Please wait a minute...

Current Issue

    25 August 2005, Volume 26 Issue 8
    Papers
    Research on multi-agent cooperative problem solving based on grade field
    Xiao-ying WANG,Hai ZHAO,Jin-dong WANG,Wen-bo ZHANG,Zhen-yu YIN
    2005, 26(8):  1-8.  doi:1000-436X(2005)08-0001-08
    Asbtract ( 0 )   HTML ( 1)   PDF (737KB) ( 79 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A concept of grade field with CNM was introduced and correlative multi-agent model GF-CNM based on grade field was set up. Through random TOP-N algorithm, grade transition algorithm of each service agent in different grade field was depicted and analyzed. Compared with CNM, GF-CNM model can decrease network traffic and avoid additional cooperative time waste with irrelative service agent. In addition, the balance of cooperative task's load distribution can relax “Matthew effect” that the rich get richer and the poor get poorer to some degree and resolve cooperative problem solving with limited resources effectively.

    New image content authentication algorithm based on wavelet transform and morphologic
    Yan WO,Guo-qiang HAN,Jian-wei ZHANG,Bo ZHANG
    2005, 26(8):  9-15.  doi:1000-436X(2005)08-0009-07
    Asbtract ( 0 )   HTML ( 1)   PDF (1424KB) ( 56 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A new image content authentication algorithm was presented. Before transmission, the properties of image luminance and image edge-texture were analyzed according to the wavelet coefficients, then they were classified and encoded to get the characteristic value, at last the signature which derived from the encrypted characteristic value was embedded in the original image as a watermark. After receiving, the characteristic value of receiving image would be compared with the watermark draw out from the image, and the algorithm would automatically identify whether the content was tampered by the method of morphologic filter. The information of tamper location and tamper intensity could be presented at the same time. Experimental results prove that this image content authentication algorithm can effectively detect the event and the tamper location when the content of the original image was tampered, and it can tolerate some destroy produced by compression, filter, noise degraded and other image procession.

    Solving ambiguity problem of digitized multi-baseline interferometer under noisy circumstance
    Ya-qiang ZHOU,FUKan HUANG
    2005, 26(8):  16-21.  doi:1000-436X(2005)08-0016-06
    Asbtract ( 0 )   HTML ( 1)   PDF (1198KB) ( 390 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    Digitized multi-baseline interferometer had the merits of finding direction passively and high direction accuracy. But it was a conflict that enlarge maximum unambiguous direction and improving direction accuracy at the same time. To deal with such problem, stagger baselines were adopted, thus maximum unambiguous direction could be enlarged greatly. The influences the noise may have on the direction result were presented. The following problems was discussed: condition of solving ambiguous correctly; limitation for input SNR; direction accuracy and selection of stagger parameters. The maximal noisy, minimal SNR and direction range of solving ambiguous correctly were put forward.The correctness of theoretics analysis is effectively demonstrated by computer simulation.

    Signal tracking with adaptive array in impulse noise environment
    Hong TANG,Tian-shuang QIU,HANGWen-rong Z
    2005, 26(8):  22-27.  doi:1000-436X(2005)08-0022-06
    Asbtract ( 0 )   HTML ( 1)   PDF (976KB) ( 109 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    The alpha-stable process was introduced as the noise model. Based on the fractional lower order theory, subspace technique and maximum-likelihood estimator were adapted to track the propagation vector. The desired user's signal was recovered by exploiting the whole frame of received signal from impulsive environment. It could be seen that the proposed robust method offer performance improvement over the original algorithms in non-Gaussian impulsive noise, with little attendant increase in computational complexity.

    Research on asymmetric digital watermarking system
    Lei SHI,Fan HONG,Ting LUO,Xiao-qing FU
    2005, 26(8):  28-35.  doi:1000-436X(2005)08-0028-08
    Asbtract ( 125 )   HTML ( 6)   PDF (1142KB) ( 102 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    Aiming at the limitations of traditional symmetric watermarking, an asymmetric image watermarking system that offers three-level authentication for copyright protection was described. In the proposed system, the two watermarks could be publicly detected by users and third trusted party respectively, but they couldnot be forged and removed. The final authentication could be implemented by only data owner knowing the private key. The experimental results showed that the watermark has perfect detection performance and robustness against the common image processing techniques. Compared with recent asymmetric watermarking schemes, the proposed system provides a higher security level against malicious attacks, including attack on the public detector and fraudulent act of trusted third party.

    Adaptive active queue management of delay network based on fuzzy immune PID
    Yan-fei SUN,Shun-yi ZHANG,Lei ZHOU
    2005, 26(8):  36-43.  doi:1000-436X(2005)08-0036-08
    Asbtract ( 53 )   HTML ( 1)   PDF (1767KB) ( 39 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    In order to improve active queue management (AQM) algorithm's performance synthetically by enhancing algorithm's self-adapting and compensating feedback delay, a novel AQM algorithm for delay network based on fuzzy immune adaptive PID control and gray-prediction (FIGAPID) was proposed. PID parameters' online self-adapting was implemented by immune feedback mechanism, and immune feedback function was established by fuzzy nonlinear approximation. Moreover, a gray-prediction algorithm based on consistent dimension innovation was successfully introduced into feedback data's advanced prediction to compensate AQM's feedback delay. Contrasted with traditional PID algorithm, FIGAPID is validated by simulation results. It can adjust itself to new network conditions rapidly and stably, can converge to queue size-setting value, and can get lesser packets loss rate.

    Generalized relative difference set pairs and approach for the study of binary sequence pairs
    Cheng-qian XU,Juan ZHENG,Gang LI
    2005, 26(8):  44-50.  doi:1000-436X(2005)08-0044-07
    Asbtract ( 40 )   HTML ( 1)   PDF (1343KB) ( 150 )   Knowledge map   
    References | Related Articles | Metrics

    A new block design(generalized relative difference set pairs) was defined. The properties of generalized relative difference set pairs were studied. The autocorrelation of the binary sequence pairs corresponding to generalized relative difference set pairs was given. The autocorrelation of the binary sequence pairs has the same properties as the impulse. In practice the theory can expand the selecting range of perfect signal and meanwhile the theoretical basis for using generalized relative difference set pairs to study perfect binary sequence pairs is provided.

    Novel distortionless PAPR reduction scheme for OFDM system
    Guang-yue LU,Chao SHAO,HOUQuan Z
    2005, 26(8):  51-56.  doi:1000-436X(2005)08-0051-06
    Asbtract ( 41 )   HTML ( 2)   PDF (951KB) ( 39 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    Phase sequences with a special structure were designed and, thank to the special structure, the PAPR of the OFDM signal could be reduced directly in the time domain by employing the DFT property of the time domain circular convolution. The simulation results verify the effectiveness of the proposed method.

    Differential space-time modulation scheme for rapidly time-varying MIMO fading channels
    Yi-qun QIAN,Lv-xi YANG
    2005, 26(8):  57-61.  doi:1000-436X(2005)08-0057-05
    Asbtract ( 34 )   HTML ( 2)   PDF (891KB) ( 35 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    Capitalizing on the basis expansion model (BEM) for time-varying channels, a differential space-time modulation scheme was proposed for rapidly time-varying multiple-input multiple-output (MIMO) flat fading channels. The scheme employed block differential encoding, and transmitted signal matrices were diagonal and unitary. By judiciously designing interleaving at the transmitter and deinterleaving at the receiver, decision-feedback differential detection did not require channel state information. Theoretical analysis and simulation results demonstrated that the proposed scheme can achieve the maximum antenna diversity and Doppler diversity provided by time-varying channels.Key words: MIMO systems; differential modulation; basis expansion model; antenna diversity; Doppler diversity

    Method to improve the performance of blind carrier phase acquisition algorithms for high order QAM signals
    Hua XU,Hui ZHENG
    2005, 26(8):  62-66.  doi:1000-436X(2005)08-0062-05
    Asbtract ( 60 )   HTML ( 1)   PDF (467KB) ( 94 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    The existing blind carrier phase acquisition algorithms could not give a precise phase estimation, so in the phase of acquisition, the signals could't be demodulated with high quality. To overcome this problem, a new method improving the performance of acquisition algorithms was developed. First a coarse phase estimation value was given by existing acquisition algorithm, and then a maximum-likelihood iterative search was used to approach the actual value within a proper range. After several times of iterative processing, the estimation precision was improved greatly. The method to reduce the computational complexity is also proposed which can reduce the load of computation greatly while the estimation performance doesn't degrade obviously.

    Pre-processing linearly constrained LSCM multiuser detection algorithm using antenna arrays
    Hong-liang FU,Guang-zeng FENG
    2005, 26(8):  67-71.  doi:1000-436X(2005)08-0067-05
    Asbtract ( 26 )   HTML ( 1)   PDF (745KB) ( 49 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A pre-processing linearly constrained decision-feedback based on least squares constant modulus multiuser detection algorithm (PLC-DFB-LSCMA) for antenna arrays was proposed. It pre-processed the received signals from the antenna arrays and utilized the linearly constrained least squares constant modulus algorithm based on decision feedback to detect the DS-CDMA signals. The proposed algorithm was simulated and compared with DFB-LSCMA and LSCMA. Simulation results show that the proposed PLC-DFB-LSCMA is superior to the latter.

    Algorithm reducing BGP convergence time based on contrast damping
    HUKe Z,HUPei-dong Z,UXi-cheng L
    2005, 26(8):  72-77.  doi:1000-436X(2005)08-0072-06
    Asbtract ( 31 )   HTML ( 2)   PDF (592KB) ( 44 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    It was noticed that sometimes it took BGP a substantial amount of time and messages to converge and stabilize following the failure of some node in the Internet. A new algorithm was proposed that eliminated the problem pointed out. The algorithm set the brightness values for relative nodes according to the information communicated between nodes after network failure. With these brightness values it calculated the contrast value of each route and selected the feasible routes which satisfying the contrast damping to enter BGP route selection process. The algorithm can substantially reduce the convergence time and communication complexity of BGP. Finally, a simulation instance is given in order to compare with other algorithms.

    Technical Reports
    Structure for 300Mbit/s serial data recovery
    Jun YANG,Er-yang ZHANG
    2005, 26(8):  78-83.  doi:1000-436X(2005)08-0078-06
    Asbtract ( 29 )   HTML ( 1)   PDF (544KB) ( 33 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A structure for 300Mbit/s serial data recovery was advanced. Compared with the circuits in the references, this scheme can be used with less limits and achieve performance one second higher. It was proved to work well at its peak speed of 310Mbit/s serial data flow through both the software simulation and the hardware testing. This structure will have a very wide usage in high-speed data transition systems.

    Fast handoff method for mobile IP over wireless LAN
    Chun-xiao FAN,Xiao-ying ZHANG,Jie LIU,Hong-bin JIN
    2005, 26(8):  84-87.  doi:1000-436X(2005)08-0084-04
    Asbtract ( 31 )   HTML ( 2)   PDF (1087KB) ( 100 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A new latency handoff method based on the MAC layer was proposed to improve the performance of mobile IP application under wireless LAN environment. A dedicated MAC bridge was used at access points in a wireless LAN to reduce the handoff delay in the method. It can alleviate data packet loss on mobile node up and down without altering the current mobile IP specifications so that it can optimize mobile IP handoff. Its performance was evaluated in an actual network and the effectiveness of our approach was verified.

    Research on performance analysis of overloaded EWS based on ARMLinux
    Wen-bo ZHANG,Hai ZHAO,Xiao-ying WANG,Mo GUAN
    2005, 26(8):  88-93.  doi:1000-436X(2005)08-0088-06
    Asbtract ( 28 )   HTML ( 0)   PDF (574KB) ( 47 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    When an EWS overloads, packets arrive with the high speed of passion speed. MCU is almost completely used to process NIC interruption. Thus, the high-level tasks cannot be executed absolutely, with a receiving livelock occuring in EWS. For such a case, an analysis was made for the receiving process of an EWS based on ARMLinux, and the receive-packet process had been viewed as two parts, ie., the NIC interrupting process and TCP/IP process. According to the theory of 2-level serial queuing network system, an improved method -polling and closing interrupt coupled method -was proposed by means of establishing a model of receive-packet process and analyzing in detail. When the light overwork occurs, the poll method was triggered. And when the overwork was heavy, the closing Interrupt method was used. The method had been analyzed and verified through testings with an EWS based on ARMLinux.

    Study of pseudorandom binary sequence pairs
    Fei MAO,Ting JIANG,Cheng-lin ZHAO,Zheng ZHOU
    2005, 26(8):  94-98.  doi:1000-436X(2005)08-0094-05
    Asbtract ( 71 )   HTML ( 2)   PDF (870KB) ( 111 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A new periodic correlation signal was presented, which is pseudorandom binary sequence pairs.The properties of the pseudorandom binary sequence pairs were studied. For searching pseudorandom binary sequence pairs efficiently, some combined admissibility conditions were given out and many pseudorandom binary sequence pairs with small size were searched out. The pseudorandom binary sequence pairs' application were studied in detecting of code synchronization by using pseudorandom a binary sequence pairs, whose size is thirteen, as synchronous head and make a compare with Barker code whose size is also thirteen.

    Comprehensive Review
    Survey on call admission control models in wireless mobile networks
    Xue ZHANG
    2005, 26(8):  99-106.  doi:1000-436X(2005)08-0099-08
    Asbtract ( 32 )   HTML ( 0)   PDF (825KB) ( 132 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    The future generation wireless networks are expected to support both traditional data and real-time interactive multimedia traffic, and should be able to provide their users with QoS guarantees. Call admission control (CAC) plays a significant role in providing desired quality of service in wireless networks. the results on call admission control were classifed, summarized and analyzed in order to obtain the CAC model fitted for the multimedia wireless/mobile networks. To adapt to current multimedia applications, the models that combined with adaptive bandwidth allocation were emphasized. Furthermore, the CAC model combined withs pricing schemes were discussed. The introduction of economics gives us a new view to solve the problems.

    Concise Papers
    Performance of MIMO-OFDM system based on Turbo product codes over IMT2000 channels
    Ye-jun HE,Guang-xi ZHU,Wen-ming LIU,Li LI
    2005, 26(8):  107-111.  doi:1000-436X(2005)08-0107-06
    Asbtract ( 59 )   HTML ( 1)   PDF (657KB) ( 35 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    The Turbo product code(TPC) coded MIMO-OFDM system was proposed to improve the reliability of the wireless communication systems. In the proposed system, TPC with excellent error-correction performance was concatenated with space time block code(STBC).The MIMO-OFDM system with two transmit antennas and two receive antennas was tested over IMT-2000 channels, in which three types of TPC were used. The simulation results show that MIMO-OFDM system performance based on TPC is evidently improved.

    Orthogonal-beams space diversity-OFDM method for high rate mobile communications
    Yong-quan JIANG,Yuan-ping ZHOU,Xian-hua DAI,Ping LIU
    2005, 26(8):  113-116.  doi:1000-436X(2005)08-0113-04
    Asbtract ( 51 )   HTML ( 0)   PDF (685KB) ( 88 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    In order to increase the data rate of OFDM further, the orthogonal-beams space diversity-OFDM method was proposed. Firstly, employing the digital beamforming (DBF) technique of smart antennas, multiple orthogonal space-divided channels in time-domain were created, then performed OFDM demodulations for all space-divided channels, finally, obtained the frequency-domain's sequence according to the selection diversity algorithm. Both theoretical analyses and simulating results indicate that: At least there was one space-divided channel whose frequency response is superior to the isotropic-antenna channel's, furthermore, the cross-correlation between every two orthogonal space-divided channel's frequency responses was very weak, hence the frequency response of the diversity-constructed channel was obviously superior to both frequency responses of an isotropic-antenna channel and each space-divided channel. Comparing with the single antenna OFDM system, the orthogonal-beams space diversity-OFDM method can implement a higher date rate.

    Algorithm of adaptive rood pattern search using characteristic of different kinds of block in VOP
    Jin-xiang XIA,Shun-ji HUANG
    2005, 26(8):  117-121.  doi:1000-436X(2005)08-0117-05
    Asbtract ( 39 )   HTML ( 0)   PDF (416KB) ( 72 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    An algorithm of adaptive rood pattern search using the characteristic of different kinds of block (ARPS-CB-VOP) were proposed, in which the different strategy was used for different kinds of block. The blocks in VOP bounding box were classified into transparent blocks, boundary blocks, and opaque blocks. For transparent blocks, motion estimation was not needed, and was generated by the decoder. For boundary blocks, padding process in the referenced frame was not required, and its SAD (sum of absolute difference) was computed by the binary alpha planes' values. For opaque blocks, its SAD was computed by the pixels' intensities. Besides, for blocks with motion estimation, static blocks were prejudged, for moving blocks, an adaptive rood pattern search was used. The proposed ARPS-CB-VOP method improves greatly the efficiency of searching, and also the computation load is reduced remarkably with good PRSN (peak ratio of signal to noise), which is very potential.

    Optimization of LEO regional communication satellite constellation with GA algorithm
    Su-dan LI,Jiang ZHU,Guang-xia LI
    2005, 26(8):  122-128.  doi:1000-436X(2005)08-0122-07
    Asbtract ( 55 )   HTML ( 3)   PDF (858KB) ( 863 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A LEO regional communication constellation optimazation method based on modified genetic algorithm was proposed which overcomed above difficulty efficiently. First,the regional coverage constellation model was constructed, optimazation paremeters was determined and constrained according to the application backgrund of LEO constellation. Then constellation performance evaluation criterion based on grid statistic was proposed. In order to improve calculation accuracy of optimization, a mixed genetic algorithm was proposed, in which complex algorithm and parameter region ajusting was introduced. An integrated constellation optimazation was constructed after applying this algorithm to constellation model. Good result can be achieved by appling this method to a detailed constellation example.

    Correspondences Speech source
    Speech source 2D DOA estimation algorithm based on random microphone array
    UTai-liang J,ENGQi-cong P,HAOHuai-zong S,INJing-ran L
    2005, 26(8):  129-133.  doi:1000-436X(2005)08-0129-05
    Asbtract ( 131 )   HTML ( 4)   PDF (1147KB) ( 600 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    The speech source localization technology based on microphone array had been researched and a far-field signal model based microphone array was obtained. The two dimensions (2D, plane angle and polar angle) speech source DOA estimation algorithm had been proposed by combining this model and subspace methods. Using the MATLAB, several type of array structure was contrastively analyzed. Two kinds of new microphone array, 3D uniform spherical surface array and 3D uniform linear array were designed to 2D-DOA estimation because of ambiguity DOA of the uniform linear microphone array. Simulation results show the high performance of the DOA estimation is given when the proposed algorithm is used in planar uniform circle array, 3D uniform spherical surface array and 3D uniform linear array.

    Analysis of MIMO channel capacity for distributed antenna system
    Han-qiang LI,Wei GUO,Hui ZHENG
    2005, 26(8):  134-138.  doi:1000-436X(2005)08-0134-05
    Asbtract ( 55 )   HTML ( 5)   PDF (1331KB) ( 848 )   Knowledge map   
    Figures and Tables | References | Related Articles | Metrics

    A distributed MIMO system combining the characteristics of MIMO channel and distributed antenna system was proposed. Channel model considered the influences of path loss, fast fading and lognormal shadowing. First, MIMO channel capacity between distributed antenna (DA) systems and conventional centralized antenna (CA) systems were compared. Through the comparison, it was found that the DA systems could acquire equal coverage property in the cell, and achieve a better channel capacity than CA systems. Following that, two different power allocation strategies were analyzed for downlink. The numerical results show that, because of the knowledge of the MIMO channel, water-filling power allocation strategy can achieve a channel capacity increment of about 0.25bit/(s·Hz) per transmission antenna.

Copyright Information
Authorized by: China Association for Science and Technology
Sponsored by: China Institute of Communications
Editor-in-Chief: Zhang Ping
Associate Editor-in-Chief:
Zhang Yanchuan, Ma Jianfeng, Yang Zhen, Shen Lianfeng, Tao Xiaofeng, Liu Hualu
Editorial Director: Wu Nada, Zhao Li
Address: F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
Post: 100079
Tel: 010-53933889、53878169、
53859522、010-53878236
Email: xuebao@ptpress.com.cn
Email: txxb@bjxintong.com.cn
ISSN 1000-436X
CN 11-2102/TN
Visited
Total visitors:
Visitors of today:
Now online: