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25 August 2008, Volume 29 Issue 8

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Academic paper

Implementation of the optimal cooperative relay selection based on cross-layer mechanism

Yu-long ZOU,Bao-yu ZHENG,Jing-wu CUI,Chao CHEN

2008, 29(8):  1-10.  doi:1000-436X(2008)08-0001-10

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Two optimal cooperative relay selection criteria were proposed based on the A&F (amplify and forward) and D&F (decode and forward) strategies,respectively,by deriving the SER (symbol error rate) of the cooperative transmission system,and a distributed relay selection protocol at MAC layer was further presented to implement the optimal relay selection.Meanwhile,the cooperative diversity schemes at PHY layer was presented along with its performance analysis over Rayleigh fading channels,obtaining the closed-form BER (bit error rate) expressions.Furthermore,computer simulations were conducted to show the BER performances of various cooperative relay selection criteria and cooperative transmission schemes,conforming that the proposed cooperative relay selection criteria outperform the traditional relay selection rules and the proposed transmission schemes could achieve the diversity gain with the BER decreased.

Research on TDoA-based secure localization for wireless sensor networks

Hong-long CHEN,Hong-bin LI,Zhi WANG

2008, 29(8):  11-22.  doi:1000-436X(2008)08-0011-11

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Basic wormhole attack and accordance wormhole attack problems were analyzed,based on which proposed an attack detection scheme.The lower bound of the detection probability stemming from this scheme was presented theoretically.Simulation results demonstrate that the proposed scheme achieves better performance than most existing approaches under the same network parameters.

Collaborative P2P streaming dissemination strategy for random seek support

Chang-qiao XU,Zhi-mei WU,Kai-hui LI,Yuan-hai ZHANG

2008, 29(8):  23-30.  doi:1000-436X(2008)08-0022-08

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A multimedia streaming dissemination strategy called CPSD (collaborative P2P streaming dissemination) was proposed in P2P network.In CPSD,video segments were prefetched and stored in peers along a balanced binary tree in distributable manner,which assisted locating a given playing position quickly during streaming playback.Based on the buffer overlapping mechanism,an unstructured network was constructed as the routine network for video dissemination.A novel multimedia prefetching algorithm and neighborhood nodes search algorithm were proposed correspondingly,the nodes failure recovery scheme and collaboration procedure for random seek support were discussed in detail.The simulation results show that CPSD enables playing back videos more smoothly in the random seek and dynamic network conditions compared with other systems.

Pilot-based carrier frequency offset estimation in MC-DS-CDMA system

Li-cheng LIU,Xian-hua DAI

2008, 29(8):  31-38.  doi:1000-436X(2008)08-0030-08

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A pilot-based multiple carrier frequency offset (CFO) estimation algorithm was proposed for the uplink of multicarrier DS-CDMA (MC-DS-CDMA) system.By exploiting the low-pass property of the CFO vector,a novel comb pilot transmission scheme was designed to approximately acquire the single user signals on the pilot subcarriers at the receiver end.With the phase-angle averaging method to deal with the phase-angle of the quotient of two neighboring sample signals on the pilot subcarriers,the good result of the multiple CFO estimation was achieved.Further,the discrete Fourier transform (DFT) was employed and consequently improved the algorithm’s robustness to the interference.The simulation results show that with small number of users (＜3) and high signal to noise ratio (SNR) (＞15dB),the phase-angle averaging method may obtain the mean of CFO estimation error below 1%; while under the conditions of multiple users and low SNR(＜5dB),the DFT method can still reach the mean of CFO estimation error equal to 0.1% for the normalized CFO scale (?0.5,0.5).The proposed algorithm is applicable for the fine CFO estimation through the frequency selective fading slow time-vary channels.

Hierarchical computation approach to global trust values for P2P environments

Jing-cheng OUYANG,Ya-ping LIN,Si-wang ZHOU,Jian-ming ZHANG,Ye-qing YI

2008, 29(8):  39-46.  doi:100-436X(2008)08-0038-08

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A hierarchical computation global trust model,which did not depend on any set of high trust nodes,was proposed for P2P environments.A distributed implementation of the model was presented.By subtractive clustering,a large network was logically divided into some small networks which were reorganized into an overlay network with two layers in the model.Iterations were concurrently done in these small networks.Global trust values of nodes were gained by aggregating these iteration results according to the order of layers after iterations had converged.Theoretic analyses and simulation results show that,comparing to current global trust models,the proposed model can reduce amount of calculations and overheads of communication as well as converges more quickly.

Covert channel mitigation method for secure real-time database using capacity metric

Hai-tao ZENG,Yong-ji WANG,Li RUAN,Wei ZU,Jia-yong CAI

2008, 29(8):  47-57.  doi:1000-436X(2008)08-0046-11

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A capacity using covert channel mitigation method (CUCCMM) was proposed.This method uses capacity as metric for channel danger measure according to trusted computer system evaluation criteria (TCSEC) and multiple probabilities based protocol selection policy (MPBPSP) to guide the application of secure concurrency control protocol.The algorithms of channel’s capacity measure and policy’s parameter computing are also presented.Experimental results show that CUCCMM implements the restriction criterion on channel’s capacity effectively and accurately,and the MPBPSP significantly decreases the influence of restriction operation on real-time performance.

Cryptanalysis and improvement of two ring signature schemes provably secure in standard model

Hua-qun WANG,Hong YU,Xian-qiang LV,Fu-tai ZHANG,Yan-fei SUN

2008, 29(8):  58-63.  doi:1000-436X(2008)08-0057-06

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The security of the two ring signature schemes proposed by Au(2006) and Chow(2006) was analyzed,and it’s found that both the ring signature schemes were susceptible to multiple-known-signature existential forgery or group-changing attack.To guard against the two attacks,the two ring signature schemes were improved,which can make the improved schemes were still secure even in the stronger security model.

Numerical analysis of Raman amplifier based on triangular photonic crystal fiber

Tao SHANG,Feng LI,Zeng-ji LIU

2008, 29(8):  64-69.  doi:1000-436X(2008)08-0063-06

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A numerical design on the triangular PCF-based backward multi-pump Raman amplifier was presented.It is demonstrated that high flat Raman gain can be reached based on PCF.Influences of different geometric parameters and germanium concentrations on the Raman net gain,amplified spontaneous emission (ASE) noise and double Rayleigh backscattering (DRBS) of the signal have been analyzed.Meantime,comparison with multi-pump gain-flat Raman amplifiers based on standard single mode fiber was also carried out.The results showed that PCF is an appropriate candidate for high gains Raman amplifiers.The results also indicate that for optimizing crystal fiber Raman amplifier,there is tradeoff between the geometric parameter and germanium-doped concentration of triangular PCF.

Research on routing in ad hoc networks using directional antennas

Quan YU,Ke-jun WU

2008, 29(8):  70-77.  doi:1000-436X(2008)08-0069-08

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To decrease overload and cost of routing discovery through directional antennas and effectively make use of high spatial reuse and high transmission ability of it,a routing protocol,called DLAODV (using directional antennas and location-aided ad hoc on-demand vector routing),was proposed.In DLAODV,location information was got on demand.During route discovery,flooding,limited flooding in expected zone,routing contraction,location correct-based greedy forward strategy and method to resolve partition of the network were combined to improve the performance.In addition,a novel method for routing maintenance was illustrated.Simulation results show that,DLAODV can achieve better performance in packet delivery ratio and delay,and routing overhead is significantly decreased.

Technical Report

Research and implement on one-hop transmission technology in network coding based-mobile IP

Yi-fei LU,Jun TAO,Cheng SHEN

2008, 29(8):  78-88.  doi:1000-436X(2008)08-0077-10

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The concept of the network coding was introduced in the one-hop transmission between base station and the mobile nodes.Then the concept of the coding group was proposed,and transmission model was also described based on coding group.Furthermore,network coding and nest network coding transmission methods under this model were introduced,and then through the analysis of the methods,the coding group transmission control algorithm and the improved algorithms was proposed.At last,after the simulation,the coding group transmission can do improve the wireless transmission correct rate comparing to the traditional unicast transmission,at the same time it can decrease the retransmission which would lead to improvement of mobile IP performance.

Hybrid particle swarm optimization algorithm for cost minimization in service-workflows with due dates

Xiao-dong ZHANG,Xiao-ping LI,Qian WANG,Ying-chun YUAN

2008, 29(8):  89-95.  doi:1000-436X(2008)08-0087-07

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The cost minimization with due dates in service-workflow systems is an intractable problem.Traditional level-based algorithms restricted the due date within a time-window and the search scope was limited.HPSO (hybrid particle swarm optimization) algorithm was proposed by adapting a PSO algorithm effective for continuous problems.The proposed algorithm introduced operators of the particle randomly disturbing extremum,the position trace back and the crossover.By extending the research scope to the entire space,HPSO could obtain the optimal solution with a higher probability.Experimental results show that the HPSO reduces the cost 12.82% on average to that of the best currently available algorithm,as well as only 6.5s for a problem with 120 activities.

DLRD:a P2P grid resource discovery mechanism for dynamic load-balance

Bao-yan SONG,Nan GAO,Xiao-guang LI,Jian-sheng XUE

2008, 29(8):  96-101.  doi:1000-436X(2008)08-0094-06

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Grid technology is an efficient way to resolve the resource sharing and cooperative work in distributed environments.The resource discovery mechanism is a key problem in grid.Some resource discovery mechanisms were introduced thoroughly at present,and proposes a dynamic load-balance resource discovery mechanism in grid——DLRD,and gives relevant algorithm.DLRD implements complete distributed dynamic resource discovery based on P2P.It can increase nodes of grid to implement balancing register and location of resource.

Single base station hybrid positioning scheme based on data fusion technique

Ling-wen ZHANG,Zhen-hui TAN,Jin-bao ZHANG

2008, 29(8):  102-106.  doi:1000-436X(2008)08-0100-05

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A novel single BS positioning scheme for TD-SCDMA systems was proposed called HPSR (hybrid positioning scheme with RSS),by which the interference caused by multilateral positioning systems is avoided.Moreover,one RSS data fusion model is established to eliminate NLOS error and improve the accuracy of positioning.A specific flowchart to be put into practice is given and simulated.The results indicate that compared with present TOA/AOA,the proposed scheme is more stable and accurate.

Research of an cascaded neural net filter applied in echo-cancellation

Hai-jun ZHAO,Meng-tian CUI,Ming-dong LI

2008, 29(8):  107-112.  doi:1000-436X(2008)08-0105-06

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In view of the echo path having both linear and non-linear attributes,and acoustic echo cancellers in today's relied mainly on the assumption of a linear echo path,a cascaded neural net filter as the filter structure in a non-linear acoustic echo canceller( AEC) was proposed.It consisted of a feedforward neural net filter,in series with a linear FIR filter.Different adaptive algorithms were used to estimate the linear and non-linear parts of the filter.The experimental results indicate that the adaptive cascaded neural net filter converges to a higher echo return loss enhancement(ERLE) than the linear adaptive FIR filter.

Overview

Survey of MAC protocol in wireless multimedia sensor networks

Rui-fang LI,Ren-fa LI,Juan LUO

2008, 29(8):  113-125.  doi:1000-436X(2008)08-0111-13

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Wireless multimedia sensor networks (WMSN),as a multimedia information acquiring and processing technology,potential applications span a wide spectrum from military to industrial,from commercial to environmental monitoring.Research on wireless multimedia sensor networks relates to many techniques,MAC protocol is one of them.The characteristics and technical challenges of MAC in WMSN was summarized,the state of the art in algorithms,protocols was surveyed from channel access policies,scheduling,error control and Multimedia packet size,open research issues are discussed in detail,the open research problems were also pointed out.Finally,the simulation tools of MAC in WSN was analyzed and compared.

Academic communication

DS-CDMA BSS system based on FastICA-TDS

Jin-dong ZHANG,Gui-he QIN,Tao CHEN,Jian JIN

2008, 29(8):  126-130.  doi:1000-436X(2008)08-0124-05

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In order to predict and improve the performance of the DS-CDMA network signal separation system,the original symbol was estimated,using the information of the original symbol and another two symbols around.The multichannel DS-CDMA model that also had been existed was improved,and a system model based on the TDS was proposed.The DS-CDMA blind source was seperated step by step,using the FastICA algorithm.The result of the experiment proves that this system can examine the user symbol more accurately and has lower miss rate.The method has been proposed is clearly better than MMSE and MF in the area of control of system energy.

Land use information extraction from QuickBird imagery based on pixel gray and texture characteristics

Shi-ping YE,Chao-xiang CHEN,Yu-zhang WEI,Xiao-can ZHANG

2008, 29(8):  131-137.  doi:1000-436X(2008)08-0129-07

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To improve the accuracy of land-use information extraction from QuickBird high-resolution satellite images,an automatic and level dividing(from buildings to water bodies then to farmlands) extraction method was proposed,which combined pixel gray values and texture features together as classification factors.CON and MCON were proved to be more suitable for land-use information extraction than other texture parameters through definition filtration and comparison among stabilities of texture formulas.A solution for selecting classification factors was presented based on standard distance.Good effects were achieved in experiments,which showed that the extraction accuracies of buildings,water bodies and farmlands reached 93%,88%,88% respectively.

Research of blind equalization algorithm based on fifth-second order normalized cumulant in complex system

Li-yi ZHANG,Yu BAI,Qiang LI,Jian-fu TENG

2008, 29(8):  138-142.  doi:1000-436X(2008)08-0136-05

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According to the symmetric-antisymmetric transform principle,a fifth-second order normalized cumulant blind equalization algorithm was proposed.The algorithm overcame the disadvantage that the channel equalization was impossible for the symmetric signal because its odd order cumulant equaled to zero.The computer simulation shows that the convergence and the steady residual error of the algorithm are better than congener algorithms and its realization is simple.