Table of Content

26 September 2010, Volume 28 Issue 5

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Communication Engineering

Weight Distributions of Linear Codes from Perfect Nonlinear Functions of Dembowski-Ostrom Type

LI Ping1, LI Chao1;2, ZHOU Yue1

2010, 28(5):  441-446.  doi:10.3969/j.issn.0255-8297.2010.05.001

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Abstract: Perfect nonlinear functions of Dembowski-Ostrom type is the main type of perfect nonlinear functions. Only one class of perfect nonlinear functions does not belong to the Dembowski-Ostrom type. We first give the definition of the perfect nonlinear functions of Dembowski-Ostrom type, and generalize the construction
of two linear codes to this type. We then show connection between this type of functions and the nondegenerate quadratic forms over finite fields. We also summarize properties of the preimage distributions of the quadratic forms. Based on the theory of quadratic forms and exponential sums, we determine the weight distributions of two classes of linear codes from all perfect nonlinear functions of the Dembowski-Ostrom type using a unified approach.

A Location-Based Trust Routing for MANET

WANG Kun1, WU Meng2, LU Wei-feng3

2010, 28(5):  447-456.  doi:10.3969/j.issn.0255-8297.2010.05.002

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 To deal with the safety weakness in resisting active attacks from malicious nodes, trust metric is introduced to combat the attacks by loading a trust model on the proposed distance-based location-aided routing (DBLAR). The improved routing algorithm ST-LAR uses direct trust and recommendation trust to prevent malicious nodes with low trust value from joining the forwarding. Simulation results show that STLAR
can effectively resist attacks from malicious nodes. Its performance is also better than DBLAR in terms of average end-to-end delay, packet successful delivery ratio and throughput.

Coordinated Multi-cell Multi-mode Transmission Scheme with Limited Feedback  

SUN Dong, QIU Ling

2010, 28(5):  457-462.  doi:10.3969/j.issn.0255-8297.2010.05.003

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Coordinated multi-cell multi-antenna transmission can effectively mitigate inter-cell interference in cellular MIMO systems, thus improving cell edge throughput. However, the performance heavily depends on the channel state information and cooperation among multiple base stations. In this paper, we investigate
the impact of limited feedback on the multi-cell local joint precoding based on 2-cell cooperative transmission. According to the location of cell edge users, we propose a multi-mode transmission method. Simulation results show that it can significantly enhance cell edge throughput.

Timing Offset in OFDM Systems Based on Conjugate-Symmetric Preamble

2010, 28(5):  463-469.  doi:10.3969/j.issn.0255-8297.2010.05.004

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This paper studies symbol synchronization methods based on the conjugate-symmetric preamble for OFDM systems in multipath fading channels. We analyze statistic properties of timing metric based on conjugate-symmetric correlation, and show that the compound-conjugate-symmetric structure is formed when two paths are separated by an even number of samples. The timing metric corresponding to the compoundconjugate- symmetric structure may be large under some conditions. We analyze the timing offset when the peak value of timing metric is used to detect the desired timing position, and show that the compound-conjugatesymmetric structure and the first path with small gain may result in backward shift in timing position. A large backward shift can cause inter-symbol and inter-channel interferences, seriously degrading the OFDM system performance. Simulation results confirm the analysis.

Effects of AM-AM Conversion on DOA Estimation in Tracking and Data Relay Satellite System

TAN Xiao-heng, HU Yang, LIU Yu

2010, 28(5):  470-475.  doi:10.3969/j.issn.0255-8297.2010.05.005

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In the reverse link of tracking and data relay satellite system (TDRSS), AM-AM conversion in the high-power amplifier for frequency-division multiplexing (FDM) signals causes severe inter-modulation interference to the signals in different channels. The interference results in distortion of the channel signals. The present work uses power series to analyze the influence of AM-AM conversion on the amplifier’s magnitude consistency among the channels, and establish a mathematical model of the influence of magnitude inconsistency on DOA estimation. Theoretical analysis and simulation results show that AM-AM conversion in high-power amplifier does not affect the offset of the estimated angle, but reduces the spectral peak within the spatial angle and increases the 3 dB bandwidth. AM-AM conversion also deteriorates the DOA estimation performance.

Signal and Information Processing

Registration of Out-of-Focus and Blurred Images Based on Orthogonal Moment Combined Invariant

DAI Xiu-bin, ZHANG Hui, SHU Hua-zhong, LUO Li-min

2010, 28(5):  476-484.  doi:10.3969/j.issn.0255-8297.2010.05.006

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Abstract: We propose a new Legendre moment invariant based method to deal with registration of images which are simultaneously degraded by out-of-focus blurring and geometric deformation. We use the Harris corner detector to extract feature points, and construct a new set of combined blur and geometric invariantsof Legendre moment as a measure to establish correspondence between feature points of the images to be registered. This correspondence is then used to estimate the transformation parameters to realize image registration. Experimental results show that the proposed method can effectively register degraded images with better performance compared to some other methods.

A New Adaptive Steganography Using Wet Paper Code

XI Ling, PING Xi-jian, ZHANG Tao

2010, 28(5):  485-492.  doi:10.3969/j.issn.0255-8297.2010.05.007

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Abstract: We present a new scheme termed wet paper code adaptive steganography(WPCAS). Using the wet paper code, the receiver can recover the secrete message correctly without knowing the elements used to carry secrete bits. This gives the sender complete freedom to choose the collection of elements as message carrier.
With this advantage, the new scheme builds a proper adaptive rule (AR) which can automatically adjust its parameters to make the collection of message carrying elements better match the noise-like region of bit-plane so that visual imperceptibility is enhanced. The fact that the AR is unknown to anyone except the sender
prevents analyzers from launching AR-based attacks, making the new scheme more security. Comparison between the WPCAS scheme and the adaptive BPCS steganography show that the proposed WPCAS is better in terms of visual imperceptibility and resistance against steganalysis based on statistics of complexity.

Lattice Boltzmann Method for Vector Image Denoising

WANG Zhi-qiang1;2, YAN Zhuang-zhi1, ZHANG Rui1, QIAN Yue-hong3

2010, 28(5):  493-500.  doi:10.3969/j.issn.0255-8297.2010.05.008

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 We present a new lattice Boltzmann method for vector image nonlinear diffusion by embedding vector image’s edge feature into the relaxation parameter of the Lattice Boltzmann equation and designing high efficient equilibrium distributions. This overcomes the problems of poor efficiency and the difficulty in parallelization of the traditional numerical methods using nonlinear diffusion model for vector image denoising. To keep the algorithm stable, the method can iterate with large step to improve computation efficiency. Influence of equilibrium distribution on computation accuracy and efficiency is evaluated in the numerical simulation of second dimensional diffusion problem. To illustrate effectiveness of the method, color images contaminated by Gaussian noise and impulsive noise are tested. Experimental results and the analysis show that computation accuracy and efficiency of the proposed method are better than that of the traditional numerical method such as additive operator splitting (AOS) algorithm

Cluster Analysis for Selection of Time Series Interferometric SAR Imagery

PAN Bin, SHU Ning

2010, 28(5):  501-506.  doi:10.3969/j.issn.0255-8297.2010.05.009

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Abstract: We propose a method to select interferometric SAR pairs for time series differential SAR Interferometry (D-InSAR) by using cluster analysis. In this approach, proper decorrelation factors are selected to construct a feature space, and decorrelation factors of all possible SAR interferometric pairs are mapped to the space. Thus, interferometric pair selection is converted to a problem of feature space clustering. A cluster algorithm is developed based on the principle of interferometric pair selection. This way, selected interferometric images corresponding to the clustering result are obtained. Experimental results show that the proposed approach is simple and effective.

A New QRS Detector Based on Empirical Mode Decomposition

ZHU Wei-fang,\quad ZHAO He-ming,\quad CHEN Xiao-ping

2010, 28(5):  507-512. 

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According to the characteristics of energy distribution of electrocardiogram (ECG) signals, a novel QRS complex detection scheme based on empirical mode decomposition (EMD) is proposed in the paper. The EMD method decomposes the ECG signal into a set of oscillatory components called intrinsic mode functions (IMFs).
Energy contained in each IMF is then calculated and normalized. According to the energy distribution, interference caused by baseline bias, baseline wander and high T wave is detected and restrained. A simple adaptive threshold is chosen to detect the QRS complex. Several measures for avoiding false positive and false
negative detections are taken. Performance of the method was tested using all 48 records from the MIT-BIH Arrhythmia Database. An average detection rate of 99.91\% was achieved, showing good reliability of the proposed detector.

Modeling and Simulation of Space-Time Array GPS IF Signal

ZHU Shan-hu, LI Rong-bing, LIU Jian-ye, WEN Li

2010, 28(5):  513-518.  doi:10.3969/j.issn.0255-8297.2010.05.011

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In this paper, we establish a model of single antenna GPS intermediate frequency signal by analyzing the characteristics of GPS signal. The array-antenna space-time intermediate frequency(IF) signal is modeled based on the single antenna model. To ensure accuracy of the model, satellite clock error, atmospheric error, receiver clock error and noise are considered in the analysis. We also design a space-time GPS data simulator,
which is flexible, scalable and easy to use. The signal model is validated with spectral analysis and its accuracy verified by space-time adaptive processing.

Electronic Engineering

Design of Network-on-Chip Groupware Based on Hamming Code and Built-in Self-Test

OUYANG Yi-ming, NI Jin-zhao, LIANG Hua-guo

2010, 28(5):  519-526.  doi:10.3969/j.issn.0255-8297.2010.05.012

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Abstract: This paper presents a structure of resource-network interface and router which can handle both soft errors and hardware fault of the router. We add a code circuit to generate parity bit, and a decoding circuit to correct one bit of software error in the resource network interface circuit. We also set a built-in self-test
(BIST) circuit in the standard router and add some flag registers in a RC module which can decide whether the adjacent router is broken-down or not. If the next hop router is fault-free for the transferred data, the data will be forwarded by the original port. Otherwise, the data will be forwarded by another port. The proposed method can avoid the router hardware fault. Experiments show that, compared to other NoC groupware, the proposed structure has higher reliability and lower overhead for the resource-network interface. In addition, part of the standard modules can be reused. Functional simulations show that a smaller hardware overhead can be achieved.

Biorthorgonal Multiresolution Time-Domain Method and Application to Electromagnetic Scattering

GAO Qiang-ye1;2, ZHOU Jian-jiang1, CAO Qun-sheng1

2010, 28(5):  527-532.  doi:10.3969/j.issn.0255-8297.2010.05.013

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 We study a biorthogonal multiresolution time-domain (bi-MRTD) method and use it to analyze electromagnetic scattering properties and compute radar cross sections (RCS) of three-dimensional objects. Compactly supported biorthogonal Cohen-Daubechies-Feauveau(CDF) wavelets with rigorous interpolation property are employed as spatial basis functions to expand the field components. A rigorous three-dimensional calculation formula is derived by applying the wavelet-Galerkin sampling method. Dispersion properties of the bi-MRTD methods are studied. Anisotropic perfectly-matched layer (APML) is chosen to truncate the computational space. The incident wave is introduced by using the total-field/scattered-field (TF/SF) technique. Theoretical analyses and experimental results show that the bi-MRTD method can save considerable computational resources without loss of accuracy in comparison with FDTD and the MRTD method based on non-compactly supported Battle-Lemarie (B-L) wavelets.

Application of Improved Adaptive Domain Decomposition FDTD in Waveguide Analysis

MENG Ling-qin1;2, LI Peng1;2

2010, 28(5):  533-539.  doi:10.3969/j.issn.0255-8297.2010.05.014

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This article presents improved adaptive domain decomposition finite difference time domain(IADDFDTD).We apply adaptive boundary test to the voltage on the boundary. The new algorithm avoids computational error caused by instability of electric field intensity on test boundaries, and can get more sub-domains
than the original ADD-FDTD and enhance computation speed. Analysis on applications of waveguide discontinuities indicates correctness and effectiveness.

Computer Science and Applications

Hybrid Memory Scheme for Genetic Algorithm in Dynamic Environments

CHEN Hao1, LI Ming2, CHEN Xi2

2010, 28(5):  540-545.  doi:10.3969/j.issn.0255-8297.2010.05.015

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In order to effectively solve dynamic optimization problems, a new hybrid memory scheme that consists of short-term memory and long-term memory is proposed. Information to be memorized includes the best individual and the probability vector of current population. Information of short-term memory is extracted to build the next population in each generation. Long-term memory is assigned for the short-term memory when a environmental change is detected. A new genetic algorithm is thus constructed based on the hybrid memory. Performance of the algorithm is verified in different environments including non-cyclic, cyclic, and cyclic with noise. Computation results indicate that this algorithm is superior to similar algorithms in dealing with dynamic optimization problems.

Control and System

A Novel Parallel Manipulator of 2T2R and Positional Analysis

JI Ye1, LIU Hong-zhao1, FAN Cai-xia1;2, QIAO Zhan-hong1

2010, 28(5):  546-550.  doi:10.3969/j.issn.0255-8297.2010.05.016

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Abstract: Based on five degree-of-freedom (5-DOF) of parallel manipulator of 4-UPU, a novel spatial parallel manipulator of 4-UPU/PPS is deduced. From the theory of screw, we show that this manipulator possess 2T2R (two-translational and two-rotational) DOFs, and establish an equation of position. Since forward positional
analysis of parallel manipulator is difficult, based on the constrained length of limps, we build an unconstrained nonlinear optimization fitness function of this manipulator. The problem of forward positional analysis is thus converted to a multi-objective optimization problem that can be solved with the dynamic variable-weighting
multi-objective particle swarm optimization (PSO) algorithm which seeks the global minimum of the nonlinear optimization function. The result of 20 groups of random forward positional analysis is consistent with the actual position and orientation. Therefore the problem of forward positional analysis is solved using the
proposed parallel manipulator.