Journal on Communications

Novel mobile agent dynamic data integrity protection protocol

Peng-fei LI,Si-han QING,Heng-tai MA,Yong DENG

2007, 28(8): 1-10. doi:1000-436X(2007)08-0001-10

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Integrity characteristics of dynamic data was redefined and classified by attacker capability,and then it was analyzed how to protect truncation attack with collusion.After that,a data protection protocol of free-roaming agent was presented.The protocol used a reverse chained signature to protect the integrity of roaming path,and protected the dy-namic data integrity based on this.Specially,the protocol provided truncation resilience in collusion condition,and its secure property was proved by formal method.

Estimation scheme for parameters of wireless channel model in OFDM communication systems

Yong WANG,Jian-hua GE,Xiao-li WU

2007, 28(8): 11-15. doi:1000-436X(2007)08-0011-05

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The conventional channel estimator in OFDM system was designed to cope with the worst-case channel condi-tion,thus performance degradation can be induced due to the imperfect channel estimation.Though wiener filter based on the minimum mean-squared error (MMSE) is the optimal linear estimator,it requires the prior information of transmis-sion channel.In order to select the near optimal prestored channel interpolation filter coefficients,three channel parame-ters detecting methods including maximum multipath delay,Doppler frequency and SNR based on the time and fre-quency correlation functions of the channel,the Euclidean distance of hard-decision in pilots position respectively,were proposed.The method proposed with low complexity allows an efficient implementation for adaptive channel estimation algorithm as well as multi-user OFDM systems.

Optimal cross-layer power allocation with channel and queue state information

Wei CHEN,Zhi-gang CAO,Ping-yi FAN,K B LETAIEF

2007, 28(8): 16-23. doi:1000-436X(2007)08-0016-08

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The optimal power allocation was investigated when both channel and queue state information was taken into account.By modeling the system from a cross-layer perspective,an optimization problem was formulated on power allo-cation where the maximal power requirement of a user was determined by the number of its backlog packets.The ana-lytical solution as well as its algorithm,which refer to as water filling in cellar (WFIC),were proposed.The proposed WFIC can be reduced to traditional water-filling (TWF) method as a special case where queue state was ignored.Simula-tion results show that the proposed method can achieve lower queuing delay compared to conventional methods.

Quantitative analysis of BGP convergence and its influence on network performance

Jin-jing ZHAO,Pei-dong ZHU,Xi-cheng LU

2007, 28(8): 24-33. doi:1000-436X(2007)08-0024-10

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The relation of BGP convergence and the characteristics of the inter-domain system was analyzed.The in-ter-domain routing system is classified into three hierarchies—core layer,transmit layer and stub layer based on the power law and commercial relations of autonomous systems.The relation of network topology and convergence parame-ters were presented of all sorts of convergence events in different layers.And a new proposal has been presented to im-prove BGP convergence based on the above analysis,called Best Up,which behaved better than normal convergence mode in the experiments.

Semidefinite relaxation detector for higher-order modulated multiple-antenna systems

Yi-jin YANG,Chun-ming ZHAO,Wei XU,Peng ZHOU

2007, 28(8): 34-39. doi:1000-436X(2007)08-0034-06

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A semidefinite relaxation detector of 64-QAM signals was proposed,which is derived from rank relaxation and Lagrange bidual programming respectively.Computational complexity analyses and simulation results demonstrate the detector can make a good tradeoff between complexity and performance.

Joint frequency-angle estimation using a pseudocovariance matrix

Jian-feng GU,Ping WEI

2007, 28(8): 40-45. doi:1000-436X(2007)08-0040-06

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A computationally simple joint frequency and angle estimation method with good statistical performance was proposed.The proposed method eliminates the effect of additive noise under the assumption that the temporal-correlation length of the noise field is shorter than that of the signals,and constructs a pseudocovariance matrix by exhibiting a suffi-cient temporal correlation to obtain the frequency estimation by implementing the singular value decomposition(SVD) of it,then the angles were obtained one-by-one using 1-D searches.Finally,it is shown that the proposed method is superior in estimating the angles because of the aperture extension and offers good estimation performance of the frequencies at the low computational burden through numerical simulations.

Research on a very energy-efficient and low-delay flooding algorithm for wireless sensor network

Fang-min LI,Xin-hua LIU,Hai-lan KUANG

2007, 28(8): 46-53. doi:1000-436X(2007)08-0046-08

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A novel flooding algorithm called priority covering algorithm was proposed for wireless sensor network.In the algorithm,a method of priority covering was used for assigning different forwarding priorities to vicinity nodes so as to make the flooding packet cover the whole network rapidly; a scheme of restrained forwarding and a scheme of dynamic delay for forwarding were used for restraining the redundant flooding packets and reducing the conflicting retransmission overhead.The result of simulation shows that the algorithm is more energy-efficient and low-delay than those similar flooding algorithms proposed.

Novel cooperative power control game algorithm for cognitive radio systems

Shi-lun CHENG,Zhen YANG,Hui ZHANG

2007, 28(8): 54-60. doi:1000-436X(2007)08-0054-07

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In order to fair optimally allocate the limited cognitive radio resource,a cognitive radio system was developed based on STBC OFDM-CDMA network systems and a novel Nash bargaining solution named NBS of cooperative power control was adopted in this system,the transmitted power was dynamically adapted based on channel conditions,maxi-mal network throughput and power limits.Simulation results show that the novel algorithm can regulate their transmitter powers,fair optimally allocate radio resource.At the same power consumption,the network throughput is thereby im-proved obviously.

VLSI design of an irregular LDPC decoder in DTMB

Yun CHEN,Xiao-yang ZENG,Yi-fan LIN,Bo XIANG,Yun-song DENG

2007, 28(8): 61-66. doi:1000-436X(2007)08-0061-06

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An irregular LDPC decoder with a code length of 7 493 bits for DTMB system was implemented based on SMIC 0.13μm CMOS process.A new method to control memories was proposed,which can reuse memories for three different code rates only by increasing 5% memory usage.The throughput of the LDPC decoder is up to 150Mbit/s with the max iterative number of 15.While keeping the throughout of 50Mbit/s,its max iterative number can reach 45.The FPGA synthesis reports and the decoder layout in SMIC 0.13μm CMOS technology are given.

Particle filtering based semi-blind estimation for MIMO-OFDM time-varying channel

Yuan JING,Fu-liang YIN,Shuo ZENG

2007, 28(8): 67-75. doi:1000-436X(2007)08-0067-09

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A semi-blind channel estimation method based on the particle filtering was proposed for the MIMO-OFDM wireless communication system.By optimizing the particles distribution locally,the traditional particle filtering algorithm was modified,and a local optimized particle filtering was proposed.This local optimized particle filtering can achieve the low MSE,and improve the precision of the MIMO-OFDM time-varying channel estimation.Since this method was per-formed in frequency domain,it was not necessary to know (or estimate) the length of the channel.Compared with exist-ing approaches,the proposed method was more robust to the non-gauss distribution noise and the detection performance is nearly optimal.The simulation results show the effectiveness of the proposed method.

Video object segmentation by 2-D mesh-based motion analysis and morphological filtering

Yu-jian WANG,AOJian-po GAO,Zhen-yang WU

2007, 28(8): 76-86. doi:1000-436X(2007)08-0076-11

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A new temporal-spatial video object segmentation algorithm was proposed.This algorithm was based on 2-D mesh-based motion analysis and an improved spatial automatic segmenting strategy of morphological filtering.Firstly,higher order statistics was used for motion analysis of the 2-D mesh representation.After post-processing,relatively fine motion detection mask was quickly obtained.Then a novel watershed segmenting strategy based on alternating sequential filtering by reconstruction and adaptive threshold was applied to get the accurate boundary of the foreground object.Fi-nally,the video object was effectively extracted by fusing the temporal and spatial segmentation via region-based method.Experimental results indicate that the proposed algorithm assimilates the advantages of 2-D mesh-based algorithms and pixel-based algorithms,and achieves satisfactory subject and object performance.

Realization of 10bit,200MHz sampling frequency CMOS video D/A converter with gradient error compensation

Jiao-ying HUANG,Yi-gang HE,Hui YANG,Sheng-xue TANG,Fang SHEN

2007, 28(8): 87-91. doi:1000-436X(2007)08-0087-05

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A circuit of 10bit,200MHz sampling frequency current steering DAC with hierarchical symmetrical switching sequences was presented,which compensate the gradient error.The DAC employs segmented architecture.An integral linearity error caused by error distributes of current sources was reduced by a new switching sequence called “hierarchi-cal symmetrical switching”.The DAC was built in a video-rate adaptive equalizer IC,which was fabricated in a 0.35μm,3.3V CMOS process.The area of DAC is 1.26mm×0.78mm.When operating at 14.318 MHz (4Fsc) sampling freguency,the effective numbers of bits is 9.3.Both the integral and the differential linearity errors are less than ± 0.5LSB.

Novel wobble-defended M-MULTOPS structure and its application in detecting network abnormal traffic

Zhi-xin SUN,Yi-wei TANG,Jing GONG

2007, 28(8): 92-98. doi:1000-436X(2007)08-0092-07

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A new detection method:wobble defended M-MULTOPS (modified- multi-level tree for online packet statistics) structure was presented.Aiming at the change of network traffic in core routers,ABF (adapted bloom filter) algorithm to assemble destination addresses to the IP packets was employed.And it put forward M-MULPOTS struc-ture to analyze results of the ABF algorithm,monitoring changes of network traffic and detecting network flow ab-normity in real time.For making use of the Wobble-defended M-MULTOPS structure,the method can work steadily and exactly,even when the traffic of network is wobbling terribly by the pulse attack.And because the M-MULTOPS inherits the MULTOPS 's flexible attribution,it declined the spending of system resources at maximum.A detection system em-ploying this method has been run successfully in routers as an individual module.

Research on parallel partheno genetic algorithm based on the immune programming

Xiao-shuai XING,Bing-peng HUO

2007, 28(8): 99-104. doi:1000-436X(2007)08-0099-06

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A novel algorithm parallel partheno genetic algorithm based on the immune programming (IPPPGA) was proposed,the algorithm analogies to the concept and theory of immunity in biotic science and unifies the parallel compu-tation thought,after analyzing the advantages and disadvantages of the partheno genetic algorithm.The theory analysis and experimental results show that the algorithm not only effectively keeps population diversity,but also alleviates the undulate phenomenon in evolutionary latter stages,meanwhile increases the convergent speed and computational effi-ciency greatly.

CoMa-mSCTP:a connectivity management scheme based on mSCTP in mobile environments

Yan SHI,Shan-zhi CHEN,De-cai DONG,Yu-hong LI

2007, 28(8): 105-112. doi:1000-436X(2007)08-0105-08

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An mSCTP-based connectivity management scheme,CoMa-mSCTP,was proposed to realize the integration of bandwidth aggregation and mobility supporting at transport layer.The major path management functions were defined and the path handoff procedure was introduced.A transport path subset selection policy based on wide-sense path defini-tion was proposed.The simulations on the effect of the throughput improvement,the path subset selection policy and the mobility supporting were complemented respectively.The simulation results show that CoMa-mSCTP can realize effi-cient integration of bandwidth aggregation and mobility and the application-based path subset selection policy has ap-parent performance advantages.

Survey of wireless sensor network security techniques

Qing-qi PEI,Yu-long SHEN,Jian-feng MA

2007, 28(8): 113-122. doi:1000-436X(2007)08-0113-10

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The current situations of sensor network security,the security challenges and the security problems were pre-sented.From the aspects of key management,secure routing,authentication,intrusion detection,DoS attack,access con-trol,all the security techniques of sensor networks were introduced and discussed,and the comparisons were made to help researchers select and design the security solutions for a particular sensor network application environment.At last,the further direction of sensor network security techniques was summarized and discussed.

Research on differences set pairs and periodic complementary binary sequence pairs

Yan-guo JIA,Cheng-qian XU

2007, 28(8): 123-127. doi:1000-436X(2007)08-0123-05

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The differences set pairs were studied and some constructions of differences set pairs were put forward.A con-struction of periodic complementary binary sequence pairs based on differences set pairs was put forward.It can expedi-ently find plentiful periodic complementary binary sequence pairs.

Research for WSN routing algorithm based on novel multi-level minimal dominating clustering

Guang-chun LUO,Jiong LI

2007, 28(8): 128-132. doi:1000-436X(2007)08-0128-05

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The novel mult-level minimal dominating clustering arithmetic is the reprove of the random clustering arith-metic,we discussed the arithmetic of minimal dominating set,and developed a improved predigestion arithmetic of near minimal dominating set,reduced the workload of compute the minimal dominating set.After discussed the realize of minimal dominating for WSN.The test results validate the improve in the energy consumption.

Mobility-aware zoned MANET routing protocol

Rui LI,Ren-fa LI

2007, 28(8): 133-140. doi:1000-436X(2007)08-0133-08

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Based on requests of MANET and its applications,a mobility-aware zoned MANET routing protocol—MAFZP was proposed,which zoned by the distance to minID node and only a simple basic network topology was maintained.By using nodes' neighbors information smart and subtly,the protocol's request delay and control overhead were all descended to O(2R).Moreover,nodes' mobility patterns were also used to descend control overhead.At a result,the protocol's routing request delay and control overhead were very low.

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