Journal of Applied Sciences

FiniteAlphabet Based Blind Channel Estimation for OFDM Systems

JU Min;XU Zong

2008, 26(5): 441-447 .

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For OFDM systems, necessary and sufficient conditions for blind channel identifiability based on the finite alphabet property of information symbols are established. Under these conditions, a novel frequencydomain minimum distance (FMD) algorithm is proposed for blind channel estimation. By polyphase decomposition, the channel frequency response sequence is divided into several subsequences, and phase ambiguities of each subcarrier can be resolved by exhaustive searching only (L+1) elements in one subsequence, where L is the channel order. Simulation results show that the channel estimation accuracy of the FMD algorithm is better than the modified minimum distance (MMD) algorithm, both having the same computation complexity.

A Game Model of Nodes’Strategies with Incomplete Information in P2P Network

WANG Hao-yun;ZHANG Shun-yi;ZHAO Zhen-dong;MA Yan-ling

2008, 26(5): 448-454 .

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第26卷〓〖HT〗〖ST〗

〖CM)〗〖SM)〗〖FQ(5*2。46，ZX，BP-W〗〖HT1.〗〖HT〗〖CD10〗〖HJ*3〗

〖HT6SS〗〖HTH〗收稿日期：〖HTSS〗；〓〖HTH〗修订日期：〖

HTSS〗〖HTH〗基金项目：〖HTSS〗[ZK(][ZK)]〖HTH〗作者简介：〖HTSS〗〖

ZK(〗王浩云，博士生，研究方向：网络QoS管理、网络协议分析、系统智能，E

mail:why-583@163.com；张顺颐，教授，博导，研究方向：计算机通信网及IP

技术，Email:dirzsy@njupt.edu.cn〖ZK)〗〖HT〗〖HJ〗〖FQ)〗〓〓〖HT5”H

〗文章编号：〖HTSS〗 02558297(2008)05044807〖HJ9mm〗〖HJ〗〖JZ(

〗〖HT2H〗〖WTHZ〗〖STHZ〗基于不完全信息博弈的P2P网络节点行为策略模型

〖ST〗〖WT〗〖HT〗〖HJ6mm〗〖HJ〗〖HT4，5F〗王浩云1，〓张顺颐1，〓赵振东1，〓马燕玲2〖HT5”SS〗（）〖HT〗〖JZ)〗〖HJ8mm〗〖HJ〗〖GK2!2〗〖HT5”H〗摘

〓要：〖HT5”SS〗〖HT5”H〗

关键词：〖HT5”SS〗〖HT5”H

〗中图分类号：〖HT5”SS〗TP393〓〓〓〖HT5”H〗文献标志码：〖HT5”SS

〗〖WTBZ〗A〖HT〗〖HJ8mm〗〖HJ〗〖HK〗〖WT4”HZ〗〖STBZ〗〖JZ(〗A

Game Model of Nodes’Strategies with Incomplete Information in P2P

Network〖HJ6mm〗〖HJ〗〖WT〗〖ST〗〖WT5BZ〗WANG Haoyun1,〓ZHANG

Shunyi1,〓ZHAO Zhendong1,〓MA Yanling2〖WT5”BX〗(1.

Jiangsu Province Engineering Research Center of Telecommunication and

Network Technology, Nanjing University of Posts and

Telecommunications, Nanjing 210003, China; 2. Faculty of Information

Engineering and Automation, Kunming University of Science and

Technology, Kunming 650051, China)〖WT〗〖JZ)〗〖HJ7mm〗〖HJ〗〖WT〗

〖HJ*3/8〗〖WTHZ〗Abstract：〖WT〗This paper presents a game model of

node strategies with incomplete information in P2P networks. The model

classifies node strategies to several sets according to the node types.

Based on it, the paper analyzes the transfer conditions of different

strategies in the game model with incomplete information, as well as

the betrayal of the node types. Simulation of the evolution of the game

is carried out, showing effectiveness of the proposed model.

Bit-Loading Algorithm for HomePlug AV Standard in Power Line Communications

ZHANG Sheng-qing;WU Bin;YU Dong-hai;ZOU Cai-rong

2008, 26(5): 455-460 .

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In this paper, an efficient bit-loading algorithm is proposed for HPAV specification, aiming at maximization of data rate under the constraint of transmission power spectrum density and bit error rate. The algorithm is based on preallocation and adopts a new iterative method to reduce computational complexity. Simulation results show that the proposed algorithm can achieve optimal allocations while computational complexity is about half of existing methods.

Simplified CMOE Recursive Adaptive Multiuser Detection for MIMO MC-CDMA

ZHAO Fa-yong;FENG Guang-zeng

2008, 26(5): 461-466 .

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This paper proposes a recursive adaptive algorithm of joint channel estimation and multi-user detection based on a simplified constraint minimum output energy (CMOE) criterion for space-time block codes (STBC) MIMO MC-CDMA. It solves the adaptive value of the variable diagonal loading. Optimal step-size semi-blind adaptive channel estimation is proposed for increasing convergence rate and accuracy. The channel estimation error and BER performances of different algorithm under different environments are compared.

Space-Frequency Transformation with Two-Stage Detector in MIMO OFDM Systems

ZHOU Ji-ting;YANG Xiu-mei;XIONG Yong;

2008, 26(5): 467-472 .

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In this paper, a novel space-frequency transform scheme with good performance to suppress the co-antenna interference (CAI) in wireless communication is presented. The scheme is implemented in a MIMO OFDM Turbo transceiver. At the transmitter, we use a pre-designed symbol-mapping pattern for each transmitting antenna. At the receiver, according to the pre-designed transmitter structure, a two-stage detector receiver, including MMSE detection and interference subtracted step in stage one and BCJR (Bahl Cocke Jelinek Raviv) or SOMA (soft output M-algorithm) (M-algorithm) in stage two, performs two successive decisions through an iterative process. In each iteration process, soft information is exchanged between the detector and the decoder, and interference among multiple streams is subtracted. Simulation results show that the proposed scheme with BCJR achieves better performance over D-STTD CC coding. It also outperforms D-STTD Turbo coding after two and three iterations in 4×4 MIMO systems.

Adaptive Resource Allocation with Proportional Fairness for MIMO-OFDMA Downlink

DU Na;XU Da-zhuan

2008, 26(5): 473-478 .

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This paper presents an adaptive resource allocation scheme based on proportional fairness for MIMO-OFDMA downlink systems. Based on MIMO channel state information and by using the eigen channels to determine subcarrier and power allocation, the proposed scheme has the ability to simultaneously exploit space, frequency and multiuser diversity to improve spectrum efficiency. A non-iterative linear power allocation method with low complexity is derived with the proposed relaxation of strict user rate proportionality constraints. Simulation results show that the new adaptive allocation scheme can achieve good tradeoff between capacity and fairness, and provide much better capacity gain than conventional schemes, while requiring significantly less computation complexity.

Optimum Design of Unitary Signal Constellation for Differential Space-Time Modulation

HUANG Bing-gang;WU Xin-rong;ZHOU Zhi-jie;ZHAO Lu-wen

2008, 26(5): 479-484 .

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To get design parameters of unitary signal constellation for differential space-time modulation, a novel algorithm using genetic search is presented, which combines diagonal parameters and rotation factors of rotated unitary signal constellation into a codeword. The error performance of unitary signal constellation with rotated matrix is better than diagonal matrix, and the error performance of the codeword with the proposed design parameters is better than that described in the literature. The proposed algorithm can obtain design parameters very close to the optimal design.

Performance Analysis of SC/MRC Scheme over Correlated Nakagami Fading Channel

LI Tao;WANG Bao-yun;TIAN Feng

2008, 26(5): 485-488 .

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In a MIMO system, the transmitter antenna selection technique, which selects one antenna for transmitting, can reduce the number of required RF chains and alleviate system complexity and costs. In this paper, we analyze performance of the system that uses maximal ratio combining(MRC) at the receiver and operates over correlated Nakagami fading channels. The probability distribution density function of the output SNR is derived, and an accurate expression of bit error rate (BER) is obtained, which only includes ordinary function.

A Resource Allocation Algorithm Based on Cooperative Game Theoretic Framework

HUI Yi;ZHOU Zhi-jie;ZHANG Wen-qiang;HUANG Bing-gang;ZHAO Lu-wen

2008, 26(5): 489-494 .

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A adaptive resource allocation algorithm of multiuser MIMO OFDM systems based on cooperative game theoretic framework is proposed and simulated. The algorithm allocates resources based on the Pareto solutions of Nash Bargaining Solution and Raiffa-Kalai-Smorodinsky Bargaining Solution, make the rate of users close to the Pareto solution. Simulation results show that the performance of the proposed algorithm is obviously better than the fixed allocation algorithm, and close to the max rate scheme. But the impartiality of the proposed algorithm is the best.

A Scheme of OFDMA Radio Resource Allocation to Different Services

LU Guang-yue;CHEN Wen-yi;WANG Jun-xuan

2008, 26(5): 495-498 .

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Allocation of OFDMA radio resources to multiple services with different QoS requirements is considered in this paper. First, time sensitive services receive high priority to get necessary resources to meet their time delay requirements, and obtain subcarrier clusters to lower the feedbacks and a little more power on each subcarrier cluster to reduce occupancy of the bandwidth. Secondly, the remaining resources after the first step are adaptively assigned to date services to realize the subcarrier-power-integer bits allocation to maximize throughput of OFDMA systems, with the help of remaining power reallocation. Simulations indicate that, using the proposed scheme, spectrum efficiency can be improved by 50% and drop-rate for the time-insensitive users is almost zero with large SNR.

Improving Line-Based Light Balancing for Text Images

Chin-chen CHANG;Chin-hao CHEN;Pei-yu LIN

2008, 26(5): 499-505 .

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With digital cameras, an inappropriate light source often leads to uneven illumination of the picture. The same problem also occurs when capturing an image via digital scanners; irregular illumination seriously distorts the image quality. Light balancing can eliminate such uneven illumination in multimedia. In this paper, we provide an improved version of this technique for text images. The new version adopts a contrast weight to amplify distinction between the text and the background. This can equalize the histogram and reduce uneven contrast of the disproportionate light distribution. The simulator shows that the new version can effectively improve the distorted documents with satisfactory quality and readability.

Observability Analysis of Satellite Autonomous Navigation System Using Single Pulsar

ZHENG Guang-lou;LIU Jian-ye;QIAO Li;XIONG Zhi

2008, 26(5): 507-510 .

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Observability of the single pulsar-based satellite autonomous navigation system is studied. The state equation and measurement equation of the system are presented. According to the characteristics of linearization of the extended Kalman filter, the observability analysis of piece-wise constant system (PWCS) is carried out to study the system observability. In the theoretical analysis, the observable matrix of this system is nearly singular, and the system is completely unobservable. It is demonstrated by simulation that, with measurements from only one pulsar, the estimated position and velocity propagated by satellite dynamics can be improved.Errors in position and velocity can be kept within certain limits in short time; but the satellite orbit cannot be estimated accurately over long time.

Tone Recognition of Whispered Mandarin Using Ant Colony Clustering Neural Network

CHEN Xue-qin;ZHAO He-ming;YU Yi-biao

2008, 26(5): 511-515 .

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Based on analysis of acoustic and perception characteristics of whispered mandarin speech, a tone detection method using ant colony clustering is proposed. A multi-dimension feature vector consisted of amplitude envelope, formant, vocal tract length, average firing rate of auditory nerves is chosen as the mainly cue for whispered tone. The feature vectors are clustered by ant colony algorithm and then input to regional supervised feature mapping neural network for training and recognizing. The experiment results show that 87.5% average recognition accuracy could be reached and the performance of proposed method is improved significantly compared with classical models.

Adaptive Filter Using Orthonormal Basis Functions

LIU Qiang;WANG Xin-wei;CHEN Ren-wen;LIU Lin

2008, 26(5): 516-520 .

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To enhance performance of traditional filters, an improved filter is proposed using orthonormal basis functions. The mathematical orthonormal function is introduced into the structure of filter. Prior information of the system is obtained by mapping the system model to orthonormal basis function. This is different from the present filters. Comparison between traditional filters and the orthogonal filter is made. Computation formulations of the new algorithm are given. Results of numerical simulation and the practical application to aircraft cabin noise rejection indicate that the new filter algorithm has fast convergence and high stability with small number of tap-weight.

Image Texture Segmentation Based on Krawtchouk Moment and SVM

WU Ke;SHU Hua-zhong

2008, 26(5): 521-525 .

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A new image texture segmentation method is presented based on the Krawtchouk moments and support vector machine (SVM). The Krawtchouk moments in small local windows of each pixel in the image are computed and a nonlinear transducer is used to map the moments to texture features. The feature vector is then input to SVM for classification. Compared with the segmentation results based on the Zernike moment, the proposed method can produce better results.

Land Clutter Simulation of Space-Based Surveillance Radar for Natural Scene

WANG Hai-tao;ZHU Gen-cai;BEN De;PAN Ming-hai;YU Wen-zhen

2008, 26(5): 526-530 .

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To evaluate performance of the space-time adaptive process (STAP) algorithms for space based radar (SBR), a method for simulating clutter scenes with high fidelity is described. Instantaneous reflectivity scene of specific site is simulated first based on the corresponding land cover data, terrain data and radar operation parameters. Ideal and estimated values of clutter covariance matrix are then calculated using the instantaneous reflectivity scene, according to array pattern, effects of range foldover and earth rotation. The effect of internal clutter motion (ICM) is considered using the Billingsley spectrum model. The results show that statistical difference between simulated reflectivity scene and the reality is less than 5 dB, and simulated clutter environment of SBR can be used to analyze the performance of STAP quantitatively.

Implementation of Globus Resource Management Model Based on Service Level Agreement

QI Chao;ZHANG Jing;HE Ju-hou

2008, 26(5): 531-535 .

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As the Globus resource management (GRM) model lacks QoS mechanism, this paper proposes an extended framework for GRM, GRMF, which can support dynamic QoS renegotiation. WS-Agreement specification is extended to support renegotiation and modification of the agreement terms during the service provision. Then, integration of the extended WS-Agreement framework with GRM model is studied. The dynamic QoS renegotiation-supported GRMF is devised accordingly. Feasibility of the framework is validated by realizing key web services. The theoretical analysis and experimental results show that the framework can improve the success ratio of tasks, and allow better resource load balancing within the grid.

Run-List Based Connected Components Labeling for Blob Analysis

ZHANG Er-hu;FENG Jiang

2008, 26(5): 536-540 .

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Blob analysis is an important part of machine vision system. Fast and efficient Blob analysis is needed to meet real-time demands in industrial applications. This paper presents a fast Blob analysis algorithm based on run-list. The algorithm uses the method of run-lists and dynamic array to build dynamic chain tables for storing two neighbor rows run-coding information. The run list node can be labeled by analyzing its connectivity. This algorithm requires only a single pass over the image, without the need to build an equivalence table and to unite equivalent labels. It can avoid label redundancies present in conventional algorithms. In addition, it can also label holes in blobs. Experimental results show that it can correctly label any Blob regions with complicated shapes and random numbers, and compute blobs features. With faster speed and good stability, the proposed labeling algorithm has been successfully applied in an on-line defect detection system for printed matter.

Performance Optimization of ISG Hybrid Electric Vehicles with Optimal Operating Points

YE Xian-jun;ZHAO Han;ZHANG Bing-li

2008, 26(5): 541-546 .

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In order for ISG hybrid electric vehicles to reduce fuel consumption and emissions, a controller model for timely distributing driving torque to the internal combustion engine and ISG motor based on the adaptive neural-fuzzy inference system (ANFIS) algorithm is established. The performance model of the vehicle is based on the characteristics of internal combustion engine and ISG motor. Data of optimal operating points for training ANFIS system is obtained by finding the extremum of a multivariable function. An ANFIS system is designed and developed to control the torque distribution for ISG hybrid vehicles. Simulation results show improved performance and validity of the energy management strategy based on ANFIS.

Influence of Attenuation Coefficient on Phase Detection Based SPR Sensors

ZHANG Ying-ying;YIN Cheng;LAI Jian-cheng;LI Zhen-hua

2008, 26(5): 547-550 .

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Taking sample’s absorption property into consideration and introducing an imaginary part of its refractive index, we have analyzed the dependence of the phase difference of surface plasma resonance (SPR) on the sample attenuation coefficient. It was validated experimentally. Under the optimized operating condition for transparent samples, the changing rate of the phase difference curve near the resonance angle was reduced with the enhancement of the sample’s attenuation coefficient. This degrades sensitivity of phase detection of the SPR based sensors. Nonetheless, it can be effectively compensated for by simply adjusting the thickness of Au film.

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