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25 April 2010, Volume 31 Issue 4

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Academic paper

Energy saving scheme based on life period division for wireless sensor networks

Chao SHA,Ru-chuan WANG,Hai-ping HUANG,Li-juan SUN

2010, 31(4):  1-7.  doi:1000-436X(2010)04-0001-07

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An energy-saving data transmission scheme based on life period division was proposed.Multi-layer cluster was constructed on the basis of energy consuming prediction and the life periods of sensor nodes were divided to ensure the balance of energy consumption.By changing node's working mode,network lifetime was further extended.Simula-tion results show that this method provides longer lifetime and better equalizes energy consumption than some other energy-efficiency network protocols.

Research and implementation of a signcryption-based security mechanism in VoIP network

Ying-you WEN,Ming LUO,Hong ZHAO

2010, 31(4):  8-15.  doi:1000-436X(2010)04-0008-08

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An efficient identity-based signcryption scheme for multiple PKG environment and corresponding signature scheme were proposed,based on these,a security mechanism for VoIP network was proposed.The mechanism over-comed some problems posed by traditional security mechanism based on PKI.Moreover,entity authentication for cross-domain and confidential transmission for message were supported in the security mechanism.Through validation and analysis it is shown that the new is compliant well with security mechanism available in the primitive networks and,does not affect its security and efficiency,and the deficiency in one-way authentication and pre-sharing key of HTTP di-gest authentication mechanism is resolved ,the deficiency in certificate-based authentication of the S/MIME protocol and SRTP not providing key agreement function are eliminated.

Key predistribution with location and time binding: novel approach against node replication attacks in wireless sensor networks

Fei FU,Wang-dong QI

2010, 31(4):  16-25.  doi:1000-436X(2010)04-0016-10

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A novel pairwise key predistribution approach called LTB (location and time binding)was proposed ,in which the key material of each node were bounded with its original deployment location and time so that each node could estab-lish pairwise keys with its neighbors only at its orig l deployment location.Since replicas were deployed at different locations other than the original,they could not be accepted by their neighbors.LTB eliminates node replication threats completely while its communications overhead is much lower than that of periodical detection approaches with O ) (n against O(pn ^3/2),in which p is the number of detection periods and n is the number of nodes in the network.

Wideband DBF phased array antenna on LEO satellite

Guang LIANG,Wen-bin GONG,Hui-jie LIU,Jin-pei YU

2010, 31(4):  26-36.  doi:1000-436X(2010)04-0026-11

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Genetic algorithm with multi-objective optimization strategy was proposed to synthesize the antenna array on LEO satellite according to the requirements of iso-flux beams coverage.Based on the rotation symmetry of beam cover-age and elements distribution,antenna elements were partitioned into groups in beam space and element space,and just one third of beam forming matrix coefficients were independent.The simplicity of DBF matrix helped reduce the number of parameters in GA and design the hardware structure DBF network.Generalized DFT filter bank,multiplex DBF computer and RF calibration in close-loop mode were adopted to design the DBF network,which can reduce the calculation by 95.5% and save the multiplier resource up to 80%.Ultimately a 61-channel phased array transmitter antenna with 16 si-multaneous beams was designed.The measurements in anechoic chamber demonstrate that the phased array antenna has good performance of iso-flux beams coverage,which validates the rationality of algorithms and project implementation.

ABE-IBS based signature-encryption method for WSN

Zheng-hua QI,Geng YANG,Xun-yi REN,Hui WANG

2010, 31(4):  37-44.  doi:1000-436X(2010)04-0037-08

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In order to improve the security and efficiency performance of wireless sensor network signature-encryption,on the basis of identity-based signature(IBS) with the bilinear pairings on elliptic curves,an attribute-based encryption combined with identity-based signature (ABE-IBS) scheme was proposed,besides,one efficient signature-encryption scheme for WSN was also discussed.Analysis and experimental results show that proposed scheme has the low complex-ity and storage requirement,and can enhance the security of wireless sensor network.

Research and implementation of one-hop transmission framework in wireless network based on network coding

Yi-fei LU,Jun TAO,Cheng SHEN,Qin XIA

2010, 31(4):  45-54.  doi:1000-436X(2010)04-0045-10

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To solve the problem of the efficient transmission in error-prone wireless network and unfairness attribute to retransmission.Inspired by the network coding,a transmission model based on coding group (TCG)was proposed.Be-cause of the different type of packets of central station,this model also could be divided into internal transmission model (LTCG) and external transmission model (ETCG).Furthermore,a transmission framework based on coding group (FTCG was introduced as to the above model.At last,through the simulation,the transmission delay and throughput of the un-icast strategy and FTCG separately were analyzed and compared.Moreover,under the condition of nodes'burst error,the influence of the unicast strategy and retransmission based FTCG was proposed and analyzed.Simulation results show that FTCG can improve the transmission efficiency and solve the sharp decrement of performance with the condition of nodes'burst error.FTCG can keep the transmission fairness of the different data.

Analysis of the effects of the amplitude-phase errors on spatial spectrum and resolving performance of the MUSIC algorithm

Ding WANG,Chao WANG,Ying WU

2010, 31(4):  55-63.  doi:1000-436X(2010)04-0055-09

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Based on the perturbation theorem of orthogonal projection matrix,the first-order statistical expression of spa-tial spectrum of the MUSIC algorithm was deduced and a quadratic equation for solving the mean signal-to-noise ra-tio(SNR) resolving threshold was derived,through which the corresponding SNR resolution threshold could be obtained.Compared to currently existing method,the first-order statistical expression of spatial spectrum only volves array ma-nifold vector and source covariance matrix instead of the eigenvalue and eigenvector of the ideal array covariance matrix,besides,the mean SNR resolving threshold is suitable in the presence of power difference of two signal sources.Numeri-cal experiments validate the correctness of theoretical analysis.

Aggregation algorithm for MPLS multicast flows based on bidirectional shared tree

Ling-zhi LI,Yan-qin ZHU,Zhe YANG

2010, 31(4):  64-71.  doi:1000-436X(2010)04-0064-08

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Scalability is the mainly problem that impedes the extensive deployment of multicast in MPLS networks.An aggregation algorithm for multicast flow based on bidirectional shared tree was proposed in order to resolve the problem.The aggregated degrees of multicast flows were computed according to the relation among nodes.The label edge routers were clustered into the sets of leaf nodes on shared trees,and tree manager server computed the topology of bidirectional shared trees.The multicast flows,whose aggregated degrees were greater than the specific threshold,were finally con-verged into the trees.The test result indicates that it can greatly reduce the occupation of MPLS labels.The processes of medium nodes are simplified and the forwarding states of routers are reduced in the algorithm.It will greatly enhance the scalability of MPLS multicast.

Study of density control algorithm based on optimization of vacant energy consumption in heterogeneous sensor networks

Lin-feng LIU,Zhi-qiang ZOU,Deng-yin ZHANG,Ru-chuan WANG

2010, 31(4):  72-79.  doi:1000-436X(2010)04-0072-08

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The scheme of gradually topology expansion was adopted and a density control algorithm DCA aiming to re-duce the vacant energy consumption was presented for heterogeneous WSN.A connected coverage set based on mini-mizing vacant energy consumption can be found by DCA,the set would be mapped into the active nodes set finally.Both theoretical analysis and experimental data suggest that DCA can achieve well-constructed topology and prolong network lifetime effectively.

Multiuser carrier frequency offset estimation for WiMAX periodic ranging based on OFDMA

Da FAN,Zhi-gang CAO,Zhi-ling YI

2010, 31(4):  80-87.  doi:1000-436X(2010)04-0080-08

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Under WiMAX OFDMA framework,two carrier-frequency offset (CFO) estimation methods for multiuser case were proposed for periodic ranging process.The theoretical results of the two methods were derived in the case of multiuser,in which the time-domain and frequency-domain correlation properties of PN code are used for extracting the desired ranging user respectively.Simulation results show that the proposed frequency-domain correlation method per-forms better than the time-domain correlation method even in the case of multiple users simultaneously existing in one ranging time-slot.And it more robust to timing offsets result from the symbol timing offset (STO) estimation error.

Technical Report

Application of weighted-type fractional Fourier transform in sampling and reconstruction

Jun SHI,Yong-gang CHI,Xue-jun SHA,Nai-tong ZHANG

2010, 31(4):  88-93.  doi:1000-436X(2010)04-0088-06

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A new sampling and reconstruction scheme based on the weighted-type fractional Fourier transform(WFRFT) was proposed for a class of signals which were nonbandlimited in the frequency domain.Based on the representation of the signal in the WFRFT domain,conditions under which exact recovery of the signal is possible were derived.Theoreti-cal analysis and simulation results show that the prop d scheme can perfectly recover signal below the sampling rate of Shannon reconstruction within the given error tolerance,and it can be implemented efficiently with the fast Fourier transform(FFT) algorithm.

Evaluating the network security by the Read_Write transition model

Zhi-yong LU,Chao FENG,Hui YU,Chao-jing TANG

2010, 31(4):  94-102.  doi:1000-436X(2010)04-0094-09

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The Read_Write transition model and correlative concepts were presented for the root directory with Read_Write privilege setting; then the model transition function was formalized by the state transition arithmetic operator?.Based on the transition model,the network security transition machine and the network security evaluation model were designed.Finally,the method's feasibility and validity were verified by analyzing some practical examples.

Overview

Survey on available bandwidth estimation in ad hoc network

Da-peng WU,Mu-qing WU,Yan ZHEN

2010, 31(4):  103-115.  doi:1000-436X(2010)04-0103-13

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With analysis of the difference between bandwidth estimation scheme in wired network and wireless network,the available bandwidth in mobile ad hoc network is defined.The factors which infect the available bandwidth including frame collision probability,backoff time and channel utilization are analyzed; meanwhile,the methods of measurement and estimation are also given;finally,the application and research trend of available bandwidth estimation is pointed out.

Short essay

Resource allocation schemes in amplify-and-forward OFDM cooperative relay systems with multimedia traffic

Shu-ping CHEN,Wen-bo WANG,Xing ZHANG,Lei FU

2010, 31(4):  116-121.  doi:1000-436X(2010)04-0116-06

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A framework of resource allocation for multimedia traffic in point-to-point OFDM (orthogonal frequency divi-sion multiplexing) cooperative relay systems was presented,an optimal adaptive power,carrier and bit allocation scheme was proposed.A sub-optimal fast-searching algorithm was proposed for practical implementation,which allocated the minimum resource to each service according to the channel conditions.Simulation results show that this scheme can meet the QoS (quality of service) requirement of the multimedia traffic while improve the spectral efficiency significantly.Moreover,performance of the sub-optimal search algorithm in terms of throughput is close to optimal scheme by 0.6bit/(s·Hz)at all SNR regime,with reduced complexity in linear polynomial level rather than O (3^N).

Channel estimation method for time-vary channel based on data fitting in OFDM system

Peng DUAN,Ming-yi HE,Ye TIAN,Min-biao XUE

2010, 31(4):  122-127.  doi:1000-436X(2010)04-0122-06

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According that the energy of periodic sequence mainly concentrates on a few frequency points,based on data fitting,a novel periodic PN sequence time-vary channel estimation method was proposed.Utilizing the auto-correlation characteristic of PN sequence,the impact of interference on pilot could be reduced in time domain; meanwhile,the num-ber of the fitting data could be increased by using the periodicity character of pilots; based on time averaging value of channel,the estimation parameter could be adjusted further,and the accuracy of channel estimation could be improved efficiently.Extensive experiment results show that the proposed algorithm is superior to other existing algorithms in per-formance of BER and MSE.It can also be applied for low signal-noise-ratio(SNR) circumstances.

New method of banknote feature extraction

Shan GAI,Peng LIU,Jia-feng LIU,Xiang-long TANG

2010, 31(4):  128-133.  doi:1000-436X(2010)04-0128-06

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Combined with the merits of Contourlet transform and fuzzy logic,a new method of banknote image feature extraction was proposed.Contourlet coefficients were extracted in different scales and directions by using Contourlet transform on the banknote image.The extracted coefficients were considered as linguistic variables.Then it calculates the firing strength on the fuzzy feature plane and normali them as feature vector.Coarse classification was conducted by banknote geometric features.Then the neural network was constructed for the recognition of banknote and the scheme of reject class was introduced.The experimental results show that this method achieves a high recognition rate and fast rec-ognition speed.The proposed method was applied in the resource constrained of embedded system.

Performance analysis of spectrum sensing using diversity technique

Qian WANG,Dian-wu YUE

2010, 31(4):  134-140.  doi:1000-436X(2010)04-0134-07

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Performance of spectrum sensing using energy detection and equal gain combining technique was investigated in the general correlated non-identical Nakagami-m fading channels.Closed-form expression of detection probability was derived,and performance improvement obtained by utilizing equal gain combining was analyzed via the asymptotical analysis.The validity of theoretical results were shown by comparing numerical results with Monte-Carlo simulations.At last,the influence of channel correlation on the detection probability was observed by Monte-Carlo simulation.