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2009 Vol. 31, No. 1
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2009, 31(1): 1-4.
doi: 10.3724/SP.J.1146.2007.01632
Abstract:
Collision issue is a significant one which limits the reading efficiency of RFID systems. This paper presents two new anti-collision protocols - CDCA protocol and CDCA-2D protocol. Detailed theoretical analysis and optimization for the two protocols are provided in this paper. The new protocols split the reading process of RFID systems into two steps. The collision information is obtained in the first step and then applied to make the second reading step completely collision-free. The simulation results denote that the new proposed protocols highly improve the reading efficiency comparing to the current popular anti-collision algorithm.
Collision issue is a significant one which limits the reading efficiency of RFID systems. This paper presents two new anti-collision protocols - CDCA protocol and CDCA-2D protocol. Detailed theoretical analysis and optimization for the two protocols are provided in this paper. The new protocols split the reading process of RFID systems into two steps. The collision information is obtained in the first step and then applied to make the second reading step completely collision-free. The simulation results denote that the new proposed protocols highly improve the reading efficiency comparing to the current popular anti-collision algorithm.
2009, 31(1): 5-8.
doi: 10.3724/SP.J.1146.2007.01207
Abstract:
In this paper, multi-user diversity in the downlink channel of multi-user MIMO system is investigated and two multi-user scheduling algorithms are proposed which are based on the criteria of maximum system capacity. A factor based on inner products of channel vectors of relative users is used and complexity of scheduling procedure is greatly reduced. Simulation results are presented that multi-user scheduling methods enlarge system average capacity, and with the increase of the number of active users, multi-user scheduling gain grows gradually.
In this paper, multi-user diversity in the downlink channel of multi-user MIMO system is investigated and two multi-user scheduling algorithms are proposed which are based on the criteria of maximum system capacity. A factor based on inner products of channel vectors of relative users is used and complexity of scheduling procedure is greatly reduced. Simulation results are presented that multi-user scheduling methods enlarge system average capacity, and with the increase of the number of active users, multi-user scheduling gain grows gradually.
2009, 31(1): 9-12.
doi: 10.3724/SP.J.1146.2007.01077
Abstract:
This paper studies the estimation of slow time-varying frequency-selective MIMO wireless channel, which is described by the parameter of harmonic fitting model and presents a method of channel estimation based on harmonic retrieval of vector sequence and LS method with nonlinear constraints using training sequence. The method applied in this paper uses the identic sequence instead of chirp sequence. The simulation shows that this method has more simple training sequence and better estimation performance with same SNR in contrast to the method applying chirp sequence as training signals.
This paper studies the estimation of slow time-varying frequency-selective MIMO wireless channel, which is described by the parameter of harmonic fitting model and presents a method of channel estimation based on harmonic retrieval of vector sequence and LS method with nonlinear constraints using training sequence. The method applied in this paper uses the identic sequence instead of chirp sequence. The simulation shows that this method has more simple training sequence and better estimation performance with same SNR in contrast to the method applying chirp sequence as training signals.
2009, 31(1): 13-17.
doi: 10.3724/SP.J.1146.2007.01016
Abstract:
To meet the requirements of services with various quality of service in future broadband wireless communication systems, a satisfaction based scheduling scheme with hybrid beamforming strategy in multi-antenna downlink system is presented in this paper. This scheduler schedules users with joint considerations of users QoS requirements and channel quality. The Random beamforming and the Zero-forcing beamforming transmission schemes are selected according to satisfaction criterion. Punishment mechanism is proposed here to avoid users occupying too much more resource than their requirements. Simulation results show that the proposed strategy can guarantee users QoS requirements and exploit radio resource utilization better than that of the existed scheduling methods.
To meet the requirements of services with various quality of service in future broadband wireless communication systems, a satisfaction based scheduling scheme with hybrid beamforming strategy in multi-antenna downlink system is presented in this paper. This scheduler schedules users with joint considerations of users QoS requirements and channel quality. The Random beamforming and the Zero-forcing beamforming transmission schemes are selected according to satisfaction criterion. Punishment mechanism is proposed here to avoid users occupying too much more resource than their requirements. Simulation results show that the proposed strategy can guarantee users QoS requirements and exploit radio resource utilization better than that of the existed scheduling methods.
2009, 31(1): 18-22.
doi: 10.3724/SP.J.1146.2007.01060
Abstract:
Frequency Power Partition (FPP) scheme is proposed by considering the uniform distribution of the services among the cells. In FPP, the frequency reuse factor of one is used among the cells. In each cell, two third of the frequency is transmitted by the lower power; while the left is used by the higher power and orthogonal among the neighboring cells. According to the features of FPP, Influence-based Frequency Allocation (IFA) scheme and Profitability-and-Influence based Frequency Allocation (PIFA) scheme are proposed from the viewpoint of the throughput and the fairness, respectively. Finally, a simple power control scheme is designed by considering the uneven distribution of users and services in the cell. The simulation and analysis results indicate compared to the Soft Frequency Reuse (SFR), FPP+IFA and FPP+PIFA could obtain the large improvement on system throughput and fairness, respectively, and the power control scheme could improve the system throughput further when the users and services are distributed unevenly in the cell.
Frequency Power Partition (FPP) scheme is proposed by considering the uniform distribution of the services among the cells. In FPP, the frequency reuse factor of one is used among the cells. In each cell, two third of the frequency is transmitted by the lower power; while the left is used by the higher power and orthogonal among the neighboring cells. According to the features of FPP, Influence-based Frequency Allocation (IFA) scheme and Profitability-and-Influence based Frequency Allocation (PIFA) scheme are proposed from the viewpoint of the throughput and the fairness, respectively. Finally, a simple power control scheme is designed by considering the uneven distribution of users and services in the cell. The simulation and analysis results indicate compared to the Soft Frequency Reuse (SFR), FPP+IFA and FPP+PIFA could obtain the large improvement on system throughput and fairness, respectively, and the power control scheme could improve the system throughput further when the users and services are distributed unevenly in the cell.
2009, 31(1): 23-26.
doi: 10.3724/SP.J.1146.2007.01046
Abstract:
Due to the time variation and frequency offset of mobile radio channels of the OFDM system, the orthogonality between sub-carriers will be destroyed. In this paper, a novel phase rotation technique is proposed which can suppress the Inter-Carrier Interference (ICI) efficiently. This new method can get the minimum of sub-carrier interference in frequency domain by rotating the phase properly on each sub-carrier. Simulation results show that this new scheme can suppress the ICI efficiently and achieve better system BER performance, while the frequency efficiency and transmitting power remain the same.
Due to the time variation and frequency offset of mobile radio channels of the OFDM system, the orthogonality between sub-carriers will be destroyed. In this paper, a novel phase rotation technique is proposed which can suppress the Inter-Carrier Interference (ICI) efficiently. This new method can get the minimum of sub-carrier interference in frequency domain by rotating the phase properly on each sub-carrier. Simulation results show that this new scheme can suppress the ICI efficiently and achieve better system BER performance, while the frequency efficiency and transmitting power remain the same.
2009, 31(1): 27-31.
doi: 10.3724/SP.J.1146.2007.00997
Abstract:
In this paper, the channel capacity and the optimal resource allocation scheme for Distributed Alamouti Space-Time Code based on Decode-and-Forward (DF-DASTC) protocol are investigated. Using the degraded relay channel model, the channel capacity of DF-DASTC under fading channels is derived. To maximize the capacity of DF-DASTC, the closed-formed analytical expression of the optimal power allocation scheme with fixed bandwidth allocation is derived for DF-DASTC. Based on the convex optimization theory, the multi-objective optimization issue to maximize the capacity of DF-DASTC is converted into the general single objective optimization problem, and the optimal resource allocation scheme with variable bandwidth allocation is derived. Both theoretical analysis and simulations show that the resource allocation scheme can significantly increase the channel capacity of DF-DASTC. Moreover, the resource allocation scheme is a generalized method, which can be used in wireless relay networks with multiple relay nodes.
In this paper, the channel capacity and the optimal resource allocation scheme for Distributed Alamouti Space-Time Code based on Decode-and-Forward (DF-DASTC) protocol are investigated. Using the degraded relay channel model, the channel capacity of DF-DASTC under fading channels is derived. To maximize the capacity of DF-DASTC, the closed-formed analytical expression of the optimal power allocation scheme with fixed bandwidth allocation is derived for DF-DASTC. Based on the convex optimization theory, the multi-objective optimization issue to maximize the capacity of DF-DASTC is converted into the general single objective optimization problem, and the optimal resource allocation scheme with variable bandwidth allocation is derived. Both theoretical analysis and simulations show that the resource allocation scheme can significantly increase the channel capacity of DF-DASTC. Moreover, the resource allocation scheme is a generalized method, which can be used in wireless relay networks with multiple relay nodes.
2009, 31(1): 32-36.
doi: 10.3724/SP.J.1146.2007.01903
Abstract:
A limited feedback-based cooperative MIMO scheme is proposed to reduce the total energy consumption in Wireless Sensor Networks (WSNs). In this scheme based on the gradient algorithm, cluster head and cooperative cluster head can automatically adjust their power using one-bit feedback. For the cooperative MISO scheme based on Alamouti-code with limited feedback in WSNs, the bit-error-rate and the energy consumption is analyzed and its energy-consumption expression about Chernoff bound is derived. Analysis and numerical results show that the proposed cooperative MISO scheme consumes less energy than the cooperative MISO scheme based on standard Alamouti-code, and obtains high energy-efficiency. If the one is always chosen, which can provide better channel to transmit data, it will reduce more energy-consumption in WSNs.
A limited feedback-based cooperative MIMO scheme is proposed to reduce the total energy consumption in Wireless Sensor Networks (WSNs). In this scheme based on the gradient algorithm, cluster head and cooperative cluster head can automatically adjust their power using one-bit feedback. For the cooperative MISO scheme based on Alamouti-code with limited feedback in WSNs, the bit-error-rate and the energy consumption is analyzed and its energy-consumption expression about Chernoff bound is derived. Analysis and numerical results show that the proposed cooperative MISO scheme consumes less energy than the cooperative MISO scheme based on standard Alamouti-code, and obtains high energy-efficiency. If the one is always chosen, which can provide better channel to transmit data, it will reduce more energy-consumption in WSNs.
2009, 31(1): 37-40.
doi: 10.3724/SP.J.1146.2007.01157
Abstract:
In order to mitigate the effect of NLOS propagation, based on the Geometry Based Single- Bounced (GBSB)statistical model, a TOA/AOA location algorithm based on the RBF neural network is proposed. The fast study and non-linear approach capacity of the neural network is made use of to correct the error of NLOS propagation, then the position is calculated by Least-Square (LS) algorithm to improve the location[0] accuracy. The simulation results indicate that the location accuracy is significantly improved and the performance of this algorithm is better than that of Chan algorithm, Taylor algorithm and LS algorithm in NLOS environment.
In order to mitigate the effect of NLOS propagation, based on the Geometry Based Single- Bounced (GBSB)statistical model, a TOA/AOA location algorithm based on the RBF neural network is proposed. The fast study and non-linear approach capacity of the neural network is made use of to correct the error of NLOS propagation, then the position is calculated by Least-Square (LS) algorithm to improve the location[0] accuracy. The simulation results indicate that the location accuracy is significantly improved and the performance of this algorithm is better than that of Chan algorithm, Taylor algorithm and LS algorithm in NLOS environment.
2009, 31(1): 41-44.
doi: 10.3724/SP.J.1146.2007.01102
Abstract:
A QoS guaranteed dynamic resource allocation algorithm for downlink MIMO-OFDM systems is proposed based on the research on the issue of resource allocation in multiuser MIMO-OFDM systems. The proposed algorithm utilizes efficiently the spatio-frequency and power resources by taking full advantage of the multiuser diversity under the condition that the QoS requirements are guaranteed. So the system throughput is enhanced significantly. The simulation results demonstrate that the proposed scheme has good performance and can effectively enhance the system throughput.
A QoS guaranteed dynamic resource allocation algorithm for downlink MIMO-OFDM systems is proposed based on the research on the issue of resource allocation in multiuser MIMO-OFDM systems. The proposed algorithm utilizes efficiently the spatio-frequency and power resources by taking full advantage of the multiuser diversity under the condition that the QoS requirements are guaranteed. So the system throughput is enhanced significantly. The simulation results demonstrate that the proposed scheme has good performance and can effectively enhance the system throughput.
2009, 31(1): 45-48.
doi: 10.3724/SP.J.1146.2007.01205
Abstract:
A Particle Swarm Optimization (PSO) based Multiuser Detection (MUD) is proposed for the receive- diversity-aided and Space-Time Block Coded Multi-Carrier Code-Division Multiple-Access (STBC-MC-CDMA) systems. Due to the receive-diversity, the signals received at the different antennas are faded independently, resulting in an independent cost function for each antenna. To resolve the multi-objective dilemma when choosing one signal estimation for multiple receive antenna-branches, the virtual Pareto front is introduced, and each particle updates its velocity and position in a Pareto optimal way. Simulations show that the proposed scheme has the enhanced capabilities of exploration and exploitation and has better performance than the conventional PSO and multi-objective genetic algorithm.
A Particle Swarm Optimization (PSO) based Multiuser Detection (MUD) is proposed for the receive- diversity-aided and Space-Time Block Coded Multi-Carrier Code-Division Multiple-Access (STBC-MC-CDMA) systems. Due to the receive-diversity, the signals received at the different antennas are faded independently, resulting in an independent cost function for each antenna. To resolve the multi-objective dilemma when choosing one signal estimation for multiple receive antenna-branches, the virtual Pareto front is introduced, and each particle updates its velocity and position in a Pareto optimal way. Simulations show that the proposed scheme has the enhanced capabilities of exploration and exploitation and has better performance than the conventional PSO and multi-objective genetic algorithm.
2009, 31(1): 49-52.
doi: 10.3724/SP.J.1146.2007.01191
Abstract:
Linearly constrained Least Square Constant Modulus Algorithm (LSCMA) is an effective solution to the problem of interference capture in Constant Modulus Algorithm (CMA). But the performance will degrade when it is affected by the noise subspace in practical situations. In order to overcome this shortage, a subspace-based linearly constrained LSCMA multiuser detection algorithm is proposed. The proposed algorithm offers fast convergence rate, has good channel tracking ability and provides excellent output Signal-to-Interference-plus- Noise-Ratio (SINR) and Bit Error Rate (BER) performance. Theory analysis and simulation results demonstrate the effectiveness and superiority of the proposed algorithm.
Linearly constrained Least Square Constant Modulus Algorithm (LSCMA) is an effective solution to the problem of interference capture in Constant Modulus Algorithm (CMA). But the performance will degrade when it is affected by the noise subspace in practical situations. In order to overcome this shortage, a subspace-based linearly constrained LSCMA multiuser detection algorithm is proposed. The proposed algorithm offers fast convergence rate, has good channel tracking ability and provides excellent output Signal-to-Interference-plus- Noise-Ratio (SINR) and Bit Error Rate (BER) performance. Theory analysis and simulation results demonstrate the effectiveness and superiority of the proposed algorithm.
2009, 31(1): 53-56.
doi: 10.3724/SP.J.1146.2007.01189
Abstract:
In order to exploit multi-user diversity gain and spatial multiplexing gain for multi-user MIMO (Multiple-Input Multiple-Output) system with spatial correlation-aided Ricean fading channel, a joint multi-user precoding and scheduling algorithm is proposed based on partial Channel State Information (CSI). Utilizing partial instantaneous CSI and statistical CSI for all users, the Base Station (BS) estimates the channel for each user using Constrained Maximum Likelihood (CML) approach, and then schedules a group of users with optimal precoding using the estimated channels. Simulation results demonstrate that the proposed scheme greatly improves system throughput with a bit of feedback overhead.
In order to exploit multi-user diversity gain and spatial multiplexing gain for multi-user MIMO (Multiple-Input Multiple-Output) system with spatial correlation-aided Ricean fading channel, a joint multi-user precoding and scheduling algorithm is proposed based on partial Channel State Information (CSI). Utilizing partial instantaneous CSI and statistical CSI for all users, the Base Station (BS) estimates the channel for each user using Constrained Maximum Likelihood (CML) approach, and then schedules a group of users with optimal precoding using the estimated channels. Simulation results demonstrate that the proposed scheme greatly improves system throughput with a bit of feedback overhead.
2009, 31(1): 57-60.
doi: 10.3724/SP.J.1146.2007.01202
Abstract:
In this paper, the influence of error propagation on soft demodulation in coded MIMO system is analyzed in detail. Besides, based on the thought of soft symbol interference cancellation, Iterative Channel Soft Information (ICSI) for coded MIMO system is further deduced and proved to have the same form as the inverse of row norm of Moore-Penrose inverse of channel matrix. Theoretical analysis and simulation results indicate that the proposed coded MIMO detection algorithm based on ICSI could improve the system performance effectively without additional calculation complexity.
In this paper, the influence of error propagation on soft demodulation in coded MIMO system is analyzed in detail. Besides, based on the thought of soft symbol interference cancellation, Iterative Channel Soft Information (ICSI) for coded MIMO system is further deduced and proved to have the same form as the inverse of row norm of Moore-Penrose inverse of channel matrix. Theoretical analysis and simulation results indicate that the proposed coded MIMO detection algorithm based on ICSI could improve the system performance effectively without additional calculation complexity.
2009, 31(1): 61-65.
doi: 10.3724/SP.J.1146.2007.01044
Abstract:
In this paper, impact of SNR mismatch on the T-TCM performance is investigated in AWGN. The Monte Carlo simulation results indicate that when the under-estimate SNR offset is no more than 4dB, the T-TCM performance will not be badly affected, but greater offset can lead rapid performance degradation; Otherwise the overestimate of SNR will never lower the performance. A theoretical explanation is given by analyzing the Jacobian logarithm formula and iterative decoding algorithm, and based on the explanation a new T-TCM decoding scheme without SNR estimation is further proposed, with which the T-TCM systems have no performance loss and can be more conveniently applied and easily implemented.
In this paper, impact of SNR mismatch on the T-TCM performance is investigated in AWGN. The Monte Carlo simulation results indicate that when the under-estimate SNR offset is no more than 4dB, the T-TCM performance will not be badly affected, but greater offset can lead rapid performance degradation; Otherwise the overestimate of SNR will never lower the performance. A theoretical explanation is given by analyzing the Jacobian logarithm formula and iterative decoding algorithm, and based on the explanation a new T-TCM decoding scheme without SNR estimation is further proposed, with which the T-TCM systems have no performance loss and can be more conveniently applied and easily implemented.
2009, 31(1): 66-70.
doi: 10.3724/SP.J.1146.2007.01135
Abstract:
A novel scheme for JPEG2000 adaptive rate control is proposed based on rate pre-allocation and feedback control. After wavelet transform and quantification, a prediction module is introduced to estimate the entropy of EBCOT code block within available bit plane, then using the summation estimate entropy of each code block to allocate the rate for each code block. T2 encoder sends feedback to control the coding depth by the pre-allocation bit rate and complete the rate-distortion optimization truncation. The experimental results show that the proposed scheme can efficiently reduce the cost of computation and memory usage, which is suitable for hardware implementation with low computation.
A novel scheme for JPEG2000 adaptive rate control is proposed based on rate pre-allocation and feedback control. After wavelet transform and quantification, a prediction module is introduced to estimate the entropy of EBCOT code block within available bit plane, then using the summation estimate entropy of each code block to allocate the rate for each code block. T2 encoder sends feedback to control the coding depth by the pre-allocation bit rate and complete the rate-distortion optimization truncation. The experimental results show that the proposed scheme can efficiently reduce the cost of computation and memory usage, which is suitable for hardware implementation with low computation.
2009, 31(1): 71-74.
doi: 10.3724/SP.J.1146.2007.01079
Abstract:
The synchronization issue between unified chaotic system and its modified system is studied by employing intermittent feedback control. After properly designing intermittent feedback controller, the practical stability of synchronization systems is equivalent to that of the origin of the error dynamic system equation. A synchronization theorem, which satisfies the synchronization condition, is developed based on the stability theorem of the continuous systems and our simulation experiments. The synchronization performances with different initial value X(0) and Y(0), coefficient k, ratio D, step h and parameter are discussed in detail. A security communication system based on chaotic masking method is designed and simulated by applying the scheme of intermittent feedback synchronization. Simulation experiments proved the effectiveness of the synchronization approach.
The synchronization issue between unified chaotic system and its modified system is studied by employing intermittent feedback control. After properly designing intermittent feedback controller, the practical stability of synchronization systems is equivalent to that of the origin of the error dynamic system equation. A synchronization theorem, which satisfies the synchronization condition, is developed based on the stability theorem of the continuous systems and our simulation experiments. The synchronization performances with different initial value X(0) and Y(0), coefficient k, ratio D, step h and parameter are discussed in detail. A security communication system based on chaotic masking method is designed and simulated by applying the scheme of intermittent feedback synchronization. Simulation experiments proved the effectiveness of the synchronization approach.
2009, 31(1): 75-78.
doi: 10.3724/SP.J.1146.2007.00977
Abstract:
One of the main drawbacks of OFDM is its high sensitivity to phase noise (PHN). This gives rise to subcarriers phase rotation and InterCarrier Interference (ICI), so the orthogonality of subcarriers is destroyed. In this paper, an iterative PHN mitigation method is proposed. ICI coefficients are estimated in frequency domain by Huber ML estimator, and phase errors are mitigated in time domain samples by samples. The Huber ML estimator is robust to the propagation errors. Simulation results are reported in AWGN and multi-path channel models, which shows that the superior ICI mitigation performance of the proposed algorithm is achieved over the other available PHN mitigation methods.
One of the main drawbacks of OFDM is its high sensitivity to phase noise (PHN). This gives rise to subcarriers phase rotation and InterCarrier Interference (ICI), so the orthogonality of subcarriers is destroyed. In this paper, an iterative PHN mitigation method is proposed. ICI coefficients are estimated in frequency domain by Huber ML estimator, and phase errors are mitigated in time domain samples by samples. The Huber ML estimator is robust to the propagation errors. Simulation results are reported in AWGN and multi-path channel models, which shows that the superior ICI mitigation performance of the proposed algorithm is achieved over the other available PHN mitigation methods.
2009, 31(1): 79-82.
doi: 10.3724/SP.J.1146.2007.01103
Abstract:
In this paper, two typical high throughput decoding algorithms for QC-LDPC codes are presented: turbo-min-sum-product algorithm and parallel-weighted-bit-flipping algorithm. Their performance are compared in three aspects: decoding speed, hardware complexity, and error rate. In order to achieve high-throughput, a novel time scheduling for parallel-weighted-bit-flipping algorithm is proposed. Computer simulation confirms the effectiveness of two algorithms.
In this paper, two typical high throughput decoding algorithms for QC-LDPC codes are presented: turbo-min-sum-product algorithm and parallel-weighted-bit-flipping algorithm. Their performance are compared in three aspects: decoding speed, hardware complexity, and error rate. In order to achieve high-throughput, a novel time scheduling for parallel-weighted-bit-flipping algorithm is proposed. Computer simulation confirms the effectiveness of two algorithms.
2009, 31(1): 83-86.
doi: 10.3724/SP.J.1146.2007.01072
Abstract:
This paper brings up with a hardware structure optimized method which is suitable for high code rate LDPC decoder, for example, CCSDS recommended LDPC (Low-Density Parity-Check code) code with ?code rate of 7/8. LDPC code with high code rate is usually concomitant with problem that row weight is far larger than the column weight. This optimized method is based on check matrix splitting, it also optimizes the common components of parallel decoder structure, and reduces complexity imbalance between Check Node processing Units (CNUs) and Variable Node processing Units (VNUs) existed in high code rate LDPC decoder. Thus, clock performance of the decoder is improved. Experiment has proved, compared with usual partial parallel decode structure, structure provided by this paper saves 41% hardware resources, and the code rate of partial parallel decode structure which adopts the same amount of hardware resources is just 75% than code rate of the structure in this paper.
This paper brings up with a hardware structure optimized method which is suitable for high code rate LDPC decoder, for example, CCSDS recommended LDPC (Low-Density Parity-Check code) code with ?code rate of 7/8. LDPC code with high code rate is usually concomitant with problem that row weight is far larger than the column weight. This optimized method is based on check matrix splitting, it also optimizes the common components of parallel decoder structure, and reduces complexity imbalance between Check Node processing Units (CNUs) and Variable Node processing Units (VNUs) existed in high code rate LDPC decoder. Thus, clock performance of the decoder is improved. Experiment has proved, compared with usual partial parallel decode structure, structure provided by this paper saves 41% hardware resources, and the code rate of partial parallel decode structure which adopts the same amount of hardware resources is just 75% than code rate of the structure in this paper.
2009, 31(1): 87-90.
doi: 10.3724/SP.J.1146.2007.01070
Abstract:
Two low-complexity Particle Filtering (PF) detections for Multi-Input Multi-Output (MIMO) systems, namely sphere-constrained PF and multi-level mapping PF, are proposed by reducing the sample size and the search space of signal detection, respectively. In the proposed sphere-constrained PF, a sphere bound is first obtained based on zero-forcing principle, then the sphere bound is utilized to decrease the number of particles resulted by the importance sampling of each stage in the PF procedure. While the proposed multi-level mapping PF partitions the high-order Quadrature Amplitude Modulation (QAM) constellation of size 4L into L 4-QAM constellations with the aid of multi-level mapping, which reduces the search space of signal detection. Simulation results show that the first method can reduce the computational complexity of PF detection effectively without performance degradation especially when the number of transmit antennas is large; and the second method can significantly reduce the computational complexity at the cost of little performance degradation.
Two low-complexity Particle Filtering (PF) detections for Multi-Input Multi-Output (MIMO) systems, namely sphere-constrained PF and multi-level mapping PF, are proposed by reducing the sample size and the search space of signal detection, respectively. In the proposed sphere-constrained PF, a sphere bound is first obtained based on zero-forcing principle, then the sphere bound is utilized to decrease the number of particles resulted by the importance sampling of each stage in the PF procedure. While the proposed multi-level mapping PF partitions the high-order Quadrature Amplitude Modulation (QAM) constellation of size 4L into L 4-QAM constellations with the aid of multi-level mapping, which reduces the search space of signal detection. Simulation results show that the first method can reduce the computational complexity of PF detection effectively without performance degradation especially when the number of transmit antennas is large; and the second method can significantly reduce the computational complexity at the cost of little performance degradation.
2009, 31(1): 91-95.
doi: 10.3724/SP.J.1146.2007.01042
Abstract:
The maximization of data rate under the constraint of diversity gain, coding gain and total transmit power is a considerable issue in concatenated orthogonal space-time coding system. Based on the concatenated orthogonal space-time coding design criterion, this paper proposed a novel full-rate concatenated orthogonal space-time block codes with multiple trellis coded modulation approach. By introducing the power diversity factor, a new combining algorithm for maximum likelihood decoding is derived. Simulation are performed over the fast and the slow Rayleigh fading channels to demonstrate the 1dB coding gain of the proposed concatenated orthogonal space-time block codes with multiple trellis coded modulation schemes over the super orthogonal space-time coding schemes.
The maximization of data rate under the constraint of diversity gain, coding gain and total transmit power is a considerable issue in concatenated orthogonal space-time coding system. Based on the concatenated orthogonal space-time coding design criterion, this paper proposed a novel full-rate concatenated orthogonal space-time block codes with multiple trellis coded modulation approach. By introducing the power diversity factor, a new combining algorithm for maximum likelihood decoding is derived. Simulation are performed over the fast and the slow Rayleigh fading channels to demonstrate the 1dB coding gain of the proposed concatenated orthogonal space-time block codes with multiple trellis coded modulation schemes over the super orthogonal space-time coding schemes.
2009, 31(1): 96-100.
doi: 10.3724/SP.J.1146.2007.01166
Abstract:
A simplified particle filter algorithm, which introduces a compact threshold-based resampling algorithm and features lower computing power and hardware complexity, is proposed for the bearings-only tracking problem. Based on the proposed algorithm, this paper lays emphasis on the efficient hardware implementation of particle filters on FPGA platform, and presents the hardware architecture of the resample/sample unit and the whole system. Simulation results show that the simplified algorithm outperforms the extended Kalman filter. Experimental study indicates that the implemented particle filter can be used to solve the bearings-only tracking problem and has rather fast processing rate.
A simplified particle filter algorithm, which introduces a compact threshold-based resampling algorithm and features lower computing power and hardware complexity, is proposed for the bearings-only tracking problem. Based on the proposed algorithm, this paper lays emphasis on the efficient hardware implementation of particle filters on FPGA platform, and presents the hardware architecture of the resample/sample unit and the whole system. Simulation results show that the simplified algorithm outperforms the extended Kalman filter. Experimental study indicates that the implemented particle filter can be used to solve the bearings-only tracking problem and has rather fast processing rate.
2009, 31(1): 101-103.
doi: 10.3724/SP.J.1146.2007.01082
Abstract:
When the conventional virtual array is used for adaptive beamforming, the performance is largely influenced with the transforming area, even the serious distortion of the whole beam map will be aroused if an improper transforming area is chosen. This paper expressed an improvement solution based on subspace processing. With the presented algorithm, the interference null can be steadily formed. Meanwhile, it is not sensitive to which transforming area is chosen. On the other hand, this method can still form a good beam although there are a few snaps. Numerical examples attest the correctness and the validity of the proposed algorithm.
When the conventional virtual array is used for adaptive beamforming, the performance is largely influenced with the transforming area, even the serious distortion of the whole beam map will be aroused if an improper transforming area is chosen. This paper expressed an improvement solution based on subspace processing. With the presented algorithm, the interference null can be steadily formed. Meanwhile, it is not sensitive to which transforming area is chosen. On the other hand, this method can still form a good beam although there are a few snaps. Numerical examples attest the correctness and the validity of the proposed algorithm.
2009, 31(1): 104-107.
doi: 10.3724/SP.J.1146.2007.00979
Abstract:
Frequency tracking is a complex nonlinear problem, which is more difficult for the chaotic frequency modulation signal in which the traditional Extended Kalman Filter (EKF) can not work well. Thus, a new state space model for the frequency tracking is proposed, and the particle filter which can be used in nonlinear and non-Gaussian environments is introduced. Further more, the feasibility of the particle filter is analyzed, also the Posterior Cramer-Rao Bounds (PCRB) for the frequency tracking of the chaotic frequency modulation signal is derived. The simulation demonstrates the superiorities of particle filtering at last.
Frequency tracking is a complex nonlinear problem, which is more difficult for the chaotic frequency modulation signal in which the traditional Extended Kalman Filter (EKF) can not work well. Thus, a new state space model for the frequency tracking is proposed, and the particle filter which can be used in nonlinear and non-Gaussian environments is introduced. Further more, the feasibility of the particle filter is analyzed, also the Posterior Cramer-Rao Bounds (PCRB) for the frequency tracking of the chaotic frequency modulation signal is derived. The simulation demonstrates the superiorities of particle filtering at last.
2009, 31(1): 108-111.
doi: 10.3724/SP.J.1146.2007.00994
Abstract:
In this paper, the issue of blind image restoration is considered by using 2-D Great Common Divisor (GCD) extraction approach. A precise extraction algorithm of 2-D GCD is proposed. Since no high order ill-posed equation is needed, calculation complexity and noise robustness for the algorithm are improved. Simulation result shows that the proposed algorithm is able to provide a better performance than traditional algorithm.
In this paper, the issue of blind image restoration is considered by using 2-D Great Common Divisor (GCD) extraction approach. A precise extraction algorithm of 2-D GCD is proposed. Since no high order ill-posed equation is needed, calculation complexity and noise robustness for the algorithm are improved. Simulation result shows that the proposed algorithm is able to provide a better performance than traditional algorithm.
2009, 31(1): 112-115.
doi: 10.3724/SP.J.1146.2007.01039
Abstract:
Using image decomposition theory proposed by Meyer, a total variation image denoising method based on smoothing flow field is presented. Firstly, through applying Hilbert-Sobolev norm to measure fidelity term, a total variation filter is used to smooth the normal vectors of the level curves of a noise image. And then, a model is constructed to find a surface which fit smoothed normal vectors. Finally, finite difference schemes are used to solve the Euler-Lagrange functions derived from above models. The experiments show that the approach not only can remove noisy efficiently, but also can retain edges and texture.
Using image decomposition theory proposed by Meyer, a total variation image denoising method based on smoothing flow field is presented. Firstly, through applying Hilbert-Sobolev norm to measure fidelity term, a total variation filter is used to smooth the normal vectors of the level curves of a noise image. And then, a model is constructed to find a surface which fit smoothed normal vectors. Finally, finite difference schemes are used to solve the Euler-Lagrange functions derived from above models. The experiments show that the approach not only can remove noisy efficiently, but also can retain edges and texture.
2009, 31(1): 116-119.
doi: 10.3724/SP.J.1146.2007.00247
Abstract:
A feature representation method based on multi-layer local moment invariants for gait analysis and recognition applications is developed. The method includes following steps: first, silhouette extraction is performed for each image sequence. Secondly, the gait cycle is detected by a histogram-based approach. Thirdly, a scalarvalued CGHI(Colored Gait History Images) is proposed to describe how human walking is evolved. To improve the recognition rate, the CGHI is decomposed into a sequnce of muti-layer rectangle windows. The moment invariants from the window are used as the gait features and finally used to recognize gait. The correct classification rate of 87.2% is achieved on Soton database, which show that the method outperforms the exist methods.
A feature representation method based on multi-layer local moment invariants for gait analysis and recognition applications is developed. The method includes following steps: first, silhouette extraction is performed for each image sequence. Secondly, the gait cycle is detected by a histogram-based approach. Thirdly, a scalarvalued CGHI(Colored Gait History Images) is proposed to describe how human walking is evolved. To improve the recognition rate, the CGHI is decomposed into a sequnce of muti-layer rectangle windows. The moment invariants from the window are used as the gait features and finally used to recognize gait. The correct classification rate of 87.2% is achieved on Soton database, which show that the method outperforms the exist methods.
2009, 31(1): 120-123.
doi: 10.3724/SP.J.1146.2006.01509
Abstract:
A framework of reconstructing a super-resolution video sequence from a low resolution video sequence is proposed in this paper. First, an upsampling and deconvolution algorithm for single frame is introduced based on regularization by means of CG algorithm. Then after thoroughly studied the motion compensation matrix and weighted matrix, an adaptive filter is designed for the purpose of interframe data fusion based on weighted least square. Experimental results demonstrate the power of the proposed method with some adaptive and robust.
A framework of reconstructing a super-resolution video sequence from a low resolution video sequence is proposed in this paper. First, an upsampling and deconvolution algorithm for single frame is introduced based on regularization by means of CG algorithm. Then after thoroughly studied the motion compensation matrix and weighted matrix, an adaptive filter is designed for the purpose of interframe data fusion based on weighted least square. Experimental results demonstrate the power of the proposed method with some adaptive and robust.
2009, 31(1): 124-128.
doi: 10.3724/SP.J.1146.2007.01126
Abstract:
This paper researches the multiscal geometry analysis tool, NonSubsampled Contourlet Transform (NSCT), and proposes a new method of fusing panchromatic and multispectral images based on NSCT and Stationary Wavelet Transform (SWT). This method first performs NSCT on panchromatic image and the intensity component of multispectral image with IHS, then fuses the low frequency coefficients with SWT for further spatial information extraction, and fuses the high frequency coefficients based on local average gradient fusion rule, finally a fused image is obtained through inversing NSCT. The experimental results show that the proposed method can effectively preserve spectral information and improve spatial information of the fused image, and outperforms the traditional IHS, wavelet, DT-CWT and contourlet methods.
This paper researches the multiscal geometry analysis tool, NonSubsampled Contourlet Transform (NSCT), and proposes a new method of fusing panchromatic and multispectral images based on NSCT and Stationary Wavelet Transform (SWT). This method first performs NSCT on panchromatic image and the intensity component of multispectral image with IHS, then fuses the low frequency coefficients with SWT for further spatial information extraction, and fuses the high frequency coefficients based on local average gradient fusion rule, finally a fused image is obtained through inversing NSCT. The experimental results show that the proposed method can effectively preserve spectral information and improve spatial information of the fused image, and outperforms the traditional IHS, wavelet, DT-CWT and contourlet methods.
2009, 31(1): 129-133.
doi: 10.3724/SP.J.1146.2007.01014
Abstract:
Double Density Dual-Tree Complex Wavelet Transform (DDDTCWT) integrates the advantages of double density wavelet, dual tree wavelet and complex wavelet. It has translation invariability and improved directionality. When it is introduced to image fusion, the characteristics of original images are extracted better and more information for fusion is obtained. A novel image fusion method based on DDDTCWT is proposed in this paper. Firstly, the source images are decomposed using DDDTCWT, then the transform coefficients are fused with the fusion regular in the corresponding scales, and finally the fused coefficients are reconstructed to obtain fusion results. The proposed method is successfully used to merge several sets of multi-sensor images with different modalities. The experimental results indicate that the proposed approach can significantly outperform the traditional wavelet-transform-based image fusion method.
Double Density Dual-Tree Complex Wavelet Transform (DDDTCWT) integrates the advantages of double density wavelet, dual tree wavelet and complex wavelet. It has translation invariability and improved directionality. When it is introduced to image fusion, the characteristics of original images are extracted better and more information for fusion is obtained. A novel image fusion method based on DDDTCWT is proposed in this paper. Firstly, the source images are decomposed using DDDTCWT, then the transform coefficients are fused with the fusion regular in the corresponding scales, and finally the fused coefficients are reconstructed to obtain fusion results. The proposed method is successfully used to merge several sets of multi-sensor images with different modalities. The experimental results indicate that the proposed approach can significantly outperform the traditional wavelet-transform-based image fusion method.
2009, 31(1): 134-138.
doi: 10.3724/SP.J.1146.2007.01043
Abstract:
Watermark robustness to geometric attacks is still an open problem. This paper presents a new multi-bit image watermarking scheme that can resist Rotation, Scaling, Translation (RST), cropping as well as common signal processing attacks. The proposed scheme achieves watermark synchronization using Scale-Invariant Feature Transform (SIFT). The watermark is designed in a cirque pattern and it is embedded in spatial domain using odd-even quantization. An odd-even detector is designed to extract the watermark. Simulation results show that the proposed scheme achieves good image quality and it is robust to geometric attacks as well as traditional image compression, filtering operations.
Watermark robustness to geometric attacks is still an open problem. This paper presents a new multi-bit image watermarking scheme that can resist Rotation, Scaling, Translation (RST), cropping as well as common signal processing attacks. The proposed scheme achieves watermark synchronization using Scale-Invariant Feature Transform (SIFT). The watermark is designed in a cirque pattern and it is embedded in spatial domain using odd-even quantization. An odd-even detector is designed to extract the watermark. Simulation results show that the proposed scheme achieves good image quality and it is robust to geometric attacks as well as traditional image compression, filtering operations.
2009, 31(1): 139-142.
doi: 10.3724/SP.J.1146.2007.01108
Abstract:
This paper analyzes the statistical characteristics of radar clutter, discusses the K-distributed random process used for describing the amplitude characteristics of the clutter, deduces the formulas of relation between K-distributed and Gamma-distributed random variables, and presents a novel method for estimating parameters of K-distributed clutter. Finally, the simulation experimental results of generating the clutter samples and estimating the parameters prove the conclusion proposed.
This paper analyzes the statistical characteristics of radar clutter, discusses the K-distributed random process used for describing the amplitude characteristics of the clutter, deduces the formulas of relation between K-distributed and Gamma-distributed random variables, and presents a novel method for estimating parameters of K-distributed clutter. Finally, the simulation experimental results of generating the clutter samples and estimating the parameters prove the conclusion proposed.
2009, 31(1): 143-146.
doi: 10.3724/SP.J.1146.2007.01087
Abstract:
Passive radar imaging algorithm based on external illuminator requires large accumulated rotating angle of target. But in an actual circumstance, large rotating angle demands long time， which is hard to satisfy the request of real time，on the other hand，target reflectivity function differs at various aspect angles，Moreover， when rotating angle increases，target reflectivity function differs seriously. In this paper, an ESPRIT based high resolution passive radar imaging algorithm is proposed to solve the problem which is that how to form a good image at the instant of small rotating angle. In the method self-correlation matrix of the returned echoes is estimated firstly，then corresponding sine wave frequencies of the scattering-centers with the object is determined through eigenvalue decomposition，target location is deduced with the sine wave frequency，hence the reflectivity of the scattering-centers are computed. Computer simulation confirms the feasibility of the algorithm.
Passive radar imaging algorithm based on external illuminator requires large accumulated rotating angle of target. But in an actual circumstance, large rotating angle demands long time， which is hard to satisfy the request of real time，on the other hand，target reflectivity function differs at various aspect angles，Moreover， when rotating angle increases，target reflectivity function differs seriously. In this paper, an ESPRIT based high resolution passive radar imaging algorithm is proposed to solve the problem which is that how to form a good image at the instant of small rotating angle. In the method self-correlation matrix of the returned echoes is estimated firstly，then corresponding sine wave frequencies of the scattering-centers with the object is determined through eigenvalue decomposition，target location is deduced with the sine wave frequency，hence the reflectivity of the scattering-centers are computed. Computer simulation confirms the feasibility of the algorithm.
2009, 31(1): 147-151.
doi: 10.3724/SP.J.1146.2008.00045
Abstract:
Multi-carrier MIMO radar is a radar system with multiple transmitted antennas and multiple received antennas capitalizing on frequency diversity and spatial diversity to obtain orthogonality of transmitted signals and the methods based on the dechirp processing to obtain High Range Resolution (HRR) are studied in this paper. The IFFT coherent synthesis processing method and the excuse of spurious peaks are analyzed and then a novel signal processing method, Spatial Domain Synthetic Bandwidth (SDSB) approach, is proposed. The multiple carrier frequency LFM return signals transmitted spatially diversity are first deramped by the dechirp processing and then the individual channel signals after the channel separation are combined into an LFM signal with a larger bandwidth by time shift in sequence. Finally the IFFT processing is applied to the concatenated signal to achieve HRR. The approach can be implemented easily, can avoid the spurious peaks effectively without the addition of computation and has a slightly influence on the moving target. Finally the simulation results on the computer validate these conclusions.
Multi-carrier MIMO radar is a radar system with multiple transmitted antennas and multiple received antennas capitalizing on frequency diversity and spatial diversity to obtain orthogonality of transmitted signals and the methods based on the dechirp processing to obtain High Range Resolution (HRR) are studied in this paper. The IFFT coherent synthesis processing method and the excuse of spurious peaks are analyzed and then a novel signal processing method, Spatial Domain Synthetic Bandwidth (SDSB) approach, is proposed. The multiple carrier frequency LFM return signals transmitted spatially diversity are first deramped by the dechirp processing and then the individual channel signals after the channel separation are combined into an LFM signal with a larger bandwidth by time shift in sequence. Finally the IFFT processing is applied to the concatenated signal to achieve HRR. The approach can be implemented easily, can avoid the spurious peaks effectively without the addition of computation and has a slightly influence on the moving target. Finally the simulation results on the computer validate these conclusions.
2009, 31(1): 152-155.
doi: 10.3724/SP.J.1146.2007.01181
Abstract:
Synthetic Aperture Radar (SAR) using multiple transmit-receive apertures can obtain wider swath and higher spatial resolution. In this paper, intersection of frequency spectrum is adopted in the SAR imaging using multiple transmit-receive apertures, which can achieve high range and azimuth resolution simultaneously. As for sub-band pulses synchronously transmit-received, a method of sub-band combination in time domain prior to pulse-compression is proposed and sub-band compression prior to combining is proposed in frequency domain as a extension. The simulation result illustrates the validity of these methods. In addition, there exist some phase differences caused by the carrier frequency and their influence on pulse compression and SAR imaging is studied, the computer simulation is made to show the influence.
Synthetic Aperture Radar (SAR) using multiple transmit-receive apertures can obtain wider swath and higher spatial resolution. In this paper, intersection of frequency spectrum is adopted in the SAR imaging using multiple transmit-receive apertures, which can achieve high range and azimuth resolution simultaneously. As for sub-band pulses synchronously transmit-received, a method of sub-band combination in time domain prior to pulse-compression is proposed and sub-band compression prior to combining is proposed in frequency domain as a extension. The simulation result illustrates the validity of these methods. In addition, there exist some phase differences caused by the carrier frequency and their influence on pulse compression and SAR imaging is studied, the computer simulation is made to show the influence.
2009, 31(1): 156-159.
doi: 10.3724/SP.J.1146.2007.01110
Abstract:
Accurate motion compensation is a key issue for high-resolution airborne SAR imaging. In order to attain high-quality squint SAR images, it is detailedly discussed that Extended Wavenumber Domain (EWD) algorithm combines two-step motion compensation technique processing squint SAR data affected by motion error in the paper，a kind of method of squint EWD algorithm is put forward, simulation and real SAR data processing results with this method are given to prove the feasibility of such algorithm.
Accurate motion compensation is a key issue for high-resolution airborne SAR imaging. In order to attain high-quality squint SAR images, it is detailedly discussed that Extended Wavenumber Domain (EWD) algorithm combines two-step motion compensation technique processing squint SAR data affected by motion error in the paper，a kind of method of squint EWD algorithm is put forward, simulation and real SAR data processing results with this method are given to prove the feasibility of such algorithm.
2009, 31(1): 160-163.
doi: 10.3724/SP.J.1146.2007.01041
Abstract:
A modified ACCA-CFAR method with local adaptive threshold is proposed for SAR image detection based on ACCA-CFAR in this paper, in which the K-distribution is used to describe the clutter. First the parameter of K-distribution is estimated, secondly, the local ODV (Ordered Data Variability) threshold is determined and the background pixels are selected, finally the detection is made. The paper also proves that the ODV threshold is related with the parameter of the local statistical model. Finally, the algorithm is applied to SAR image of ship, and the result indicates that there are fewer false alarms in the new algorithm, and the whole ship targets are detected with more structure details.
A modified ACCA-CFAR method with local adaptive threshold is proposed for SAR image detection based on ACCA-CFAR in this paper, in which the K-distribution is used to describe the clutter. First the parameter of K-distribution is estimated, secondly, the local ODV (Ordered Data Variability) threshold is determined and the background pixels are selected, finally the detection is made. The paper also proves that the ODV threshold is related with the parameter of the local statistical model. Finally, the algorithm is applied to SAR image of ship, and the result indicates that there are fewer false alarms in the new algorithm, and the whole ship targets are detected with more structure details.
2009, 31(1): 164-168.
doi: 10.3724/SP.J.1146.2008.00416
Abstract:
The improved fractal feature of each pixel can be extracted based on the filtered image using the exponential wavelet at one scale and energy functions. This paper studies the method of the improved fractal feature for SAR images target detection. The results of target detections using the improved fractal feature are compared with that using the method of Extended Fractal (EF) for SAR images in the simple and complex backgrounds respectively. Results state the method using the improved fractal feature can not only detect all size-fixed targets but also have lower false alarm rates, spatial resolution of the detected targets are higher and the locations of the detected targets are more accurate in both of the backgrounds, but worse false alarm rates in complex background than in the simple background using the improved fractal feature.
The improved fractal feature of each pixel can be extracted based on the filtered image using the exponential wavelet at one scale and energy functions. This paper studies the method of the improved fractal feature for SAR images target detection. The results of target detections using the improved fractal feature are compared with that using the method of Extended Fractal (EF) for SAR images in the simple and complex backgrounds respectively. Results state the method using the improved fractal feature can not only detect all size-fixed targets but also have lower false alarm rates, spatial resolution of the detected targets are higher and the locations of the detected targets are more accurate in both of the backgrounds, but worse false alarm rates in complex background than in the simple background using the improved fractal feature.
2009, 31(1): 169-172.
doi: 10.3724/SP.J.1146.2007.01107
Abstract:
Ultra-WideBand Synthetic Aperture Radar (UWB SAR) can detect shallow buried UneXploded Ordnance (UXO), where the efficiency of extracted features determines the detection performance. The traditional subband-subaperture processing extracts the frequency and aspect information of UXO scattering with sacrifice of spatial resolutions. According to the issue, in this paper, the frequency and aspect angle features extraction method is proposed on the Space-Wavenumber Distribution (SWD), which is combined with the moment invariants to obtain the shift- and rotation-invariant feature set. The proposed feature set contains not only the frequency and aspect information but also high spatial resolutions information. Field data processing results show that the proposed features in this paper can improve the UXO detection performance efficiently.
Ultra-WideBand Synthetic Aperture Radar (UWB SAR) can detect shallow buried UneXploded Ordnance (UXO), where the efficiency of extracted features determines the detection performance. The traditional subband-subaperture processing extracts the frequency and aspect information of UXO scattering with sacrifice of spatial resolutions. According to the issue, in this paper, the frequency and aspect angle features extraction method is proposed on the Space-Wavenumber Distribution (SWD), which is combined with the moment invariants to obtain the shift- and rotation-invariant feature set. The proposed feature set contains not only the frequency and aspect information but also high spatial resolutions information. Field data processing results show that the proposed features in this paper can improve the UXO detection performance efficiently.
2009, 31(1): 173-176.
doi: 10.3724/SP.J.1146.2007.01066
Abstract:
Based on the analysis of bistatic SAR geometry model, bistatic SAR echoed signal is modeled in the double range variables domain in this paper, and the relationship between the double range variable domain and the single range variable domain is established. Then a range-dependent Doppler algorithm for imaging processing airborne bistatic SAR raw data of the translationally invariant configuration is derived, and the effect of error of the algorithm is analyzed by simulating. The algorithm is also tested with real data, and the advantage of the algorithm is proved by the comparison with bistatic SAR traditional RD algorithm.
Based on the analysis of bistatic SAR geometry model, bistatic SAR echoed signal is modeled in the double range variables domain in this paper, and the relationship between the double range variable domain and the single range variable domain is established. Then a range-dependent Doppler algorithm for imaging processing airborne bistatic SAR raw data of the translationally invariant configuration is derived, and the effect of error of the algorithm is analyzed by simulating. The algorithm is also tested with real data, and the advantage of the algorithm is proved by the comparison with bistatic SAR traditional RD algorithm.
2009, 31(1): 177-181.
doi: 10.3724/SP.J.1146.2007.01111
Abstract:
Many traditional target extraction methods encountered a new challenge as the spatial resolution is increasing quickly. For the purpose of extracting buildings automatically in that circumstance, a new method combing both the object-based approach and boosting algorithm is proposed in this paper. The method associates segmentation with recognition by constructing a hierarchical object network, which improves effectively the problem of detecting targets with a modifiable sliding window existed in other methods. Then some useful features are selected automatically to train a validate classifier, and the confidence in each label incorporating kinds of information is computed to complete the extraction procedure. Competitive results both for multiform and complicated buildings demonstrate the precision, robustness and effectiveness of the proposed method.
Many traditional target extraction methods encountered a new challenge as the spatial resolution is increasing quickly. For the purpose of extracting buildings automatically in that circumstance, a new method combing both the object-based approach and boosting algorithm is proposed in this paper. The method associates segmentation with recognition by constructing a hierarchical object network, which improves effectively the problem of detecting targets with a modifiable sliding window existed in other methods. Then some useful features are selected automatically to train a validate classifier, and the confidence in each label incorporating kinds of information is computed to complete the extraction procedure. Competitive results both for multiform and complicated buildings demonstrate the precision, robustness and effectiveness of the proposed method.
2009, 31(1): 182-187.
doi: 10.3724/SP.J.1146.2007.01104
Abstract:
Making use of bistatic SAR image simulation, polarimetric characteristics of BISAR image are studied. It is found that some conventional polarimetric parameters, such as Cloudes , ,, for interpretation of monostatic SAR image lose their effectiveness for bistatic case. A transform of the unified bistatic polar bases for BISAR image is presented, and the polarimetric parameters, i.e. ,,, are redefined to preserve their merits of orientation independence. Image simulations show that the polarimetric characteristics of different terrain surfaces are well described using these unified bistatic polar bases, and newly redefined ,, are also applicable to interpret different scattering mechanism. It provides a new way for bistatic image interpretation and information retrievals.
Making use of bistatic SAR image simulation, polarimetric characteristics of BISAR image are studied. It is found that some conventional polarimetric parameters, such as Cloudes , ,, for interpretation of monostatic SAR image lose their effectiveness for bistatic case. A transform of the unified bistatic polar bases for BISAR image is presented, and the polarimetric parameters, i.e. ,,, are redefined to preserve their merits of orientation independence. Image simulations show that the polarimetric characteristics of different terrain surfaces are well described using these unified bistatic polar bases, and newly redefined ,, are also applicable to interpret different scattering mechanism. It provides a new way for bistatic image interpretation and information retrievals.
2009, 31(1): 188-191.
doi: 10.3724/SP.J.1146.2007.01167
Abstract:
To enhance accurate recognition rate of radar emitter signals to meet the requirements of modern electronic warfare, a novel method for radar emitter signals recognition is presented in this paper. Based on the over-complete multiscale dictionary of Spectrum atoms, the signal are decomposed into a linear expansion of atoms by the method of Matching Pursuit(MP), and FFT is applied to effectively reduce the time-complexity at each step of MP. Then the atoms characteristics vector can be achieved to identify radar emitter signals automatically and estimate the signal parameters synchronously. Experiment results show that the method can achieve high accurate recognition rate and valid parameters estimation in the circumstance of lower SNR, which confirms the properties of the proposed approach.
To enhance accurate recognition rate of radar emitter signals to meet the requirements of modern electronic warfare, a novel method for radar emitter signals recognition is presented in this paper. Based on the over-complete multiscale dictionary of Spectrum atoms, the signal are decomposed into a linear expansion of atoms by the method of Matching Pursuit(MP), and FFT is applied to effectively reduce the time-complexity at each step of MP. Then the atoms characteristics vector can be achieved to identify radar emitter signals automatically and estimate the signal parameters synchronously. Experiment results show that the method can achieve high accurate recognition rate and valid parameters estimation in the circumstance of lower SNR, which confirms the properties of the proposed approach.
2009, 31(1): 192-195.
doi: 10.3724/SP.J.1146.2007.01118
Abstract:
In the situation of sample pollution, nulls would be formed in the expected direction, which results a great decrease in the signal-to-interference-noise ratio. And in the situation of limited snapshots, the given white noise exists in the form of color noise, so that there would be an increase in the distortion of adaptive beamforming. Based on these, an adaptive method is presented in this paper by analyzing the eigenvalues of sampling covariance matrix. This method is equivalent to interfering the sampling covariance matrix in order to improve the performance and robustness of beamforming. Finally, performance analysis and computer simulation demonstrate the feasibility and effectiveness of this method.
In the situation of sample pollution, nulls would be formed in the expected direction, which results a great decrease in the signal-to-interference-noise ratio. And in the situation of limited snapshots, the given white noise exists in the form of color noise, so that there would be an increase in the distortion of adaptive beamforming. Based on these, an adaptive method is presented in this paper by analyzing the eigenvalues of sampling covariance matrix. This method is equivalent to interfering the sampling covariance matrix in order to improve the performance and robustness of beamforming. Finally, performance analysis and computer simulation demonstrate the feasibility and effectiveness of this method.
The Study of Integrity Monitor Algorithm of the Pseudorange Correction Error on LAAS Ground Facility
2009, 31(1): 196-200.
doi: 10.3724/SP.J.1146.2007.01006
Abstract:
The formulas of the pseudorange correction error are deduced. The existing integrity monitor method of the pseudorange correction error with excluding B value is analyzed, and some conclusions are obtained: the B values are correlative, if one B value is error, the other B values will be affected; the receiver error and the satellite error are not divided in the existing method, so the larger probability of fault detection and miss detection will occur. Two new methods are proposed to monitor the pseudorange correction error, which are named row and column estimation and assisting by C value. Analysis about the three methods is made by simulating six cases including no fault and five kinds faults, the results show that the two new methods probability of fault detection, miss detection, fault exclusion, miss exclusion are all smaller than the existing methods. Moreover, the position accuracy and continuity are improved. The two new methods are compared, and their advantage and disadvantage are discussed. Some suggestions are proposed on choosing methods.
The formulas of the pseudorange correction error are deduced. The existing integrity monitor method of the pseudorange correction error with excluding B value is analyzed, and some conclusions are obtained: the B values are correlative, if one B value is error, the other B values will be affected; the receiver error and the satellite error are not divided in the existing method, so the larger probability of fault detection and miss detection will occur. Two new methods are proposed to monitor the pseudorange correction error, which are named row and column estimation and assisting by C value. Analysis about the three methods is made by simulating six cases including no fault and five kinds faults, the results show that the two new methods probability of fault detection, miss detection, fault exclusion, miss exclusion are all smaller than the existing methods. Moreover, the position accuracy and continuity are improved. The two new methods are compared, and their advantage and disadvantage are discussed. Some suggestions are proposed on choosing methods.
2009, 31(1): 201-205.
doi: 10.3724/SP.J.1146.2007.00995
Abstract:
In order to reduce energy consumption of nodes in the wireless ad hoc networks, a Power Control Algorithm based on Position of node (PCAP) is proposed. By analyzing the relationship between nodes, the Optimized Neighbor Set (ONS) of node is built. PCAP uses different power control policies for routing packets, control packets of MAC layer and other data packets. PCAP algorithm can reduce the energy consumption and guarantee the connectivity of network. The simulation results indicate that it can achieve well network performance, such as the throughput of MAC layer, dropped packets and end to end delay.
In order to reduce energy consumption of nodes in the wireless ad hoc networks, a Power Control Algorithm based on Position of node (PCAP) is proposed. By analyzing the relationship between nodes, the Optimized Neighbor Set (ONS) of node is built. PCAP uses different power control policies for routing packets, control packets of MAC layer and other data packets. PCAP algorithm can reduce the energy consumption and guarantee the connectivity of network. The simulation results indicate that it can achieve well network performance, such as the throughput of MAC layer, dropped packets and end to end delay.
2009, 31(1): 206-209.
doi: 10.3724/SP.J.1146.2007.01178
Abstract:
Wavelength-Division-Multiplexing (WDM) multi-granularity traffic switching all-optical network is the evolution direction of the recent optical transport networks. In this paper, the practical WDM multi-granularity traffic switching testing network is constructed and a novel method using eye diagram to monitor optical performance in the network is proposed. The method is demonstrated in the reconfigurable WDM multi-granularity traffic switching all-optical network and it results that it can realize supervision of optical signal to noise ratio, time jittering, channel power, extinction ratio and bit error rate of optical data stream of any wavelength channel in the network. The method is transparent to signal protocol and bit rates and is able to distinguish between different optical impairments.
Wavelength-Division-Multiplexing (WDM) multi-granularity traffic switching all-optical network is the evolution direction of the recent optical transport networks. In this paper, the practical WDM multi-granularity traffic switching testing network is constructed and a novel method using eye diagram to monitor optical performance in the network is proposed. The method is demonstrated in the reconfigurable WDM multi-granularity traffic switching all-optical network and it results that it can realize supervision of optical signal to noise ratio, time jittering, channel power, extinction ratio and bit error rate of optical data stream of any wavelength channel in the network. The method is transparent to signal protocol and bit rates and is able to distinguish between different optical impairments.
2009, 31(1): 210-214.
doi: 10.3724/SP.J.1146.2007.01134
Abstract:
To eliminate the affect of the change of resource information on the QoS multicast routing, an algorithm for Distributed QoS Multicast Routing with Resource Reservation(DQMTR) is put forward in this paper. Using resource reservation in the process of path-detecting, DQMTR overcomes the issue. By noting the number of reserved resource, DQMTR resolves the issue of over-reservation. This paper considers the characteristic of differentiated services model to which DQMTR is adapted. The simulation reveals that the algorithm improves the success ratio, and optimizes the average path cost.
To eliminate the affect of the change of resource information on the QoS multicast routing, an algorithm for Distributed QoS Multicast Routing with Resource Reservation(DQMTR) is put forward in this paper. Using resource reservation in the process of path-detecting, DQMTR overcomes the issue. By noting the number of reserved resource, DQMTR resolves the issue of over-reservation. This paper considers the characteristic of differentiated services model to which DQMTR is adapted. The simulation reveals that the algorithm improves the success ratio, and optimizes the average path cost.
2009, 31(1): 215-218.
doi: 10.3724/SP.J.1146.2007.01047
Abstract:
Scheme of opportunistic cooperation transmission and its performance in wireless sensor network is studied based on Nakagami channel in this paper, and effect of circuit power on the scheme is also researched. Three issues including how to cooperation, when to cooperation and performance of cooperation are solved. And probability of opportunistic cooperation is discussed from theory. Simulation results show that opportunistic cooperation transmission can reach better performance than direct transmission, and circuit power of sensor node also has great effect on system performance.
Scheme of opportunistic cooperation transmission and its performance in wireless sensor network is studied based on Nakagami channel in this paper, and effect of circuit power on the scheme is also researched. Three issues including how to cooperation, when to cooperation and performance of cooperation are solved. And probability of opportunistic cooperation is discussed from theory. Simulation results show that opportunistic cooperation transmission can reach better performance than direct transmission, and circuit power of sensor node also has great effect on system performance.
2009, 31(1): 219-223.
doi: 10.3724/SP.J.1146.2007.01094
Abstract:
The conflict interference issue of the carrier sensing wireless network is investigated, and an adaptive power control mechanism of DCF protocol in Ad hoc networks is proposed. According to the communication status of the receiver, this mechanism adjusts adaptively the CTS frame transmission power of the receiver and the data frame transmission power of the transmitter which is decided by the receiver. The simulation results show that DCF protocol with this mechanism can not only save the average energy consumption of the nodes, thus prolong the lifetime of the network, but also can improve spatial reuse of the wireless channel, and improve the average throughput of the network significantly.
The conflict interference issue of the carrier sensing wireless network is investigated, and an adaptive power control mechanism of DCF protocol in Ad hoc networks is proposed. According to the communication status of the receiver, this mechanism adjusts adaptively the CTS frame transmission power of the receiver and the data frame transmission power of the transmitter which is decided by the receiver. The simulation results show that DCF protocol with this mechanism can not only save the average energy consumption of the nodes, thus prolong the lifetime of the network, but also can improve spatial reuse of the wireless channel, and improve the average throughput of the network significantly.
2009, 31(1): 224-227.
doi: 10.3724/SP.J.1146.2007.01519
Abstract:
Principals establish trust relationship by iterative disclosure of credentials and access control policies in trust negotiation. The policies and credentials might be protected because the policies might not be revealed directly and credentials possessions are the privacy for the principals. In this paper, a Policy-Based Signature Scheme (PBSS) is proposed, which protect subset of credentials in according to policy using identity-based ring signature scheme. Verifier can get the proof that signer owned credentials in according to specified policy, where signer can not deduce what types credentials supply for. Security and correctness proofs are given in random oracle model with BDH problem assumption. PBSS is only two pairings calculation and irrelevant to policy expression and size of credential set. Compared with Proof-Carrying Proxy Certificates (PCPC) scheme which proposed by Bagga(2006), the proposed PBSS scheme has higher computing efficient and lower bandwidth consumption costs than the later.
Principals establish trust relationship by iterative disclosure of credentials and access control policies in trust negotiation. The policies and credentials might be protected because the policies might not be revealed directly and credentials possessions are the privacy for the principals. In this paper, a Policy-Based Signature Scheme (PBSS) is proposed, which protect subset of credentials in according to policy using identity-based ring signature scheme. Verifier can get the proof that signer owned credentials in according to specified policy, where signer can not deduce what types credentials supply for. Security and correctness proofs are given in random oracle model with BDH problem assumption. PBSS is only two pairings calculation and irrelevant to policy expression and size of credential set. Compared with Proof-Carrying Proxy Certificates (PCPC) scheme which proposed by Bagga(2006), the proposed PBSS scheme has higher computing efficient and lower bandwidth consumption costs than the later.
2009, 31(1): 228-232.
Abstract:
A game-theoretic analysis of security interactive behavior is performed between the DoS attacker and the defender under incomplete information. The dilemma of defense is discussed and the underlying fact is revealed that asymmetric nature of information and absence of server-user coalition lead to the dilemma. An improved DoS game is performed which can acquire new equilibrium through service hopping tactic, increasing service type and establishing the server-user coalition. Theoretical analysis shows that service hopping tactic is active and efficient for DoS defense. It is fundamental and important for service hopping mechanism and DoS defense.
A game-theoretic analysis of security interactive behavior is performed between the DoS attacker and the defender under incomplete information. The dilemma of defense is discussed and the underlying fact is revealed that asymmetric nature of information and absence of server-user coalition lead to the dilemma. An improved DoS game is performed which can acquire new equilibrium through service hopping tactic, increasing service type and establishing the server-user coalition. Theoretical analysis shows that service hopping tactic is active and efficient for DoS defense. It is fundamental and important for service hopping mechanism and DoS defense.
2009, 31(1): 233-237.
doi: 10.3724/SP.J.1146.2007.01574
Abstract:
The electromagnetic wave transmission with plane wave incidence on the rough surface of layered medium is studied, the formulae of the transmission coefficient for different polarization is derived using the small perturbation method. A 2-D fBm fractal rough surface is presented for describing natural rough surface of layered medium, the curves of the transmission coefficient of the HH polarization with varying of the scattering angle of transmission wave are obtained by numerical implementation, the fractal characteristics, the basic characteristics, and the characteristics with varying of frequency of the incidence wave are obtained by numerical calculating. The numerical results show that the influence of the fractal dimension, the permittivity of substrate medium, the permittivity and the mean layer thickness of intermediate medium, the rms and the correlation length of the rough surface, and the incident frequency on the transmission coefficient is very complex.
The electromagnetic wave transmission with plane wave incidence on the rough surface of layered medium is studied, the formulae of the transmission coefficient for different polarization is derived using the small perturbation method. A 2-D fBm fractal rough surface is presented for describing natural rough surface of layered medium, the curves of the transmission coefficient of the HH polarization with varying of the scattering angle of transmission wave are obtained by numerical implementation, the fractal characteristics, the basic characteristics, and the characteristics with varying of frequency of the incidence wave are obtained by numerical calculating. The numerical results show that the influence of the fractal dimension, the permittivity of substrate medium, the permittivity and the mean layer thickness of intermediate medium, the rms and the correlation length of the rough surface, and the incident frequency on the transmission coefficient is very complex.
2009, 31(1): 238-241.
doi: 10.3724/SP.J.1146.2007.01007
Abstract:
Due to high integration and high speed operation, array multiplier much likely suffers from delay fault. In this paper, a Built-In Self-Test (BIST) scheme is presented for the delay fault test of such array multiplier in which an accumulator is utilized as test pattern generator. Based on the transition propagation analysis of the basic unit of full adder, a kind of single input change BIST sequences is generated which has been designated to be more effective than multiple input change sequences when highly robust delay fault coverage is targeted in a series of previous theoretical and experimental results. The proposed scheme is well balanced between the path coverage and the number of test patterns. Simulation results demonstrate the proposed scheme can get high path coverage. Furthermore, the reuse of existing accumulator to generate test patterns can lead to low hardware overhead.
Due to high integration and high speed operation, array multiplier much likely suffers from delay fault. In this paper, a Built-In Self-Test (BIST) scheme is presented for the delay fault test of such array multiplier in which an accumulator is utilized as test pattern generator. Based on the transition propagation analysis of the basic unit of full adder, a kind of single input change BIST sequences is generated which has been designated to be more effective than multiple input change sequences when highly robust delay fault coverage is targeted in a series of previous theoretical and experimental results. The proposed scheme is well balanced between the path coverage and the number of test patterns. Simulation results demonstrate the proposed scheme can get high path coverage. Furthermore, the reuse of existing accumulator to generate test patterns can lead to low hardware overhead.
2009, 31(1): 242-245.
doi: 10.3724/SP.J.1146.2007.01156
Abstract:
Coupling capacitance and mutual inductance are important factors of crosstalk losses in high frequency. ABCD models with improper mutual inductance description have been reported to be used to obtain step response of coupling interconnects . In this paper, a more accurate ABCD model with modified mutual inductance is introduced. Finally, crosstalk coupling noise of interconnects in LTCC technology is analyzed using ADS simulation to verify the improved ABCD model.
Coupling capacitance and mutual inductance are important factors of crosstalk losses in high frequency. ABCD models with improper mutual inductance description have been reported to be used to obtain step response of coupling interconnects . In this paper, a more accurate ABCD model with modified mutual inductance is introduced. Finally, crosstalk coupling noise of interconnects in LTCC technology is analyzed using ADS simulation to verify the improved ABCD model.
2009, 31(1): 250-252.
doi: 10.3724/SP.J.1146.2007.01374
Abstract:
The characteristics of electromagnetic pulse produced by Photo-Conductive switches and Blumlein line under the bias voltage is studied by FDTD. The DAlemberts formula is used to analyze the principle of Blumlein line. A total reflection border and the source method are given for the situation that Blumlein line worked under bias voltage. The SIBC is used to model the PCSs. The propagation of pulse is computed. The waveform of different time is given. The experiment result agrees with the numerical result well. The relation between geometry and output voltage of Blumlein line is studied.
The characteristics of electromagnetic pulse produced by Photo-Conductive switches and Blumlein line under the bias voltage is studied by FDTD. The DAlemberts formula is used to analyze the principle of Blumlein line. A total reflection border and the source method are given for the situation that Blumlein line worked under bias voltage. The SIBC is used to model the PCSs. The propagation of pulse is computed. The waveform of different time is given. The experiment result agrees with the numerical result well. The relation between geometry and output voltage of Blumlein line is studied.
2009, 31(1): 246-249.
doi: 10.3724/SP.J.1146.2007.01234
Abstract:
Two kinds of forgery attacks strategy on the group signature schemes proposed respectively by Wang et al.. (2003) and Lin et al.. (2006) based on the Tseng-Jans(1999) group signature scheme is developed. Without using any secret identification or secret key, anyone can forgery a valid group member certificate and then generate a valid group signature using the forged certificate only through selecting some random parameters and changing the calculation procedures. Moreover, this kind of forgery attacks strategy can be used in Lee-Changs (1998) group signature scheme, Tseng-Jans group signature scheme and their varietals. It means this series of group signature schemes is insecure.
Two kinds of forgery attacks strategy on the group signature schemes proposed respectively by Wang et al.. (2003) and Lin et al.. (2006) based on the Tseng-Jans(1999) group signature scheme is developed. Without using any secret identification or secret key, anyone can forgery a valid group member certificate and then generate a valid group signature using the forged certificate only through selecting some random parameters and changing the calculation procedures. Moreover, this kind of forgery attacks strategy can be used in Lee-Changs (1998) group signature scheme, Tseng-Jans group signature scheme and their varietals. It means this series of group signature schemes is insecure.
