Journal of Xidian University 2014 Vol.41
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Performance analysis of the polarization-space-time adaptive processing
DU Wentao;LIAO Guisheng;YANG Zhiwei
J4    2014, 41 (1): 1-5.   DOI: 10.3969/j.issn.1001-2400.2014.01.001
Abstract902)      PDF(pc) (613KB)(906)       Save

By the utilization of the additional polarized information, the minimum detectable velocity could be improved for space time adaptive processing under the polarimetric radar system. In this paper, the performance of polarization space time adaptive processing is analyzed and compared with the traditional space-time adaptive processing based on the output signal to clutter plus noise ratio, and the primary affecting factors of three dimensional processing are indicated. A preliminary result against an airborne simulation data verifies the conclusion.

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Cited: Baidu(3)
Monte Carlo mobile node localization for NLOS environment
KUO Yonghong;ZHOU Wenwen;CHEN Jian
J4    2014, 41 (1): 6-12.   DOI: 10.3969/j.issn.1001-2400.2014.01.002
Abstract1026)      PDF(pc) (767KB)(701)       Save

Enhanced Monte Carlo Boxed (EMCB), based on the broadcasting messages of one-hop neighbor nodes, is proposed  in a mobile wireless sensor network for NLOS environment. The utilization efficiency of nodes is improved in the way of message flooding. The located nodes are used as the virtual anchor nodes in order to improve the location precision in the network with few anchors, optimizing the sample boxes of the neighbor nodes. Besides, both the theoretical limit of connectivity and the previous location information are used to enhance the filtering performance. Taking advantage of the one-hop messages, all the nodes are located layer-by-layer. Finally, the results of simulation show that the location precision is improved compared with the traditional algorithms in any situation. Especially, a good performance is achieved with fewer anchor nodes.

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Cited: Baidu(2)
Temporal profile algorithm based on comparison filtering for detection of the infrared dim small target
DONG Weike;ZHANG Jianqi;SHAO Xiaopeng;LIU Delian
J4    2014, 41 (1): 13-17.   DOI: 10.3969/j.issn.1001-2400.2014.01.003
Abstract1042)      PDF(pc) (1935KB)(677)       Save

The detection performance of the traditional temporal profile algorithm deteriolates when the dim small target has a velocity correspmding to equivalent that of cloud edge clutters. This paper proposes a temporal profile algorithm based on comparison filtering as a responding method to the fake-alarm occurrence existing in the traditional detection algorithm. Based on the analysis of the time domain characteristics of the dim small target, cloud edge clutters as well as the stationary background, the characteristic of the temporal profile is adopted to restrain the stationary background, and then the spatial domain comparison filter is structured based on the fact that the pixels of the cloud edge clutters are continuous in spatial domain while the pixels of the dim small target are discrete, and the images after removal of the static background are filtered by the comparison filter; lastly, the connecting line of the stagnation points (CLSP) based filtering is used to realize the detection of the dim small target. Simulation data show that this algorithm can significantly eliminate the fake-alarm caused by the cloud edge clutters with an equivalent velocity of the target, thus further improving the detection probability of the dim small target.

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Cited: Baidu(3)
Gaming network selection scheme considering performance-price ratio maximization in heterogeneous wireless networks
SONG Jianfeng;LI Jiandong
J4    2014, 41 (1): 18-22.   DOI: 10.3969/j.issn.1001-2400.2014.01.004
Abstract901)      PDF(pc) (562KB)(709)       Save

A heterogeneous network selection scheme based on game theory is proposed. A non-cooperation game model is formed which is aimed to maximize the overall profits of heterogeneous networks according to the integrated quality of service and the pricing scheme of each network. The network selection scheme is proposed to maximize the result of the quality of service versus price by means of Nash Equilibrium of the game. Analysis and simulation results validate the advantage of the scheme.

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Joint pilot and iterative decoding carrier synchronization for the short burst transmission system
SUN Jinhua;WANG Xuemei;WU Xiaojun
J4    2014, 41 (1): 23-28+63.   DOI: 10.3969/j.issn.1001-2400.2014.01.005
Abstract941)      PDF(pc) (700KB)(733)       Save

Considering the low estimation accuracy and small synchronization range of carrier synchronization algorithms in low signal to noise ratio (SNR) for short burst communication systems, a joint pilot and iterative decoding soft-output carrier synchronization algorithm is proposed. Firstly, the received pilot sequence is extracted and modulation is removed, with the modulation-removed signals made cross-correlated. Then the summation of all the correlation values is used to perform initial carrier parameters estimation. Secondly, the pilot sequence is reused with the soft-output information based on the extended Turbo decoder to obtain fine frequency and phase estimation values. Theoretical analysis and simulation results show that the coarse estimation algorithm can satisfy the requirements of the frequency estimation range and estimation accuracy, and preamble-middle pilot placement is optimal for a certain length of the data frame; The turbo decoder can obtain more reliable soft-output information with small residual frequency offset after initial coarse synchronization when the normalized frequency offset is less than 1.5×10-3, with the joint pilot and soft-output of the decoder used to estimate fine carrier parameters, which can make the turbo code achieve optimal BER performance.

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Cited: Baidu(2)
Application of the invasive weed optimization algorithm to the pattern synthesis of array antennas
LIU Yan;JIAO Yongchang;ZHANG Yaming;WANG Xinkuan
J4    2014, 41 (1): 29-33+86.   DOI: 10.3969/j.issn.1001-2400.2014.01.006
Abstract1048)      PDF(pc) (751KB)(798)       Save

For overcoming the problem of slow convergence speed and local optimum by using the existing intelligent optimization algorithms in the pattern synthesis of antenna arrays with nulls, notches and sidelobe reduction, a novel invasive weed optimization(IWO) algorithm is presented, and an adaptive IWO is designed to improve the convergence speed and make a balance between the global and local searching ability. Simulation results show that, compared with other existing algorithms, the proposed algorithm performs better, with higher convergence speed and better computation accuracy.

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Cited: Baidu(4)
Effective capacity analysis of MIMO beamforming
GUO Xiaobo;MO Daihui;WANG Lifeng;YI Kechu
J4    2014, 41 (1): 34-37.   DOI: 10.3969/j.issn.1001-2400.2014.01.007
Abstract772)      PDF(pc) (438KB)(711)       Save

Effective capacity describes the rate upper bound of the communication system under the quality of service(QoS) limitation. While the foregoing performance analysis focuses mainly on the single input single output and multiple input single output systems, this paper considers the effective capacity of the multiple input multiple output(MIMO) beamforming scheme. Given that the modulation(M-QAM or M-PSK) is restricted, we investigate the representative transmission scheme of MIMO beamforming: maximal ratio combining transmission, for which the closed-form formula of effective capacity is derived. Simulation results not only demonstrate the effectiveness of our performance analysis, but also show the relationship between effective capacity and average signal-to-noise ratio as well as the relationship between effective capacity and QoS parameter for various antenna configurations.

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Cited: Baidu(1)
Analysis of the characteristics of squint circular scanning SAR and its imaging method
LIAO Yi;YANG Zemin;XING Mengdao;BAO Zheng;BAO Min
J4    2014, 41 (1): 38-44+74.   DOI: 10.3969/j.issn.1001-2400.2014.01.008
Abstract1138)      PDF(pc) (1399KB)(660)       Save

Circular scanning SAR(CSSAR) is a new mode for fast large area SAR imaging by increasing the azimuth scanning speed. The squint CSSAR possesses the advantages that the side-looking CSSAR does not have due to its unique observing direction. However, the available signal characteristic analysis and imaging method for side-looking CSSAR become questionable when applied to the squint CSSAR. This paper establishes the echo range model and analyzes several parameters such as azimuth scanning speed, Doppler characteristics and azimuth resolution according to the moving feature of squint CSSAR. Furthermore, the internal relationship between the squint CSSAR and the classical stripmap mode is revealed. The range approximation model as well as the corresponding imaging method is analyzed. Computer simulation results validate the conclusions and the imaging method.

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Cited: Baidu(3)
Method for sparse component analysis in the shearlet domain
JI Jian;LI Xiao
J4    2014, 41 (1): 45-52+146.   DOI: 10.3969/j.issn.1001-2400.2014.01.009
Abstract913)      PDF(pc) (10518KB)(709)       Save

In applications of the image blind source separation, the traditional method of Independent Component Analysis(ICA) computes the mixed matrix by using source image directly, without using the prior knowledge that images can be represented sparsely in the transform domain, and it can not lead to a better effect. Based on the capacity of image sparse representation by shearlet, a method of sparse component analysis in the shearlet domain is presented. The image mixed source is first transformed to the shearlet domain and obtains a shearlet coefficient, then the sparsest coefficient is selected by computing kurtosis, and finally the sparse coefficient is used as the input of the ICA method to realize image separation. The complexity of the solving procedure represents a significant decrease since it chooses a less sparse coefficient. Experimental results show that, compared with the traditional ICA method, the method in this paper leads to a better separation effect and shortens the operation time of the algorithm.

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Cited: Baidu(1)
Novel dual-mode square loop microstrip bandpass filter
SUN Shoujia;WU Bian;LIANG Changhong
J4    2014, 41 (1): 53-56.   DOI: 10.3969/j.issn.1001-2400.2014.01.010
Abstract1039)      PDF(pc) (1079KB)(739)       Save

This paper presents a novel dual-mode square loop resonator with a compact size. Firstly, the odd-even-mode method is utilized to analyze the resonant property of the proposed resonator since its structure is symmetrical, and the passband center frequency can be easily tuned by changing the lengths of a pair of loaded open-ended stubs. Secondly, source-load coupling is introduced to produce a new transmission zero and improve the passband selectivity. Finally, a microstrip dual-mode bandpass filter (BPF) centering at 1.95GHz with a 3dB fractional bandwidth (FBW) of 37.7% is designed and fabricated. The measured and simulated results in good agreement are presented.

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Cited: Baidu(3)
Adaptive waveform selection approach for target tracking
JIN Biao;JIU Bo;LIU Hongwei;SU Tao
J4    2014, 41 (1): 57-63.   DOI: 10.3969/j.issn.1001-2400.2014.01.011
Abstract1165)      PDF(pc) (704KB)(706)       Save

Within an adaptive interacting multiple model (IMM) framework, an approach to selecting the transmitted waveform of radar is proposed. The adaptive IMM algorithm is attained when the constant-velocity (CV) model and the current statistical model are applied to the IMM filter. Firstly, the error ellipse orthogonal method is derived from information theory, and an equivalent form is given in terms of control theory. According to the equivalent form, the range and velocity tracking error can not be adjusted effectively using the error ellipse orthogonal method. To solve this problem, an adaptive transmitted waveform selection approach is proposed based on the minimum mean-squared error, combining with the adaptive IMM algorithm. Simulations show that the proposed algorithm is feasible and effective.

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Cited: Baidu(2)
Feature quantitative model and performance analysis of infrared imaging under strong radiation source disturbance
GUO Bingtao;WANG Xiaorui;JIN Weiguo;WANG Xiaobing;HUANG Xiaomin
J4    2014, 41 (1): 64-68.   DOI: 10.3969/j.issn.1001-2400.2014.01.012
Abstract1052)      PDF(pc) (559KB)(705)       Save

The strong radiation source(such as battlefield fire) has become an important factor affecting the infrared imaging quality. First, a feature quantitative model of infrared imaging under strong radiation source disturbance is built based on the imaging signal conversion mechanism and by simultaneously considering the signal response characteristic,dynamic range, automatic gain characteristic(AGC) and gray level quantization and display. Then, a simulation of the output image of the infrared imaging system is performed on the basis of the model mentioned above and the simulation platform developed in our laboratory. Finally, a quantitative analysis of the relationship between the energy of the strong radiation source and the brightness(contrast) of the system's output image is made. The results will be used for providing a theoretical basis and technical support for the research on the infrared imaging system anti-interference ability protection in the battled environment.

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Cited: Baidu(1)
Autofocusing the synthetic aperture radar imagery by the fast back-projection algorithm
ZHANG Lei;LI Haolin;XING Mengdao;BAO Zheng
J4    2014, 41 (1): 69-74.   DOI: 10.3969/j.issn.1001-2400.2014.01.013
Abstract1051)      PDF(pc) (3171KB)(732)       Save

Time-domain Fast Back-Projection (FBP) is an accurate and efficient solver to generate high-resolution Synthetic Aperture Radar(SAR) images. However, motion errors seriously degrade the performance of the FBP image when the accuracy of the position system does not reach the wavelength level. In this paper, we propose a novel multi-aperture map drift (MAMD) algorithm, which is implemented within the FBP iterations. The autofocus processing is realized by estimating the shift of sub-aperture images and it keeps the high accuracy of the FBP algorithm. Experiments by using real airborne SAR data validate the effectiveness of the proposed algorithm.

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Cited: Baidu(7)
Method for transforming cyclic circuits into acyclic equivalents
DI Zhixiong;SHI Jiangyi;MA Peijun;ZHANG Yi;YUAN Li;HAO Yue;XU Zhao
J4    2014, 41 (1): 75-80.   DOI: 10.3969/j.issn.1001-2400.2014.01.014
Abstract1276)      PDF(pc) (557KB)(711)       Save

The cyclic circuit is capable of reducing the area and power consumption, but it is difficult for tools such as static timing analyzers to analyze and compute. Furthermore, the simulation and DFT for the cyclic circuit are more expensive and complicated. Thus, a method for transforming cyclic circuits into acyclic equivalents based on the SAT(Boolean Satisfiability) is presented in this paper in order to remove the unwanted cycles in the high-level synthesis process. Different from the available researches, the SAT and static logic implication are introduced in this paper. Meanwhile, by analyzing the structure and mechanism of the cyclic circuits, some novel rules are presented to obtain the acyclic equivalents more precisely and effectively. Experiments are performed in our scientific research projects and the IPs which come from Opencore. And the transforming time and the area are decreased by 28% and 16%.

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Differential co-localization method using the X-ray pulsar
FENG Dajun;XU Luping;SONG Shibin;TIAN Xi
J4    2014, 41 (1): 81-86.   DOI: 10.3969/j.issn.1001-2400.2014.01.015
Abstract1455)      PDF(pc) (700KB)(644)       Save

Relative navigation traditionally using inter-satellite links demands higher inter-satellite time synchronization, and has no ability of absolute positioning and timing. In this paper, we propose a relative navigation model of X-ray pulsar-based co-localization. The main satellite receives the radiation pulse signal from X-ray pulsars, and sends the arrival time and individual pulse's feature to adjacent satellites through inter-satellite links. Then by detecting the inter-satellite time difference of X-ray pulsar signals we can establish the location equation to find the inter-satellite relative position. We deduce the error correction equation of the pulse TOA prediction model and analyze the identifiability of individual pulses of the pulsar. The method proposed in this paper is less influenced by the TOA prediction model, ephemeris error, etc. It is helpful for achieving on-line self-adaption correction of the TOA prediction model and combined orbit determination of satellite constellation.

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Cited: Baidu(1)
Fast frequency sweep analysis for antennas mounted on platforms using the wire-surface model
Lü Zhengliang;GONG Shuxi;ZHANG Pengfei;ZHAO Bo;WANG Fuwei
J4    2014, 41 (1): 87-91.   DOI: 10.3969/j.issn.1001-2400.2014.01.016
Abstract1176)      PDF(pc) (1414KB)(646)       Save

The best uniform rational approximation in conjugation with the method of moments (MoM) is applied to analyze the wide-band electromagnetic characteristic of the wire-surface objects. For the analysis of wire-surface objects, all the wire-surface models are substituted by surface-surface models, and then the radiation problem can be solved more efficiently by the Chebyshev approximation for the surface current combined with discrete wavelet transform (DWT). This technique offers a considerable computational saving in terms of memory. To improve the accuracy, the polynomial series is replaced by the Maehly series and the best uniform rational approximation is obtained. Numerical examples are performed to demonstrate the validity.

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Cited: Baidu(4)
Mechanism analysis and physical process of bipolar junction transistor failure due to HPM injection from the base
FAN Juping;YOU Hailong;JIA Xinzhang
J4    2014, 41 (1): 92-97.   DOI: 10.3969/j.issn.1001-2400.2014.01.017
Abstract887)      PDF(pc) (1719KB)(658)       Save

In order to determine the influence of HPM on BJT, the physical process and model are proposed based on the experimental phenomena of BJT injecting HPM from the base. Simulation results by using the model and process proposed in the paper show that the main mechanism of failure and degradation of BJT caused by HPM is that the induced voltage pulse generated by HPM leads to the burn-up and the formation of the fuse element and defect in the base. The burnt area and the number of defects which vary with the power and time of HPM on the devices cause the device failure and the change of DC characteristics.The simulation result is in good agreement with the phenomena of the BJT HPM effect experiment, which indicates that the analysis in this paper is correct.

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Cited: Baidu(2)
Multi-objective evolutionary algorithm based on preference for constrained optimization problems
DONG Ning;WANG Yuping
J4    2014, 41 (1): 98-104+188.   DOI: 10.3969/j.issn.1001-2400.2014.01.018
Abstract1117)      PDF(pc) (528KB)(812)       Save

Constrained optimization problems (COPs) are converted into the bi-objective optimization problem and solved with a new preference based multi-objective evolutionary algorithm. A new hybrid crossover operator is proposed to improve the search ability in the evolutionary process, and also a novel fitness function with preference based on the achievement scalarizing function (ASF) which is used in the method of weighted metrics in multi-objective optimization is presented. The new fitness measures the merits of individuals by the weighting distance from individuals to the reference point, where the reference point and the weighting vector afford the preference for selection. In different evolutionary stages, the reference point and weighting vector are chosen adaptively according to the individuals in population to make a tradeoff between the preferences to the two objectives. Numerical experiments for several standard test functions with different characteristics illustrate that the new proposed algorithm is effective and efficient.

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Cited: Baidu(5)
New image enhancement algorithm based on the SLIP model
ZHANG Guangyan;WANG Junping;WANG Song;CAO Honghua;XU Dan;LI Jin;LI Changjiang
J4    2014, 41 (1): 105-109+169.   DOI: 10.3969/j.issn.1001-2400.2014.01.019
Abstract1693)      PDF(pc) (1958KB)(767)       Save

Image enhancement technology plays an important role in human life, social production, etc. This paper presents a new algorithm for image enhancement based on the SLIP (Symmetric Logarithmic Image Processing) model. Firstly, we get the SLIP image enhancement algorithm about image gray values based on the analysis of the existing logarithmic image enhancement algorithm. Then the SLIP image enhancement algorithm is simplified to the simple mathematical operation using the vector operation of the SLIP model. The proposed algorithm can enhance the image not only with the mode of the transmitted light image but also with the mode of the reflected light image. By means of subjective evaluation and EMEE objective evaluation, experimental results show that the proposed algorithm can enhance the image detail and improve the overall image contrast. Meanwhile, the algorithm overcomes the disadvantage that LIP image enhancement algorithm cannot enhance the images with the mode of the reflected light image.

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Cited: Baidu(3)
Sensing insider threat based on access vectors
ZHANG Hongbin;PEI Qingqi;WANG Chao;WANG Meihua
J4    2014, 41 (1): 110-115.   DOI: 10.3969/j.issn.1001-2400.2014.01.020
Abstract939)      PDF(pc) (580KB)(634)       Save

The hierarchy-based access control model and access vectors are defined by using the access control relationship. A method is developed for quantizing the insider threat on resources and actions in the information system. Then a full real time assessment is obtained by using access vectors. Compared with other models, this model improves the precision and objectivity of the quantization without a prior knowledge of the system. Experimental results show that the access vector based on the hand hierarchy-based access control model can effectively assess the insider threat in real-time and can be used to build the insider threat sense system.

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Cited: Baidu(5)
Cross layer reputation mechanism based secure routing protocol for WMNs
LIN Hui;MA Jianfeng
J4    2014, 41 (1): 116-123.   DOI: 10.3969/j.issn.1001-2400.2014.01.021
Abstract1006)      PDF(pc) (632KB)(674)       Save

Wireless mesh networks are faced with various security threats due to their special infrastructure and communication mode, where the internal attacks aiming at routing security and user privacy security are one of the most challenging issues. In this paper a novel cross layer reputation mechanism is first proposed to identify and isolate the internal malicious nodes. Then, a privacy-aware secure routing protocol CR-HWMP based on the proposed reputation mechanism is proposed. Performance analysis and simulation results show that CR-HWMP can effectively implement the privacy preserving and defend against the internal attacks such as black hole and gray hole, and improve the reliability, robustness and security of the wireless mesh networks efficiently.

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Cited: Baidu(7)
Histogram shifting based adaptive reversible watermarking algorithm with a high capacity
WANG Xiang;LI Ke;FU Kaiyuan;LUO Fan
J4    2014, 41 (1): 124-129.   DOI: 10.3969/j.issn.1001-2400.2014.01.022
Abstract904)      PDF(pc) (553KB)(689)       Save

The traditional histogram shifting based reversible watermarking algorithm can only embed at most 1.0 bit watermark information into one pixel in single-pass embedding. Therefore, we have to use multi-pass embedding to achieve a higher embedding capacity. However, in the second-pass and the subsequent embedding process, the prediction error will be affected by the embedding distortion, which reduces the embedding efficiency. To this end, this paper proposes an improved reversible watermarking algorithm by employing histogram shifting. The algorithm embeds 1.0 bit or more bit watermark in one pixel in terms of the context of image. Experimental results show that the algorithm can effectively improve the embedding capacity while maintaining a high image quality.

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Cited: Baidu(3)
Generation and analysis of the excellent 2n-periodic binary sequences
NIU Zhihua;LI Zheng;LI Zhe;XIN Mingjun
J4    2014, 41 (1): 130-134.   DOI: 10.3969/j.issn.1001-2400.2014.01.023
Abstract828)      PDF(pc) (435KB)(629)       Save

The 2n-periodic binary sequence with high linear complexity and high k-error linear complexity is defined as an excellent sequence. We design a genetic algorithm for generating excellent sequences and studying their features. Choosing the N-periodic binary sequences, where N=8, 16, 32, k=N/4, we search the resulted sequences by the genetic algorithm with various parameters, and compute the linear complexity profiles of results sequences by using the Lauder-Paterson algorithm, to confirm that the obtained sequences are the real excellent sequences. By numerous experiments, we speculate that the k-error linear complexity of the N-periodic binary excellent sequence meets the formula LCk(S)≤N-2k+1, when k=N/4、N/8 (we also do experiments on sequences with periods 64, 128 and 256). By the brute-force method we obtain that the proportion of the excellent sequence in all binary sequences of the same period is 1/4.

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α-generalized resolution principle based on the lattice-valued first-order logic system
XU Weitao;ZHANG Wenqiang;XU Yang;ZHANG Dexian
J4    2014, 41 (1): 135-139.   DOI: 10.3969/j.issn.1001-2400.2014.01.024
Abstract1209)      PDF(pc) (417KB)(668)       Save

In the framework of the lattice-valued logic system based on the lattice implication algebra, the α-resolution principle based on the lattice-valued logic system is extended from generalized clauses set to general generalized clauses set. In this paper, the α-generalized resolution principle is presented in the lattice-valued first-order logic system LF(X). At the same time, the soundness theorem is established in LF(X). By using the lift lemma, the weak completeness theorem is also proved. This work can provide a new automated reasoning technology in order to establish novel generalized resolution methods for lattice-valued logic systems.

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Novel method for analyzing the performance of the 1bit IR-UWB receiver in the presence of timing jitter
ZHANG Chao;YUE Guangrong;YIN Huarui
J4    2014, 41 (1): 140-146.   DOI: 10.3969/j.issn.1001-2400.2014.01.025
Abstract1036)      PDF(pc) (580KB)(665)       Save

A novel method based on the Central Limit Theorem (CLT) is proposed to analyze the performance of the 1bit Impulse-Radio Ultra-WideBand(IR-UWB) receiver in the presence of a timing jitter. First, the sampled signal with timing jitter is expressed as a linear function of the sampled signal without jitter and timing jitter through first-order Taylor series expansion. Then by the CLT, the decision variable of the 1bit receiver is considered as Gaussian distributed and the bit error rate (BER) is derived. After that, an upper bound of the averaged BER is also provided based on the distribution of random timing jitter. The given analytical result is the first analytic expression of the BER performance of the 1bit receiver with timing jitter and can be used for the case where the 1bit receiver has a linear interference. Experimental results show that the proposed upper bound agrees with the actual performance of the 1bit receiver very well and can be used for both Gaussian distributed and uniform distributed timing jitter.

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The 3D transmission scheme in DVB-S2
SHAO Yongqing;ZHANG Baiyu;HUANG Yan
J4    2014, 41 (1): 147-152.   DOI: 10.3969/j.issn.1001-2400.2014.01.026
Abstract832)      PDF(pc) (627KB)(706)       Save

According to the characteristics of DVB-S2 streams and 2D data transmission, three kinds of transmission modes based on the data link layer are provided in the DVB-S2 channel, and the corresponding transmission protocol stacks are also given. According to the regulation of transmission modes, the transmission efficiency is calculated in each case and then a comparison is made. Synthesizing various factors, we conclude that each transmission mode has its own advantages and disadvantages in different applications, and that none of them cannot be completely replaced by others.

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Polarization-dependent mutiband low RCS reflection screen
YAO Xu;CAO Xiangyu;GAO Jun;ZHAO Yi;YANG Huanhuan
J4    2014, 41 (1): 153-157.   DOI: 10.3969/j.issn.1001-2400.2014.01.027
Abstract1062)      PDF(pc) (2592KB)(598)       Save

A novel radar reflection screen composed of the polarization-dependent mutiband artificial magnetic conductor (PDMAMC) and perfect electric conductor cells is proposed. The PDMAMC is realized by etching a complementary split ring resonator (CSRR) on the patch of a conventional artificial magnetic conductor. Around the two/three operational frequencies of the PDMAMC-elements for different electric field polarizations, the reflection of the PDMAMC and perfect electric conductor have opposite phases, so for any normal incident plane wave the reflections cancel out. The basic principle is discussed and a sample is measured. The results show that the proposed method is feasible and effective for polarization-dependent mutiband RCS reduction.

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Improved sparse multipath channel equation method
YANG Yuan;LI Mingyang;WANG Xuhua
J4    2014, 41 (1): 158-163.   DOI: 10.3969/j.issn.1001-2400.2014.01.028
Abstract1042)      PDF(pc) (604KB)(689)       Save

Traditional channel equation methods are based on the multi-path richness hypothesis, which is complicated and inefficient in sparse channels. In this paper, a sparse multi-path channel equation method is proposed. The sparse channel estimation is carried out using a small number of pilot tones based on Compressed Sensing (CS). The equation inverse filter is derived from the channel estimation. The procession of inverse filter solution is modeled as an optimization problem and a greedy algorithm is proposed which can bring about a near optimal solution. The new algorithm requires fewer iterations than linear prediction and gets almost optimal filter parameters when the rank is high enough. The modularized structure of the greedy algorithm is designed which is less complicated and can be easily realized. Simulation shows that the BER performance of the proposed equation method is improved significantly with the increase of SNRs. At 15dB of the SNR it gains 10dB in power efficiency relative to LMS.

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Cited: Baidu(4)
SAARS microstrip antenna design with an asymmetrical structure and a tilted beam
LI Sijia;CAO Xiangyu;GAO Jun;ZHENG Qiurong;YANG Huanhuan
J4    2014, 41 (1): 164-169.   DOI: 10.3969/j.issn.1001-2400.2014.01.029
Abstract1329)      PDF(pc) (2025KB)(728)       Save

A circularly polarized microstrip antenna with the tilted beam of 30° through the asymmetrical structure combing the single-arm archimedean spiral antenna with the helix antenna is constructed in order to make the beam tilted. The bandwidth, tilted beam, and radiation characteristics have been improved through the width optimization and coaxial feed line selection. This antenna can realize the directional radiation of circularly polarized microwaves in a definite frequency band and has a bandwidth of 16.7% (for Voltage Standing Wave Ratio(VSWR)<2, Axis Ratio(AR)<3dB and the tilted beam of 30°) in the condition of the vertical aperture external excitation with a coaxial feed line. Simulated and measured results show that this antenna has a wideband, high gain, and tilted beam with circularly polarized microwaves.

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Cited: Baidu(1)
Actuator placement optimization of optimum vibration control for tensegrity structures
JIANG Jie;LI Tuanjie
J4    2014, 41 (1): 170-175.   DOI: 10.3969/j.issn.1001-2400.2014.01.030
Abstract879)      PDF(pc) (1343KB)(664)       Save

The simulated annealing algorithm is employed to implement the actuators placement optimization for a tensegrity structure, and the effect of actuator positioning on the vibration control of the structure is analyzed. To this end, the ANSYS model of a 4-floor tensegrity structure is built, and the state space control equation of the structure through mode transform and mode truncation is deduced. Based on optimal vibration control for the tensegrity structure, the energy of the system with respect to actuator locations is chosen as the optimal criterion. Simulation results indicate that the optimization method is effective, and that the performance of vibration control of the tensegrity structure is improved dramatically when actuators are placed in the optimal position.

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Cited: Baidu(2)
Approximated expression for the achievable residual intersymbol interference obtained by multimodulus blind equalizers
WANG Cheng;YANG Bin
J4    2014, 41 (1): 176-181.   DOI: 10.3969/j.issn.1001-2400.2014.01.031
Abstract851)      PDF(pc) (663KB)(683)       Save

A closed approximated formed expression for the achievable residual inter-symbol interference(ISI) is proposed for the adaptive equalizers that adopt the multimodulus algorithm. The expression depends on the step-size parameter, equalizer's tap length, input signal statistics, signal noise ratio and channel power. Simulation proves that the expression shows the exact relationship between residual inter-symbol interference and involved parameters. Since the channel power and signal noise ratio of the expression are measurable or can be calculated, this new approximated expression can be a useful tool for choosing the step-size and tap length for designing an equalizer, and for making direct performance comparison between blind equalizers based on distinct algorithms.

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Joint calibration algorithm in the presence of mutual coupling and channel discord via rotational invariance techniques
WANG Ling;LIU Jianqiang;LI Guolin;ZHANG Zhen;YANG Jikun
J4    2014, 41 (1): 182-188.   DOI: 10.3969/j.issn.1001-2400.2014.01.032
Abstract894)      PDF(pc) (604KB)(683)       Save

The performance of subspace estimation algorithms degrades substantially in the presence of mutual coupling and channel discord by the perturbance of the steering matrix. Classical self-calibration algorithms need multidimensional search, optimization and iteration, and large calculation quantity. In order to avoid these shortcomings, a novel joint calibration algorithm using rotational invariance techniques is proposed in this paper. Two sub-arrays' steering matrix can maintain the rotational invariance property in the presence of array errors by switching channels and selecting sub-arrays according to the characteristic of the mutual coupling matrix. So, the estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm is applicable to mutual coupling and channel discord scenarios. The algorithm requires neither searching the spectrum peak nor estimating error parameters, and the calibration of array errors does not need an additional calculation quantity. Simulation results show that the proposed algorithm can restrain mutual coupling and channel discord. The performance of the algorithm is equivalent to the performance of the standard ESPRIT algorithm without errors.

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Cited: Baidu(3)
Traffic allocation algorithm of multi-radio access transmission based on minimizing delay over heterogeneous networks
ZHENG Jie;LI Jiandong;LIU Qin;SHI Hua;YANG Xiaoniu
J4    2014, 41 (2): 1-8.   DOI: 10.3969/j.issn.1001-2400.2014.02.001
Abstract897)      PDF(pc) (1837KB)(872)       Save

To minimize the traffic arrival delay, a joint network selection and traffic allocation algorithm is proposed for parallel multi-radio access transmission. The algorithm takes into account the available bit rates and network delays of different networks. Based on the Beckmann transformation method, we obtain the threshold for the optimal traffic allocation. According to such a threshold, a minimal subset of admitted networks can be chosen and traffic allocation among these networks can be done to achieve the minimum delay. Simulation results show that the proposed algorithm could improve the arrival delay effectively and guarantee the maximum throughput under the heavy load condition.

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Low complexity transmit antenna selection algorithm for multi-cell interference alignment systems
ZHU Bin;GE Jianhua;SUN Chuiqiang;LI Jing
J4    2014, 41 (2): 9-14.   DOI: 10.3969/j.issn.1001-2400.2014.02.002
Abstract864)      PDF(pc) (554KB)(885)       Save

Starting from the investigation of the optimal transmit antenna selection (TAS) algorithm based on the exhaustive search and distributed interference alignment (IA), a low complexity TAS algorithm is proposed for multi-cell IA systems. The proposed algorithm utilizes the greedy search strategy and the distributed IA with partial iterations to reduce the computational complexity. In the proposed algorithm, the TAS scheme for each base station is optimized successively in a way that the system sum capacity is increased under the condition that the TAS schemes for the other base stations remain unchanged. Complexity analysis and simulation results show that the proposed algorithm can sharply reduce the computational complexity while the performance of system sum capacity is close to that of the optimal TAS algorithm. Moreover, by properly choosing the iteration number of partial iterations, the proposed algorithm can achieve an effective tradeoff between system sum capacity and computational complexity.

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Cited: Baidu(4)
Attack method against the McEliece cryptosystem based on the correlative quasic-cyclic codes set
LIU Jingmei;WANG Yanli;LIANG Bin;ZHAO Senlin
J4    2014, 41 (2): 15-19+50.   DOI: 10.3969/j.issn.1001-2400.2014.02.003
Abstract802)      PDF(pc) (476KB)(772)       Save

Focusing on the security of McEliece public key cryptosystem based on the QC-LDPC code, a new attack algorithm based on the correlative quasi-cyclic(QC) code word is proposed. As the code word in the QC code set is shifted cyclically which is equivalent to information retransmission, the algorithm's effect is better. Performance is analyzed from probability of the correct decipher and computational complexity. Simulation results show that the proposed algorithm possesses a higher probability of the correct decipher (0.999) and a lower work factor (240.7).

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Proxy re-signature scheme over the lattice
JIANG Mingming;HU Yupu;WANG Baocang;LIU Zhenhua;LAI Qiqi
J4    2014, 41 (2): 20-24.   DOI: 10.3969/j.issn.1001-2400.2014.02.004
Abstract1086)      PDF(pc) (447KB)(875)       Save

For the proxy insecurity of the re-signature schemes based on large integer factorization and the discrete logarithm problem in quantum environment, we present a proxy re-signature scheme that can resist the quantum attack. Using Xagawa's proxy re-encryption technology and lattice signatures without trapdoors technology, we construct the first lattice-based proxy re-signature scheme. The security of this scheme is based on the hardness of the Small Integer Solution(SIS) problem. The results of the proof and efficiency analysis show that this scheme has the properties of bidirection, multi-use, optimal key and transparency. Compared with previous schemes relying on other hardness assumptions, it has the advantage of low asymptotic computational complexity. Finally, we extend the scheme to the identity-based proxy re-signature scheme.

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Cited: Baidu(2)
Coherence-weighted optimum interferometric phase filtering method
LI Jinwei;LI Zhenfang;LIU Yanyang;BAO Zheng
J4    2014, 41 (2): 25-31.   DOI: 10.3969/j.issn.1001-2400.2014.02.005
Abstract908)      PDF(pc) (8746KB)(709)       Save

A coherence-weighted optimum interferometric phase filtering method is presented. It is proved that the optimum weight is the variance reciprocal of the phase noise in the sense of minimum post-filter phase noise variance, and the approach to obtaining the optimum weight through coherence estimation is exhibited. Moreover, in estimating the coherence, the synthetic interferogram of the scene which is proportional to the range difference between targets and radars is computed and compensated with reference DEM firstly, then a group of directional windows is utilized to select the samples adaptively according to the Minimum-Mean-Phase-Difference rule, and simulation experiment has established the reasonable choice of the directional windows' parameters. Finally, the processing results of the real data show that our method can suppress the phase noise and reduce the number of residues dramatically.

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Cited: Baidu(2)
Waveform de-correlation method in bistatic MIMO radars
DANG Bo;LIAO Guisheng;LI Jun
J4    2014, 41 (2): 32-36+78.   DOI: 10.3969/j.issn.1001-2400.2014.02.006
Abstract805)      PDF(pc) (584KB)(871)       Save

The auto-correlation and cross-correlation properties of transmit waveforms have great effects on the performance of MIMO radar systems. However, it is difficult to design waveforms that have ideal auto-correlation properties as well as cross-correlation ones. In this paper, an MMSE based waveform de-correlation algorithm is proposed to cancel the effects of the auto-correlation and cross-correlation of transmit waveforms in the receiver. The received signal model of bistatic MIMO radars is first derived. Then, the de-correlation filters are derived by using the MMSE method to reduce the influences of colored noise enhancement. Finally, the polynomial expansion method is used to simplify the computational complexity of the proposed de-correlation filters. The performance of the proposed method is verified by applying it to bistatic MIMO radar multi-target localization. Simulation results demonstrate the effectiveness of the proposed algorithm.

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Cited: Baidu(1)
High precision stitching algorithm for the DBS image
CHEN Hongmeng;LI Ming;JIA Lu;WU Yan
J4    2014, 41 (2): 37-43.   DOI: 10.3969/j.issn.1001-2400.2014.02.007
Abstract829)      PDF(pc) (2175KB)(1683)       Save

The stitching quality of the Doppler Beam Sharpening (DBS) image will be greatly affected due to the non-ideal movement of the radar platform (variation in attitude and  position). This paper presents a correction model for the movement error. A novel method based on affine transformation is proposed, which can correct and stitch the DBS image effectively. By compensating the variation in attitude and position simultaneously, the discontinuity could be eliminated. Subsequently, the sub-image is stitched together. Simulation analysis and measured data results show that the algorithm can correct the motion error and stitch the sub-images effectively without increasing the computational complexity.

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Analysis of the statistical model with the  two-dimensional cumulant feature applying to modulation classification
LIU Pei;SHUI Penglang;GUO Yongming;LI Ning
J4    2014, 41 (2): 44-50.   DOI: 10.3969/j.issn.1001-2400.2014.02.008
Abstract775)      PDF(pc) (568KB)(732)       Save

Higher order cumulants are the key features for implementing digital modulation classification. However, few available literatures focus on the statistical model of cumulant features. A two-dimensional normalized fourth-order cumulant feature is proposed to classify linear digital modulation in the additive white Gaussian noise channel, and then it is derived that the two-dimensional feature asymptotically obeys Gaussian distribution. In order to show the correctness of the proposition, a maximum likelihood classifier is formed in the two-dimensional feature domain according to the Bayesian criterion. The average probability of correct classification of the binary class problem is theoretically determined, which is consistent with the result obtained by simulations, thus justifying the correctness of the proposed theoretical results.

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