2007 Vol. 5, No. 3

Communication and Information Engineering
A New High Rate Differential Space-Time-Frequency Modulation for MIMO-OFDM
Jun Wang, Shou-Yin Liu
2007, 5(3): 193-197.
Abstract:
In this paper, we propose a new differential space-time-frequency (DSTF) modulation for MIMOOFDM system with four transmit-antennas and arbitrary receive-antennas, which can improve the transmission rate since it can adopt high order quadrature amplitude modulation (QAM) modulation. Our proposed DSTF scheme embeds some full diversity full rate (FDFR) quasi-orthogonal space-time codes (QOSTBC) with QAM modulation into the frequency intervals and adopts the differential modulation in both time and frequency domains. The simulation results demonstrate that the proposed DSTF scheme can improve transmission rate greatly. Compared with the conventional differential unitary space-time modulation (DUSTM), it can get better transmission performance in high transmission rate for MIMO-OFDM system.
A Design of WCDMA RF Transceiver with Its Performance Measuring
Jing-Fu Bao, Zhu-Sheng Kang
2007, 5(3): 198-200.
Abstract:
A 2-GHz radio frequency transceiver is presented and implemented for third generation mobile communications using wide-band code division multiple access (WCDMA) scheme. Performance measuring systems are introduced for transmitter channel and receiver sensitivity, respectively. The transceiver achieves maximum output power of 22 dBm, dynamic range of 85 dB, adjacent channel power rejection ratio (ACPR) of ?41dB@5MHz, and receiver sensitivity of ?119.6 dBm for 128-kb/s data at 3.84-Mcps spreading rate. The measured results indicate the conformity to the required commercial 2.0-GHz WCDMA specification and 3GPP requirements.
Switching Equalization Algorithm Based on a New SNR Estimation Method
Qiang Li, Shao-Qian Li
2007, 5(3): 201-205.
Abstract:
It is well-known that turbo equalization with the max-log-map (MLM) rather than the log-map (LM) algorithm is insensitive to signal to noise ratio (SNR) mismatch. As our first contribution, an improved MLM algorithm called scaled max-log-map (SMLM) algorithm is presented. Simulation results show that the SMLM scheme can dramatically outperform the MLM without sacrificing the robustness against SNR mismatch. Unfortunately, its performance is still inferior to that of the LM algorithm with exact SNR knowledge over the class of high-loss channels. As our second contribution, a switching turbo equalization scheme, which switches between the SMLM and LM schemes, is proposed to practically close the performance gap. It is based on a novel way to estimate the SNR from the reliability values of the extrinsic information of the SMLM algorithm.
Computer and Information Technology
A Trusted Smart Phone and Its Applications in Electronic Payment
Chang-Ying Zhou, Chun-Ru Zhang
2007, 5(3): 206-211.
Abstract:
With the growing intelligence and popularity of mobile phones, and the trend of cellular network's convergence to IP based network, more and more mobile applications emerge on the market. For mission critical applications, like the electronic payment which will be discussed in this paper, the lack of trust in the underlying mobile infrastructure and secure interface to legacy systems (for this case, the banking systems) poses obstacles to their widespread presence in mobile services. Recently, the exposure of hacking of iPhone and other smart phones further emphasizes the criticality of establishing a trust platform for mobile applications. This paper analyzes the building blocks of the trusted smart phone, and proposes a framework to provide a trusted platform for mobile electronic payment. Such a proposed system may allow direct interface to the banking systems due to the banking industry recognized strong security, and hence, may enable its widespread use.
A New DAO Pattern with Dynamic Extensibility
Cheng Fang, Ping Zeng
2007, 5(3): 212-214.
Abstract:
Currently existing data access object (DAO) patterns have several limitations. First, the interface of the patterns and business objects is tightly-coupled, which affects seriously the dynamic extensibility of software systems. Second, the patterns have duplicated implementation codes, which add to difficulties of system maintenance. To solve these problems, a new DAO pattern with stronger independency and dynamic extensibility is proposed in this paper. An example is given to illustrate the using process of the new DAO pattern. The greatest advantages of the new DAO pattern are as follows. If any business object is needed to add to the system, we do not have to modify any codes of the class DAO Factory. All we need to do is to modify the mapping file. Furthermore, because we have only one DAO implementation class to accomplish all the data access to business objects, if some SQL statements are needed to be modified, all we need to do is to modify the DAO implementation class but not need to modify any business objects.
Research and Design of Network Management Construction Based on Mobile AGENT
Yuan-Hui Yu
2007, 5(3): 215-217.
Abstract:
The technical characters of mobile agent (MA) originated in the distributional artificial intelligence domain is introduced. A network management construction based on agent (NMCA) is then proposed. The NMCA structure features are elaborated in detail. A prototype design of NMCA is given by using the jKQML programming. The establishment of NMCA platform will be helpful to reduce the correspondence load of network management and improves the efficiency and the expansion ability of network management systems.
Electronic Materials and Devices
Techniques and Apparatus for Measuring Rotational Core Losses of Soft Magnetic Materials
Jin-Jiang Zhong, You-Guang Guo, Jian-Guo Zhu, Hai-Yan Lu, Jian-Xun Jin
2007, 5(3): 218-225.
Abstract:
In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years.
Out-of-Plane Magnetic Anisotropy and Microwave Permeability of Magnetoelastic FeCoSiB Amorphous Thin Films
Fu-Qiang Xiao, Man-Gui Han, Hai-Peng Lu, Li Zhang, En Li, Long-Jiang Deng
2007, 5(3): 226-229.
Abstract:
The amorphous magnetoelastic Fe66Co17Si1B6 thin films have been deposited by dc magnetron sputtering. A lot of nano-trenches have been observed on the film surfaces by AFM. The permeability of amorphous Fe66Co17Si1B6 thin films was measured within the frequency range of 0.6GHz-10.2 GHz. The ferromagnetic resonance frequency was found to be 1.2 GHz. MFM shows that the domain of thin film is a maze-type pattern, which indicates that an out-of-plane magnetic anisotropy exists. The out-of-plane anisotropy is believed due to the stress-induced magnetic anisotropy. It can be inferred that the internal stress is tensile stress and normal to the film plane.
Circuits, Systems, and Signal Processing
A 400 MHz Low Noise Amplifier at Cryogenic Temperature for Superconductor Filter System
Guo-Bin Wang, Xiao-Ping Zhang, Bi-Song Cao
2007, 5(3): 230-233.
Abstract:
A cryogenic low noise amplifier (LNA) using Agilent high electron mobility transistor (HEMT) for 380 MHz to 480 MHz is designed and fabricated, and the excellent cryogenic performance in superconducting receiver front-end for communication system is achieved. A special input impedance matching topology is implemented to provide low noise figure (NF) and good input matching in this cryogenic LNA design. The measurement results show that the NF is within 0.25 dB from the minimum NF of a single transistor, the power gain is above 20 dB, the flatness is within 1 dB, and the maximum input return loss is lower than ?20 dB in bandwidth.
Optimum Design for a Low Noise Amplifier in S-Band
Xin-Yan Gao, Wen-Kai Xie, Liang Tang
2007, 5(3): 234-237.
Abstract:
An optimum design of a low noise amplifier (LNA) in S-band working at 2-4 GHz is described. Choosing FHC40LG high electronic mobility transistor (HEMT), the noise figure of the designed amplifier simulated by Microwave Office is no more than 1.5 dB, meanwhile the gain is no less than 20 dB in the given bandwidth. The simulated results agree with the performance of the transistor itself well in consideration of its own minimum noise figure (0.3 dB) and associated gain (15.5 dB). Simultaneously, the stability factor of the designed amplifier is no less than 1 in the given bandwidth.
Global Exponential Stability of Almost Periodic Solution of Cellular Neural Networks with Time-Varying Delays
Jing Liu, Pei-Yong Zhu
2007, 5(3): 238-242.
Abstract:
In this paper, global exponential stability of almost periodic solution of cellular neural networks with time-varing delays (CNNVDs) is considered. By using the methods of the topological degree theory and generalized Halanay inequality, a few new applicable criteria are established for the existence and global exponential stability of almost periodic solution. Some previous results are improved and extended in this letter and one example is given to illustrate the effectiveness of the new r sults.
Radar and Array Processing
Estimation of 2-D Angles of Arrival Based on Joint Diagonalization of Two Spatio-Temporal Correlation Matrices
Tie-Qi Xia, Xue-Gang Wang, Qun Wan, Ling Wang
2007, 5(3): 243-247.
Abstract:
In this paper, we propose a two-dimensional (2-D) angles of arrival (AOAs) estimation method based on a joint diagonalization of two spatio-temporal (ST) correlation matrices. The mathematical manipulations proposed in this paper take the structure of the array that enable estimating 2-D AOAs simultaneously without 2-D searching or pairing. The performance comparison shows that the proposed method is better than ST-DOA matrix method.
A New Calibration Method for Microphone Array with Gain, Phase, and Position Errors
Hua Xiao, Huai-Zong Shao, Qi-Cong Peng
2007, 5(3): 248-251.
Abstract:
Microphone array can be used in sound source localization and separation. But gain, phase, and position errors can seriously influence the performance of localization algorithms such as multiple signal classification (MUSIC) algorithm. In this paper, a new calibration method for microphone array with gain, phase, and position errors is proposed. Unlike traditional calibration methods for antenna array, the proposed method can be used in the broadband and near-field signal model such as microphone array with arbitrary sensor geometries in one plane. Computer simulations are presented and simulation results show the new method having good performance.
Fast SAR Imaging Algorithm for FLGPR
Yong Fan, Zheng-Ou Zhou, Jia-Li Xu, Jin-Shan Lin
2007, 5(3): 252-254.
Abstract:
A fast SAR imaging algorithm for near-field subsurface forward-looking ground penetrating radar (FLGPR) is presented. By using nonstationary convolution filter, the refocused image spectrum can be reconstructed directly from the backscattered signal spectrum of target area. The experimental results show the proposed method can fast achieve image refocusing. Also it has higher computational efficiency than the phase-shift migration approach and the delay-and-sum (DAS) approach.
Analysis of Resolution of Bistatic SAR
Tian-Ge Shao, Jian-Guo Wang
2007, 5(3): 255-259.
Abstract:
In this paper, the spatial resolutions at different directions of bistatic synthetic aperture radar (BiSAR) have been derived from the ambiguity function. Compared with monostatic signal to noise ratio, BiSAR's resolutions of a fixed point target are varying with slow time since BiSAR system is space-variant. Constraints for the assumption of space-invariant bistatic topology are proposed in the paper. Moreover, under the assumption of invariance, the change of resolutions at different point in the image scene is taken into account, and we have specified two key parameters that affect resolutions directly and analyzed the way how they influence on the resolutions.
Image Processing
A Fingerprint Minutiae Matching Method Based on Line Segment Vector
Jian-Wei Zhong, Mei Xie
2007, 5(3): 260-263.
Abstract:
Minutiae-based fingerprint matching is the most commonly used in an automatic fingerprint identification system. In this paper, we propose a minutia matching method based on line segment vector. This method uses all the detected minutiae (the ridge ending and the ridge bifurcation) in a fingerprint image to create a set of new vectors (line segment vector). Using these vectors, we can determine a truer reference point more efficiently. In addition, this new minutiae vector can also increase the accuracy of the minutiae matching. By experiment on the public domain collections of fingerprint images fvc2004 DB3 set A and DB4 set A, the result shows that our algorithm can obtain an improved verification performance.
Measuring Fingerprint Image Quality Using the Fourier Spectrum
Qing-Rong Li, Mei Xie
2007, 5(3): 264-267.
Abstract:
The fingerprint image quality has a significant effect on the performance of automatic fingerprint identification system. A method for measure of fingerprint image quality based on Fourier spectrum is proposed. First the band frequency which corresponds to the global average period of ridge is searched. Then the quality score of the fingerprint image is computed by measuring relative magnitude of the band frequency components. The method is verified to have good performance by experiments.
Bioelectronics and Biomedicine
Electric Potential in a Dielectric Sphere Head Produced by a Time-Harmonic Equivalent Current Dipole
Xiao-Yong Duan, Shi-Zheng Peng, Long-Wu Li, Xiao-Chun Liu, Rong Xin
2007, 5(3): 268-271.
Abstract:
A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric medium and dielectric sphere on the electroquasistatic condition are presented. The potential in a 3-layer inhomogeneous spherical head is computed by using this model. The influences on potential produced by time-harmonic character and permittivity are discussed. The results show that potentials in dielectric sphere are affected by frequency and permittivity.
Detrended Fluctuation Analysis of the Human EEG during Listening to Emotional Music
Ting-Ting Gao, Dan Wu, Ying-Ling Huang, De-Zhong Yao
2007, 5(3): 272-277.
Abstract:
A nonlinear method named detrended fluctuation analysis (DFA) was utilized to investigate the scaling behavior of the human electroencephalogram (EEG) in three emotional music conditions (fear, happiness, sadness) and a rest condition (eyes-closed). The results showed that the EEG exhibited scaling behavior in two regions with two scaling exponents 1 and 2 which represented the complexity of higher and lower frequency activity besides band respectively. As the emotional intensity decreased the value of 1 increased and the value of 2 decreased. The change of 1 was weakly correlated with the approach-withdrawal model of emotion and both of fear and sad music made certain differences compared with the eyes-closed rest condition. The study shows that music is a powerful elicitor of emotion and that using nonlinear method can potentially contribute to the investigation of emotion.
Industrial Electronics and Engineering
Total Sensitivity Index Calculation of Tool Requirement Model via Error Propagation Equation
Cun Yue, Li-Mei Xu
2007, 5(3): 278-282.
Abstract:
A new and convenient method is presented to calculate the total sensitivity indices defined by variance-based sensitivity analysis. By decomposing the output variance using error propagation equations, this method can transform the double-loop sampling procedure into single-loop one and obviously reduce the computation cost of analysis. In contrast with Sobol's and Fourier amplitude sensitivity test (FAST) method, which is limited in non-correlated variables, the new approach is suitable for correlated input variables. An application in semiconductor assembling and test manufacturing (ATM) factory indicates that this approach has a good performance in additive model and simple non-additive model.
Comparison of Three SVPWM Strategies
Wei-Feng Zhang, Yue-Hui Yu
2007, 5(3): 283-287.
Abstract:
Three space vector pulse width modulation (SVPWM) schemes, called 7-segment space vector modulation (SVM), 5-segment SVM and 3-segment SVM are studied in this paper. The basic principle of SVPWM is presented. The switching sequence of different scheme is described. The modulation signals, DC bus voltage utilization, and output line voltage harmonic of these schemes are analyzed by the MATLAB software with different modulation index M and frequency modulation index N. The simulation results are analyzed and show that discontinuous modulating functions lead a reduction of switching actions. The DC bus voltage utilization of three schemes is almost the same. For all three SVM, the frequency modulation index N will affect the harmonic characteristic, and the modulation index M will affect DC bus voltage utilization and the harmonic content. The experiment is implemented by the DSP of TMS320F2812. The results validate three algorithms and the simulation.