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2010 Vol. 32, No. 9
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2010, 32(9): 2033-2038.
doi: 10.3724/SP.J.1146.2009.01149
Abstract:
Based on the large-scale path loss model for wireless communications, a Vehicular Ad hoc NETwork (VANET) in highway scenarios is modeled as a geometric random graph, the concept of effective networking area in VANET is proposed, the quasi-linear topological features of VANET is analyzed, the probability of nodes which have at least k neighbors located within its radio coverage is also derived, based on the assumption that the space headway under free flow conditions follows an approved traffic flow distribution. Experimental results demonstrate that the proposed algorithm, with the philosophy of thinking in probability, is an effective computational method on the node degree of a vehicular ad hoc network in highway scenarios.
Based on the large-scale path loss model for wireless communications, a Vehicular Ad hoc NETwork (VANET) in highway scenarios is modeled as a geometric random graph, the concept of effective networking area in VANET is proposed, the quasi-linear topological features of VANET is analyzed, the probability of nodes which have at least k neighbors located within its radio coverage is also derived, based on the assumption that the space headway under free flow conditions follows an approved traffic flow distribution. Experimental results demonstrate that the proposed algorithm, with the philosophy of thinking in probability, is an effective computational method on the node degree of a vehicular ad hoc network in highway scenarios.
2010, 32(9): 2039-2044.
doi: 10.3724/SP.J.1146.2009.01271
Abstract:
Wireless Multimedia Sensor Networks (WMSNs) can real-time monitor, collect and process multimedia information. They have wide applications. Compared to other traditional sensor networks, WMSNs need more bandwidth to transmit multimedia information. However, the limited radio frequency spectrum appears more and more precious as the wireless communication devices are gaining momentum. Dynamic spectrum allocation can extend the spectrum used by wireless multimedia sensor networks and eliminate the interferences. In this paper, a novel method for spectrum sensing and management is proposed. So that WMSNs which are limited by energy and computation ability can sense spectrum environment via periodical rotation and communicate by available spare spectrum. Finally, the validity of proposed methods are proved by the experiment.
Wireless Multimedia Sensor Networks (WMSNs) can real-time monitor, collect and process multimedia information. They have wide applications. Compared to other traditional sensor networks, WMSNs need more bandwidth to transmit multimedia information. However, the limited radio frequency spectrum appears more and more precious as the wireless communication devices are gaining momentum. Dynamic spectrum allocation can extend the spectrum used by wireless multimedia sensor networks and eliminate the interferences. In this paper, a novel method for spectrum sensing and management is proposed. So that WMSNs which are limited by energy and computation ability can sense spectrum environment via periodical rotation and communicate by available spare spectrum. Finally, the validity of proposed methods are proved by the experiment.
2010, 32(9): 2045-2051.
doi: 10.3724/SP.J.1146.2009.01234
Abstract:
This paper analyzes convergence and acceleration issues of distributed consensus time synchronization protocols in wireless sensor networks. By mapping synchronization iterations to Markov domain, the upper and lower bounds of protocol convergence rate are deduced in circulant networks, which proves that the protocol convergence rate is related to node neighbor size and network size. Matlab simulation results in co-uniform regular networks and co-uniform networks indicate the same conclusion. Moreover, it is found that in co-uniform non-regular networks, the protocol convergence rate will also be affected by neighbor size distribution. So an accelerating algorithm is proposed, which improves the convergence rate of distributed consensus time synchronization protocols by adjusting neighbor size distribution. Experiment results show that in a 100-node co-uniform network, the proposed accelerating algorithm can reduce the iteration counts of the distributed consensus time synchronization protocols by 25%, without any significant variation of the average node transmission radius.
This paper analyzes convergence and acceleration issues of distributed consensus time synchronization protocols in wireless sensor networks. By mapping synchronization iterations to Markov domain, the upper and lower bounds of protocol convergence rate are deduced in circulant networks, which proves that the protocol convergence rate is related to node neighbor size and network size. Matlab simulation results in co-uniform regular networks and co-uniform networks indicate the same conclusion. Moreover, it is found that in co-uniform non-regular networks, the protocol convergence rate will also be affected by neighbor size distribution. So an accelerating algorithm is proposed, which improves the convergence rate of distributed consensus time synchronization protocols by adjusting neighbor size distribution. Experiment results show that in a 100-node co-uniform network, the proposed accelerating algorithm can reduce the iteration counts of the distributed consensus time synchronization protocols by 25%, without any significant variation of the average node transmission radius.
2010, 32(9): 2052-2057.
doi: 10.3724/SP.J.1146.2009.01640
Abstract:
The research focus of this paper is to design a novel target tracking algorithm for binary sensor network (BSN). The weight in existing algorithms can not reflect the realtime relationship between target and sensing nodes. Distance weighted target tracking algorithm is proposed, in which the distance weight can reflect the realtime relationship between target and senisng nodes and thererfore has better performance than the existing algorithms. In distance weighted algorithm, sensing node should transmit both sensing information and distance information to the fusion center and consum more energy. Prediction-based distance weighted target tracking algorithm is provided, which can reduce energy consumption by the transmission of only sensing information. Simulation results show that prediction-based distance weighted algorithm can not only guarantee the tracking accuracy but also reduce energy consumption, compared with the existent algorithms.
The research focus of this paper is to design a novel target tracking algorithm for binary sensor network (BSN). The weight in existing algorithms can not reflect the realtime relationship between target and sensing nodes. Distance weighted target tracking algorithm is proposed, in which the distance weight can reflect the realtime relationship between target and senisng nodes and thererfore has better performance than the existing algorithms. In distance weighted algorithm, sensing node should transmit both sensing information and distance information to the fusion center and consum more energy. Prediction-based distance weighted target tracking algorithm is provided, which can reduce energy consumption by the transmission of only sensing information. Simulation results show that prediction-based distance weighted algorithm can not only guarantee the tracking accuracy but also reduce energy consumption, compared with the existent algorithms.
2010, 32(9): 2058-2064.
doi: 10.3724/SP.J.1146.2009.01228
Abstract:
As a congestion measure, queuing delay has many advantages. But packet loss can not be completely avoided if only queuing delay is used as a congestion measure. When the buffer is not large enough and some packets are dropped, queuing delay can not accurately reflect network congestion. In this paper, a congestion control model is proposed based on queuing delay and packet loss rate, in which dual-mode control is used. When the buffer is large enough, queuing delay is used as a congestion measure, the model achieves stable dynamic properties and weighted proportional fairness among heterogeneous flows. When the buffer is not large enough and packet loss is inevitable, packet loss rate is used as a congestion measure, and the model maintains almost the same performance as when there is no packet loss. The model is stable as it switches between the two modes and the transition is smooth.
As a congestion measure, queuing delay has many advantages. But packet loss can not be completely avoided if only queuing delay is used as a congestion measure. When the buffer is not large enough and some packets are dropped, queuing delay can not accurately reflect network congestion. In this paper, a congestion control model is proposed based on queuing delay and packet loss rate, in which dual-mode control is used. When the buffer is large enough, queuing delay is used as a congestion measure, the model achieves stable dynamic properties and weighted proportional fairness among heterogeneous flows. When the buffer is not large enough and packet loss is inevitable, packet loss rate is used as a congestion measure, and the model maintains almost the same performance as when there is no packet loss. The model is stable as it switches between the two modes and the transition is smooth.
2010, 32(9): 2065-2071.
doi: 10.3724/SP.J.1146.2009.01054
Abstract:
Reliable multicast in Ad hoc networks is challenging due to high error rate, low bandwidth, limited node power, and highly dynamic topology changes. In this paper, an efficient loss recovery scheme is proposed for reliable multicast (CoreRM). The basic idea is to apply the notion of cooperative communication to support local loss recovery. According different packet loss cases, CoreRM tries to retrieve the lost packet through progressively cooperating with neighboring nodes, upstream nodes or source node. In order to minimize recovery latency and retransmission overhead, CoreRM caches not only data packets but also the path which could be used for future possible packet recovery. In CoreRM, upstream nodes suppress duplicate NAKs to tackle feedback implosion. Both analytical and simulation results reveal that CoreRM significantly improves the multicast performance in terms of throughput and recovery latency compared with UDP and PGM.
Reliable multicast in Ad hoc networks is challenging due to high error rate, low bandwidth, limited node power, and highly dynamic topology changes. In this paper, an efficient loss recovery scheme is proposed for reliable multicast (CoreRM). The basic idea is to apply the notion of cooperative communication to support local loss recovery. According different packet loss cases, CoreRM tries to retrieve the lost packet through progressively cooperating with neighboring nodes, upstream nodes or source node. In order to minimize recovery latency and retransmission overhead, CoreRM caches not only data packets but also the path which could be used for future possible packet recovery. In CoreRM, upstream nodes suppress duplicate NAKs to tackle feedback implosion. Both analytical and simulation results reveal that CoreRM significantly improves the multicast performance in terms of throughput and recovery latency compared with UDP and PGM.
2010, 32(9): 2072-2076.
doi: 10.3724/SP.J.1146.2009.01440
Abstract:
In the LEO satellite spectrum sensing, choosing a proper frequency resolution for detecting the energy is very crucial. A too high resolution fails to detect spectrum holes which probably exist, while a too low one adds the computation and misjudges the jitter in frequency-domain as holes. Moreover, because backward-link sensing data need to be transferred to ground stations to do synthesis and detection, it is obvious that the smaller the quantity of data is, the easier for it to be transmitted. In order to improve the detecting accuracy and to reduce transmitting information, this paper proposes a LEO satellite spectrum sensing based on the multi-resolution signal decomposition. The simulation of this technology concludes that in backward sensing data transmission, multi-resolution signal decomposition can keep well shape of power spectral density function while largely decreasing spectrum sensing data. Besides, in the process of spectrum hole detecting, compared to fixed-resolution detecting, this technology can raise greatly the convergence rate of spectrum hole location and meantime reduce statistical error of holes.
In the LEO satellite spectrum sensing, choosing a proper frequency resolution for detecting the energy is very crucial. A too high resolution fails to detect spectrum holes which probably exist, while a too low one adds the computation and misjudges the jitter in frequency-domain as holes. Moreover, because backward-link sensing data need to be transferred to ground stations to do synthesis and detection, it is obvious that the smaller the quantity of data is, the easier for it to be transmitted. In order to improve the detecting accuracy and to reduce transmitting information, this paper proposes a LEO satellite spectrum sensing based on the multi-resolution signal decomposition. The simulation of this technology concludes that in backward sensing data transmission, multi-resolution signal decomposition can keep well shape of power spectral density function while largely decreasing spectrum sensing data. Besides, in the process of spectrum hole detecting, compared to fixed-resolution detecting, this technology can raise greatly the convergence rate of spectrum hole location and meantime reduce statistical error of holes.
2010, 32(9): 2077-2082.
doi: 10.3724/SP.J.1146.2010.00004
Abstract:
In order to improve the sum-rate of Two-way relay system, this paper proposes a Bi-directional Relay Selection (BRS) scheme in Two-way AF relay system. This scheme selects the optimal relay through joint considering the receive SNR (Signal Noise Rate) at the relay node and the channel gain between relay and destination node; Furthermore, this paper proposes two optimal power allocation scheme in Two-way relay system: (1) Optimal Power Allocation scheme based on Convex Optimization (OPA-CO), (2) Optimal Power Allocation scheme based on the Differences of Channel Gains (OPA-DCG); Scheme (1) establishes the optimal issue that how to maximize the sum-rate of Two-way relay system when total power is limited; Scheme (2) establishes a mathematical optimal model that how to maximize the increment of sum-rate based on the differences of channels gains. This paper uses an iterative power allocation algorithm to solve the optimal model mentioned above for the purpose of reducing the complexity of solving convex optimal mode. Simulation result shows that all the schemes mentioned above can improve the sum-rate.
In order to improve the sum-rate of Two-way relay system, this paper proposes a Bi-directional Relay Selection (BRS) scheme in Two-way AF relay system. This scheme selects the optimal relay through joint considering the receive SNR (Signal Noise Rate) at the relay node and the channel gain between relay and destination node; Furthermore, this paper proposes two optimal power allocation scheme in Two-way relay system: (1) Optimal Power Allocation scheme based on Convex Optimization (OPA-CO), (2) Optimal Power Allocation scheme based on the Differences of Channel Gains (OPA-DCG); Scheme (1) establishes the optimal issue that how to maximize the sum-rate of Two-way relay system when total power is limited; Scheme (2) establishes a mathematical optimal model that how to maximize the increment of sum-rate based on the differences of channels gains. This paper uses an iterative power allocation algorithm to solve the optimal model mentioned above for the purpose of reducing the complexity of solving convex optimal mode. Simulation result shows that all the schemes mentioned above can improve the sum-rate.
2010, 32(9): 2083-2088.
doi: 10.3724/SP.J.1146.2009.01158
Abstract:
A novel hybrid communications system, i.e., coherent Frequency-Hopping CDMA (FH/CDMA) system with Maximum Rate Combining (MRC) diversity reception and multicarrier scheme, is analyzed in Rayleigh fading channel. Due to the introduction of phase modulation, the phase precision in recovering carrier will affect on the system performance. The carrier recovery is implemented with the first-order Phase-Locked Loop (PLL) in the presence of AWGN in carrier recovery the loop, where the resulting steady-state phase error is appeared. The average Bit Error Rate (BER) of the ideal and the partial coherent FH/CDMA system are derived with means of Beaulieu series and characteristic function. Simulation results demonstrate that the BER performance of multi-user system is less susceptive to phase error and the dominating degradation is due to Multiple-Access Interference (MAI), compared to the single-user system. It is also shown that the effect of phase error and fading channel can be reduced by MRC reception more efficiently.
A novel hybrid communications system, i.e., coherent Frequency-Hopping CDMA (FH/CDMA) system with Maximum Rate Combining (MRC) diversity reception and multicarrier scheme, is analyzed in Rayleigh fading channel. Due to the introduction of phase modulation, the phase precision in recovering carrier will affect on the system performance. The carrier recovery is implemented with the first-order Phase-Locked Loop (PLL) in the presence of AWGN in carrier recovery the loop, where the resulting steady-state phase error is appeared. The average Bit Error Rate (BER) of the ideal and the partial coherent FH/CDMA system are derived with means of Beaulieu series and characteristic function. Simulation results demonstrate that the BER performance of multi-user system is less susceptive to phase error and the dominating degradation is due to Multiple-Access Interference (MAI), compared to the single-user system. It is also shown that the effect of phase error and fading channel can be reduced by MRC reception more efficiently.
2010, 32(9): 2089-2094.
doi: 10.3724/SP.J.1146.2009.01292
Abstract:
The analysis and research are based on the existing Farrow structure of Lagrange interpolation filter. The pipelining and parallel processing technology are used to improve the speed of filter. On this basis, a new structure based on the fast FIR algorithm is proposed. It is used to reduce the complexity of the parallel Farrow structure. The structure is implemented for FPGA. The analysis results show that the structure has faster operational rate and lower power consumption.
The analysis and research are based on the existing Farrow structure of Lagrange interpolation filter. The pipelining and parallel processing technology are used to improve the speed of filter. On this basis, a new structure based on the fast FIR algorithm is proposed. It is used to reduce the complexity of the parallel Farrow structure. The structure is implemented for FPGA. The analysis results show that the structure has faster operational rate and lower power consumption.
Dual-field Modular Multiplication Algorithm and Modular Inversion Algorithm with VLSI Implementation
2010, 32(9): 2095-2100.
doi: 10.3724/SP.J.1146.2009.01258
Abstract:
Modular multiplication and modular inversion algorithms are the kernel of elliptic curve cryptography. In this paper, a radix-4 dual-filed modular multiplication algorithm which is based on Blakelys algorithm is proposed. Booths algorithm is used to halve the iteration number of the Blakelys algorithm, and the sign estimation is employed to simplify the modular reduction operation. A dual-field modular inversion algorithm which is derived from extended Euclidean algorithm is presented to avoid magnitude comparison and shift efficiently. Furthermore, a unified hardware structure which can support dual-field modular multiplication and modular inversion operation is designed, and the result of the hardware implementation shows that the circuit can run 68% faster for modular multiplication and 17.4% faster for modular inversion without area increasing than others.
Modular multiplication and modular inversion algorithms are the kernel of elliptic curve cryptography. In this paper, a radix-4 dual-filed modular multiplication algorithm which is based on Blakelys algorithm is proposed. Booths algorithm is used to halve the iteration number of the Blakelys algorithm, and the sign estimation is employed to simplify the modular reduction operation. A dual-field modular inversion algorithm which is derived from extended Euclidean algorithm is presented to avoid magnitude comparison and shift efficiently. Furthermore, a unified hardware structure which can support dual-field modular multiplication and modular inversion operation is designed, and the result of the hardware implementation shows that the circuit can run 68% faster for modular multiplication and 17.4% faster for modular inversion without area increasing than others.
2010, 32(9): 2101-2105.
doi: 10.3724/SP.J.1146.2009.01325
Abstract:
Cyclic codes over the ringR=Fpm+uFpm can be seen as the ideals of R[x]/xpk-1. Based on the studing of ideals of R[x]/xpk-1, a unique method of representing cyclic codes of lengthpk and their mass formulas over the ringFpm+uFpm are provided. For the cyclic self-dual codes of lengthpk over the ring Fpm+uFpm, their structures and mass formulas are given.
Cyclic codes over the ringR=Fpm+uFpm can be seen as the ideals of R[x]/xpk-1. Based on the studing of ideals of R[x]/xpk-1, a unique method of representing cyclic codes of lengthpk and their mass formulas over the ringFpm+uFpm are provided. For the cyclic self-dual codes of lengthpk over the ring Fpm+uFpm, their structures and mass formulas are given.
2010, 32(9): 2106-2111.
doi: 10.3724/SP.J.1146.2009.01191
Abstract:
IEEE 802.16e-2005 standards PKMv2 protocol is an important secure guarantee for WiMAX (Worldwide Interoperability for Microwave Access) wireless network. In this paper, based on Protocol Composition Logic (PCL), the PKMv2 authentication protocols security is analyzed, the interleaving attack is found, and a new authentication protocol is proposed by using the Protocol Derivation System (PDS) in WiMAX wireless network based on the vulnerability of system security, finally a formal correctness and security proof of it is presented with Protocol Composition Logic (PCL). This new protocol is more secure than the PKMv2 security authentication protocol, and more suitable for complicated wireless network application environment used in WiMAX.
IEEE 802.16e-2005 standards PKMv2 protocol is an important secure guarantee for WiMAX (Worldwide Interoperability for Microwave Access) wireless network. In this paper, based on Protocol Composition Logic (PCL), the PKMv2 authentication protocols security is analyzed, the interleaving attack is found, and a new authentication protocol is proposed by using the Protocol Derivation System (PDS) in WiMAX wireless network based on the vulnerability of system security, finally a formal correctness and security proof of it is presented with Protocol Composition Logic (PCL). This new protocol is more secure than the PKMv2 security authentication protocol, and more suitable for complicated wireless network application environment used in WiMAX.
2010, 32(9): 2112-2118.
doi: 10.3724/SP.J.1146.2009.01197
Abstract:
The Cardinalized Probability Hypothesis Density (CPHD) fiter is a recursive Bayesian algorithm for estimating multiple target states with varying target number in clutter. Due to the fact that there is a missed detection problem in the CPHD filter, an improved algorithm is proposed, which provides a closed-form solution under Gaussian mixture assumptions. Firstly, the estimate to track association is made by labeling each Gaussian component, and then the weights of Gaussian components having been pruned and merged are reassigned twice. At first, the Gaussian components weights exceeding the detection threshold are reassigned, which can solve the missed detection issue effectively, and then the second distribution is made based on the fact that a target can only have one measurement, which improves the performance when the targets cross each other. Simulation results show that the improved CPHD filter has advantages over the ordinary one in both the aspects of multi-target state estimation and track maintenance.
The Cardinalized Probability Hypothesis Density (CPHD) fiter is a recursive Bayesian algorithm for estimating multiple target states with varying target number in clutter. Due to the fact that there is a missed detection problem in the CPHD filter, an improved algorithm is proposed, which provides a closed-form solution under Gaussian mixture assumptions. Firstly, the estimate to track association is made by labeling each Gaussian component, and then the weights of Gaussian components having been pruned and merged are reassigned twice. At first, the Gaussian components weights exceeding the detection threshold are reassigned, which can solve the missed detection issue effectively, and then the second distribution is made based on the fact that a target can only have one measurement, which improves the performance when the targets cross each other. Simulation results show that the improved CPHD filter has advantages over the ordinary one in both the aspects of multi-target state estimation and track maintenance.
2010, 32(9): 2119-2125.
doi: 10.3724/SP.J.1146.2009.01245
Abstract:
Small scale target tracking is one of the primary difficulties in visual tracking. Two major problems in mean shift small target tracking algorithm are presented in this paper, namely tracking interrupt and target losing. To tackle these problems, the Parzen windows density estimation method is modified to interpolate the histogram of the target candidate. The Kullback-Leibler distance is employed as a new similarity measure function of the target model and the target candidate. And its corresponding weight computation and new location expressions are derived. On the basis of these works, a new mean shift algorithm is proposed for small target tracking. Several tracking experiments for real world video sequences show that the proposed algorithm can track the target successively and accurately. It can successfully track very small targets with only 612 pixels.
Small scale target tracking is one of the primary difficulties in visual tracking. Two major problems in mean shift small target tracking algorithm are presented in this paper, namely tracking interrupt and target losing. To tackle these problems, the Parzen windows density estimation method is modified to interpolate the histogram of the target candidate. The Kullback-Leibler distance is employed as a new similarity measure function of the target model and the target candidate. And its corresponding weight computation and new location expressions are derived. On the basis of these works, a new mean shift algorithm is proposed for small target tracking. Several tracking experiments for real world video sequences show that the proposed algorithm can track the target successively and accurately. It can successfully track very small targets with only 612 pixels.
2010, 32(9): 2126-2132.
doi: 10.3724/SP.J.1146.2009.01129
Abstract:
Geometric active contour is used as a powerful tool to address image segmentation problems. Recently, a new region-based active contour model based on pairwise similarity between pixels, i.e., Graph Portioning Active Contours (GPAC) is presented, and well adapted to segment images with intensity homogeneity. However, it only takes spectral similarity as the cost function between vertices, and can not obtain satisfactory segmentation results for low contrast images with weak boundaries. In order to overcoming this limitation of GPAC model, a novel localized graph-cuts based multiphase active contours model using geodesic kernel based cost function is proposed. Experimental results of natural images verify that the model is efficient and accurate.
Geometric active contour is used as a powerful tool to address image segmentation problems. Recently, a new region-based active contour model based on pairwise similarity between pixels, i.e., Graph Portioning Active Contours (GPAC) is presented, and well adapted to segment images with intensity homogeneity. However, it only takes spectral similarity as the cost function between vertices, and can not obtain satisfactory segmentation results for low contrast images with weak boundaries. In order to overcoming this limitation of GPAC model, a novel localized graph-cuts based multiphase active contours model using geodesic kernel based cost function is proposed. Experimental results of natural images verify that the model is efficient and accurate.
Accelerate the Filtering Process of Filtered Back Projection Algorithm Using Fast Hadamard Transform
2010, 32(9): 2133-2138.
doi: 10.3724/SP.J.1146.2009.01635
Abstract:
To speedup the filtering process of the Filtered Back Projection (FBP) algorithm, a fast linear convolution algorithm using Fast Hadamard Transform (FHT) is proposed. The characteristic of Hadamard transform and its time complexity is analyzed. The matrix expression of using FHT to calculate linear convolution is designed. The equation of the Hadamard filter gain matrix is deduced. The acceleration principle and applicable condition of the method are analyzed. Theoretical analysis demonstrates that the method is faster than the FFT-convolution method for one time. The simulation experiment demonstrates that the method can advanced the filtering speed for about one time compared to the FFT-convolution method in the condition of no impacting the reconstructed images precision.
To speedup the filtering process of the Filtered Back Projection (FBP) algorithm, a fast linear convolution algorithm using Fast Hadamard Transform (FHT) is proposed. The characteristic of Hadamard transform and its time complexity is analyzed. The matrix expression of using FHT to calculate linear convolution is designed. The equation of the Hadamard filter gain matrix is deduced. The acceleration principle and applicable condition of the method are analyzed. Theoretical analysis demonstrates that the method is faster than the FFT-convolution method for one time. The simulation experiment demonstrates that the method can advanced the filtering speed for about one time compared to the FFT-convolution method in the condition of no impacting the reconstructed images precision.
2010, 32(9): 2139-2144.
doi: 10.3724/SP.J.1146.2009.01323
Abstract:
This paper describes a novel optimization framework for visual codebook generation. Firstly, the Condition Number (CN) is applied to evaluate the stability of initial visual features, and the well conditioned features are preserved by eliminating the bad ones. At the mean time, an adaptive algorithm to generate low-dimensional visual words is proposed by studying the relationship between clustering and dimension-reducing. In order to overcome the popular LBG codebook design algorithm suffers from local optimality and is sensitive to the initial solution, a parameter called neighborhood-support for each feature is calculated according to clustering structure, which is used to select initial visual words adaptively. Finally, the rational distortion function is redefined using Silhouette. Compared with traditional algorithm, the presented algorithm has excellent properties at simultaneous clustering and dimension reduction, good robustness and adaptive optimization. A good performance (73.46% classification rate) of application this method to 13-Scene classification is obtained by using Probabilistic Latent Semantic Analysis (PLSA).
This paper describes a novel optimization framework for visual codebook generation. Firstly, the Condition Number (CN) is applied to evaluate the stability of initial visual features, and the well conditioned features are preserved by eliminating the bad ones. At the mean time, an adaptive algorithm to generate low-dimensional visual words is proposed by studying the relationship between clustering and dimension-reducing. In order to overcome the popular LBG codebook design algorithm suffers from local optimality and is sensitive to the initial solution, a parameter called neighborhood-support for each feature is calculated according to clustering structure, which is used to select initial visual words adaptively. Finally, the rational distortion function is redefined using Silhouette. Compared with traditional algorithm, the presented algorithm has excellent properties at simultaneous clustering and dimension reduction, good robustness and adaptive optimization. A good performance (73.46% classification rate) of application this method to 13-Scene classification is obtained by using Probabilistic Latent Semantic Analysis (PLSA).
2010, 32(9): 2145-2150.
doi: 10.3724/SP.J.1146.2009.01505
Abstract:
To implement fault detection under large-scale, strong dynamic, high reliability required network environments, the traditional fault message dissemination would encounter network congestion, latency instability etc.. A fault detection protocol based on self-organized neighborhood construction is proposed, and agent nodes are chosen to implement detection between neighborhoods. In every single zone, a random dissemination fault detection algorithm called Self-Organized Neighborhood Fault Detection Protocol (SONFDP) is designed. This protocol can avoid network congestion caused by flood, reduce the network overhead and extend the scalability of fault detection. Meanwhile, a mechanism of redundant message avoidance is designed to further reduce the number of messages generated by detection. SONFDP is proven to be correct and effective by relevant mathematical analysis and experiments.
To implement fault detection under large-scale, strong dynamic, high reliability required network environments, the traditional fault message dissemination would encounter network congestion, latency instability etc.. A fault detection protocol based on self-organized neighborhood construction is proposed, and agent nodes are chosen to implement detection between neighborhoods. In every single zone, a random dissemination fault detection algorithm called Self-Organized Neighborhood Fault Detection Protocol (SONFDP) is designed. This protocol can avoid network congestion caused by flood, reduce the network overhead and extend the scalability of fault detection. Meanwhile, a mechanism of redundant message avoidance is designed to further reduce the number of messages generated by detection. SONFDP is proven to be correct and effective by relevant mathematical analysis and experiments.
2010, 32(9): 2151-2155.
doi: 10.3724/SP.J.1146.2009.01346
Abstract:
In order to improve recovery accuracy for compressed sensing, a Stagewise Weak selection Modifying approximation Conjugate Gradient Pursuit (StWMCGP) algorithm is proposed in this paper. This algorithm modifies the direction in the directional pursuit algorithm and clearly presents a stopping criterion to search the indices of elements and get a set. Then the evaluation of sparse signal is obtained by using Least-squares algorithm and the set. Simulated results show that for the same sparsity level, the number of measurements needed by the algorithm is about 20% less than that needed by MP or StOMP-FDR to exactly recover. When recovering two-dimensional image signal, the recovery accuracy of this algorithm is about 1% higher than that of BCS or StOMP-FAR.
In order to improve recovery accuracy for compressed sensing, a Stagewise Weak selection Modifying approximation Conjugate Gradient Pursuit (StWMCGP) algorithm is proposed in this paper. This algorithm modifies the direction in the directional pursuit algorithm and clearly presents a stopping criterion to search the indices of elements and get a set. Then the evaluation of sparse signal is obtained by using Least-squares algorithm and the set. Simulated results show that for the same sparsity level, the number of measurements needed by the algorithm is about 20% less than that needed by MP or StOMP-FDR to exactly recover. When recovering two-dimensional image signal, the recovery accuracy of this algorithm is about 1% higher than that of BCS or StOMP-FAR.
2010, 32(9): 2156-2160.
doi: 10.3724/SP.J.1146.2009.01364
Abstract:
The precise passive locating and tracking technology for a single observer demands high accuracy estimation of Doppler frequency rate produced by the radial acceleration between the target and the observer from the received signals. The frequency rate cannot denote the Doppler frequency rate for the PSK signal. A phase compensation based algorithm for Doppler frequency rate estimation from BPSK coherent pulse train is presented to conquer the problem. Both the fixed and alterable pulse repetition frequency (PRF) cases are considered. The limitation between the Doppler frequency rate and the sampling frequency, the observing time and the PRF is given. The simulation results show that the proposed algorithm achieves a 4~6 dB lower SNR threshold than the known ones in the typical condition.
The precise passive locating and tracking technology for a single observer demands high accuracy estimation of Doppler frequency rate produced by the radial acceleration between the target and the observer from the received signals. The frequency rate cannot denote the Doppler frequency rate for the PSK signal. A phase compensation based algorithm for Doppler frequency rate estimation from BPSK coherent pulse train is presented to conquer the problem. Both the fixed and alterable pulse repetition frequency (PRF) cases are considered. The limitation between the Doppler frequency rate and the sampling frequency, the observing time and the PRF is given. The simulation results show that the proposed algorithm achieves a 4~6 dB lower SNR threshold than the known ones in the typical condition.
2010, 32(9): 2161-2166.
doi: 10.3724/SP.J.1146.2009.01204
Abstract:
Due to the density model selection problem of amplitudes in each range cells for radar target recognition using High-Resolution Range Profile (HRRP), a radar target recognition approach based on the semiparametric density estimation is proposed in this paper. Starting with the parametric density estimation, semiparametric method has the ability to make use of empirical knowledge which is known as the approximate Gamma distribution of amplitudes in each HRRP range cells, and the Gamma density estimate is then corrected by multiplying with a nonparametric estimation of a correction factor. Obviously, both advantages of parametric method and nonparametric method are merged in the semiparametric density estimation. Simulation results based on the HRRP dataset of five aircraft models demonstrate the effectiveness of the proposed approach.
Due to the density model selection problem of amplitudes in each range cells for radar target recognition using High-Resolution Range Profile (HRRP), a radar target recognition approach based on the semiparametric density estimation is proposed in this paper. Starting with the parametric density estimation, semiparametric method has the ability to make use of empirical knowledge which is known as the approximate Gamma distribution of amplitudes in each HRRP range cells, and the Gamma density estimate is then corrected by multiplying with a nonparametric estimation of a correction factor. Obviously, both advantages of parametric method and nonparametric method are merged in the semiparametric density estimation. Simulation results based on the HRRP dataset of five aircraft models demonstrate the effectiveness of the proposed approach.
2010, 32(9): 2167-2171.
doi: 10.3724/SP.J.1146.2009.01329
Abstract:
This paper presents a novel method for target localization and Doppler frequency estimation in bistatic MIMO radar. By utilizing the biorthogonality of matrices, a reasonable cost function is constructed. Via iteratively solving the cost function and a systematical multistage decomposition process, the two-dimensional angles and Doppler frequency of each target are estimated in turn. Simulation results demonstrate that compared with the ESPRIT based methods, this new method has the Doppler estimation capability, can eliminate the effect of the transmitted waveforms on target localization and is applicable to sensor arrays without an invariance structure.
This paper presents a novel method for target localization and Doppler frequency estimation in bistatic MIMO radar. By utilizing the biorthogonality of matrices, a reasonable cost function is constructed. Via iteratively solving the cost function and a systematical multistage decomposition process, the two-dimensional angles and Doppler frequency of each target are estimated in turn. Simulation results demonstrate that compared with the ESPRIT based methods, this new method has the Doppler estimation capability, can eliminate the effect of the transmitted waveforms on target localization and is applicable to sensor arrays without an invariance structure.
2010, 32(9): 2172-2178.
doi: 10.3724/SP.J.1146.2009.01102
Abstract:
In this paper, an approach, based on sub-band synthesis and general facet model, is proposed for Ultra- WideBand (UWB) radar ground clutter modeling, simulation and analysis of clutter statistics in the case of different incident angle and relative bandwidth is respectively proposed. Firstly, the facet is divided into a series of small segments (called general facet) according to ground shape; UWB radar work bandwidth is splited into a bank of sub-bands (narrow-bands). The second step is to obtain the individual facet clutter backscattering coefficient (0) from the sub-bands. Finally, the method of sub-band synthesis is utilized to get UWB radar ground clutter model. According to clutter simulation, it is found that the UWB radar ground clutter Probability Density Function (PDF) curve varies with the fluctuation of incident angle or relative bandwidth. However, UWB radar PDF curve is characteristic of low barycenter and fat tail, furthermore, the tail become more heavy when the relative bandwidth of UWB radar increase. Simulation results show that the method of frequency splitting and sub-bands synthesis is feasible.
In this paper, an approach, based on sub-band synthesis and general facet model, is proposed for Ultra- WideBand (UWB) radar ground clutter modeling, simulation and analysis of clutter statistics in the case of different incident angle and relative bandwidth is respectively proposed. Firstly, the facet is divided into a series of small segments (called general facet) according to ground shape; UWB radar work bandwidth is splited into a bank of sub-bands (narrow-bands). The second step is to obtain the individual facet clutter backscattering coefficient (0) from the sub-bands. Finally, the method of sub-band synthesis is utilized to get UWB radar ground clutter model. According to clutter simulation, it is found that the UWB radar ground clutter Probability Density Function (PDF) curve varies with the fluctuation of incident angle or relative bandwidth. However, UWB radar PDF curve is characteristic of low barycenter and fat tail, furthermore, the tail become more heavy when the relative bandwidth of UWB radar increase. Simulation results show that the method of frequency splitting and sub-bands synthesis is feasible.
2010, 32(9): 2179-2183.
doi: 10.3724/SP.J.1146.2009.01459
Abstract:
An algorithm combined MUSIC with ESPRIT for angle estimation based on two- or four-order statistics in bistatic MIMO radar system is presented in this paper. The proposed method based on two-order expectation is under the spatial Gaussian white noise environment and four-order cumulant the colored noise. By exploiting MUSIC with one-sensor owing to its extended array aperture and ESPRIT with two-sensor via the rotational invariance property of signal-subspace at the receive end, the Direction Of Departures (DODs) and Direction Of Arrivals (DOAs) of the targets can be estimated separately and paired automatically. The computational burden can be reduced since two-dimensional parameter estimation has been separated into two one-dimensional forms. Numerical results are presented to demonstrate the effectiveness of the method advanced.
An algorithm combined MUSIC with ESPRIT for angle estimation based on two- or four-order statistics in bistatic MIMO radar system is presented in this paper. The proposed method based on two-order expectation is under the spatial Gaussian white noise environment and four-order cumulant the colored noise. By exploiting MUSIC with one-sensor owing to its extended array aperture and ESPRIT with two-sensor via the rotational invariance property of signal-subspace at the receive end, the Direction Of Departures (DODs) and Direction Of Arrivals (DOAs) of the targets can be estimated separately and paired automatically. The computational burden can be reduced since two-dimensional parameter estimation has been separated into two one-dimensional forms. Numerical results are presented to demonstrate the effectiveness of the method advanced.
2010, 32(9): 2184-2190.
doi: 10.3724/SP.J.1146.2009.01274
Abstract:
To eliminate the azimuthal spectral folding of spotlight Synthetic Aperture Radar (SAR) and the serious coupling between range and azimuth in high squint mode, an algorithm based on azimuth deramp and Nonlinear Frequency Scaling (NFS) is proposed. First, azimuth deramp operation eliminates the azimuthal spectral folding. Then nonlinear frequency scaling compensating the azimuth phase with the range scale variation is adopted to fulfill the focusing of the swath. Simulation results illustrate that it can eliminate azimuthal spectral folding, possess high precision and satisfy the imaging quality of high squint spotlight SAR and large scene swath.
To eliminate the azimuthal spectral folding of spotlight Synthetic Aperture Radar (SAR) and the serious coupling between range and azimuth in high squint mode, an algorithm based on azimuth deramp and Nonlinear Frequency Scaling (NFS) is proposed. First, azimuth deramp operation eliminates the azimuthal spectral folding. Then nonlinear frequency scaling compensating the azimuth phase with the range scale variation is adopted to fulfill the focusing of the swath. Simulation results illustrate that it can eliminate azimuthal spectral folding, possess high precision and satisfy the imaging quality of high squint spotlight SAR and large scene swath.
2010, 32(9): 2191-2196.
doi: 10.3724/SP.J.1146.2009.01233
Abstract:
The Forward Scattering Radar (FSR) can obtain moving target profile image with the technology of Shadow Inverse Synthetic Aperture Radar (SISAR), which can be used as target classification and identification. In order to research the effect of multi-polarization on moving target identification in FSR, the following work is carried out. Firstly, based on the theory of SISAR, the connection between forward scattering Radar Cross Section (RCS) and spectral information of profile image is established. Secondly, multi-polarization is firstly introduced to FSR target identification, and the target forward scattering RCS under multi-polarization conditions is obtained using the software of CST. Finally, by analyzing the simulation results, it is found that the same target has a different forward scattering RCS side-lobe under different polarization conditions. This difference corresponds to the difference of target profile image. The more information of target profile can be obtained using joint multi-polarization. The simulation results verify that multi-polarization can improve the ability of target classification and identification in FSR.
The Forward Scattering Radar (FSR) can obtain moving target profile image with the technology of Shadow Inverse Synthetic Aperture Radar (SISAR), which can be used as target classification and identification. In order to research the effect of multi-polarization on moving target identification in FSR, the following work is carried out. Firstly, based on the theory of SISAR, the connection between forward scattering Radar Cross Section (RCS) and spectral information of profile image is established. Secondly, multi-polarization is firstly introduced to FSR target identification, and the target forward scattering RCS under multi-polarization conditions is obtained using the software of CST. Finally, by analyzing the simulation results, it is found that the same target has a different forward scattering RCS side-lobe under different polarization conditions. This difference corresponds to the difference of target profile image. The more information of target profile can be obtained using joint multi-polarization. The simulation results verify that multi-polarization can improve the ability of target classification and identification in FSR.
2010, 32(9): 2197-2200.
doi: 10.3724/SP.J.1146.2010.00151
Abstract:
A method for multi-target localization based on polynomial rooting is developed in bistatic MIMO radar. Utilizing the property of transmit-receive steering vector, the two-dimensional (2-D) direction finding is transformed into two 1-D direction finding procedures. Then the polynomial rooting technique is employed to determine the 1-D direction. The proposed method avoids the conventional 2-D spectrum peak searching, and the estimated parameters are automatically paired without additional paring computation. Moreover the maximum number of targets resolved by this method is no smaller than the number of array elements. Numerical results verify the effectiveness of this method.
A method for multi-target localization based on polynomial rooting is developed in bistatic MIMO radar. Utilizing the property of transmit-receive steering vector, the two-dimensional (2-D) direction finding is transformed into two 1-D direction finding procedures. Then the polynomial rooting technique is employed to determine the 1-D direction. The proposed method avoids the conventional 2-D spectrum peak searching, and the estimated parameters are automatically paired without additional paring computation. Moreover the maximum number of targets resolved by this method is no smaller than the number of array elements. Numerical results verify the effectiveness of this method.
2010, 32(9): 2201-2207.
doi: 10.3724/SP.J.1146.2009.01218
Abstract:
According to the performance loss of moving target detection for a multi-channel SAR/GMTI system caused by the heterogeneous clutter environments, this paper proposes a new improved FRACTA algorithm. It arises from the improvements of the FARCTA algorithm and is proved to be more effective and computationally efficient for a multi-channel SAR system. As is verified by experimental results, this algorithm greatly overperforms the traditional detection method and shows robust in heterogeneous environments.
According to the performance loss of moving target detection for a multi-channel SAR/GMTI system caused by the heterogeneous clutter environments, this paper proposes a new improved FRACTA algorithm. It arises from the improvements of the FARCTA algorithm and is proved to be more effective and computationally efficient for a multi-channel SAR system. As is verified by experimental results, this algorithm greatly overperforms the traditional detection method and shows robust in heterogeneous environments.
2010, 32(9): 2208-2214.
doi: 10.3724/SP.J.1146.2009.01162
Abstract:
In order to improve the speed of interferometric processing for the airborne dual-antenna interferometric Synthetic Aperture Radar (SAR) system and also remain the accuracy of the registration, the non-linear approximation in the range Extended Chirp Scaling (ECS) auto-registration imaging algorithm is presented in the paper. This algorithm realizes the accurate auto-registration in the range in course of the imaging processing by the non-linear approximation to the path difference caused by the different visual angles of the two antennas. It increases the speed of generating the interferometric phase largely and preserves the higher accuracy of the registration meanwhile. Through the processing of the simulation data and the real interferometric data and the analysis of the impact of the systemic parameters on the accuracy of registration, the validity of the algorithm presented in the paper is proved.
In order to improve the speed of interferometric processing for the airborne dual-antenna interferometric Synthetic Aperture Radar (SAR) system and also remain the accuracy of the registration, the non-linear approximation in the range Extended Chirp Scaling (ECS) auto-registration imaging algorithm is presented in the paper. This algorithm realizes the accurate auto-registration in the range in course of the imaging processing by the non-linear approximation to the path difference caused by the different visual angles of the two antennas. It increases the speed of generating the interferometric phase largely and preserves the higher accuracy of the registration meanwhile. Through the processing of the simulation data and the real interferometric data and the analysis of the impact of the systemic parameters on the accuracy of registration, the validity of the algorithm presented in the paper is proved.
2010, 32(9): 2215-2219.
doi: 10.3724/SP.J.1146.2009.01426
Abstract:
Water shows low gray level and small wave from remote sensing images. As the fastest segmentation algorithm, 1D Otsu is used for Synthetic Aperture Radar (SAR) image segmentation. Level relation between multilevel Otsu and recursive Otsu is proved, and the evaluation of segmentation results is proposed, then quantitative comparison is given using SAR image. Results show that multilevel Otsu has better outline of water region, and can be used for SAR auto bridge recognition and scene matching.
Water shows low gray level and small wave from remote sensing images. As the fastest segmentation algorithm, 1D Otsu is used for Synthetic Aperture Radar (SAR) image segmentation. Level relation between multilevel Otsu and recursive Otsu is proved, and the evaluation of segmentation results is proposed, then quantitative comparison is given using SAR image. Results show that multilevel Otsu has better outline of water region, and can be used for SAR auto bridge recognition and scene matching.
2010, 32(9): 2220-2225.
doi: 10.3724/SP.J.1146.2009.01278
Abstract:
The improved Ambiguity Function Method (AFM) method of intersection point on sphere is an effective algorithm for attitude determination using GPS signal, but the success rate is influenced by observation noise significantly. To deal this problem, in this paper, the error analysis is given and a further improvement method is proposed. First the original algorithm is extended under the double difference observation model. Then the statistical properties of noise and error propagation characteristics are both analyzed, which are followed by in-depth study of its affects to the success rate of attitude determination. Finally the noise sensitivity of the solution process is reduced by integer ambiguity recognition algorithm. The testing results show that the success rate of GPS attitude determination of the proposed algorithm increases greatly over that of the original algorithm while the restriction on public clocks is eliminated.
The improved Ambiguity Function Method (AFM) method of intersection point on sphere is an effective algorithm for attitude determination using GPS signal, but the success rate is influenced by observation noise significantly. To deal this problem, in this paper, the error analysis is given and a further improvement method is proposed. First the original algorithm is extended under the double difference observation model. Then the statistical properties of noise and error propagation characteristics are both analyzed, which are followed by in-depth study of its affects to the success rate of attitude determination. Finally the noise sensitivity of the solution process is reduced by integer ambiguity recognition algorithm. The testing results show that the success rate of GPS attitude determination of the proposed algorithm increases greatly over that of the original algorithm while the restriction on public clocks is eliminated.
2010, 32(9): 2226-2230.
doi: 10.3724/SP.J.1146.2009.01212
Abstract:
An H-shaped conformal microstrip antenna array mounted on an irregular curved surface is optimized and designed in this paper and the radiation pattern of this conformal array is synthesized using the Self-adaptive Hybrid Genetic Algorithms (SHGA). The optimized azimuth radiation pattern of the conformal array is almost omnidirectional and the elevation radiation pattern is concentrated in the horizontal direction. Finally, the optimized results are analyzed in view of the phasic error. The results show that the proposed procedure is an effective and feasible method for designing the conformal antenna array on an irregular curved surface.
An H-shaped conformal microstrip antenna array mounted on an irregular curved surface is optimized and designed in this paper and the radiation pattern of this conformal array is synthesized using the Self-adaptive Hybrid Genetic Algorithms (SHGA). The optimized azimuth radiation pattern of the conformal array is almost omnidirectional and the elevation radiation pattern is concentrated in the horizontal direction. Finally, the optimized results are analyzed in view of the phasic error. The results show that the proposed procedure is an effective and feasible method for designing the conformal antenna array on an irregular curved surface.
2010, 32(9): 2231-2235.
doi: 10.3724/SP.J.1146.2009.01249
Abstract:
Power control techniques for wireless sensor networks are significant for network connectivity, energy efficiency, network capacity, throughput, real time performance and etc. It is one of the supporting technologies for the deployment of wireless sensor networks. This paper proposes an Adaptive Power Control Strategy (APCS) fitted for wireless sensor networks. It is a distributed algorithm based on local information which can obtain an excellent target topology by adjusting the path loss exponent and the power control parameter. It still can satisfy applications of a higher real-time performance and fault tolerance capacity. In addition, the proposed algorithm adopts a dynamic power control strategy to maintain the network connectivity which prolongs the network life time. Simulation results show the effectiveness of the proposed method.
Power control techniques for wireless sensor networks are significant for network connectivity, energy efficiency, network capacity, throughput, real time performance and etc. It is one of the supporting technologies for the deployment of wireless sensor networks. This paper proposes an Adaptive Power Control Strategy (APCS) fitted for wireless sensor networks. It is a distributed algorithm based on local information which can obtain an excellent target topology by adjusting the path loss exponent and the power control parameter. It still can satisfy applications of a higher real-time performance and fault tolerance capacity. In addition, the proposed algorithm adopts a dynamic power control strategy to maintain the network connectivity which prolongs the network life time. Simulation results show the effectiveness of the proposed method.
2010, 32(9): 2236-2240.
doi: 10.3724/SP.J.1146.2009.01326
Abstract:
For the limited processing, storage and energy of network nodes in the wireless sensor network environment, a distributed JPEG2000 coding algorithm based on mobile agent is proposed. Multiple network nodes are utilized to the image distributed coding and mobile Agent mechanism is used to communicate among network nodes. The energy consumption of single node is reduced under the invariant coding performance of the image, thus prevents the system from paralysis caused by the energy depletion of single node and prolongs the life cycle of the system. Simulation results show that the proposed algorithm is better communication capability of network nodes while the quality of the image is invariant after the coding, and can achieve a good balance of the network energy consumption and prolong the network life cycle 3 times as before.
For the limited processing, storage and energy of network nodes in the wireless sensor network environment, a distributed JPEG2000 coding algorithm based on mobile agent is proposed. Multiple network nodes are utilized to the image distributed coding and mobile Agent mechanism is used to communicate among network nodes. The energy consumption of single node is reduced under the invariant coding performance of the image, thus prevents the system from paralysis caused by the energy depletion of single node and prolongs the life cycle of the system. Simulation results show that the proposed algorithm is better communication capability of network nodes while the quality of the image is invariant after the coding, and can achieve a good balance of the network energy consumption and prolong the network life cycle 3 times as before.
2010, 32(9): 2241-2244.
doi: 10.3724/SP.J.1146.2009.01265
Abstract:
Because of the characteristics of Ad hoc networks, the theory of strand spaces can not analyzes the security of routing protocol. In this paper, the theory of strand spaces is first extended and the credibility of intermediate node is added. Subsequently, this extended theory is applied to analyzing the security of ARAN routing protocol and a new formal analysis method is proposed for Ad hoc networks routing protocol. The results show that it has replay attacks and conspiracy attacks in ARAN routing protocol. The method is proved to be valid.
Because of the characteristics of Ad hoc networks, the theory of strand spaces can not analyzes the security of routing protocol. In this paper, the theory of strand spaces is first extended and the credibility of intermediate node is added. Subsequently, this extended theory is applied to analyzing the security of ARAN routing protocol and a new formal analysis method is proposed for Ad hoc networks routing protocol. The results show that it has replay attacks and conspiracy attacks in ARAN routing protocol. The method is proved to be valid.
2010, 32(9): 2245-2248.
doi: 10.3724/SP.J.1146.2010.00225
Abstract:
With development of computer technology, especially Internet technology, people are faced with the invasion brought about a series of security problems. Employing game theory into a mobile Ad hoc network Intrusion Detection System (IDS) is presented in this paper. Network security game model is established, theoretical analysis and experiments of the Nash equilibrium solution of the model is yielded in this paper. Experimental results show that the model has effectively improved the detection rate and reduce the false detection rate, bringing the smaller network overhead. The effectiveness and feasibility of the method are proved.
With development of computer technology, especially Internet technology, people are faced with the invasion brought about a series of security problems. Employing game theory into a mobile Ad hoc network Intrusion Detection System (IDS) is presented in this paper. Network security game model is established, theoretical analysis and experiments of the Nash equilibrium solution of the model is yielded in this paper. Experimental results show that the model has effectively improved the detection rate and reduce the false detection rate, bringing the smaller network overhead. The effectiveness and feasibility of the method are proved.
2010, 32(9): 2249-2252.
doi: 10.3724/SP.J.1146.2009.01260
Abstract:
Certificateless signcryption key encapsulation mechanism (CLSC-KEM), combined with a data encapsulation mechanism, is used to construct certificateless hybrid signcryption . This paper introduces a new concept: certificateless signcryption KEM to multiple recipients (mCLSC-KEM). The definition and the security models are given for this new primitive, and a concrete mCLSC-KEM scheme is presented. This scheme is much more efficient than the generic construction, for it needs to compute only one pairing during key encapsulation and one symmetric encryption during data encapsulation, in contrast to n pairings and n symmetric encryptions for the generic scheme. Our scheme is provably secure in the random oracle model, under the hardness assumption of the Gap-BDH problem.
Certificateless signcryption key encapsulation mechanism (CLSC-KEM), combined with a data encapsulation mechanism, is used to construct certificateless hybrid signcryption . This paper introduces a new concept: certificateless signcryption KEM to multiple recipients (mCLSC-KEM). The definition and the security models are given for this new primitive, and a concrete mCLSC-KEM scheme is presented. This scheme is much more efficient than the generic construction, for it needs to compute only one pairing during key encapsulation and one symmetric encryption during data encapsulation, in contrast to n pairings and n symmetric encryptions for the generic scheme. Our scheme is provably secure in the random oracle model, under the hardness assumption of the Gap-BDH problem.
2010, 32(9): 2253-2257.
doi: 10.3724/SP.J.1146.2010.00145
Abstract:
Only the angle information of the targets can be obtained by infrared single-station. It is hard to get the distance information, which makes it impossible to track 3D objects in rectangular coordinates. A new algorithm is proposed for estimating the tracking parameters of bearings-only measurements, which avoids the complexity of traditional multi-station cross-location algorithms. According to the characteristics of high measurement rate by infrared sensors, azimuth sequences, obtained by an infrared single-station sensor, are utilized to measure the track parameters. Target tracking problems for single station could be solved effectively in such bearing-only mode. Simulation results show that the proposed algorithm has good filtering performance in tracking maneuvering targets, as well as the targets with straight-line motion.
Only the angle information of the targets can be obtained by infrared single-station. It is hard to get the distance information, which makes it impossible to track 3D objects in rectangular coordinates. A new algorithm is proposed for estimating the tracking parameters of bearings-only measurements, which avoids the complexity of traditional multi-station cross-location algorithms. According to the characteristics of high measurement rate by infrared sensors, azimuth sequences, obtained by an infrared single-station sensor, are utilized to measure the track parameters. Target tracking problems for single station could be solved effectively in such bearing-only mode. Simulation results show that the proposed algorithm has good filtering performance in tracking maneuvering targets, as well as the targets with straight-line motion.
2010, 32(9): 2258-2262.
doi: 10.3724/SP.J.1146.2009.01135
Abstract:
The anechoic chamber experiment is carried out to prove that in practical condition the thinned array aperture synthesis method can avoid the thinned array high sidelob, and the imaging algorithm based on compressed sensing theory can reconstruct the sparse target. For the array errors in experiment, the corresponding calibration methods are presented. Via experiment data processing, the validity of array error calibration method, the thinned array aperture synthesis method and the imaging algorithm based on compressed sensing theory are testified.
The anechoic chamber experiment is carried out to prove that in practical condition the thinned array aperture synthesis method can avoid the thinned array high sidelob, and the imaging algorithm based on compressed sensing theory can reconstruct the sparse target. For the array errors in experiment, the corresponding calibration methods are presented. Via experiment data processing, the validity of array error calibration method, the thinned array aperture synthesis method and the imaging algorithm based on compressed sensing theory are testified.
2010, 32(9): 2263-2267.
doi: 10.3724/SP.J.1146.2009.01256
Abstract:
In consideration of the the issue of the weakness performance of Compressive Sensing (CS) ISAR imaging under low SNR condition, an improved CS method is proposed in this paper. Energy based threshold is proposed to identify range cells containing only noise, a coherent projection in cross-range to improve the SNR of measurements then a iterative re-weighting norm optimization is applied to enhance the signal recovery while reject noise. Moreover, an advantage of this robustness is the ability to produce a high quality image and is suitable for ISAR imaging by using very limited echoes under strong noise and clutter. Experimental result of real data processing verifies the proposed methods capability of depressing noise or clutter and extracting strong scatterers to construct high resolution image. In the experiment, high quality image can be generated by using only 16 pulses and its robustness is confirmed too.
In consideration of the the issue of the weakness performance of Compressive Sensing (CS) ISAR imaging under low SNR condition, an improved CS method is proposed in this paper. Energy based threshold is proposed to identify range cells containing only noise, a coherent projection in cross-range to improve the SNR of measurements then a iterative re-weighting norm optimization is applied to enhance the signal recovery while reject noise. Moreover, an advantage of this robustness is the ability to produce a high quality image and is suitable for ISAR imaging by using very limited echoes under strong noise and clutter. Experimental result of real data processing verifies the proposed methods capability of depressing noise or clutter and extracting strong scatterers to construct high resolution image. In the experiment, high quality image can be generated by using only 16 pulses and its robustness is confirmed too.
2010, 32(9): 2268-2272.
doi: 10.3724/SP.J.1146.2009.01101
Abstract:
Raw data compression is an important step for high resolution SAR systems. This paper bases on two data compression methods, the 4 bit quantization and the 8 to 3 bit Block Adaptive Quantization (BAQ), which are widely used in spaceborne SAR, the evaluations are made on the Signal-to-Noise Ratio (SNR), the fidelity of the amplitude, and the vision effects of the images under different quantization input power. From the evaluations, the reasonable power regions of the quantization input for 4 bit and 8:3 bit BAQ are provided, which are 26.1 dB~34.9 dB and 23.5 dB~36.5 dB, respectively. This offers a good reference to the Manual Gain Control (MGC) value for the SAR mission.
Raw data compression is an important step for high resolution SAR systems. This paper bases on two data compression methods, the 4 bit quantization and the 8 to 3 bit Block Adaptive Quantization (BAQ), which are widely used in spaceborne SAR, the evaluations are made on the Signal-to-Noise Ratio (SNR), the fidelity of the amplitude, and the vision effects of the images under different quantization input power. From the evaluations, the reasonable power regions of the quantization input for 4 bit and 8:3 bit BAQ are provided, which are 26.1 dB~34.9 dB and 23.5 dB~36.5 dB, respectively. This offers a good reference to the Manual Gain Control (MGC) value for the SAR mission.
An Efficient Time Delay Estimation Algorithm for Multipath Signal of Distance Signal in TACAN System
2010, 32(9): 2273-2276.
doi: 10.3724/SP.J.1146.2009.01187
Abstract:
Based of known waveform, known period and concentrated energy of distance signal in TACAN system , an efficient time delay estimation algorithm for multipath signal of distance signal is presented in this paper, according to the former frequency spectral division algorithm. Firstly, the crosspower spectrum function is divided by frequency spectrum of referenced signal,. And the energy of out-of-band noise is not enhanced via using compensation factor. Then, the useful signal is restored from receiving signal via IFFT. Finally, the delay is estimated from restored signal. Its effectiveness is verified with the simulation results.
Based of known waveform, known period and concentrated energy of distance signal in TACAN system , an efficient time delay estimation algorithm for multipath signal of distance signal is presented in this paper, according to the former frequency spectral division algorithm. Firstly, the crosspower spectrum function is divided by frequency spectrum of referenced signal,. And the energy of out-of-band noise is not enhanced via using compensation factor. Then, the useful signal is restored from receiving signal via IFFT. Finally, the delay is estimated from restored signal. Its effectiveness is verified with the simulation results.
2010, 32(9): 2277-2281.
doi: 10.3724/SP.J.1146.2009.01242
Abstract:
For the issue of thinned array synthesis, an optimized design method of genetic algorithm based on integer code is proposed. By the application of individual description manner using integer coding, the search space is greatly reduced on the premise of elements thinned ratio is maintained constant. Base on the optimal array in elements position distribution, the weight is further optimized with convex optimization, which improves the main-side-ratio of array pattern significantly.The validity and superiority of method is confirmed by the result of the simulation data.
For the issue of thinned array synthesis, an optimized design method of genetic algorithm based on integer code is proposed. By the application of individual description manner using integer coding, the search space is greatly reduced on the premise of elements thinned ratio is maintained constant. Base on the optimal array in elements position distribution, the weight is further optimized with convex optimization, which improves the main-side-ratio of array pattern significantly.The validity and superiority of method is confirmed by the result of the simulation data.
2010, 32(9): 2282-2286.
doi: 10.3724/SP.J.1146.2009.01021
Abstract:
Conventional filters always suffer from the interference of its spurious bands, which leads to poor stopband in high frequency range. With the development of ultra-wide band radar system and ultra-wide band communication system, filters with minitype and wide-stopband become an urgent technique challenge. In this paper, a general design of miniature filter with ultra-wide stopband based on open-stub T-shaped structure is demonstrated. Comparing with conventional filters, this type of filters have compact structure, good passband characteristics and its spurious bands whtiin the fifth order harmonic frequency range are all suppressed. A lowpass filter with cutoff frequency at 2.9GHz is designed with the proposed structure. The measured average insertion loss is only 0.67dB, average VSWR is only 1.33. Its transition band is steep and its 40dB square ratio is 1.096. The measured 36dB stopband ranges from 3.23GHz to 10.30GHz and 27dB stopband ranges from 10.30GHz to 15GHz. Moreover, its length is only 37.1% of the conventional substitutional filter, with much less area and more compact layout. The simulated and measured results indicate that this open-stub T-shaped filter satisfies the demand of both minitype and wide-stopband.
Conventional filters always suffer from the interference of its spurious bands, which leads to poor stopband in high frequency range. With the development of ultra-wide band radar system and ultra-wide band communication system, filters with minitype and wide-stopband become an urgent technique challenge. In this paper, a general design of miniature filter with ultra-wide stopband based on open-stub T-shaped structure is demonstrated. Comparing with conventional filters, this type of filters have compact structure, good passband characteristics and its spurious bands whtiin the fifth order harmonic frequency range are all suppressed. A lowpass filter with cutoff frequency at 2.9GHz is designed with the proposed structure. The measured average insertion loss is only 0.67dB, average VSWR is only 1.33. Its transition band is steep and its 40dB square ratio is 1.096. The measured 36dB stopband ranges from 3.23GHz to 10.30GHz and 27dB stopband ranges from 10.30GHz to 15GHz. Moreover, its length is only 37.1% of the conventional substitutional filter, with much less area and more compact layout. The simulated and measured results indicate that this open-stub T-shaped filter satisfies the demand of both minitype and wide-stopband.
