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    20 June 2012 Volume 39 Issue 3
      
    Original Articles
    Design and analysis of large displacement hybrid system
    MING Zhengfeng;WEN Tao;LEI Zhenya;WEN Rui;WANG Hao
    J4. 2012, 39(3):  1-6+13.  doi:10.3969/j.issn.1001-2400.2012.03.001
    Abstract ( 1533 )   PDF (1350KB) ( 1078 )   Save
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    A new electromagnetic levitation system device is proposed, which uses the electromagnet array and the permanent magnet to provide three-dimensional electromagnetic levitation force. The system has the advantages of the large suspension force, the distribution magnetic field and wide range movement over the traditional electromagnetic suspension system, and it can significantly improve the efficiency of the system. The characteristics and the synthetic magnetic properties of the magnetic levitation force are analyzed by the finite element method before the relevant experiments. The results show that the suspension system so designed can be used for the large air gap with good stability and control.

    Efficient intra-frame coding algorithm for the  depth image in 3D video
    YANG Xu;CHANG Yilin;HOU Junyan; YUAN Hui;LI Bingbing;CHEN Tao
    J4. 2012, 39(3):  7-13.  doi:10.3969/j.issn.1001-2400.2012.03.002
    Abstract ( 1230 )   PDF (1116KB) ( 1026 )   Save
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    An efficient depth image intra-frame coding method based on the dependency of the video and the depth image is proposed to reduce the complexity of the depth image intra-frame coding. In the proposed method, the optimum intra-frame coding mode of video is used to predict the optimum intra-frame mode of depth image coding in order to simplify the process of Rate-Distortion Optimization (RDO) and reduce the computation of the Lagrangian cost function in intra-frame prediction in depth image coding. Simulation results show that the proposed method can reduce the coding time by 37.16% on average compared with the independent coding method of depth images, while maintaining high virtual rendering performance.

    Study of three-channel spaceborne SAR-DPCA moving target detection with the slant-placed baseline
    XIA Meng;YANG Xiaoniu
    J4. 2012, 39(3):  14-19+26.  doi:10.3969/j.issn.1001-2400.2012.03.003
    Abstract ( 1082 )   PDF (3346KB) ( 965 )   Save
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    In order to obtain a number of pieces of horizontal and vertical phase center information, a novel three-channel spaceborne SAR-GMTI is proposed, based on the slant-placed baseline and displaced phase center antenna. The compensation function for the equivalent phase center with the slant-placed baseline is analyzed. The new constraint of the system and the analysis of the blind velocity relative to the slant-placed antenna are also given. Displaced phase center antenna technology is presented for moving target detection and interferometry technology is applied for position after channel compensation. Finally, simulation results confirm the effectiveness of this method with the slant-placed baseline.

    Hexagonal centralized cluster-based multi-hop routing protocol for WSN
    LI Zhen;CHEN Jian;KUO Yonghong
    J4. 2012, 39(3):  20-26.  doi:10.3969/j.issn.1001-2400.2012.03.004
    Abstract ( 1226 )   PDF (625KB) ( 1036 )   Save
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    For random distribution of large-scale wireless sensor networks (WSNs), a hexagonal centralized cluster-based multi-hop routing protocol (HCCM) is proposed. The base station divides clusters with the lowest energy consumption by choosing the length of a hexagon, and then optimizes clusters according to the number of nodes in practice. Based on the received energy information, the cluster head and multi-hop transmission path are determined with suitable slots being allotted to transmit data. Simulation results show that compared with the low energy adaptive cluster hierarchy (LEACH) and differential evolution-based routing algorithm (DE_LEACH), this protocol prolongs the network life with fewer packets being received in the small scale network. But in large scale networks, this protocol prolongs the network life by 15% and receives 9.5% more packets compared with the energy-efficient clustering technique(EECT), thus improving the network performance, which verifies that this protocol is suitable for large-scale WSNs.

    Relay selection and power allocation for the uplink in cooperative cellular networks
    GUO Chaoping;HAN Kun;ZHANG Xiaolong; LI Yongzhao;ZHANG Hailin
    J4. 2012, 39(3):  27-33+42.  doi:10.3969/j.issn.1001-2400.2012.03.005
    Abstract ( 1478 )   PDF (587KB) ( 1038 )   Save
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    An assignment model of uplink resources, namely, power and relay, is proposed to minimize the total cost of energy-constrained cooperative networks. The model is a non-linear constraint, 0-1 integer programming problem. An adaptive resource allocation scheme is presented to solve it, which selects the relay with the lowest total cost for each source from the given relay set. A graphic-theory-based optimal power allocation algorithm is presented to minimize their total cost for a given source-relay pair. Simulation and analysis show that the scheme is suboptimal and can transmit more data than other algorithms and prolong network lifetime.

    Scheme for cross-layer seamless handover between HeNB and WLAN in the roaming scenario
    LAI Chengzhe;LI Hui;ZHANG Yueyu;CAO Jin
    J4. 2012, 39(3):  34-42.  doi:10.3969/j.issn.1001-2400.2012.03.006
    Abstract ( 1324 )   PDF (1183KB) ( 1103 )   Save
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    Home eNodeB (HeNB) is a small, low-power cellular base station, mainly used for indoor wireless access. During the period of coexistence of WLAN and HeNB, inevitable handover will occur between them in a certain region. To integrate these two technologies better, we propose a scheme for cross-layer seamless handover between HeNB and WLAN in the roaming scenario. The proposed scheme uses the basic idea of pre-registration and performs the pre-authentication process before layer 2 handover to reduce handover delay. In addition, it uses packet buffering and forwarding functions in order to reduce packet loss during the handover period. Detailed signaling procedures are presented. Finally, a detailed comparison is made in the signaling cost, the handover latency and the packet loss. The results of analysis illustrate that the proposed scheme achieves better performance compared to several other schemes.

    Change detection in multi-temporal remote sensing images based on the wavelet-domain hidden Markov chain model
    XIN Fangfang;JIAO Licheng;WANG Guiting;WAN Honglin
    J4. 2012, 39(3):  43-49.  doi:10.3969/j.issn.1001-2400.2012.03.007
    Abstract ( 1483 )   PDF (4545KB) ( 948 )   Save
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    The traditional threshold algorithms detect the changes in multitemporal remote sensing images based on the analysis of the signal function model, which has a poor accuracy for difference images with complex distribution. In this paper, a new approach is proposed by virtue of the double Gaussian mixture model and the wavelet transform. The proposed algorithm has better matching than the signal function model and introduces the spatial information by using the wavelet transform. After using the double Gaussian mixture models to detect the changed regions, the change maps in different scales are fused using the HMC model based on sequential maximum a posteriori estimation. The experiments on the real remote sensing images confirm the effectiveness of the proposed algorithm.

    Greedy adaptive recovery algorithm for compressed sensing
    GAN Wei;XU Luping;ZHANG Hua;SU Zhe
    J4. 2012, 39(3):  50-57+79.  doi:10.3969/j.issn.1001-2400.2012.03.008
    Abstract ( 1575 )   PDF (3257KB) ( 1311 )   Save
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    In order to optimize the performance of Compressive Sampling Matching Pursuit (CoSaMP), the Compressive Sampling Modifying Matching Pursuit greedy adaptive algorithm (CoSaMMP) is proposed. Compared with the original CoSaMP, the algorithm adopts the fuzzy threshold preliminary rule with theoretical guarantee to avoid using apriori information on signals in the primary election phase, sets the initial pruning threshold to reduce unnecessary iterations, improves the pruning mode to enhance the recovery accuracy and avoid using apriori information on signals in the pruning phase, and finally realizes adaptive recovery for compressible signals. Simulation results show that for the same sparsity level, the operation speed of CoSaMMP increases by 2 fold compared with the initial algorithm, and that the required measurement number decreases about 1%, In addition, under the conditions of the high sparsity level, the algorithm have the better anti-interference ability than the initial one.

    Low power Turbo decoder based on the state metric decimation and interpolation strategy
    LI Xiaofeng;FENG Dazheng;HU Shukai
    J4. 2012, 39(3):  58-62+71.  doi:10.3969/j.issn.1001-2400.2012.03.009
    Abstract ( 1105 )   PDF (763KB) ( 951 )   Save
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    A novel forward and backword state metric calculation and the memory management strategy are presencted for the turbo decoder which adopts the Log-MAP(Maximum A-Posteriori) algorithm. By the way of decimating the forward state metric first and then interpolating in the LLR(Log Likelihood Ratio) computation stage to reduce the state metric memory size, which acquires significant power and area benefit with ignorable computation penalty. And the soft in soft out(SISO) scheduling and control mechanism are also addressed for supporting our proposed optimization architecture. Compared with the conventional memory management strategy our design could reduce the state metric size by 80% with the sliding window 128. Based on our proposed architecture an HSDPA turbo decoder is realized by the 65nm CMOS standard cell library with the frequency of 350MHz and the voltage of 1.18V. The result achieves 21.4Mbit/s throughput and 29.3mW power consumption, and an energy efficiency of up to 0.171nJ/bit/iteration.

    Translational motion compensation for ISAR imaging based on joint autofocusing under the low SNR
    YANG Lei;XIONG Tao;ZHANG Lei;XING Mengdao
    J4. 2012, 39(3):  63-71.  doi:10.3969/j.issn.1001-2400.2012.03.010
    Abstract ( 1426 )   PDF (4822KB) ( 1045 )   Save
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    In conventional inverse synthetic aperture radar (ISAR), since range alignment can not be accurately performed in low signal-to-noise (SNR) environment, the subsequent phase adjustment will be limited in precision. To address this problem, a novel autofocusing method is proposed, which is capable of correcting both range shift and phase disturbance. It can compensate the translational motion in a complex form for ISAR data contaminated with strong noise. The method utilizes the entropy of the ISAR image as the optimization function, and the Damped Newton algorithm is applied to solve the problem efficiently. According to the fact that the translational motion can be usually fitted by limited-order polynomial, the normalized polynomial fitting technique is applied to enhance both the efficiency and precision of the proposal. Finally, real data of Yak-42 are used to validate the effectiveness and reliability of the proposed method under the low SNR.

    New method of deriving the spectrum for general bistatic SAR processing
    LIU Yuchun;WANG Jun;LI Hongwei
    J4. 2012, 39(3):  72-79.  doi:10.3969/j.issn.1001-2400.2012.03.011
    Abstract ( 997 )   PDF (1173KB) ( 939 )   Save
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    To improve the accuracy of the bistatic point target reference spectrum(BPTRS), a new method of deriving the spectrum is poposed.An optimal square approach technique is employed to handle the double square root of two range histories. The point of stationary phase is derived by solving the polynomial equation. Finally an accurate BPTRS is consequently formulated. Simulation results show that the spectrum estimation of the proposed method has a better focusing performance.

    High-performance CMOS current-mode Winner-take-all circuit
    DAI Li;ZHUANG Yiqi;JING Xin;TANG Hualian
    J4. 2012, 39(3):  80-85.  doi:10.3969/j.issn.1001-2400.2012.03.012
    Abstract ( 1226 )   PDF (879KB) ( 1000 )   Save
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    A novel CMOS current-mode Winner-take-all (WTA) circuit is presented. The design utilizes a regenerative circuit to improve the resolution and speed. Without using any current mirror, a rectifier circuit is used to output the current, which improves the precision of the output current. Different from conventional WTA designs with a binary-tree structure, a new concurrent N-input WTA structure is also proposed. An 8-input WTA is implemented using TSMC 0.18μm technology. The design is evaluated and compared with the well-known WTA benchmark circuits. Simulation results show that proposed design can provide a resolution of 1nA and a precision of 99.99%, and at the same time provide the compactness and low power. It is ideal for a variety of embedded intelligent applications.

    Scattering rates of electrons in strained Si1-xGex (100)
    ZHAO Lixia;ZHANG Heming;XUAN Rongxi;HU Huiyong
    J4. 2012, 39(3):  86-89+105.  doi:10.3969/j.issn.1001-2400.2012.03.013
    Abstract ( 1253 )   PDF (501KB) ( 908 )   Save
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    Based on Fermi's golden rule and the theory of Boltzmann collision term approximation, scattering rates of electrons in strained Si1-xGex /(100)Si is studied, including the ionized impurity, acoustic phonon, intervalley phonon and alloy disorder scattering rates. It is found that scattering rates of acoustic phonons and f2 and f3 intervalley phonons decrease obviously under strain. One of the two factors which lead to the electron mobility enhancement in Si-based strained materials is the electron scattering rate.

    Cooperative GBN-ARQ with a single buffer
    DONG Luobing;SHEN Peiyi;YI Kechu;YU Quan
    J4. 2012, 39(3):  90-94.  doi:10.3969/j.issn.1001-2400.2012.03.014
    Abstract ( 1433 )   PDF (567KB) ( 920 )   Save
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    This paper presents a Cooperative Go-Back-N Automatic Repeat Request Algorithm with a Single Buffer (SBC-GBN-ARQ), which can be applied to the multi-access based single source single relay wireless networks. Adding one single buffer at the destination by virtue of the characteristic of a multiple access system(e.g. TDMA or CDMA), the scheme enables both the source and the relay to participate in the first transmission and the retransmission process of packets, which makes the system yield a much better throughput performance than GBN-ARQ algorithm. It can overcome the drawback of the conventional algorithm that its data throughput will sharply drop down when the channel condition is getting poorer. Numerical analysis and computer simulation show that the proposed algorithm significantly outperforms the conventional one in throughput efficiency, and that the maximum gain is over 10dB under some conditions.

    Structure of the edge background clutter metric
    LI Qian;ZHANG Jianqi;YANG Cui
    J4. 2012, 39(3):  95-99+130.  doi:10.3969/j.issn.1001-2400.2012.03.015
    Abstract ( 1266 )   PDF (2645KB) ( 850 )   Save
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    Based on the fact that the recognition of a target depends mainly on the structure feature for human vision, the structure of the edge background clutter metric is proposed, by describing the similarity between background and target by their difference in the distribution of the edge structure. Compared to the others, it is available for various scenes by statistically computing the properties of the target and background's structure to emphasize the importance of the structure and weaken the influence of scene illumination on target recognition. Experiment shows that its prediction correlates well with the detection probability of human visual systems.

    Efficient implementation of the CAVLC entropy encoder based on FPGA
    CHU Xiuqin;WU Shuo;CHANG Fang;HE Wenqing
    J4. 2012, 39(3):  100-105.  doi:10.3969/j.issn.1001-2400.2012.03.016
    Abstract ( 1335 )   PDF (870KB) ( 960 )   Save
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    Since the Context_based Adaptive Variable Length Coding (CAVLC)algorithm in H.264 has both high complexity in computation and great difficulty in real-time implementation, a high efficient architecture for this algorithm is presented. In this design, realization of encoding on different types of data blocks in the block stream sourced from the decomposition of a macro block data conquers the limitation in conventional schemes where only one type of data blocks can be processed. Replacement of zig_zag scan for reverse zig_zag scan in the upstream module results in the elimination of reverse operation and a great rise in efficiency of the CAVLC module with no increase of computation in the upstream module. Finally, results of its verification and realization on FPGA indicate that this structure has as high a maximum coding system frequency as 147.78MHz, the first coding delay of 32 clock cycles, and a throughput delay of 16 clock cycles, thus adequately meeting the requirement for high-definition and real-time applications.

    Calculation and application of the mutual impedance and the scattering matrices of large finite arrays
    ZHANG Shuai;GONG Shuxi;GUAN Ying;GONG Qi;LU Bao
    J4. 2012, 39(3):  106-113.  doi:10.3969/j.issn.1001-2400.2012.03.017
    Abstract ( 1309 )   PDF (1894KB) ( 1098 )   Save
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    The relationships among the radiation pattern, mutual impedance and scattering matrices of array antennas are derived. Based on the expressions, a novel approach is presented to calculate the mutual impedance and the scattering matrices of an array utilizing commercial simulation software HFSS. In addition, an efficient and accurate method is proposed to calculate and synthesize the radiation pattern of large finite arrays. In this method, the mutual impedance matrix of the large array is deduced from a small array ignoring the coupling beyond the small array size. Once the mutual impedance matrix is obtained, the radiation pattern of the large array can be computed using the derived equations. In order to assess the accuracy and efficiency of the proposed method, an example array of 16 microstrip patch antennas is optimized with the genetic algorithm (GA) to minimize the maximum sidelobe level of the radiation pattern. Calculated results agree well with those simulated by HFSS.

    Synthesis of a conformal antenna array using the competition differential evolution strategy
    LI Rui;SHI Xiaowei;XU Le;GU Xintao;LI Ping
    J4. 2012, 39(3):  114-119.  doi:10.3969/j.issn.1001-2400.2012.03.018
    Abstract ( 1434 )   PDF (1330KB) ( 992 )   Save
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    With the novel mutant operation adopting the sub-optimal individual, a Competition Differential Evolution (CDE) algorithm is proposed. The convergence speed of CDE is accelerated with the aid of the sub-optimal individual. Typical test functions are minimized using DE and CDE algorithms to verify the performance of the CDE algorithm. Low sidelobe broad nulls and multi-beam cylinder conformal antenna arrays are synthesized by the algorithm. Simulation results show that the proposed algorithm converges faster than DE.

    Application of the high impedance surface for RCS reduction of the antenna
    GONG Qi;ZHANG Shuai;GONG Shuxi;JIAO Yongchang;LU Bao
    J4. 2012, 39(3):  120-125.  doi:10.3969/j.issn.1001-2400.2012.03.019
    Abstract ( 1186 )   PDF (3826KB) ( 1112 )   Save
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    This paper investigates the application of the high impedance surface (HIS) to reduce the radar cross section (RCS) of the antenna. The HIS elements are fabricated on the same surface together with the antenna. Around the operational frequency of the HIS elements, the reflection of the HIS and PEC have the opposite phases, so for any normal incident plane wave the reflections cancel out, thereby reducing the RCS. Thus the HIS can be used to reduce the RCS of the antenna which has a PEC surface radiator. To assess the validity of the proposed method, the HIS is employed to reduce the RCS of two microstrip patch antennas. Simulated and measured results show that the RCS in-band of the two microstrip patch antennas with HIS is reduced by at least 5.3dB compared with the common antennas, with the impedance bandwidth (S11<-10dB) not changed.

    Automatic matching algorithm for the latent semantic analysis based supply and demand information
    FENG Yuejin;ZHANG Fengbin
    J4. 2012, 39(3):  126-130.  doi:10.3969/j.issn.1001-2400.2012.03.020
    Abstract ( 1314 )   PDF (477KB) ( 1096 )   Save
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    In traditional Supply and Demand Information Matching models, a word is regarded as an independent unit. However, there are many synonyms and polysemy in the natural language and their existence has deteriorated the precision. In order to solve this problem, Latent Semantic Analysis is applied to it. Moreover, an algorithm based on Entropy is proposed to improve the weighting of Latent Semantic Analysis. A Supply and Demand Information Automatic Matching algorithm based on Latent Semantic Analysis, Rule Extraction and Relevance Feedback is realized. And a Supply and Demand Information Base is designed to support it. Experimental results show that the precision of this algorithm is much better than that of the method based on the Vector Space Model.

    Optimized generalized complex exponential basis expansion in the OFDM system
    ZHANG Qinjuan;WU Muqing;GUO Qilin;ZHANG Rui
    J4. 2012, 39(3):  131-135.  doi:10.3969/j.issn.1001-2400.2012.03.021
    Abstract ( 1442 )   PDF (464KB) ( 1016 )   Save
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    In wireless communication systems, high-speed mobile terminals induce the channel to be time selective. In this paper, the generalized complex exponential basis expansion model (GCE-BEM) is optimized for the time selective channel of the orthogonal frequency division multiplexing system. The proposed model can adapt the model coefficient according to the Doppler frequency estimation situation, becoming the GCE-BEM with a fixed or varying coefficient. It can effectively eliminate high-frequency noise without increasing the computational complexity, reduce the model error, and improve the system performance.

    Adaptive neighbor selection method for the  P2P media streaming system
    FENG Zhentan;NI Hong;WANG Jinlin;YOU Jiali
    J4. 2012, 39(3):  136-143.  doi:10.3969/j.issn.1001-2400.2012.03.022
    Abstract ( 1106 )   PDF (682KB) ( 1068 )   Save
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    Taking into consideration the heterogeneity among peers, an adaptive neighbor selection method is proposed based on peer dynamic capacity. Firstly, in order to analyze the dynamic capacity, a model for the P2P streaming system is presented. According to the model, peers are divided into different levels based on their capacities. Secondly, a random walk process is applied for the purpose of searching the neighbor. The peer is added to the candidate neighbor list when the random walk process ends. In order to guarantee that the candidate neighbors have a high capacity, the expected stationary distribution for the random walk is adjusted according to the peers' dynamic capacity. The transition probability matrix is calculated by the Metropolis-Hastings methods in order to satisfy the expected stationary distribution. Moreover, the neighbors' updated method,  and join and departure process are elaborated to ensure the node load balance and system stability. Simulation results demonstrate that the algorithm can significantly improve system performance, reduce system latency, and is very robust in dynamic network environment.

    Method for constructing QC-LDPC codes using the dayan sequence
    ZHU Leiji;WANG Han;SHI Yusong;XING Tao;WANG Yingguan
    J4. 2012, 39(3):  144-148+160.  doi:10.3969/j.issn.1001-2400.2012.03.023
    Abstract ( 1350 )   PDF (446KB) ( 1013 )   Save
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    For the purpose of constructing a channel coding solution with excellent performance, we present a method to construct Quasi-Cyclic Low-Density Parity-Check Codes based on the Dayan Sequence by analysing its characteristic. By making use of the feature that the fixed sequence difference in the Dayan Sequence has a steady increase value, this method is used to construct a parity check matrix that has no circle of length four, with the structure of quasi cyclic, and needs little storage space. Simulation results show that, under 10-5 BER, in the Additive White Gaussian Noise channel and Rayleigh fading channel, QC-LDPC based on the Dayan Sequence has a gain nearly 1dB  more than that by QC-LDPC based on the Fibonacci Sequence. Also, in the Additive White Gaussian Noise channel, it has a gain almost 3dB  more than that by array LDPC.

    IP protocol identification method using the pattern match and check sum
    YANG Jie;LIU Congfeng
    J4. 2012, 39(3):  149-153+165.  doi:10.3969/j.issn.1001-2400.2012.03.024
    Abstract ( 1106 )   PDF (497KB) ( 1063 )   Save
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    In order to reduce the probability of report mistakes and pretermission which is likely to happen, and to improve the nicety of explicating application-level protocols in an intrusion detection system, a method is proposed to identify the IP protocol using the pattern match algorithm and IP header check sum calculation for Ethernet data packs. Firstly, Ethernet data packs are matched with some static characters of the IP header in the proposed method, and then IP protocol check sum calculation is done. As a result, whether the type that the data packs belong to is IP protocol or not can be identified finally. Under the Visual C++software condition, simulations prove the validity and reliability of the proposed method by running the simulated programme based on the data swatch which has been listed. And so the correctness of identifying upper protocols in the future is able to be ensured.

    Novel face recognition relevance feedback algorithm for video
    LU Ke;DING Zhengming;ZHAO Jidong;WU Yue
    J4. 2012, 39(3):  154-160.  doi:10.3969/j.issn.1001-2400.2012.03.025
    Abstract ( 1164 )   PDF (1653KB) ( 945 )   Save
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    How to fully utilize both spatial and temporal information in video to overcome the difficulties existing in the video-based face recognition, such as the low resolution of face images in video, large variations of face scale, radical changes of illumination and pose as well as occasional occlusion of different parts of faces, is the key problem. In this paper, on the basis of Locality Preserving Projections (LPP), we propose a novel relevance feedback video face recognition method (RFVLPP), which can preserve more spatial and temporal information hidden in the video face sequence using clustering, and make full use of the intrinsic nonlinear structure information to extract discriminative manifold features. The experiment compares RFVLPP with other algorithms on UCSD/Honda Video Database and our own Video Database. Experimental results show that the proposed approach can outperform state-of-the-art solutions for video-based face recognition.

    Miniaturized broadband and high gain metamaterial patch antenna
    LIU Tao;CAO Xiangyu;GAO Jun;YANG Qun;LI Wenqiang
    J4. 2012, 39(3):  161-165.  doi:10.3969/j.issn.1001-2400.2012.03.026
    Abstract ( 1166 )   PDF (1593KB) ( 1109 )   Save
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    A miniaturized broad bandwidth and high-gain patch antenna is designed and fabricated using the metamaterial concept via the periodically loaded complementary split-ring resonators(CSRRs) on the upper patch and strip-line gaps on the bottom ground plane, respectively. The novel antenna has a much lower resonant center frequency which is obviously reduced about 36.4%, a wider bandwidth which is significantly broadened from about 2.9% to about 39.9%, and also a lower voltage standing wave ratio than the original antenna. Experimental data show a reasonably good agreement between the simulation and measured results. Also, due to the left-handed characteristics of the metamaterial, the effective medium parameters of the substrate of the antenna are affected, which induces the strongest radiation in the horizontal direction instead of the vertical direction of the conventional patch antenna.

    Modeling of the throughput of CMT in heterogeneous networks
    ZHENG Yanwei;NI Hong;LIU Lei
    J4. 2012, 39(3):  166-171+184.  doi:10.3969/j.issn.1001-2400.2012.03.027
    Abstract ( 1139 )   PDF (713KB) ( 1042 )   Save
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    Based on analyzing the characteristics of concurrent multipath transfer (CMT), this paper proposes a throughput modeling method for CMT in heterogeneous networks. In order to estimate the throughput of CMT, it uses the state transition probability matrix to analyze the growth mechanisms of the congestion window in the slow-start and congestion avoidance stage of each path. It also puts forward an optimization algorithm, which reduces the complexity of the model by merging the states with the same congestion window size and adding the corresponding state transition probabilities. Experimental results show that the proposed method can accurately estimate the throughput of CMT even if the paths have different features, and that it can work well under the heterogeneous network environment.

    Coordinated multi-point transmission with limited feedback and channel delay
    SHI Junfeng;ZHANG Tiankui;ZENG Zhimin
    J4. 2012, 39(3):  172-177.  doi:10.3969/j.issn.1001-2400.2012.03.028
    Abstract ( 969 )   PDF (528KB) ( 902 )   Save
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    Based on clustered base station (BS) coordination and the channel delay and limited feedback in practical systems, the expressions for the data rate and rate loss upper bound per cell are derived with imperfect channel state information (CSI). Thus, given the affordable rate loss, the minimum number of feedback bits can be calculated using the upper bound. Duo to the fact that this value is derived from the upper bound, it is not very accurate. Numerical results show that the rate loss reduces when the number of feedback bits increases and the channel delay decreases. On the other hand, when the channel delay increases gradually, the rate loss can be improved little by the increase of feedback bits. Meanwhile, as SNR increases, the system performance with the imperfect CSI improves more slowly than that with the perfect CSI.

    Disjoint nodes multipath routing algorithm for WSN
    YANG Jungang;SHI Haoshan;DUAN Aiyuan;MA Chao;WANG Qingwen
    J4. 2012, 39(3):  178-184.  doi:10.3969/j.issn.1001-2400.2012.03.029
    Abstract ( 1348 )   PDF (560KB) ( 972 )   Save
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    How to find the multi-path route with disjoint nodes, as a valid way to improve the energy efficiency and reliability of networks, can greatly save network resources. This paper proposes a disjoint multi-path routing of WSN, named DMPRW. In this algorithm, all nodes are distributed into different hop layers in terms of the number of hops to the s node, and the sink node starts the route process by broadcasting the routing message to all nodes from layer to layer. At last, DMPRW builds many disjoint paths to sink for each node. The loop free and disjoint route characteristics are proved theoretically, and traffic and energy balance are ensured. Finally, DMPRW is embedded in the DD (Directed Diffusion) protocol, and simulation results show that DMPRW can lead to higher reliability and energy efficiency than the traditional single path DD protocol.

    Compensation of the clutter spectrum for airborne forward-looking radar based on the Bessel series expansion
    JIANG Hui;LU Guangyue
    J4. 2012, 39(3):  185-189+195.  doi:10.3969/j.issn.1001-2400.2012.03.030
    Abstract ( 991 )   PDF (1010KB) ( 852 )   Save
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    The clutter spectrum depends highly on the range for forward-looking radar, which results in the heterogeneous ground clutter in space-time adaptive processing (STAP). According to the clutter model, a novel method is proposed. The method firstly uses the Bessel function to separate the azimuth from the elevation, and the spatial-time steering vector could be represented as the azimuth and elevation vector kronecker product to each range gate. Secondly, a transform matrix could be obtained by projecting the training unit of the elevation vector to the tested, which is applied to process the data at a given Doppler gate, and eliminate the heterogeneous ground clutter and generate a sufficient data to construct the new covariance matrix. Finally, the conventional STAP could be applied to the clutter suppression. Simulation results verify the effectiveness of the proposed method.

    Design of the switch-mode two-compensatory semiconductor laser temperature control power supply
    LIU Tanping;WANG Zhaoba;LIU Weiqi
    J4. 2012, 39(3):  190-195.  doi:10.3969/j.issn.1001-2400.2012.03.031
    Abstract ( 1118 )   PDF (1690KB) ( 1017 )   Save
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    A semiconductor laser temperature control power supply is designed, combined with switch mode conversion and PID regulation technology, which is used to drive a TEC(thermoelectric cooler) in the semiconductor Laser Diode for controling its temperature. Due to the use of unique two compensatory technology, firstly we obtain a good dynamic response, and then reduce the volume of the temperature control power supply evidently and improve the conversion efficiency; at the same time the output voltage and current can be regulated smoothly instead of PWM regulation mode, and to solve the problem of switch mode power supply will suit the request of temperature control with difficulty. We discard the PWM output mode which does not suit temperature control. The volume of power supply by the new design way is 10 percent of the primary version and  the input power is 20 percent of the primary version, so the new semiconductor laser temperature control power supply is very suitable to being used in laser televsion.

    Topological graph based tag semantic relatedness measure for social tagging systems
    ZHANG Changli;HOU Ronghui
    J4. 2012, 39(3):  196-201.  doi:10.3969/j.issn.1001-2400.2012.03.032
    Abstract ( 1123 )   PDF (970KB) ( 971 )   Save
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    Regarding the problems of the structureless organization and implicit meaning of tags in the social tagging systems in Web2.0, a topological graph based formal model of semantic relatedness measure is proposed to fully exploit the interplay of the semantic co-relations among a large number of tags. In this model, the results of the statistics based tag relatedness measures are used to extend the topological graph of tags co-occurrence network with weights of edges, two operators are invented to synthetically compute the overall effect of the weights within the extended graph, so that the interplay of semantic co-relations of tags can be explicitly represented and the semantic relatedness of tags can also be measured soundly. To illustrate the calculating process and to testify the validness and feasibility of the calculating results for this model, an experiment is conducted with the set of the most popular tags crawled from Flickr.com, a famous photos sharing website. Experimental results show that the model can lead to better results, and is highly applicable to the guidance and constraint of annotating behaviors in Web2.0 environments.

    Dynamic bandwidth allocation algorithm according to controlling call-blocking probabilities proportion
    ZHAO Haijun;LI Min;CUI Mengtian;LI Mingdong
    J4. 2012, 39(3):  202-208.  doi:10.3969/j.issn.1001-2400.2012.03.033
    Abstract ( 1225 )   PDF (556KB) ( 999 )   Save
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    For achieving more effectively dynamic resource allocation, a dynamic bandwidth allocation algorithm is proposed using complete partitioning (CP) technology in a single communication link by analysing dynamic bandwidth allocation in a common link. On the basis of forecasting the influence of call-blocking probabilities on the transient response,the algorithm proposed in this paper controlls call-blocking probabilities proportion between different Classes-of-Service (CoSs) of non-stationary traffic with variable size bandwidth requests, consequently achieving optimal utilization of the bandwidth. Simulation shows that the capacities can be dynamically allocated in a nonstationary traffic environment by adopting the proposed algorithm. And it can also allocate the bandwidth much more effectively,while enhancing greatly the utilization ratio of the bandwidth, reducing the average polling time.

    Fabrication of the uniaxial stained SOI wafer by mechanical bending
    DAI Xianying;WANG Lin;YANG Cheng;ZHENG Ruochuan;ZHANG Heming;HAO Yue
    J4. 2012, 39(3):  209-212.  doi:10.3969/j.issn.1001-2400.2012.03.034
    Abstract ( 1337 )   PDF (969KB) ( 933 )   Save
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    Based on the theory of elasticity and the mechanical properties of SOI, this paper puts forward a new method to produce the uniaxially strained SOI wafer, and describes the principle of the process. The 4-in. Silicon-On-Insulater wafer under goes the mechanical-bended test on the pedestal whose curvature radius is 0.75m, and then it is annealed at 250℃ for 20 hours to achieve the uniaxial strain. The IR-transmission-unaffected-diffraction instrument and Raman spectrum instrument are used for study of the pre-bonding quality and strain degree. The frequency shift of the Raman spectrum is 520.3cm<sup>-1<sup>.The Si peak of the strained Si layer is shifted by -0.3cm<sup>-1<sup> compared to the typical value. It is indicated that a compressive uniaxial strain can be obtained after bending and annealing. The comparative strain is 0.077%, higher than the value of 0.059% in the literature.