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2012 Vol. 34, No. 12
Display Method:
2012, 34(12): 2795-2801.
doi: 10.3724/SP.J.1146.2012.00863
Abstract:
In order to achieve sparse representation and capture more geometrical features of visual measuring image, a predicted method of edge information based on gray gradient direction is proposed first. Due to the precise positioning of edge, the method of combination of Lifting Wavelet Packet (LWP) transformation and general wavelet packet transformation is adopted to decompose the whole measuring image. Then the designed cost function maintained the integrity of edge information efficiently, that is the sum of energy mean of every sub-band and direction information. Finally, parent-child conflict of wavelet packet transformation in Set Partitioning In Hierarchical Trees (SPIHT) encoding is completed and resolved. By the test of distant view image, nearby view image, partial enlarged image and target image, the compression method for visual measuring image based on edge-directed LWP transformation SPHT encoding (LWP-SPIHT), preserved edge information of visual measuring image and enhanced the reconstructed quality and precision.
In order to achieve sparse representation and capture more geometrical features of visual measuring image, a predicted method of edge information based on gray gradient direction is proposed first. Due to the precise positioning of edge, the method of combination of Lifting Wavelet Packet (LWP) transformation and general wavelet packet transformation is adopted to decompose the whole measuring image. Then the designed cost function maintained the integrity of edge information efficiently, that is the sum of energy mean of every sub-band and direction information. Finally, parent-child conflict of wavelet packet transformation in Set Partitioning In Hierarchical Trees (SPIHT) encoding is completed and resolved. By the test of distant view image, nearby view image, partial enlarged image and target image, the compression method for visual measuring image based on edge-directed LWP transformation SPHT encoding (LWP-SPIHT), preserved edge information of visual measuring image and enhanced the reconstructed quality and precision.
2012, 34(12): 2802-2808.
doi: 10.3724/SP.J.1146.2012.00450
Abstract:
A new efficient technique using the compatible hardware framework to realize the integer 5/3 wavelet transform and 9/7 wavelet transform is proposed. The bit depth of the temp coefficients in the wavelet transform is based on the Bounded Input Bounded Output (BIBO) plus value of 9/7 wavelet transform, at the same time, the quantization value of 9/7 wavelet transform and how to do quantization is decided by BIBO puls value of 5/3 wavelet transform. Finally, both the coefficients of 5/3 wavelet transform and 9/7 wavelet transform are saved in the same memories. The proposed technique not only saves the hardware memory resource and computational complexity of the wavelet transform module, but also saves the hardware memory resource and computational complexity of the bitplane arithmetric coding based on the context module and post-compression rate-distortion optimization module.
A new efficient technique using the compatible hardware framework to realize the integer 5/3 wavelet transform and 9/7 wavelet transform is proposed. The bit depth of the temp coefficients in the wavelet transform is based on the Bounded Input Bounded Output (BIBO) plus value of 9/7 wavelet transform, at the same time, the quantization value of 9/7 wavelet transform and how to do quantization is decided by BIBO puls value of 5/3 wavelet transform. Finally, both the coefficients of 5/3 wavelet transform and 9/7 wavelet transform are saved in the same memories. The proposed technique not only saves the hardware memory resource and computational complexity of the wavelet transform module, but also saves the hardware memory resource and computational complexity of the bitplane arithmetric coding based on the context module and post-compression rate-distortion optimization module.
2012, 34(12): 2809-2815.
doi: 10.3724/SP.J.1146.2012.00727
Abstract:
Traditional video error concealment techniques perform poorly in handling loss MacroBlocks(MBs) with intense or complicated motion. Based on the statistic analysis of stereoscopic video coding prediction mode, this paper classifies the loss MBs into different categories according to the motion and disparity information of their neighboring correctly received or concealed MBs, and uses different methods to conceal different kinds of MBs. Therefor the recovery of loss MBs is more purposeful and efficient. Simulation results show that the proposed method can improve the concealment quality of intense or complicated motion region.
Traditional video error concealment techniques perform poorly in handling loss MacroBlocks(MBs) with intense or complicated motion. Based on the statistic analysis of stereoscopic video coding prediction mode, this paper classifies the loss MBs into different categories according to the motion and disparity information of their neighboring correctly received or concealed MBs, and uses different methods to conceal different kinds of MBs. Therefor the recovery of loss MBs is more purposeful and efficient. Simulation results show that the proposed method can improve the concealment quality of intense or complicated motion region.
2012, 34(12): 2816-2822.
doi: 10.3724/SP.J.1146.2012.00583
Abstract:
Interference is one of the key performance metrics in the design of cellular networks; Interference Alignment (IA) can eliminate the impact of interference and improve the capacity performance of cellular networks. In classic IA algorithms for downlink cellular networks, users improve the performance from their own point of view, so limit the sum capacity of cells. A new IA technique for downlink cellular networks is proposed in view of improving the sum capacity performance of per cell. Downlink IA mathematics model for cellular networks is constructed, receive vector is chosen to maximize SINR at the receivers, and precoder matrix is created by gradient projection method to maximize the sum capacity of per cell at base-stations. Numerical results show that the new algorithm has better capacity performance than classic downlink IA algorithms for cellular networks.
Interference is one of the key performance metrics in the design of cellular networks; Interference Alignment (IA) can eliminate the impact of interference and improve the capacity performance of cellular networks. In classic IA algorithms for downlink cellular networks, users improve the performance from their own point of view, so limit the sum capacity of cells. A new IA technique for downlink cellular networks is proposed in view of improving the sum capacity performance of per cell. Downlink IA mathematics model for cellular networks is constructed, receive vector is chosen to maximize SINR at the receivers, and precoder matrix is created by gradient projection method to maximize the sum capacity of per cell at base-stations. Numerical results show that the new algorithm has better capacity performance than classic downlink IA algorithms for cellular networks.
2012, 34(12): 2823-2829.
doi: 10.3724/SP.J.1146.2012.00744
Abstract:
In Long Term Evolution (LTE) heterogeneous networks, the gap between the power of Macro base station and Pico base station makes some users access to Macrocell even if they are closer to Picocell. Under this circumstance, Picocell may suffer severe uplink interference which could not be accurately identified under current schemes. Range Expansion (RE) could mitigate the uplink interference problem. However, it may bring new downlink interference at the same time. This paper proposes an Uplink Interference Identification and Coordination scheme based on Range Expansion (UIICRE) with theoretical analysis. UIICRE could identify the uplink interference sources and their interference strength, and then coordinate the interference according to the identification results. Simulation results show that UIICRE could promote UEs uplink SINR under the condition that its downlink SINR would not be severely affected.
In Long Term Evolution (LTE) heterogeneous networks, the gap between the power of Macro base station and Pico base station makes some users access to Macrocell even if they are closer to Picocell. Under this circumstance, Picocell may suffer severe uplink interference which could not be accurately identified under current schemes. Range Expansion (RE) could mitigate the uplink interference problem. However, it may bring new downlink interference at the same time. This paper proposes an Uplink Interference Identification and Coordination scheme based on Range Expansion (UIICRE) with theoretical analysis. UIICRE could identify the uplink interference sources and their interference strength, and then coordinate the interference according to the identification results. Simulation results show that UIICRE could promote UEs uplink SINR under the condition that its downlink SINR would not be severely affected.
Research on Power Allocation Scheme Based on Water-filling Algorithm in Cooperative Diversity System
2012, 34(12): 2830-2836.
doi: 10.3724/SP.J.1146.2012.00682
Abstract:
In order to increase the capacity of cooperative diversity system, a novel power allocation scheme based on water-filling algorithm is proposed under the background of multiple-relay cooperation. First, a novel node index mapping scheme is provided to enhance the orthogonality of signal transmitted by relay nodes. For the GABBA codes applying linear orthogonal decoding, the proposed scheme can decrease the symbol error rate. Then, by analyzing the relationship between SNR and the power allocated by relay nodes, a two-step solution with water-filling algorithm is proposed to solve the optimization problem. Simulation results indicate that, the scheme based on water-filling algorithm can obtain better performance on SER compared with equal allocation scheme. In addition, both the two schemes can obtain the same diversity order NtNr, which is same as MIMO scenario. Furthermore, this scheme can achieve higher capacity for different antenna-deployment. The capacity of cooperative diversity system is proportional to min{NtNr}log2M.
In order to increase the capacity of cooperative diversity system, a novel power allocation scheme based on water-filling algorithm is proposed under the background of multiple-relay cooperation. First, a novel node index mapping scheme is provided to enhance the orthogonality of signal transmitted by relay nodes. For the GABBA codes applying linear orthogonal decoding, the proposed scheme can decrease the symbol error rate. Then, by analyzing the relationship between SNR and the power allocated by relay nodes, a two-step solution with water-filling algorithm is proposed to solve the optimization problem. Simulation results indicate that, the scheme based on water-filling algorithm can obtain better performance on SER compared with equal allocation scheme. In addition, both the two schemes can obtain the same diversity order NtNr, which is same as MIMO scenario. Furthermore, this scheme can achieve higher capacity for different antenna-deployment. The capacity of cooperative diversity system is proportional to min{NtNr}log2M.
2012, 34(12): 2837-2842.
doi: 10.3724/SP.J.1146.2012.00434
Abstract:
Based on the property that the equivalent binary block codes of Reed-Solomon (RS) codes are quasi- cyclic codes, a new blind recognition method of RS codes is proposed. The intercepted binary sequence is regarded as linear codes over a ring. Then, the decomposition into component codes of equivalent codes is conducted by using the Chinese Reminder Theorem (CRT). By computing the normalized dimensions of the component codes over different fields and finding the minimum of them, the length and the primitive polynomial of the RS code are estimated. Finally the generator polynomial can be obtained by factoring the RS code words. The proposed method has lower computational complexity and uses less intercepted data than existing methods. Simulation results show that it has good performance even if with high BER situation.
Based on the property that the equivalent binary block codes of Reed-Solomon (RS) codes are quasi- cyclic codes, a new blind recognition method of RS codes is proposed. The intercepted binary sequence is regarded as linear codes over a ring. Then, the decomposition into component codes of equivalent codes is conducted by using the Chinese Reminder Theorem (CRT). By computing the normalized dimensions of the component codes over different fields and finding the minimum of them, the length and the primitive polynomial of the RS code are estimated. Finally the generator polynomial can be obtained by factoring the RS code words. The proposed method has lower computational complexity and uses less intercepted data than existing methods. Simulation results show that it has good performance even if with high BER situation.
2012, 34(12): 2843-2849.
doi: 10.3724/SP.J.1146.2012.00326
Abstract:
The resource allocation issue in multi-services OFDMA systems is formulated by taking Quality of Service (QoS) requirement, data arrival process, system constraints into account. The relations among the traffic rate constraint, latency constraint and the queue length are analyzed. The original issue is decomposed into some independent sub-problems by dual decomposition scheme. The optimal resource blocks allocation scheme and optimal power allocation scheme can be obtained and a Dual Decomposition Based (DDB) optimization resource allocation algorithm is proposed. Simulation results show that total throughput maximum for non-real-time services is achieved by employing DDB algorithm with low service violation probability, nice fairness and slightly increased algorithm complexity.
The resource allocation issue in multi-services OFDMA systems is formulated by taking Quality of Service (QoS) requirement, data arrival process, system constraints into account. The relations among the traffic rate constraint, latency constraint and the queue length are analyzed. The original issue is decomposed into some independent sub-problems by dual decomposition scheme. The optimal resource blocks allocation scheme and optimal power allocation scheme can be obtained and a Dual Decomposition Based (DDB) optimization resource allocation algorithm is proposed. Simulation results show that total throughput maximum for non-real-time services is achieved by employing DDB algorithm with low service violation probability, nice fairness and slightly increased algorithm complexity.
2012, 34(12): 2850-2854.
doi: 10.3724/SP.J.1146.2012.00670
Abstract:
In multiple-input multiple-output interference channels, Interference alignment suffers from performance loss at low Signal-to-Noise Ratio (SNR) due to it neglecting the desired signal power. An algorithm is proposed that iteratively minimizes weighted sum of leakages caused by both interference and desired signal out of their corresponding subspace. The weighted factors are allowed to be adjusted according to SNR. Simulation result shows that the proposed algorithm can improve sum rate effectively at low SNR.
In multiple-input multiple-output interference channels, Interference alignment suffers from performance loss at low Signal-to-Noise Ratio (SNR) due to it neglecting the desired signal power. An algorithm is proposed that iteratively minimizes weighted sum of leakages caused by both interference and desired signal out of their corresponding subspace. The weighted factors are allowed to be adjusted according to SNR. Simulation result shows that the proposed algorithm can improve sum rate effectively at low SNR.
2012, 34(12): 2855-2861.
doi: 10.3724/SP.J.1146.2012.00619
Abstract:
High data rate communication over limited bandwidth or multi-path channels suffers severe distortion due to the Inter-Symbol Interference (ISI). Constant Modulus blind equalization Algorithms (CMA) are widely used for mitigating this phenomenon. But for higher-order no constant amplitude modulations, CMA works less effective for its large residual error. A simple modified error function which is suitable for variable constellation is proposed for better convergence performance. The new algorithm is well verified by theoretic analysis and numerical simulations, and the theoretic analysis and simulations show that the new algorithms residual error is much less than the origin algorithms in MQAM and MAPSK modulation systems and the new algorithm is suitable for applications under these conditions.
High data rate communication over limited bandwidth or multi-path channels suffers severe distortion due to the Inter-Symbol Interference (ISI). Constant Modulus blind equalization Algorithms (CMA) are widely used for mitigating this phenomenon. But for higher-order no constant amplitude modulations, CMA works less effective for its large residual error. A simple modified error function which is suitable for variable constellation is proposed for better convergence performance. The new algorithm is well verified by theoretic analysis and numerical simulations, and the theoretic analysis and simulations show that the new algorithms residual error is much less than the origin algorithms in MQAM and MAPSK modulation systems and the new algorithm is suitable for applications under these conditions.
2012, 34(12): 2862-2868.
doi: 10.3724/SP.J.1146.2012.00816
Abstract:
The multipath effects of the HF channel make the BER of non-sinusodial HF communication based on Prolate Spheroidal Wave Function (PSWF) increasing. An new equalizer scheme is proposed on the base of analysising the factors reducing the quality of decision dates and the particularity of the non-sinusodial communication systerm based on PSWF. This scheme transfer the effects of ISI to the quality of the decision date signals，and taking measures to equilibrium each path of decision date signals to improve its quality. Finally, the disicion will be made according to the judgement criterion. The results of the simulations show that the new equalizer is effective, and the BER can be reducing from 10-2 to 10-3, when the SNR is 24 dB. For the group of different characteristics of PSWF pulses which come from different pulse generating methods including constructing method of PSWF based on single-channel and constructing method of PSWF based on multi-channel, parameters shared equalizer and grouping parameters shared equalizer are put forwad. The results of the simulations show that: the two kinds of equalizers are effective.
The multipath effects of the HF channel make the BER of non-sinusodial HF communication based on Prolate Spheroidal Wave Function (PSWF) increasing. An new equalizer scheme is proposed on the base of analysising the factors reducing the quality of decision dates and the particularity of the non-sinusodial communication systerm based on PSWF. This scheme transfer the effects of ISI to the quality of the decision date signals，and taking measures to equilibrium each path of decision date signals to improve its quality. Finally, the disicion will be made according to the judgement criterion. The results of the simulations show that the new equalizer is effective, and the BER can be reducing from 10-2 to 10-3, when the SNR is 24 dB. For the group of different characteristics of PSWF pulses which come from different pulse generating methods including constructing method of PSWF based on single-channel and constructing method of PSWF based on multi-channel, parameters shared equalizer and grouping parameters shared equalizer are put forwad. The results of the simulations show that: the two kinds of equalizers are effective.
2012, 34(12): 2869-2875.
doi: 10.3724/SP.J.1146.2012.00633
Abstract:
To separate the Paired Carrier Multiple Access (PCMA) signals, a joint linear Minimum Mean-Square Error (MMSE) equalization and soft decoding iteration demodulation/decoding algorithm is proposed in this paper, which is based on the realization of the channel parameters estimation and the interference cancellation. In the course of equalization, the algorithm exploits the feedback prior statistics after decoding to improve the performance of demodulation, with special emphasis on the information interaction between equalization and decoding and the impact of the parameters estimation error on the performance of demodulation. Simulation results show that, with Turbo Product Codes (TPC) codes whose subcode is (64,57,4) expand BCH codes, a gain of about 4 dB in signal-noise ratio can be obtained after two iterations for QPSK signals at a bit error rate of 10-3; Moreover, the bit error rate can be promoted by at least two orders of magnitude after two iterations, when 8PSK modulationis exploited andEs/N0 is more than 20 dB.
To separate the Paired Carrier Multiple Access (PCMA) signals, a joint linear Minimum Mean-Square Error (MMSE) equalization and soft decoding iteration demodulation/decoding algorithm is proposed in this paper, which is based on the realization of the channel parameters estimation and the interference cancellation. In the course of equalization, the algorithm exploits the feedback prior statistics after decoding to improve the performance of demodulation, with special emphasis on the information interaction between equalization and decoding and the impact of the parameters estimation error on the performance of demodulation. Simulation results show that, with Turbo Product Codes (TPC) codes whose subcode is (64,57,4) expand BCH codes, a gain of about 4 dB in signal-noise ratio can be obtained after two iterations for QPSK signals at a bit error rate of 10-3; Moreover, the bit error rate can be promoted by at least two orders of magnitude after two iterations, when 8PSK modulationis exploited andEs/N0 is more than 20 dB.
2012, 34(12): 2876-2880.
doi: 10.3724/SP.J.1146.2012.00187
Abstract:
A construction of multiple Zero Correlation Zone (ZCZ) sequence sets is presented. The new ZCZ sequence set consists of several subsets, each subset is a ZCZ sequence set by itself and the cross-correlation function between sequences belonging to different subsets also has a zero-correlation zone. The sequence sets constructed are multiple ternary ZCZ sequence sets, these sequence sets have the same performance parameters but larger set size compared with that constructed by Hayashi.
A construction of multiple Zero Correlation Zone (ZCZ) sequence sets is presented. The new ZCZ sequence set consists of several subsets, each subset is a ZCZ sequence set by itself and the cross-correlation function between sequences belonging to different subsets also has a zero-correlation zone. The sequence sets constructed are multiple ternary ZCZ sequence sets, these sequence sets have the same performance parameters but larger set size compared with that constructed by Hayashi.
2012, 34(12): 2881-2884.
doi: 10.3724/SP.J.1146.2012.00804
Abstract:
The construction of the generalized cyclotomic sequence with lengthpn for a prime p and a positive integern given by Liu Fang et al. (2010) is generalized in this paper. The linear complexity and the autocorrelation values of the new defined sequences are also determined. The results show that the new defined sequences keep the pseudo-random properties of the original sequence, that is, the high linear complexity and undesirable autocorrelation properties. Owing to the flexible ways to assign values to different generalized cyclotomic classes, the new construction contains more classes of generalized cyclotomic sequences when it is compared with the original one.
The construction of the generalized cyclotomic sequence with lengthpn for a prime p and a positive integern given by Liu Fang et al. (2010) is generalized in this paper. The linear complexity and the autocorrelation values of the new defined sequences are also determined. The results show that the new defined sequences keep the pseudo-random properties of the original sequence, that is, the high linear complexity and undesirable autocorrelation properties. Owing to the flexible ways to assign values to different generalized cyclotomic classes, the new construction contains more classes of generalized cyclotomic sequences when it is compared with the original one.
2012, 34(12): 2885-2890.
doi: 10.3724/SP.J.1146.2012.00300
Abstract:
Considering the information loss during sharing multiple secrets, a definition of (n, n) lossless multi- secret sharing visual cryptography is proposed. In addition, based on ring shares, an (n, n) multi-secret visual cryptography scheme, which shares secret images with no information loss, is designed. The experimental results show that in this scheme, not only multiple participants can share multiple secret images, but also secret images can be reconstructed perfectly.
Considering the information loss during sharing multiple secrets, a definition of (n, n) lossless multi- secret sharing visual cryptography is proposed. In addition, based on ring shares, an (n, n) multi-secret visual cryptography scheme, which shares secret images with no information loss, is designed. The experimental results show that in this scheme, not only multiple participants can share multiple secret images, but also secret images can be reconstructed perfectly.
2012, 34(12): 2891-2897.
doi: 10.3724/SP.J.1146.2012.00730
Abstract:
An Efficient Asynchronous Probing Scheme (EAPS) is proposed to solve issues of the low discovery radio and high probing energy cost for Delay Tolerant Mobility Sensor Network (DTMSN). By analyzing nodes contact properties in the Random Way-Point (RWP) mobility model, EAPS gives a reasonable regional plan based on a slotted-wakeup schedule of coprime cycle pairs. Optimal coprime cycle pairs are selected in these different regions to improve the discovery radio and reduce energy cost. Comparing with past asynchronous probing schemes, simulation results show that EAPS has higher discovery ratio and lower discovery delay with a low energy cost.
An Efficient Asynchronous Probing Scheme (EAPS) is proposed to solve issues of the low discovery radio and high probing energy cost for Delay Tolerant Mobility Sensor Network (DTMSN). By analyzing nodes contact properties in the Random Way-Point (RWP) mobility model, EAPS gives a reasonable regional plan based on a slotted-wakeup schedule of coprime cycle pairs. Optimal coprime cycle pairs are selected in these different regions to improve the discovery radio and reduce energy cost. Comparing with past asynchronous probing schemes, simulation results show that EAPS has higher discovery ratio and lower discovery delay with a low energy cost.
2012, 34(12): 2898-2904.
doi: 10.3724/SP.J.1146.2012.00101
Abstract:
Virtual network service persistence will be impacted by substrate node or link failure, so how to achieve the reliable mapping of virtual network is recently an important problem to be solved. In this paper, a virtual network mapping problem is modeled, and then the reliability of virtual network is quantified and analyzed to sum up the main influence factors. To overcome these factors, an algorithm of Virtual Network Mapping based on Topology Impact Degree (VNM-TID) and a Migration Algorithm based on Backtracking (MA-Back) are separately proposed. Simulation results show that the algorithms have advantages on virtual network Request Accepted Ratio (RAR), Migration Success Ratio (MSR) and Valid Loading Ratio (VLR), and therefore improve the reliability of virtual network.
Virtual network service persistence will be impacted by substrate node or link failure, so how to achieve the reliable mapping of virtual network is recently an important problem to be solved. In this paper, a virtual network mapping problem is modeled, and then the reliability of virtual network is quantified and analyzed to sum up the main influence factors. To overcome these factors, an algorithm of Virtual Network Mapping based on Topology Impact Degree (VNM-TID) and a Migration Algorithm based on Backtracking (MA-Back) are separately proposed. Simulation results show that the algorithms have advantages on virtual network Request Accepted Ratio (RAR), Migration Success Ratio (MSR) and Valid Loading Ratio (VLR), and therefore improve the reliability of virtual network.
2012, 34(12): 2905-2912.
doi: 10.3724/SP.J.1146.2012.00924
Abstract:
In order to reduce the probe cost and improve the accuracy of the inference algorithm of the link loss rate, a novel link loss rate inference algorithm is proposed based on minimal cover set. This algorithm reduces the number of the end-to-end paths by reducing the rank of the routing matrix that caused by the minimal cover set measurements. On the other hand, the accuracy of the algorithm is improved by the implement of the solving linear equations and Gibbs sample. Simulation results show that this algorithm can obtain a higher accuracy with less end-to-end measurement paths.
In order to reduce the probe cost and improve the accuracy of the inference algorithm of the link loss rate, a novel link loss rate inference algorithm is proposed based on minimal cover set. This algorithm reduces the number of the end-to-end paths by reducing the rank of the routing matrix that caused by the minimal cover set measurements. On the other hand, the accuracy of the algorithm is improved by the implement of the solving linear equations and Gibbs sample. Simulation results show that this algorithm can obtain a higher accuracy with less end-to-end measurement paths.
2012, 34(12): 2913-2919.
doi: 10.3724/SP.J.1146.2012.00562
Abstract:
Multi-channel SAR in azimuth, which can be used to suppress the Doppler ambiguity to get the High-Resolution Wide-Swath (HRWS) SAR images, suffers from the amplitude and phase mismatch among the channels, as well as the position measurement inaccuracy of the antenna phase centers. Based on the analysis of the phase error characteristics of the multi-channel SAR, this paper presents a novel data-based phase error estimation method in time-domain. Firstly, the echoes in time-domain received by the adjacent channels are processed to get interferometric phases, which consist of the Doppler centroid information and the difference of the phase biases between the adjacent channels. The Doppler centroid can be extracted by circular integral of the adjacent interferometric phases. Finally, the phase bias between each channel and the reference one can be obtained by integral of the interferometric phase subtracted by the phase of the Doppler centroid. Using the presented method, both the phase bias and the Doppler centroid of the raw echoes can be effectively estimated. The performance of presented method is validated by the experiments of simulated spaceborne multi-channel SAR data.
Multi-channel SAR in azimuth, which can be used to suppress the Doppler ambiguity to get the High-Resolution Wide-Swath (HRWS) SAR images, suffers from the amplitude and phase mismatch among the channels, as well as the position measurement inaccuracy of the antenna phase centers. Based on the analysis of the phase error characteristics of the multi-channel SAR, this paper presents a novel data-based phase error estimation method in time-domain. Firstly, the echoes in time-domain received by the adjacent channels are processed to get interferometric phases, which consist of the Doppler centroid information and the difference of the phase biases between the adjacent channels. The Doppler centroid can be extracted by circular integral of the adjacent interferometric phases. Finally, the phase bias between each channel and the reference one can be obtained by integral of the interferometric phase subtracted by the phase of the Doppler centroid. Using the presented method, both the phase bias and the Doppler centroid of the raw echoes can be effectively estimated. The performance of presented method is validated by the experiments of simulated spaceborne multi-channel SAR data.
2012, 34(12): 2920-2926.
doi: 10.3724/SP.J.1146.2012.00496
Abstract:
It is valuable to extract multi-aspect SAR feature for radar object recognition. The Gapped-data Amplitude and Phase EStimation (GAPES) are modified to extract multi-aspect SAR feature. Multi-aspect SAR Feature Extraction is a parameter estimation issue with gapped-data case. This algorithm does not need the parametric model of object. In addition, there is no need to fulfill the gapped data and it avoids the error induced by the interpolation. The new approach is not only able to improve the estimative precision of location and amplitude, but also to improve the resolution. Numerical experiments are provided to demonstrate the performance of the algorithm and to show the advantages of multi-aspect SAR data to reconstruct object.
It is valuable to extract multi-aspect SAR feature for radar object recognition. The Gapped-data Amplitude and Phase EStimation (GAPES) are modified to extract multi-aspect SAR feature. Multi-aspect SAR Feature Extraction is a parameter estimation issue with gapped-data case. This algorithm does not need the parametric model of object. In addition, there is no need to fulfill the gapped data and it avoids the error induced by the interpolation. The new approach is not only able to improve the estimative precision of location and amplitude, but also to improve the resolution. Numerical experiments are provided to demonstrate the performance of the algorithm and to show the advantages of multi-aspect SAR data to reconstruct object.
2012, 34(12): 2927-2933.
doi: 10.3724/SP.J.1146.2012.00655
Abstract:
In the ISAR imaging of targets with rotating parts, the image of the targets main body may be shadowed by the micro-Doppler effect induced by the rotating parts. To solve this problem, an algorithm utilizing complex local mean decomposition is researched to separate the micro-Doppler signature. The Doppler frequency difference between the main body and the rotating parts is analyzed, and the complex local mean decomposition method is utilized to separate the micro-Doppler signature which accurately separate the oscillation mode embedded in signals and decompose the complex modulation non-stationary signals adaptively into some stable mono-components. After the separation, better geometrical features of the main body and micro-Doppler features of the rotating parts can be obtained by processing each independently. The results from the simulated and measured data are given to verify the validity of the proposed algorithm.
In the ISAR imaging of targets with rotating parts, the image of the targets main body may be shadowed by the micro-Doppler effect induced by the rotating parts. To solve this problem, an algorithm utilizing complex local mean decomposition is researched to separate the micro-Doppler signature. The Doppler frequency difference between the main body and the rotating parts is analyzed, and the complex local mean decomposition method is utilized to separate the micro-Doppler signature which accurately separate the oscillation mode embedded in signals and decompose the complex modulation non-stationary signals adaptively into some stable mono-components. After the separation, better geometrical features of the main body and micro-Doppler features of the rotating parts can be obtained by processing each independently. The results from the simulated and measured data are given to verify the validity of the proposed algorithm.
2012, 34(12): 2934-2941.
doi: 10.3724/SP.J.1146.2012.00720
Abstract:
In ultra-wideband radar imaging applications, there exist non-orthogonal sidelobes which would affect the image. The relationship between point spread function and spatial spectrum supporting region is analyzed in this paper. To improve the image quality, an approach based on virtual sub-aperture radar images is proposed to reduce the non-orthogonal sidelobes. This approach separates the mainlobe from the sidelobes, which suppresses the sidelobes and keeps the mainlobe simultaneously. The simulation results show significant reduction of the sidelobe level.
In ultra-wideband radar imaging applications, there exist non-orthogonal sidelobes which would affect the image. The relationship between point spread function and spatial spectrum supporting region is analyzed in this paper. To improve the image quality, an approach based on virtual sub-aperture radar images is proposed to reduce the non-orthogonal sidelobes. This approach separates the mainlobe from the sidelobes, which suppresses the sidelobes and keeps the mainlobe simultaneously. The simulation results show significant reduction of the sidelobe level.
2012, 34(12): 2942-2947.
doi: 10.3724/SP.J.1146.2012.00718
Abstract:
A novel joint 4-Dimensional (4-D) angle and Doppler frequency estimation algorithm is proposed for bistatic MIMO radar with L-shaped arrays. The DOA matrix method is used to construct the date model and then the close-form solution of the two dimensional DOA, the two dimensional DOD and Doppler frequency can be obtained. The proposed algorithm requires no searching spectral peak, and the estimated five dimensional parameters of the targets can be paired automatically. The proposed algorithm has very close parameters estimation to ESPRIT algorithm which has a much higher complexity than the algorithm. The method can eliminate the effect of the spatial colored noise and it is applicable even if the transmitted waveforms are not entirely orthogonal. The simulation results verify its effectiveness.
A novel joint 4-Dimensional (4-D) angle and Doppler frequency estimation algorithm is proposed for bistatic MIMO radar with L-shaped arrays. The DOA matrix method is used to construct the date model and then the close-form solution of the two dimensional DOA, the two dimensional DOD and Doppler frequency can be obtained. The proposed algorithm requires no searching spectral peak, and the estimated five dimensional parameters of the targets can be paired automatically. The proposed algorithm has very close parameters estimation to ESPRIT algorithm which has a much higher complexity than the algorithm. The method can eliminate the effect of the spatial colored noise and it is applicable even if the transmitted waveforms are not entirely orthogonal. The simulation results verify its effectiveness.
2012, 34(12): 2948-2953.
doi: 10.3724/SP.J.1146.2012.00642
Abstract:
Both the spatial property and the temporal property should be considered in MIMO radar waveform design. It is a challenge to reduce the temporal sidelobe efficiently by designing the waveform in a single pulse, when the spatial property should be guaranteed. In this paper, an approach of pulse train code is proposed to suppress the temporal sidelobe, by which the spatial beampattern design and the temporal waveform design can be separated. The temporal sidelobe can be reduced without changing the beampattern. The numerical results show that the proposed method can reduce the range sidelobe in each Doppler channel efficiently with the consideration of Doppler frequency shift.
Both the spatial property and the temporal property should be considered in MIMO radar waveform design. It is a challenge to reduce the temporal sidelobe efficiently by designing the waveform in a single pulse, when the spatial property should be guaranteed. In this paper, an approach of pulse train code is proposed to suppress the temporal sidelobe, by which the spatial beampattern design and the temporal waveform design can be separated. The temporal sidelobe can be reduced without changing the beampattern. The numerical results show that the proposed method can reduce the range sidelobe in each Doppler channel efficiently with the consideration of Doppler frequency shift.
2012, 34(12): 2954-2958.
doi: 10.3724/SP.J.1146.2012.00717
Abstract:
To deal with low sidelobe transmit pattern design problem for MIMO radar, a new minimum peak-sidelobe or integrated-sidelobe transmit pattern optimization algorithm is proposed in this paper. Due to the optimization problem of minimizing peak-sidelobe or integrated-sidelobe is non-convex, it is solved in two steps by the proposed algorithm. A convex problem is solved in the first step, and in the second step, the global optimum of original problem is attained by scale transformation of the solution in the first step. The simulations show that the transmit pattern have lower peak-sidelobe or integrated-sidelobe with this algorithm than existed algorithm.
To deal with low sidelobe transmit pattern design problem for MIMO radar, a new minimum peak-sidelobe or integrated-sidelobe transmit pattern optimization algorithm is proposed in this paper. Due to the optimization problem of minimizing peak-sidelobe or integrated-sidelobe is non-convex, it is solved in two steps by the proposed algorithm. A convex problem is solved in the first step, and in the second step, the global optimum of original problem is attained by scale transformation of the solution in the first step. The simulations show that the transmit pattern have lower peak-sidelobe or integrated-sidelobe with this algorithm than existed algorithm.
2012, 34(12): 2959-2965.
doi: 10.3724/SP.J.1146.2012.00122
Abstract:
There exist bound gravity-capillary waves that move at the speed of the dominate waves on the ocean surface, apart from free gravity-capillary waves that satisfy the linear dispersion relation. Based on the Bound\Free wave composite surface model (BF), a theoretical model to predict the Doppler bandwidths of bound and free waves is proposed in this paper. The numerical simulations and microwave experiments in the wind-wave tank are shown in this paper, to discuss their Doppler characteristics of bound and free waves under different wind speeds and radar frequencies.
There exist bound gravity-capillary waves that move at the speed of the dominate waves on the ocean surface, apart from free gravity-capillary waves that satisfy the linear dispersion relation. Based on the Bound\Free wave composite surface model (BF), a theoretical model to predict the Doppler bandwidths of bound and free waves is proposed in this paper. The numerical simulations and microwave experiments in the wind-wave tank are shown in this paper, to discuss their Doppler characteristics of bound and free waves under different wind speeds and radar frequencies.
2012, 34(12): 2966-2971.
doi: 10.3724/SP.J.1146.2012.00437
Abstract:
The issue of angle estimation in Multiple-Input Multiple-Output (MIMO) radar is discussed without knowledge of waveforms correlated matrix, and an improved MUltiple SIgnal Classification (MUSIC) algorithm is proposed for Direction Of Arrival (DOA) estimation in monostatic MIMO radar. The proposed algorithm does not require the knowledge of transmit waveforms correlated matrix, and has better angle estimation performance than the conventional Propagator Method (PM), Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm, and MUSIC based on reconstruction of output signal. And the algorithm can be used in MIMO radar with any array construction for angle estimation, and the Cramr-Rao Bound (CRB) in monostatic MIMO radar is derived. The simulation results demonstrate the effectiveness of the proposed approach.
The issue of angle estimation in Multiple-Input Multiple-Output (MIMO) radar is discussed without knowledge of waveforms correlated matrix, and an improved MUltiple SIgnal Classification (MUSIC) algorithm is proposed for Direction Of Arrival (DOA) estimation in monostatic MIMO radar. The proposed algorithm does not require the knowledge of transmit waveforms correlated matrix, and has better angle estimation performance than the conventional Propagator Method (PM), Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm, and MUSIC based on reconstruction of output signal. And the algorithm can be used in MIMO radar with any array construction for angle estimation, and the Cramr-Rao Bound (CRB) in monostatic MIMO radar is derived. The simulation results demonstrate the effectiveness of the proposed approach.
2012, 34(12): 2972-2977.
doi: 10.3724/SP.J.1146.2012.00656
Abstract:
Based on the equivalent scatter center model, the relationship between the micro-Doppler frequencies and the motion parameters of the space cone target with precession or nutation is analyzed. Due to the complicated form of the micro-Doppler frequency mentioned above, an approach to separate the micro-Doppler frequency curve of each equivalent scatter center in the Time Frequency Distribution (TFD) of target echo is proposed in this paper. In this method, classical Short-Time Fourier Transformer (STFT) is first used to obtain the TFD of the target echo; then the Multiple Target Tracking (MTT) algorithm is applied to track the micro-Doppler frequency curves in the TFD, which are assumed to be the tracks of maneuvering targets. Thus the micro-Doppler frequencies of each equivalent scatter center are extracted via the method. In the simulation experiments, the performance of the proposed method is evaluated via the electromagnetic computation simulated data.
Based on the equivalent scatter center model, the relationship between the micro-Doppler frequencies and the motion parameters of the space cone target with precession or nutation is analyzed. Due to the complicated form of the micro-Doppler frequency mentioned above, an approach to separate the micro-Doppler frequency curve of each equivalent scatter center in the Time Frequency Distribution (TFD) of target echo is proposed in this paper. In this method, classical Short-Time Fourier Transformer (STFT) is first used to obtain the TFD of the target echo; then the Multiple Target Tracking (MTT) algorithm is applied to track the micro-Doppler frequency curves in the TFD, which are assumed to be the tracks of maneuvering targets. Thus the micro-Doppler frequencies of each equivalent scatter center are extracted via the method. In the simulation experiments, the performance of the proposed method is evaluated via the electromagnetic computation simulated data.
2012, 34(12): 2978-2984.
doi: 10.3724/SP.J.1146.2012.00766
Abstract:
An interference suppression method based on joint fractional Fourier domain and time domain is proposed in this paper, to solve the problem of co-channel interference caused by homo-type radars working in ship formation. The interferences with different chirp rate from echo signal can be eliminated at fractional Fourier domain, and because of the reversibility of fractional Fourier transform, the ones with similar chirp rate can be cancelled by against-asynchronism of adjacent periods at time domain. Computer simulation results show that interference suppression processing gain reaches 29 dB. This method presents technical support for the ElectroMagnetic Compatibility (EMC) research in the ship formation.
An interference suppression method based on joint fractional Fourier domain and time domain is proposed in this paper, to solve the problem of co-channel interference caused by homo-type radars working in ship formation. The interferences with different chirp rate from echo signal can be eliminated at fractional Fourier domain, and because of the reversibility of fractional Fourier transform, the ones with similar chirp rate can be cancelled by against-asynchronism of adjacent periods at time domain. Computer simulation results show that interference suppression processing gain reaches 29 dB. This method presents technical support for the ElectroMagnetic Compatibility (EMC) research in the ship formation.
2012, 34(12): 2985-2991.
doi: 10.3724/SP.J.1146.2012.00615
Abstract:
Traditional object extraction methods encounter new challenges as the spatial resolution of remote sensing image increases. For the purpose of building extraction in that circumstance, a new method combining both attribute filtering and context analysis is proposed in this paper. Firstly, attribute filters are performed on the object level, which is defined by the connected pixels with similar attribute. Secondly, according to the prior knowledge of buildings and shadows, preliminary regions are extracted as the building candidates. Thirdly, the context between building and shadow is considered, which leads to the aspect angle, relative position and central distance criteria for the confirmation of buildings from the building candidates. Results on both of the residential and industrial regions demonstrate that the proposed method is effective for building extraction and performs better than the traditional methods.
Traditional object extraction methods encounter new challenges as the spatial resolution of remote sensing image increases. For the purpose of building extraction in that circumstance, a new method combining both attribute filtering and context analysis is proposed in this paper. Firstly, attribute filters are performed on the object level, which is defined by the connected pixels with similar attribute. Secondly, according to the prior knowledge of buildings and shadows, preliminary regions are extracted as the building candidates. Thirdly, the context between building and shadow is considered, which leads to the aspect angle, relative position and central distance criteria for the confirmation of buildings from the building candidates. Results on both of the residential and industrial regions demonstrate that the proposed method is effective for building extraction and performs better than the traditional methods.
2012, 34(12): 2992-2998.
doi: 10.3724/SP.J.1146.2012.00750
Abstract:
The information of targets scale is an important factor for small target detection in two-dimensional image. This paper presents a small target detection method based on second order directional derivative scale-space, chooses directly the interest target with the information of targets scale. On the basis of Lindebergs scale-space theory, the maximum and minimum second order directional derivative scale-spaces are derived, with the method of partial differential equations, and the characteristics of targets scale in the scale-spaces are analyzed. Meantime, the selection of parameters for constructing scale-spaces is given. On the analysis of the response of different targets in the scale-spaces, the implement algorithm using the second order directional derivative scale-space to detect small target is proposed. Experiments on the actual image show that the proposed method has a more robust detection performance than the compared one, and the detection capability of Laplace scale-space for non-circular structure target is improved.
The information of targets scale is an important factor for small target detection in two-dimensional image. This paper presents a small target detection method based on second order directional derivative scale-space, chooses directly the interest target with the information of targets scale. On the basis of Lindebergs scale-space theory, the maximum and minimum second order directional derivative scale-spaces are derived, with the method of partial differential equations, and the characteristics of targets scale in the scale-spaces are analyzed. Meantime, the selection of parameters for constructing scale-spaces is given. On the analysis of the response of different targets in the scale-spaces, the implement algorithm using the second order directional derivative scale-space to detect small target is proposed. Experiments on the actual image show that the proposed method has a more robust detection performance than the compared one, and the detection capability of Laplace scale-space for non-circular structure target is improved.
2012, 34(12): 2999-3005.
doi: 10.3724/SP.J.1146.2012.00160
Abstract:
A novel hybrid higher order Finite Difference Time Domain (FDTD) (2,4) and Modified Nodal Analysis (MNA) method for transient response of transmission line network is proposed. By constructing a hybrid single-port network model, the distributed parameter systems are separated from lumped circuits, so the higher-order FDTD (2,4) and MNA can be used to analysis of transmission line and port circuit transient response respectively. Different from former methods, the higher-order FDTD (2,4) can utilize coarser cell sizes for calculation of electrically long transmission lines because of the lower numerical dispersion errors. At the same time, direct using of circuit analysis method to solve the port circuits, the voltage and current wave processes of each node in the circuit can be obtained. Several sets of numerical examples validate the proposed method has higher accuracy and efficiency.
A novel hybrid higher order Finite Difference Time Domain (FDTD) (2,4) and Modified Nodal Analysis (MNA) method for transient response of transmission line network is proposed. By constructing a hybrid single-port network model, the distributed parameter systems are separated from lumped circuits, so the higher-order FDTD (2,4) and MNA can be used to analysis of transmission line and port circuit transient response respectively. Different from former methods, the higher-order FDTD (2,4) can utilize coarser cell sizes for calculation of electrically long transmission lines because of the lower numerical dispersion errors. At the same time, direct using of circuit analysis method to solve the port circuits, the voltage and current wave processes of each node in the circuit can be obtained. Several sets of numerical examples validate the proposed method has higher accuracy and efficiency.
2012, 34(12): 3006-3012.
doi: 10.3724/SP.J.1146.2012.00504
Abstract:
Because of existing Compressed-Sensing (CS) reconstruction algorithms have high computing complexity, a fast algorithm based on best linear estimate is proposed. It adaptively measures image data with a block-by-block manner at encoder, and reconstructs each block at decoder using the best linear operator which is constituted by statistical autocorrelation function matrix estimated according to various statistical property of image block. This algorithm replaces lots of nonlinear iterations in traditional CS reconstruction algorithm with linear projection, therefore it shorten the time of recovering image. Simulation experimental results indicate that the proposed algorithm not only reduces the time of rebuilding image, but also is better than the current popular CS reconstruction algorithm for images containing uncomplicated textures on the reconstructed image quality.
Because of existing Compressed-Sensing (CS) reconstruction algorithms have high computing complexity, a fast algorithm based on best linear estimate is proposed. It adaptively measures image data with a block-by-block manner at encoder, and reconstructs each block at decoder using the best linear operator which is constituted by statistical autocorrelation function matrix estimated according to various statistical property of image block. This algorithm replaces lots of nonlinear iterations in traditional CS reconstruction algorithm with linear projection, therefore it shorten the time of recovering image. Simulation experimental results indicate that the proposed algorithm not only reduces the time of rebuilding image, but also is better than the current popular CS reconstruction algorithm for images containing uncomplicated textures on the reconstructed image quality.
2012, 34(12): 3013-3020.
doi: 10.3724/SP.J.1146.2012.00652
Abstract:
High resolution terrain Digital Elevation Model (DEM) and orthophoto bring severely load including data storage, schedule and real-time rendering, etc.. A high performance terrain data compression method is proposed based on lifting wavelet transform and parallel hybrid entropy codec, and combined with Graphics Process Unit (GPU) Ray-casting to achieve large-scale 3D terrain visualization. First, the multi-resolution wavelet transform model of terrain tile is constructed to map the refinement and simplification operation. Then the multi-resolution quadtree of DEM and terrain texture is built separately based on lifting wavelet transform, the sparse wavelet coefficient generated from quantization is compressed by a hybrid entropy codec which combined with parallel run-length coding and variable-length Huffman coding. The compressed data are organized into progressive stream to do real-time decoding and rendering. The present lifting wavelet transform and hybrid entropy codec is implemented by Compute Unified Device Architecture (CUDA) in GPU. Experiment results show that the data compression ratio is effective with this method, PSNR and code-decode data throughput. High Frames Per Second (FPS) in real-time rendering satisfied the demand of interactive visualization.
High resolution terrain Digital Elevation Model (DEM) and orthophoto bring severely load including data storage, schedule and real-time rendering, etc.. A high performance terrain data compression method is proposed based on lifting wavelet transform and parallel hybrid entropy codec, and combined with Graphics Process Unit (GPU) Ray-casting to achieve large-scale 3D terrain visualization. First, the multi-resolution wavelet transform model of terrain tile is constructed to map the refinement and simplification operation. Then the multi-resolution quadtree of DEM and terrain texture is built separately based on lifting wavelet transform, the sparse wavelet coefficient generated from quantization is compressed by a hybrid entropy codec which combined with parallel run-length coding and variable-length Huffman coding. The compressed data are organized into progressive stream to do real-time decoding and rendering. The present lifting wavelet transform and hybrid entropy codec is implemented by Compute Unified Device Architecture (CUDA) in GPU. Experiment results show that the data compression ratio is effective with this method, PSNR and code-decode data throughput. High Frames Per Second (FPS) in real-time rendering satisfied the demand of interactive visualization.
2012, 34(12): 3021-3026.
doi: 10.3724/SP.J.1146.2012.00779
Abstract:
Compressive sensing theory is efficient to sampling and reconstruction for sparse signal. In this paper, acoustic signals carried less information are sampled deploying compressive sensing and a new impact-acoustics non-destructive test method is proposed, based on wavelet decomposition and compressive sensing. The stages are building the sensing matrix using wavelet decomposition, solving the l1 minimization, getting sparsity representation in classes and computing error of representation, followed by classification to obtain the results. Simulations and experiments show that the proposed method is practical and efficient, having good performance with corrective rate above 90% under the environment SNR 3 dB.
Compressive sensing theory is efficient to sampling and reconstruction for sparse signal. In this paper, acoustic signals carried less information are sampled deploying compressive sensing and a new impact-acoustics non-destructive test method is proposed, based on wavelet decomposition and compressive sensing. The stages are building the sensing matrix using wavelet decomposition, solving the l1 minimization, getting sparsity representation in classes and computing error of representation, followed by classification to obtain the results. Simulations and experiments show that the proposed method is practical and efficient, having good performance with corrective rate above 90% under the environment SNR 3 dB.
2012, 34(12): 3027-3033.
doi: 10.3724/SP.J.1146.2012.00557
Abstract:
In order to overcome the problem that the noise suppression ability of traditional small microphone arrays speech enhancement algorithm is limited, this paper proposes coherence spectral estimation based on the variable coefficients noise filter algorithm to suppress the reverberant interference, and then use the Generalized Sidelobe Canceler (GSC) which based on small microphone arrays canceller to suppress remaining noise and simulations and practical tests show that the proposed algorithm is superior to separate small array beamforming algorithms and coherence filter algorithm.
In order to overcome the problem that the noise suppression ability of traditional small microphone arrays speech enhancement algorithm is limited, this paper proposes coherence spectral estimation based on the variable coefficients noise filter algorithm to suppress the reverberant interference, and then use the Generalized Sidelobe Canceler (GSC) which based on small microphone arrays canceller to suppress remaining noise and simulations and practical tests show that the proposed algorithm is superior to separate small array beamforming algorithms and coherence filter algorithm.
2012, 34(12): 3034-3039.
doi: 10.3724/SP.J.1146.2012.00639
Abstract:
Due to the local ambiguities of images containing repetitive-patterns, it is difficult to match feature points reliably only by comparing similarity between local descriptors even if the disparity of viewpoint is not very large. Thus, a novel representation of geometric consistency named approximate distance order is proposed according to the space distribution of feature points. Then, an object function in hybrid form is defined by combining the matching cost of local descriptor, and the matching problem is formulated as an optimization problem with one-to-one correspondence constraints. Finally, the correspondences between feature points are obtained by maximizing the given object function via the method of probabilistic relaxation. Comparative experiments applied to various images demonstrate the algorithm is an effective approach to solving the suggested problem.
Due to the local ambiguities of images containing repetitive-patterns, it is difficult to match feature points reliably only by comparing similarity between local descriptors even if the disparity of viewpoint is not very large. Thus, a novel representation of geometric consistency named approximate distance order is proposed according to the space distribution of feature points. Then, an object function in hybrid form is defined by combining the matching cost of local descriptor, and the matching problem is formulated as an optimization problem with one-to-one correspondence constraints. Finally, the correspondences between feature points are obtained by maximizing the given object function via the method of probabilistic relaxation. Comparative experiments applied to various images demonstrate the algorithm is an effective approach to solving the suggested problem.
2012, 34(12): 3040-3045.
doi: 10.3724/SP.J.1146.2012.00701
Abstract:
A novel algorithm for incomplete fingerprint recognition is proposed in this paper using fusion features and pattern entropy based similarity measure. Because of incomplete fingerprints unique characteristic of information loss, the recognition performance is mainly restricted by two critical problems: extracting features containing sufficient information and measuring similarity more effectively. For the first problem, minutiae and orientation field features are fused to get more comprehensive information and to improve the scale and rotation invariability. For the second, the pattern entropy is introduced to measure the coherency of correspondences between two feature sets to eliminate false match. The extensive experiments are done and compared with existing method on fingerprint databases and made thorough comparisons. Experimental results show that the proposed scheme has more efficient ability on separating genuine and impostor pairs and performs well in both accuracy and speed.
A novel algorithm for incomplete fingerprint recognition is proposed in this paper using fusion features and pattern entropy based similarity measure. Because of incomplete fingerprints unique characteristic of information loss, the recognition performance is mainly restricted by two critical problems: extracting features containing sufficient information and measuring similarity more effectively. For the first problem, minutiae and orientation field features are fused to get more comprehensive information and to improve the scale and rotation invariability. For the second, the pattern entropy is introduced to measure the coherency of correspondences between two feature sets to eliminate false match. The extensive experiments are done and compared with existing method on fingerprint databases and made thorough comparisons. Experimental results show that the proposed scheme has more efficient ability on separating genuine and impostor pairs and performs well in both accuracy and speed.
2012, 34(12): 3046-3050.
doi: 10.3724/SP.J.1146.2012.00535
Abstract:
Video forgeries can be effectively detected by discriminating double MPEG compression, in order to authenticate the truism and reliability of digital videos. Through delving into the fitting results of the first digit distribution of Alternating Current (AC) coefficients with logarithmic law, a double MPEG compression detection algorithm is proposed by extracting a 12-D first digit feature and employing Support Vector Machine (SVM). Experiments show that this algorithm has high accuracy and efficiency.
Video forgeries can be effectively detected by discriminating double MPEG compression, in order to authenticate the truism and reliability of digital videos. Through delving into the fitting results of the first digit distribution of Alternating Current (AC) coefficients with logarithmic law, a double MPEG compression detection algorithm is proposed by extracting a 12-D first digit feature and employing Support Vector Machine (SVM). Experiments show that this algorithm has high accuracy and efficiency.
