Table of Content

20 April 2013 Volume 40 Issue 2

  

Original Articles

Rank-1 constraint for camera calibration based on spheres

JIA Jing;WU Chengke

J4. 2013, 40(2):  1-4+42.  doi:10.3969/j.issn.1001-2400.2013.02.001

Abstract ( 1044 )   PDF (1267KB) ( 974 )   Save

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With the rank-1 constraint, a method for camera intrinsic parameters calculation based on spheres is proposed. The geometric interpretation of the rank-1 constraint is explored from the relation of the image of the absolute conic and the sphere image. Three algebraic equations are derived from the rank-1 constraint. The relation of the sphere images and the camera intrinsic parameters is clearly interpreted in vision geometry. Finally, a nonlinear optimized method is used with the three constraint equations for improving the accuracy. Experimental results show that our method is robust. Compared with the traditional method, it can improve the accuracy of the results of the intrinsic parameters.

Delay bound analysis and splitting strategies of concurrent transmission in heterogeneous networks

MA Xiao;SEHGN Min;ZHANG Yan

J4. 2013, 40(2):  5-12.  doi:10.3969/j.issn.1001-2400.2013.02.002

Abstract ( 2694 )   PDF (799KB) ( 866 )   Save

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We focus our attention on how to get optimal performance of concurrent transmission in heterogeneous networks. An equivalent queuing model is used to analyze the end-to-end delay performance of perfect splitting strategy with the theoretical delay bound found. Furthermore, two splitting algorithms, Minimum Queuing Delay based splitting strategy (MQD) and Unified Queuing Management Based Splitting Strategy (UQM), are presented based on the joint resources scheduled in different RATs (Radio Access Technology). In the two-RAT scenario, the two-dimensional discrete-state continuous-time Markov process is used to analyze our schemes with close-formed solutions found. Simulation results demonstrate that our proposed flow splitting strategies utilize the system resources efficiently and outperform current strategies, getting close to the theoretical delay bound especially in the heavy load region.

Rate-compatible network LDPC codes

WANG Jingyi;LI Ying;SUN Yue

J4. 2013, 40(2):  13-17+47.  doi:10.3969/j.issn.1001-2400.2013.02.003

Abstract ( 965 )   PDF (557KB) ( 768 )   Save

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A rate-compatible puncturing algorithm for network LDPC codes is proposed to achieve the minimum error probability, and decoding error probability is derived. The algorithm for finding variable nodes to be deleted based on the tanner graph of network LDPC codes is proposed, which is aimed at minimizing the decoding error probability and optimizing the puncturing pattern. Simulation results illustrate that, at BER=10^-4, the proposed rate-compatible network LDPC codes have a coding gain of about 0.4dB compared with the codes obtained via the existing punctured methods.

Wavelet hierarchical model for aurora images classification

YANG Xi;LI Jie;HAN Bing;GAO Xinbo

J4. 2013, 40(2):  18-24.  doi:10.3969/j.issn.1001-2400.2013.02.004

Abstract ( 1266 )   PDF (2350KB) ( 967 )   Save

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In order to improve the accuracy of aurora images classification, an algorithm based on the wavelet hierarchical model is proposed. In the proposed algorithm, the global and local wavelet features are extracted hierarchically first, then reduced in dimensions through the principal component analysis and used to classify the arc and three corona aurora images by the use of the support vector machine. By comparing the classification accuracy and time consumption, the optimal parameters in the wavelet hierarchical model are experimentally obtained and the validity of principal component analysis in feature optimization is verified. Experimental results show that the proposed algorithm improves the classification accuracy to a great degree with an acceptable time consumption compared with classical algorithms. Classification results between each two types of aurora images also provide some potential ways to improve the accuracy.

Frequency domain iterative block DFE for SC-FDMA uplink system

WANG Qiucai;YUAN Chaowei;ZHANG Jinbo;LI Yingxue

J4. 2013, 40(2):  25-30.  doi:10.3969/j.issn.1001-2400.2013.02.005

Abstract ( 1226 )   PDF (588KB) ( 840 )   Save

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Focusing on intersymbol interference(ISI) and multiuser interference(MUI) existing in single-carrier frequency-division multiple access(SC-FDMA) in multipath fading channels, a new multiuser receiver based on diversity combining is designed, and a novel frequency domain iterative block decision feedback equalization(DFE) approach for multiuser SC-FDMA is proposed. By exploiting the input-decision correlation, it optimizes the tap coefficients of the feedforward and feedback filters, in such a way that the maximized signal-to-interference-plus-noise ratio(SINR) is achieved for each iterative process, thus removing residual interference, and gradually improving the reliability of the detected data. Simulation results show that the proposed approach effectively reduces the bit error rate(BER) and provides significant robustness against multipath fading.

Normal-distribution-test algorithm for range spread target detection

WEN Xiang;LIU Hongwei

J4. 2013, 40(2):  31-35+53.  doi:10.3969/j.issn.1001-2400.2013.02.006

Abstract ( 1021 )   PDF (503KB) ( 848 )   Save

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A range spread target detection algorithm based on the normal distribution test is proposed. Based on the fact that the range spread target signal generally does not follow normal distribution, the range spread target detection problem is equivalent to the normal distribution test problem. Analysis show that the normal distribution test detector has the characteristic of constant false alarm rate. The performance of the proposed detector is analyzed. Numerical experimental results based on simulation and measured high range resolution profile data show that the proposed detector outperform the energy integration detector.

Electrothermal characteristics of second breakdown in diodes under the EMP stress

REN Xingrong;CHAI Changchun;MA Zhenyang;YANG Yintang

J4. 2013, 40(2):  36-42.  doi:10.3969/j.issn.1001-2400.2013.02.007

Abstract ( 2170 )   PDF (666KB) ( 829 )   Save

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2D transient electrothermal simulations are carried out of the second breakdown in a diode with a p-n-n⁺ structure under the EMP stress. The paper begins with a study of the variations of the electric field and the current density distribution in a diode as well as the terminal voltage and the terminal current with the time duration of the EMP stress, followed by a research on the variations of the trigger temperature, trigger current and trigger energy with the delay time of the second breakdown. The research results show that the second breakdown in diodes is caused by the thermal effect, and that the current concentration is not its necessary condition. In addition, the triggering temperature and triggering current increase with a decrease in the delay time, while the triggering energy decreases with a decrease in the delay time. Computational permanent damage threshold energies of the diode are in good agreement with experimental data.

Integrated design method considering closed-loop stability for the slider-crank mechanism

LI Sulan

J4. 2013, 40(2):  43-47.  doi:10.3969/j.issn.1001-2400.2013.02.008

Abstract ( 1042 )   PDF (481KB) ( 839 )   Save

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The slider-crank mechanism is a transmission mechanism extensively used in engineering practice. It is necessary to use the control system for getting a satisfactory trajectory. So the mechanism design is composed of two parts, structural design and control design. These two parts impact each other and are tightly coupled, and the separate design can not obtain the best performance. Hence integrated design is imperative. By making use of the Lyapunov function, an integrated design considering stability is proposed in this paper, seeing that stability is the most basic requirements of a closed-loop system. Simulation results show that this method can effectively carry out the mechanism design, reduce the body weight, optimize mechanism performance and save the design cost simultaneously.

Practical electromagnetism-like mechanism algorithm

JIANG Jianguo;WANG Shuangji;LIU Yongqing;SHANG Haibao;ZHU Yineng

J4. 2013, 40(2):  48-53.  doi:10.3969/j.issn.1001-2400.2013.02.009

Abstract ( 1003 )   PDF (487KB) ( 799 )   Save

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The function optimization principle of the original Electromagnetism-like mechanism (EM) algorithm and some problems of it are analyzed, such as large computation, low convergence rate, and pathological feature in the total force formula. A new pratical EM algorithm is proposed according to the problems above. The power formula is simplified by adopting the method for normalizing the objective function value. The correction factor is introduced into the total force formula, so that the pathological feature in the total force formula is eliminated, the impact of the distance factor on the force between population particles weakened, and the convergence rate increased. Experiments show that the improved algorithm has a faster convergence speed and higher solution accuracy.

Service-related data sampling methodology

GAI Bingshuai;WANG Jinlin;LIU Xue

J4. 2013, 40(2):  54-59+158.  doi:10.3969/j.issn.1001-2400.2013.02.010

Abstract ( 1051 )   PDF (561KB) ( 807 )   Save

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Based on the analysis of current popular data sampling methods, this paper proposes a service-related data sampling methodology in the field of service data sampling. Firstly, this method puts service data items with the same sampling cycle in a queue, and sorts the queue by a heuristic algorithm. Secondly, this method completes data sampling process for service data items in the queue in order. Simulation results show that this method can complete service data sampling in less than the period required by service analysis, and can reduce the redundant sampling rate by 60%～90％.

STDMA protocol based on fuzzy control and MIMO for ad hoc networks

LI Jiandong;CAI Xuelian;ZHANG Yu;ZHANG Zhen

J4. 2013, 40(2):  60-66+193.  doi:10.3969/j.issn.1001-2400.2013.02.011

Abstract ( 914 )   PDF (1008KB) ( 794 )   Save

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In the traditional Space Time Division Multiple Access (STDMA) protocol, the time slot is not allocated dynamically and the idle slots potentially exist. To address the issue, based on fuzzy logic control and Multiple Input Multiple Output (MIMO) technology, a novel STDMA protocol (MIMO-STDMA) is proposed. In MIMO-STDMA, the number of slots and the frame length allocated to a mobile node are determined dynamically through the judgment and calculation based on regulation of the fuzzy controller. Utilizing the reservation and stream control gain of MIMO, in the allocated slots, a node employs full antennas to transmit data. On the contrary, in the unallocated slots the node reserves the transmission by 4-way handshaking with the carrier sense. Finally, simulations are conducted to evaluate the performance of the proposed protocol. The results show that the MIMO-STDMA outperforms the STDMA in terms of throughput and slot utilization.

Image decomposition using the non-convex functional

BAI Jian;FENG Xiangchu

J4. 2013, 40(2):  67-71+137.  doi:10.3969/j.issn.1001-2400.2013.02.012

Abstract ( 1366 )   PDF (5197KB) ( 869 )   Save

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This paper proposes a new model for image decomposition by non-convex functional minimization. Instead of using the Banach norm as the fidelity term, we use the integral of the square of residual component divided by its gradient as the fidelity term. This non-convex fidelity term has a very low value for the texture image and a high value for the geometric image, so it is appropriate for image decomposition. The gradient descent procedure is used to solve the proposed minimization problem, which leads to evolving a new nonlinear second-order partial differential equation(PDE) to a steady state. Compared with the total variation minimization(TV) model and the fourth-order PDE(OSV) model, the proposed nonlinear second-order PDE maintains many more sharp edges, so the texture part has less cartoon information. Experimental results also demonstrate that our model performs better than the standard TV and OSV models in image decomposition.

Cross-layer optimization and design based on QoS guarantees in the relay system

TANG Lun;ZHANG Rongrong;CHEN Qianbin

J4. 2013, 40(2):  72-81.  doi:10.3969/j.issn.1001-2400.2013.02.013

Abstract ( 1040 )   PDF (761KB) ( 731 )   Save

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In order to improve the throughput and guarantee the quality-of-service (QoS) for a relay system, a cross-layer design scheme which combines adaptive modulation and coding (AMC) at the physical layer with cooperative hybrid automatic repeat request (CHARQ) at the link layer is proposed over the Nakagami-m fading channel. Firstly, the system packet loss rate (PLR) is described and analyzed through the state transition diagram. Then, the queuing delay is derived using the queuing theory. Moreover, a cross-layer model for maximizing system throughput is presented under the constraints of PLR, queuing delay and transmission delay. Numerical results show that the cross-layer design scheme combining CHARQ with AMC can achieve the optimal throughput, the smallest PLR and the shortest queuing delay and transmission delay.

Novel detection and parameters estimation of a high-speed multi-target

ZHENG Jibin;FU Weibo;SU Tao;ZHU Wentao

J4. 2013, 40(2):  82-88.  doi:10.3969/j.issn.1001-2400.2013.02.014

Abstract ( 1233 )   PDF (1281KB) ( 849 )   Save

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A novel algorithm for high-speed multi-target detection and parameters estimation with narrowband radar is proposed. Firstly, velocity and acceleration are roughly estimated with the combination of compensating range migration in the frequency domain and fractional Fourier transform. And then, based on the coarse estimation, keystone transform and fractional Fourier transform are employed to estimate the fold factor and acceleration accurately. In the case of multi-target, range migration, Doppler spread and velocity ambiguity, this algorithm is suitable, and the performance of the targets detection and parameters estimation is improved owing to the utilization of the coherent integration in a low signal-to-noise ratio. The computational load is greatly reduced by combination of coarse and accurate estimation. The validity of the proposed algorithm is demonstrated by computer simulation.

Chinese text semantic representation for text classification

SONG Shengli;WANG Shaolong;CHEN Ping

J4. 2013, 40(2):  89-97+129.  doi:10.3969/j.issn.1001-2400.2013.02.015

Abstract ( 1341 )   PDF (633KB) ( 903 )   Save

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Text representation based on word frequency statistics is often unsatisfactory because it ignores the semantic relationships between words, and considers them as independent features. In this paper, a new Chinese text semantic representation model is proposed by considering contextual semantic and background information on the words in the text. The method captures the semantic relationships between words using Wikipedia as a knowledge base. Words with strong semantic relationships are combined into a word-package as indicated by a graph node, which is weighted with the sum of the number and frequency of the words it contains. The contextual relationship between words in different word-packages is stated by a directed edge, which is weighted with the maximum weight of its adjacent nodes. The model retains the contextual information on each word with a large extent. Meanwhile, the semantic meaning between words is strengthened. Experimental results of Chinese text classification show that the proposed model can express the content of a text accurately and improve the performance of text classification. Compared to Support Vector Machines, Text Semantic Graph-based Classification can improve the efficiency by 7.8％, reduce the error rate by 1/3, and show more stability.

Generalized Keystone transform algorithm for dim moving target detection

ZHAO Yongbo;ZHOU Xiaopei;WANG Juan

J4. 2013, 40(2):  98-102+122.  doi:10.3969/j.issn.1001-2400.2013.02.016

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Aimed at the problem that the accumulation result varies with the choice of the benchmark pulse used in the Keystone transform to correct range migration, a generalized Keystone transform algorithm is proposed for detecting the dim moving target via long-term coherent integration. The algorithm first searches for the minimum error of discrete time sampling and the corresponding pulse from digital pulse compression. Afterwards, this pulse echo is used as the benchmark in the Keystone transform, by which all the pulse echoes are corrected into the same range resolution cell. Accordingly, the maximum output after accumulation is obtained. Computer simulation and real data processing results are given to verify the effectiveness of the proposed method.

Pre-processing method for multi-dimension parameters estimation for the multi-target in the MIMO radar

QIN Guodong;LI Peng;CHEN Baixiao

J4. 2013, 40(2):  103-109+206.  doi:10.3969/j.issn.1001-2400.2013.02.017

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In Multiple-Input Multiple-Output (MIMO) radar, the separated echoes of a target with a high speed are located in neither the same range bin nor the same Doppler bin. As a result, the parameters (including range, azimuth and elevation) of the target can't be estimated using the traditional supper-resolution algorithms. In this paper, velocity estimation is used to form compensation expression, which pre-processes the echoes. And the range and Doppler migration are corrected. Then the spatial spectrum estimation algorithm is applied to the corrected echoes to obtain the range, azimuth and elevation of targets. Simulation results indicate that the feasibility and validity of the methods presented are better than those of MUSIC.

Detection and parameter estimation of sawtooth linear frequency modulated continuous wave signal

ZHU Wentao;ZHENG Jibin;SU Tao;ZHU Kairan

J4. 2013, 40(2):  110-116.  doi:10.3969/j.issn.1001-2400.2013.02.018

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Aiming at application of long time accumulation for the detection and parameter estimation of linear frequency modulated continuous wave (LFMCW), a novel method based on the joint zero frequency searching method and quasi-MTD method is proposed to detect the sawtooth LFMCW (SLFMCW) signal and estimate its parameters. Firstly, detection of the SLFMCW signal and estimation of its period are realized by use of the zero frequency searching method. And then, the quasi-MTD method based on cyclocorrelation is utilized to finish the estimation of phase parameters and initial time-offset. The estimation of the period, chirp-rate, initial frequency and initial time-offset can be effectively realized by the method, which has low computational complexity and can provide good estimation performance in a low signal-to-noise ratio (SNR) owing to long time accumulation. Computer simulations verify the effectiveness of the algorithm.

Simple single-antenna amplify-and-forward relaying scheme for orthogonal space-time block codes

LI Chuan;LIU Wei

J4. 2013, 40(2):  117-122.  doi:10.3969/j.issn.1001-2400.2013.02.019

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A simple amplify-and-forward (AF) relaying scheme based on Orthogonal Space-Time-Codes (OSTBC) is proposed, which applies to the scenario where only one single antenna at the relay and an arbitrary number of antennas at the destination. Also, the analytical performance of the proposed scheme is investigated in the context of Rayleigh fading channels. Specifically, the probability density function (pdf) of the received SNR is characterized and the symbol error rate (SER) of different modulation schemes is derived. Simulation confirms the validity of analytic results.

Micro-Doppler parameter estimation from a fraction of the period data with the MMSE criterion

ZUO Lei;LI Ming;ZHANG Xiaowei

J4. 2013, 40(2):  123-129.  doi:10.3969/j.issn.1001-2400.2013.02.020

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The micro-Doppler characteristic of a rotation target can be represented by a sinusoid. Sometimes the integrating time is shorter than the rotation period. In this case, a new method based on the minimal mean-square error(MMSE) for estimating the micro-Doppler parameter from a fraction of the period data is proposed. The error function is constructed between sinusoid and micro-Doppler signal extracted from the time-frequency distribution of the echoes. Solving the error function in the criterion MMSE, we can obtain the rotation micro-Doppler parameters, i.e. rotation rate and rotation radius. We also prove that the discretisation error and Gaussian white noise induced by extracting the micro-Doppler signal have little effect on the accuracy of the estimated parameters. The validity and accuracy of the proposed method are evaluated via both simulation and experimental data.

New method for estimating 2-D DOA in the coherent source environment based on data matrix reconstruction

WANG Ling;LI Guolin;LIU Jianqiang;MAO Weiping

J4. 2013, 40(2):  130-137.  doi:10.3969/j.issn.1001-2400.2013.02.021

Abstract ( 1235 )   PDF (650KB) ( 876 )   Save

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The performance of classical two dimensional (2-D) Direction-Of-Arrival (DOA) estimation algorithms degrade substantially in the presence of coherent environment. A new DOA matrix method——DOA matrix method based on data matrix reconstruction (DMR-DOAM) is proposed for 2-D DOA estimation in the coherent source environment. The proposed algorithm reconstructs two Toeplitz equivalent covariance matrices by using cross-correlation information among receiving data from arrays. Decorrelation and 2-D DOA estimation can be realized via the eigen-decomposition of the new DOA matrix. The algorithm can retain the advantages of the traditional DOA matrix method, such as automatical parameter alignment and no need of 2-D search spectrum peak. The equivalent covariance matrices only use the middle column of classical covariance matrices, so the calculation amount is reduced, and the algorithm can be realized easily. Furthermore, the paper analyzes the estimation performance and influencing factors of the proposed algorithm. Theoretical analyses and simulation results both show that the proposed algorithm is effective.

Optimization design and simulation analysis of earth reconnaissance satellite constellation

WEI Juan;ZHANG Run

J4. 2013, 40(2):  138-141+147.  doi:10.3969/j.issn.1001-2400.2013.02.022

Abstract ( 861 )   PDF (474KB) ( 789 )   Save

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A low orbit constellation is designed based on the revisiting cycle in order to realize the intermittent reconnaissance to the global region. Firstly, a constellation design model is built based on the orbit height and inclination of the nearly circular recursive orbit. The single orbit plane and triple orbit plane parameters,which satisfy earth reconnaissance mission, are determined. Then the complex shape optimization method is selected to optimize the two kinds of constellation. Considering the cover performance as the objective function, the orbit inclination, longitude of the ascending node, and inter-satellite phase are selected as optimization variables. Finally, constellation performance is evaluated using the coverage gap number, coverage percentage and average response time. It is shown that the constellation performance of the triple orbit plane is superior to that of single orbit plane, and can fulfill the earth reconnaissance objective.

Priority semi-persisting scheduling scheme for voice over LTE service

LU Meilian;ZHANG Kai

J4. 2013, 40(2):  142-147.  doi:10.3969/j.issn.1001-2400.2013.02.023

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This paper proposes a new scheduling algorithm for allocating the LTE radio resource, Priority Semi-Persisting Scheduling(PrSPS). PrSPS calculates the priority of the user equipment using the user grade, PRBs needed, average channel quality and average transmission rate. Adopting this priority method in semi-persisting scheduling mechanism can avoid the competition between resource scheduling signalling and voice date, improve the radio resource utilization and scheduling efficiency, increase the user capacity of VoLTE and improve satisfaction of VoLTE users. Using the NS-3 simulation platform, the paper evaluates the performance of PrSPS.

New type bandgap reference for UHF RFID tag

DU Yongqian;ZHUANG Yiqi;LI Xiaoming;JING Xin;DAI Li

J4. 2013, 40(2):  148-152+200.  doi:10.3969/j.issn.1001-2400.2013.02.024

Abstract ( 1081 )   PDF (1991KB) ( 862 )   Save

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A novel low-voltage, low-power current mode bandgap reference circuit for the passive UHF RFID tag is presented. The I_CTAT current is generated by V_BE of the BJT transistor. The I_CTAT current is generated by the MOSFET biased in the sub-threshold region, based on the theory that the I-V curve of the sub-threshold MOSFET shows an exponential relationship. The circuit is designed and implemented by TSMC 0.18μm CMOS technology. The biggest variation of V_ref of the reference is smaller than 1.75％. Test results show that the power of the circuit is 0.65μW, and that the minimum operating voltage is 0.829V. The active area of the circuit is about 0.04mm². As a result, the read sensitivity of the tag with the proposed bandgap reference circuit is -16dBm.

Method for predicting the operating range of multispectral thermal imaging systems

LIU Xin;ZHANG Jianqi;WANG Xiaorui;LIU Dongdong;ZHANG Fudi

J4. 2013, 40(2):  153-158.  doi:10.3969/j.issn.1001-2400.2013.02.025

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A method for predicting the operating range of multispectral thermal imaging systems with a distributed fusion architecture is proposed by utilizing the Triangle Orientation Discrimination (TOD) performance model. Specifically, by considering the facts that the apparent target/background differential temperatures in different wavebands are inconsistent because of the effect of atmospheric attenuation on the radiation of a target and that a fusion rule has an impact on the performance of the system, the calculation process of atmospheric transmittance and the concrete fusion rule are introduced into the TOD performance model of the system. And the direct comparison between the inherent target/background differential temperature and a TOD threshold is made. According to the TOD criteria for different discrimination levels, the relations of the reciprocal angular subtense of a triangle pattern and the range of the system to a triangle pattern are achieved when these two values are equal and the target acquisition ranges are obtained by solving these equations. The validation by the experimental results and simulation images suggests that this approach can predict the operating range of multispectral thermal imaging systems efficiently.

Design of a miniature broadband internal antenna for PD detection in GIS

GUO Hongfu;XU Caixiang;TANG Jinfeng;FU Mi;BAI Li'na

J4. 2013, 40(2):  159-163+171.  doi:10.3969/j.issn.1001-2400.2013.02.026

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According to the analysis of the relationship between the impedance and bandwidth of the dipole antenna, a novel elliptical plane internal antenna feeding by a coaxial line is presented. It consists of an elliptical monopole and a rectangular grounding piece and has the virtues of broad band, high gain and small size. The antenna can be used for ultrahigh frequency (UHF) partial discharge (PD) detection in the gas-insulated switchgear (GIS). The size is achieved by using the simulation software Ansoft HFSS and the optimum size of total antenna is 90mm×45mm. A prototype is constructed and studied, and then measured. The antenna covers a large band from 781MHz to 2.00GHz, with the VSWR less than 2.5 and a max gain of 3.55dB. Simulated and tested results are in good agreement and the radiation pattern and gain characteristics are given.

Specific radar emitter identification using multiset canonical correlation analysis

WANG Lei;SHI Ya;JI Hongbing

J4. 2013, 40(2):  164-171.  doi:10.3969/j.issn.1001-2400.2013.02.027

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In order to improve the performance of a specific radar emitter recognition system, a novel framework based on Multiset Canonical Correlation Analysis (MCCA) is proposed. It extracts the Doppler cuts of the ambiguity function (AF) of each radar signal as the initial feature set and employs MCCA to perform feature fusion and redundancy reduction in such a set. By using label information, the further developed Multiset Discriminant Canonical Correlation Analysis (MDCCA) achieves competitive performance while retaining the low order of canonical vectors. Thanks to the direct fusion strategy, the proposed scheme not only avoids the uncertainty in determining the optimal cut of AF in previous methods, but also extends the conventional CCA, which can only deal with two sets of feature vectors, to the multiset version. Experiments on real radar emitter data demonstrate the effectiveness of the proposed methods.

Data synchronization algorithm controlled by the intelligent terminal

LI Liya;HU Xiaohong;XIN Zhenguo

J4. 2013, 40(2):  172-180+212.  doi:10.3969/j.issn.1001-2400.2013.02.028

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To integrate different vendors' cloud storage services, we put forward a data synchronization algorithm based on HASH fingerprint information, which combines strictly consistent data synchronization and weak consistent data synchronization. Intelligent terminal controled data synchronization calculation maps HASH fingerprint information into HASH fingerprint information file which is independent of the needed synchronous data. The algorithm is used to calculate the hash code for filename and file content. First we match the filename's hash code and then the file content, which strategy can reduce the requirement for the hash algorithm. The simulation experiment uses the improved BKDR hash algorithm, the results achieve 20000 order-of-magnitude file repeatability test and verify that the data synchronization algorithm can be implemented independently by the intelligent terminal, instead of relying on the server, and can integrate different vendors' cloud storage services.

Channel reservation MAC protocol with adaptive power control mechanism carrier sensing

YUAN Yunjie;LI Bo;YAN Zhongjiang

J4. 2013, 40(2):  181-186.  doi:10.3969/j.issn.1001-2400.2013.02.029

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A channel reservation MAC protocol with the adjustable transmission power and carrier sensing threshold, called PC-CRM, is proposed. PC-CRM solves the problems of poor transmission quality, low network capacity and high energy consumption, which are caused by the distributed contention based channel access scheme in Ad Hoc networks. By employing power control into the channel reservation schemes, PC-CRM adjusts the transmission power and carrier sensing threshold to the optimum values, such that the channel is multiplexed in space. Additionally, PC-CRM is also capable of stabilizing the channel reservation, improving the network capacity, and reducing the energy cost. Simulation results show that, compared with IEEE 802.11DCF and the basic channel reservation scheme, PC-CRM performs better in terms of the throughput, energy efficiency and delay jitter.

New high performance non-data-aided frequency estimation and implementation of QPSK

ZHANG Yi;OUYANG Zhixin;DENG Yunkai;WANG Yu

J4. 2013, 40(2):  187-193.  doi:10.3969/j.issn.1001-2400.2013.02.030

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A new scheme for modulation removal for Non-Data-Aided (NDA) QPSK signals is proposed. The algorithm based on this new scheme can make a large range of frequency estimation cooperated with the DFT coarse frequency estimation method. Compared with the estimation algorithm using DFT and interpolation, the new scheme can endure more frequency fluctuation and estimate accurately the frequency offset when the effset varies slowly. Simulations and FPGA implementation prove the new scheme's good performance that it closes to CRB even at a low SNR.

Signal reconstruction algorithm based on the probabilistic structured sparse model

HE Yibao;BI Duyan

J4. 2013, 40(2):  194-200.  doi:10.3969/j.issn.1001-2400.2013.02.031

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In order to describe structured sparsity of the signal accurately, a probabilistic structured sparse model is constructed for signal reconstruction in compressive sensing(CS). Based on the structured sparse model, Boltzmann distribution is introduced to describe structured sparsity of the signal support rather than to describe the signal directly. Based on Bayesian CS, the maximum a posterior estimate of signal support is computed with the prior distribution and the Gaussian likelihood model of measurement, and then the signal is reconstructed using signal support. Experimental results show that, for the signal with the support known, the proposed algorithm is obviously superior to BP and OMP and that for the signal with the support unknown, its performance outperforms that of BP and OMP in the condition of a high measurement noise level and low reconstruction error tolerance.

Fast blind equalization algorithm based on PSP

ZHAO Liang;WANG Chunmei;SUN Hongbo

J4. 2013, 40(2):  201-206.  doi:10.3969/j.issn.1001-2400.2013.02.032

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The usage of conventional blind equalization algorithm is limited in the application of burst signal communication due to its dissatisfaction of fast equalization. Per-survivor processing (PSP) exhibits good performance of channel-tracking and solves the problem of decision delay, but it increases the computational complexity. In this paper, PSP is applied to realize the fast tracking of the channel parameter and the coefficients of the linear equalizer are obtained by combining the inverse non-minimum phase with FIR approximation methods. Then this algorithm may be switched over to DD-LMS to achieve fast blind equalization. Simulation results indicate that the algorithm is valid for the application of blind equalization in burst signal communication.

Block diagonalized MMSE GMD vector precoding

GENG Xuan;SUN Zuolei;LIU Feng;MA Yinghong

J4. 2013, 40(2):  207-212.  doi:10.3969/j.issn.1001-2400.2013.02.033

Abstract ( 1204 )   PDF (558KB) ( 897 )   Save

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Based on the block diagonalization (BD) for the multiuser Multiple-input Multiple-output (MIMO) downlink channel, a vector precoding (VP) combined with geometric mean decomposition (GMD) based on the minimum mean square error (MMSE) criterion is proposed. The multiuser multi-antennas channel is decomposed into parallel effective sub-channels, and then the mean square error (MSE) of the transceiver signal is obtained based on the effective sub-channel. The VP combined with GMD is derived based on the MMSE criterion, and the perturbation vector contains the perturbation vector expanding constellation and residual interference vector. The MSE expression is then achieved based on the derivation results, and the realization block diagram is concluded finally. Simulation results show that the proposed algorithm outperforms the conventional BD method and its expanded method in bit error rate (BER).