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2006 Vol. 28, No. 10
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2006, 28(10): 1761-1765.
Abstract:
The research of source number detection is still open and challenge issue in array signal processing. The accurate estimation may be very essential to those high resolution direction finding algorithms. However, the traditional methods are sensitive to different noise fields and the performances of them are degraded in short snapshots. To overcome these drawbacks, an effective, accurate, robust detection method of the number of sources is proposed using the fuzzy-c-means clustering algorithm. The simulation results with two noise fields demonstrate the effectiveness and robustness of the proposed scheme.
The research of source number detection is still open and challenge issue in array signal processing. The accurate estimation may be very essential to those high resolution direction finding algorithms. However, the traditional methods are sensitive to different noise fields and the performances of them are degraded in short snapshots. To overcome these drawbacks, an effective, accurate, robust detection method of the number of sources is proposed using the fuzzy-c-means clustering algorithm. The simulation results with two noise fields demonstrate the effectiveness and robustness of the proposed scheme.
2006, 28(10): 1766-1769.
Abstract:
A new algorithm to estimate jointly the Direction-Of-Arrival (DOA) and range of near field sources is presented. Firstly, the whiten matrix is constructed by use of the second order statistics, and then the array steering matrix of near field sources is estimated by use of joint diagonalization of the array cumulant matrices, which exploits the structural information of the higher order statistics of the data received by the array. Thus the DOA and range can be estimated from the array steering vectors simultaneously. Compared with the higher-order ESPRIT method, the new algorithm can improve the efficiency of elements. In addition, it does not need any operation of parameters pairing. Its good performance is verified by computer simulation results.
A new algorithm to estimate jointly the Direction-Of-Arrival (DOA) and range of near field sources is presented. Firstly, the whiten matrix is constructed by use of the second order statistics, and then the array steering matrix of near field sources is estimated by use of joint diagonalization of the array cumulant matrices, which exploits the structural information of the higher order statistics of the data received by the array. Thus the DOA and range can be estimated from the array steering vectors simultaneously. Compared with the higher-order ESPRIT method, the new algorithm can improve the efficiency of elements. In addition, it does not need any operation of parameters pairing. Its good performance is verified by computer simulation results.
2006, 28(10): 1770-1773.
Abstract:
Based on the characteristics of cyclostationarity of Continuous Phase Modulation (CPM) signals with integer and half integer modulation index, a novel method of detecting CPM signals under the condition of unknown code sequence, carrier frequency, chip width and peak frequency deviation is presented in this paper. This method is an improvement of the traditional cyclic spectral analyzer; as well, its high detection performance is proved by the computer simulations.
Based on the characteristics of cyclostationarity of Continuous Phase Modulation (CPM) signals with integer and half integer modulation index, a novel method of detecting CPM signals under the condition of unknown code sequence, carrier frequency, chip width and peak frequency deviation is presented in this paper. This method is an improvement of the traditional cyclic spectral analyzer; as well, its high detection performance is proved by the computer simulations.
2006, 28(10): 1774-1777.
Abstract:
Based on symbol dynamics in 1-D piecewise linear mapping chaotic systems, an arithmetic method processing chaotic signals is studied in the paper, including addition, subtraction and multiplication. The operational rules are calculated and proved according to a definition of the distance between two chaotic sequences. By computer simulation with convolution sum of FIR digital filter, the results show that the model is the same as traditional binary coding arithmetic, which can be used in chaotic signal processing systems.
Based on symbol dynamics in 1-D piecewise linear mapping chaotic systems, an arithmetic method processing chaotic signals is studied in the paper, including addition, subtraction and multiplication. The operational rules are calculated and proved according to a definition of the distance between two chaotic sequences. By computer simulation with convolution sum of FIR digital filter, the results show that the model is the same as traditional binary coding arithmetic, which can be used in chaotic signal processing systems.
2006, 28(10): 1778-1781.
Abstract:
Two methods of rapid code acquisition based on FFT are presented, one method is based on fractional multiple sampling rate convertor, and the other is based on decimation. To reduce hardware resource, two rapid code acquisition circuits utilizes duplicate design. Two designs applied parallel pipeline structure to improve the processing speed. Block floating-point arithmetic is used to enhance the dynamic range and computation accuracy. Two designs are implemented with a chip of FPGA respectively, simulation and measurement results show that the rapid code acquisition circuit based on fractional multiple sampling rate convertor costs more hardware resource, but can gain higher acquisition accuracy to be compared with the method based on decimation.
Two methods of rapid code acquisition based on FFT are presented, one method is based on fractional multiple sampling rate convertor, and the other is based on decimation. To reduce hardware resource, two rapid code acquisition circuits utilizes duplicate design. Two designs applied parallel pipeline structure to improve the processing speed. Block floating-point arithmetic is used to enhance the dynamic range and computation accuracy. Two designs are implemented with a chip of FPGA respectively, simulation and measurement results show that the rapid code acquisition circuit based on fractional multiple sampling rate convertor costs more hardware resource, but can gain higher acquisition accuracy to be compared with the method based on decimation.
2006, 28(10): 1782-1785.
Abstract:
Mutual information has been used as a similarity metric in medical image registration. The probabilities of mutual information may be estimated by normalization of the joint intensity histogram, which is obtained by binning the intensity pair of the overlapping parts of the reference image and the floating image. However, image interpolation would create new intensity pairs and may cause local maxima of mutual information. In this paper, local maxima of mutual information are analyzed using linear interpolation and near neighborhood interpolation for different resolution images. Analysis results show that mutual information contains less local maxima when linear interpolation is used, and contains local maxima when near neighborhood interpolation is used. Experiments show the validity of the results. All these results are benefit to multimodal medical image registration.
Mutual information has been used as a similarity metric in medical image registration. The probabilities of mutual information may be estimated by normalization of the joint intensity histogram, which is obtained by binning the intensity pair of the overlapping parts of the reference image and the floating image. However, image interpolation would create new intensity pairs and may cause local maxima of mutual information. In this paper, local maxima of mutual information are analyzed using linear interpolation and near neighborhood interpolation for different resolution images. Analysis results show that mutual information contains less local maxima when linear interpolation is used, and contains local maxima when near neighborhood interpolation is used. Experiments show the validity of the results. All these results are benefit to multimodal medical image registration.
2006, 28(10): 1786-1789.
Abstract:
An effective and robust speech feature extraction method based on pitch frequency and harmonic structure is proposed by means of short-time spectrum analysis of clear and noisy speech. Experimental results indicate that the new feature is relatively insensitive to Additive White Gaussian Noise (AWGN). Compared to conventional cepstrums, the new feature can give outstanding improvement for closed-set text-independent speaker identification under noisy environments corrupted by AWGN.
An effective and robust speech feature extraction method based on pitch frequency and harmonic structure is proposed by means of short-time spectrum analysis of clear and noisy speech. Experimental results indicate that the new feature is relatively insensitive to Additive White Gaussian Noise (AWGN). Compared to conventional cepstrums, the new feature can give outstanding improvement for closed-set text-independent speaker identification under noisy environments corrupted by AWGN.
2006, 28(10): 1790-1793.
Abstract:
To the predicate calculus on Intuitionistic Fuzzy Logic (IFL), a symmetric synthetic method for finding the truth of IFL propositions using membership and hesitancy degree is proposed on the basis of the hypothesis of an equilibrium state of supportability and opposability of neutral evidences indicated in the intuitionistic index. The fundamental operation rules on IFL propositions are presented. The investigation is with an emphasis on the techniques for conditional reasoning on IFL, including the implications, the conditions, the multiplications, and the multi-dimensions on IFL, etc. The related sets of mathematical formulas of inference compositional operations are derived. To the IFL reasoning with confidence factors, including those of the typical, the weighted, and the narrow senses, the effects of confidence factors spreading abroad in rules on those of conclusions are analyzed. The related formulas for finding the true conclusions are exposed.
To the predicate calculus on Intuitionistic Fuzzy Logic (IFL), a symmetric synthetic method for finding the truth of IFL propositions using membership and hesitancy degree is proposed on the basis of the hypothesis of an equilibrium state of supportability and opposability of neutral evidences indicated in the intuitionistic index. The fundamental operation rules on IFL propositions are presented. The investigation is with an emphasis on the techniques for conditional reasoning on IFL, including the implications, the conditions, the multiplications, and the multi-dimensions on IFL, etc. The related sets of mathematical formulas of inference compositional operations are derived. To the IFL reasoning with confidence factors, including those of the typical, the weighted, and the narrow senses, the effects of confidence factors spreading abroad in rules on those of conclusions are analyzed. The related formulas for finding the true conclusions are exposed.
2006, 28(10): 1794-1797.
Abstract:
Image fusion principles have been widely used in application of imaging remote sensing as an effective means of synergistic combination of information. Image fusion applied for target recognition should be modeling for each different task. A kind of fusion model for bridge automatic detection in multi-source remote sensing image is proposed in the paper, which is designed based on the character of multi-source data, bridge identity and the background feature in remote sensing images. The results of bridge automatic detection in real images of complex scene prove the models validity.
Image fusion principles have been widely used in application of imaging remote sensing as an effective means of synergistic combination of information. Image fusion applied for target recognition should be modeling for each different task. A kind of fusion model for bridge automatic detection in multi-source remote sensing image is proposed in the paper, which is designed based on the character of multi-source data, bridge identity and the background feature in remote sensing images. The results of bridge automatic detection in real images of complex scene prove the models validity.
2006, 28(10): 1798-1801.
Abstract:
In this paper, a technique for compressing Synthetic Aperture Radar(SAR) raw data using block lifting wavelet transform is considered. Due to the statistical properties of SAR signal, a proper subband bit allocation strategy is presented. At high bit rates and low bit rates, the uniform and non-uniform Lloyd-Max quantizer optimized for Gaussian statistics is respectively used to quantize the wavelet coefficients in order to get the optimum quantization gain. The performances achieved in terms of bit rate reduction and certain quality parameters have been evaluated. These show an increased performance in this method with respect to conventional methods.
In this paper, a technique for compressing Synthetic Aperture Radar(SAR) raw data using block lifting wavelet transform is considered. Due to the statistical properties of SAR signal, a proper subband bit allocation strategy is presented. At high bit rates and low bit rates, the uniform and non-uniform Lloyd-Max quantizer optimized for Gaussian statistics is respectively used to quantize the wavelet coefficients in order to get the optimum quantization gain. The performances achieved in terms of bit rate reduction and certain quality parameters have been evaluated. These show an increased performance in this method with respect to conventional methods.
2006, 28(10): 1802-1805.
Abstract:
A method fused by Extended Fractal (EF) feature and local contract feature is proposed for target detection in SAR image. The paper mainly discussed the size sensitivity behavior for the EF feature and the second-order statistics for the EF feature in various target/clutter models, and concluded that the feature is also invariant to negative scalar multiplication of the image in the sense that a deep target-sized shadow can also be detected as well as bright target-sized objects. While the CFAR method only using the local contract information is not symmetric, it has a high false alarm in the strong clutter environment. Fusion of the two features provides an even lower false alarm rate when the targets can be detected. Experiments with real data show the effective of the fusion method.
A method fused by Extended Fractal (EF) feature and local contract feature is proposed for target detection in SAR image. The paper mainly discussed the size sensitivity behavior for the EF feature and the second-order statistics for the EF feature in various target/clutter models, and concluded that the feature is also invariant to negative scalar multiplication of the image in the sense that a deep target-sized shadow can also be detected as well as bright target-sized objects. While the CFAR method only using the local contract information is not symmetric, it has a high false alarm in the strong clutter environment. Fusion of the two features provides an even lower false alarm rate when the targets can be detected. Experiments with real data show the effective of the fusion method.
2006, 28(10): 1806-1808.
Abstract:
Because of the multiple-beam scanning strategy in swath, the intrinsic periodic scalloping exists in ScanSAR, which affects the radiometric property of ScanSAR. Based on the character of ScanSAR, the mechanism and property are studied, radiometric error caused by scalloping and relation between Doppler centroid error and scalloping are quantificationally analyzed. The residual error after correction is also studied.
Because of the multiple-beam scanning strategy in swath, the intrinsic periodic scalloping exists in ScanSAR, which affects the radiometric property of ScanSAR. Based on the character of ScanSAR, the mechanism and property are studied, radiometric error caused by scalloping and relation between Doppler centroid error and scalloping are quantificationally analyzed. The residual error after correction is also studied.
2006, 28(10): 1809-1811.
Abstract:
The active deception jamming is paid much attention in SAR ECM. So how to deal with the active deception jamming is a problem in SAR ECCM. This paper presents that InSAR can recognize the active deception jamming and suppress it. The interferometric phase graph is used to recognize the active deception jamming. The active deception jamming will make the interferometric phase graph disturbed.
The active deception jamming is paid much attention in SAR ECM. So how to deal with the active deception jamming is a problem in SAR ECCM. This paper presents that InSAR can recognize the active deception jamming and suppress it. The interferometric phase graph is used to recognize the active deception jamming. The active deception jamming will make the interferometric phase graph disturbed.
2006, 28(10): 1812-1816.
Abstract:
Wideband-high-resolution SAR background clutters affect the target detection and classification seriously. Aiming at SARs weakness , the paper puts forward a new matching jamming, which is time, frequency and Doppler fields multidimensional-matching-overcast similar clutters jamming. In the paper, generation of the correlated statistical clutter vectors using zero memory nonlinearity method is developed. Because of the traditional method of using digital frequency memorizer is inapplicable to wideband SAR jamming, the jamming theory based on the leading of parameters and narrowband signals pieceing together technology on wideband jamming realization is researched .Finally, through the Matlab emluator, the paper validates that the method is effectual to jam the wideband SAR.
Wideband-high-resolution SAR background clutters affect the target detection and classification seriously. Aiming at SARs weakness , the paper puts forward a new matching jamming, which is time, frequency and Doppler fields multidimensional-matching-overcast similar clutters jamming. In the paper, generation of the correlated statistical clutter vectors using zero memory nonlinearity method is developed. Because of the traditional method of using digital frequency memorizer is inapplicable to wideband SAR jamming, the jamming theory based on the leading of parameters and narrowband signals pieceing together technology on wideband jamming realization is researched .Finally, through the Matlab emluator, the paper validates that the method is effectual to jam the wideband SAR.
2006, 28(10): 1817-1819.
Abstract:
Firstly, the working principle of pseudo-random code phase-modulation fuze is described in the paper. The scheme of spot and deception jammer of pseudo-random code phase-modulation fuze is given. The circuit principle of each part and its hardware implemented circuit are presented. It includes mainly that demodulation of pseudo-random code phase-modulation signal ,recognition and reconstruction of demodulated code, modulation and transmission of interfered waveform .According to testing results of each part circuit, the designed principle is correct. The scheme is feasible.
Firstly, the working principle of pseudo-random code phase-modulation fuze is described in the paper. The scheme of spot and deception jammer of pseudo-random code phase-modulation fuze is given. The circuit principle of each part and its hardware implemented circuit are presented. It includes mainly that demodulation of pseudo-random code phase-modulation signal ,recognition and reconstruction of demodulated code, modulation and transmission of interfered waveform .According to testing results of each part circuit, the designed principle is correct. The scheme is feasible.
2006, 28(10): 1820-1826.
Abstract:
An audio watermarking scheme which embedded robust and fragile watermark at the same time in lifting wavelet domain is presented. Robust watermark is embedded in the low frequency range using mean quantization. It has great robustness and imperceptibility. Fragile watermark is embedded in the high frequency range by quantizating single coefficient, when the audio signal is tampered, the watermark information will change synchronously. So it can be used for audio content integrity verification. The watermark can be extracted without the original digital audio signal. Experimental results show that robust watermark is robust to many attacks, such as MP3 compression, low pass filtering, noise addition, requantization, resampling and so on. Fragile watermark is very sensitive to these attacks.
An audio watermarking scheme which embedded robust and fragile watermark at the same time in lifting wavelet domain is presented. Robust watermark is embedded in the low frequency range using mean quantization. It has great robustness and imperceptibility. Fragile watermark is embedded in the high frequency range by quantizating single coefficient, when the audio signal is tampered, the watermark information will change synchronously. So it can be used for audio content integrity verification. The watermark can be extracted without the original digital audio signal. Experimental results show that robust watermark is robust to many attacks, such as MP3 compression, low pass filtering, noise addition, requantization, resampling and so on. Fragile watermark is very sensitive to these attacks.
2006, 28(10): 1827-1830.
Abstract:
In Orthogonal Frequency-Division Multiplexing (OFDM) system, when using the partial power training sequence to synchronize, the received data signals will be seriously interfered by the training sequence. Due to the imperfect channel estimation, even if the training sequence separation technique is used, errors will also occur while using the inadequate knowledge of channel to perform the training sequence separation. This paper proposes an optimum method to suppress the interference from the training sequence to the data bearing OFDM symbols in frequency selective fading channels. A closed form formula for the optimized training sequence canceling factor is given by the theoretical analysis and its reasonability is verified by the simulation results.
In Orthogonal Frequency-Division Multiplexing (OFDM) system, when using the partial power training sequence to synchronize, the received data signals will be seriously interfered by the training sequence. Due to the imperfect channel estimation, even if the training sequence separation technique is used, errors will also occur while using the inadequate knowledge of channel to perform the training sequence separation. This paper proposes an optimum method to suppress the interference from the training sequence to the data bearing OFDM symbols in frequency selective fading channels. A closed form formula for the optimized training sequence canceling factor is given by the theoretical analysis and its reasonability is verified by the simulation results.
2006, 28(10): 1831-1836.
Abstract:
Noise threshold of Low Density Parity Check (LDPC) codes ensemble could be calculated by density evolution of the decoding messages. According to the threshold, performance of the decoding algorithm could be evaluated and degree distribution pairs of irregular LDPC codes also might be optimized. In this paper, for regular LDPC codes on Rice channel, Discrete Density Evolution(DDE) for BP,BP-based and offset BP-based decoding algorithm were compared on different quantization level and step. Furthermore, degree distribution pairs of the irregular LDPC codes were optimized on Rice channel, which was based on DDE for offset BP-based decoding algorithm, the corresponding threshold is also calculated. Finally, the Probability Mass Function (PMF) evolution curve of optimized irregular LDPC codes with code rate 1/2 on Rice channel is given.
Noise threshold of Low Density Parity Check (LDPC) codes ensemble could be calculated by density evolution of the decoding messages. According to the threshold, performance of the decoding algorithm could be evaluated and degree distribution pairs of irregular LDPC codes also might be optimized. In this paper, for regular LDPC codes on Rice channel, Discrete Density Evolution(DDE) for BP,BP-based and offset BP-based decoding algorithm were compared on different quantization level and step. Furthermore, degree distribution pairs of the irregular LDPC codes were optimized on Rice channel, which was based on DDE for offset BP-based decoding algorithm, the corresponding threshold is also calculated. Finally, the Probability Mass Function (PMF) evolution curve of optimized irregular LDPC codes with code rate 1/2 on Rice channel is given.
2006, 28(10): 1837-1841.
Abstract:
In this paper, a new approach is presented for optimizing the approximation of tanh rule based on Minimum Mean Square Error (MMSE) criterion under the Gaussian approximation. New concepts of anti-symmetric distribution and isomorphic generalized symmetric distribution are introduced. Under the isomorphic generalized symmetric distribution, several useful conclusions are drawn, by which a practical method for computing the optimal approximation is also presented. In comparison with the conventional approximation presented by Hagenauer, simulation results for several (3,6) regular Low-Density Parity-Check (LDPC) codes on the Additive White Gaussian Noise (AWGN) channel show that the approach can improve the decoding performance with a little increase in decoding complexity.
In this paper, a new approach is presented for optimizing the approximation of tanh rule based on Minimum Mean Square Error (MMSE) criterion under the Gaussian approximation. New concepts of anti-symmetric distribution and isomorphic generalized symmetric distribution are introduced. Under the isomorphic generalized symmetric distribution, several useful conclusions are drawn, by which a practical method for computing the optimal approximation is also presented. In comparison with the conventional approximation presented by Hagenauer, simulation results for several (3,6) regular Low-Density Parity-Check (LDPC) codes on the Additive White Gaussian Noise (AWGN) channel show that the approach can improve the decoding performance with a little increase in decoding complexity.
2006, 28(10): 1842-1845.
Abstract:
An adaptive NarrowBand Interference (NBI) suppression approach is proposed for DS-UWB systems. Based on the equivalence between the objective function optimization and linear equations, the proposed scheme translates the optimization model into linear equations and then performs adaptive filtering by employing an effective iterative method for linear equations, namely Conjugate Gradient (CG) algorithm. Theoretical analysis and simulation results show that, compared with the traditional NBI mitigation schemes, the proposed scheme can achieve a superior performance-to-cost ratio, and therefore can be considered as a compromised candidate for low cost, low power consumption and low complexity indoor UWB application scenarios.
An adaptive NarrowBand Interference (NBI) suppression approach is proposed for DS-UWB systems. Based on the equivalence between the objective function optimization and linear equations, the proposed scheme translates the optimization model into linear equations and then performs adaptive filtering by employing an effective iterative method for linear equations, namely Conjugate Gradient (CG) algorithm. Theoretical analysis and simulation results show that, compared with the traditional NBI mitigation schemes, the proposed scheme can achieve a superior performance-to-cost ratio, and therefore can be considered as a compromised candidate for low cost, low power consumption and low complexity indoor UWB application scenarios.
2006, 28(10): 1846-1850.
Abstract:
The stochastic bridge methods are employed in the current research for the modeling of UWB indoor multipath channel. Stochastic bridge processes are first introduced, and a physical fundament of UWB indoor multipath channel is analyzed. Then the distortion and the phase distribution of an UWB signal are investigated in details. A Brownian Bridge Model (BBM) for UWB indoor multipath channel is obtained by dividing the energy loss of an UWB signal into two parts: the propagation loss and the reflection loss, treating the UWB indoor multipaths as Brownian bridge process, and adopting two phase assumptions. Using the channel model to simulate a corridor environment of two glass doors with a metal grid inside, several characteristic parameters of UWB indoor multipath channel, such as amplitude responses, reflection index of every mulitipath, and power delay profiles (PDPs), are obtained, which are similar to the results from other experiments.
The stochastic bridge methods are employed in the current research for the modeling of UWB indoor multipath channel. Stochastic bridge processes are first introduced, and a physical fundament of UWB indoor multipath channel is analyzed. Then the distortion and the phase distribution of an UWB signal are investigated in details. A Brownian Bridge Model (BBM) for UWB indoor multipath channel is obtained by dividing the energy loss of an UWB signal into two parts: the propagation loss and the reflection loss, treating the UWB indoor multipaths as Brownian bridge process, and adopting two phase assumptions. Using the channel model to simulate a corridor environment of two glass doors with a metal grid inside, several characteristic parameters of UWB indoor multipath channel, such as amplitude responses, reflection index of every mulitipath, and power delay profiles (PDPs), are obtained, which are similar to the results from other experiments.
2006, 28(10): 1851-1853.
Abstract:
This paper presents a methodology to accurately predict link error performance based on capacity equivalence for a wide variety of channels. A metric based on Shannons channel capacity is introduced and combined with a new penalty factor Q relating to channel fading rate. And a new segment equivalent method is also presented to make use of the information of each slot in the prediction. This method requires a Q look-up formula and a reference AWGN performance curve per channel code rate and modulation. Simulation results show that this method provides a good prediction performance for different fading rate channels. Here is an example of Turbo code performance prediction, it is convenient to apply to other link-level cases.
This paper presents a methodology to accurately predict link error performance based on capacity equivalence for a wide variety of channels. A metric based on Shannons channel capacity is introduced and combined with a new penalty factor Q relating to channel fading rate. And a new segment equivalent method is also presented to make use of the information of each slot in the prediction. This method requires a Q look-up formula and a reference AWGN performance curve per channel code rate and modulation. Simulation results show that this method provides a good prediction performance for different fading rate channels. Here is an example of Turbo code performance prediction, it is convenient to apply to other link-level cases.
2006, 28(10): 1854-1857.
Abstract:
A novel frequency offset estimation algorithm for Orthogonal Frequency Division Multiplexing(OFDM) signals transmitted over frequency-selective channels is analyzed. The algorithm is discussed with channel zeros and arbitrarily assignment of null-subcarriers. The effect of distribution of null subcarriers and channel zeros is discussed. An adaptive assignment of null-subcarriers scheme is proposed. The proposed algorithm performs significantly better than the already existing methods.
A novel frequency offset estimation algorithm for Orthogonal Frequency Division Multiplexing(OFDM) signals transmitted over frequency-selective channels is analyzed. The algorithm is discussed with channel zeros and arbitrarily assignment of null-subcarriers. The effect of distribution of null subcarriers and channel zeros is discussed. An adaptive assignment of null-subcarriers scheme is proposed. The proposed algorithm performs significantly better than the already existing methods.
2006, 28(10): 1858-1861.
Abstract:
A novel multi-rate MB-OFDM ultra-wide band (UWB) system is proposed, in which users are distinguished from their unique time-frequency codes (TFC). Also an adaptive TFC allocation algorithm is given to minimize total transmitting power with the constraint of the minimal data rate requirement of each accessed user. Theoretical analysis and experimental results show that the proposed system and allocation algorithm are able to increase system access capacity of multi-rate users and save power effectively, which is just an UWB system needed.
A novel multi-rate MB-OFDM ultra-wide band (UWB) system is proposed, in which users are distinguished from their unique time-frequency codes (TFC). Also an adaptive TFC allocation algorithm is given to minimize total transmitting power with the constraint of the minimal data rate requirement of each accessed user. Theoretical analysis and experimental results show that the proposed system and allocation algorithm are able to increase system access capacity of multi-rate users and save power effectively, which is just an UWB system needed.
2006, 28(10): 1862-1865.
Abstract:
In this paper, a novel adaptive Interference Cancellation Decision Feedback Equalization algorithm based on Recursive Least Squares (RLS-IC-DFE) is proposed for Multi-Input Multi-Output (MIMO) wireless communication systems under frequency selective with time variation environment. This algorithm changes the equalizer of each sub-stream to an equal new longer equalizer, and takes the sub-streams that have been detected as the new input parameters, then uses RLS algorithm to update the parameters of the new equalizer. Simulation results show that the new adaptive RLS-IC-DFE equalizer can adaptively track the variation of wireless channel and save the overhead of training sequence. At the same time, the proposed scheme can provide the better Symbol Error Rate (SER) performance than the existed RLS-DFE algorithm.
In this paper, a novel adaptive Interference Cancellation Decision Feedback Equalization algorithm based on Recursive Least Squares (RLS-IC-DFE) is proposed for Multi-Input Multi-Output (MIMO) wireless communication systems under frequency selective with time variation environment. This algorithm changes the equalizer of each sub-stream to an equal new longer equalizer, and takes the sub-streams that have been detected as the new input parameters, then uses RLS algorithm to update the parameters of the new equalizer. Simulation results show that the new adaptive RLS-IC-DFE equalizer can adaptively track the variation of wireless channel and save the overhead of training sequence. At the same time, the proposed scheme can provide the better Symbol Error Rate (SER) performance than the existed RLS-DFE algorithm.
2006, 28(10): 1866-1869.
Abstract:
Clipping is usually applied to decrease the high peak-to-average power ratio caused by OFDM with interference both inside and outside the signal bandwidth. To resolve this problem, an iterative estimation and cancellation of clipping non-linear distortion scheme is proposed. This paper presents that the performance of estimation and cancellation of clipping non-linear is better than that of clipping noise. The method of iterative estimation and cancellation of clipping non-linear distortion can resume the signal before clipping perfectly with the ideal a priori information. However, if receiver only estimate and cancel the clipping noise the signal will still be influenced by the attenuation caused by clipping. Analysis and simulation results prove the conclusion. And it is shown by numerical simulation results that system performance can be improved evidently. When the clipping threshold is 1.2, the performance is improved about 2 dB with only one iterative estimation and cancellation.
Clipping is usually applied to decrease the high peak-to-average power ratio caused by OFDM with interference both inside and outside the signal bandwidth. To resolve this problem, an iterative estimation and cancellation of clipping non-linear distortion scheme is proposed. This paper presents that the performance of estimation and cancellation of clipping non-linear is better than that of clipping noise. The method of iterative estimation and cancellation of clipping non-linear distortion can resume the signal before clipping perfectly with the ideal a priori information. However, if receiver only estimate and cancel the clipping noise the signal will still be influenced by the attenuation caused by clipping. Analysis and simulation results prove the conclusion. And it is shown by numerical simulation results that system performance can be improved evidently. When the clipping threshold is 1.2, the performance is improved about 2 dB with only one iterative estimation and cancellation.
2006, 28(10): 1870-1873.
Abstract:
In this paper the concept of random permutation table is presented from F table in Skipjack block encryption. The probabilities and the expected values of closed state evolutive ring numbers and the average length of state evolutive rings are studied and their closed forms used in computation are given. For quick computation their recurrence forms are obtained. The theoretical results are proved experimentally by numerical simulation.
In this paper the concept of random permutation table is presented from F table in Skipjack block encryption. The probabilities and the expected values of closed state evolutive ring numbers and the average length of state evolutive rings are studied and their closed forms used in computation are given. For quick computation their recurrence forms are obtained. The theoretical results are proved experimentally by numerical simulation.
2006, 28(10): 1874-1878.
Abstract:
Intra-prediction is one of the new techniques adopted by H.264. Compared with the previous video coding standards, H.264 improves coding performance greatly. However, the computation load of H.264 video coding increases drastically. This paper investigates improvement of encoding speed for H.264 with special focus on fast intra prediction mode selection. Some experimental analyses indicate that the luminance values of the reference pixels for each 44 luminance block are commonly similar, and in that case, the prediction blocks of the nine prediction modes are also similar. According to this feature of 44 luminance block, a fast mode selection algorithm for intra prediction is proposed. Experimental results show the proposed scheme is very effective. Compared with JM92 in H.264 encoder, it reduces 46% encoding time while maintaining the PSNR and bit rate.
Intra-prediction is one of the new techniques adopted by H.264. Compared with the previous video coding standards, H.264 improves coding performance greatly. However, the computation load of H.264 video coding increases drastically. This paper investigates improvement of encoding speed for H.264 with special focus on fast intra prediction mode selection. Some experimental analyses indicate that the luminance values of the reference pixels for each 44 luminance block are commonly similar, and in that case, the prediction blocks of the nine prediction modes are also similar. According to this feature of 44 luminance block, a fast mode selection algorithm for intra prediction is proposed. Experimental results show the proposed scheme is very effective. Compared with JM92 in H.264 encoder, it reduces 46% encoding time while maintaining the PSNR and bit rate.
2006, 28(10): 1879-1882.
Abstract:
It is very common that the packets may be lost over IP networks during transmission. The scheme proposed in this paper involves a novel erasure correcting code, a packet sending order and error concealment method. The [9,5,3] erasure correcting code in this paper has excellent lost recovering capability, linear encoding and decoding time and is easily constructed. The packetization method increases the capability of error resilience against the burst packet loss. The error concealment tool FMO of H.264 is used to deal with the video information packet that can not be recovered.
It is very common that the packets may be lost over IP networks during transmission. The scheme proposed in this paper involves a novel erasure correcting code, a packet sending order and error concealment method. The [9,5,3] erasure correcting code in this paper has excellent lost recovering capability, linear encoding and decoding time and is easily constructed. The packetization method increases the capability of error resilience against the burst packet loss. The error concealment tool FMO of H.264 is used to deal with the video information packet that can not be recovered.
2006, 28(10): 1883-1887.
Abstract:
Interframe video coding mode decision algorithm is one of the most complex part in H.264 encoder. In this paper, the theory of variable block-size motion compensation in H.264 is given and the best mode statistical law of inter-frame video coding is analyzed at first. Then a novel fast mode decision algorithm based on prior detection is presented. The results of simulation test show that the proposed fast mode decision strategy can highly improve the efficiency of real time H.264 encoder while maintaining video coding quality.
Interframe video coding mode decision algorithm is one of the most complex part in H.264 encoder. In this paper, the theory of variable block-size motion compensation in H.264 is given and the best mode statistical law of inter-frame video coding is analyzed at first. Then a novel fast mode decision algorithm based on prior detection is presented. The results of simulation test show that the proposed fast mode decision strategy can highly improve the efficiency of real time H.264 encoder while maintaining video coding quality.
2006, 28(10): 1888-1891.
Abstract:
During transmitting encoded digital video sequences over noisy communication channels, the information of the images will be lost. An error concealment method based on robust optical flow is proposed, as a post-processing tool at the decoder side to solve this problem. The property of optical flow technique on efficiently obtaining motion estimation is used to recover the lost block in pixel-wise manner. This processing not only avoids the image blurring, but also reduces the blocking effect. In the estimation of optical flow, the relation between data conservation term and spatial coherence term of the objective function is adaptively adjusted. In order to increase the robustness, Lorentzian function is used to construct the energy function. Simulation results show that the proposed method can recover the higher quality image on both subjective visual evaluation and objective numerical metrics, comparing to the existing error concealment methods.
During transmitting encoded digital video sequences over noisy communication channels, the information of the images will be lost. An error concealment method based on robust optical flow is proposed, as a post-processing tool at the decoder side to solve this problem. The property of optical flow technique on efficiently obtaining motion estimation is used to recover the lost block in pixel-wise manner. This processing not only avoids the image blurring, but also reduces the blocking effect. In the estimation of optical flow, the relation between data conservation term and spatial coherence term of the objective function is adaptively adjusted. In order to increase the robustness, Lorentzian function is used to construct the energy function. Simulation results show that the proposed method can recover the higher quality image on both subjective visual evaluation and objective numerical metrics, comparing to the existing error concealment methods.
2006, 28(10): 1892-1896.
Abstract:
This paper investigates the outage performance of the cooperative diversity systems for multi-hop wireless networks over Nakagami fading channels. Their closed-form expressions of the regenerative outage probability are derived, and the diversity orders are achieved at high Average Signal-to-Noise Ratio (ASNR) in terms of the single relaying node case and multiple relaying nodes case. The theoretical analysis and simulation results show that the cooperative systems can offer the full-route diversity at some given manners, and their diversity order is the sum of the full route diversities, not the sum of all cooperative nodes, however, the diversity order of each route is determined by the smaller one between that of the two hops.
This paper investigates the outage performance of the cooperative diversity systems for multi-hop wireless networks over Nakagami fading channels. Their closed-form expressions of the regenerative outage probability are derived, and the diversity orders are achieved at high Average Signal-to-Noise Ratio (ASNR) in terms of the single relaying node case and multiple relaying nodes case. The theoretical analysis and simulation results show that the cooperative systems can offer the full-route diversity at some given manners, and their diversity order is the sum of the full route diversities, not the sum of all cooperative nodes, however, the diversity order of each route is determined by the smaller one between that of the two hops.
2006, 28(10): 1897-1901.
Abstract:
Threaded Algebraic Space Time (TAST) code achieves the full diversity gain without the loss of code rate, and fits the high-rate transmission. In this paper the Zero-Forcing (ZF) detections performance of the full-rate full-diversity TAST code is analyzed and compared with VBLAST. Theoretical analysis and simulation both show that the TASTs ZF detection performance is better than the VBLASTs, but their ZF-ordered successive interference cancellation (ZFOSIC) performance is alternated.
Threaded Algebraic Space Time (TAST) code achieves the full diversity gain without the loss of code rate, and fits the high-rate transmission. In this paper the Zero-Forcing (ZF) detections performance of the full-rate full-diversity TAST code is analyzed and compared with VBLAST. Theoretical analysis and simulation both show that the TASTs ZF detection performance is better than the VBLASTs, but their ZF-ordered successive interference cancellation (ZFOSIC) performance is alternated.
2006, 28(10): 1902-1906.
Abstract:
This paper presents an approach for modeling and solving the problems of intelligent fault identification and alarm correlation in large telecommunication networks. The network is initially divided into its constituting sub-networks. Different correlation technique is utilized in each sub-network according its characteristics. And the fault propagation model is used to model the functional relationship among the sub-networks. At same time, the paper also presents a distributed framework based on CORBA in alarm correlation. Finally the realization and performance of alarm correlation are discussed in SDH over DWDM systems. The experimentation has proved that the fault diagnosis efficiency is prompted by the distributed alarm correlation systems.
This paper presents an approach for modeling and solving the problems of intelligent fault identification and alarm correlation in large telecommunication networks. The network is initially divided into its constituting sub-networks. Different correlation technique is utilized in each sub-network according its characteristics. And the fault propagation model is used to model the functional relationship among the sub-networks. At same time, the paper also presents a distributed framework based on CORBA in alarm correlation. Finally the realization and performance of alarm correlation are discussed in SDH over DWDM systems. The experimentation has proved that the fault diagnosis efficiency is prompted by the distributed alarm correlation systems.
2006, 28(10): 1907-1911.
Abstract:
A dynamic multi-rate routing scheme is presented. It can increase the throughput and decrease the ETE transmission delay of the Mobile Ad hoc NETworks (MANETs). The scheme divides routing function into two parts, the wide routing function and the local routing function. The local routing function, as an independent sub layer, takes charge in properly adding new forwarding nodes between the source-destination pair, by which every link in the resulting route can transmit in faster rate and the total channel occupancy time be reduced. The local routing function can be realized by the new LDSR (Local Dynamic Source Routing) protocol. Simulation result shows that the new multi-rate routing scheme outperforms traditional MANET routing protocols due to its better utilization of multi-rate support.
A dynamic multi-rate routing scheme is presented. It can increase the throughput and decrease the ETE transmission delay of the Mobile Ad hoc NETworks (MANETs). The scheme divides routing function into two parts, the wide routing function and the local routing function. The local routing function, as an independent sub layer, takes charge in properly adding new forwarding nodes between the source-destination pair, by which every link in the resulting route can transmit in faster rate and the total channel occupancy time be reduced. The local routing function can be realized by the new LDSR (Local Dynamic Source Routing) protocol. Simulation result shows that the new multi-rate routing scheme outperforms traditional MANET routing protocols due to its better utilization of multi-rate support.
2006, 28(10): 1912-1916.
Abstract:
There are four traffic classes in wireless multimedia network, including conversational class, streaming class, interactive class, and background class, while three of them are Variable Bit Rate (VBR) traffic except conversation class. It will fall into a dilemma if conventional resource allocation methods are adopted (especially for the bandwidth allocation methods). In this paper, a dynamic bandwidth allocation scheme is proposed for packet switched wireless multimedia networks. The scheme could guarantee users QoS, while the utility of resource could be improved. Using these models, the effects of the changeable QoS dynamic bandwidth allocation and optimization strategy are evaluated from both points of view of the networks and users. Simulation results are presented to demonstrate the performance of the proposed scheme in terms of system capacity, blocking probability, delay, practical transmission ratio of video traffic, and the Integrated Grade of Service (IGoS) of VBR traffic. Compared with the conventional scheme, the proposed scheme can greatly improve the system performance and resource utility.
There are four traffic classes in wireless multimedia network, including conversational class, streaming class, interactive class, and background class, while three of them are Variable Bit Rate (VBR) traffic except conversation class. It will fall into a dilemma if conventional resource allocation methods are adopted (especially for the bandwidth allocation methods). In this paper, a dynamic bandwidth allocation scheme is proposed for packet switched wireless multimedia networks. The scheme could guarantee users QoS, while the utility of resource could be improved. Using these models, the effects of the changeable QoS dynamic bandwidth allocation and optimization strategy are evaluated from both points of view of the networks and users. Simulation results are presented to demonstrate the performance of the proposed scheme in terms of system capacity, blocking probability, delay, practical transmission ratio of video traffic, and the Integrated Grade of Service (IGoS) of VBR traffic. Compared with the conventional scheme, the proposed scheme can greatly improve the system performance and resource utility.
2006, 28(10): 1917-1920.
Abstract:
This paper presents a topology aggregation algorithm for asymmetric networks, which can keep all the asymmetric topology information, so that topology information distortion can be reduced. The algorithm constructs three spanning tree aggregated topologies to include all the asymmetric information with small space complexity. Simulation results show the good practical performance of the proposed algorithm.
This paper presents a topology aggregation algorithm for asymmetric networks, which can keep all the asymmetric topology information, so that topology information distortion can be reduced. The algorithm constructs three spanning tree aggregated topologies to include all the asymmetric information with small space complexity. Simulation results show the good practical performance of the proposed algorithm.
2006, 28(10): 1921-1925.
Abstract:
IEEE 802.16 broadband wireless access system adopts TDMA (Time-Division Multiple Access) and contention-based reservation of resource in its uplink MAC layer. Thus there are contentions and collisions between SSs(Subscriber Stations), and the performance is inevitably deteriorated. A fast and efficient backoff algorithm DBC (Dynamical Backoff Control) is proposed to solve the problem. In DBC, by predicting the number of request messages in next uplink frame, BS controls the optimal backoff ranges dynamically. As a result, the successful rate of sending request messages in each frame is increased, the data throughput of MAC layer is promoted, and the mean access delay of SS is reduced. Simulation is conducted in OPNET to compare DBC with binary exponential backoff. Simulation results demonstrate that proposed DBC algorithm makes a great improvement in system performance.
IEEE 802.16 broadband wireless access system adopts TDMA (Time-Division Multiple Access) and contention-based reservation of resource in its uplink MAC layer. Thus there are contentions and collisions between SSs(Subscriber Stations), and the performance is inevitably deteriorated. A fast and efficient backoff algorithm DBC (Dynamical Backoff Control) is proposed to solve the problem. In DBC, by predicting the number of request messages in next uplink frame, BS controls the optimal backoff ranges dynamically. As a result, the successful rate of sending request messages in each frame is increased, the data throughput of MAC layer is promoted, and the mean access delay of SS is reduced. Simulation is conducted in OPNET to compare DBC with binary exponential backoff. Simulation results demonstrate that proposed DBC algorithm makes a great improvement in system performance.
2006, 28(10): 1926-1929.
Abstract:
Available bandwidth is one of the important network resources, but it difficult to measure in practice. In this paper, SSP(SRdeg and SRdet parameters), an active end-to-end available bandwidth estimation algorithm based on delay trend model, is proposed. Two parameters SRdeg and SRdetare designed which can indicate the network transmission performance changes. By calculating these parameters, the end system can adjust the transmission rate so that the available bandwidth can be estimated quickly as well as the network resources can be effectively used. The parameters are tested by NS2 simulation platform. The performance of SSP algorithm is compared with Pathload, a currently used tool on available bandwidth estimation. The simulation experiments show that the proposed algorithm SSP is more efficient and accurate than that of Pathload.
Available bandwidth is one of the important network resources, but it difficult to measure in practice. In this paper, SSP(SRdeg and SRdet parameters), an active end-to-end available bandwidth estimation algorithm based on delay trend model, is proposed. Two parameters SRdeg and SRdetare designed which can indicate the network transmission performance changes. By calculating these parameters, the end system can adjust the transmission rate so that the available bandwidth can be estimated quickly as well as the network resources can be effectively used. The parameters are tested by NS2 simulation platform. The performance of SSP algorithm is compared with Pathload, a currently used tool on available bandwidth estimation. The simulation experiments show that the proposed algorithm SSP is more efficient and accurate than that of Pathload.
2006, 28(10): 1930-1934.
Abstract:
It is important to maximize the saturated throughput of 802.11 DCF for fully utilizing wireless bandwidth. The saturated throughput of 802.11 DCF is related to minimum contention windows, maximum backoff stage and the contending nodes in the networks. Based on the analysis to this relationship, this paper induces a simple formula to calculate the optimized minimum contention windows for maximizing the saturated throughput of 802.11 DCF, and gives a self-adaptive contention nodes estimation algorithm, according to which and the simple formula, the optimized minimum contention windows is adapted dynamically. The accuracy of above formula and algorithm is valuated by simulation. The saturated throughput of improved 802.11 DCF and the saturated throughput of 802.11 DCF are compared in this paper. The simulation results prove that the above formula and algorithm are accurate and effective.
It is important to maximize the saturated throughput of 802.11 DCF for fully utilizing wireless bandwidth. The saturated throughput of 802.11 DCF is related to minimum contention windows, maximum backoff stage and the contending nodes in the networks. Based on the analysis to this relationship, this paper induces a simple formula to calculate the optimized minimum contention windows for maximizing the saturated throughput of 802.11 DCF, and gives a self-adaptive contention nodes estimation algorithm, according to which and the simple formula, the optimized minimum contention windows is adapted dynamically. The accuracy of above formula and algorithm is valuated by simulation. The saturated throughput of improved 802.11 DCF and the saturated throughput of 802.11 DCF are compared in this paper. The simulation results prove that the above formula and algorithm are accurate and effective.
2006, 28(10): 1935-1939.
Abstract:
QoS is one of the hot points among the network study fields. Currently , because of Low Speed Network (LSN) occupying a very big specific weight among the whole networks, how to provide the real-time services with QoS guarantee for the LSNs customers becomes an important research concern.. In this paper, a scheduling algorithm called Real time Compensation Deficit RoundRobin (RCDRR) according to the LSNs characteristics is proposed to be suitable for realtime packets transmition, and comparing the RCDRR algorithm with DRR algorithm by using the ns2 software. Experiments and simulation results show that RCDRR scheduling algorithm possesses good fairness,low complexity,and can reduce the queuing delay of realtime packets in LSN.
QoS is one of the hot points among the network study fields. Currently , because of Low Speed Network (LSN) occupying a very big specific weight among the whole networks, how to provide the real-time services with QoS guarantee for the LSNs customers becomes an important research concern.. In this paper, a scheduling algorithm called Real time Compensation Deficit RoundRobin (RCDRR) according to the LSNs characteristics is proposed to be suitable for realtime packets transmition, and comparing the RCDRR algorithm with DRR algorithm by using the ns2 software. Experiments and simulation results show that RCDRR scheduling algorithm possesses good fairness,low complexity,and can reduce the queuing delay of realtime packets in LSN.
2006, 28(10): 1940-1945.
Abstract:
Enhancing Active Queue Management (AQM) algorithms self-adapting and overcoming network delays poor effect are research emphases. After analyzing traditional PID control algorithms limitation, a novel active queue management algorithm for delay network based on Fuzzy Adaptive PID control and Gray-prediction (FAGPID) is proposed, which can achieve PID parameters on-line self-adapting by fuzzy control under the dynamic delay network circumstances. And, a gray-prediction algorithm is successfully introduced into feedback datas advanced prediction to compensate delay. Contrasted with traditional PID and FIGPID (Fuzzy Immue Gray-prediction PID) by simulations, FAGPID has equivalent performance to FIGPID and has better performance than traditional PID control. Both FAGPID and FIGPID can converge to queue size-setting value rapidly and stably, and get lesser packets loss rate, but FAGPIDs algorithm complexity is lower.
Enhancing Active Queue Management (AQM) algorithms self-adapting and overcoming network delays poor effect are research emphases. After analyzing traditional PID control algorithms limitation, a novel active queue management algorithm for delay network based on Fuzzy Adaptive PID control and Gray-prediction (FAGPID) is proposed, which can achieve PID parameters on-line self-adapting by fuzzy control under the dynamic delay network circumstances. And, a gray-prediction algorithm is successfully introduced into feedback datas advanced prediction to compensate delay. Contrasted with traditional PID and FIGPID (Fuzzy Immue Gray-prediction PID) by simulations, FAGPID has equivalent performance to FIGPID and has better performance than traditional PID control. Both FAGPID and FIGPID can converge to queue size-setting value rapidly and stably, and get lesser packets loss rate, but FAGPIDs algorithm complexity is lower.
2006, 28(10): 1946-1949.
Abstract:
The output signal model of optical fiber Surface Plasmon Resonance (SPR) sensing systems is presented in which the noise is proved as Gaussian distribution by adopting skewness and kurtosis test, so signal averaging method has been used and the stand deviation is decreased. Further, the estimated mean after signal averaging processing still includes some noise which has also been proved as Gaussian noise by using the same test method and linear estimate model is used to determine the resonant wavelength and the light intensity at the wavelength. The results show that both the wavelength and the normalized light intensity detection precisions are approximate to the ones of the used spectrometer. Finally, the optimization method on the data processing is discussed and the data processing work is decreased as 2% of the initial one by used the method, which is particularly adaptable to measure the sensing medium whose refractive index varies with time quickly.
The output signal model of optical fiber Surface Plasmon Resonance (SPR) sensing systems is presented in which the noise is proved as Gaussian distribution by adopting skewness and kurtosis test, so signal averaging method has been used and the stand deviation is decreased. Further, the estimated mean after signal averaging processing still includes some noise which has also been proved as Gaussian noise by using the same test method and linear estimate model is used to determine the resonant wavelength and the light intensity at the wavelength. The results show that both the wavelength and the normalized light intensity detection precisions are approximate to the ones of the used spectrometer. Finally, the optimization method on the data processing is discussed and the data processing work is decreased as 2% of the initial one by used the method, which is particularly adaptable to measure the sensing medium whose refractive index varies with time quickly.
2006, 28(10): 1950-1954.
Abstract:
Signal-adapted institute of filter banks are an important subject in the theory and applications of the multirate filter banks.Since the frequency responses match the statistics of the underlying signals very well， these filter banks achieve the larger subband coding gains. This paper investigates the design of two-band signal-adapted biorthogonal linear phase filter banks and gives the design algorithm, in particular, the method to determine the initial points (initial filter banks) with the optimal IIR biorthogonal filter banks that is easy to be obtained. The result of emulation indicates that the subband coding gains of the resulted filter banks are excess those of the optimal IIR paraunitary filter banks much, and comparing with the existing results the subband coding gains are markedly improved.
Signal-adapted institute of filter banks are an important subject in the theory and applications of the multirate filter banks.Since the frequency responses match the statistics of the underlying signals very well， these filter banks achieve the larger subband coding gains. This paper investigates the design of two-band signal-adapted biorthogonal linear phase filter banks and gives the design algorithm, in particular, the method to determine the initial points (initial filter banks) with the optimal IIR biorthogonal filter banks that is easy to be obtained. The result of emulation indicates that the subband coding gains of the resulted filter banks are excess those of the optimal IIR paraunitary filter banks much, and comparing with the existing results the subband coding gains are markedly improved.
2006, 28(10): 1955-1958.
Abstract:
Based on boost converter, a new mode named PSM is modeled and analyzed using space state average method. Some useful formulae such as output voltage ratio, relationship between modulation factor and load, conversion efficiency are given in this paper. The conclusion can be easily got that PSM is an available control mode with high efficiency, especially for converter with light loads. The simulation results are given by designing the control circuit with PSM characteristic.
Based on boost converter, a new mode named PSM is modeled and analyzed using space state average method. Some useful formulae such as output voltage ratio, relationship between modulation factor and load, conversion efficiency are given in this paper. The conclusion can be easily got that PSM is an available control mode with high efficiency, especially for converter with light loads. The simulation results are given by designing the control circuit with PSM characteristic.
2006, 28(10): 1959-1962.
Abstract:
The effect of track distribution on chip area is investigated in this paper. Several typical distributions in math (Gaussian, Sine and Trigonal) are introduced to realize FPGAs architectures with routing channel width varying randomly on software platform. These various kinds of FPGA architecture are made comparison to the traditional FPGA with uniform routing channel width. The key results are that the non-uniform routing architectures educed from the introduction of maths distribution have a better area efficient than the uniform ones without sacrificing the circuit speed. And the trend of routing channel width transformation is that in the center of the chip is the peak point, and from the center to the edges the channel width becomes narrow gradually.
The effect of track distribution on chip area is investigated in this paper. Several typical distributions in math (Gaussian, Sine and Trigonal) are introduced to realize FPGAs architectures with routing channel width varying randomly on software platform. These various kinds of FPGA architecture are made comparison to the traditional FPGA with uniform routing channel width. The key results are that the non-uniform routing architectures educed from the introduction of maths distribution have a better area efficient than the uniform ones without sacrificing the circuit speed. And the trend of routing channel width transformation is that in the center of the chip is the peak point, and from the center to the edges the channel width becomes narrow gradually.
2006, 28(10): 1963-1966.
Abstract:
Based on the conducted emission measurements for the power line , the measurement uncertainties which affect the Electro Magnetic Compatibility(EMC) test are analyzed. This paper investigates the type A and type B uncertainties and the systemic errors. The results show that the tiny difference of the test setup can bring much difference.
Based on the conducted emission measurements for the power line , the measurement uncertainties which affect the Electro Magnetic Compatibility(EMC) test are analyzed. This paper investigates the type A and type B uncertainties and the systemic errors. The results show that the tiny difference of the test setup can bring much difference.
2006, 28(10): 1967-1970.
Abstract:
Boundary Element Method(BEM) is applied to simulate electron optics system of multi-beam klystron with PRPM focusing in this paper. The function of importing 3D magnetic fields from MAFIA is added to TAU. Magnetic induction distribution along Z axis at different radial positions is given out and the electron trajectories are analysed. Optimization of the magnetic focusing system can decrease the radial magnetic induction and improve the electron beam quality. Less time will be needed than other codes, TAU become a very useful tool for multi-beam electron gun design.
Boundary Element Method(BEM) is applied to simulate electron optics system of multi-beam klystron with PRPM focusing in this paper. The function of importing 3D magnetic fields from MAFIA is added to TAU. Magnetic induction distribution along Z axis at different radial positions is given out and the electron trajectories are analysed. Optimization of the magnetic focusing system can decrease the radial magnetic induction and improve the electron beam quality. Less time will be needed than other codes, TAU become a very useful tool for multi-beam electron gun design.
2006, 28(10): 1971-1974.
Abstract:
The effects of thickening the cavity wall and constructing a pair of drift tube in a new complex cavity on the operating mode stability for engineering design are analyzed in this article. Some compensating methods for alleviating the effects are discussed, which shows that rationally increasing the radius of the outer cavity in the complex cavity may effectively realize high purity and stability of the operating mode.
The effects of thickening the cavity wall and constructing a pair of drift tube in a new complex cavity on the operating mode stability for engineering design are analyzed in this article. Some compensating methods for alleviating the effects are discussed, which shows that rationally increasing the radius of the outer cavity in the complex cavity may effectively realize high purity and stability of the operating mode.
2006, 28(10): 1975-1978.
Abstract:
According to a set of analytic equations based on adiabatic compression theory and angular momentum conservation, a single-anode Magnetron Injection Gun(MIG) with a nose-shape accessorial focus pole is studied in this paper. The parameters of the single-anode MIG are optimized through computer simulation with an electron trajectory code (EGUN226). The effect of the ratio of transverse velocity and longitudinal velocity on axial velocity spread is analyzed, which shows that a high-quality electron beam with large and low axial velocity spread can be realized for large current application.
According to a set of analytic equations based on adiabatic compression theory and angular momentum conservation, a single-anode Magnetron Injection Gun(MIG) with a nose-shape accessorial focus pole is studied in this paper. The parameters of the single-anode MIG are optimized through computer simulation with an electron trajectory code (EGUN226). The effect of the ratio of transverse velocity and longitudinal velocity on axial velocity spread is analyzed, which shows that a high-quality electron beam with large and low axial velocity spread can be realized for large current application.
2006, 28(10): 1979-1984.
Abstract:
Being a new research area in radar imaging remote sensing, information extraction using Polarimetric Interferometric SAR (Pol-In-SAR) data, which emerged in late 90s, has gained more and more attention and will become trend and hotspot in remote sensing within next several years. In this paper, research works in regard with Pol-In-SAR and their application are presented and analyzed.
Being a new research area in radar imaging remote sensing, information extraction using Polarimetric Interferometric SAR (Pol-In-SAR) data, which emerged in late 90s, has gained more and more attention and will become trend and hotspot in remote sensing within next several years. In this paper, research works in regard with Pol-In-SAR and their application are presented and analyzed.
