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2011 Vol. 33, No. 3
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2011, 33(3): 509-514.
doi: 10.3724/SP.J.1146.2010.00465
Abstract:
Cognitive Radio Networks (CRNs) improve Secondary Users (SUs) transmission performance through cooperative transmission between SUs without interfering the regular transmissions of the Primary Users (PU). In this paper, a new cooperative transmission scheme is proposed based on AF (Amplify and Forward) protocol while PU and SUs coexist in the same CRN and each PU can be either active (ON) or inactive (OFF) in any given slot. When the licensed frequency is occupied by the PU, SU can opportunist use the relay to transmit signals. Analytical expression of the non-interference transmission durations is given. Non-cooperative and cooperative schemes derived show the effect of cooperative transmission on the non-interference transmission durations performance. Besides, numerical experiments are conducted to verify the effectiveness of the proposed cooperative schemes. The increase of non-interference transmission durations by cooperative transmission confirms the advantages of the new scheme.
Cognitive Radio Networks (CRNs) improve Secondary Users (SUs) transmission performance through cooperative transmission between SUs without interfering the regular transmissions of the Primary Users (PU). In this paper, a new cooperative transmission scheme is proposed based on AF (Amplify and Forward) protocol while PU and SUs coexist in the same CRN and each PU can be either active (ON) or inactive (OFF) in any given slot. When the licensed frequency is occupied by the PU, SU can opportunist use the relay to transmit signals. Analytical expression of the non-interference transmission durations is given. Non-cooperative and cooperative schemes derived show the effect of cooperative transmission on the non-interference transmission durations performance. Besides, numerical experiments are conducted to verify the effectiveness of the proposed cooperative schemes. The increase of non-interference transmission durations by cooperative transmission confirms the advantages of the new scheme.
2011, 33(3): 515-520.
doi: 10.3724/SP.J.1146.2010.00658
Abstract:
Focusing on the V-BLAST OFDM system with distributed transmit antennas in multipath fading channel, a novel signal transmission method utilizing spatial power spreading is proposed. The method takes advantage of the delays among distributed antennas and enhances frequency selectivity of the distributed channel. Thus, the achievable diversity increases. Simulation results in M.1225 pedestrian test channel show that the proposed algorithm has 2 dB gain at BER of10-3 compared to conventional method using BPSK modulation.
Focusing on the V-BLAST OFDM system with distributed transmit antennas in multipath fading channel, a novel signal transmission method utilizing spatial power spreading is proposed. The method takes advantage of the delays among distributed antennas and enhances frequency selectivity of the distributed channel. Thus, the achievable diversity increases. Simulation results in M.1225 pedestrian test channel show that the proposed algorithm has 2 dB gain at BER of10-3 compared to conventional method using BPSK modulation.
2011, 33(3): 521-526.
doi: 10.3724/SP.J.1146.2010.00479
Abstract:
For a cognitive radio communication system coexisting with radar to access the radar spectrum opportunistically, an efficient Cooperative Sensing Algorithm (CSA) for swept radar pulse train is proposed. There is a central processing node which cooperates with other sensing nodes to sense a radar spectrum channel. Moreover, the similarity judgment of the single node and data fusion based on time-series identification of the central processing node can greatly improve the probability of detection and reduce the probability of false alarm. Compared to existing methods of sensing radar signal, the proposed algorithm can quickly and reliably detect swept radar pulse train without any prior information on the radar. At the same time, the radar parameters, such as rotation period, scanning direction, distance etc., can be acquired. Finally, simulation results show the effectiveness and correctness of the algorithm.
For a cognitive radio communication system coexisting with radar to access the radar spectrum opportunistically, an efficient Cooperative Sensing Algorithm (CSA) for swept radar pulse train is proposed. There is a central processing node which cooperates with other sensing nodes to sense a radar spectrum channel. Moreover, the similarity judgment of the single node and data fusion based on time-series identification of the central processing node can greatly improve the probability of detection and reduce the probability of false alarm. Compared to existing methods of sensing radar signal, the proposed algorithm can quickly and reliably detect swept radar pulse train without any prior information on the radar. At the same time, the radar parameters, such as rotation period, scanning direction, distance etc., can be acquired. Finally, simulation results show the effectiveness and correctness of the algorithm.
2011, 33(3): 527-532.
doi: 10.3724/SP.J.1146.2010.00659
Abstract:
As the protection distance is limited, ultra-wideband signals may still interfere another communication system even with the satisfaction of the power spectral density limit. This paper derives the common expressions of bit error rate of another communication system without spread spectrum under the interference of the four ultra-wideband spread spectrum signals which pass through AWGN channel, and the four ultra-wideband spread spectrum schemes are direct sequence spread spectrum, time-hopping spread spectrum, frequency-hopping spread spectrum and chirp spread spectrum. The derived expressions are validated by Monte Carlo simulations. Also provided here are the simulation results obtained when ultra-wideband spread spectrum signals pass through IEEE 802.15.3a CM4 channel. The conclusions can be used as important references for the electromagnetic compatibility performance evaluation and the selection of spread spectrum schemes of ultra-wideband systems.
As the protection distance is limited, ultra-wideband signals may still interfere another communication system even with the satisfaction of the power spectral density limit. This paper derives the common expressions of bit error rate of another communication system without spread spectrum under the interference of the four ultra-wideband spread spectrum signals which pass through AWGN channel, and the four ultra-wideband spread spectrum schemes are direct sequence spread spectrum, time-hopping spread spectrum, frequency-hopping spread spectrum and chirp spread spectrum. The derived expressions are validated by Monte Carlo simulations. Also provided here are the simulation results obtained when ultra-wideband spread spectrum signals pass through IEEE 802.15.3a CM4 channel. The conclusions can be used as important references for the electromagnetic compatibility performance evaluation and the selection of spread spectrum schemes of ultra-wideband systems.
2011, 33(3): 533-536.
doi: 10.3724/SP.J.1146.2010.00671
Abstract:
A new technique of joint estimation of Carrier Frequency Offsets (CFOs) is proposed based on maximum-likelihood estimation using two distributed receive antennas helping for each other for flat-fading Rayleigh channels. By utilizing the prior information of the carrier frequency, the oscillators accuracy of transceiver antennas and the maximum speed of mobile station, the range of the difference of two CFOs is determined. Taking advantage of this result, when joint searching correlation outputs from two distributed receive antennas, the frequency searching range can be reduced compared with existing methods. Simulation results show that when the Signal-to-Noise Ratio (SNR) is 5 dB, the Mean-Square Error (MSE) performance of joint CFOs estimation outweighs existing algorithms by more than one order of magnitude on condition that the carrier frequency is 2 GHz, the oscillators accuracy of transmit antenna is 10 ppm, the oscillators accuracy of distributed receive antennas is 1 ppm and the maximum mobile speed is 120 km/h.
A new technique of joint estimation of Carrier Frequency Offsets (CFOs) is proposed based on maximum-likelihood estimation using two distributed receive antennas helping for each other for flat-fading Rayleigh channels. By utilizing the prior information of the carrier frequency, the oscillators accuracy of transceiver antennas and the maximum speed of mobile station, the range of the difference of two CFOs is determined. Taking advantage of this result, when joint searching correlation outputs from two distributed receive antennas, the frequency searching range can be reduced compared with existing methods. Simulation results show that when the Signal-to-Noise Ratio (SNR) is 5 dB, the Mean-Square Error (MSE) performance of joint CFOs estimation outweighs existing algorithms by more than one order of magnitude on condition that the carrier frequency is 2 GHz, the oscillators accuracy of transmit antenna is 10 ppm, the oscillators accuracy of distributed receive antennas is 1 ppm and the maximum mobile speed is 120 km/h.
2011, 33(3): 537-542.
doi: 10.3724/SP.J.1146.2010.00670
Abstract:
A sorting approach for Scalable Video Coding (SVC) streaming is proposed for video transmission. By the accurate states selection and the effective approximate distortion calculation of the fully scalable video streaming, the proposed approach can priority transmit the scalable streaming owning better rate-distortion performance, which improves effectively the reconstructed quality of video streaming. A state model is built to select layered streaming from the fully scalable video streaming, and the distortion approximate formula of the scalable streaming is deduced. The scalable streaming is reordered by employing the rate-distortion optimization under certain bandwidth limitations. The simulation results show that the proposed approach can improve the reconstructed quality of video streaming.
A sorting approach for Scalable Video Coding (SVC) streaming is proposed for video transmission. By the accurate states selection and the effective approximate distortion calculation of the fully scalable video streaming, the proposed approach can priority transmit the scalable streaming owning better rate-distortion performance, which improves effectively the reconstructed quality of video streaming. A state model is built to select layered streaming from the fully scalable video streaming, and the distortion approximate formula of the scalable streaming is deduced. The scalable streaming is reordered by employing the rate-distortion optimization under certain bandwidth limitations. The simulation results show that the proposed approach can improve the reconstructed quality of video streaming.
2011, 33(3): 543-548.
doi: 10.3724/SP.J.1146.2010.00455
Abstract:
To reduce the distortion in the video coding, the two-step method for distortion compensation in video coding is proposed. Firstly, the DC offset of the reconstructed picture is compensated. Then, the adaptive compensation filter is designed for processing the picture to reduce further AC part of the distortion in the video coding. Experimental results demonstrate that the two-step distortion compensation outperforms the existing algorithm of adaptive loop filter with different resolution sequences. The coding efficiency is improved up to 26.31% compared with H.264/AVC. In addition, with the feature that the sum of the tap coeffients of the adaptive compensation filter equals 1, the modified algorithm for quantization and codec of the filter coefficients is proposed. The redundancy of the description of the filter coefficients is reduced.
To reduce the distortion in the video coding, the two-step method for distortion compensation in video coding is proposed. Firstly, the DC offset of the reconstructed picture is compensated. Then, the adaptive compensation filter is designed for processing the picture to reduce further AC part of the distortion in the video coding. Experimental results demonstrate that the two-step distortion compensation outperforms the existing algorithm of adaptive loop filter with different resolution sequences. The coding efficiency is improved up to 26.31% compared with H.264/AVC. In addition, with the feature that the sum of the tap coeffients of the adaptive compensation filter equals 1, the modified algorithm for quantization and codec of the filter coefficients is proposed. The redundancy of the description of the filter coefficients is reduced.
2011, 33(3): 549-554.
doi: 10.3724/SP.J.1146.2009.01615
Abstract:
A new method of construction of shift sequences is presented by setting different parameters to shift sequences. With these shift sequences, a class of sequence sets is got with flexible zero or low correlation zone whose set sizes can reach or approach the theoretical bound through interleaving technique, the proposed method can be used to construct more sequence sets suitable for QS-CDMA systems.
A new method of construction of shift sequences is presented by setting different parameters to shift sequences. With these shift sequences, a class of sequence sets is got with flexible zero or low correlation zone whose set sizes can reach or approach the theoretical bound through interleaving technique, the proposed method can be used to construct more sequence sets suitable for QS-CDMA systems.
2011, 33(3): 555-562.
doi: 10.3724/SP.J.1146.2010.00409
Abstract:
From the view of differentiated service and load balancing, this paper proposes and implements a load balancing cluster architecture supported differentiated service. By system identification and resource optimal control, the front-end dispatcher can adjust the resource quotas assigned to different classes in every single back-end server, and Multi-class based Maximum Idle First (MIF) load balancing strategy is designed to ensure every class a fair consumption among back-end nodes. As a result, the end-to-end delay is controlled and proportional delay is guaranteed. The experiments demonstrate that no matter using Round-Robin (RR), Least Connection Schedule (LCS) or Maximum Idle First load balancing strategy, the proposed resource optimal controller can hold the relationship between different classes. Compared to Round-Robin and Least-Connection First Schedule, Maximum Idle First strategy increases the total throughput by 25% and reduces the average delay by 33%.
From the view of differentiated service and load balancing, this paper proposes and implements a load balancing cluster architecture supported differentiated service. By system identification and resource optimal control, the front-end dispatcher can adjust the resource quotas assigned to different classes in every single back-end server, and Multi-class based Maximum Idle First (MIF) load balancing strategy is designed to ensure every class a fair consumption among back-end nodes. As a result, the end-to-end delay is controlled and proportional delay is guaranteed. The experiments demonstrate that no matter using Round-Robin (RR), Least Connection Schedule (LCS) or Maximum Idle First load balancing strategy, the proposed resource optimal controller can hold the relationship between different classes. Compared to Round-Robin and Least-Connection First Schedule, Maximum Idle First strategy increases the total throughput by 25% and reduces the average delay by 33%.
2011, 33(3): 563-568.
doi: 10.3724/SP.J.1146.2010.00560
Abstract:
The communication between nodes is designed to meet the low consumption of resources, large carrier frequency offset, low-cost physical layer requirements because nodes are generally subject to resource, cost and power consumption constraints in wireless sensor networks. This paper presents a new fast acquisition method which uses Parallel Search Pseudo-code phase and Frequency offset based on FFT (PSPF-FFT). It firstly searches the pseudo-code phase after differential processing of the signal, then it searches frequency offset after pseudo-code phase is synchronized. The reduction of resource and average acquisition time can be achieved by sacrificing a slight performance of signal-to-noise ratio (SNR). The theoretical analysis and simulation prove the practicability of the new acquisition method. The proposed method in this paper has obvious performance advantages compared to the traditional method with the same resource and average acquisition time consumption.
The communication between nodes is designed to meet the low consumption of resources, large carrier frequency offset, low-cost physical layer requirements because nodes are generally subject to resource, cost and power consumption constraints in wireless sensor networks. This paper presents a new fast acquisition method which uses Parallel Search Pseudo-code phase and Frequency offset based on FFT (PSPF-FFT). It firstly searches the pseudo-code phase after differential processing of the signal, then it searches frequency offset after pseudo-code phase is synchronized. The reduction of resource and average acquisition time can be achieved by sacrificing a slight performance of signal-to-noise ratio (SNR). The theoretical analysis and simulation prove the practicability of the new acquisition method. The proposed method in this paper has obvious performance advantages compared to the traditional method with the same resource and average acquisition time consumption.
2011, 33(3): 569-574.
doi: 10.3724/SP.J.1146.2010.00529
Abstract:
The possibility of occurring exception is relatively small in most applications of wireless sensor networks. So data obtained in sequent moment by the same node have time correlation, and data obtained in the same time by adjacent nodes have space correlation. A large number of energy of node will be wasted if data which include time and space correlation is transmitted. Therefore, this paper proposed a data compression algorithm for wireless sensor networks based on optimal order estimation and distributed clustering. The algorithm explores the time and space correlation among data obtained by sensors. The correlation parameter can be get based on optimal order estimation. Then all data can be restored based on time and space correlation parameters and only a little necessary data are transmitted by nodes. Because redundancy is decreased when data is transmitted, the average energy cost of node is reduced and the life of the whole wireless sensor networks can be extended.
The possibility of occurring exception is relatively small in most applications of wireless sensor networks. So data obtained in sequent moment by the same node have time correlation, and data obtained in the same time by adjacent nodes have space correlation. A large number of energy of node will be wasted if data which include time and space correlation is transmitted. Therefore, this paper proposed a data compression algorithm for wireless sensor networks based on optimal order estimation and distributed clustering. The algorithm explores the time and space correlation among data obtained by sensors. The correlation parameter can be get based on optimal order estimation. Then all data can be restored based on time and space correlation parameters and only a little necessary data are transmitted by nodes. Because redundancy is decreased when data is transmitted, the average energy cost of node is reduced and the life of the whole wireless sensor networks can be extended.
2011, 33(3): 575-579.
doi: 10.3724/SP.J.1146.2010.00410
Abstract:
The characteristic of loose connectivity of Delay Tolerant Network (DTN) is a huge challenge for data delivery. All of the routing methods do not thoroughly use the status of the peer, so SARM (Situation-Aware Routing Method) is proposed. SARM estimates the delivery probability of a peer according to the peers situation, and copies the message to its neighbor whose delivery probability is bigger. A queue management method is proposed according to the messages age, time of left and the number of copies. Simulation shows that SARM achieves a higher message delivery ratio and lower delivery delay without more transmission overhead.
The characteristic of loose connectivity of Delay Tolerant Network (DTN) is a huge challenge for data delivery. All of the routing methods do not thoroughly use the status of the peer, so SARM (Situation-Aware Routing Method) is proposed. SARM estimates the delivery probability of a peer according to the peers situation, and copies the message to its neighbor whose delivery probability is bigger. A queue management method is proposed according to the messages age, time of left and the number of copies. Simulation shows that SARM achieves a higher message delivery ratio and lower delivery delay without more transmission overhead.
2011, 33(3): 580-586.
doi: 10.3724/SP.J.1146.2010.00533
Abstract:
Petri nets is a modeling and analyzing mathematical tool based on graphic, which can be used efficiently in describing the asynchronous and concurrent behaviors of system. However, existing advance Petri nets are incapable of modeling and analyzing embedded real-time system completely. Hierarchical Real-Time Coloured Petri Net is introduced by extending the definition of coloured Petri net, and methodology of modeling and real-time analysis of embedded real-time system are proposed. As a confirmation of its validity, the methodology described in this paper has been successfully applied to modeling and real-time analysis of MVB (Multifunction Vehicle Bus) device, which can satisfy the requirements about functional verification and timing analysis of system design.
Petri nets is a modeling and analyzing mathematical tool based on graphic, which can be used efficiently in describing the asynchronous and concurrent behaviors of system. However, existing advance Petri nets are incapable of modeling and analyzing embedded real-time system completely. Hierarchical Real-Time Coloured Petri Net is introduced by extending the definition of coloured Petri net, and methodology of modeling and real-time analysis of embedded real-time system are proposed. As a confirmation of its validity, the methodology described in this paper has been successfully applied to modeling and real-time analysis of MVB (Multifunction Vehicle Bus) device, which can satisfy the requirements about functional verification and timing analysis of system design.
2011, 33(3): 587-591.
doi: 10.3724/SP.J.1146.2010.00622
Abstract:
Group Authenticated Key Exchange (GAKE) protocols allow two or more parties to generate a common group session key in public channel. Considering users different computing power, a new GAKE protocol is proposed for imbalanced wireless network and its security is proved in the random oracle model. In additional, the protocol can resist ephemeral key compromise attack and any two users can generate a two-party session key using the information of group stage. Compared with other GAKE protocols for imbalanced wireless network, the proposed protocol has stronger security.
Group Authenticated Key Exchange (GAKE) protocols allow two or more parties to generate a common group session key in public channel. Considering users different computing power, a new GAKE protocol is proposed for imbalanced wireless network and its security is proved in the random oracle model. In additional, the protocol can resist ephemeral key compromise attack and any two users can generate a two-party session key using the information of group stage. Compared with other GAKE protocols for imbalanced wireless network, the proposed protocol has stronger security.
2011, 33(3): 592-596.
doi: 10.3724/SP.J.1146.2010.00427
Abstract:
This paper presents a novel double-layered embedding steganographic algorithm based on steganographic codes, wet paper codes and graphic matching theory, which can achieve high embedding efficiency and preserve the first-order histogram of the cover image. At first, a new 4-ary steganographic channel is constructed. Then the secret message is embedded in the LSB (Least Significant Bit) layer of this channel using binary steganographic codes and in the second LSB layer using wet paper codes, and the elements that need to be changed, are obtained. Afterwards, a graph is constructed. Then a changing manner of the cover image is found to decrease the distortion and preserve the histogram, using the matching algorithm in graph theory. The performance analysis and experimental results show that PSNR, the embedding efficiency and the ability to preserve the first-order histogram of the proposed algorithm are better than the steganographic software Steghide, when the same amount of secret message is embedded.
This paper presents a novel double-layered embedding steganographic algorithm based on steganographic codes, wet paper codes and graphic matching theory, which can achieve high embedding efficiency and preserve the first-order histogram of the cover image. At first, a new 4-ary steganographic channel is constructed. Then the secret message is embedded in the LSB (Least Significant Bit) layer of this channel using binary steganographic codes and in the second LSB layer using wet paper codes, and the elements that need to be changed, are obtained. Afterwards, a graph is constructed. Then a changing manner of the cover image is found to decrease the distortion and preserve the histogram, using the matching algorithm in graph theory. The performance analysis and experimental results show that PSNR, the embedding efficiency and the ability to preserve the first-order histogram of the proposed algorithm are better than the steganographic software Steghide, when the same amount of secret message is embedded.
2011, 33(3): 597-603.
doi: 10.3724/SP.J.1146.2010.00943
Abstract:
Stereo vision system plays important role in three-dimensional information perception. Due to the high computational complexity, real-time processing of stereo vision needs to use dedicated hardware. However, performance requirements conflict with hardware resources in existing implementations. With the resolution increased, system requires larger disparity range and higher processing speed. In this paper, a stereo vision implementation is proposed using fine-grain pipelined structure and sub-module parallelism to improve performance. The implemented matching algorithm used adaptive correlation window strategy to raise disparity quality at object borders and integrated left-right consistency check to reduce possible errors in general. The entire stereo matching process is realized using a single chip of Field Programmable Gate Array (FPGA) and extended disparity search range to 128 pixels under limited resources. The matching process is capable of generating disparities at more than 60 frames per second on 512512 images when clocked at 60 MHz.
Stereo vision system plays important role in three-dimensional information perception. Due to the high computational complexity, real-time processing of stereo vision needs to use dedicated hardware. However, performance requirements conflict with hardware resources in existing implementations. With the resolution increased, system requires larger disparity range and higher processing speed. In this paper, a stereo vision implementation is proposed using fine-grain pipelined structure and sub-module parallelism to improve performance. The implemented matching algorithm used adaptive correlation window strategy to raise disparity quality at object borders and integrated left-right consistency check to reduce possible errors in general. The entire stereo matching process is realized using a single chip of Field Programmable Gate Array (FPGA) and extended disparity search range to 128 pixels under limited resources. The matching process is capable of generating disparities at more than 60 frames per second on 512512 images when clocked at 60 MHz.
2011, 33(3): 604-609.
doi: 10.3724/SP.J.1146.2010.00417
Abstract:
In order to improve the performance of sparse system identification, the l0 norm constraint LMS algorithm is studied and improved in this paper. Firstly, the convergence of the algorithm is accelerated by the introduction of a step size control method based on the status information provided by mean square estimation error. Secondly, the zero attraction item is reweighted by the absolute estimation error to reduce the steady-state misalignment. Then the parameters in the proposed algorithm, which control the convergence and steady-state misalignment, are discussed qualitatively. Finally, the simulations demonstrate that the proposed algorithm significantly outperforms l0-LMS and several other existing sparse system identification algorithms.
In order to improve the performance of sparse system identification, the l0 norm constraint LMS algorithm is studied and improved in this paper. Firstly, the convergence of the algorithm is accelerated by the introduction of a step size control method based on the status information provided by mean square estimation error. Secondly, the zero attraction item is reweighted by the absolute estimation error to reduce the steady-state misalignment. Then the parameters in the proposed algorithm, which control the convergence and steady-state misalignment, are discussed qualitatively. Finally, the simulations demonstrate that the proposed algorithm significantly outperforms l0-LMS and several other existing sparse system identification algorithms.
A GPU-based Parallel Implementation of Compressive Sampling Reconstruction for SAR Image Compression
2011, 33(3): 610-615.
doi: 10.3724/SP.J.1146.2010.00461
Abstract:
Compressive Sampling (CS) technique has been adopted to compress Synthetic Aperture Radar (SAR) images. However, due to the mass data of high resolution SAR images, the reconstruction of compressive sampling generates huge computational load, making it impossible to run on traditional CPU at real time. To solve this problem, this paper attempts to implement the reconstruction produce in parallel based on Graphics Processing Unit (GPU) device. The results show that the GPU-based implementation is faster (up to 8.8 times) than the CPU-based implementation.
Compressive Sampling (CS) technique has been adopted to compress Synthetic Aperture Radar (SAR) images. However, due to the mass data of high resolution SAR images, the reconstruction of compressive sampling generates huge computational load, making it impossible to run on traditional CPU at real time. To solve this problem, this paper attempts to implement the reconstruction produce in parallel based on Graphics Processing Unit (GPU) device. The results show that the GPU-based implementation is faster (up to 8.8 times) than the CPU-based implementation.
2011, 33(3): 616-621.
doi: 10.3724/SP.J.1146.2010.00625
Abstract:
A novel passive radar imaging method is presented using distributed apertures that relies on illuminators of opportunity. The measurement is modeled using the wave equation. A new passive measurement model is proposed that expresses the measurement at a receiver in terms of the measurement at a different receiver and therefore requires no information about the illumination sources. Since only a limited number of measurements are available due to sparsely and randomly distributed apertures, the imaging issue is formulated as a binary hypothesis test with unknown target location. The spatial-resolved test-statistic is determined by maximizing the SNR of the test-statistic using the proposed passive measurement model. The resulting image is formed with the test-statistics evaluated at each hypothetical target location, which can provide the information about the target location. The resolution analysis of the imaging method is presented and numerical simulations are conducted to verify its performance and validate the theoretical findings.
A novel passive radar imaging method is presented using distributed apertures that relies on illuminators of opportunity. The measurement is modeled using the wave equation. A new passive measurement model is proposed that expresses the measurement at a receiver in terms of the measurement at a different receiver and therefore requires no information about the illumination sources. Since only a limited number of measurements are available due to sparsely and randomly distributed apertures, the imaging issue is formulated as a binary hypothesis test with unknown target location. The spatial-resolved test-statistic is determined by maximizing the SNR of the test-statistic using the proposed passive measurement model. The resulting image is formed with the test-statistics evaluated at each hypothetical target location, which can provide the information about the target location. The resolution analysis of the imaging method is presented and numerical simulations are conducted to verify its performance and validate the theoretical findings.
2011, 33(3): 622-627.
doi: 10.3724/SP.J.1146.2010.00904
Abstract:
Due to the variational flight path during the diving maneuver, the range function of the point target for the missile-borne SAR becomes complicated. Thus, a new imaging method is proposed in this paper. Firstly, the target range function is expanded to a quartic polynomial. Secondly, the stationary point is solved via the Cardanos formula, and then the tow-dimensional spectrum is obtained, based on which a new imaging algorithm is derived. Finally, the simulation result of the point targets shows that the algorithm proposed is effective to give a high resolution imagery with the entire aperture of the missile-borne SAR than the traditional method.
Due to the variational flight path during the diving maneuver, the range function of the point target for the missile-borne SAR becomes complicated. Thus, a new imaging method is proposed in this paper. Firstly, the target range function is expanded to a quartic polynomial. Secondly, the stationary point is solved via the Cardanos formula, and then the tow-dimensional spectrum is obtained, based on which a new imaging algorithm is derived. Finally, the simulation result of the point targets shows that the algorithm proposed is effective to give a high resolution imagery with the entire aperture of the missile-borne SAR than the traditional method.
2011, 33(3): 628-633.
doi: 10.3724/SP.J.1146.2010.00575
Abstract:
An advanced algorithm is proposed to obtain forward-target image on a curve trajectory, which causes a serious range coupling. The algorithm decreases efficiently the coupling with Range Walk Correction (RCM) in time domain firstly. The 2-dimision frequency domain expression is presented with series reversion. The correlative coefficient of ECS algorithm is obtained, and SAR image is got with ECS. Finally simulations show the validity of the proposed algorithm.
An advanced algorithm is proposed to obtain forward-target image on a curve trajectory, which causes a serious range coupling. The algorithm decreases efficiently the coupling with Range Walk Correction (RCM) in time domain firstly. The 2-dimision frequency domain expression is presented with series reversion. The correlative coefficient of ECS algorithm is obtained, and SAR image is got with ECS. Finally simulations show the validity of the proposed algorithm.
2011, 33(3): 634-641.
doi: 10.3724/SP.J.1146.2010.00491
Abstract:
A novel forward-looking SAR three-dimension imaging method based on interferometric technology through different snapshots is proposed in this paper. Practical linear array antennas are laid to achieve high azimuth resolution in azimuth dimension and each high resolution snapshot in two dimensions is achieved corresponding to only one transmitted pulse. The interferometric phase information is extracted from snapshots with different squint angles for height estimation through multi-baseline interferometric technology. The main characteristics of the proposed three-dimension imaging method lie in both short data acquisition time, low data amount and computational load. Meanwhile, signal-to-noise ratio is improved through multi-baseline InSAR combined pixels method to ensure high height precision. Numeric simulation results confirm the validation of the proposal.
A novel forward-looking SAR three-dimension imaging method based on interferometric technology through different snapshots is proposed in this paper. Practical linear array antennas are laid to achieve high azimuth resolution in azimuth dimension and each high resolution snapshot in two dimensions is achieved corresponding to only one transmitted pulse. The interferometric phase information is extracted from snapshots with different squint angles for height estimation through multi-baseline interferometric technology. The main characteristics of the proposed three-dimension imaging method lie in both short data acquisition time, low data amount and computational load. Meanwhile, signal-to-noise ratio is improved through multi-baseline InSAR combined pixels method to ensure high height precision. Numeric simulation results confirm the validation of the proposal.
2011, 33(3): 642-645.
doi: 10.3724/SP.J.1146.2010.00733
Abstract:
For the problem of CFAR (Constant False Alarm Rate) detection in clutter, a new detector, i.e., the Blind-CFAR detector is proposed. The Blind-CFAR detector calculates its detection threshold through the PDF (Probability Density Function) estimation of clutter, which is based on the fractional moment estimations of clutter and the maximum entropy method. The Blind-CFAR detector is verified in Weibull clutter through simulation experiments. By employing nonparametric estimation methods, the Blind-CFAR detector has advantages of a simple structure, a good universality, etc. Furthermore, it can be applied to target detection in unknown clutter.
For the problem of CFAR (Constant False Alarm Rate) detection in clutter, a new detector, i.e., the Blind-CFAR detector is proposed. The Blind-CFAR detector calculates its detection threshold through the PDF (Probability Density Function) estimation of clutter, which is based on the fractional moment estimations of clutter and the maximum entropy method. The Blind-CFAR detector is verified in Weibull clutter through simulation experiments. By employing nonparametric estimation methods, the Blind-CFAR detector has advantages of a simple structure, a good universality, etc. Furthermore, it can be applied to target detection in unknown clutter.
2011, 33(3): 646-651.
doi: 10.3724/SP.J.1146.2010.00416
Abstract:
This paper focuses on the effect of arbitrary transmitted waveform on clutter characteristics for airborne MIMO radar. Transmit waveform synthesis model is established by the transformation for signal space and sensor space. The uniform model of space time clutter is presented for airborne MIMO Radar, and the relation ship between signal waveform synthesis and the uniform model is expatiated. Clutter characteristics are analyzed in the simulations for arbitrary waveforms including coherent, correlated and orthogonal waveforms. It is found that the degree of clutter broaden is determined by the structure of signal cross-correlation matrix, and the clutter degree of freedom (DOF) is determined by the rank of the cross-correlation matrix. The uniform model is the foundation for the design of STAP algorithm.
This paper focuses on the effect of arbitrary transmitted waveform on clutter characteristics for airborne MIMO radar. Transmit waveform synthesis model is established by the transformation for signal space and sensor space. The uniform model of space time clutter is presented for airborne MIMO Radar, and the relation ship between signal waveform synthesis and the uniform model is expatiated. Clutter characteristics are analyzed in the simulations for arbitrary waveforms including coherent, correlated and orthogonal waveforms. It is found that the degree of clutter broaden is determined by the structure of signal cross-correlation matrix, and the clutter degree of freedom (DOF) is determined by the rank of the cross-correlation matrix. The uniform model is the foundation for the design of STAP algorithm.
2011, 33(3): 652-658.
doi: 10.3724/SP.J.1146.2010.00446
Abstract:
In order to make use of a prior information about target motion state, this paper applies coupling of detection and tracking based on Bayesian theory to the process of relay of tracking, which can enhance the performance of target detection and tracking for the system of relay of tracking. In addition, this paper presents a simplified version to reduce the complexity of computation of the system. The simplified version can take advantage of the characteristic of coupling of detection and tracking based on Bayesian theory, and can determine the number of tracking points according to the ability of computation of the system. The simulation results show that the performance of the system of relay of tracking can be improved by coupling of detection and tracking based on Bayesian theory.
In order to make use of a prior information about target motion state, this paper applies coupling of detection and tracking based on Bayesian theory to the process of relay of tracking, which can enhance the performance of target detection and tracking for the system of relay of tracking. In addition, this paper presents a simplified version to reduce the complexity of computation of the system. The simplified version can take advantage of the characteristic of coupling of detection and tracking based on Bayesian theory, and can determine the number of tracking points according to the ability of computation of the system. The simulation results show that the performance of the system of relay of tracking can be improved by coupling of detection and tracking based on Bayesian theory.
2011, 33(3): 659-664.
doi: 10.3724/SP.J.1146.2010.00451
Abstract:
This paper proposes a multi-transmitter and multi-receiver SAR imaging algorithm based on Kalman filtering. In the algorithm, the application of multi-transmitter and multi-receiver offer more information about the scene and unambiguous wide swath is achieved by reducing PRF. Orthogonal coding is used in multi-transmitter channels. Kalman filtering perfectly reconstructs the scene with fine resolution and the principle of MMSE resolves the problem of ambiguity caused by orthogonal waveforms. The proposed imaging algorithm is justified by theoretic analyses and validated by digital simulations.
This paper proposes a multi-transmitter and multi-receiver SAR imaging algorithm based on Kalman filtering. In the algorithm, the application of multi-transmitter and multi-receiver offer more information about the scene and unambiguous wide swath is achieved by reducing PRF. Orthogonal coding is used in multi-transmitter channels. Kalman filtering perfectly reconstructs the scene with fine resolution and the principle of MMSE resolves the problem of ambiguity caused by orthogonal waveforms. The proposed imaging algorithm is justified by theoretic analyses and validated by digital simulations.
2011, 33(3): 665-671.
doi: 10.3724/SP.J.1146.2010.00525
Abstract:
In through-the-wall SAR imaging, the quality and reliability of the image are governed by the knowledge of wall parameters. Estimation error in wall parameters smears the image, and also causes targets to be imaged away from their true positions. In this paper, the effects of wall-parameter error are analyzed and an autofocusing technique is presented. The technique is based on the Product High-order Ambiguity Function (PHAF) algorithm, which improves the estimation of wall parameters. Simulation results show that this method yields focused images of high quality and the obtained wall parameters are very close to their true values.
In through-the-wall SAR imaging, the quality and reliability of the image are governed by the knowledge of wall parameters. Estimation error in wall parameters smears the image, and also causes targets to be imaged away from their true positions. In this paper, the effects of wall-parameter error are analyzed and an autofocusing technique is presented. The technique is based on the Product High-order Ambiguity Function (PHAF) algorithm, which improves the estimation of wall parameters. Simulation results show that this method yields focused images of high quality and the obtained wall parameters are very close to their true values.
2011, 33(3): 672-676.
doi: 10.3724/SP.J.1146.2010.00518
Abstract:
Recent theory of Compressed Sensing (CS) suggests that exact recovery of an unknown sparse signal can be achieved from few measurements with overwhelming probability. In this paper, CS technology is combined with random noise radar and the concept of random noise radar is proposed based on CS. The block diagram of the radar system is presented. Detailed analysis show that the sensing matrix of the random noise radar based on CS exerts good Restricted Isometry Property (RIP). Given a sparse or transform sparse target scene, the random nose radar based on CS can get high accuracy image by collecting far less amount of echo data than conventional noise radar does. Finally, in this paper, the conclusions are all demonstrated by simulation experiments.
Recent theory of Compressed Sensing (CS) suggests that exact recovery of an unknown sparse signal can be achieved from few measurements with overwhelming probability. In this paper, CS technology is combined with random noise radar and the concept of random noise radar is proposed based on CS. The block diagram of the radar system is presented. Detailed analysis show that the sensing matrix of the random noise radar based on CS exerts good Restricted Isometry Property (RIP). Given a sparse or transform sparse target scene, the random nose radar based on CS can get high accuracy image by collecting far less amount of echo data than conventional noise radar does. Finally, in this paper, the conclusions are all demonstrated by simulation experiments.
2011, 33(3): 677-683.
doi: 10.3724/SP.J.1146.2010.00532
Abstract:
Orthogonal Frequency-Division Multiplexing (OFDM) phase-coded radar has many prominent properties. However, there are some technical challenges on engineering realization, one of which is that instantaneous bandwidth is equal to the total bandwidth and large bandwidth leads to high requirement of the radar receiving technique. Aiming at this problem, a new radar signal named OFDM Phase-Coded Stepped-Frequency (OFDM-PCSF) signal is proposed. Several OFDM Phase-Coded (OFDM-PC) pulses with small bandwidth construct a pulse burst to synthesize large bandwidth, using stepped-frequency carriers. Based on deriving the ambiguity function of the new radar signal, the paper analyzes mainly the high range resolution and Doppler property. A conclusion is drawn that OFDM-PCSF signal can achieve high range resolution and the Doppler sensitivity is between the OFDM-PC pulse and the stepped-frequency signal.
Orthogonal Frequency-Division Multiplexing (OFDM) phase-coded radar has many prominent properties. However, there are some technical challenges on engineering realization, one of which is that instantaneous bandwidth is equal to the total bandwidth and large bandwidth leads to high requirement of the radar receiving technique. Aiming at this problem, a new radar signal named OFDM Phase-Coded Stepped-Frequency (OFDM-PCSF) signal is proposed. Several OFDM Phase-Coded (OFDM-PC) pulses with small bandwidth construct a pulse burst to synthesize large bandwidth, using stepped-frequency carriers. Based on deriving the ambiguity function of the new radar signal, the paper analyzes mainly the high range resolution and Doppler property. A conclusion is drawn that OFDM-PCSF signal can achieve high range resolution and the Doppler sensitivity is between the OFDM-PC pulse and the stepped-frequency signal.
2011, 33(3): 684-689.
doi: 10.3724/SP.J.1146.2010.00498
Abstract:
This paper presents two efficient algorithms for small squint and large squint mode Synthetic Aperture Radar (SAR) raw data simulation. One is based on SCaled Fourier Transform (SCFT) and the other is based on time-domain integration along range dimension. By SCFT the traditional frequency-domain algorithm with two-dimensional FFT is extended to small squint mode SAR. The algorithm employs SCFT to replace interpolation. The method improves both the computational efficiency and the simulation accuracy. Moreover, the proposed algorithm with time-domain integration along range dimension is applicable to large squint mode SAR. Compared with conventional time-domain technique, it is more efficient while still accurate. Simulation results demonstrate the validity of the two proposed algorithms.
This paper presents two efficient algorithms for small squint and large squint mode Synthetic Aperture Radar (SAR) raw data simulation. One is based on SCaled Fourier Transform (SCFT) and the other is based on time-domain integration along range dimension. By SCFT the traditional frequency-domain algorithm with two-dimensional FFT is extended to small squint mode SAR. The algorithm employs SCFT to replace interpolation. The method improves both the computational efficiency and the simulation accuracy. Moreover, the proposed algorithm with time-domain integration along range dimension is applicable to large squint mode SAR. Compared with conventional time-domain technique, it is more efficient while still accurate. Simulation results demonstrate the validity of the two proposed algorithms.
2011, 33(3): 690-695.
doi: 10.3724/SP.J.1146.2010.00555
Abstract:
In this paper, a SAR raw signal simulation algorithm is presented in a mixed time-frequency domain. By space-variant system transfer function along range, spectrum of raw signal is calculated precisely in range time domain. Then the complexity and phase precision are both analyzed. The result illustrates that it not only can improve the efficiency of simulation with high precision, but also can easily introduce motion error model in time domain. Finally several simulation experiments for point target and extended scene are provided. The results prove the validity of the proposed algorithm.
In this paper, a SAR raw signal simulation algorithm is presented in a mixed time-frequency domain. By space-variant system transfer function along range, spectrum of raw signal is calculated precisely in range time domain. Then the complexity and phase precision are both analyzed. The result illustrates that it not only can improve the efficiency of simulation with high precision, but also can easily introduce motion error model in time domain. Finally several simulation experiments for point target and extended scene are provided. The results prove the validity of the proposed algorithm.
2011, 33(3): 696-700.
doi: 10.3724/SP.J.1146.2010.00576
Abstract:
Adaptive detection for distributed target and multiple point targets in non-homogeneous environments is studied in this paper, where it is assumed that the covariance matrix of the secondary data follows inverse Wishart distribution conditioned on that of the primary data with its expectation proportional to it. The Maximum Likelihood Estimator (MLE) of the covariance matrix of the primary data, scale factor and target amplitude are firstly given and subsequently a detector is proposed based on Bayesian theory and Generalized Likelihood Ratio Test (GLRT) decision rule. The detector is coincident with the Adaptive Coherence Estimator (ACE) when the target exists in one range bin and it is consistent with the Generalized Adaptive Subspace Detector (GASD) when target extends more than one range bin. However, what makes it different is that the ACE and GASD are both based on unknown deterministic covariance matrix. Additionally, the detector has Constant False Alarm Rate (CFAR) and bears good performance.
Adaptive detection for distributed target and multiple point targets in non-homogeneous environments is studied in this paper, where it is assumed that the covariance matrix of the secondary data follows inverse Wishart distribution conditioned on that of the primary data with its expectation proportional to it. The Maximum Likelihood Estimator (MLE) of the covariance matrix of the primary data, scale factor and target amplitude are firstly given and subsequently a detector is proposed based on Bayesian theory and Generalized Likelihood Ratio Test (GLRT) decision rule. The detector is coincident with the Adaptive Coherence Estimator (ACE) when the target exists in one range bin and it is consistent with the Generalized Adaptive Subspace Detector (GASD) when target extends more than one range bin. However, what makes it different is that the ACE and GASD are both based on unknown deterministic covariance matrix. Additionally, the detector has Constant False Alarm Rate (CFAR) and bears good performance.
2011, 33(3): 701-705.
doi: 10.3724/SP.J.1146.2010.00643
Abstract:
On the basis of the impulse Ultra Wide Band (UWB) sequential signal module and the Maximum Likelihood (ML) rule, the generalized Cramer-Rao Lower Bound (CRLB) for UWB vital signal parameter estimation is analyzed with the Fisher Information Matrix (FIM) and the Cramer-Rao matrix inequation. According to the equivalent time sampling principal, the improved CRLB formula of UWB vital signal frequency detection is derived by adopting a sinusoidal displacement function superseding the vital jiggle signal. The simulation results show that the frequency precision of UWB radar vital signal detection increases with increasing the survey time, the impulse bandwidth and the system SNR. The heartbeat detection demands more rigorous conditions than that of the respiration detection.
On the basis of the impulse Ultra Wide Band (UWB) sequential signal module and the Maximum Likelihood (ML) rule, the generalized Cramer-Rao Lower Bound (CRLB) for UWB vital signal parameter estimation is analyzed with the Fisher Information Matrix (FIM) and the Cramer-Rao matrix inequation. According to the equivalent time sampling principal, the improved CRLB formula of UWB vital signal frequency detection is derived by adopting a sinusoidal displacement function superseding the vital jiggle signal. The simulation results show that the frequency precision of UWB radar vital signal detection increases with increasing the survey time, the impulse bandwidth and the system SNR. The heartbeat detection demands more rigorous conditions than that of the respiration detection.
2011, 33(3): 706-710.
doi: 10.3724/SP.J.1146.2010.00666
Abstract:
In this paper, an improved beam optimization algorithm for spaceborne SAR applications is presented to reduce the number of optimizing variables and the calculation time, compared with the traditional algorithm. This algorithm improves on the traditional genetic algorithm. In order to reduce the number of the optimizing parameters and expedite the optimization speed, the coefficients of a group of orthogonal base functions are set as the optimizing variables. This algorithm has been widely used in many projects and results with high performance are obtained.
In this paper, an improved beam optimization algorithm for spaceborne SAR applications is presented to reduce the number of optimizing variables and the calculation time, compared with the traditional algorithm. This algorithm improves on the traditional genetic algorithm. In order to reduce the number of the optimizing parameters and expedite the optimization speed, the coefficients of a group of orthogonal base functions are set as the optimizing variables. This algorithm has been widely used in many projects and results with high performance are obtained.
2011, 33(3): 711-716.
doi: 10.3724/SP.J.1146.2010.00493
Abstract:
In this paper, an evaluation method based on modified structure similarity of jamming effects on synthetic aperture radar is proposed. This method can not only make good use of structure similarity as juncture between the subjective and the objective evaluation methods, but also utilize the character of gradient modulus which matches with the human vision system's multichannel model, eventually, the modified evaluation index named GSSIM (Gradient Structural SIMilarity) is obtained by nonlinear combination. Simulation results show that GSSIM has an obvious advantage over traditional evaluation indexes, such as MSE, PSNR, Correlation and so on. Besides reflecting the influences of jamming on Region Of Interest (ROI) in the image, it can keep identical to Human Vision System (HVS), and furthermore, it improves the efficiency and accuracy of entire evaluation system.
In this paper, an evaluation method based on modified structure similarity of jamming effects on synthetic aperture radar is proposed. This method can not only make good use of structure similarity as juncture between the subjective and the objective evaluation methods, but also utilize the character of gradient modulus which matches with the human vision system's multichannel model, eventually, the modified evaluation index named GSSIM (Gradient Structural SIMilarity) is obtained by nonlinear combination. Simulation results show that GSSIM has an obvious advantage over traditional evaluation indexes, such as MSE, PSNR, Correlation and so on. Besides reflecting the influences of jamming on Region Of Interest (ROI) in the image, it can keep identical to Human Vision System (HVS), and furthermore, it improves the efficiency and accuracy of entire evaluation system.
2011, 33(3): 717-722.
doi: 10.3724/SP.J.1146.2010.00636
Abstract:
In order to meet the processing requirements of portable real-time full HD video compression, this paper proposes a novel macroblock-level parallel architecture based on 1-D source pixels based linear array, which overcomes the problem of massive amount of resources and large delay caused by 2-D arrays used in literatures. The proposed architecture is easy to extend and area-economical. Furthermore, towards the system bottlenecks, systolic cell and data memory organization, optimized structure are presented. Compared with the traditional architecture, the proposed architecture can achieve the improvements of speed and area at the same time. FPGA implementation results show that, LUTs is reduced by 43%, DFFs is reduced by 25%, BRAMs is reduced by 75%, and performance is increased by 32%.
In order to meet the processing requirements of portable real-time full HD video compression, this paper proposes a novel macroblock-level parallel architecture based on 1-D source pixels based linear array, which overcomes the problem of massive amount of resources and large delay caused by 2-D arrays used in literatures. The proposed architecture is easy to extend and area-economical. Furthermore, towards the system bottlenecks, systolic cell and data memory organization, optimized structure are presented. Compared with the traditional architecture, the proposed architecture can achieve the improvements of speed and area at the same time. FPGA implementation results show that, LUTs is reduced by 43%, DFFs is reduced by 25%, BRAMs is reduced by 75%, and performance is increased by 32%.
2011, 33(3): 723-728.
doi: 10.3724/SP.J.1146.2010.00463
Abstract:
This paper analyzes emphatically the read-write conflict mechanism of reconfigurable memory, and reveals the relations of address conflict, readout mapping and routing of memory under reconfigurable condition. Besides, the paper presents a bit identifying method for achieving the high-powered conflict-free reconfigurable memory. Buffering the writing operations and adding identifying bits for input data when the conflict occurs, the identifying bits use for controlling the data to input to memory core or output to memory. Comparing with another method, the experiment results of verifying in 0.13-m and 0.18-m mainstream CMOS technologies show obvious advantages: area decreases about 11%; speed increases about 21%. This technology has been applied into a homemade million-gate FPGA device, and testing results show it have achieved the conflict-free purpose.
This paper analyzes emphatically the read-write conflict mechanism of reconfigurable memory, and reveals the relations of address conflict, readout mapping and routing of memory under reconfigurable condition. Besides, the paper presents a bit identifying method for achieving the high-powered conflict-free reconfigurable memory. Buffering the writing operations and adding identifying bits for input data when the conflict occurs, the identifying bits use for controlling the data to input to memory core or output to memory. Comparing with another method, the experiment results of verifying in 0.13-m and 0.18-m mainstream CMOS technologies show obvious advantages: area decreases about 11%; speed increases about 21%. This technology has been applied into a homemade million-gate FPGA device, and testing results show it have achieved the conflict-free purpose.
2011, 33(3): 729-733.
doi: 10.3724/SP.J.1146.2010.00629
Abstract:
While current researches on terminal information model could not provide enough support for Ubiquitous Terminal Service (UTS) in respect of information, requirements and modeling method for management information in UTS are studied. According to the method, a generic management information model for UTS is established. The model could make up for the shortage of current terminal information model by adopting hierarchical domain, providing management information through device, network, service to customer level, and showing the relationship between those information. A realization mechanism for intelligence and individuation UTS is given with model-based reasoning. The modeling method and the mechanism are verified with a typical ubiquitous service. The results show that the information model can extract all kinds of managed resources and can be used as a basis to provide individualized UTS under heterogeneous terminal environments.
While current researches on terminal information model could not provide enough support for Ubiquitous Terminal Service (UTS) in respect of information, requirements and modeling method for management information in UTS are studied. According to the method, a generic management information model for UTS is established. The model could make up for the shortage of current terminal information model by adopting hierarchical domain, providing management information through device, network, service to customer level, and showing the relationship between those information. A realization mechanism for intelligence and individuation UTS is given with model-based reasoning. The modeling method and the mechanism are verified with a typical ubiquitous service. The results show that the information model can extract all kinds of managed resources and can be used as a basis to provide individualized UTS under heterogeneous terminal environments.
2011, 33(3): 734-738.
doi: 10.3724/SP.J.1146.2010.00675
Abstract:
A concurrent transmission scheme is proposed in this paper based on nodal SINR (Signal to Interference plus Noise Ratio) under fast and slow fading coexistence channel in Ad hoc networks. Based on the distribution of channel quality, a concurrent transmission model is given between different sources and destinations with non-cooperative game theory and Bayesian Nash Equilibrium. Then the relay mechanism is proposed to increase the concurrent transmission opportunity for hunger nodes whose channel qualities are under concurrent transmission threshold for a long time. Simulation results show that the proposed CTCG (Concurrent Transmission based on Channel quality with Game theory aid) model can greatly increase the chance of concurrent transmission, improve the system throughput and handle the hunger nodes transmission problems in Ad hoc networks.
A concurrent transmission scheme is proposed in this paper based on nodal SINR (Signal to Interference plus Noise Ratio) under fast and slow fading coexistence channel in Ad hoc networks. Based on the distribution of channel quality, a concurrent transmission model is given between different sources and destinations with non-cooperative game theory and Bayesian Nash Equilibrium. Then the relay mechanism is proposed to increase the concurrent transmission opportunity for hunger nodes whose channel qualities are under concurrent transmission threshold for a long time. Simulation results show that the proposed CTCG (Concurrent Transmission based on Channel quality with Game theory aid) model can greatly increase the chance of concurrent transmission, improve the system throughput and handle the hunger nodes transmission problems in Ad hoc networks.
2011, 33(3): 739-743.
doi: 10.3724/SP.J.1146.2010.00487
Abstract:
Non-Data-Aided (NDA) symbol synchronization for Orthogonal Frequency Division Multiplexing (OFDM) systems is studied in this paper. Firstly, a cost function, which is based on the power difference between adjacent subcarriers of OFDM system with constant modulus signaling, is proposed by assuming that the adjacent subcarriers have the same channel frequency responses. And a NDA symbol synchronization algorithm is proposed by minimizing the cost function. Secondly, two similar cost functions are proposed. The complexity and the influence of carrier frequency offset and channel noise on the proposed algorithm are analyzed too. Finally, the performance of proposed algorithm is analyzed by computer simulation with different cost functions and different carrier frequency offset. The simulation results show that the proposed algorithm outperforms generally obviously two others previously algorithms.
Non-Data-Aided (NDA) symbol synchronization for Orthogonal Frequency Division Multiplexing (OFDM) systems is studied in this paper. Firstly, a cost function, which is based on the power difference between adjacent subcarriers of OFDM system with constant modulus signaling, is proposed by assuming that the adjacent subcarriers have the same channel frequency responses. And a NDA symbol synchronization algorithm is proposed by minimizing the cost function. Secondly, two similar cost functions are proposed. The complexity and the influence of carrier frequency offset and channel noise on the proposed algorithm are analyzed too. Finally, the performance of proposed algorithm is analyzed by computer simulation with different cost functions and different carrier frequency offset. The simulation results show that the proposed algorithm outperforms generally obviously two others previously algorithms.
2011, 33(3): 744-748.
doi: 10.3724/SP.J.1146.2010.00399
Abstract:
A novel space mapping algorithm with high convergence is presented that improves the parameters mapping from surrogate model to fine model. By adding the process of coarse model parameter selection, it avoids false convergence in the optimization of surrogate model and speeds up the approximation between fine model and design object. No extra fine model evaluation is necessary in the parameter selection process, the optimization efficiency is improved. In this paper, a hairpin filter is designed and is compared with previous implicit space mapping algorithm, the results are better than the design specifications. The new algorithm is verified faster and more efficient.
A novel space mapping algorithm with high convergence is presented that improves the parameters mapping from surrogate model to fine model. By adding the process of coarse model parameter selection, it avoids false convergence in the optimization of surrogate model and speeds up the approximation between fine model and design object. No extra fine model evaluation is necessary in the parameter selection process, the optimization efficiency is improved. In this paper, a hairpin filter is designed and is compared with previous implicit space mapping algorithm, the results are better than the design specifications. The new algorithm is verified faster and more efficient.
2011, 33(3): 749-753.
doi: 10.3724/SP.J.1146.2010.00587
Abstract:
A novel design method for hardware-efficient digital interpolation filter applied to stereo audio Sigma- Delta Digital-to-Analog Converter (- DAC) is proposed in this paper. The method proclaims a new structure of multiplexing the interpolation filter by the left and right channel. The reorder technique is presented to keep the two channels being completely synchronization after multiplexing. The design is fabricated on TSMC 0.18m 1.8 V/3.3 V 1P5M CMOS process. The measurement results show that the DAC achieves 106 dB SNR over the 20 kHz audio band. The digital part of chip occupies only 0.198 mm2 and dissipates only 0.65 mW power. This design method benefits low chip area and power consumption and leaves much more design margin to the analog part of the - DAC, which provides important significance in mixed-signal system design.
A novel design method for hardware-efficient digital interpolation filter applied to stereo audio Sigma- Delta Digital-to-Analog Converter (- DAC) is proposed in this paper. The method proclaims a new structure of multiplexing the interpolation filter by the left and right channel. The reorder technique is presented to keep the two channels being completely synchronization after multiplexing. The design is fabricated on TSMC 0.18m 1.8 V/3.3 V 1P5M CMOS process. The measurement results show that the DAC achieves 106 dB SNR over the 20 kHz audio band. The digital part of chip occupies only 0.198 mm2 and dissipates only 0.65 mW power. This design method benefits low chip area and power consumption and leaves much more design margin to the analog part of the - DAC, which provides important significance in mixed-signal system design.
2011, 33(3): 754-757.
doi: 10.3724/SP.J.1146.2010.00661
Abstract:
In this paper, the Asymptotic Waveform Evaluation (AWE) technique is applied to study electromagnetic scattering analysis of Double-NeGative (DNG) medium. The PMCHWT equation of the DNG is deduced based on its constitutive relationship. And the surface currents and Radar Cross Section (RCS) at a single frequency point is computed; In order to achieve high-order derivation work, impedance matrix elements are managed. Then the AWE technique is applied to obtain broadband RCS frequency response of the DNG. A good agreement can be seen between AWE and the exact solution. The computational efficiency is improved significantly.
In this paper, the Asymptotic Waveform Evaluation (AWE) technique is applied to study electromagnetic scattering analysis of Double-NeGative (DNG) medium. The PMCHWT equation of the DNG is deduced based on its constitutive relationship. And the surface currents and Radar Cross Section (RCS) at a single frequency point is computed; In order to achieve high-order derivation work, impedance matrix elements are managed. Then the AWE technique is applied to obtain broadband RCS frequency response of the DNG. A good agreement can be seen between AWE and the exact solution. The computational efficiency is improved significantly.
2011, 33(3): 758-762.
doi: 10.3724/SP.J.1146.2010.00519
Abstract:
The problems, which can not be calculated due to the insufficient of memory, can be solved with out-of- core solving method, but it takes too longer time because the speed limit of the data reading/writing on the disk. To solve the above problem, parallel out-of-core solving method is used. In order to use the RAM sufficiently and reduce the reading/writing time, the matrix is eliminated by looping over blocks in parallel, so the solving speed is accelerated. The bistatic RCS of a PEC cube, a PEC union and a plane model are calculated, respectively. Parallel block out-of-core solver, which is proposed in this paper, is compared with usual parallel out-of-core solver and parallel in-core solver. The results indicate that the method in this paper can effectively solve the scattering problems of electrically large objects, and the calculation precision is not lost.
The problems, which can not be calculated due to the insufficient of memory, can be solved with out-of- core solving method, but it takes too longer time because the speed limit of the data reading/writing on the disk. To solve the above problem, parallel out-of-core solving method is used. In order to use the RAM sufficiently and reduce the reading/writing time, the matrix is eliminated by looping over blocks in parallel, so the solving speed is accelerated. The bistatic RCS of a PEC cube, a PEC union and a plane model are calculated, respectively. Parallel block out-of-core solver, which is proposed in this paper, is compared with usual parallel out-of-core solver and parallel in-core solver. The results indicate that the method in this paper can effectively solve the scattering problems of electrically large objects, and the calculation precision is not lost.
