Table of Content

26 February 2010, Volume 44 Issue 02 Previous Issue    Next Issue

Radiao Electronics, Telecommunication Technology

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Irregular Low Density Parity Check Decoder Design and Its Optimized Decoding Process CHEN Xuwei，GAN Xiaoying，YU Hui，HUA Ying，XU Youyun 2010, 44 (02):  149-0155.  Abstract ( 4198 )   Save This paper proposed an improved decoder structure which can be applied to any irregular quasicyclic low density parity check (LDPC) codes. The decoder needs only one shuffle network by adjusting the memory cells of the RAM. The pipeline conflicts due to the irregular LDPC codes can be solved by properly inserting idle clocks and preprocess of the low density parity check matrix. Meanwhile, such decoding process still achieves high throughput and suffers little decoder performance loss. Related Articles | Metrics

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A Method of Mobility Fast Handover Based on Locator/ID Separation Protocol XU Dongxiao,JIANG Lingge,HE Chen 2010, 44 (02):  156-0160.  Abstract ( 4478 )   Save Locator/ID separation protocol (LISP) implements endpoint mobility by deploying mobile IP (MIP) on its basic framework. Considering the disadvantages of long handover latency, high rate of packet loss and complexity in deploying, an FMLISP was introduced to achieve mobility fast handover. Similar to FMIPv6, FMLISP uses link layer mechanism to trigger handover. Considering the LISP infrastructure, the new method omits some unnecessary procedures in FMIPv6 such as new CoA allocation, duplicate address detection, and establishment of bidirectional tunnels. The simulation result shows that FMLISP has notable improvement in handover latency compared with LISP+MIP approach. Moreover, the data cache mechanism can effectively reduce the packet loss. Related Articles | Metrics

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A New User Selection Algorithm for MIMO System with Block Diagonalization LV Jing1,LUO Hanwen1,ZHANG Jing2 2010, 44 (02):  161-0164.  Abstract ( 4368 )   Save A new lowcomplexity user selection algorithm was proposed for multipleinput multipleoutput (MIMO) system employing block diagonalization (BD) with othercell interference (OCI) suppression. The algorithm iteratively selects users through greedy search. In each user selection step, the user who contributes most to the cell capacity is added to the selected user set, and the number of activated users is adaptively adjusted to maximize the cell capacity. The simulation results show that the proposed algorithm can achieve about 99% of the cell capacity of the complete search at high SNRs, and at low SNRs the two come out almost the same. Related Articles | Metrics

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x264 Fast Mode Selection Based on Hierarchical Decision LIU Shuo,SONG Li，YU Songyu 2010, 44 (02):  165-0170.  Abstract ( 4054 )   Save This paper carries out research on the highly optimized mode decision algorithm of x264 software and accurately pins out its redundant points. The mode selection process is reorganized hierarchically. Auxiliary inter modes’ invalidating condition and main inter modes’ validating condition are proposed.New mode selection algorithm based on them is designed. According to the experimental results, the new algorithm brings remarkable speed gain for both P and B slices. Related Articles | Metrics

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Residual Ratio Iteration Termination Condition for MP Method LIANG Wei1,QUE Peiwen2,CHEN Liang1,LEI Huaming2 2010, 44 (02):  171-0175.  Abstract ( 4707 )   Save The residual ratio iteration termination condition for matching pursuit (MP) method was developed. It can erase the disadvantage of the traditional termination condition which can not terminated in terms of an ultrasonic signal with extremely low SNR. The error criterion is used to monitor the acceptability of the unitnorm vector obtained by the matching pursuit performance. Moreover, the matching pursuit operation will continue until the error ratio is less than a predetermine threshold. The error criterion is an important factor for the signal approximation while noise level is unknown. The numerical simulations and experimental results prove the good performance of the proposed approach which is robustness to be as an iteration termination condition for MP method. Related Articles | Metrics

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ThreeDimensional Simulation Method of Mold Filling during Microchip Plastic Encapsulation WANG Hui,ZHOU Huamin,LI Dequn 2010, 44 (02):  176-0179.  Abstract ( 4437 )   Save In order to study the filling process of the plastic encapsulation, a stabilized three dimensional simulation method was presented. In this method, NS equations combined with Kamal conversion equation were introduced as governing equations, and FAN(Flow Analysis Network) technique was used to track melt fronts for each time step. To avoid numerical surge during calculation and achieve stabilized scheme, GLS(Galerkin Least Square) scheme was used in the momentum equation, GLS\\GGLS(Gradient Galerkin Least Square) scheme was used in the energy equation, and SUPG(Streamline Upwind Petrov Galerkin) scheme was used in the conversion equation. The experiment proves this method has a good stabilization and accuracy. Related Articles | Metrics

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Thermal Design and Simulation of MOSFET in HighFrequency Power Supply Based on Thermal Resistance Network HU Haila,WANG Shigang，MO Jinqiu,FAN Jinqiu 2010, 44 (02):  180-0184.  Abstract ( 4617 )   Save This paper described the thermal design of metaloxidesemiconductor fieldeffect transistor(MOSFET) which is typically applied in highfrequency power supply. After introducing the thermal parameters of MOSFET, the thermal risistance networks for single and couple pieces were established respectively, and further temperature formulations at each interface were deduced. Based on the above work, a suitable heat sink was figured out to solve the thermal problem in a highfrequence power supply which contains four MOSFETs compactively fix in a PCB. Finally, the performance of heat sink was verified with the help of computational fluid dynamics（CFD）software ICEPAK, and the thermal risistance networks are proved to be practical in engineering application Related Articles | Metrics

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Downlink SINR Distribution of Orthogonal BeamForming Space Division Multiple Access System CHEN Lei1,LUO Hanwen1,LIU Renmao2 2010, 44 (02):  185-0188.  Abstract ( 4218 )   Save This paper analyzed the performance of vector quantization with codebook comprised of multiple sets of orthogonal vectors in space division multiple access(SDMA) systems with limited feedback. Using probability theory, mathematical expressions for the channel direction information (CDI) vector quantization error distribution were derived considering the orthogonality of codewords. Then the downlink SINR distribution of orthogonal beamforming SDMA systems was obtained. The numerical results show that the analytical deduction is coincident with the actual facts. Related Articles | Metrics

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A Hybrid Particle Filter for Symbol and Carrier Frequency Synchronization in MIMO Systems ZHANG Jing,LUO Hanwen，JIN Ronghong( 2010, 44 (02):  189-0192.  Abstract ( 4489 )   Save A hybrid particle filter was proposed for the synchronization of symbol and carrier frequency in multipleinput multipleoutput wireless communication systems. It is based on maximization of a posterior probability. In the receiver side, propagation delay and carrier frequency offset are represented by a set of random particles. The important weights of particles are calculated by combining the channel parameters, which are estimated by the Kalman filter. Moreover, sequential importance sample and resample are implemented to update the weights and maintain the variety of particles. The approach does not directly sample on multidimensional channel space to overcome the disadvantage of computation efficiency reduction. Numerical results are presented under a fourtransmit tworeceive wireless communication system. They demonstrate that the estimation accuracy of the approach is high as well as the iterative step is short. The bit error rate performance is comparative to the situation with ideal parameters. Related Articles | Metrics

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Downlink Performance and Capacity of Improved Distributed Antennas System SU Caiguo,HE Chen 2010, 44 (02):  191-0197.  Abstract ( 3822 )   Save An improved cellular distributed antennas system (IDAS) configuration was proposed, which adopts directional antennas and lies them reasonably. Comparing with the existing cellular distributed antennas system (EDAS) configuration and traditional cellular (TC) configuration, both the theoretic analysis and simulations validate that IDAS can acquire lower symbol error probability and larger channel capacity especially in the adverse channel conditions. The influence of shadow fading to the signal transmission was also discussed. Related Articles | Metrics

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An Inband Proactive Sensing Strategy Based on Queuing Model in Cognitive Radio Networks HUANG Jixiang,JIANG Lingge,HE Chen 2010, 44 (02):  198-0203.  Abstract ( 4074 )   Save This paper formulated a priority queuing model for the periodical inband sensing mechanism. On the basis of the analysis of this model, in which the idle time of the secondary user is lack of utilization, the paper proposed an idle time based inband proactive sensing strategy (ITIPSS). In addition to executing periodical inband sensing, ITIPSS uses the idle time gaps of the secondary user to detect the primary’s return proactively. The simulation results show that ITIPSS can shorten the detection delay to the primary user significantly and improve the protection of the primary user efficiently. Related Articles | Metrics

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A Method of Pseudonoise Code Acquisition in Both NonGaussian and Multiplicative Noise ChannelsS HEN Feng,SUN Feng 2010, 44 (02):  204-0208.  Abstract ( 3810 )   Save In order to solve the pseudonoise (PN) code acquisition in nonGaussian multiplicative noise channels, a new detector was proposed. Modeling the acquisition problem as a hypothesis testing problem, the detector is derived for multiplicative noise, based on the locally optimum detection technique. The numerical results show that the proposed detector can offer substantial performance improvement over the conventional schemes in multiplicative noise channels. Related Articles | Metrics

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A Spectrum Sensing Method Based on High Order Cyclic Statistic LIN Yingpei,HE Chen,JIANG Lingge,HE Di 2010, 44 (02):  209-0213.  Abstract ( 4037 )   Save A spectrum sensing method based on the high order cyclic statistic(HOCS) in cognitive radio was presented according to the strict cyclostationarity of the HOCS. The binary hypothesis test model and the test statistic are constructed and the explicit formula of the detection probability is derived by exploiting the asymptotic optimal estimation theory. The computational complexity of the proposed method has nearly the same order as that of energy detection(ED) by comparing their real multiplication operation times. The simulation results show that the new scheme has superior performances of detection and resistance to same frequency interference compared with the conventional spectrum sensing methods. Related Articles | Metrics

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A Novel Multilayered Crosscoupled Substrate Integrated Waveguide Filter in Lowtemperature Cofired Ceramic WEI Qifu,LI Zhengfan，LI Lin 2010, 44 (02):  214-0217.  Abstract ( 4052 )   Save A fourthorder multilayered crosscoupled filter realized by substrate integrated waveguide structure was proposed. A new topology was adopted to construct the filter. Due to the presence of the crosscoupling between nonadjacent resonators, two finite frequency transmission zeros near the passband are produced to improve the performance of the filter. The filter was designed and simulated by high frequency structure simulator (HFSS), and fabricated using eightlayer lowtemperature cofired ceramic (LTCC) technology. The measured results show a good agreement with the simulated results and validate the structures of the proposed filter. Related Articles | Metrics

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Design of Frequency Resolution Enhanced Digitally Controlled Oscillator DAI Xuan,JIN Jing,ZHANG Weicheng,ZHOU Jianjun 2010, 44 (02):  218-0222.  Abstract ( 3827 )   Save A novel way to improve the frequency resolution of digitallycontrolled oscillator(DCO) for quadband global system for mobile communication(GSM) was proposed. The characters and principle of DCO are described at first. Then the proposed novel series switched varactor model is analyzed. The fine tuning capacitor bank in DCO is then implemented using this varactor to achieve better frequency resolution. A DCO in 90 nm complementary metal oxide semiconductor(CMOS) process using this new structure achieves a frequency resolution of 1.6 kHz without dithering and a phase noise of -152 dBc/Hz at 20 MHz offset when oscillating at 3.1 GHz. The total power consumption is 8.16 mW. The simulation shows this DCO satisfies quadband GSM requirement and is capable of alldigital phaselocked loop(ADPLL) application. Related Articles | Metrics

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A Core Union Test Scheme for Reducing System on Chip Test Time YI Maoxianga,LIANG Huaguoa,WANG Weib,ZHANG Leib 2010, 44 (02):  223-0228.  Abstract ( 4071 )   Save An extended pattern runlength (xPRL) coding approach was introduced, which uses a dynamic don’t care bit propagation strategy to improve test data compression. Multiple core test sets for testing system on chip (SoC) are merged into a single data stream and compressed by the xPRL coding. A reconfigurable serial scan chain was designed to make the test vectors of different cores unionapplicable. The proposed scheme was applied to an example of SoC with six large ISCAS’89 benchmarks embedded. The analysis and experimental results show that compared to the previous techniques, in which a test set is compressed and applied independently of others, our technique can increase compression rate and, at the same time, reduce redundant shift and capture cycles during scan testing, which thereby can effectively reduce test application time of SoCs. Related Articles | Metrics

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Speech Dereverberation of Single Channel SHEN Xizhong1，2,MENG Guang2 2010, 44 (02):  229-0233.  Abstract ( 4428 )   Save A new method of blind dereverberation of single channel was proposed to solve the existing problem in speech signal processing. Firstly, segmentation of speech signal with variant length is carried on the sampled speech signal, and the complex cepstrum is applied to the valid segments. Then, the preestimation of the room impulse response is obtained by this method, and so is the inversefilter solution. At last, blind deconvolution is used by taking the inversefilter as the initial parameter of the algorithm. The simulations and experiments show its validity of the proposed method. Related Articles | Metrics

Automation Technique, Computer Technology

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Virtual Reality Grid Environment for Collaborative Assembly Simulation HU Yong,WU Dianliang,FAN Xiumin 2010, 44 (02):  238-0242.  Abstract ( 4513 )   Save Because of numerous component models and massive dataset in assembly design for complex product, common virtual assembly software can not process them in realtime mode. A new virtual reality grid environment was proposed, which uses grid resource management and shared technology to aggregate large numbers of idle resources in enterprise; uses parallel rendering framework based on Sortlast algorithm and remote video visualization to support realtime interactive assembling simulation. After taking a collaborative simulation for automotive assembling workstation, the main functions and design objectives of the system were affirmed. The result shows that the system can better solve the problem of realtime process for large complex scene in the present conditions of hardware, and observably improve the usage efficiency of enterprise resources. Related Articles | Metrics

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Study on the Handling Method of RFID Complex Event for Logistics Tracking and Tracing LI Minbo,CHEN Chen，LI Hua 2010, 44 (02):  243-0247.  Abstract ( 4211 )   Save Traditional RFID middleware does not research the business definition of RFID event and related integration. Considering the RFID application requirement of logistics tracking and traceability, RFID semantic event and XML element were used to describe the information of product logistics. According to the business type of logistics, the classification and element definition of the RFID events were analyzed. Through buffered priority queue rule, RFID complex event was processed simultaneously and scheduled in real time. An integration framework of RFID events with ERP (Enterprise Resource Planning) system was put forward. Different business documents of ERP can be parsed by XML file and converted to uniform objects. RFID complex event was used to control business workflow and provide some alarm. Finally, RFIDbased traceability of product was realized through two methods of web service and short messaging service. Related Articles | Metrics

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High Degree of Accuracy Medical Image Fusion Algorithm Based on GPU Hardware Acceleration XU Xian，YANG Jie 2010, 44 (02):  248-0251.  Abstract ( 4475 )   Save This paper proposed a frequency domain nonsubsampled contourlet transform (FNSCT) algorithm accelerated by graphic processing unit (GPU). This approach builds a simple and highspeed nonsubsampled contourlet transform in frequency domain to eliminate the ringing and pseudoGibbs phenomena caused by wavelet or contourlet transformation. Also it accelerates the time domain nonsubsampled contourlet transform (NSCT) algorithm with the help of GPU to achieve a high speed and accuracy medical image fusion method. Related Articles | Metrics

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Modeling of Clinical Pathway Based on Hierarchical Timed Colored Petri Net ZHAO Yanli,JIANG Zhibin,LI Na 2010, 44 (02):  252-0258.  Abstract ( 4321 )   Save In order to establish optimal clinical solution and speed up clinical pathway system construction, a modeling method using hierarchical timed colored Petri net (HTCPN) was put forward, thus clinical status, information flow as well as the relationship between clinical activities can be visually controlled. With the designed SML functions, realtime input is available for diagnostic decision and checking information. Parameters and conditions are set up to forecast and analyze variations in diagnostic processes, also automotive adjustment is able to be implemented. Using defined time stab of tasks, simulation analysis is conducted for different distributions of patients’ arrival rate, and then methods for resources allocation are proposed to improve the effectiveness of clinical pathway implementation. The test results confirm that this method is effective in solving current clinical problem, and it paves the way for developing clinical pathway workflow system. Related Articles | Metrics

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Dynamic Computation of Gap among Objects for Interactive Virtual Assembly ZHEN Xijin,WU Dianliang,ZHU Hongmin,FAN Xiumin 2010, 44 (02):  259-0263.  Abstract ( 4404 )   Save A method of realtime computing the gap among objects for interactive virtual assembly was proposed. In this method, a single or a group of bound box is confirmed firstly based on getting the minimum distance among the hierarchical bounding volume（BV）, as result the nearest goal polygon group is gotten. Then the minimum distance and location of the gap are calculated. This method has the advantage of being able to use the hierarchy collision detection model existing in the virtual assembly environment, as well as parallel computing system. The method is integrated in DPVAE (distributed parallel virtual assembly environment) system and verified with application of dynamic gap computation of car rear suspension assembly. The result shows that the method can be used for space analysis in realtime interactive virtual assembly operations environment. Related Articles | Metrics

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ImmunityBased Security Model for Wireless Mesh Networks YI Ping1,2,WU Yue1，ZOU Futai1,LIU Ning1,CHEN Jialin1 2010, 44 (02):  264-0270.  Abstract ( 4183 )   Save A wireless Mesh networks is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. The flexibility in space and time induces new challenges towards the security infrastructure. Contrary to their wired counterpart, wireless Mesh networks do not have a clear line of defense, and every node must be prepared for encounters with an adversary. Therefore, a centralized or hierarchical network security solution does not work well. This paper provided a scalable, distributed security model for wireless Mesh networks. The model integrates the ideas of immune system and a multiAgent architecture. Compared with traditional security system, the proposed security model is designed to be distributed, of autonomy, adaptability, and scalability. In the end, the model was illustrated by an example and simulation. Related Articles | Metrics

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Study on Hybrid Sampling Inference for Dirichlet ProcessMixture of Gaussian Process Model LEI Juyang1，2，HUANG Ke1，XU Haixiang3，SHI Xizhi1 2010, 44 (02):  271-0275.  Abstract ( 4503 )   Save Dirichlet process mixture of Gaussian process model was proposed to reveal the intrinsic mechanism of multimodel of complex dynamic system architecture data. As for the difference between the mean structure and covariance structure of sparsity, parametric a priori and nonparametric a priori were designed based on the hybrid sampling framework of Polya urn sampling and overrelaxed sliced sampling. The hybrid sampling will not only be implemented under the unified MetropolisHasting probability evaluation criteria , but also be able to overcome the shortcomings of Gaussian random walk. Markov chain samples can be quickly and easily extended. The simulation results show that the hybrid sampling algorithm has more extensive adaptabilities and more accurately predictive effect than that of Gaussian process regression model and GPFR mixture model. Related Articles | Metrics

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Optimal Setting of the Threshold in Mining Process Model from Noised Log RUAN Ying1,SU Qiang1,2，4，ZHANG Guotong3,LIU Daqing3DAI Hongfang3,ZHANG Yinbin3,ZHU Yan4,XUE Lei4 2010, 44 (02):  276-0281.  Abstract ( 4377 )   Save In view of the uncertainty of the settlement of the threshold in the heuristic process mining method proposed by Aalst to deal with the noise data in the log, a method of optimization settlement of threshold based on design of experiment (DOE) analysis was proposed. The threshold is dealt as variable, and the fitness of the model that is mined as response variable, the goal is to find the most optimal combination of threshold value that will result in the most appropriate workflow model. Finally, this method was applied to mine Caesarean birth diagnosis flow. The result demonstrates that this method can find an optimal combination of threshold that result in an appropriate workflow model. Related Articles | Metrics

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A Robust Adaptive Differential Energy Video Watermarking Algorithm SHI Shusen1，SUN Tanfeng1,2，JIANG Xinghao1,2 2010, 44 (02):  282-0286.  Abstract ( 4239 )   Save This paper proposed a robust adaptive differential energy video watermarking algorithm based on Watson visual model, which uses the differential energy theory to insert robust watermark into video stream. This algorithm can control the watermark’s embedding intensity of sublow AC coefficients in the video stream adaptively through Watson visual model. And it also can choose the region to embed watermark according to the relationship between the energy’s adjustable threshold and differential energy. So watermark not only meets the nonvisual perception, but also has better robustness. The experiments show that this algorithm has strong robustness and security against the common video attacks such as noise, filter and frame attack etc. Related Articles | Metrics

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A Shared Congestion Detection Technique Based on Weighted First Order LocalRegion Method ZHANG Qingyuan1,PAN Li1,ZI Xiaochao2 2010, 44 (02):  287-0291.  Abstract ( 3943 )   Save The chaos characteristic of traffic flows in the congested network environment was utilized to develop a novel shared congestion detection method based on a weighted first order localregion arithmetic. In this method, the endtoend sample delay series of network flows are analyzed by the chaos signal process technique to quickly detect whether the network flows pass the common congestion links. The simulation results show that this method has better performance than other related methods in the network environments with long TCP, short TCP, and UDP background flows respectively. The utilization of this technique is very promising in the cooperation congestion control in peertopeer networks and the topology construction of intelligent overlay networks. Related Articles | Metrics

Communication and Transportation

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Detection of Driver’s Fatigue Based on Vehicle Performance Output LI Wei1，HE Qichang1，FAN Xiumin1,2 2010, 44 (02):  292-0296.  Abstract ( 4664 )   Save The steering wheel motion and lateral position were used to evaluate the driver’s fatigue based on the driving experiments on driving simulator. The driver’s fatigue detection system was developed by neural network. Data of ten driver’s driving experiments are collected and divided into two levels of fatigue based on the PVT (psychomotor vigilance task) testing and record video. And then, the data are processed offline to find the difference between alert and fatigue. As the input data of neural network, the steering wheel angle and lateral position should be discretized and normalized. The neural network is trained by BP algorithm until the expected error is reached. The experiment results show that this method is effective and practical to identify the driver’s fatigue level. Related Articles | Metrics