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    25 September 2008, Volume 29 Issue 9
    academic paper
    SyncPoint based scoring method in IDS evaluation
    Wang YANG,Jian GONG,Xiong WU
    2008, 29(9):  1-9.  doi:1000-436X(2008)09-0001-09
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    Scoring the true positive rate and the false positive rate is a key component in IDS evaluation. The accuracy of the scoring method affects the effectiveness of the evaluation results. There are two kinds of scoring methods existed, one considering the false positive and the other not. But both of them aren't accurate enough and don't scale to the traffic volume increase. The characteristics required by the evaluating window was analyzed, and a SyncPoint based scoring method utilizing the features that the IDS processes the packet in a FIFO queue way was proposed. The theoretical analy-sis and the experiment show that the SyncPoint based scoring method is better than the current methods in accuracy and the scalability.

    Authorization delegation mechanism based trust level in grid computing
    Yong DENG,Jian-gang CHEN,Ru-chuan WANG,Lin ZHANG
    2008, 29(9):  10-17.  doi:1000-436X(2008)09-0010-08
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    To meet the demand of the delegation service during multi-domain authorization in grid computing, the dele-gation negotiation process is presented to realize the authorization delegation of role and permission based on the RBDM and RT model through the introduction of trust levels. The fine-grain authorization delegation policy is given. Finally, the simulation is given to prove the feasibility of the delegation model with trust level.

    New dynamic load balancing method based on roulette wheel selection and its implementation
    Yuan-ping ZOU,Hong-lin LIU
    2008, 29(9):  18-23.  doi:1000-436X(2008)09-0018-06
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    A new dynamic load balancing method based on roulette wheel selection in multi-services network was pro-posed. There were two stages in the method, static resource configuration and dynamic route selection. In the first, the optimization distribution of traffic trunk on parallel LSP was obtained by offline optimization algorithm. In the second, the LSP was selected by roulette wheel selection. The simulation results show that the method is able not only to guaran-tee QoS of the services but also balance the network load dynamically.

    H.264 rate-distortion model based joint source channel coding scheme over wireless channels
    Xue-juan GAO,Li ZHUO,Lan-sun SHEN
    2008, 29(9):  24-31.  doi:1000-436X(2008)09-0024-08
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    A new rate-distortion model of H.264 encoder was firstly set up according to the rate distortion (R-D) charac-teristics of H.264. Then, the end-to-end video transmission distortion was analyzed and based on the R-D model of the H.264 encoder and the error combat characteristics of the Turbo code, an adaptive joint source channel coding (JSCC) over wireless channel was proposed, which could optimize the rate allocation of the available network bandwidth be-tween source coding and channel coding adaptively according to the actual condition of current wireless channel, so as to improve the robustness of the video transmission. The experiment results indicate that, compared with fix choice of channel coding rate, the proposed JSCC scheme is can greatly improve the transmission robustness and achieve better reconstructed video quality at the receiver.

    Deterministic upper bounds on QoS performance about wireless ad hoc network based on network calculus
    Qing-hua LI,Zhi-gang CHEN,Lian-ming ZHANG,Feng ZENG,Xiang LI
    2008, 29(9):  32-39.  doi:1000-436X(2008)09-0032-08
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    In order to guarantee the QoS for wireless ad hoc network, the QoS deterministic upper bounds need to be ac-curately calculated. The data flow entering the node was regulated by leaky bucket, and the node provided rate-latency service for the flow. The node's backlog upper bound,the end-to-end upper delay bound and the end-to-end upper delay jitter bound had been derived for wireless ad hoc network based on the existing link throughput model using network calculus theory. For grid topology wireless ad hoc network, all simulated results for different data flows were bounded by theoretical results. These show the QoS performance upper bounds model perform well.

    Design of low power and high speed FFT/IFFT processor for UWB system
    Liang LIU,Xue-jing WANG,Fan YE,Jun-yan REN
    2008, 29(9):  40-45.  doi:1000-436X(2008)09-0040-06
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    A new 128/64-point FFT/IFFT processor used in Ultra-Wide-Band (UWB) system was presented. The proces-sor, which is based on 8×8×2 mixed radix algorithm, can deal with multiple inputs more efficiently for MIMO applica-tions. A new eight-path-feedback structure, which can provide a higher throughput and lower power dissipation, was proposed. The test chip has been fabricated using SMIC 0.13μm single-poly and eight-metal CMOS process with a core area of 1.44mm2. The throughput of this chip is up to 1Gsample/s, and the power dissipation is 39.6mW when it works at the throughput of 500Msample/s which meets the UWB standard. This chip reduces 40% of core area and saves 45% of power dissipation compared with those existing 128-point FFT processors.

    Optimal path identification to defend against DDoS attacks
    Guang JIN,Jian-gang YANG,Yuan LI,Hui-zhan ZHANG
    2008, 29(9):  46-53.  doi:1000-436X(2008)09-0046-08
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    A novel packet marking scheme, optimal path identification (OPi), was proposed to defend against DDoS at-tacks. Instead of using fixed 1 or 2 bit in previous schemes, in OPi a router deduces the traveling distance of an arrived packet by its TTL value and inserts a variable-length marking of 1~16 bit into the packet. The marking field is filled completely even the path is very short and the distinguishability is improved. OPi outperforms previous schemes, espe-cially when attacker paths adjoin user paths seriously. To obtain better performance, an OPi+TTL filtering strategy was proposed to frustrate attackers' tries with spoofed initial TTL values. Theoretical analyses and simulations with actual Internet topologies show OPi performs excellently.

    Partition detection for large scale ad hoc networks
    Jian-dong LI,Ye TIAN,Min SHENG,Yan ZHANG,Jun-liang YAO
    2008, 29(9):  54-61.  doi:1000-436X(2008)09-0054-08
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    As the failure of a critical node will directly partition a network, a theorem for critical node identification was proved, which indicates that node degree Niand elementary loop degree Miof node i are two decisive factors for the exis-tence of a critical node and shows that Ni-Mi≥2 is the necessary and sufficient condition for node i being critical. Based on the theorem, a distributed topology partition detection algorithm (distributed partition detection protocol, DPDP) was presented for large scale networks, which achieves the goal of partition detection efficiently by detecting critical nodes in a local area. Theoretic analysis and experiment results show that DPDP has the advantages of low complexity, high accuracy, low cost as well as good scalability, and is superior to other algorithms.

    Research of ZCZ array pair and its construction methods
    Jun-ping GAO,Qi LI,Ju-feng DAI,Li LIU
    2008, 29(9):  62-67.  doi:1000-436X(2008)09-0062-06
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    A new quasi-perfect discrete signal—ZCZ array pair which has good periodic correlation property and its con-struction method was proposed. Based on perfect array pair and orthogonal matrix, ZCZ array pairs set with certain vol-ume, family size and zero correlation zone can be synthesized through row or column interleaved technique when suitable shift sequences are selected. Except the binary case, the proposed technique can be applied to synthesize polyphase ZCZ array pairs set also. These ZCZ array pairs sets are feasible as multi-user signal, and extend the selectable scope of two-dimension perfect discrete signal.

    Extending locked range of digital phase-locked loop by prediction estimation of states
    Yi-bo ZHAO,Xiao-shu LUO,Dao-yang ZHANG,Jiu-chao FENG
    2008, 29(9):  68-72.  doi:1000-436X(2008)09-0068-05
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    A method to extend locked range of the positive zero crossing detection digital phase-locked loop(ZC-DPLL) was proposed. The nonlinear dynamical model of phase error of a non-controlled DPLL is firstly built, linearation predic-tion estimation of phase error in the stationary point domain is derived. Then nonlinear function of this prediction estima-tion is used to control by feedback. Locked range of the phase-locked loop is extended. Stability of fixed point of the controlled system is analyzed and the results by simulation are given. The effects not only show the proposed method is correct and effective but also it is superior to delay feedback method.

    Technical Report
    Improved speech enhancement based on spectral subtraction and auditory masking effect
    Xiao-qun ZHAO,Xiao-shan HUANG
    2008, 29(9):  73-80.  doi:1000-436X(2008)09-0073-08
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    Taking into account the masking properties of human auditory system and the uncertainty of the speech pres-ence, the novel algorithm modifies the log-spectral amplitude estimation and the speech absence probability (SAP) pa-rameter. Then, the smoothing parameters in noise estimation and prior SNR estimation are adaptively adjusted to modi-fied SAP parameter which reflects the degree of stationary of the measured signal. The change of smoothing parameters allows for automatic adaptation with various noisy environments and obtains the best trade-off. Experimental results demonstrate that the proposed algorithm has better performance of speech articulation without any perceptional musical-ity, compared to another modified spectral subtraction algorithms under the same level of noise reduction, and this supe-riority is more significant at very low SNR.

    Parallel MAC protocol based on geographical location information and power control in ad hoc networks
    Lei LEI,Zong-ze XU
    2008, 29(9):  81-90.  doi:1000-436X(2008)09-0081-10
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    The conflict interference produced by the parallel transmission of the exposed nodes was investigated, and a parallel MAC protocol based on geographical location information and power control in ad hoc networks was proposed. This protocol identified the exposed nodes by their geographical location information and introduced the power control mechanism into the parallel transmission of the exposed nodes. When the probability of the successful parallel transmis-sion was low, the protocol reduced the parallel transmissions by using the random backoff mechanism, thus avoided the interference caused by the failed parallel transmission and the energy consumption of the nodes. The simulation results show that, compared with the DCF protocol, this new protocol can improve the average throughput of the network sig-nificantly and save the average energy consumption of the nodes simultaneously, thus prolong the lifetime of the nodes and the network.

    Provable secure digital watermarking scheme
    Zheng YUAN
    2008, 29(9):  91-96.  doi:1000-436X(2008)09-0091-06
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    A novel provable security watermarking scheme was presented by adopting the digital watermarking technol-ogy, cryptology and encode method, it comprises embedding watermarks scheme and detecting watermarks scheme. The participant ID, Hash of the digital work and watermarking keys are regarded as the watermarks in the scheme, so that the watermarks can be used to authenticate lawful user and judge the ownership. The scheme has rigorously security almost against all watermarks protocol attacks. Especially, it has correct ability, as so as higher efficiency.

    Value-based adoption of MDS: an empirical investigation
    Yi ZHOU,Wei-dong MENG,Hui-ying DU,Ping-yao WU
    2008, 29(9):  97-102.  doi:1000-436X(2008)09-0097-06
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    The influence factors of customers′ behavioral intention, and constructs the regression model for the influence factors of customers behavioral intention of mobile data services(VAMDS) was analyzed. China mobile users of ease-own, GoTone and M-zone are chosen as our random surveys in Beijing, Nanjing and Chongqing. That the top three most important factors of customers behavioral intention of MDS are price, usefulness and social influence, and the security for customers' behavioral intention validated by overseas scholars isn't supported in the main MDS in China now.

    Quasi-cyclic extension based on PEG algorithm for construction of LDPC codes
    Jing LEI,Jian-hui WANG,Chao-jing TANG
    2008, 29(9):  103-110.  doi:1000-436X(2008)09-0103-08
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    Several important relations between the cycle structure on the Tanner graph and the parity-check matrix H of LDPC codes were proved. A new algorithm for constructing LDPC codes was proposed that introduced quasi-cyclic ex-tension method to PEG algorithm. After a basic matrix was constructed with PEG algorithm, circulant permutation ma-trices would replace the “1”s in the basic matrix. The new method could eliminate effectively the short cycles in the basic matrix without changing the degree distribution fraction of the basic matrix. Simulations show that the quasi-cyclic extended codes based on PEG algorithm have as good error correcting performance as the LDPC codes generated by PEG algorithm in the same conditions of code length ,rate, degree distribution and decoding algorithm. The conclusion of contrastive analysis is that well-chosen cycle structures can improve the decoding performance obviously under the given degree distribution. The proposed algorithm can offer a good performance and low encoding complexity synchronously by taking advantage of the quasi-cyclic code's characteristic that its parity-check matrix H has less superposition within the cycles.

    Short essay
    Study on RF module in UHF OFDM node for mobile multimedia sensor network
    Rui-fan PANG,Jian JIANG,Ying-guan WANG,Hong-jun ZHANG,Hai-tao LIU
    2008, 29(9):  111-115.  doi:1000-436X(2008)09-0111-05
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    A design of radio frequency (RF) module in ultra high frequency (UHF) orthogonal frequency division multi-plexing (OFDM) node for mobile multimedia sensor network was presented. It adopts direct frequency conversion and power back-off technologies, supports high speed multiplex data transmission in time division multiple access (TDMA) mobile network, and has the ability of high linearity, high sensitivity, wide dynamic range and high out-of-band suppres-sion. It can be applied to very important person (VIP) motorcade video wireless monitoring system, public security emergency command system, and battlefield surveillance system, etc.

    Access control model and its application for collaborative information systems
    Feng-hua LI,Wei WANG,Jian-feng MA,Hong-yue LIU
    2008, 29(9):  116-123.  doi:1000-436X(2008)09-0116-08
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    The authorization decision on resources is the major problem in collaborative information systems. Firstly, the term “action” was defined based on roles, temporal states and environmental states, and the action-based access control (ABAC) model was presented. Then, the access control mechanism based on ABAC for collaborative information sys-tems was introduced. The security association was defined and its producing procedure was proposed, which contains security properties such as user request, user identity, password, role, temporal state, environmental state and lifetime. Finally, to exchange the security properties among user, action server and resources management server, a secure authen-tication protocol was proposed, and its security was proven under the universally composable model.

    Academic communication
    Push based buffer setting strategy for high density linecard of small buffer size
    Yu-feng LI,Han QIU,Ju-long LAN,Bin-qiang WANG
    2008, 29(9):  124-133.  doi:1000-436X(2008)09-0124-10
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    Much of the previous work on buffer design of router linecard mainly focus on how to implement large and fast packet buffers, however, lots of recent theories suggest that the optimal buffer size would no longer be a large one as expected, and a small buffer should be sufficient. A push based buffer setting strategy for high density linecard of small buffer size was presented, and a buffer-revenue function was introduced to give an evaluation on using efficiency of the small buffer. It is proved that the strategy can completely eliminate the HOL(header of line) blocking problem and the back-pressure mechanism of the existing strategies, moreover, the strategy can also get a better revenue when the buffer-revenue function is used to give an evaluation.

    Security on a cryptographic model based on chaos
    Jun WEI,Xiao-feng LIAO,Ji-yun YANG
    2008, 29(9):  134-144.  doi:1000-436X(2008)09-0134-07
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    The application of chaos in cryptography has attracted much attention, however, most of them were cracked soon after publications. To find why they are so weak under the attack to their chaotic signal streams, some chaotic cryptosystems were investigated. A mathematical model was then derived from these cryptosystems. Attack and corre-sponding improvement were deployed based on the model. The research is validated with a cryptanalysis on a chaotic en-cryption scheme presented by LI S J in Physics Letters A.

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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