Showing papers in "Journal of Nanjing University of Posts and Telecommunications in 2010"

Security Characteristic and Technology in the Internet of Things

Abstract: Security and privacy are key issues for application in Internet of Things.Based on confidentiality,integrity and availability,this paper analyzes the security characteristics and problems in IOT.It discusses a framework and some techniques,including the key management,authentication,access control,security routing,privacy protecting,intrusion detecting and tolerance.

Tomlinson-Harashima Precoding Design with Imperfect Channel State Information

Abstract: Channel state information(CSI) affects the performance of Tomlinson-Harashima precoding(THP).For actual time-varying multi-input multi-output(MIMO) channels,there is imperfect CSI at both ends due to estimation errors at the receiver and estimation errors,feedback delay at the transmitter.A THP design over transmitter and receiver spatial correlation is proposed,which uses zero-forcing(ZF) THP criteria and combines with Bayes' estimation theorem.Simulation results show that the proposed THP can effectively decrease the unfavorable influence caused by spatial correlation,channel estimation errors,feedback delay and time variations,and has better bit error rate(BER) performance.

Random Matrix Theory and Wireless Communication

Abstract: First,mathematical background of random matrix theory related to wireless communications is introduced;then the relationship between random matrix theory and wireless communications is addressed,and the question why the random matrix theory is important to wireless communications is answered;Finally,we take the performance analysis of DEC receiver with large dimensional system as an example,showing the huge power of random matrix theory to deal with the issues in wireless communications.

Study of Compressive Sensing Based Sparse Channel Estimation in OFDM Systems

Abstract: A new method of orthogonal frequency division multiplexing(OFDM) sparse channel estimation based on compressive sensing(CS) is proposed.One of the CS algorithms,orthogonal matching pursuit(OMP),is used to estimate the channel impulse response of OFDM system.Simulations have shown that the OMP estimation has good performance but with less pilots than conventional least square estimation.Therefore,the spectral efficiency of the system can be improved.In OMP estimation,the optimal number and optimal location of pilots are ascertained by simulations and basic CS theories.

An Overview of Active Microwave Imaging for Early Breast Cancer Detection

Abstract: First,this article reviews the background of microwave imaging for early breast cancer detection,with a focus on active methods.Then active approaches,namely microwave tomography and radar-based microwave imaging,to microwave breast cancer detection are overviewed briefly,where there are recent developments in imaging algorithms as well as antennas,models,phantom and experimental systems.Lastly,we give concluding remarks and future research.In a word,the main objective of this article is to provide an overview of the principles,development,and current research status of these approaches.

Date Fusion Schemes Based on Cooperative Spectrum Sensing

Abstract: In cognitive radio(CR) systems,cooperative spectrum sensing is conducted among the cognitive users so as to detect the primary user more accurately.How to fuse the data from different cognitive users is a key issue of cooperative spectrum sensing.Existing fusion techniques can be divided into two types: decision fusion and data fusion.Five fusion methods based on decision fusion and data fusion are investigated in this paper,we use them to sense spectrum cooperatively in CR networks and their spectrum detection performances are compared.Five fusion methods are both studied and the analytical performance results are given.Simulation results show that the sensing performance is improved significantly compared to the conventional spectrum sensing and data fusion schemes exhibit much better performance than decision fusion.

Internet Traffic Forecasting Based on BP Neural Network

Abstract: The time series of network traffic data was modeled and forecasted based on BP neural network.The IP network traffic forecasting model based on BP neural network was built by analyzing the characteristics of network traffic.The experimental results prove that the model is efficient in network traffic prediction with good astringency and stability.

A Survey of Rational Secret Sharing Schemes

Abstract: Rational individuals in a secret sharing scheme always choose their strategies according to expected payoffs.The research of secret sharing schemes meets many new challenges due to the concerning of rational individuals.However,as a new direction of the research field,there are many open problems waited to be solved.In this paper,the utility assumption are introduced,the classic schemes of rational secret sharing are discussed and compared in detail.In the last,the open research problems and the possible solution are pointed out.Recent related work indicates that future work will focus on the combination of security and computable in rational secret scheme in complex access structures using asynchronous communication channel.

Research on Security Architecture and Key Technologies in Cyber-Physical Systems

Abstract: Through the analysis of challenges and threat model,this paper proposes a novel security architecture for cyber-physical system(CPS).It discusses then the associated security tecnologies for CPS,including privacy preserving,secure control and vulnerability assessment.Based on a summary of existing research topics,the paper describes some future research directions.

A Voice Conversion Algorithm in the Context of Sparse Training Data

Abstract: A new voice speaker conversion algorithm is proposed.The algorithm evaluates the parameters of Gaussian mixture model(GMM) by Variational Bayesian(VB) theory and applies it to the track spectral parameter mapping processfor voice conversion(VC) to realize the speaker conversion.The advantage of introducing VB into VC community lies in its ability to overcoming the over-fitting problem when the training data is not sufficient.Moreover,using the probability based evaluation approach,the parameters are estimated globally instead of by point estimation.It makes VB more accurate than the traditional ones such as Maximum Likelihood(ML) or Maximum a Posterior(MAP).Subjective and objective evaluation both demonstrate that the proposed algorithm based on VB works quite well,especially when the training data is sparse.In addition,the quality and the speaker individuality of the converted speech feels much better in comparison to the traditional VC system.

Analysis on Aggregation Interference in Cognitive Networks Based on In-band Spectrum Sensing

Abstract: Analysis on aggregation interference in cognitive networks based on in-band spectrum sensing is presentedFirstly,In-band spectrum sensing is adopted to reduce the cost of spectrum resource and signalsThen a statistical model of interference aggregation in primary receiver is developedIn particular,the signal-interference radio is evaluated with the parameters such as sensing region,distance between primary systems as well as the path loss exponentsIt's shown that,based on the interference aggregation model,the utilization of spectrum resource is improved and the interference to the primary is reduced

An Index Structure for Moving Objects on Road Network

Abstract: In order to improve the efficiency of querying the object location on traffic road,referencing the idea of FNR-tree and improving it,this paper designs a new index structure DEI(Dynamic and Efficient Index) for moving objects on road network,which uses the technologies such as hash tables,dynamic arrays,B-tree,the single round-robin list.The manipulation algorithms of it are also designed.DEI has three partitions:hash partition of roads,structure of tine information and the hash structure of moving object.DEI supports the queries like searching for the history,present and future location of moving objects.It can quickly find the Location of moving object.The performance of the DEI has been proved by the experimental results.

Research and Design of Smart Campus Based on Internet of Things

Abstract: This paper proposes the concept of Smart Campus and related design methods.Based on the technology about Internet of Things and supporting environment,the strategy of overall design and architecture for smart campus are given.The related implementation techniques are analyzed and discussed.To ensure Smart Campus in maintenance well,the effective operation system with the concrete means is also explained.The research and deployment of Smart Campus brings the positive effect for the establishment of an information campus.Then the key competitive power of the university is enhanced.

Research of P2P Traffic Identification Based on Neural Network Ensemble

Abstract: A novel P2P traffic identification method based on neural network ensemble is proposed.A P2P flow detection model is developed by using correlation-based feature selection(CFS) algorithm to extract P2P flow characteristics,and utilizing six ensemble neural networks by dynamic weighted integration method.Through experimental comparison between this proposed model and traditional methods,such as single BP neural network,decision tree,bayesian,and support vector machine,it is shown that the proposed method has a better P2P traffic identification accuracy and stability.

A Fast Algorithm for Pre-procedure of Method of Moments

Abstract: A fast algorithm is proposed for finding common-edge of a pair of adjacently triangular patches in the pre-procedure of the method of moment,with which the surface integral equation is solved.The fast algorithm is based on the concepts of adjacent matrix and incidence matrix in the graph theory.The computational complecity for finding the common-edges in the algorithm is O(N),which is verified by numerical simulation.This algorithm is especially suitable for dealing with the pre-procedure of very large scale computational electromagnetic problems.

A Particle Swarm Clustering Protocol for Wireless Sensor Networks Based on Optimal Number of Clusters

Abstract: Clustering protocols for layer-cluster wireless sensor networks are discussed.Following the study of classical LEACH protocol with its defects analyzed,the ILEACH protocol is proposed.In the initial stage,ILEACH protocol calculates the optimal number of clusters as a target for clustering with certain principles.In the cluster reorganization stage,residual energy and location distribution of nodes are taken into account to select a new cluster head with particle swarm optimization algorithm.Encouraging results are achieved.Simulations have shown that ILEACH protocol can save energy effectively and prolong the lifetime of network greatly.

A Novel Non-Reconstruction Algorithm Based on Compressed Sensing for Spectrum Detection

Abstract: A novel non-reconstruction spectrum detection algorithm based on compressed sensing is proposed.The measurements from the compressed sensing process are directly used for the primary user detection to address the wind-band spectrum detection problem.We quantitatively analyze the performance of detection,and improve it by cooperative spectrum detection.Simulation results show that the new algorithm has good detection effect where SNR is above 0 dB.Cooperative spectrum detection can be an effective acternative to improve the algorithm performance under low SNR.Meanwhile,compared with the algorithm based on reconstruction,the proposed algorithm greatly reduces the amount of data and algorithm complexity,and significantly reduces the detection time.

A Method of Component Extraction Based on Function Dependence Graph

Abstract: Based on function dependence graph,we propose a method of component extraction in this paper.First,we discuss some relations of dependence in a function dependence graph as well as their representations in a graph.Then,A sub-graph will be generated by doing slicing operations to the function dependence graph which is generated through parsing the source codes.Combining the source codes and the sub-graph,the sliced codes which are the result of component extraction can be generated.we also propose a method of computing the degree of cohesion and coupling based on function dependence graph to evaluate the qualities of the sliced codes from the point of software metrics.Experiments prove that the sliced codes generated by the method in this paper are more efficient.

A Pricing Function Based Power Control Game Algorithm for Cognitive Radio

Abstract: Based on the non-cooperative power control game(NPG) proposed by David Goodman.,an improved pricing function is adopted and a power control game algorithm suitable for cognitive radio system is proposed.Then the existence and uniqueness of the Nash equilibrium are proved for the proposed algorithm.The simulation results have shown that,in comparison to several classical distributed algorithms,the proposed algorithm not only reduces the transmit power and improves the user's utility but also speeds up the convergence.Therefore it fits well to the cognitive radio system with high demand of time-delay characteristic.

Frequency-domain Parameter Identification of Exciting System Based on Support Vector Machine and Particle Swarm Optimization Algorithms

Abstract: A frequency-domain parameter identification method based on SVM(support vector machine) and PSO(particle swarm optimization) algorithms is proposed to identify the parameters of exciting system.First,the feature samples are selected by SVM regression algorithm.Then the parameters of exciting system are identified by the PSO algorithm using the feature samples instead of all samples.The calculation time of the PSO algorithm is reduced and the accuracy of the model identified is increased by use of feature samples.The example based on measured data shows that the proposed method is simple to be implemented and can get better identification results under both simple model and complicate model.

An Analysis of the 60 Years Studying Abroad History and Characteristics

Abstract: Since the founding of new China,the 60 years overseas education has undergone the rush for studying in the Soviet Union,the interruption of studying abroad during the cultural revolution,the study-abroad by public expense at the beginning of reform and opening up,public overseas education since the late 1980s and returning home in the new period.Overseas education,which enriches students'lives and changes their own destiny deeply,keeps records of new historical changes of Chinese society at the same time.During the 60 years since the founding of PRC,overseas education and students returning home have influenced value orientation of Chinese social reform to a large extent,becoming one of the driving forces for social progress.

IOT and Its Technology Development

Abstract: This paper focuses on the Internet of Things(IOT),which is a research hot spot in the domestic and abroad ICT field.The paper introduces the evolution process of IOT,basic concept,some related key technologies,and standardization action.Some proposals for the development of IOT related technologies and IOT industry are also described.

Empirical Analysis of the Financial Crisis Contagion Effects Based on Variable Structure Copula Model——An Example of Sino-US Stock Market

Abstract: In order to test the U.S financial crisis's impact on China's stock market,we carry out Granger causality test,and then use the variable structure Copula model to estimate the correlation of Sino-US stock market.The results show that the relevance of them was larger than that before the U.S financial crisis happened,the correlation was changed from time to time,the contagion effects was only exit in the first stage of the crisis,and in the last two stages after the crises happened the contagion effects was not found.

A Survey of Identity-based and Attribute-based Cryptography

Abstract: We survey the state of research on identity-based cryptography and attribute-based cryptographyWe firstly review the basic concepts of identity-based cryptographic schemes in which users' identifier information such as email or IP addresses instead of digital certificates can be used as public key for encryption or signature verification,and subsequently review some important identity-based encryption,signature and signcryption schemesThen we give our research on Identity-Based Encryption-Signature(IBES) methodWe also survey the attribute-based cryptographic schemes in which the identity of user is viewed as a set of descriptive attributes,including some important attribute-based encryption and signature schemesWe subsequently give our research on Attribute-Based Encryption and Identity-Based Signature (ABE-IBS) methodBoth methods aim at efficiently improving the security of wireless sensor networkFinally,we propose a few interesting open problems concerning with practical and theoretical aspects of identity-based cryptography and attribute-based cryptography

Theoretical Study of Image Processing Based on Medium Mathematics Systems

Abstract: Medium mathematics system is an effective mathematical tool to process vague phenomenaThis paper enlarges the data area for measuring the medium truth scale to a symmetrical zoneConsidering the features of images and taking into account of the medium truth scale,this paper studies the benchmarks for the gray level of a single pixel and image set,the similarity between two pixels and that of between two image setsWe define the image medium entropy and can determine the image fuzzy scale by the image medium entropyMoveover,this work presents a novel numerical method based on the medium logic for image processing

Electronic Commerce: Concepts,Mistakes and the Future

Abstract: Electronic Commerce is a new commerce model and a new branch of learning.Correct concepts of electronic commerce are the basis of e-commerce application and e-commerce education.In this paper,how to understand the meaning and inbeing of electronic commerce is first discussed.On the basis of this,some main mistakes in the basic concept of electronic commerce are analyzed,combined with the discussion of some problems in e-commerce application and e-commerce education in China.Then the future of electronic commerce is considered from the aspect of e-commerce application and e-commerce education.

An Analysis of the International Academic Influence of Academic Journals in China over the Three Decades since Reform and Opening Up

Abstract: Academic journals,by which academic influence of a country is indicated,provide important sources for research.The number of papers collected by the three US science citation databases(SCI,SSCI,AHCI) is an important index of a discipline's international academic influence.An analysis of academic papers indexed by the three science citation databases over the last three decades in our country reveals that great gaps exist in the number of papers indexed by each database,which embodies great imbalance in the development and international academic influence of the three subjects,of which natural science developed at a high speed,social science developed rapidly,and art and humanities developed slowly.In order to enhance the international academic influence of our country,policies should be stipulated to balance the development of different subjects.The way to classify subjects should be reformed: the philosophical social science should be divided into two subjects——social science and art humanities.Correct methods should be used in evaluating different subjects and measures should be taken to assist academic journals in entering international citation databases and thereby promote the internationalization.

Morphing Arithmetic of Pitch and Application in Voice Morphing System

Abstract: This paper proposes an efficient morphing algorithm of pitch based on generalized artificial intelligence and the STRAIGHT model.The STRAIGHT model can modifies the pitch without loss of the quality of the voice.Moreover,based on GANN predictable ability,we can get the relationship between source and object,and realizes pitch conversion.Subjective evaluation and objective measurement indicate that the performance of the proposed method is better that that of the traditional method in term of synthesized quality and precision of mapping target characteristics.

Spatial-Temporal Adaptive Error Concealment Algorithm for H.264 Based on Accurate Scene Change Detection

Abstract: Aiming at the performance degradation of H.264 error concealment(EC) scheme when scene changes(SC),this paper proposes a spatial-temporal adaptive EC scheme based on SC detection.First,our scheme detects if SC occurs in the current corrupted I/P frame using the difference of histogram or Intra MB ratio,and conceals current I/P frame using novel spatial EC algorithm based on mode estimation if SC occurs,otherwise using improved temporal EC algorithm.Experimental results show that our scheme can conceal lost MB by adaptively using temporal/spatial correlation,and improves the recovery quality of current frame and effectively prevents error propagation,thus improves the recovery quality of the whole sequence.The scheme has low computational complexity and is suitable for real-time applications.

An Efficient Cooperative Spectrum Compressed Sensing Scheme for Wideband Cognitive Radio

Abstract: Combining compressed sensing,cooperative spectrum sensing and data fusion together,this paper presents a new type of efficient cooperative spectrum sensing scheme based on compressed sensing theory.We not only use the cooperative probability of sensing,cooperative probability of false alarm to evaluate the spectrum detection performance of a single subchannel,but also propose to use probability of system fullness and probability of false blocking to evaluate the spectrum sensing performance of the whole wide-band cognitive radio system.The simulation results show that compressed sensing can reduce the amount of data to be processed while keeping good reconstruction of the signal.