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25 September 2009, Volume 30 Issue 9

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academic paper

BIS: an RFID anti-collision algorithm minimizing the cost of empty slots

Zhong-xiang WANG,Jun-yu WANG,Dan LIU,Hao MIN

2009, 30(9):  1-6.  doi:1000-436X(2009)09-0001-06

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A novel ALOHA-based medium access control (MAC) protocol, BIS, was proposed, in which the time consumption of the empty slots had been largely reduced through empty slot scanning and dynamic frame size adjustment. According to the simulation results, the system efficiency and identification speed of BIS algorithm are efficiently improved, compared to those of the normal ALOHA-based algorithms and tree-based algorithms.

Database anomaly detection model based on mining object-condition association rules

Hua DAI,Xiao-lin QIN,Liang LIU,Chuan-jie BAI

2009, 30(9):  7-14.  doi:1000-436X(2009)09-0007-08

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A database anomaly detection model based on mining object-condition association rules (OCAR) was proposed. Through analyzing and formalizing the only maximum conditional expression of SQL statements with WHERE clause, the object-condition association rule sets (OCARS) are mined, which represent normal user patterns. And the OCARS are used in anomaly detection. Additionally, OCARS mining algorithm and anomaly detection algorithm were given, and they could be easily used in anomaly transaction detection mechanism. In the end, the experiments about detecting SQL injection were given, and the performance and application were also analyzed.

Adaptive area location algorithm combining with packet lost rate and RSSI in wireless sensor networks

Fang-min LI,Ping HAN,Ting LUO

2009, 30(9):  15-23.  doi:1000-436X(2009)09-0015-09

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First, the shortcoming of existing location algorithm based on RSSI(received signal strength indication) in WSN(wireless sensor network) was analyzed. Then, supported by plenty of experimental data in different time and space, the distance evaluation model combining with packet lost rate and RSSI which aim at real environment and location algo-rithm based on this model was provided. It was regarded as a new kind of exploration for research of wireless location. Location experiments were used to evaluate the capability of this algorithm, which proves that WSN nodes running this algorithm can normally work and precision and stability are upper.

Authentication-based double images fractal watermarking model of vector maps

Jian-guo SUN,Chao-guang MEN,Chun-guang MA,Cheng-ming LI

2009, 30(9):  24-28.  doi:1000-436X(2009)09-0024-05

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To realize the invasion identification and copyright authentication, a novel digital watermarking model for vec-tor maps based on authentication was introduced. A double images fractal coding technology was proposed for the com-pound images, namely, the map owner's fingerprint was taken as the domain blocks and the vector map was taken as range blocks. The control parameters of fractal similarity computation were defined as watermarking, which could be embedded into the properties file of the map. Experiments and analysis show that, besides providing services of copyright protection, the model improves the robustness and the owners' authentication probability.

Trusted and anonymous authentication scheme for wireless networks

Li YANG,Jian-feng MA,Jian-ming ZHU

2009, 30(9):  29-35.  doi:1000-436X(2009)09-0029-07

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A trusted and anonymous wireless authentication protocol was proposed by using of temporary identities and one time secret keys, both user identity and platform were authenticated under the proposed protocol. It has demonstrated that the proposed scheme is security and reliability, it can provide identity anonymity and platform anonymity, with do-main separation property and key agreement process fairness, computation costs and turns of message exchange meet the demand for wireless IP networks security.

Research of channel quantization and feedback strategies based on multiuser diversity MIMO-OFDM systems

Xue-jun LIANG,Guang-xi ZHU,Gang SU,De-sheng WANG

2009, 30(9):  36-42.  doi:1000-436X(2009)09-0036-07

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Firstly, a quantization method was proposed by quantized value indicating the modulation level instead of the full values of channel quality information(CQI) and the achievable average spectrum efficiency showed no loss compared with perfect case. Secondly, employment of the integrated design that combined with opportunistic, best, and hybrid feedback scheme was considered and the close-form expression of average spectrum efficiency was deduced in various case. Finally, the calculation of optimal feedback parameters was confirmed from two aspects of feedback channel capac-ity and capacity relative loss. Extensive simulations were presented to evaluate these proposed strategies. The results match with the numeral analysis very well. The proposed partial feedback schemes can reduce the feedback load greatly with the same system capability, only if the feedback parameters be chosen properly. Wherein, the hybrid feedback com-bined with quantization performs best and provides the instruction to design the channel feedback of practical systems.

Anomaly detection algorithm based on fractal characteristics of large-scale network traffic

Xiao-dong XU,Shi-rui ZHU,Ya-min SUN

2009, 30(9):  43-53.  doi:1000-436X(2009)09-0043-11

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Based on the fractal structure of the large-scale network traffic aggregation, anomalies were analyzed qualitatively and quantitatively from perspective of the global and local scaling exponents. Multi-fractal singular spectrum and Lipschitz regularity distribution were used to analyze the fractal parameters of abnormal flow, trying to identify the rela-tionship between the changes of these parameters and the emergence of anomalies. Experimental results show that the emergence of anomalies has obvious signs on the singular spectrum and Lipschitz regularity distribution. Using this feature, a new multi-fractal-based anomaly detection algorithm and a new detection framework were constructed. On the DARPA/Lincoln laboratory intrusion detection evaluation data set 1999, this algorithm's detection rate is high at low false alarm rate, which is better than EMERALD.

Perfect contrast visual cryptography scheme

Yan-yan HAN,Wen-cai HE,Yu-pu HU

2009, 30(9):  54-59.  doi:1000-436X(2009)09-0054-06

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A perfect contrast visual cryptography scheme with the best contrast based on both the perfect black visual cryptography scheme (PBVCS) and the non-perfect black visual cryptography scheme (NPBVCS) was proposed. The proposed scheme applied simple Boolean operations to keep the consistency between the reconstructed image and the original secret image without pixel expansion and was easy to run.

Soft value flipping decoding algorithm for LDPC codes based on adjoint vectors sum

Jian-quan LIU,You-yun XU,Yue-ming CAI

2009, 30(9):  60-68.  doi:1000-436X(2009)09-0060-09

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By analyzing the soft value distribution while belief propagation defeated, a soft value flipping decoding algorithm based on adjoint vectors sum was presented. With translating the error times of check equation which obtained by adjoint vectors sum into error bits distribution parameter and flipping some bit nodes soft value only once at certain iteration by a selection regulation, the frame error rate of the proposed algorithm for LDPC codes which have much more correlative rows can be reduced to a larger extent without complexity increase nearly (only O(N)).

Wireless broadcasting retransmission approach based on network coding

Xiao XIAO,Wei-ping WANG,Lu-ming YANG,Shuai ZHANG

2009, 30(9):  69-75.  doi:1000-436X(2009)09-0069-07

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A novel retransmission approach in wireless broadcasting based on network coding (NCWBR) was presented, the key point of which was to combine different lost packets with network coding to achieve high efficient retransmission. Theoretical analysis reveals that the approach can ensure the solvability in the receiver nodes, and has better retransmission performance. Simulation results indicate that, comparing with existing approach, NWCBR can effectively reduce the average number of transmissions and improve the transmission efficiency.

EBS-based efficient and secure group key management in wireless sensor networks

Wei WANG,Wen-hong ZHAO,Feng-hua LI,Jian-feng MA

2009, 30(9):  76-82.  doi:1000-436X(2009)09-0076-07

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To achieve the secure group communication in wireless sensor networks (WSN), a EBS-based group key management scheme was presented. First, the network topology was simplified by combining the chain-clusters and the star-clusters. Next, to prevent the adversary uncover all the administrative keys by a few colluding sensors, the number of sensors needed to capture WSN was increased. Then, the sensors of key combinations distribution were sorted through a coloring algorithm. Based on all these operations, the presented scheme distributed the administrative keys based on the hamming distance and EBS. Furthermore, the approaches handling the join event and leave event were described. Two experiments were performed to study the potential for collusions and the influence of size of compromised nodes on the effectiveness against collusions. Simulation results demonstrate that the presented scheme boosts the WSN' resilience to attacks. The performance evaluation on join event and leave event shows that the number of key-updating messages and storage of sensors in the proposed scheme are fewer than those of SHELL.

Secure distributed signcryption scheme based on vector space

Jia LIU,NGYi ZHUA,Jian-dong WANG

2009, 30(9):  83-88.  doi:1000-436X(2009)09-0083-06

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A kind of new distributed signcryption protocol was proposed based on the ideal vector space secret sharing scheme and the modified signcryption scheme of Zheng^[1]. Without the involvement of a trusted key distribution center, this protocol could gain its ends of both threshold signature and threshold encryption simultaneously, however, its cost was equal to threshold signature only. Furthermore, based on the discrete logarithm, properties were verified and structured, the legitimacy of the participators could be confirmed during the processes of the keys generation, distributed signcryption and distributed unsigncryption, which prevented the participators cheating.

Method for assisted-GPS positioning based on ambiguity resolution in weak signal environment

Cheng SONG,Fei-xue WANG,Zhao-wen ZHUANG

2009, 30(9):  89-94.  doi:1000-436X(2009)09-0089-06

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An assisted-GPS positioning algorithm was proposed. Based on this algorithm, the receiver needn't accomplish the bit synchronization, frame synchronization and navigation data demodulation, which were usually necessary for the conventional GPS receiver, it could implement the positioning solution only by the measurement of pseudo-code phase and the assistance data (including ephemeris information and satellite clock corrections etc.). Compared with the conventional GPS positioning algorithm, the proposed algorithm increases the ambiguity of the signal transmission time as an unknown parameter for the pseudorange equation. When the initial errors of approximate location and receiver's clock bias were subjected to a constraint domain, the ambiguity of the signal transmission time could be eliminated. Then, the iteratively equation for this algorithm was derived, and the main steps were summarized. The simulation results show the validity of the algorithm.

Smart low power listening for wireless sensor networks

Si-quan HU,Jun-feng WANG

2009, 30(9):  95-101.  doi:1000-436X(2009)09-0095-07

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As a representative MAC for wireless sensor networks, low power listening (LPL) used a long preamble in each transmission and caused significant overhearing cost in a dense deployment. To save such cost, a new MAC proto-col- smart low power listening (SLPL) was proposed by embedding destination address and preamble index into the or-dinary preamble. Both the theoretical analysis and the deployment test show that SLPL outperforms LPL in power effi-ciency. The test also shows that SLPL saves more power than X-MAC.

Technical Report

Research on Linux network packet buffer recycling toward multi-core processor

Qi YAO,Ji-qiang LIU,Zhen HAN,Chang-xiang SHEN

2009, 30(9):  102-108.  doi:1000-436X(2009)09-0102-07

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A lock-free algorithm for Linux packet buffer recycling on multi-core processor was proposed. Through mak-ing a model of Linux network packet forwarding, the principle of Linux packet buffer recycling was analyzed, and the main reason that the mechanism wasn't extensible on multi-core processor was pointed out . It was that mutual exclusion and cache coherence operations consumed too much CPU clock tick. A new buffer recycling algorithm named MSRQ was designed and implemented. With the new algorithm, the parallel operations on the recycling queue were permitted without mutual exclusion on multi-core processor. And the new algorithm had better cache behavior than original recy-cling algorithm. The experiment result shows that the performance of Linux network packet forwarding with the new algorithm can be improved more than 67%.

Data equilibrium based energy-saving scheme in mobile wireless sensor networks

Shuai GAO,Hong-wei HUO,Hong-ke ZHANG,Si-dong ZHANG

2009, 30(9):  109-116.  doi:1000-436X(2009)09-0109-08

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Aiming at dense wireless sensor networks with a path-constrained mobile sink, an optimized partition scheme of sub-sinks' overlapping time was proposed based on data equilibrium. And a two-phase communication protocol was designed to effectively control the amount of data generated by each node through diffusion of the data equilibrium in-formation. Simulation experiments show that the proposed protocol and algorithms outperform other conventional methods in terms of data equilibrium rate, network lifetime.

Modified Cramer-Rao lower bound for symbol width estimation from a phase-shift-keying signal

Zhen-miao DENG,Yu LIU

2009, 30(9):  117-121.  doi:1000-436X(2009)09-0117-05

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The modified Cramer-Rao lower bound (MCRB) on symbol width estimation of a phase-shift-keying signal was derived. When calculating the integration of the square of dirac delta function δ (t), Parseval's theorem was used to transform the computation from time-domain to frequency-domain. Then the closed-form analytical solution of MCRB for symbol width estimation was derived when the pulse shaping function was the rectangle pulse. However when the pulse shaping function was the raised cosine (RC) pulse, the MCRB is evaluated by numerical simulation. The results show that the MCRB of rectangle pulse shape is higher than that of RC pulse with the roll-off factor to be 0.5 and the difference was about 1 dB.

Multiplierless discrete Fourier transform based on moments

Zhen-bing LIU,Jian-guo LIU,Guo-you WANG

2009, 30(9):  122-127.  doi:1000-436X(2009)09-0122-06

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A novel algorithm to perform Discrete Fourier Transform (DFT) multiplierlessly was proposed. First, by modular mapping and truncating Taylor series expansion, the DFT was expressed in the form of the product of the con-stants and discrete moments. Second, by performing appropriate bit operations and shift operations in binary system, the product could be transformed to some additions of integers. The proposed algorithm only involved integer additions and shifts because the discrete moments could be computed only by integer additions. The systolic VLSI was designed to perform the new algorithm, followed by complexity analysis. Compared with the state-of-the-art systolic structure, the proposed design was multiplierless and easier to implement with less hardware and time. The approach was also applicable to other discrete transforms.

Academic communication

Research on NS2-based optical burst switching network simulation platform

Zhi-jun ZHU,Zi-chun LE,Ran ZHU

2009, 30(9):  128-134.  doi:1000-436X(2009)09-0128-07

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An OBS network simulation platform OBS-NP (OBS-NS2-platform) based on NS-2 was presented. It ex-tended the node class and link class on the basis of NS-2, and provideed the simulation surroundings for key optical burst switching algorithms. After detailed description for the structure of the OBS-NP system, a OBS network with nine nodes was taken as an example to obtain routing results and some significant network parameters, such as the throughput, delay of the burst packets and resource utilization. Finally, the accuracy of the simulation results was discussed and analyzed.

Approach for information systems security situation evaluation using improved FAHP and Bayesian network

Yu FU,Xiao-ping WU,Qing YE

2009, 30(9):  135-140.  doi:1000-436X(2009)09-0135-06

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An approach for the information systems security situation assessment based on an improved FAHP and Bayesian network was proposed to solve the problem of obtaining the risk grade. The improved FAHP was used to quantify the factor of attack severity which was hard to scale. Simultaneously, the conditional probability matrices for all fac-tors were defined with the expert knowledge. Then a model for information security situation assessment was established by the Bayesian network inference, and the corresponding approach was presented. Finally, an illustrative instance was given to demonstrate its rationality and feasibility. Thus it may provide a new way for assessing information systems security situation.