2011 Vol. 20, No. 4

Display Method:
A Hybrid Optimization Algorithm for the CMST Problem
HAN Jun, FANG Qingan, MAO Liyong, HUANG Yaling
2011, 20(4): 583-589.
Abstract(773) PDF(1731)
The Capacitated minimum spanning tree (CMST) problem is one of the most fundamental and significant problems in the optimal design of networks. It is also a classical combinatorial optimization problem which has been tackled by researchers for centuries using various methods. In this paper, a new NS-TS hybrid optimization algorithm that combines neighborhood search and tabu search is proposed. A novel neighborhood structure and associate tabu strategy is proposed and implemented. Computational experiments showing the effectiveness and efficiency of the algorithm on benchmark instances are given.
A VLSI Architecture for the Node of Wireless Image Sensor Network
ZHOU Renyan, LIU Leibo, YIN Shouyi, LUO Ao, CHEN Xinkai, WEI Shaojun
2011, 20(4): 590-596.
Abstract(514) PDF(1774)
This paper proposes a novel design of VLSI architecture for the node of wireless image sensor network. This architecture aims at the SoC (System on a chip) implementation and is composed of a general purpose embedded processor and several dedicated hardware accelerators for image processing and wireless communication. The hardware implemented Image processing unit (IPU) adopts an innovative image processing approach which concludes Bayer Color filter array (CFA) pre-processing and lossless JPEG compressing. The IPU can process 5 frames/s (VGA full color resolution) under a 16 MHz system clock, reaching a 2.6~4.7 bits/pixel compression rate with the PSNR larger than 46.3dB. The hardware implemented Wireless communication unit (WCU) executes computing intensive and timing critical tasks of the IEEE 802.15.4 Media access control (MAC) layer, which can achieve high performance and low power consumption on wireless operations compared of software implementation. Furthermore, low power design and techniques are employed to extend battery life, resulting in 45mW maximum system power consumption when the system is in the full working mode (i.e. processor, IPU and WCU are active simultaneously). The proposed architecture has been proto-typed on an FPGA system and fabricated in 0.18μm CMOS process.
Algorithm/Architecture Co-design of Edge Enhanced Compressed Domain Deblocking Filtering
ZHU Fang, WU Jianhui, SHI Longxing
2011, 20(4): 597-602.
Abstract(492) PDF(915)
This paper presents a new edge extraction based compressed domain deblocking algorithm and its ASIP (Application specific instruction processor) architecture for video decoding based on algorithm and architecture co-design methodology. Our algorithm works very stable and robust no mater under low bit rate compression or high bit rate compression scenarios. The VLIW (Very long instruction world) based ASIP implementation of our algorithm proves high performance with very limited hardware cost. The Algorithm and architecture co-design (AAC) concept is highly emphasized in this paper. We provide some quantitative example to show the necessity of algorithm and architecture co-design.
State/Action-based Fairness Verification for Non-determinism
XU Guangquan, PANG Shanchen, GAO Honghao, XIAO Yingyuan, LI Xiaohong, FENG Zhiyong
2011, 20(4): 603-606.
Abstract(510) PDF(696)
Most of the existing work about fairness verification was carried out by checking the fairness based on state, action, or process respectively. It is hard to resolve the fairness issue for complex software systems, especially in life-critical systems and safety-critical systems. In this paper, we verify the fairness based on both state and action, which is realized mainly by introducing an extended Kripke structure and four kinds of fairness (weak global/local fairness and strong global/local fairness). The experimental results show the superiority of our method by the savings in memory (2.08%) and time consumption (26.45%).
The Behavior Measurement Model of Trusted Network
LIU Xiangang, GONG Bei, ZHANG Xing, SHENG Changxiang
2011, 20(4): 607-611.
Abstract(516) PDF(874)
For lacking detailed behavior measurement in Trusted Network, current measurements are mainly based on identity and state measurement, in this paper the definition of network behavior and description of behavior adaptive to Trusted Network environment, and a new multi-dimensional behavior measurement model is presented. This model is based on several behavior prosperities such as individual similarity function, group similarity function, direct trust evaluation function, risk assessment function finishes trust measurement in many aspects, and is dynamic, fine-grained and adaptive to environment. It reduces the subjective factors of behavior measurement through the establishing of categorization weight of the behavioral prosperities by information entropy. The experimental results indicated that the model presented in this paper is more effective and environmental adaptable.
Simulation Study of Novel Very-Shallow-Trench-Isolation Vertical Bipolar Transistors on PD SOI
ZHOU Jianhua, S.K. PANG, ZOU Shichang
2011, 20(4): 612-616.
Abstract(422) PDF(1112)
Two new structures with Very-shallowtrench-isolation (VSTI) for vertical bipolar transistors on thin top-Si PD SOI are proposed and their characterization is studied by 2-D simulations. These bipolar structures are compatible with 0.13μm SOI-CMOS process. The two proposed transistors exhibit good device performance with current gain of 64.34 and 89.7, fT of 24.04GHz and 22.8GHz, fmax of 23.78GHz and 40.31GHz, respectively.
A Panchromatic Image-based Spectral Imagery Super Resolution Algorithm
WANG Suyu, ZHUO Li, LI Xiaoguang
2011, 20(4): 617-620.
Abstract(486) PDF(676)
A panchromatic image based spectral imagery super resolution algorithm is proposed to resolve the problem of remote sensing image resolution enhancement in this paper. A simple gray scale mapping method is first presented to better use high frequency details distilled from a high resolution reference panchromatic image, then a Maximum a posterior (MAP) based iterative optimization process is introduced to realize super resolution while keeping spectral characters. Evaluated by both simulated and really acquired images, the proposed method effectively improved the resolution of spectral imagery. PSNR (Peak signal to noise ratio) of the reconstructed images has improved 1~5dB compared with the traditional bilinear interpolation and IHS (Intensity hue saturation) based method. Subjective quality of the enhanced images has obviously exceeded the other twos as well.
Parallelizing Cryptographic Hash Function Using Relaxed Encryption Framework
GAN Xinbiao, WANG Zhiying, SHEN Li, LIU Cong, LAI Xin
2011, 20(4): 621-624.
Abstract(835) PDF(697)
With embarrass of high complexity of Cryptographic hash function (CHF) and difficulty of parallelizing CHF, a relaxed encryption framework for parallelizing CHF is proposed after understanding principle of hash value generation for CHF. In relaxed encryption framework, dependences in chain mode for generating hash value are broken so that it is possible to parallelize CHF fully, and the strength of encryption for relaxed framework is same as or stronger than that of standard CHF. Furthermore, a performance analytical model is presented to validate proposed framework.
Delay and Energy Analysis in Sparse Mobile Networks
WU Xiaojun, ZHU Xinjuan, XU Bo
2011, 20(4): 625-631.
Abstract(495) PDF(833)
In this paper, we describe the in-network processing of queries and answers, communication and mobility. We develop the analytical models to compute the system delay and the system energy consumption for P2P query processing schemes in sparse mobile networks. The analysis is based on Ordinary differential equations (ODE's) that describe the delay and energy consumption as a function of environmental parameters such as mobility, network density, and query selectivity. The analytical models enable users to choose the optimal paramers for a given environmental configuration. We validate our models in both walking and vehicular environment by simulations. The results of the simulations show good agreement with the predictions of the analytical models.
A Model for Dynamic Business Processes and Process Changes
PANG Shanchen, LI Yin, HE Hua, LIN Chuang
2011, 20(4): 632-636.
Abstract(465) PDF(1110)
In order to adapt to the inconstancy of business environments and service requirements, a model of dynamic workflow and its rewriting net are defined. Some good properties of the model and its rewriting net such as inheritability, reversibility, transitivity, and soundness are proved. In order to achieve programmable, structural, online and o2ine changes, their corresponding mechanisms are established. The model and mechanisms can be used to analyze and implement dynamic processes and process changes automatically. Process dynamics may depend on both structural and functional changes which constitute the two methods of process change deployment. This paper adopts a DPLW (Dynamic programmable logic workflow) model based on Petri nets to design and implement dynamic business processes. A prototype is given to demonstrate the proposed model and mechanisms to deal with process changes.
The Research of Optimal Motion Planning for Robot in Complex Environment
PIAO Songhao, ZHONG Qiubo, LIU Yaqi
2011, 20(4): 637-640.
Abstract(435) PDF(841)
A motion control system is designed for the biped robot walking up and down a slope. Firstly, model of robot walking on slope is present and kinematics equations of that motion are proposed. Secondly, the trajectories of foot and hip are parameterized, and other trajectories of joints are computed by the geometrical relationship when the robot executing those motions. Thirdly, a new improved particle swarm optimization is introduced to optimize the motion of robot under the constraint of dynamic movement in complex environment. The whole motion is controlled through two fuzzy logic controllers whose rules are optimized by improved particle swarm present in this paper off-line. Finally, experiments show the efficiency of the method in the paper.
Modeling Multi-Point Transport Protocol in P2P Networks
ZHAO Yongxiang, CHEN Changjia, ZHANG Baoxian
2011, 20(4): 641-645.
Abstract(520) PDF(708)
Congestion control mechanism is investigated under peer to peer application environment. A mathematical model is build to identify the relationships among the key parameters of the M2M transport control, leading to the following results: The downloading rate of a peer will be saturated with the increasing number of peers to download from when no time deadline is required; there exists an optimal number of peers to download from in order to maximize a peer's throughput when timeout mechanism is adopted. We conduct simulation experiments to validate our model.
Qualitative Analysis of Gene Regulatory Networks Based on Angular Discretization
WANG Xuesong, LIU Qingfeng, CHENG Yuhu, LI Lijing
2011, 20(4): 646-650.
Abstract(409) PDF(717)
It is well known that there is a hypothesis in the analysis of gene regulatory networks, i:e., if two genes expression profiles change in a similar trend, a regulatory relationship may exists in these two genes. Therefore, the use of angular discretization to deal with gene expression data can reflect the changes of gene expression values in tendency and intensity, which makes it possible to analyze the regulatory relationship between genes qualitatively. At first, we draw a line between the neighboring gene expression data. Thus an angle between the connected line and a horizontal line is formed. Secondly, according to the de- fined rules of angular discretization, we discretize the angle into six states by carrying out several times of discretization operation. The six states reflect not only the trend but also the change degree of gene expression values. In the end, the genes having regulatory relationships will be identified by using the substruction and the relative frequency methods. Experimental results concerning on the Saccharomyces microarray dataset verify the validity of the proposed method.
Potable Low-Intensity X-Ray Real-Time Imaging System and Its Application in Detection and Diagnosis
CHEN Li, LI Ye, QIN Xulei, WANG Xin, WU Kui, JIANG Delong, TIAN Jingquan
2011, 20(4): 651-654.
Abstract(410) PDF(1016)
The portable low-intensity x-ray real-time imaging system was composed of Lixiscope, the image collection and procession system of CCD. Recently, people pay more attention on it due to its wide applications. In this paper, the structure and characteristics of CsI/MCP photocathode was briefly given. The controllable main factors (image noise and aberration) which influence the imaging quality of the image tube (single single-proximity focusing x-ray image intensifier) were analyzed. The method to improve the image quality by decreasing the working voltage of MCP was proposed. At the same time, the other method such as cooling CCD, prolonging the integration time and image-processing were also studied. The optimized resolution (6.3lp/mm) was obtained which can achieve the anticipated goals to decrease the flashing noise and ensure the brightness of the image. Using this system, the industrial product, the finger of human body and so on can be detected and diagnosed. The corresponding pictures were given which indicating an wide applications of this new type of low-intensity x-ray real-time imaging system.
Pairing Computation on Elliptic Curves of Jacobi Quartic Form
WANG Hong, WANG Kunpeng, ZHANG Lijun, LI Bao
2011, 20(4): 655-661.
Abstract(475) PDF(1193)
This paper proposes explicit formulae for the addition step and doubling step in Miller's algorithm to compute Tate pairing on Jacobi quartic curves. We present a geometric interpretation of the group law on Jacobi quartic curves, which leads to formulae for Miller's algorithm. The doubling step formula is competitive with that for Weierstrass curves and Edwards curves. Moreover, by carefully choosing the coefficients, there exist quartic twists of Jacobi quartic curves from which pairing computation can benefit a lot. Finally, we provide some examples of supersingular and ordinary pairing friendly Jacobi quartic curves.
Point Pattern Matching Based on Spectra of Directed Graphs
LIANG Dong, ZHU Ming, FAN Yizheng, YAN Pu
2011, 20(4): 662-666.
Abstract(431) PDF(904)
We present a novel algorithm for point pattern matching by means of spectra of directed graphs. Given a feature point-set, we construct a weighted directed graph and skew-symmetric matrix associated with the graph. By using spectral decomposition of the matrix, we give a spectral representation of the feature points with half of the eigenvectors. We theoretically analyze that our method can well deal with the matching problem under affine transformation. The expreiments applied to synthetic data and real-world images show the effectiveness of our method.
A Resource-efficient Load Balancing Algorithm for Network Virtualization
LIAO Shengquan, WU Chunming, YANG Qiang, WANG Baojin, JIANG Ming
2011, 20(4): 667-670.
Abstract(451) PDF(871)
Most recently much effort has been made to address Internet "ossification" by exploiting network virtualization technique. It allows multiple virtual networks to share the physical substrate for delivering customized services via heterogenous protocols or mechanisms. Recent advances enable virtual routers to flexibly migrate across multiple physical routers without interrupting network operation. With this recognition, this paper takes a further step by proposing a novel algorithmic approach to optimize network load balancing as well as resource utilization. The suggested approach is assessed through extensive simulation experiments against two other algorithmic solutions for a range of network scenarios (e:g. dense and sparse networks). The numerical result shows its effectiveness in providing the best trade-off of network load balancing and resource utilization whilst minimizing the communication overheads.
A Statistical Two-step Method for 3D Face Reconstruction from a Single Image
GONG Xun, WANG Guoyin, LI Xinxin, LI Tianrui
2011, 20(4): 671-675.
Abstract(460) PDF(785)
To make computer recognize well about the facial shape, we propose a Two-step face modeling (TSFM) scheme to make use of prior knowledge of facial shape learnt from a large scale 3D face database. At first, the depth of features is estimated. Then we apply the estimated 3D features to a novel dynamic components deformation model to build a more precise facial shape for a given image. Test results on synthesized images with the known ground truth show that the TSFM scheme is both robust and accurate in facial shape reconstruction.
NLFM Interference Suppressing Based on Time-Varying AR Modeling and Adaptive IIR Notch Filter
FENG Jining, YANG Xiaobo, DIAO Zhejun, GONG Wenfei, WU Siliang
2011, 20(4): 676-680.
Abstract(410) PDF(1251)
Uing TVAR (Time varying AR) model and adaptive notch filter is a new method for the nonstationary jammer suppression in DSSS (Direct sequence spread spectrum). The performance of TVAR model for IF (Instantaneous frequency) estimation will be affected by some factors such as basis functions. Focusing on this problem, the optimal basis function of TVAR model for the IF estimation of the NLFM signal is obtained in this paper. Besides the depth and width of notching, the phase properties of notch filter affect the SINR of correlation output to the narrow band jammer suppression in DSSS, in response to the problem the closed solution of correlation output SINR improvement has been derived when a single frequency jammer passes through direct IIR notch filter, and its performance has been compared with those of five coefficient FIR filters. Later, a novel method for NLFM jammer suppression based on Fourier basis TVAR model and direct IIR notch filter is proposed. The simulation results show the effectiveness of the proposed method.
A Similar-Curve Based Auto-sorting Algorithm for Panoramic Images
XIANG Yao, LONG Haixia, ZOU Beiji, MENG Zhigang
2011, 20(4): 681-685.
Abstract(374) PDF(883)
A sorting algorithm using similar-curve is proposed to automatically rearrange the input images in order, which is usually taken as a preprocessing step for mosaicing panoramic image. First, the similar curve of each input image is computed, and then, with the proposed quick match strategy, the similarities between any two images are calculated to construct a similarity matrix. By analyzing the similar curves and the similarity matrix, whether the input images should be sorted horizontally or vertically is judged and the images are automatically sorted in order along the judged direction. Experimental results demonstrate the effectivity of the proposed algorithm.
A Novel Cyclic-Moment Based Method for DS-SS QPSK Signal Blind Parameter Estimation
JIN Yan, JI Hongbing
2011, 20(4): 686-690.
Abstract(448) PDF(1037)
The parameter estimation of Direct sequence spread spectrum (DS-SS) signals with QPSK modulation under non-cooperative conditions is considered. The explicit expressions of both the third- and the fourthorder cyclic-moments of QPSK signals are derived, and the cycle frequency structure corresponding to the secondand fourth-order cyclic-moment of DS-SS (Direct sequence spread spectrum) QPSK signals is deduced. A novel parameter estimation method is proposed by combining the second- and the fourth-order cyclic-moments, which can perform blind parameter estimation without a priori knowledge of pseudorandom sequence and frequency parameters. Moreover, the method which employs onedimensional slices, also avoids multi-dimensional searching. Simulation results are presented to confirm the validity of the method.
Flexible Threshold Proxy Re-signature Schemes
YANG Xiaodong, WANG Caifen, LAN Caihui, WANG Biao
2011, 20(4): 691-696.
Abstract(541) PDF(931)
Threshold proxy re-signatures are extensions of proxy re-signatures where re-signature keys are shared among n proxies in such a way that at least k out of n proxies must collaborate to generate the delegator's signatures. The adversary must compromise at least k proxies to learn the re-signing key. Threshold proxy re-signature can protect re-signature key from the attack of internal and external adversaries. However, threshold values in previous threshold proxy re-signatures are fixed. Two flexible threshold proxy re-signature schemes are proposed in this paper, which are existentially unforgeable and robust in the standard model. Based on the Chinese Remainder Theorem, threshold value and the number of proxies can be altered with the significance of the document to be signed. According to the variable threshold value, each proxy can locally generate his re-signature key share and the corresponding verification key. Meanwhile, the proxy re-signature share generation and verification algorithms are non-interactive.
Research of Root Sum of the Square Criterion in Pulse Transition Duration Metrology
ZHU Jiangmiao, GUO Kai, LIU Mingliang, LI Ran
2011, 20(4): 697-700.
Abstract(423) PDF(813)
The Root sum of the square criterion (RSS criterion) is general accepted rule in pulse signal metrology and oscilloscope calibration. But the RSS criterion has a premise that the system should be two cascaded Gaussian system, otherwise the error is unacceptable. The paper derived the RSS criterion from the basic principle of measuring the pulse resource by oscilloscope or measuring the oscilloscope by resource. On the other hand, the characteristic of modern oscilloscope deviates Gaussian system greatly, and the premise of RSS are not satisfied anymore. The simulation and experiment data in the paper verified the premise of the RSS and indicated that the measurement result was unacceptable when the premise is not satisfied. The paper derived deconvolution algorithm in signal reconstruction and system identification to realize the metrology of the pulse signal and calibration of the oscilloscope.
Ultralightweight RFID Authentication Protocol Based on Random Partitions of Pseudorandom Identifier and Pre-shared Secret Value
NING Huansheng, LIU Hong, YANG Chen
2011, 20(4): 701-707.
Abstract(563) PDF(1854)
As open and wireless RFID air interfaces suffer from severe threats, concerns with respect to the security and privacy problems are increasingly becoming noteworthy issues. The paper proposes an ultralightweight RFID authentication protocol based on Random partition (RPAP) to achieve security and efficiency. The protocol adopts multiple mechanisms (i:e. random partition, dynamic update, and mutual authentication) as safeguards in the air interface. Specifically, random partition mechanism is used to divide the pseudorandom identifier and pre-shared secret value for bitwise operations; dynamic update mechanism enhances the freshness during identifi- cations; double-entity-round mutual authentication mechanism provides stratified access control. Meanwhile, attack models are established to analyze the resistance to typical attacks (i.e. replay, spoofing, tracking, and tampering) in the primary and further authentication. Furthermore, security and performance are analyzed to prove that the protocol owns high security, high efficiency, and low complexity. The protocol is practical for the low-cost and resource-limited RFID applications.
An Enhanced EM/SAGE-based H-infinity Channel Estimator for MIMO-OFDM Systems
XU Peng, WANG Jinkuan, QI Feng, SONG Xin
2011, 20(4): 708-712.
Abstract(463) PDF(809)
This paper proposes a low-complexity and robust H-infinity channel estimator for Multiple-input multiple-output (MIMO) Orthogonal frequency division multiplexing (OFDM) systems. To lessen the complexity, the Expectation maximization (EM) and Space-alternating generalized EM (SAGE) algorithms are adopted respectively. To treat with the effect of Non-Gaussian noise (NGN) channels, an Equivalent signal model (ESM) is used to enhance the robust of the EM-type H-infinity estimator. Furthermore, joint estimation using Phase shifted orthogonal (PSO) pilot sequences is applied for improving the estimation and the requirement for pilot. Simulation results show that the H-infinity estimator has almost the same Mean square error (MSE) as Maximum a posteriori (MAP) estimator. By using the ESM, the robustness of EM-type based H-infinity estimator is enhanced against NGN channels. In addition, the MSE and pilot overhead are reduced by applying the joint estimation with PSO.
Max-flow Capacity for Multi-hop Mobile Wireless Networks
SHI Yan, SHENG Min, LI Jiandong, ZHANG Wenbin
2011, 20(4): 713-718.
Abstract(413) PDF(740)
In this paper, the mobility of multi-hop wireless networks is considered as a key factor influencing max-flow capacity, and a new unified analytical expression of the maximum flow capacity of a mobile wireless network is derived under mobility models. The simulation results under different mobility models, including random waypoint, random walk, and random direction, show that the max-flow capacity of mobile wireless networks still exhibits a concentration behavior around the mean value of the minimum cut, which is less than the expected number of the neighbors of the network.
A Novel MLT-based ETF-OFDM System for Anti-Jamming Communications
SHANG Yong, FENG Xiaotao
2011, 20(4): 719-724.
Abstract(424) PDF(812)
Previous research has shown that the Expanded time-frequency OFDM (ETF-OFDM) system has good performance in anti-jamming communication. In this paper, a novel Lapped transform-based ETFOFDM system is proposed with respect to the wideband anti-jamming communication. The OFDM modulation/demodulation of the proposed system are accomplished by using Inverse modulated lapped transform (IMLT)/Modulated lapped transform (MLT) instead of Inverse discrete Fourier transform (IDFT)/Discrete Fourier transform (DFT), respectively. Compared to DFT, the basis functions of MLT have better stop-band attenuation. Benefit from this, the new system could achieve better anti-jamming performance than the ETF-OFDM system based on DFT in both without/with frequency schedule case. Simulation results show that the proposed system has better spectrum utilization and more robust anti-jamming performance than the conventional DFT-based system.
Performance Analysis for Intrusion Target Detection in Wireless Sensor Networks
FAN Gaojuan, WANG Ruchuan, HUANG Haiping, SUN Lijuan, XIAO Fu
2011, 20(4): 725-729.
Abstract(479) PDF(1420)
Target detection and field surveillance are among the most prominent applications of wireless sensor networks. The quality of detection achieved by a sensor network can be quantified by evaluating the probability of detecting a mobile target crossing a sensing field. Detection probability of sensor nodes has been studied in sensor networks for many purposes such as quality of service and decision making. However, the sensing capabilities of sensors are affected by environmental factors in real deployment. This paper investigates the problem of detecting probability in a log-normal shadow fading environment. It presents an analytic method to evaluate the detection probability by at least k sensors under practical considerations. Furthermore, we also shows that shadow fading makes significant influence in detection probability compared to unit disk sensing model through extensive simulation experiments.
A Typical Network Covert Timing Channel with Uniformly Distributed Noise
LIU Xiong, DAI Yiqi
2011, 20(4): 730-734.
Abstract(413) PDF(614)
Adding noise to the covert timing channel is an important method to decrease the covert channel's capacity. Most works are focus on the first in first out queuing for service mechanism, but the mechanism restricts the network packet transfer rate. This paper analyzes the network covert timing channel with artificial noise which is uniformly distributed. The mechanism of adding noise is not queuing, and it doesn't restrict the network packet transfer rate. Paper gets a series formulas to calculate the channel's capacity, and calculates the channel's capacity in some special situations. The analysis shows the relationship between the noise intensity and the channel's capacity. To verify the correctness of the theory analysis, paper constructs such a network covert timing channel, and the channel's communication performance is in accord with the theory analysis.
Jammer Localization for Wireless Sensor Networks
SUN Yanqiang, WANG Xiaodong, ZHOU Xingming
2011, 20(4): 735-738.
Abstract(459) PDF(1240)
Jamming attack can severely affect the performance of Wireless sensor networks (WSNs) due to the broadcast nature of wireless medium. In order to localize the source of the attacker, we in this paper propose a jammer localization algorithm named as Minimum-circlecovering based localization (MCCL). Comparing with the existing solutions that rely on the wireless propagation parameters, MCCL only depends on the location information of sensor nodes at the border of the jammed region. MCCL uses the plane geometry knowledge, especially the minimum circle covering technique, to form an approximate jammed region, and hence the center of the jammed region is treated as the estimated position of the jammer. Simulation results showed that MCCL is able to achieve higher accuracy than other existing solutions in terms of jammer's transmission range and sensitivity to nodes' density.
DFCM: A Distributed Floor Control Mechanism in PoC
LIAO Jianxin, LIU Haipeng, LI Tonghong, WANG Jingyu, ZHU Xiaomin
2011, 20(4): 739-746.
Abstract(425) PDF(857)
With the fast progress of Collaborative multimedia application (CMA) running on overlay network, Push to talk over cellular (PoC) attracts signifi- cant interest in the field of mobile cellular communications. PoC is an on-demand, resource efficient, half-duplex multimedia service. Due to the half-duplex nature, only one user is allowed to speak at a time, and the others listen. If listeners want to speak, they have to contend for the right to speak and wait for the permission if request waiting is supported. Open mobile alliance (OMA) proposed a centralized controlling based floor control mechanism for speak right coordination in PoC, which is called Talk burst control protocol (TBCP). But it has many limitations in scalability, reliability and robustness as all centralized approaches have. In addition, none of available distributed approaches well meets mobile users' requirements in PoC, especially for the request waiting function. In this paper we put forward a novel distributed floor control mechanism with request waiting for PoC, which is called Distributed floor control mechanism (DFCM). From the performance evaluation of DFCM and TBCP, we find that DFCM outperforms TBCP especially when performance of the central node, Controlling server (CS), drops down due to heavy load. Finally, this paper is summarized and future work is forecasted.
Spectral Analysis of Two Boolean Functions and Their Derivatives
ZHUO Zepeng, CHONG Jinfeng, CAO Hao, XIAO Guozhen
2011, 20(4): 747-749.
Abstract(458) PDF(846)
The relationship between the spectrums of two arbitrary Boolean functions and the spectrum of their derivatives is presented by using Convolution Theorem. Also, we deduce the relationship between the Walsh spectrums and the decompositions of two arbitrary Boolean functions in this paper. Based on them, we generalize some properties between the Walsh spectrum and the crosscorrelation function.
A Novel Decision-level Fusion Segmentation Approach of SAR and Optical Images
XU Huaping, WANG Wei, LIU Xianghua
2011, 20(4): 750-754.
Abstract(443) PDF(817)
A novel decision-level fusion segmentation approach of two Synthetic aperture radar (SAR) images and one optical image is presented. First, the energy function for optimal segmentation of two SAR images is deduced and fusion segmentation approach based on the Markov random field (MRF) model for SAR images is proposed. Then, an optical image is employed to further improve the segmentation performance and accelerate the segmentation process of two SAR images. By using of optical image classification, the image pixels are classified into three classes: certain target pixels, certain background pixels and uncertain pixels, respectively. The certain pixels' labels are maintained as their ultimate segmentation labels. Only the uncertain pixels need to be segmented by SAR fusion segmentation method based on the MRF model. Finally, a fast annealing strategy is proposed to accelerate the fusion segmentation process of uncertain pixels. Results of computer simulation validate the effectiveness of the proposed method.
Parallel Genetic Unscented Particle Filter Algorithm
CONG Li, QIN Honglei
2011, 20(4): 755-760.
Abstract(441) PDF(997)
For Particle filter (PF) has the problem of degeneracy phenomenon, this paper effectively integrates Parallel genetic algorithms (PGAs) and Unscented particle filter (UPF), and puts forward the Parallel genetic unscented particle filter (PGUPF) based on distributed algorithm structure. This method divides all particles into several subpopulations to parallel execute particle filtering. Based on importance density optimization by Unscented Kalman filter (UKF), several genetic operators such as crossover, mutation, selection and migration are adopted to optimize importance sampling and resampling processes, which can not only move particles fast to the region of high likelihood, but also increase particles diversity. It gives full play to the characteristic of parallelization of PF, and decreases computation amount of the filtering algorithm. By theoretical analysis and software simulation, PGUPF is compared with several existed PF algorithms in the estimation accuracy and computation efficiency for satellite navigation and positioning, and the effectiveness of PGUPF has been verified.
Rao Test Design for MIMO Radar in Non-Gaussian Clutter
ZHU Xiaobo, WANG Shouyong
2011, 20(4): 761-765.
Abstract(400) PDF(734)
This paper mainly deals with the problem of Multiple-input multiple-output (MIMO) radar in non-Gaussian clutter modeled as a complex isotropic Symmetric α-stable (SαS) process. The widely separated MIMO radar or Statistical MIMO (S-MIMO) radar is adopted. First, the signal model is developed to the complex isotropic SαS clutter, and then, the S-MIMO Rao detector is derived. To demonstrate the efficiency of the new detector, its performance is compared to that of the well-known Optimum Gaussian (OG) detector of S-MIMO Radar. Monte Carlo simulations are given for the cases of different clutter parameters and transmit/receive antennas. Via several numerical examples, it is shown that the S-MIMO Rao detector can provide excellent detection performance in heavy-tailed clutter compared with the S-MIMO OG detector.
Research on Generalized Simulation of Aerospace TT & C Channel Based on Equal Interval Sampling-unequal Interval Reconstruction
ZHENG Zhe, WU Siliang, ZHOU Yang
2011, 20(4): 766-768.
Abstract(359) PDF(552)
In order to obtain generalized simulation of Aerospace tracking, telemetry and control (Aerospace TT & C) channel, a simulation method based on equal interval sampling -unequal interval reconstruction is put forward in this paper. The method samples the input signal of the uplink and downlink at stated intervals, releases the sampled date by unequal interval clock which is based on the variation rule of the satellite-to-earth location, and then acquires the simulation signals by reconstruction filter. Comparing with existing methods, the method can be used in any working modes and systems. It can simulate the transmission effect of electromagnetic wave in the channel without knowing priori knowledge, such as the carrier frequency, code pattern, code rate, and so on. The theory and the arithmetic of the generalized simulation method and unequal interval clock generation will be analyzed in this paper.
A New Deramp-NECS Imaging Algorithm for Missile-Borne Hybrid SAR
XU Huaping, ZHU Yadi, KANG Changhui, ZHOU Yinqing
2011, 20(4): 769-774.
Abstract(396) PDF(1482)
A new imaging method, Deramp-nonlinear extended chirp scaling (Deramp-NECS) algorithm, was proposed for high resolution squint missile-borne hybrid Synthetic aperture radar (SAR) in high speed dive trajectory. The hybridization degree of missile-borne hybrid SAR in dive trajectory was redefined. Then the equivalent range model and the expressions of echo signals were presented. By analyzing the missile-borne hybrid SAR echo signal, it was presented that the cubic-order phase item existed and had to be compensated. Deramp-NECS algorithm was put forward to implement the missile-borne hybrid SAR imaging. It firstly solves the azimuth spectrum aliasing using deramp processing with constant Doppler frequency modulation rate to realize the coarse focusing in azimuth. Then the improved CS principle introducing non-linear frequency compensation is used to get the fine focusing in range, while the azimuth errors caused by deramp processing are also compensated to realize the fine focusing in azimuth. Finally, computer simulation is employed to validate the availability.