2013 Vol.31

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Demodulation and Mapping Scheme for 2FSK Two-Way Relay Communication Systems with Physical-Layer Network Coding LI Bo, WANG Gang, YANG Hong-juan, ZHENG Da-guo, ZHANG Xiao-dong Journal of Applied Sciences    2013, 31 (1): 1-6.   DOI: 10.3969/j.issn.0255-8297.2013.01.001 Abstract （2019）      PDF（pc） （1244KB）（1097）       Knowledge map    Save A correlative demodulation and mapping scheme is proposed for the relay nodes in 2FSK two-way relay communication systems. The scheme ses superimposed signals with two branches, and samples the discrepancy to make a decision, which may be mapped to a binary bit. The decision thresholds are calculated according to the maximum posterior probability criterion. The relay nodes’ decision error probability and the bit error rate of the entire system are analyzed. Theoretical analysis and simulation results show that the relay nodes’ decision error probability and the system BER of the physical-layer network coding scheme using the proposed demodulation and mapping method are close to those of the traditional scheme and the network coding scheme, but the throughput is higher than the two. Related Articles | Metrics | Comments（0） Cited: Baidu(6)

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Diversity Performance of Multi-source Multi-relay Cooperative System with Linear Network Coding ZHANG Hai-chao, LI Hui, DAI Xu-chu, Journal of Applied Sciences    2013, 31 (1): 7-14.   DOI: 10.3969/j.issn.0255-8297.2013.01.002 Abstract （1903）      PDF（pc） （1158KB）（1169）       Knowledge map    Save To design a linear network code and increase diversity gain of multi-source multi-relay system, this paper investigates relationship between diversity gain and minimum hamming distance of network code, and proposes a method that using minimum hamming distance as the design criterion of linear network code. By using related theories and methods of classic linear block code, an important proposition that system diversity gain is equal to minimum hamming distance is derived. Based on this proposition, the original problem of designing network code is converted to designing classic linear block codes under minimum hamming distance criterion. In addition, based on the singleton bound in the classic coding theory, quantitative relationship between maximum diversity and relay number is obtained. Simulation results show that the diversity gain is improved by increasing the minimum hamming distance and the maximum diversity gain is equal to the total number of relays plus 1. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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TPSN Time Synchronization Protocol Based on Pulse Coupling SHI Chao1, QIU Hong-bing1,2 Journal of Applied Sciences    2013, 31 (1): 15-20.   DOI: 10.3969/j.issn.0255-8297.2013.01.003 Abstract （1532）      PDF（pc） （1769KB）（1410）       Knowledge map    Save In view of the disadvantage of the traditional timing sync protocol for sensor networks (TPSN), a pulse-coupled time synchronization protocol for sensor networks (P_TPSN) is proposed. P_TPSN is a noninteractive time synchronization scheme based on pulse-coupled synchronization for distributed networks. A network topology is built to ensure that the time information of net nodes of previous hierarchy can be received by the net nodes of posterior hierarchy. After receiving these time information, the net nodes of posterior hierarchy will adjust their time clocks respectively by weighted average of the received time information. This scheme can enhance robustness of distributed wireless networks and has good scalability and quick convergence. Theoretical analysis and simulation results show that the proposed scheme is effective and feasible.  Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Improvement of Admission Selection for Heterogeneous Wireless Networks SHI Wen-xiao, LI Na, WANG Ji-hong Journal of Applied Sciences    2013, 31 (1): 21-26.   DOI: 10.3969/j.issn.0255-8297.2013.01.004 Abstract （1705）      PDF（pc） （8066KB）（1286）       Knowledge map    Save Abstract: For all IP services, we propose an improved alterable transmission units-based admission selection algorithm in LTE/WiMAX integrated heterogeneous wireless networks. The algorithm uses two-dimensional resource units to calculate system capacity. By introducing load transfer and alterable transmission units,system resources are distributed more reasonably, making the system more effective in serving all IP business. The algorithm uses the queuing theory to establish a four-dimensional Markov queuing model, and analyze and evaluate the system performance. Simulation results show that, compared with the original admission selection algorithm, the proposed algorithm suits actual networks better, and can significantly reduce blocking rate of non-realtime services and increase the overall resource utilization of the system without affecting the realtime service performance. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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SER Analysis for High-Order Modulated Physical Layer Network Coding over AWGN Channels LI Dan-dan1, XIONG Ke1,2, DU Guan-yao1, ZHANG Yu1, QIU Zheng-ding1 Journal of Applied Sciences    2013, 31 (1): 27-33.   DOI: 10.3969/j.issn.0255-8297.2013.01.005 Abstract （2061）      PDF（pc） （7867KB）（1379）       Knowledge map    Save We extend the nearest neighbor approximation method and investigate the symbol error rate (SER) over AWGN channels for physical layer network coding with high order modulation. We derive a closed-form expression of PNC’s SER with 8PSK modulation over AWGN channels. We find that, when the power of one source node is fixed, SER of PNC does not monotonously decrease with the increase of the power of the other source node. Simulation results show that the derived SER expression can characterize the SER performance of PNC’s SER with 8PSK modulation over AWGN channels. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Adaptive Feedback Bit Allocation in Distributed Multi-cell Joint Transmission ZHAI Xu-ming, QIU Ling Journal of Applied Sciences    2013, 31 (1): 34-40.   DOI: 10.3969/j.issn.0255-8297.2013.01.006 Abstract （2389）      PDF（pc） （5154KB）（1439）       Knowledge map    Save In this paper, we propose an adaptive feedback bit allocation strategy for distributed multi-cell pre-coding systems with limited feedback. By analyzing the rate loss of multi-cell joint transmission caused by limited feedback, we provide an approximate upper bound as a function of allocated feedback bit for each channel. Based on this rate loss, an adaptive feedback bit allocation strategy is proposed. The strategy effectively reduces the rate loss due to limited feedback, and thus significantly increases the system rate. Without additional periodical feedback and heavy computation overhead, the proposed strategy is feasible in real systems. Good performance has been shown in simulation. Related Articles | Metrics | Comments（0）

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Performance Analysis Model for IEEE 802.11 Distributed Coordination Function Protocol ZHONG Ping, SHI Hai-bin, ZHUANG Yu-xiang, SHI Jiang-hong, CHEN Hui-huang Journal of Applied Sciences    2013, 31 (1): 41-47.   DOI: 10.3969/j.issn.0255-8297.2013.01.007 Abstract （2011）      PDF（pc） （4412KB）（2291）       Knowledge map    Save This paper proposes an improved two-dimensional Markov chain model for the performance analysis of the IEEE 802.11 DCF protocol. The model is applicable to both saturated and unsaturated traffic conditions. Moreover, it extends the existing models to take into account previously-ignored MAC layer factors such as backoff freezing and limited times of retry. In addition, by deriving the stationary state of the Markov model and considering an M/M/1/K queuing model, we further derive a theoretical model for evaluating performance of the general IEEE 802.11 DCF protocols. Accuracy of the proposed theoretical model is validated with simulation results. Related Articles | Metrics | Comments（0） Cited: Baidu(5)

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RS Coded EBPSK-MODEM Based on SVM Discrimination JIN Yi, WU Le-nan, YING Peng-kui, YU Jing Journal of Applied Sciences    2013, 31 (1): 48-52.   DOI: 10.3969/j.issn.0255-8297.2013.01.008 Abstract （2131）      PDF（pc） （8129KB）（1600）       Knowledge map    Save Impacting filter can change phase jump of the extended binary phase shift keying (EBPSK) signal into magnitude impact so as to enlarge the difference between waveforms of 0 and 1. To take full advantage of the special filtering mechanism, we design an RS coded EBPSK-MODEM based on the support vector machine (SVM) discrimination. After briefly describing the principle of EBPSK modem, an EBPSK detector model based on SVM is proposed, which uses the classification ability of SVM. Performances of binary phase shift keying (BPSK) and EBPSK are compared, and an RS coded EBPSK modem based on SVM is designed. Simulation results show that, taking bit·s−1/Hz/SNR as an aggregate indicator, EBPSK system outperforms BPSK, and, compared with the RS coded EBPSK modem based on adaptive threshold decision, the proposed SVM-based method can obtain about 1 dB coding gain in AWGN channel at BER of 10−4. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Multi-target Localization for Bistatic MIMO Radar CHENG Yuan-bing, GU Hong, SU Wei-min Journal of Applied Sciences    2013, 31 (1): 53-58.   DOI: 10.3969/j.issn.0255-8297.2013.01.009 Abstract （1802）      PDF（pc） （6318KB）（1360）       Knowledge map    Save To solve the target localization problem in a bistatic multiple-input multiple-output (MIMO) radar, a method based on upper-triangularization of the joint matrix is proposed to estimate the direction of departure (DOD) and direction of arrival (DOA). The angle estimation is first transformed to a joint-matrix upper-triangularization problem. The extended QZ iteration algorithm is then used to solve the problem. The steering matrices of transmission and receiving are estimated. Thus, the DOD and DOA are recovered by spectrum analysis. The proposed method uses the full information in the matched filter output without the need of two-dimensional search for the spectral peaks. It produces an accurate closed form solution in each iteration. Compared with the existent approaches, the proposed method provides better angle estimation accuracy with the DOD and DOA automatically paired. Effectiveness of the method is shown in simulation. Related Articles | Metrics | Comments（0）

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Performance Analysis of Equal Gain Diversity over Correlated Nakagami Fading Channels ZHU Qiu-ming, XU Da-zhuan, Lü Wei-hua, CHEN Xiao-min, MENG Tian-zhen, REN Jia-min Journal of Applied Sciences    2013, 31 (1): 59-64.   DOI: 10.3969/j.issn.0255-8297.2013.01.010 Abstract （1662）      PDF（pc） （6445KB）（947）       Knowledge map    Save Since performance of equal gain combination (EGC) over correlated Nakagami fading channels does not have exact closed-form expressions, efficient approximation based on moment matching is proposed in this paper. We approximate the superposed fading distribution of EGC output by a new −μ distribution. Thus the system performances can easily be obtained with the aid of stochastic properties of the −μ random variable. The performances include signal-to-noise ratio (SNR) distribution, outage probability and average error ratio (SER). The method is easy to implement, and the simulation results match the theoretical ones very well. It can be applied to parameter design and performance evaluation of EGC system over various fading channels. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Source Number Estimation by Delay Correlation Preprocessing SI Wei-jian1, LIN Qing-qing1, PENG Jie2 Journal of Applied Sciences    2013, 31 (1): 65-71.   DOI: 10.3969/j.issn.0255-8297.2013.01.011 Abstract （1571）      PDF（pc） （2990KB）（1092）       Knowledge map    Save Source number estimation based on information theoretic criteria is ineffective in colored noise field, and the performance of the Gerschgorin radii algorithm may decline under low signal-to-noise ratio conditions. To solve these problems, a method of source number estimation using delay correlation preprocessing is proposed. The delay correlation matrix of all received data is calculated to reduce the influence of noise on the estimation performance. The eigenvectors are then grouped according to the grouping rules so that different kinds of characteristic spaces can be obtained, one containing noise eigenvectors and the other containing both noise and signal eigenvectors. Finally, the delay correlation matrix is projected onto the characteristic spaces, and thus the source number can be estimated from the projected data. Simulation and measured data show correctness and effectiveness of the algorithm. Related Articles | Metrics | Comments（0）

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Distance-Preserving Color Visualization Model for Hyperspectral Imagery WANG Li-guo, LIU Dan-feng, ZHAO Liang Journal of Applied Sciences    2013, 31 (1): 72-78.   DOI: 10.3969/j.issn.0255-8297.2013.01.012 Abstract （1634）      PDF（pc） （17687KB）（935）       Knowledge map    Save  A color display model of hyperspectral imagery is proposed, which optimizes high dimensional hyperspectral images nonlinearly into a three-dimensional color space. The property of spectral distance preserving in the model is considered as a main design criterion, and good separability is guaranteed in the final visualized color images so that the range difference between pixels and the range difference between the spectra are highly correlated. The method consists of four parts: 1) End-members are reduced to a two dimensional space as chromaticity coordinates. 2) Optimization of brightness values in the third dimension maximizes the relevance, thus color labels of each end-member are determined. 3) Linear mixing of colors are implemented in accordance with the various abundance value of each pixel. 4) A local optimization method is used to optimize and correct the color image to achieve color display of the image. Experiments show that the proposed model is feasible as the final color images have good visual quality with spectral distance well preserved and separable. It is suitable for HSI visual display. Related Articles | Metrics | Comments（0）

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GIS-Constrained Multi-scale Coastal SAR Image Segmentation ZHU Jun-jie1,2, DU Xiao-ping1,2, FAN Xiang-tao1,2, GUO Hua-dong1,2 Journal of Applied Sciences    2013, 31 (1): 79-83.   DOI: 10.3969/j.issn.0255-8297.2013.01.013 Abstract （2663）      PDF（pc） （10346KB）（9842）       Knowledge map    Save Both geographic information system (GIS) data and remote sensing imagery are spatial data with multi-scale features although they are concerned with different types of information. This paper discusses the multi-scale segmentation of high-resolution synthetic aperture radar (SAR) images near coastal zones constrained by GIS vector data. To obtain the first level segmentation results at the county-level scale, the high-resolution SAR image is segmented using the fractal network evolution method with the constraint of GIS data. Then, at the province-level scale, the first level results are aggregated to obtain the second level segmentation results. This segmentation results satisfy both the constraint of GIS vector data and the scattering characteristics of SAR images. False coastlines in the SAR images are eliminated. Experimental results show that the proposed method is effective, and the segmentation results can be used for further image statistics and analyses. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Shape Prior Extraction Based on 2DPCA Training CHEN Bo, CAI Jin-lin, CHEN Wen-sheng, LIU Zhen-he, LI Yan Journal of Applied Sciences    2013, 31 (1): 84-90.   DOI: 10.3969/j.issn.0255-8297.2013.01.014 Abstract （1656）      PDF（pc） （12644KB）（1231）       Knowledge map    Save  A shape prior extraction method based on two-dimensional principal component analysis (2DPCA)training is proposed for noisy image segmentation. Some ideal shapes are trained to obtain a group orthonormal projection vectors, and are then spanned to the 2DPCA space. The noisy image is projected onto this space, and least squares method is employed to find a dot nearest the projected dot in this space. The pre-image of this dot may not be one of the training shapes, but a linear combination of them. A pre-image strategy is then exploited to extract the shape prior. Experimental results show that the proposed segmentation method with shape prior is valid not only for noisy images, but also for images with occlusion and massing parts. Related Articles | Metrics | Comments（0）

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Robust Detection of Artificial Circular Target Center NIE Jian-hui, MA Zi, HU Ying Journal of Applied Sciences    2013, 31 (1): 91-96.   DOI: 10.3969/j.issn.0255-8297.2013.01.015 Abstract （1726）      PDF（pc） （9909KB）（1671）       Knowledge map    Save  Detection of artificial circular target center is a key in 3D measurements. In order to get accurate calibration and measurement in industrial fields, a robust algorithm for circular target center detection is proposed. Images with circular target are first preprocessed, and Canny edges extracted. The canny edges are then refined with an improved Snake algorithm, and sub-pixel edges are found using a Zernike operator. Accurate centers are obtained through robust ellipse fitting. Compared with traditional methods, the proposed algorithm can give accurate center detect results even if the target is damaged or soiled. Simulation results and real data show that the center detection error is less than 0.02 pixel in ideal cases, and less than 0.03 pixel when the target is damaged. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Blind Steganalysis Based on Image Content and Feature Fusion LI Kan1,2, PING Xi-jian1 Journal of Applied Sciences    2013, 31 (1): 97-103.   DOI: 10.3969/j.issn.0255-8297.2013.01.016 Abstract （1631）      PDF（pc） （7540KB）（1459）       Knowledge map    Save With increasing research on image feature vector extraction and classification, blind steganalysis is becoming more efficient and accurate. However, many existing methods use similar processing for all images without taking account the diverse image contents. This paper proposes a new approach based on image contents and feature fusion. The input images are divided into several classes according to the content complexity before feature extraction. Bhattacharyya distance is used to evaluate the usefulness of individual features and determine their weights. Steganalysis is subsequently conducted using a fusing approach and a support vector machine (SVM) classifier in a decision making process. Experimental results on several sets of  images demonstrate that the proposed steganalyzer outperforms some previous methods. It provides reliable results with reduced computational complexity. Related Articles | Metrics | Comments（0）

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Visual Tracking in Crowded Scenes with Multi-part Sparse Representation SHAO Jie 1, DONG Nan2 Journal of Applied Sciences    2013, 31 (1): 104-110.   DOI: 10.3969/j.issn.0255-8297.2013.01.017 Abstract （1871）      PDF（pc） （31666KB）（975）       Knowledge map    Save  This paper presents a target tracking framework applicable to complex crowded scenes with random movements. A robust tracking algorithm using a local sparse appearance model associated with a multi-part color representation is proposed. Sparsity is achieved by solving an l1 regularized least squares problem.Candidates with the smallest projection error is taken as the tracking result. All candidates are drawn based on a density distribution in a Bayesian state inference framework. The target templates are dynamically updated to adapt appearance variation at the end of a tracking iteration. We test the approach on numerous videos including different type of very crowded scenes with serious occlusion and illumination variation. The proposed approach demonstrates excellent performance in comparison with previous methods. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Cooperative Relay Transmission Scheme Based on Interference Cancelation LI Guo-you, ZHOU Ya-jian, YUAN Quan, YANG Yi-xian Journal of Applied Sciences    2013, 31 (2): 111-115.   DOI: 10.3969/j.issn.0255-8297.2013.02.001 Abstract （1771）      PDF（pc） （2611KB）（1327）       Knowledge map    Save In order to improve system achievable rate and throughput for wireless systems, this paper proposes a cooperative relay transmission scheme with interference cancelation. By overhearing interference signal as a priori information, the proposed scheme uses interference reconstruction and subtraction to cancel interference,reducing the time slot. Moreover, the paper derives the system achievable rate and outage probability expressions, and analyses the performance of different transmission schemes in diverse relay modes. Simulation results show that the proposed scheme can effectively improve the system achievable rate as the link signal-tonoise ratio (SNR) increases. By adjusting the transmission rate, optimal system throughput is obtained when the link SNR at the receiver is unknown. Reference | Related Articles | Metrics | Comments（0）

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Cooperative Spectrum Sensing Algorithm with Soft Fusion Based on Weighting LIU Xin, TAN Xue-zhi, ZHAO Ying Journal of Applied Sciences    2013, 31 (2): 116-122.   DOI: 10.3969/j.issn.0255-8297.2013.02.002 Abstract （1859）      PDF（pc） （1161KB）（1311）       Knowledge map    Save To improve the spectrum sensing performance, this paper proposes cooperative spectrum sensing that fuses the sensing information from every cognitive radio with soft fusion based on weighting. To reduce interference to the primary user and improve throughput of cognitive radio, two kinds of weight selection methods that minimize interference and maximize throughput are proposed. As large weighting is allocated to the cognitive radios with high SNR or low channel gain to the coordinator, proportion of the sensing information sent by the cognitive radio with high SNR to the fusion information at the coordinator is increased. Lost information due to channel fading is compensated. Simulation results show that performance of the algorithm is better than those based on SNR weighting and those without weighting. The proposed algorithm can also reduce influences of the fading channel on detection performance. The results show that, by selecting appropriate weights, interference can be reduced and throughput increased. Reference | Related Articles | Metrics | Comments（0）

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Multi-hop Relay Transmission Scheme Using Digital Fountain Code and Rotated Constellation LEI Wei-jia, LIU Hui-feng, XIE Xian-zhong Journal of Applied Sciences    2013, 31 (2): 123-129.   DOI: 10.3969/j.issn.0255-8297.2013.02.003 Abstract （2280）      PDF（pc） （3986KB）（1312）       Knowledge map    Save In multi-hop relay transmission, digital fountain codes can greatly improve transmission efficiency. A multi-hop relay transmission scheme based on fountain codes is proposed, which improves data relay performance in two ways: 1) Two relay nodes form a relay pair, and by using rotated constellation modulation, signal space diversity gain is obtained without sacrificing bandwidth efficiency. 2) An improved encoded packets linear combination algorithm is used to rebuild the encoded packets by the relay to realize packet diversity. Simulation results show that transmission efficiency of the multi-hop relay transmission is improved considerably, and transmission time reduced. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Transform Domain Anti-jamming Scheme for Spacecraft Payload in Satellite Communications BU Xiang-yuan, GUO Yu-kun, HAO Shi-guang Journal of Applied Sciences    2013, 31 (2): 130-134.   DOI: 10.3969/j.issn.0255-8297.2013.02.004 Abstract （2026）      PDF（pc） （958KB）（1333）       Knowledge map    Save With the development of modern satellite communication, integration of the functions of the satellite payload has significantly raised requirements of the hardware costs. This paper proposes an improved FFT algorithm that uses self-adapting truncation at each level of the FFT process to achieve a lager dynamic range of the signal’s spectrum as compared to the conventional FFT implementation. The improved algorithm has been applied in an inter-satellite link of a satellite navigation system with good anti-jamming performance, large dynamic range, and low complexity. Reference | Related Articles | Metrics | Comments（0）

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Minimum Distance-Based MIMO Precoding for Triple-Stream Transmission GU Qiang1, XU Xiao-dong1, JIANG Yi2, DAI Xu-chu1 Journal of Applied Sciences    2013, 31 (2): 135-141.   DOI: 10.3969/j.issn.0255-8297.2013.02.005 Abstract （2446）      PDF（pc） （2446KB）（1320）       Knowledge map    Save A new MIMO precoding method is proposed based on maximizing the minimum Euclidean distance between points in the received signal space for triple-stream transmission. Under a real-valued rotation matrix constraint, the proposed algorithm solves the non-convex optimization problem with two steps from the geometric viewpoint, named offline step and online step, respectively. In the offline step, all feasible surfaces are collected by expanding quadric surfaces within 3-dimensional space. In the online step, the precoder matrix is constructed with respect to the unique feasible surface chosen by particular channel implementation. Meanwhile, a closed-form expression of the minimum distance is also provided in this paper. Simulation results validate that the proposed method not only outperforms existing schemes with low computational complexity, but also has superior performance of more than 3 dB in terms of bit-error-rate (BER) with increase of the quadrature amplitude modulation (QAM) constellations. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Optimization of Time-Frequency Synchronization in OFDM System ZHAO Jun-hui1,2, Lü Chen1, TAN Guo-ping3 Journal of Applied Sciences    2013, 31 (2): 142-146.   DOI: 10.3969/j.issn.0255-8297.2013.02.006 Abstract （2102）      PDF（pc） （3883KB）（1114）       Knowledge map    Save This paper studies joint synchronization in OFDM systems under multipath fading, and analyzes the reason of timing error in the existing algorithms. An optimized joint synchronization algorithm using PN sequence is proposed. The algorithm achieves time synchronization by looking for the first falling edge of the sliding correlation sum value, chooses a size of the search window for the correlation sum value. Modified correlation calculation is introduced in the frequency synchronization. Simulation results show stability and superiority of the new algorithm under multipath environment, especially when the first path is not the strongest. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(8)

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Weighted Global Least Square Navigation Based on Measurable Image Sequence ZHANG Xiao-dong1,2, YANG Yuan-xi2, HU Qing-wu3, WANG Yuan-ming2 Journal of Applied Sciences    2013, 31 (2): 147-153.   DOI: 10.3969/j.issn.0255-8297.2013.02.007 Abstract （1708）      PDF（pc） （993KB）（1121）       Knowledge map    Save  A measurable sequential images positioning and attitude determination model which considered the coeffient matrix error of observing equation and its weight determination mothod is presented. The method can realize measurable image sequence aided DGPS/IMU navigation with reliable accuracy. Experiment results show that the proposed algorithm can overcome the effects of coefficient matrix errors with accuracy better than the traditional least square method. With the GPS outage in 2.5 km, the position accuracy is better than 13 m and the attitude error is better than 0.1m. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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Error Calibration of Three-Axis Magnetic Heading Sensor FENG Wen-guang, LIU Shi-bin, LI Ju-ping, GUO Bo, YANG Shang-lin Journal of Applied Sciences    2013, 31 (2): 154-158.   DOI: 10.3969/j.issn.0255-8297.2013.02.008 Abstract （2495）      PDF（pc） （5486KB）（1978）       Knowledge map    Save An improved least-square ellipsoid fitting method for calibrating of magnetic heading sensor is proposed to overcome instability of the traditional ellipsoid fitting algorithm due to singularity of the constraint matrix. The source of error and the mathematical model are discussed. A method of matrix block decomposition is used to solve the singularity problem of constraint matrix in the traditional algorithm. The ellipsoid parameter is calculated using the least-square algorithm. The proposed method overcomes instability of the traditional algorithm and reduces computation complexity. Simulation and experiments show that the proposed method is effective in magnetic heading sensor calibration. The precision of calibrated heading is better than 0.42m. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Khatri-Rao Subspace Wideband DOA Estimation for Nonlinear Array PAN Jie, ZHOU Jian-jiang Journal of Applied Sciences    2013, 31 (2): 159-164.   DOI: 10.3969/j.issn.0255-8297.2013.02.009 Abstract （2117）      PDF（pc） （3844KB）（1054）       Knowledge map    Save A Khatri-Rao subspace based wideband direction-of-arrive (DOA) estimation algorithm for nonlinear arrays without preliminary angle estimation is proposed. From steering vectors of the Khatri-Rao subspace virtual array, the wideband focusing matrix regardless of DOAs is constructed with a manifold separation technique.Benefited from the increased dimensions of the Khatri-Rao subspace virtual array, preliminary angle estimation can be avoided and the algorithm still performs well. On the other hand, by using Root-MUSIC, this method can avoid expensive spectrum searching used in conventional methods so as to reduce the computational burden. Simulations show that performance of the proposed method is close to the preliminary angle estimation needed Khatri-Rao subspace wideband DOA estimation algorithm, FKR-RSS. The proposed method performs better than FKR-RSS when the number of sources is more than the number of sensors. Reference | Related Articles | Metrics | Comments（0）

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Fast Maximum Likelihood Estimation of Class A Model JIANG Yu-zhong, YING Wen-wei, LIU Yue-liang Journal of Applied Sciences    2013, 31 (2): 165-169.   DOI: 10.3969/j.issn.0255-8297.2013.02.010 Abstract （2038）      PDF（pc） （949KB）（1577）       Knowledge map    Save This paper investigates the Class A noise model, and proposes a method to determine parameters of the model based on maximum likelihood estimation. The method uses FFT to reduce computation complexity and enhance performance by calculating two data groups from the original observed data. A method for estimating initial values is also proposed. Simulation results show that the method has good performance with a small number of iterations, and therefore is suitable for practical applications. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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No-reference Image Quality Assessment Based on Parameters of Wavelet Coefficients Distribution LI Hong-jun Journal of Applied Sciences    2013, 31 (2): 170-176.   DOI: 10.3969/j.issn.0255-8297.2013.02.011 Abstract （2130）      PDF（pc） （1625KB）（1579）       Knowledge map    Save We propose a no-reference method for image quality assessment to be used to various types of image distortions. We assess the image using statistic information of natural scenes, and use the generalized Gaussian density model to fit the marginal distribution of wavelet coefficients. Degree of image distortion is measured with the parameter values in the generalized Gaussian density model. Objective assessment of the image quality is obtained by quantifying the difference between the values of scale and shape parameters. Experimental results are consistent with subjective assessments, showing that the proposed method can be applied to most common types of image distortion to give good prediction. Reference | Related Articles | Metrics | Comments（0）

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Compressed Sensing Sparse Recognition for Target Classification from Multi-view Images LIU Ji-xin, SUN Quan-sen, CAO Guo Journal of Applied Sciences    2013, 31 (2): 177-182.   DOI: 10.3969/j.issn.0255-8297.2013.02.012 Abstract （2722）      PDF（pc） （3835KB）（1854）       Knowledge map    Save Multi-view image target classification is usually difficult. To deal with the problem, we propose a sparse recognition (SR) method with compressed sensing (CS) features. Sensing data of the original image are used as corresponding features. Both the test sample and the training sample set are integrated into an SR framework with their CS features. Classification results can be obtained by solving an l1-norm optimization problem. Experiments show that excellent performance of SR can be obtained by using CS features that retain information redundancy of the original sample. Meanwhile, multi-view image target classification is robust without preprocessing. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Soccer Detection in Images Based on Quaternion and Pulse Coupled Neural Network ZHENG Tian-yu, GU Xiao-dong Journal of Applied Sciences    2013, 31 (2): 183-189.   DOI: 10.3969/j.issn.0255-8297.2013.02.013 Abstract （3406）      PDF（pc） （7890KB）（923）       Knowledge map    Save  This paper proposes a soccer detection method that combines the attention selection model of phase spectrum of quaternion Fourier transform (PQFT) and pulse coupled neural network (PCNN). In the preprocessing, the region outside the field is removed, and the region of interest extracted using PQFT. The target is detected according to the physical characteristics such as color, shape and size. If no candidate or more than one are detected, a Kalman filter is used to make prediction. Simulation shows that the identification rate is improved by 9.6% and 14.9% respectively as compared to the dynamic Kalman filtering with velocity control and the real time ball detection framework introduced in the literature. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Multi-class Steganalyzer with Recompression Detection for JPEG Images LI Xing1,2, ZHANG Tao1, HE Zan-yuan2, LI Wen-xiang1, LI Kai-da1, PING Xi-jian1 Journal of Applied Sciences    2013, 31 (2): 190-196.   DOI: 10.3969/j.issn.0255-8297.2013.02.014 Abstract （1756）      PDF（pc） （3072KB）（1085）       Knowledge map    Save A novel multi-class steganalyzer with recompression detection for JPEG images is proposed to identify steganographic methods from singly and doubly compressed stego images. Based on the statistical distribution of the first digits of DCT coefficients, a JPEG recompression detection method is proposed. Features for blind detection are extracted from the histogram, intrablock correlation, interblock correlation and spatial blockiness. Finally, a multi-class detector against current steganographic methods is constructed with support vector machine. The experimental results show that the proposed recompression detection scheme outperforms the existing methods significantly, and is robust to embedding changes. The low dimensional steganalytic features have better performance, and the multi-class steganalyzer can identify the current JPEG steganographic methods reliably. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Text Categorization Based on Concept Knowledge DING Ze-ya1,2, ZHANG Quan1 Journal of Applied Sciences    2013, 31 (2): 197-203.   DOI: 10.3969/j.issn.0255-8297.2013.02.015 Abstract （2007）      PDF（pc） （1654KB）（1297）       Knowledge map    Save  To achieve semantic understanding, this paper proposes a method for text categorization based on concept-knowledge in the hierarchical network of concepts (HNC). The method includes two parts: feature selection using concepts and text categorization according to category relatedness degree. In this paper, category key concepts are explored by computing discrimination degree of concepts, and used to further reduce dimensionality of the feature space. Based on the category semantic information consisting of category key concepts and relatedness weights, the method of computing relatedness degrees between documents and categories is proposed. The category relatedness degree of document is used as a measure for text categorization. Experiments show that the proposed method can effectively reduce dimensionality of feature space, increase efficiency and ensure effectiveness of text categorization. Compared with SVM, KNN and Bayes, this method is the best in terms of F1 values at higher feature reduction levels. In terms of overall performance, the method is almost equivalent to SVM, and better than KNN and Bayes. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Prediction of IFTS Based on Deterministic Transition ZHENG Kou-quan1,2, LEI Ying-jie1, WANG Rui1, WANG Yi1 Journal of Applied Sciences    2013, 31 (2): 204-211.   DOI: 10.3969/j.issn.0255-8297.2013.02.016 Abstract （2285）      PDF（pc） （1205KB）（1059）       Knowledge map    Save To break the limitation in the description of the fuzzy trend of uncertain data sets and the partitioning intervals, the definition of intuitionistic fuzzy time series is regulated. A forecasting method of intuitionistic fuzzy time series is proposed, which optimize the domain-dividing interval with an intuitionistic fuzzy C-means clustering algorithm. Deterministic transition intuitionistic fuzzy rules are established by adding a back-tracking scheme. The proposed method can better reflect the characteristic distribution of the uncertain system and improve the prediction accuracy of time series in complicated environments. Validity and superiority of the method are checked with a classical instance. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(6)

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Duplicate Field Matching for Data Cleaning of Chinese Placenames YE Ou1, ZHANG Jing1,2, LI Jun-huai1 Journal of Applied Sciences    2013, 31 (2): 212-220.   DOI: 10.3969/j.issn.0255-8297.2013.02.017 Abstract （2084）      PDF（pc） （4347KB）（1943）       Knowledge map    Save To improve accuracy of field matching of Chinese placenames, an approximate duplicate detection and cleaning strategy and a matrix approximate duplicate matching method are proposed. In the strategy, a matrix approximate duplicate matching method is used. Frequencies of the same Chinese characters or word between two Chinese placenames can first be calculated with a matrix operation. Semantic similarity and structure similarity can be calculated using the frequencies. By combining semantic and structure similarities, they are considered as the basis of duplicate detection and data cleaning. Simulation experiments are conducted to prove feasibility and validity of the method, showing that the matrix approximate duplicate matching method is better than other existing methods in terms of precision and recall ratio. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Journal of Applied Sciences    2013, 31 (3): 220-.   Abstract （532）      PDF（pc） （29KB）（874）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Journal of Applied Sciences    2013, 31 (3): 220-.   Abstract （1131）      PDF（pc） （416KB）（750）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Adaptive Device-to-Device Cooperative Retransmission for Improving Multicast Efficiency in Cellular Systems ZHOU Bin1, HU Hong-lin2,3 Journal of Applied Sciences    2013, 31 (3): 221-227.   DOI: 10.3969/j.issn.0255-8297.2013.03.001 Abstract （1724）      PDF（pc） （2302KB）（1922）       Knowledge map    Save We focus on device-to-device (D2D) enhanced multicast transmission in cellular systems, formulate the relationship between the number of retransmitters and the efficiency of D2D retransmission, and derive a closed-form expression to search the optimal number of D2D retransmitters and the optimal sub-cluster partition. Based on the analysis, we propose an adaptive D2D cooperative retransmission scheme with limited channel feedback, which adaptively selects the number of retransmitters and the optimal routing. Exploiting the multicast gain and multi-channel diversity jointly, the proposed scheme achieves a significant gain in terms of spectrum efficiency compared to its counterparts with a fixed number of retransmitters. Reference | Related Articles | Metrics | Comments（0）

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Performance of Zero-Forcing Beam Forming System with Channel Prediction LU Min, ZENG Gui-gen, FENG Guang-zeng Journal of Applied Sciences    2013, 31 (3): 228-232.   DOI: 10.3969/j.issn.0255-8297.2013.03.002 Abstract （1933）      PDF（pc） （1558KB）（1647）       Knowledge map    Save  In this paper, capacity degradation of zero-forcing beam forming (ZFBF) system due to outdated CSI is investigated. A linear minimum mean square error (MMSE) channel predictor is employed to cope with the feedback delay and improve the capacity performance. Based on the power density function of the system’s signal to interference plus noise ratio (SINR), the analytic sum capacity expression relevant to the prediction error is derived. Numerical simulations show effectiveness of the predictor that exploits the channel’s temporal correlation against feedback delay. The simulation results are consistent with the analytic research. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Physical Layer Secrecy of Wideband System by Adding Random Noise Based on Channel’s Weak Characteristics PANG Hong-wei, JIN Liang, HUANG Kai-zhi, JI Jiang Journal of Applied Sciences    2013, 31 (3): 233-238.   DOI: 10.3969/j.issn.0255-8297.2013.03.003 Abstract （1708）      PDF（pc） （1490KB）（1169）       Knowledge map    Save To combat wiretapping of wireless wideband system, this paper presents a method for wireless wideband system physical layer secrecy in the time domain. The method adds random noise based on weak channel characteristic. First, the transmitter decomposes the nonsingular channel characteristic matrix into some sub-channels. The sub-channels with strong characteristic are selected to transmit useful information, and weak ones are transformed into a random channel. The signal received by legitimate receivers becomes steady, while the eavesdropper’s turns random. Simulation results show that the method can lower the requirements to the legitimate channel state while decrease SINR at eavesdroppers to keep its error probability high so as to enhance system security. Reference | Related Articles | Metrics | Comments（0）

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Three-Core LPFG Coupled Mode and Effective Refractive Index Calculation Method WANG Xue1, LIU Ke-qiang2 Journal of Applied Sciences    2013, 31 (3): 239-244.   DOI: 10.3969/j.issn.0255-8297.2013.03.004 Abstract （2197）      PDF（pc） （1614KB）（1113）       Knowledge map    Save Based on the coupled-mode theory, we study the coupling of three-core long period fiber gratings with two different structures and derive the mode coupling equations. The calculation method of cladding mode’s effective refractive index is also investigated. The rule of cladding mode’s effective refractive index change with the wavelength is discussed by numerical simulation. The results show that, the indices of both odd and even modes reduce as the wavelength increases. Different arrangements of three cores affect the extent of the index decrease. The results of this study provide theoretical guidance to the application of three-core fiber LPFG. Reference | Related Articles | Metrics | Comments（0）

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