A novel scheme to generate an optical millimeter-wave and a full-duplex radio-over-fiber system by using one optical modulator was proposed and experimentally demonstrated.A mixer was employad to generate electrical millime-ter-wave,and single-arm electronic-optical modulator to generate double sideband signals.Then an optical interleaver is employed to separate the spectrum of the double-sideband signals.The separated first-order sidband modes were used to generate optical millimeter-wave with double RF frequency,while the separated optical carrier was reused for upstream connection.The experiment results show that the 40GHz optical millimeter-wave will be generated by 20GHz RF re-source,and 2.5Gbit/s downstream and upstream data can be transmitted over 20km in fiber.
Virtual machine introspection(VMI)has been widely used in areas such as intrusion detection and malware analysis.However,due to the existence of semantic gap,the generality and the efficiency of VMI were partly influenced while getting internal information of a virtual machine.By analyzing the deficiencies of existing technology of semantic gap restoration,a method called ModSG was proposed to bridge the semantic gap.ModSG was a modularity system,it divided semantic restoration into two parts.One was online phase that interact directly with user to construct semantic views,the other was offline phase that only interact with operating system to parse high-level semantic knowledge.Both were implemented via independent module,and the latter provided the former with necessary kernel information during semantic view construction.Experiments on different virtual machine states and different kernel versions show that the ModSG is accurate and efficient in narrowing semantic gap.The modular design and deployment also make ModSG easily to be extended to other operating systems and virtualization platforms.
In order to reflect the actual case of human decisions and solve the data sparseness problem of traditional col-laborative filtering recommendation algorithm, a trapezoid fuzzy model based on age fuzzy model was proposed. In this model, crisp point was fuzzified into trapezoid fuzzy mber and the fuzziness and information of users' grade was taken into account when calculating user's similarity by trapezoid fuzzy number. Based on this model, the user fuzzy similari-ty-based collaborative filtering recommendation algorithm was designed. The algorithm was proved to be an extension of traditional collaborative filtering algorithm in fuzzy fields. The experimental results show that, the proposed algorithm performs better when implemented in the sparse dataset with more user than item, and its running time is much less than traditional collaborative filtering algorithm.
To consider the problem of DOA estimation in coherent environment, the most important issue is to try to eliminate the rank loss of the spatial covariance matr x. The influence of coherent signals on the subspace-based ul-tra-resolution DOA estimation algorithm was analyzed. Then a signal-subspace based ESPRIT-Like algorithm was pro-posed from the thought of matrix reconstruction. The simu ion results demonstrate the validity and superiority of the proposed algorithm.
An approach for Chinese named entity identification using cascaded hidden Markov model,which aimed to incorporate person name,location name,organization name recognition into an integrated theoretical frame was presented.Simple named entity was recognized by lower HMM model after rough segmentation and complex named entity such as person name,location name and organization name was recognized by higher HMM model using role tagging.In the test on large realistic corpus,its F-1 measure of person name,location name and organization name was 92.55%,94.53% and 86.51%.In the first international word segmentation bakeoff held by SIGHAN (the ACL Special Interest Group on Chinese Language Processing) in 2003.ICTCLAS,which name entity identification base on this model achieved excellent score.
The original particle swarm optimization (PSO)algorithm has the advantages of fast convergence,but with the shortcoming of premature and local convergence.To overcome this problem,a new chaos-particle swarm optimization algorithm was presented,which was different from the conventional method of replacing pre-particle.Instead,the algorithm in this paper made the motion of particles with characteristics of chaos，so as to make particles move between the state of chaos and stable,and gradually close to the optimal value.The nonlinear dynamics of the proposed Mathematical model are analyzed,and the results of the experiment show that the proposed algorithm can result in encouraging results.
The obvious wrong segmentation in the existing two-dimensional histogram vertical segmentation method was pointed out.A new two-dimensional histogram oblique segmentation method was proposed,in which the histogram was divided into inner,edge and noise parts by four paralleled oblique lines.The image was thresholded by the oblique line which was perpendicular to the main diagonal.Then the formulae and its fast recurring algorithm of the two-dimensional histogram oblique segmentation method were deduced.Finally,the thresholded images and processing time were given in the experimental result and analysis,which were compared with those of Otsu fast algorithms.The results show that the two-dimensional histogram oblique segmentation could be used in nearly all the two-dimensional histogram thresholding.It makes the inner part uniform,the edge accurate in the thresholded image and has better tolerance capability to noise.At the same time the running time is significantly reduced.
With the development of cloud computing，the security issues of cloud computing are being more and more focused.In this paper，some types of security-related problems and their solutions of cloud computing are being comprehensively analyzed.Firstly，this paper describes the architecture of cloud computing and then compares the difference of cloud computing security and the traditional security，focusing on the technology of cloud computing security，and finally elaborate the key research areas and results of current cloud computing security from the perspective of cloud computing standard organizations and products.
Based on the Logistic-map,an optimized method of generating the spread-spectrum sequences was proposed.An initial value was given and iterated in the Logistic map,then L bit qualification was done to every point,in this way,new spread spectrum sequence would be achieved by shorten.It was compared with conventional chaotic code and Gold code and finally simulated in the DS-CDMA systems.Experiment results show that the iterative times are reduced,the calculating speed is improved,the spread-spectrum sequences can be reshaped with any length and the number of these sequences is larger than Gold sequence in being.The best quantification order is got too.
A novel coupled tent maps-based spatiotemporal chaotic cryptographic Hash function was proposed. Compared with the discrete tent map, the coupled discrete tent spatiotemporal chaotic maps have longer computer-realization-period, nearly uniform distribution and desired diffusion and confusion properties. Based on the coupled discrete tent spatiotemporal chaotic maps, a cryptographic Hashing function is constructed to generate 128-bit Hash value from a message with arbitrary length. The approach uses the initial value of coupled discrete tent chaotic dynamical system iteration as the secret key. The key space is very large. There is a high sensitivity and complex and strongly nonlinear coupling relation between the Hash value and the corresponding message and secret key. Theoretic analysis and simulation results are shown that the approach possess not only extremely high security in comparison with earlier chaotic Hash functions, but also the high execution speed. Therefore, the approach can satisfy all the performance requirements of Hash function, such as one-way, key sensitivity and collision resistance.
In order to deal with the safety hidden trouble caused by that the nodes in wireless sensor networks were lack of fixed infrastructure and it was hard to check the malicious behavior of the nodes,so the conception of nodes’ trust was proposed combined with swarm intelligence optimization algorithm.It introduced nodes’ trust as a allocation strategy of pheromone,which was similar to a reliable and secure label of MPLS,so as to set up the reliable and secure route,remove the malicious nodes from the network,and provide reliable and secure wireless sensor network environment.Simulation experiments show that it can effectively resist the wormhole attack,which is lack of effective methods to resist at present.
Cloud computing is a new method sharing infrastructure which provides the usage of service,application,information and infrastructure composed of “resource pool”computing,network,information and storage.The features of cloud computing directly impact the security threats of its environment and relative security policies,which include the self-service on demand,broadband access,visualization resource pool,quick elastic architecture,measurable services and multi-tenant.Cloud computing could definitely introduce positive effect because it has multiple benefits from scale economy to application availability.Nowadays,more and more enterprise users are ready to be involved in the cloud circle with the support of cloud computing providers and advocates.However,cloud computing also brings some new security issues.The security problem is very important since a large number of users share the IT infrastructure.In this paper,the specific cloud computing security requirement and solution are analyzed.The current status of international and domestic research and products are presented.
Firstly,the measurement based on mean RSSI and LQI was suggested by analyzing the disadvantages of traditional link measurement,and the more accurate information of link communication quality can be gained by measuring and computing the mean RSSI and LQI,secondly,different experiments with changed transmission power,hardware calibration,dynamic environments and concurrence interference had been tried to analyze the performance of the measurement based on the mean RSSI and LQI,at last,the sensitivity of link measurement had been defined,and the sensitivity values of the mean RSSI and LQI were computed,then a comprehensive weight between RSSI and LQI was made for measurement of link communication quality and performance evaluation in WSN.
The principle by which to analyze computer network attacks using attack graph was introduced.An attack graph generating algorithm was proposed.The computer network system risk assessment methods were studied using the attack graph model.A virtual computer network environment was introduced by which the attack graph generating algorithm and computer network system security methods were validated.
Three approaches were put forward to improve the poor locating performance of DV-Hop algorithm which is one of the range-free algorithms in wireless sensor network (WSN) with a dynamic topology. Firstly, the average one-hop distance among beacon nodes was refined by means of least squares method (LSM). Secondly, the average one-hop dis-tance used by each locating node for estimating itself location was modified through weighting the N received average one-hop distances from beacon nodes. Finally, the iterative numerical method with the initial values of estimated node locations was presented by setting proper threshold. The procedure of the iterative locating algorithm based on modifying average hopping distances and the simulation results were also shown. It can be concluded that the improved algorithm has obviously better locating performance in locating precision and precision stability at the cost of increasing appropriate communication and computation overhead, and is a more feasible locating scheme in WSN with both random distributing nodes and dynamic topology.
A novel method based on empirical mode decomposition (EMD) and ARMA was proposed to model and fore-cast self-similar networking traffic.The results demonstrate that EMD had the function of getting rid of the long range dependence(LRD) in traffic data.Therefore,the self-similar traffic processed by EMD could be modeled and predicted well by using ARMA which was a short range dependent(SRD) model.Moreover,the complexity of the proposed method was reduced sharply and the prediction precision was higher than radial basis function neural network.
Since traditional methods was not suitable for detection of small DDoS attack and identify of busy traffic, based on the influence of DDoS attack , one wavelet analysis method was proposed. Wavelet method of coefficient vari-ance analysis was deduced and software model for the method was designed. In addition, key issues of the choice of wavelet and calculation of Hurst were resolved. The experimental results show that the proposed method has more ad-vantages in accurately identify busy traffic and detection of small DDoS attack.
In real measurement environment, some factors of multi-path, diffraction, obstacles, etc., propagation losses produced location errors in the positioning process by RSSI technology. Through analyzing error range in 3D space, a new spatial locating algorithm ERSS based on RSSI was proposed. The ERSS algorithm had the advantages: locating calculation simplicity, no extra communication cost on the locating process, and no hardware expansion required. Simu-lation results show ERSS algorithm achievs noticeable improvement over RSSI algorithm on distance locating accuracy and responding time, and it is suitable to be applied on the environment of wireless sensor network nodes with low cost and performance of hardware.
To solve the safety issues in cloud storage services for network characteristics and data sharing characteristics,and based on the CP-ABE(cipertext policy–attribute based encryption)algorithm,a cipher text access control mechanism was proposed.According to access control and related architecture,the corresponding secure data structure algorithms were given.After this,the simulations and the performance analysis were given to evaluate our algorithm.Under the premise of untrusted service provider,the proposed mechanism can ensure the data security of the cloud storage system in an open environment,and can reduce right management complexity through property management.
In order to resolve the resources management in dynamic heterogeneous environment,a kind of task scheduling model for grid environment was proposed.The model considers the computing resources,storage resources and bandwidth resources of current virtual organization in grid,and the optimal target of the model is to achieve the max-ratio and the min-cost of the above three kinds of resources,viz to build the min-max function.To compare with GA(genetic algorithm),PSO(particle swarm optimization) was applied in solving the min-max function so that the ratio of using resources and the efficiency of scheduling task are enhanced.Meanwhile,with the rise of iterative times,the searching speed,optimization ratio and avoiding pre-maturity are also distinctly enhanced.
The spectrum sensing process was described based on WRAN.By analyzing physical connection of cognitive wireless network,the mathematical model of spectrum a location was given,and then it was converted into a constrained optimization problem,whose goal was to maximum the profit of network.An immune clone selection algorithm was proposed to solve the problem,and the algorithm convergent with probability 1 was proved.Finally,the simulation experiments were done to test the algorithm.The results showed that compared with CSGC algorithm (color-sensitive graph coloring) and GA-SA (spectrum allocation based on genetic algorithm),t is algorithm could achieve maximization of network profits.Meanwhile,the system simulation resu on WRAN confirmed its effectiveness.
To cope with the co-channel interference between cellular links and device-to-device (D2D) links concurrently transmitting with the long term evolution-advanced (LTE-A) uplink spectrum,a joint resource allocation scheme was pro-posed to maximize the global energy efficiency of D2D links.The above problem can be decomposed into the power control subproblem and the channel assignment subproblem.Specifically,the power control subproblem can be optimally solved with the help of Dinkelbach method and Lagrange duality.Based on the above results,the channel assignment subproblem turns out to be the set packing problem which was generally NP-hard problem,Therefore,a heuristic algo-rithm was further devised to achieve a tradeoff between performance and complexity.Simulations show that the proposed joint resource allocation scheme outperforms the ones where only single resource variable is optimized,and it achieves the polynomial-time complexity at only minor performance loss when compared to the global optimum.
In order to evaluate the condition of network,a new synthetically multi-metric performance evaluation method was put forward based on multiple measurement metrics and applied to the performance evaluation of links and nets.The value of calculation reflected the performance condition of links and nets.The performance change of links and nets could be analyzed according to the different strategies using the method.The results of experiment indicate that the method can evaluate the performance of links and nets effectively.
Aiming at working out the problem that fuzzy logic and neural network based access selection algorithm didn't consider the load state reasonably in heterogeneous wireless network,a RBF (radial basis function) fuzzy neural network based access selection algorithm was proposed.The algorithm executed factors reinforcement learning for the fuzzy neural network with the objective of the equal blocking probability of accessible networks to adapt for load state dynamically,and achieved the intelligent access judgment.simulation results show that the algorithm can balance the load of heterogeneous wireless networks effectively and guarantee the QoS of real time and non-real time services,as well as decrease the blocking probability compared to the maximu load balance based algorithm (MLB algorithm).
A ring based multi-hop clustering routing algorithm(RBMC) for wireless sensor networks(WSN) was proposed.The main task of RBMC was to prolong the lifetime of the network,balance energy consumption between nodes.The main idea of RBMC was to divide the WSN field into concentric rings and build unequal size of clusters in different rings.From the objective of minimum energy consumption in first ring and balance of it between first ring and other rings,the optimal choice of cluster numbers for each ring was deduced.Via adoption of different algorithms for cluster head election,RBMC could be applied to homogeneous and heterogeneous energy settings.The simulation results prove the good performance of RBMC in large area WSN scenarios.
In the complex and dynamic Grid system,failure of resources was very common.And the failure of Grid re-sources can halt the execution of tasks on them.To mitigate this problem,the concept of tasks survivability was pro-posed,a local objective function which can be adjusted was proposed by incorporating the makespan and survivability of tasks and maximizing the survivability of tasks was devised.The simulation results confirm that the scheduling algorithm can trade off these two objectives,and can satisfy different demand by adjusting the weight parameter in the objective function.So it can be applied in the complex Grid computing environment well.
In view of the current popular cloud computing technology,some security problems were analyzed.Based on BLP(Bell-LaPadula) model and Biba model,using the access control technology based on behavior to dynamic adjusting scope of subject's visit,it put forward the CCACSM ( cloud omputing access control security model).The model not only guarantees the cloud computing environment information privacy and integrity,and makes cloud computing environment with considerable flexibility and practical.At last,it gives the model's part,safety justice and realization process.
Connected dominating set based virtual backbone played a key role in a wireless ad hoc network for routing optimization,energy conservation and resource allocation.Using the concept of minimum dominating set,maximum independent set,new graph coloring theory based minimum connected dominating set algorithm was proposed to construct virtual backbone in wireless ad hoc networks.The accuracy and efficiently to generate minimum connected dominating set was analyzed and the computational complexity of the proposed algorithm was compared with that of conventional algorithm.Simulation result results show the proposed algorithm has less number of cluster heads and backbone nodes and the new algorithm can outperform in dense environment.
Based on Lyapunov stability theory and used the Lyapunov’s direct method by designing a nonlinear function in the response system to realize two different chaotic systems globally synchronized,the stability in zero of the error dynamical system of two systems was also verified.The technique of Similink based on Matlab was used for numerical simulation and the two synchronized systems were used in chaotic masking and parameter modulation secure communication.The simulation results showed that,the method realized synchronization of two chaotic systems easily and the method could be applied in the secure communication based on chaotic synchronization.
Motivated by frequency hopping for military communication,end hopping tactic was proposed which can mitigate those threats such as DoS and eavesdrop greatly by changing the end information of port,address,timeslot,cryptographic algorithm or even protocol pseudo-randomly during end to end transmission.An active defense model has been established upon end hopping.Then a test-bed has been implemented through mobile agent with a successful solution of synchronization and handoff.The model shows better performance in both theoretical analysis and empirical studies.The work demonstrates that end information hopping tactic is feasible and effective for active network confrontation.
Based on latest development of three network convergence in China,the article discuses connotation,characteristics and trends,meaning,targets,loss and gain for each party,service forms of three network convergence.Finally,the article analysis major challenges,keys to success and promotions proposals.
Colluding clique has become the first threat to trust model. However, today's trust models in P2P network are known as green hand in handling colluding cliques. CCD, a colluding clique detector, was proposed to detect the exis-tence of colluding clique by measuring similarity of peer's activities, which included a mathematical description and a distributed implementation. The simulation results show that CCD is considerably effective in detecting colluding cliques and trust model with CCD is more reliable and has higher success rate than the same trust model but without CCD espe-cially when many colluding cliques exist.
A fast adaptive inter prediction modes decision method was proposed to reduce the complexity of H.264 encoder. Firstly the candidate inter modes used in rate distortion optimization can be limited in a small mode group (MG) by using the characteristics of the motion compensated residual image. Then the two most probable modes of the chosen MG are obtained based on the modes of the up MB and the left MB. By calculating and comparing the rate distortion cost of the two modes, the optimum mode of the MB is determined. The experimental results show that the proposed method can save the encoding time up to 65% on average with ?0.24dB performance degradation that can be used in real time applications.
Automatic and accurate extraction packet signatures are the foundation of the precise traffic identification at application level.A method which can automatically extract the packet signatures of characteristic string and packet length for traffic identification at application layer was proposed.The identification rate,accuracy rate,positive identification error rate and negative identification error rate have been verified with experiment on some traces to valid the mined signatures.
Based on the analysis of the characteristic of IOT and operators' network,this article demonstrates how to construct the operational and manageable IOT structure by means of the new network element IOT gateway.This article describes the composition and technical points of IOT gateway,and illustrates the application situation of IOT gateway by examples.
A robust time-delay estimation algorithm in situations where a large amount of additive colored noise and reverberation was presented.This algorithm estimates TDE through blind identification of room impulse response in order to eliminate the effect of reverberation,and uses eigenvalue decomposition of a lagged correlated matrix to avoid the effect of colored noise.Simulation results show that the proposed algorithm can give robust time-delay estimation when colored noise and reverberation exist.
The driving of demand,technology and policy give great help of cloud computing development.In this paper,the cloud computing ecosystem of home and abroad was introduced,and analyzed business models.Finally,cloud computing trends were given.
The energy supply of nodes will be limited strictly in the wireless sensor networks (WSN).Considering the characteristic,the responsive distributed clustering algorithm (RDCA) was proposed.The nodes implementing this algo-rithm can elect cluster heads based on local topology information and decide which cluster to join based on cost function without the location information,and the algorithm rather suits for the periodical WSN.The results of analysis and simu-lation indicate that the RDCA can provide better load-balancing of cluster heads and less protocol overhead.Comparing with LEACH protocol,RDCA improves the uniformity of energy consumption so that the network lifetime was pro-longed about 40%.
Since the inception of the concept of “Internet of things”，how to promote the development of the Internet of things has received a lot of attention from various fields.From the perspective of telecom operators，in order to lead the development of Internet of things and create cross-industry，cross-region information processing centers for the Internet of things，we need to consider the adoption of cloud computing technology and the construction of a cloud platform for the operations of the Internet of things.This paper studied the requirements of constructing an operation platform for the Internet of things including the characteristics of cloud computing，based on the analysis of the system architecture of the Internet of things.Furthermore，it proposed a design and implementation strategy for developing the cloud platform supporting the operations of the Internet of things for telecom operators.
The concept,history and development of the mobile phone two-dimensional barcode were introduced firstly.The contrast between the properties of the mobile phone two-dimensional barcode and RFID leaded to the conclusion of the appropriate useful direction of the mobile phone two-dimensional barcode then.The application architecture of the mobile phone two-dimensional barcode was analyzed.Finally,this paper gave the future prospects and progress of the mobile phone two-dimensional barcode in the Internet of things.
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