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    25 June 2006, Volume 27 Issue 6
    Academic paper
    Distributed multicast algorithm for building an energy-efficient shared tree in ad hoc networks
    Yu-hong LUO,Jian-xin WANG,Song-qiao CHEN
    2006, 27(6):  1-9.  doi:1000-436X(2006)06-0001-09
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    To extend shared tree lifetime,a distributed algorithm D-REMiT was proposed for building an energy-efficient shared tree in ad hoc networks. In D-REMiT algorithm,both the total energy consumption (TEC) and System Lifetime (SL) were taken into account while building the shared tree. The simulation results show that the D-REMiT improves SL of shared tree efficiently with little sacrifice on TEC and has good convergence,and it has better performances than G-REMiT in ad hoc networks.

    Frequency offset estimator for OFDM with time-frequency training sequence
    Yan-xiang JIANG,Dong-ming WANG,Xi-qi GAO,Xiao-hu YOU
    2006, 27(6):  10-15.  doi:1000-436X(2006)06-0010-06
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    A ratio-adjustable time-frequency training sequence was proposed. The coarse carrier frequency offset (CFO) estimation was accomplished with the aid of the training sequence in frequency domain and a predefined lookup table,while the fine one was obtained by the aid of the training sequence in time domain. Simulation results show that the per-formance of the proposed method is better than Lei's method with almost the same overhead. However,its computational complexity is much lower than Lei's.

    New approach for 2-D spectrum estimation—— parameter weight method
    Zheng BAO,Yong-liang WANG
    2006, 27(6):  16-20.  doi:1000-436X(2006)06-0016-05
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    A new approach of 2-D MUSIC algorithm was proposed. Using the eigenvector and the eigenvalue of the co-variance matrix simultaneously,the method was composed of two one-dimension searching and avoided the costly 2-D searching. The pairings of the estimated parameters were automatically determined and the estimation precision was high. It was proved that the algorithm was valid even in the case that one of two parameters was same. Simulation results are presented to demonstrate the performance of the proposed method.

    Research on fault-recovery model and scheme in dual-system redundancy router
    Meng JI,Shao-hua YU,Yi-chun ZHAN
    2006, 27(6):  21-28.  doi:1000-436X(2006)06-0021-08
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    In order to improve the availability of routers,systematically presented possible implementation approaches on high-availability routers and classified them into three catalogs: protocol extension,state synchronization and data dupli-cation.It modeled and analyzed these fault-recovery schemes in continuous-time Markov chains (CTMC). Based on theo-retical results,it proposed a novel adaptive fault-recovery method (AFM) to dynamically select protection and restoration methods. It is illustrated that AFM could effectively improve the availability and is scalable. It has been implemented on a 128Gbit/s high-performance router.

    Performance analysis of generalized processor sharing based on fractal leaky bucket regulators
    Zhi-gang CHEN,Lian-ming ZHANG,Xiao-heng DENG,Ming ZHAO
    2006, 27(6):  29-35.  doi:1000-436X(2006)06-0029-07
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    In order to analyze the effect of self-similar traffic on the generalized processor sharing (GPS),the relationship was explored between the performance of a GPS system and the parameter of self-similar traffic. The self-similar traffic getting into the GPS system was regulated using the envelope curve of the fractal leaky bucket (FLB). The upper bounds on queue length and delay of the GPS system with self-similar traffic input was derived. Numerical simulations demonstrate that the performance model of a GPS system based on fractal leaky bucket regulators is suited for the self-similar traffic.

    Researches on the problem of link disjoint paths pair with QoS constraints
    Pin ZHANG,Jian-wu ZHANG,Le-min LI,Sheng ,WANG
    2006, 27(6):  36-42.  doi:1000-436X(2006)06-0036-07
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    The problem of link disjoint paths pair with QoS constraints was discussed. Two routing models about link dis-joint optimal paths pair with QoS constraints were constructed. First it proved that the problem of link disjoint paths pair in the undirected graph without end to end QoS constraints counld be converted to the correspond problem in its link split graph,while the problem with end to end QoS constraints counld not be converted. Then it's proved that both of these questions are NP complete. Finally the approximation algorithms is given and simulation on them is made.

    Blind video watermarking algorithm based on correlations between neighboring frames
    Qi GAO,Ren-hou LI,Lian-shan LIU
    2006, 27(6):  43-48.  doi:1000-436X(2006)06-0043-06
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    A blind video watermarking method was proposed,in which the watermark composed of symbol part and in-formation part was embedded into the original video frames. After some video frames hiding the watermark were selected randomly from one segment of the video sequences,the symbol water mark was embedded into low frequency discrete cosine transform (DCT) coefficients of fixed blocks of such frames,whereas the information water mark was embedded into direct current coefficients of some other blocks selected by a cryptographic key. Repeat embedding till the whole video was watermarked. To extract the information watermark,the frames holding watermark were found out by detect-ing water the symbol mark rapidly from one video segment whose length was long enough to hold the whole watermark. Then,by using the high correlations between the watermarked frame and its neighboring frames,the pixel values of the blocks where the watermark was embedded can be well estimated. Comparing the estimated values with the current val-ues in the corresponding positions,the information watermark could be reconstructed. Experimental results show that this video watermarking method is robust against attacks such as compression,scaling,frame dropping,etc.

    Single channel multicomponents separating
    AIQuan-wei C,Ping WEI,Xian-ci XIAO
    2006, 27(6):  49-56.  doi:1000-436X(2006)06-0049-08
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    A energy separation method to separate the single channel multiple signal components was proposed. This method separated two or three components based on instantaneous frequency and amplitude estimation of each compo-nent using energy operator. Simulation results show that the method can achieve less than 7.5% separation mean absolute error for three overlapped signal components when SNR is above 25dB.

    Low complexity MIMO-OFDM channel estimation based on space time block training sequence
    Liang DONG,Xiu-ying CAO,Guang-guo BI
    2006, 27(6):  57-63.  doi:1000-436X(2006)06-0057-07
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    In order to improve the performance of MIMO-OFDM channel estimation,the connection between MMSE channel estimator and subspace projecting was analyzed in the context of space time block training sequence firstly. Then the LS channel estimator obtained simply by space time block training sequence was projected to the signal subspace to get an estimator that was efficient but of low complexity. To further improve the estimation performance,the multipath delay was estimated by FFT,and then a more accurate channel response signal space was obtained,so the performance of subspace projecting was also improved. The efficiency of the algorithms presented is proved by computer simulations.

    Performance simulation and analysis of SIP-based call setup over AODV-routed MANET
    Xiao-yan ZHANG,Xiao-feng DU,Xiang-hua ZHU
    2006, 27(6):  64-71.  doi:1000-436X(2006)06-0064-08
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    In order to use SIP in MANET,a new SIP call setup mechanism was proposed which could finish the route discovery and SIP call setup simultaneously through extending the AODV routing protocol. Simulation results and per-formance analysis show that the new proposed mechanism can maintain lower call setup delay and higher successful call setup ratio when compared to the SIP MANET running on the normal AODV.

    Technical Report
    Novel ASON routing implementation
    Jian LI,Ai-ping YANG,Wan-yi GU,Jie ZHANG
    2006, 27(6):  72-80.  doi:1000-436X(2006)06-0072-09
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    An OSPF-based ASON routing implementation was proposed. In the implementation a wavelength LSA and network node LSA were extended to distribute wavelength and topology information. The topology was discovered automatically and routing messages were delivered reliably. In addition,the RWA interface was designed to introduce RWA algorithms easily. The simulation results show that the routing protocol implementation could converge rapidly and could be extended easily at low protocol overhead. The routing information flooding trigger strategies and the feasibility of flooding wavelength information throughout the network are also analyzed.

    Design and simulation of a tunable frequency OTA -C Chebyshev filter
    Jin-guang JIANG,Yao-nan WANG
    2006, 27(6):  81-87.  doi:1000-436X(2006)06-0081-06
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    A new transconductor operational amplifier(OTA) using active resistor of source degeneration was presented. The method was developed through acting differential pair degenerated by two MOSFET operating in the triode region as active resistor in its input stage,the circuit was designed in working in stable quiescent operating point with folded cas-cade output stage using voltage common-mode feedback(CMFB) circuit. As an tunable cutoff frequency fourth order Chebyshev lowpass filter,an accurately tunable Gmof OTA was used,which employed switching capacitor technique to tune Gmvalue. Simulated results show that the practical frequency response of the filter is very near to that of idealized prototype by applying 2-poly 4-metal 3.3V power supply 0.35μm CMOS technology spice model.

    Large scale network worm detection using automatic signature extraction
    Ping WANG,Bin-xing FANG,Xiao-chun YUN
    2006, 27(6):  87-93.  doi:1000-436X(2006)06-0087-07
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    Worms had done serious harm to the computer networks due to their propagating speeds. The research was necessary to detect worms quickly and automatically. In large scale networks,flux based anomaly found module was used to screen out anomalous network data set,and automatic signature extraction was processed in succession,then its signa-ture was updated to the signature database of the signature based detection module,thus,the approach to detect unknown worms was realized. Novel epidemic can be found effectively,and the whole system is the fundament of worm automatic defense.

    Research on formal security policy model specification and its formal analysis
    Li-ping LI,Si-han1 QING,Zhou-yi ZHOU,EJian-bo H,ENHong-zi W
    2006, 27(6):  94-101.  doi:1000-436X(2006)06-0094-08
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    Formal method is one of the kernel technologies of developing high security level computer system. But by current formal development method,assurance of security policy model correctness cannot be provided directly using machine proof which is stricter than manual proof,correspondence between security policy model and security functional specification is also hard to achieve. To solve these problems,a new and effective method was proposed for specification constructing and proving by extending the specification technique of security functional specification into the specifica-tion of security policy model. Also,BLP model was specified and analyzed as an example.

    Turbo detection-decoding method for bit-interleavered random layered space-time codes
    Xiao-we LI,Fang-jiong CHEN,Gang WEI
    2006, 27(6):  102-107.  doi:1000-436X(2006)06-0102-06
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    Based on one kind of layered space-time code which used bit-interleavered and random-layered model,a joint detection-decoding method based on the Turbo principle was proposed. The new method used soft-interference canceller and SISO decoder and improved the exchange of soft information between them. By iterative procession it improved the performance of the whole system. The potential practice capability is proved by simulation results and computational complexity analysis.

    Short essay
    Intrusion detection method based on machine learning
    Xin-guang TIAN,Li-zhi GAO,Er-yang ZHANG
    2006, 27(6):  108-114.  doi:1000-436X(2006)06-0108-07
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    A new intrusion detection method was presented based on machine learning for intrusion detection systems using shell commands as audit data. In the method,multiple dictionaries of shell command sequences of different lengths were constructed to represent the normal behavior profile of a network user. During the detection stage,the similarities between the command sequences generated by the monitored user and the sequence dictionaries were calculated. These similarities were then smoothed with sliding windows,and the smoothed similarities were used to determine whether the monitored user's behaviors were normal or anomalous. The results of the experience show the method can achieve higher detection accuracy and shorter detection time than the instance-based method presented by Lane T.

    New data fusion model of intrusion detection—— IDSFP
    Jun-feng TIAN,Wei-dong ZHAO,Rui-zhong DU,Hong-yun CAI
    2006, 27(6):  115-120.  doi:1000-436X(2006)06-0115-06
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    Based on multi-sensor data fusion technology,a new intrusion detection data fusion model-IDSFP was pre-sented. The model was characterized by correlating and merging alerts of different types of IDS,generating the measures of the security situation,thus constituting the evidence. Current security situation of network was evaluated by applying the D-S evidence theory,and various IDS of network were adjusted dynamically to strengthen the detection of the data which relates to the attack attempt. Consequently,the false positive rate and the false negative rate are effectively reduced,and the detection efficiency of IDS is accordingly improved.

    Academic communication
    Performance analysis of the network communication based on AMR speech coding by using NS
    Long-tao JIA,Chang-chun BAO
    2006, 27(6):  121-125.  doi:1000-436X(2006)06-0121-05
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    Most of the VoIP systems were based on the speech codec with a fixed rate,which maked packet-loss serious,especially for continuous packet-loss. The degradation for the speech quality would be caused by the kind of packet-loss. A network communication system for preventing packet-loss was given. The performance of the system was analyzed by using advanced NS. The simulation results show that the proposed system outperforms traditional IP system over the packet-loss,average delay and subjective listening quality.

    Medium access control of multimedia CDMA systems with effective spectral bandwidth distribution
    ANSu PAN,Guang-zeng FENG
    2006, 27(6):  126-133.  doi:1000-436X(2006)06-0126-08
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    A medium access control (MAC) protocol with effective spectral bandwidth distribution was proposed for the CDMA network carrying multi-service traffics. Based on the “BER limited” characteristics of the CDMA system,the protocol maps the diverse BER requirements of multimedia services into the effective spectral bandwidth. The ef-fective bandwidth was dynamically distributed to different services according to the traffic of the system. The simu-lation results show that the performance of the proposed system in terms of throughput is better than that of the exist-ing systems.

    Sort of data driven frequency-domain echo-cancellation algorithm
    Hai-jun ZHAO,Meng-tian CUI,Ming-dong LI
    2006, 27(6):  134-140.  doi:1000-436X(2006)06-0134-07
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    Trough the analysis to the data driven frequency-domain echo canceller for a multicarrier modulation system,a sort of data driven frequency-domain echo-cancellation algorithm was raised which was realized and eliminates the in-teraction in interchannel interference and intersymbol interference occuring in echo-channel . At the same time,the probability of ICI and IBI occuring in echo signal was discussed. Simulation experiment demonstrates that the satisfied echo attenuation is achieved and the computational complexity is greatly reduced by the algorithm.

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
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