Showing papers in "Communications Technology in 2011"
Journal Article•
TL;DR: A modified back propagation(BP) algorithm with additional momentum and self-adaptive learning rate is adopted to set up the initial parameters of the neural network, which could overcome the disadvantages of standard BP algorithm.
Abstract: A modified back propagation(BP) algorithm with additional momentum and self-adaptive learning rate is adopted to set up the initial parameters of the neural network,which could overcome the disadvantages of standard BP algorithm,such as slow convergence rate and easy fall into local minimum.The network sensibility to the local adjustment of error curved surface could be reduced and the local minimum suppressed efficiently by adding momentum item into the weight calculation formula,a self-adaptive learning algorithm is implemented,thus to adjust the learning rate according to the total error and shorten the training time and speed up the convergence rate.The improved algorithm is applied to recognising the handwritten characters,including numbers,English letters and some simple Chinese characters.The experimental results indicate that the proposed algorithm could achieve higher recognition accuracy,shorten the training time and has better robustness,as compared with the traditional BP algorithm.
7 citations
Journal Article•
TL;DR: For the deficiency of conventional discrete wavelet transform fusion algorithm in features of the image edge,DT-CWT some notable features, such as translational invariance, polydirectional selectivity and so on, are adopted to decompose and reconstruct the multi-focus images.
Abstract: For the deficiency of conventional discrete wavelet transform fusion algorithm in features of the image edge,DT-CWT some notable features,such as translational invariance,polydirectional selectivity and so on,is adopted to decompose and reconstruct the multi-focus images.According to the fusion rule,the study is focused on the high-frequency component.The low-frequency component only employs simple weighted average method,while the high frequency component uses the standard deviation as the fusion measure,and based on this,two kinds of image fusion algorithms are proposed.These algorithms are evaluated and compared in their performance parameters,and finally the optimum image fusion algorithm is achieved.
5 citations
Journal Article•
TL;DR: This paper disusses in detail the fast implementation of prime-field ECC, and analyzes such key techniques as Mersenne prime algorithm, Fermat theorem, Euclidean theory, and so on.
Abstract: With the extensive use of ECC,how to speedily implement ECC is always the focus of crypto industry.In certain applications such as mobile and wireless scenes,the speed is very important.Nowadays,there are various ways to implement ECC.This paper disusses in detail the fast implementation of prime-field ECC,and analyzes such key techniques as Mersenne prime algorithm,Fermat theorem,Euclidean theory,and so on.By this way,the fast implemention of prime-field ECC could be done.
4 citations
Journal Article•
TL;DR: Practical application indicates that the model could conquer the shortage of present storage mode, solve the problem of massive data storage, and effectively raise the storage efficiency.
Abstract: For the problem of massive data storage on the network,and based on the hadoop and virtual technologies,the massive data storage model based on could computing is proposed.The massive data of hospital informatization is applied on the hadoop platform and processed by MapReduce,the key algorithm of cloud computing,and finally the data is stored in the virtual pool.Practical application indicates that the model could conquer the shortage of present storage mode,solve the problem of massive data storage,and effectively raise the storage efficiency.
4 citations
Journal Article•
TL;DR: A new image segmentation algorithm in combination with Shuffled frog-leaping algorithm and FCM clustering is proposed, this algorithm could overcome the disfigurement caused by FCM algorithm, which is sensitive to initial clustering center and membership matrix.
Abstract: A new image segmentation algorithm in combination with Shuffled frog-leaping algorithm and FCM clustering is proposed,this algorithm could overcome the disfigurement caused by FCM algorithm,which is sensitive to initial clustering center and membership matrix.Shuffled frog-leaping algorithm(SFLA) is a bran-new heuristic colony optimization method,which has effective computing capability and excellent global searching capability.The experimental results indicate that the proposed algorithm could enhance the efficiency of image segmentation,and as compared with the algorithm of FPSO with FCM,could also achieve better image segmentation effect.
4 citations
Journal Article•
TL;DR: Theoretical analysis and simulation results show that the applied phase interferometer design and improvement is effective and feasible and beneficial to the real-time engineering implementation and is of reference significance in the practical engineering applications,particularly in phase Interferometer with long-base and multi-antenna array form.
Abstract: Complicated electromagnetic signal direction finding in the complex electromagnetic environment is necessary for electronic information detection.Considering technical difficulty in resolving angle ambiguity and antenna layout by the traditional digital phase interferometer,an applied phase interferometer method based on virtual baseline is proposed according to the basic principle of interferometer.By using the majority decision criterion to enhance the direction-finding performance,the direction estimation method is improved.Theoretical analysis and simulation results show that the interferometer design and improvement is effective and feasible.Meanwhile,this is beneficial to the real-time engineering implementation and is of reference significance in the practical engineering applications,particularly in phase interferometer with long-base and multi-antenna array form.
3 citations
Journal Article•
TL;DR: The article focuses on the core of IoT—WSN(Wireless Sensor Network), and gives a detailed description of WSN data acquisition, data processing, and wireless communications.
Abstract: The definition,components and service system of IoT(Internet of Things) is given first,thus the reader may have an overall understanding of IoT.And then,based on the description of sensor networks and RFID,which are used for data acquisition and in combination of the two major standards,ZigBee,WIA-PA,the article focuses on the core of IoT—WSN(Wireless Sensor Network),and gives a detailed description of WSN data acquisition,data processing,and wireless communications.Finally,the potential applications of IoT are forecasted,and the opportunities and challenges in the process analyzed.
3 citations
Journal Article•
TL;DR: The experimental result is fairly consistent with the above theoretical analysis, and the changes of the filter insertion loss and rectangular coefficient in the adjustable frequency range are analyzed.
Abstract: In this paper,a tunable filter circuit is described and the specific reasons of inductively coupled and parallel resonant circuit are explained.The equivalent circuit of varactor diodes is given,and the maximum frequency tuning range of filter constituted with varactor diodes is analyzed.AVHF-band electrically tunable filter with ADS software by agilent is designed and its operation band is 100～260 MHz,pass-band insertion loss 4dB,VSWR 1.65.The changes of the filter insertion loss and rectangular coefficient in the adjustable frequency range are analyzed.And the experimental result is fairly consistent with the above theoretical analysis.
3 citations
Journal Article•
TL;DR: The location system proposed in this paper could satisfy the design requirement of low cost, low power and high precision.
Abstract: With CC2431 wireless positioning engine as the core and combined with the ZigBee reference node,a wireless location system is designed.A ZigBee node(CC2430/CC2431) hardware platform is implemented,thus to minimize the hardware cost and reduce the equipment size.This system,with digital RSSI technology,accurately calculates the location of the node under test,according to the received signal strength and the location of known reference nodes,and could realize a positioning accuracy of 3～5 m and a resolution of 0.25 m.The location system proposed in this paper could satisfy the design requirement of low cost,low power and high precision.
3 citations
Journal Article•
TL;DR: A side channel attack against RSA-CRT implementation, relative to MRED, could reduce the number of needed power traces and raise the attack efficiency.
Abstract: As a fast RSA implementation,RSA-CRT is widely applied to computing-limited devices,such as smart cards.This paper describes a side channel attack against RSA-CRT implementation.By properly choosing input data,the power consumption of the intermediate value after the modular reduction is analyzed.This attack first determines the size of one of the primes,then based on it,takes another DPA attack and gets the byte-by-byte prime.The simulation experiment shows that this attack is effective,and relative to MRED,could reduce the number of needed power traces and raise the attack efficiency.
3 citations
Journal Article•
TL;DR: Experiment indicates that the proposed algorithm could effectively improve the accuracy and real-time performance of the target tracking.
Abstract: In order to solve the inaccurate locating caused by low differentiation between object color and background color and the missing object resulted from largely blocked area of the object,an improved algorithm is proposed.This algorithm,with Harris corner,could effectively extract target's corner characteristic,these corners are embedded into the iteration condition of meanshift,algorithm for object search,and then in integration of kalman filter,the position of the target in the next frame is predicted and the target tracking finally realized.Experiment indicates that the proposed algorithm could effectively improve the accuracy and real-time performance of the target tracking.
Journal Article•
TL;DR: The algorithm, though adjusting the step size parameters, makes the weight vector optimal,thus improves effectively the convergence rate and steady-state error performance.
Abstract: Based on brief discussion of basic LMS,by constructing a nonlinear function between the step factor μ and the error signal e(n) ,a new variable step-size LMS algorithm is proposed,along with the performance analysis with regard to different parameters.The algorithm,though adjusting the step size parameters,makes the weight vector optimal,thus improves effectively the convergence rate and steady-state error performance.The theoretical analysis and simulation results shows that this algorithm,as is of compared with the basic LMS algorithms and some similar variable step-size algorithms,faster convergence speed and smaller steady-state error.This further indicates that this new algorithm is superior to other algorithms.
Journal Article•
TL;DR: A new RSSI-based ranging localization algorithm is presented, which computes the location of approximate centroid with RSSI, then with it as reference node, adjusts the range, and locates the node.
Abstract: In wireless sensor network,the node self-localization is the foundation of target localization,and it includes two classes as distance-based and distance irrelevant localizations.The RSSI-based localization algorithm,for its easy implementation,is widely,but it has a fairly big error in distance ranging.The paper presents a new RSSI-based ranging localization algorithm,which computes the location of approximate centroid with RSSI,then with it as reference node,adjusts the range,and locates the node.Simulation results show that this algorithm is of better localization precision.
Journal Article•
TL;DR: This paper proposes one new double encryption-key mechanism, in which the DES encryption algorithm is employed to get application keys from encryption transform of the main keys, to provide reliable guarantees for the generation and management of the key in the database encryption.
Abstract: A key technology for database security is database encryption.Nowadays,one effective method for database encryption is to encrypt sensitive fields,and one sensitive field corresponds to a key,while the generation and security storage of the encryption key is the key problems.This paper proposes one new double encryption-key mechanism,in which the DES encryption algorithm is employed to get application keys from encryption transform of the main keys.The user just considers how to get secure storage of main keys,while considers no security storage and communication of the application keys.This natural combination integrating the security of the encryption algorithm and complex transformation generates the application keys,thus to provide reliable guarantees for the generation and management of the key in the database encryption.
Journal Article•
TL;DR: Experiment results show that the proposed algorithm has good performance in both invisibility and security, and also of good robustness to the noise, cropping,filtering,JPEG compression and other attacks.
Abstract: A digital image watermarking algorithm based on fast curvelet transform is proposed.Firstly,the carrier image is decomposed by fast curvelet transform,and then the watermarking image is scrambled by Arnold transform.Secondly,according to the human visual characters and curvelet coefficients the binary watermarking image is embedded into the medium frequency coefficients.Experiment results show that the proposed algorithm has good performance in both invisibility and security,and also of good robustness to the noise,cropping,filtering,JPEG compression and other attacks.
Journal Article•
TL;DR: Computer simulations show that this proposed multi-component LFM signal separation technology could greatly reduce the computational complexity,separate the L FM signal effectively and estimate the parameters correctly.
Abstract: Taking advantage of the energy concentration property of LFM signal in the fractional Fourier transform domain,the multi-component LFM signal separation technology based on the fractional Fourier transform is proposed in this paper.It detects the LFM signal by searching the peak in FRFT domain and separates this signal from the domain quickly.The separation effect is evaluated by the correlation coefficient.For the complexity of the 2D peak searching algorithm,the curve-fitting optimization technique is also proposed to implement FRFT modulus detection,thus reducing the 2D peak searching to a problem of 1D curve fitting.In addition,a Gaussian mixture model to approximate the distribution of FRFT modulus is described.Computer simulations show that this proposed method could greatly reduce the computational complexity,separate the LFM signal effectively and estimate the parameters correctly.
Journal Article•
TL;DR: With wavelet decomposition, pulse wave can be decomposed into various dimensions of the coefficients and recomposed according to the low-frequency coefficient of the bottom and the high-frequency coefficients of various layers.
Abstract: Pulse wave is complex,and its measurement is easily impacted by noise,so the reduction of pulse wave noise is a very important processPulse wave is not a smooth process and spreads a big noise pollution,and traditional filter is limited in reducing pulse wave noiseWith wavelet decomposition,pulse wave can be decomposed into various dimensions of the coefficients and recomposed according to the low-frequency coefficient of the bottom and the high-frequency coefficients of various layersIn the process of pulse wave recomposition,the coefficients related to noise could be rejected while the valuable information in the signal maintained
Journal Article•
TL;DR: Simulation results prove the correctness of the designed modules, and these modules can meet the requirements of speed and accuraccy, and BER of the maximum free distance nonmalignant convolutional code in AWGN channel is analyzed.
Abstract: Firstly,the theory of(2,1,2) convolutional code and the process of Viterbi decoding are described.In addition,FPGA(Field Programmable Gate Array) is employed to implement encoder and Viterbi decoder.Simulation results prove the correctness of the designed modules,and these modules can meet the requirements of speed and accuraccy.Then BER(Bit Error Rate) of the maximum free distance nonmalignant convolutional code in AWGN channel is analyzed.Simulation with Matlab indicates that the convolutional code is powerful in correcting errors,and BER is increasingly reduced when the constraint length of the convolutional code become large,that the convolutional decoder is small in designed output delay,occupies fewer resources,and is of certain practical value.
Journal Article•
TL;DR: A DFT-based LS channel estimation algorithm is proposed, which with the estimation of the noise power variance, could achieve a threshold and thus remove the noise further and improve the performance of channel estimation.
Abstract: Accurate channel estimation in multiple input multiple output orthogonal frequency division multiplexing(MIMO-OFDM)systems is the key to improvement of the system performance.For deficiency of the existing channel estimation algorithms,a DFT-based LS channel estimation algorithm is proposed,which with the estimation of the noise power variance,could achieve a threshold and thus remove the noise further.This algorithm by taking full advantage of correlation between time domain and frequency domain in time variant wireless channel,could improve the performance of channel estimation.Simulation results show that the proposed method is of low complexity and could further raise the accuracy of channel estimation under slow time-varying channel environment.
Journal Article•
TL;DR: A novel fast phase calibration method, aimed at quick satellite drifting and difficult acquisition of strongest signal in Launch Early Orbit Phase (LEOP), which requires no finding of autotracking zero point and could be finished through one-time movement of the antenna in co-ordination with program tracking file in LEOP.
Abstract: A novel fast phase calibration method is proposed,aiming at quick satellite drifting and difficult acquisition of strongest signal in Launch Early Orbit Phase(LEOP)Based on dual-channel tracking receivers,the theory of fast phase calibration is analyzed,and its function is realized through softwareThis method requires no finding of autotracking zero point,and it could be finished through one-time movement of the antenna in co-ordination with program tracking file in LEOPThe time for calibrating phase is not more than 5 secondsThe results show that this calibration could meet the requirements of LEOP
Journal Article•
TL;DR: This inter-vehicle wireless data exchange system implements wireless data transmission based on STC12C5a60S2 and CCll01 and is of good performance in static and low-dynamic environment.
Abstract: Considering unceasing development of the wireless communication technology in inter-vehicle communication,an inter-vehicle wireless data exchange system is proposed,and a study on the static and dynamic properties of the inter-vehicle wireless data communication module is doneEarly theoretical and experimental research is aimed at using this technology on the vehicle collision warning systemThis system implements wireless data transmission based on STC12C5a60S2 and CCll01The design of hardware and software and the work principle of this system are givenThe connection module is described emphaticaIlyThe experiment indicates that this system is of good performance in static and low-dynamic environment
Journal Article•
TL;DR: The Gigabit ethernet switch based on BCM53114S and BCM54684 chip is designed and the chips for the system are highly integrated, being easy for construction of network with spaning-tree function, automatic VLAN cutting, fast fault detection and recovery.
Abstract: The Gigabit ethernet switch based on BCM53114S and BCM54684 chip is designed.The whole system includes core control module,reset module,power supply module,configuring module.The most prominent feature of this design is the compatibility of Gigabit ethernet to the existing 10/100M ethernet.The chips for the system are highly integrated,thus being easy for construction of network with spaning-tree function,automatic VLAN cutting,fast fault detection and recovery.In hardware design of this project,high-integrated PBGA chips are applied in the modular design with good effect of EMC.
Journal Article•
TL;DR: The technology and mechanism evolution of the access and core transmission network is explored and the PTN's introduction is a step-by-step process from the core layer to the access layer of the transmission network.
Abstract: As the most complex and largest basic network of the operator,the smooth evolution and compatibility of transmission network is the most critical issueIn this paper,based on analysis of the classification and characteristics of the 3G transmission network,the technology and mechanism evolution of the access and core transmission network is exploredGenerally,in the course of evolution,the different 3G transmission schemes should be adopted according to network conditions and demands of the different periods,the PTN's introduction is a step-by-step process from the core layer to the access layer of the transmission network
Journal Article•
TL;DR: The authors suggest that the further study should mainly focus on survivability of the intelligent optical network, integration of the traditional optical network and intelligent Optical network, and routing algorithm of the integrated optical network.
Abstract: Stimulated by science and technology development and market demand,the intelligent optical network achieves a rapid development.Evolution,present situation,and development of the intelligent optical network are described in this paper.The authors suggest that the further study should mainly focus on survivability of the intelligent optical network,integration of the traditional optical network and intelligent optical network,and routing algorithm of the integrated optical network.
Journal Article•
TL;DR: It is pointed out that the CBTC system, by adoption of advanced communication technology, would lead the future development of modern city railway traffic and communication signal.
Abstract: Study on communication-based train control system is conducted,the critical role of CBTC system in realizing high-precision positioning and control of the train through the successive,high-speed,bidirectional data communication between the vebicle equipments is analyzed,the basic principle,characteristics and system structure are described,several wireless communication solutions is CBTC system are compared and analyzed,the optimal solution by adoption of leaky coaxial cable and radio mixed network is concluded.Finally this paper points out that the CBTC system,by adoption of advanced communication technology,would lead the future development of modern city railway traffic and communication signal.
Journal Article•
TL;DR: A novel quintuple model for Chinese text sentiment orientation is proposed, which improves the accuracy of text sentiment Orientation judgment and gives the definition and process for estimation of sentence sentiment orientation.
Abstract: Today,the estimation of text sentiment orientation increasingly becomes the hotspot and difficulty in technical researchSentiment orientation model is the foundation for this estimationThus a novel quintuple model for Chinese text sentiment orientation is proposedThe model,from the five aspects of orientation viewpoint holder,orientation subject,orientation standpoint,orientation object and orientation category,protrays the notion of Chinese text sentiment orientation,enriches sentiment orientation expression,improves the accuracy of text sentiment orientation judgmentAnd based on this model,this paper gives the definition and process for estimation of sentence sentiment orientation
Journal Article•
TL;DR: This method, based on distributed file system realized in Java, provides a convenient and flexible framework for distributed storage system on a cluster of commodity machines and could simplify the design of distributed image storage service system and improve the performance and reliability of the system.
Abstract: This paper analyzes in detail the three basic characteristics of distributed file system,including the classification of multi-node servers,the data distribution,and the communication between the multi-node servers.Based on this,a method for realizing the service of image storage is proposed,which is based on distributed file system realized in Java.This method,with Hadoop as the foundation and by the features of HDFS(Hadoop Distributed File System),provides a convenient and flexible framework for distributed storage system on a cluster of commodity machines.The method could simplify the design of distributed image storage service system and improve the performance and reliability of the system.
Journal Article•
TL;DR: Simulation results show that in the different HF environment, the balance of implementation efficiency and reliability should be considered in the design of data-rate control mechanism.
Abstract: Data-rate control mechanism could effectively solve the restraint of between the transmission reliability and transmission rate in HF channel.The data-rate control procedure described in STANAG 5066 is analyzed and the implementation of data-rate control in special scenarios is studied.And two data-rate control algorithms are provided and simulated.Simulation results show that in the different HF environment,the balance of implementation efficiency and reliability should be considered in the design of data-rate control mechanism.
Journal Article•
TL;DR: The experiments show that the proposed algorithm could remarkably improve execution efficiency of the traditional Apriori-based algorithm, and enhance the expansibility of the apriori- based algorithm.
Abstract: The association rule,based on the degrees of support and confidence for the choice of useful rule,is one of the important means for data mining.The traditional Apriori-based algorithm of association rules due to the frequent computing k-itemsets on the database,is in large overhead.For the deficiency of Apriori-based algorithm,MapReduce software framework is improved and the Apriori-based algorithm is accordingly proposed,thus to enhance the expansibility of the apriori-based algorithm.The experiments show that the proposed algorithm could remarkably improve execution efficiency of the traditional Apriori-based algorithm.
Journal Article•
TL;DR: A gateway program is designed to solve the interconnection and integration of the two simulation system with different archeteclurs, and realize bidirectional information exchange between MAK-RTI and DDS without any change of each system, which could effectively solve the problem of joint simulation withMAK- RTI and RTI-DDS.
Abstract: First the communication interfaces of the two systems based on RTI-DDS and MAK-RTI are studied.Then a gateway program is designed,thus to solve the interconnection and integration of the two simulation system with different archeteclurs,and realize bidirectional information exchange between MAK-RTI and DDS without any change of each system,this could effectively solve the problem of joint simulation with MAK-RTI and RTI-DDS.Finally an example in integrating the two systems of MAK-RTI and DDS is presented.