Time Code (CIDSTC) for two-antenna-relays networks. For this issue, CIDSTC based on Phase Rotation (PR-CIDSTC) is proposed, in which relays rotate their transmitted signals with certain angles. Since these angles are designed to minimize Pair Error Probability (PEP), the performance is enhanced. Simulation demonstrates that the proposed scheme provides a 1.5 dB gain at Bit Error Rate (BER) of10-5 over PR-CIDSTC with only 2 bit feedback amount.
The Channel State Information (CSI) is not taken into consideration in Co-ordinate Interleaved Distributed Space-Time Code (CIDSTC) for two-antenna-relays networks. For this issue, CIDSTC based on Phase Rotation (PR-CIDSTC) is proposed, in which relays rotate their transmitted signals with certain angles. Since these angles are designed to minimize Pair Error Probability (PEP), the performance is enhanced. Simulation demonstrates that the proposed scheme provides a 1.5 dB gain at Bit Error Rate (BER) of10-5 over PR-CIDSTC with only 2 bit feedback amount.
2011, 33(5): 1136-1140.
doi: 10.3724/SP.J.1146.2010.00955
Abstract:
Outage probability is an important parameter in wireless communication systems. This paper studies the system outage probability in the Distributed Antenna Systems (DAS). Firstly, this paper establishes a composite channel model which takes into account three factors such as path loss, lognormal shadowing and Rayleigh fading. Based on the established channel model, the Signal-to-Noise Ratio (SNR) of Mobile Station (MS) over a given position is derived. Then, an uplink transmission expression of the outage probability for the MS over a given position is derived by employing the selective combining. Further, considering the distribution of MSs in the cell, a closed-form expression of the system outage probability is obtained. Numerical results show that the closed-form expression of the system uplink outage probability can match with the simulation results very well.
Outage probability is an important parameter in wireless communication systems. This paper studies the system outage probability in the Distributed Antenna Systems (DAS). Firstly, this paper establishes a composite channel model which takes into account three factors such as path loss, lognormal shadowing and Rayleigh fading. Based on the established channel model, the Signal-to-Noise Ratio (SNR) of Mobile Station (MS) over a given position is derived. Then, an uplink transmission expression of the outage probability for the MS over a given position is derived by employing the selective combining. Further, considering the distribution of MSs in the cell, a closed-form expression of the system outage probability is obtained. Numerical results show that the closed-form expression of the system uplink outage probability can match with the simulation results very well.
2011, 33(5): 1141-1146.
doi: 10.3724/SP.J.1146.2010.00985
Abstract:
Focusing on the STBC OFDM system where transmit power of data symbols are spreading on interleaving-grouped subcarriers of each distributed transmit antenna in Rayleigh fading channel, an optimal method for interleaving depth is proposed. According to the number of channel taps and the multi-path delays, the method searches the optimal interleaving depth to minimize the pair-wise error probability. Simulation results in distributed channel which is composed by M.1225 pedestrian test channel A and channel B show that the proposed algorithm has 1.5 dB gain at BER of 10-5 compared to conventional method using BPSK modulation in STBC system with two transmit antennas and one receive antenna.
Focusing on the STBC OFDM system where transmit power of data symbols are spreading on interleaving-grouped subcarriers of each distributed transmit antenna in Rayleigh fading channel, an optimal method for interleaving depth is proposed. According to the number of channel taps and the multi-path delays, the method searches the optimal interleaving depth to minimize the pair-wise error probability. Simulation results in distributed channel which is composed by M.1225 pedestrian test channel A and channel B show that the proposed algorithm has 1.5 dB gain at BER of 10-5 compared to conventional method using BPSK modulation in STBC system with two transmit antennas and one receive antenna.
2011, 33(5): 1147-1153.
doi: 10.3724/SP.J.1146.2010.00934
Abstract:
The joint resource allocation issue in OFDMA systems or relay-based OFDMA systems with proportional fairness constraints is a mixed discrete programming issue including nonlinear equality constraints, which is hard to tackle efficiently and near optimally. In this paper, an algorithms to solve these two non-convex problems are proposed by Lagrangian dual relaxation based on the equivalent forms. The key in the algorithms is the so-called asymptotic strong duality for OFDMA systems. The asymptotic strong duality suggests that it may be possible to devise polynomial time approximation schemes. These algorithms have the computational complexity linear with the number of subcarriers. Numerical results show that the proposed algorithms can be near optimal to the globally optimal solutions.
The joint resource allocation issue in OFDMA systems or relay-based OFDMA systems with proportional fairness constraints is a mixed discrete programming issue including nonlinear equality constraints, which is hard to tackle efficiently and near optimally. In this paper, an algorithms to solve these two non-convex problems are proposed by Lagrangian dual relaxation based on the equivalent forms. The key in the algorithms is the so-called asymptotic strong duality for OFDMA systems. The asymptotic strong duality suggests that it may be possible to devise polynomial time approximation schemes. These algorithms have the computational complexity linear with the number of subcarriers. Numerical results show that the proposed algorithms can be near optimal to the globally optimal solutions.
2011, 33(5): 1154-1158.
doi: 10.3724/SP.J.1146.2010.01073
Abstract:
The Area Averaged Symbol Error Ratio (AASER) for indoor STBC downlink with distributed transmit antennas is derived, considering the effects of path loss, shadow fading and Rician fading. Then optimal antenna location can be obtained by minimizing AASER. Theoretical analyses show that the optimal antennas location is related to the room length, width, height and the height of the mobile station. Simulation results prove the correctness of the theoretical analysis.
The Area Averaged Symbol Error Ratio (AASER) for indoor STBC downlink with distributed transmit antennas is derived, considering the effects of path loss, shadow fading and Rician fading. Then optimal antenna location can be obtained by minimizing AASER. Theoretical analyses show that the optimal antennas location is related to the room length, width, height and the height of the mobile station. Simulation results prove the correctness of the theoretical analysis.
2011, 33(5): 1159-1165.
doi: 10.3724/SP.J.1146.2010.00940
Abstract:
Tag collision in RFID system increases the time overhead and energy consumption of passive tags, reduces the recognition rate. An Uninterrupted anti-collision algorithm with ID-based Grouping (UIG) is proposed. Firstly, it separates tags into different groups resort to the company code and product code. Then, the algorithm generates two initial tag identification codes of each group by the collision information of products serial number. Finally, it identifies all tags via add or decrease 1 of the initial tags. Analysis of performance and the results of simulation show that the proposed algorithm improves the time complexity and communication complexity, the throughput is also greatly improved.
Tag collision in RFID system increases the time overhead and energy consumption of passive tags, reduces the recognition rate. An Uninterrupted anti-collision algorithm with ID-based Grouping (UIG) is proposed. Firstly, it separates tags into different groups resort to the company code and product code. Then, the algorithm generates two initial tag identification codes of each group by the collision information of products serial number. Finally, it identifies all tags via add or decrease 1 of the initial tags. Analysis of performance and the results of simulation show that the proposed algorithm improves the time complexity and communication complexity, the throughput is also greatly improved.
2011, 33(5): 1166-1171.
doi: 10.3724/SP.J.1146.2010.00886
Abstract:
The conventional timing metric based on Pseudo Noise (PN) sequence-weighted preamble for OFDM systems is analyzed, and an adaptive symbol synchronization method is proposed. With the improved preamble, the proposed method uses the repeated property of the cyclic prefix and the distribution property of timing metric based on PN sequence-weighted preamble to design timing scheme, and carries out adaptive symbol synchronization according to the peak value of timing metric in a selected region. Analysis and simulation results show that compared with the conventional symbol synchronization method based on PN sequence-weighted preamble, the proposed method achieves low false detection probability, and improves the estimation performance for symbol synchronization.
The conventional timing metric based on Pseudo Noise (PN) sequence-weighted preamble for OFDM systems is analyzed, and an adaptive symbol synchronization method is proposed. With the improved preamble, the proposed method uses the repeated property of the cyclic prefix and the distribution property of timing metric based on PN sequence-weighted preamble to design timing scheme, and carries out adaptive symbol synchronization according to the peak value of timing metric in a selected region. Analysis and simulation results show that compared with the conventional symbol synchronization method based on PN sequence-weighted preamble, the proposed method achieves low false detection probability, and improves the estimation performance for symbol synchronization.
2011, 33(5): 1172-1177.
doi: 10.3724/SP.J.1146.2010.01051
Abstract:
Traditional cognitive radio employs Opportunistic Spectrum Access (OSA), the quality of cognitive transmission could not be guaranteed. By exploiting the spatial signal processing ability provided by multiple antennas, a Space Division Multiplexing based OSA (SDM-OSA) scheme for cognitive radio networks is proposed. When spectrum holes exist traditional OSA is employed. While there is no idle spectrum available cognitive system utilizes spatial information to implement transmit precoding and receive filtering, so that cognitive transmission is carried out using SDM. Antenna requirements in cognitive system are further discussed. When this demand is met, cognitive transmission could coexist with the primary (licensed) in an occupied authorized frequency channel with mutual interference eliminated. Compared with traditional cognitive radio which employs OSA to utilize the temporally spare frequency resource, the proposed scheme could effectively improve the performance of cognitive system and impose no interference on the primary.
Traditional cognitive radio employs Opportunistic Spectrum Access (OSA), the quality of cognitive transmission could not be guaranteed. By exploiting the spatial signal processing ability provided by multiple antennas, a Space Division Multiplexing based OSA (SDM-OSA) scheme for cognitive radio networks is proposed. When spectrum holes exist traditional OSA is employed. While there is no idle spectrum available cognitive system utilizes spatial information to implement transmit precoding and receive filtering, so that cognitive transmission is carried out using SDM. Antenna requirements in cognitive system are further discussed. When this demand is met, cognitive transmission could coexist with the primary (licensed) in an occupied authorized frequency channel with mutual interference eliminated. Compared with traditional cognitive radio which employs OSA to utilize the temporally spare frequency resource, the proposed scheme could effectively improve the performance of cognitive system and impose no interference on the primary.
2011, 33(5): 1178-1185.
doi: 10.3724/SP.J.1146.2010.00818
Abstract:
Current HandOver (HO) mechanism usually cuts down the duration of service interruption by pre- executing some preparation operations before HO execution. But this technique is much dependant on mobility trace prediction algorithm, which is very difficult in actual environment. To resolve this problem, a novel HO mechanism based on Cooperative Diversity (CDHO) is proposed. CDHO introduces cooperative diversity between Mobile Node (MN) and source Base Station (BS) to extend the service duration in which source BS can satisfy MNs QoS requirement. In this extended duration, MN has much more time to finish HO preparation, thus CDHO reduces dependence on mobility trace prediction algorithm.
Current HandOver (HO) mechanism usually cuts down the duration of service interruption by pre- executing some preparation operations before HO execution. But this technique is much dependant on mobility trace prediction algorithm, which is very difficult in actual environment. To resolve this problem, a novel HO mechanism based on Cooperative Diversity (CDHO) is proposed. CDHO introduces cooperative diversity between Mobile Node (MN) and source Base Station (BS) to extend the service duration in which source BS can satisfy MNs QoS requirement. In this extended duration, MN has much more time to finish HO preparation, thus CDHO reduces dependence on mobility trace prediction algorithm.
2011, 33(5): 1186-1192.
doi: 10.3724/SP.J.1146.2010.00962
Abstract:
The capacity issue of Physical-layer Network Coding (PNC) is investigated. According to the Max-Min Mutual Information (MMMI) criterion, a new opportunistic relaying scheme is proposed based on Amplify-and-Forward (AF). Then, the outage probability expressions are derived for the new proposed scheme as well as the schemes of ideal PNC and traditional direct transmission in frequency-nonselective Rayleigh fading channels. By the analysis, it is found that the system outage performance can be measured by one-way channel in some conditions, which are determined by the node transmission powers. Simulation results show that the outage performance is improved significantly when MMMI strategy is used.
The capacity issue of Physical-layer Network Coding (PNC) is investigated. According to the Max-Min Mutual Information (MMMI) criterion, a new opportunistic relaying scheme is proposed based on Amplify-and-Forward (AF). Then, the outage probability expressions are derived for the new proposed scheme as well as the schemes of ideal PNC and traditional direct transmission in frequency-nonselective Rayleigh fading channels. By the analysis, it is found that the system outage performance can be measured by one-way channel in some conditions, which are determined by the node transmission powers. Simulation results show that the outage performance is improved significantly when MMMI strategy is used.
2011, 33(5): 1193-1197.
doi: 10.3724/SP.J.1146.2010.00552
Abstract:
The two-dimensional virtual space smoothing algorithm is derived employing the received signals of all array elements and their conjugate data based on the rectangular array. By constructing virtual sub-array to eliminate the correlation between the interference signal and the desired signal, the array aperture loss is reduced and the spectral resolution of space is improved. A frequency-hopping communication system with inhibition of tracking interference is designed by combining this algorithm with phase compensation. The theoretical analysis and simulation results show that the new system is good on the tracking interference suppression with a -50 dB interference rejection for the tracking rejection and has a good bit error rate characteristics at -3 dB strong interference environment.
The two-dimensional virtual space smoothing algorithm is derived employing the received signals of all array elements and their conjugate data based on the rectangular array. By constructing virtual sub-array to eliminate the correlation between the interference signal and the desired signal, the array aperture loss is reduced and the spectral resolution of space is improved. A frequency-hopping communication system with inhibition of tracking interference is designed by combining this algorithm with phase compensation. The theoretical analysis and simulation results show that the new system is good on the tracking interference suppression with a -50 dB interference rejection for the tracking rejection and has a good bit error rate characteristics at -3 dB strong interference environment.
2011, 33(5): 1198-1203.
doi: 10.3724/SP.J.1146.2010.00713
Abstract:
Importing the concept of fuzzy set, this paper constructes membership function for measuring the complexity of chaotic pseudorandom sequences. On the basis of this, a new complexity metric is investigated to evaluate the unpredictability of the chaotic pseudorandom sequences based on the Fuzzy Entropy (FuzzyEn). Simulations and analysis results show that, the FuzzyEn works effectively to discern the changing complexities of the chaotic pseudorandom sequences, and compared with complexity metric based on the Approximate Entropy (ApEn) and symbolic dynamics approach, FuzzyEn has obvious advantages in the applicability of symbolic space, the sensitivity of vector dimension and the robustness of resolution parameter.
Importing the concept of fuzzy set, this paper constructes membership function for measuring the complexity of chaotic pseudorandom sequences. On the basis of this, a new complexity metric is investigated to evaluate the unpredictability of the chaotic pseudorandom sequences based on the Fuzzy Entropy (FuzzyEn). Simulations and analysis results show that, the FuzzyEn works effectively to discern the changing complexities of the chaotic pseudorandom sequences, and compared with complexity metric based on the Approximate Entropy (ApEn) and symbolic dynamics approach, FuzzyEn has obvious advantages in the applicability of symbolic space, the sensitivity of vector dimension and the robustness of resolution parameter.
2011, 33(5): 1204-1210.
doi: 10.3724/SP.J.1146.2010.01031
Abstract:
Generalized signcryption is a cryptographic primitive which could not only realize signcryption but also provide encryption and authentication alone. In this paper, the formal definition and a complete security notion of identity based generalized signcryption for multiple PKGs is defined. A concrete scheme is also proposed with security proof in standard model. Compared with several existing identity based signcryption schemes for multiple PKGs, the new scheme is more efficient and flexible.
Generalized signcryption is a cryptographic primitive which could not only realize signcryption but also provide encryption and authentication alone. In this paper, the formal definition and a complete security notion of identity based generalized signcryption for multiple PKGs is defined. A concrete scheme is also proposed with security proof in standard model. Compared with several existing identity based signcryption schemes for multiple PKGs, the new scheme is more efficient and flexible.
2011, 33(5): 1211-1216.
doi: 10.3724/SP.J.1146.2010.01050
Abstract:
The k-anonymity model is employed to protect the location privacy in Location-Based Services (LBS) in recent years. A Moving-Pattern Attack (MPA) is presented, in a scenario that the moving user keeps delivering queries. It is shown that traditional algorithms fail in this attack. In order to protect against MPA, a novel anonymity measurement based on entropy is proposed, which leads to a cloaking algorithm under mobile environments, i.e. Mclique. Experiments show that Mclique protects effectively user privacy against MPA. By simplifying the computing of entropy in Mclique, a fast cloaking algorithm, Fclique, is proposed. Experiments show that Fclique is capable of surviving MPA, and reduces greatly the time complexity as well.
The k-anonymity model is employed to protect the location privacy in Location-Based Services (LBS) in recent years. A Moving-Pattern Attack (MPA) is presented, in a scenario that the moving user keeps delivering queries. It is shown that traditional algorithms fail in this attack. In order to protect against MPA, a novel anonymity measurement based on entropy is proposed, which leads to a cloaking algorithm under mobile environments, i.e. Mclique. Experiments show that Mclique protects effectively user privacy against MPA. By simplifying the computing of entropy in Mclique, a fast cloaking algorithm, Fclique, is proposed. Experiments show that Fclique is capable of surviving MPA, and reduces greatly the time complexity as well.
2011, 33(5): 1217-1223.
doi: 10.3724/SP.J.1146.2010.01041
Abstract:
In network computing model, trust is the major driving force for interaction and collaboration among distributed entities. How to accurately quantify and evaluate trust is the research focus. A trust forecasting model is proposed based on entity context and time stamp. Trust grade space with 8 granularity is established. The multi-dimensional measurement standard is introduced to more scientific and accurate measure of interaction satisfaction degree. The direct trust calculation method with time self-decay is proposed, which overcomes the deficiency of existing models that do not adapt to dynamic changes environment. The recommendation trust is divided to direct and indirect recommendation trust. A similarity factor of entity scoring activities is introduced to caculate direct recommendation trust. The path self-decay factor is given to calculate indirect recommendation trust. A Distributed Storage Tree (DST) mechanism is proposed, which can improve stability and scalability of model. Simulation results show that compared to the exisitng trust model, the model can more effectively and accurately provide decision-making basis, and effectively inhibit malicious entities.
In network computing model, trust is the major driving force for interaction and collaboration among distributed entities. How to accurately quantify and evaluate trust is the research focus. A trust forecasting model is proposed based on entity context and time stamp. Trust grade space with 8 granularity is established. The multi-dimensional measurement standard is introduced to more scientific and accurate measure of interaction satisfaction degree. The direct trust calculation method with time self-decay is proposed, which overcomes the deficiency of existing models that do not adapt to dynamic changes environment. The recommendation trust is divided to direct and indirect recommendation trust. A similarity factor of entity scoring activities is introduced to caculate direct recommendation trust. The path self-decay factor is given to calculate indirect recommendation trust. A Distributed Storage Tree (DST) mechanism is proposed, which can improve stability and scalability of model. Simulation results show that compared to the exisitng trust model, the model can more effectively and accurately provide decision-making basis, and effectively inhibit malicious entities.
2011, 33(5): 1224-1228.
doi: 10.3724/SP.J.1146.2010.01058
Abstract:
The static nonlinear feature of narrow band Radio Frequency Power Amplifier (RF PA) is made as the fingerprint of wireless communication emitter. RF PA with unknown input can be looked as a static nonlinear Hammerstein model. The process of feature extraction from this model is split into two steps. The first step is signal samples whitening and the second is the estimation of Taylor series coefficients. The order statistics of the whitening signal samples is monotone. Then the features are estimated through linear regression using least square method. Comparing feature vectors of 4 RF power amplifiers results in that the proposed algorithm is effectively to identification different type of RF power amplifiers.
The static nonlinear feature of narrow band Radio Frequency Power Amplifier (RF PA) is made as the fingerprint of wireless communication emitter. RF PA with unknown input can be looked as a static nonlinear Hammerstein model. The process of feature extraction from this model is split into two steps. The first step is signal samples whitening and the second is the estimation of Taylor series coefficients. The order statistics of the whitening signal samples is monotone. Then the features are estimated through linear regression using least square method. Comparing feature vectors of 4 RF power amplifiers results in that the proposed algorithm is effectively to identification different type of RF power amplifiers.
2011, 33(5): 1229-1233.
doi: 10.3724/SP.J.1146.2010.01028
Abstract:
In view of high power consumption of current Digital Audio Broadcasting (DAB) radios AAC+ decoder implemented in DSP processor, this paper proposes an ASIC design of low-power AAC LC decoder. The design achieves the most basic decoding DAB+ program with very low hardware cost, and realizes skillfully the compatibility of two different standards DAB+ and DAB after adding to the DAB decoder chip. In order to achieve low power consumption, this design optimizes the inverse quantization and IMDCT algorithm and uses the time-sharing method. The system clock runs at 16.384 MHz, adopts 0.18 m CMOS technology, and power consumption is about 6.5 mW. Combined with the DAB channel decoder, it passes the real-time verification on the FPGA development board and completes the chip layout, and the chip area is 14 mm2.
In view of high power consumption of current Digital Audio Broadcasting (DAB) radios AAC+ decoder implemented in DSP processor, this paper proposes an ASIC design of low-power AAC LC decoder. The design achieves the most basic decoding DAB+ program with very low hardware cost, and realizes skillfully the compatibility of two different standards DAB+ and DAB after adding to the DAB decoder chip. In order to achieve low power consumption, this design optimizes the inverse quantization and IMDCT algorithm and uses the time-sharing method. The system clock runs at 16.384 MHz, adopts 0.18 m CMOS technology, and power consumption is about 6.5 mW. Combined with the DAB channel decoder, it passes the real-time verification on the FPGA development board and completes the chip layout, and the chip area is 14 mm2.
2011, 33(5): 1234-1237.
doi: 10.3724/SP.J.1146.2010.00977
Abstract:
This paper builds one speaker diarization and localization speech processing system based on Multiple Distance Microphone (MDM) for NIST evaluation, and proposes a modified clustering algorithm based on time delay estimation, which can decrease the complexity of speaker diarization and improve the correct rate under the guarantee of stable performance. A new time delay matrix structure is proposed, which can acquire multiple speakers direction angle. It is the real speech data collected under the standard session environment to validate the algorithms. The correct rate of proposed speaker diarization algorithm is similar with other speaker diarization system existed; Location algorithm direction angle error is less than 3. The results show that under appropriate conditions, the MDM system can be a better input device applied to multiple dialogue scenes.
This paper builds one speaker diarization and localization speech processing system based on Multiple Distance Microphone (MDM) for NIST evaluation, and proposes a modified clustering algorithm based on time delay estimation, which can decrease the complexity of speaker diarization and improve the correct rate under the guarantee of stable performance. A new time delay matrix structure is proposed, which can acquire multiple speakers direction angle. It is the real speech data collected under the standard session environment to validate the algorithms. The correct rate of proposed speaker diarization algorithm is similar with other speaker diarization system existed; Location algorithm direction angle error is less than 3. The results show that under appropriate conditions, the MDM system can be a better input device applied to multiple dialogue scenes.
2011, 33(5): 1238-1242.
doi: 10.3724/SP.J.1146.2010.01005
Abstract:
Spectrogram is a kind of graphic representation of time-frequency analysis of speech signals. Because spectrogram can be adopted to demonstrate the dynamic characteristics of time varying speech signals both in frequency domain and time domain, it has been widely employed in speech analysis and phonetic researches. This paper realizes a spectrogram on Field Programmable Gate Array (FPGA) with Short Time Fourier Transform (STFT) method by using a line structure butterfly process unit which adopted Radix4 decimation in time FFT algorithm. The spectrogram is also displayed on VGA displayer by adopting a non-linear mapping algorithm.
Spectrogram is a kind of graphic representation of time-frequency analysis of speech signals. Because spectrogram can be adopted to demonstrate the dynamic characteristics of time varying speech signals both in frequency domain and time domain, it has been widely employed in speech analysis and phonetic researches. This paper realizes a spectrogram on Field Programmable Gate Array (FPGA) with Short Time Fourier Transform (STFT) method by using a line structure butterfly process unit which adopted Radix4 decimation in time FFT algorithm. The spectrogram is also displayed on VGA displayer by adopting a non-linear mapping algorithm.
2011, 33(5): 1243-1247.
doi: 10.3724/SP.J.1146.2010.00871
Abstract:
By adaptively combining two separation systems with different step sizes, an adaptive combination algorithm is proposed for blind source separation. A smoothing parameter is used to adjust the proportion of the two systems in an attempt to put together the best properties of them. The adaptive updating rule for the smoothing parameter is obtained, and in view of the insufficiency of the proposed method, a concrete modified scheme is also presented. Experimental results demonstrate the good performance of the proposed approaches in stationary and non-stationary conditions.
By adaptively combining two separation systems with different step sizes, an adaptive combination algorithm is proposed for blind source separation. A smoothing parameter is used to adjust the proportion of the two systems in an attempt to put together the best properties of them. The adaptive updating rule for the smoothing parameter is obtained, and in view of the insufficiency of the proposed method, a concrete modified scheme is also presented. Experimental results demonstrate the good performance of the proposed approaches in stationary and non-stationary conditions.
2011, 33(5): 1248-1252.
doi: 10.3724/SP.J.1146.2010.00957
Abstract:
This paper designs and realizes a real-time image processor for SAR based on Field Programmable Gate Arrays (FPGA). The system is suitable for high resolution airborne spotlight mode SAR. The scheme applies the Polar Format Algorithm (PFA) first. Then the motion error phase is estimated and compensated in azimuth wavenumber domain. In this paper, the design approaches and the hardware system architecture are given and the resource usage, processing speed and image result are analyzed in detail. The real-time experiment results show that the system can process 1024 MB SAR raw data within 11 s, when the FPGA processing units work at 100 MHz. The good experimental image also proves the validity and reliability of the proposed system.
This paper designs and realizes a real-time image processor for SAR based on Field Programmable Gate Arrays (FPGA). The system is suitable for high resolution airborne spotlight mode SAR. The scheme applies the Polar Format Algorithm (PFA) first. Then the motion error phase is estimated and compensated in azimuth wavenumber domain. In this paper, the design approaches and the hardware system architecture are given and the resource usage, processing speed and image result are analyzed in detail. The real-time experiment results show that the system can process 1024 MB SAR raw data within 11 s, when the FPGA processing units work at 100 MHz. The good experimental image also proves the validity and reliability of the proposed system.
2011, 33(5): 1253-1256.
doi: 10.3724/SP.J.1146.2010.01043
Abstract:
In order to overcome the slow convergence rate and big mean square error of Constant Modulus Algorithm (CMA), an orthogonal wavelet transform constant modulus blind equalization algorithm based on the optimization of particle swarm is proposed, on the basis of analyzing the futures of orthogonal Wavelet Transform Constant Modulus blind equalization Algorithm (WT-CMA) and particle swarm algorithm. In the proposed algorithm, the equalizer weight vector can be optimized via making full use of effective global search of particle swarm algorithm and the de-correlation ability of wavelet transform. Computer simulations in underwater acoustic channels indicate that the proposed algorithm outperforms the CMA, the constant modulus blind equalization algorithm based on the Particle Swarm Optimization (PSO-CMA) and WT-CMA in improving the convergence rate and reducing inter symbol interference.
In order to overcome the slow convergence rate and big mean square error of Constant Modulus Algorithm (CMA), an orthogonal wavelet transform constant modulus blind equalization algorithm based on the optimization of particle swarm is proposed, on the basis of analyzing the futures of orthogonal Wavelet Transform Constant Modulus blind equalization Algorithm (WT-CMA) and particle swarm algorithm. In the proposed algorithm, the equalizer weight vector can be optimized via making full use of effective global search of particle swarm algorithm and the de-correlation ability of wavelet transform. Computer simulations in underwater acoustic channels indicate that the proposed algorithm outperforms the CMA, the constant modulus blind equalization algorithm based on the Particle Swarm Optimization (PSO-CMA) and WT-CMA in improving the convergence rate and reducing inter symbol interference.
2011, 33(5): 1257-1260.
doi: 10.3724/SP.J.1146.2010.00848
Abstract:
A recursive construction of Zero Correlation Zone (ZCZ) array pairs set is proposed. By using the orthogonal matrix, the interleaving and direct product techniques are applied to an array pairs set with the same energy. The obtained ZCZ array pair set not only has larger size but also preserves good correlation properties. The proposed technique can be generalized as a recursive construction of ZCZ punctured array pairs set.
A recursive construction of Zero Correlation Zone (ZCZ) array pairs set is proposed. By using the orthogonal matrix, the interleaving and direct product techniques are applied to an array pairs set with the same energy. The obtained ZCZ array pair set not only has larger size but also preserves good correlation properties. The proposed technique can be generalized as a recursive construction of ZCZ punctured array pairs set.
2011, 33(5): 1261-1265.
doi: 10.3724/SP.J.1146.2010.00797
Abstract:
In order to solve the issue that congestion often occurs in the process of data transmission, a Multi-path Optimizing routing protocol based on Predicting Congestion is proposed for wireless sensor network (which is named as MOPC protocol). This protocol is designed in the thinking of avoiding congestion initiatively. According with congestion predict degree, remaining energy and minimum hop count, path satisfaction degree model is build, which is used to realize the optimal path selection. It achieved local routing maintenance dynamically by setting change rate threshold of nodes forwarding satisfaction degree on the optimal path. Simulation results show that, MOPC routing protocol has good real-time performance and reliability, it could improve energy efficiency and extend network lifetime significantly.
In order to solve the issue that congestion often occurs in the process of data transmission, a Multi-path Optimizing routing protocol based on Predicting Congestion is proposed for wireless sensor network (which is named as MOPC protocol). This protocol is designed in the thinking of avoiding congestion initiatively. According with congestion predict degree, remaining energy and minimum hop count, path satisfaction degree model is build, which is used to realize the optimal path selection. It achieved local routing maintenance dynamically by setting change rate threshold of nodes forwarding satisfaction degree on the optimal path. Simulation results show that, MOPC routing protocol has good real-time performance and reliability, it could improve energy efficiency and extend network lifetime significantly.
2011, 33(5): 1266-1270.
doi: 10.3724/SP.J.1146.2010.01017
Abstract:
According to the broadcast encryption scheme with wide applications in the real world but its security and efficiency can not be taken into consideration in the model simultaneously, a novel identity-based broadcast encryption scheme is proposed by combining with Waters dual system encryption and the orthogonality property of composite-order bilinear groups. Based on the standard model without tags, the scheme can achieve constant-size key and ciphertext. The scheme is proved by using the three static assumptions which do not depend on the number of queries the attacker makes. Furthermore, the analysis results indicated that the scheme of this paper is fully secure and can satisfy the higher efficiency and practice requirement.
According to the broadcast encryption scheme with wide applications in the real world but its security and efficiency can not be taken into consideration in the model simultaneously, a novel identity-based broadcast encryption scheme is proposed by combining with Waters dual system encryption and the orthogonality property of composite-order bilinear groups. Based on the standard model without tags, the scheme can achieve constant-size key and ciphertext. The scheme is proved by using the three static assumptions which do not depend on the number of queries the attacker makes. Furthermore, the analysis results indicated that the scheme of this paper is fully secure and can satisfy the higher efficiency and practice requirement.
