- EI核心期刊
Based on pricing and game theory of economics, a novel network resource allocation scheme was put forward. The centralized and decentralized models were set up. A dual gradientprojection algorithm was presented to achieve Nash bargaining solution. Network Simulation was addressed to illustrate the dynamics and convergences of this algorithm in resource allocation.
A proportionalintegralrate (PIR) controller for active queue management (AQM) scheme based on the linearized AQM model was proposed. PIR controller is well suited to dynamic network environments where traffics change frequently. In order to address the slow response of PI controller, a normalized input rate control PIR controller was used to speed up the responsive time under varying network conditions. Analysis and simulation results show that under varying network conditions PIR controller will have a fast response and improve the buffer utilization, and have a good perform in stability and link utilization.
A new blind equalization algorithm based on eigenvector algorithm(EVA) was presented to solve the phase rotation problem by employing metric including phase information of the channel, and a comparison between new algorithm and EVA was also made. Simulation results show that the proposed algorithm will increase convergence rate by 10%, improve antinoise capability by 1?dB, and compress residual intersymbol interference(ISI) by 10% without increasing computational complexity with respect to EVA as well.
Density control is the common way to improve the network lifetime of large scale wireless sensor network. Many density control algorithms are based on 0～1 coverage model, whereas probability coverage model defines network coverage ability more accurately than 0～1 coverage model in real applications. A density control algorithm based on probability coverage model was presented, which can turn offredundant sensor nodes to reduce total network energy consumption and ensure adequate network coverage ability.
A numerical model is founded to analyze the performance of two sampling modes for polarization degree as controlling signal with various polarization mode dispersion compensators in 40?Gbit/s optical fiber communication. numerical simulation results including the compensated bit error rate(BER)and polarization degree of 1000 sampling points show that when single state of polarization sampling mode is used in two stages and three stages polarization mode dispersion (PMD) compensator with more than four degrees of freedom, the numbers of degree of freedom for the compensators should not be more than four, otherwise, the compensation algorithm will be plunged in local maximum to cause severe PMD that increase bit error. So, another sampling method is proposed to be suit for three section PMD compensator, in which shortest axis lengths of degree of polarization (DOP)ellipsoid is used as the feedback signals. The performance of DOP ellipsoid is evaluated by means of numerical simulations with threesection compensator, which is better than that of single state of polarization sampling mode.
The new fault tolerant onboard computer(OBC) with dual processing modules is presented to improve the microsatellite data handling. Each processing module is composed of 32bit ARM processor. Using the fault tolerance method, The OBC's hardware structure is implemented based on commercialoffthe shelf (COTS) devices. As well as, a detail analysis of the fault handling mechanism and the software architecture is given. Considering the demanding of the extremely tight constraints on mass, volume, power consumption and space environmental conditions, the new fault tolerant onboard computer's data handling is enough to meet the mIcro satellite missions.
Congestion control is one of the cornerstones of Internet. The classical transmission control protocol (TCP) congestion control scheme, Reno, and the other two, Vegas and Fast, recently suggested upgrades for highspeed networks, are analyzed. In the comparative work, Fast's high performance is validated and its weakness, the difficulty in setting parameters, is revealed. Also, to facilitate Fast parameter setup, a measurementbased improvement is proposed. The essential idea is to introduce a macroscopic guidance layer upon end systems which will guide them to appropriate settings of number of extra packets according to periodical performance measurement on network backbone. Simulation results indicate that by realizing the target of having the bottleneck queue tend to be a fixed length, the improved Fast scheme can get a higher and steadier power, and its power will not decrease when new connections join in.
In order to effectively support the analysis and estimation on validity and credibility of the federation simulation system, which is based on high level architecture (HLA, high level architecture), and provide comprehensive assistance to aseries of decisionmarking processes based on simulations result, a federation integrated testing platform (FITP, federation integrated test platform) was designedand implemented when considering the testing requirements in the life cycle of HLAbased federation simulation system. The federation integrated testing process model was presented, and the architecture and prime components of FITP were described. Furthermore, the key techniques in the process of development were studied in detail. It proves that FITP not only provides comprehensive support for testing activities through the whole process of developing HLAbased federation simulation system, but also evidently improves test efficiency and test objectivity.
Based on studying the motion estimation of multiblock mode and multireference frame, a novel fast search algorithm was presented in H.264. The algorithm judges the skip mode, which can reduce a lot of calculation and time. It selects the block mode according to the cost function of different motion search modes. At the same time, it decides the available reference frame used in the motion search. The experiment result shows that the proposed algorithm can decrease the search calculation and greatly improve the coding speed, while the peak signal noise ration (PSNR) of picture and bit rate change very little.
A set of key performance indicator of UMTS terrestrial radio access network (UTRAN) running quality was presented to evaluate the running quality of 3G UTRAN. Meanwhile, an evaluating model based on BP neural network was proposed to evaluate the 3G UTRAN running quality. The fuzzy evaluating method was used to construct training data. It is resulted by the fuzzy evaluating method, that the model will be able to evaluate the UTRAN running quality very well.
A timed automata model of mobile Internet protocol version 6 (IPv6) using formalmethod was presented, and the protocol's key properties of liveness, mobility and seamless handoff were verified by the realtime model checker Uppaal. The verification proves that the packet loss occurs during the period of handoff process. An ideal condition guaranteeing the seamless handoff is proposed by analyzing the reason of packet loss, and in this condition, the verification shows that the property of seamless handoff of mobile IPv6 is satisfied. Some suggestions that are likely to lead to mobility performance improvement for mobile IPv6 are given.
In order to provide incentive to cooperate for nodes in Ad hoc networks, the incentive to cooperate with each other and to motivate those nodes to reveal their cost of participating in network responsibilities, the destinationdriven Vickrey auction was designed forthe motivation of the cooperation among nodes in Ad hoc networks, which would take advantage of the merit of Vickrey auctions. Meanwhile, the incurred cost of nodes for forwarding packets was taken into account explicitly. The costeffective path was determined through the series of auctions carried out by intermediate nodes in path from destination to source. Theoretic analysis proves that thismechanism can motivate nodes reveal forwarding cost truthfully, and can achieve the objective of cost efficiency in routing selection.
In order to reduce the overhead of networks, a new routing method, in which the nodes update the link states via using the frames transmitted by way of broadcasting in media access control layer, was proposed. Theoretical analysis shows that the proposed method can reduce the amount of the control packets and the probability of the occurrence of congestion, and then it can increase the throughput of the network. Furthermore, simulation result proves that the new method will significantly reduce the overhead.
Based on the instantaneous or the statistical channel state information, the channel capacity of a twohop relaying system was analyzed according to the different relaying methods. Taking the system capacity as the optimization criterion, an optimal power allocation scheme was proposed to distribute a certain power between the transmitter and the relay station. The numerical results show that, when compared with the uniform power allocation, the optimal power allocation can daptively adjust each hop power based on the different channel conditions, and can utilize the resources efficiently to further improve the system capacity.
To utilize the properties of ultrawide bandwidth, the structure of ultrawide bandwidth digital radio on fiber system was modified, and the system model was illustrated. Simulations and theoretical analysis show that different time hopping sequences (THS) will cause different system performance (signal to noise ratio), and different active number of users will bring about different average interference of time slot with the same THS. And also show that the modification will decrease the system complexity, and meanwhile, will increase the efficiency of fiber, and improve the system performance as well.
To extend the range of the sampling frequency, a method of periodically nonuniform bandpass sampling was put forward in which the value of the average sampling frequency was equal to that of the uniform sampling frequency without distortion. The spectrum aliasing was analyzed. And on the basis of the analysis, the conditions of the Fourier images of interpolants were given in the recovery of bandpass signal without distortion. The simulation example was presented to illustrate the calculation of interpolants and the reconstruction of bandpass signal from the nonuniform samples.
ecurity evaluation is an important approach for the security risk management of the information system. But there are lack of effective methods and tools for security evaluation. To resolve the problem, an object model of security evaluation is established based on the object oriented technology. The concepts of correlation test and dependency test are introduced and a set of tools is also developed according to the model. The practical application indicates that the object oriented technology can improve the efficiency of security evaluation, and the correlation test and dependency test also improve the penetration testing effects.
To improve the efficiency of quantum secret sharing, a protocol share the message directly among the users was proposed. The scheme made full use of entanglement swapping of Bell states and local operations. For detection of eavesdropping, the EPR pairs were divided into two parts: the checking parts and the encoding parts. After insuring the security of the quantum channel by measuring the checking particles in conjugate bases, the sender encoded her bits via the local unitary operations on the encoding parts. Investigation shows that the protocol is secure and two Bell states can be used to share two bits message.
The traffic balance based on Genetic Algorithm in the MPLS network was discussed. With guaranteeing the optimizing performance of the algorithm, the optimized o bjects was selected according to the network congestion analysis, which would reduce the solution space and decrease the algorithm complexity. As well as ensuring the diversity of species, the creation of the initial population was optimized based on a certain probability distribution according to the traffic distribution feature, which would enhance the algorithm convergence speed. The simulation and analysis show that the proposed algorithm can be implemented in an easy way with little effect on the routing protocol, and achieve an obviously optimized outcome with a high convergence velocity.
Cheating immune secret sharing in the unconditionally secure case was investigated. Secret sharing is a kcheating immune if any k cheaters are not better off than a participant which follows the protocol honestly. kcheating immune secret sharing scheme under the unconditionally secure would be given. The obtained function of the secret sharing scheme is kresilient and satisfies kstrengthened propagation criterion. Furthermore, its degree is high. So it has better cryptographic properties than that of the known results.
By contrasting the original video and the proceeded video, and on the base of peaksignaltonoise ratio the traditional video quality measurement, we improve the algorithm of the critical merits such as blurring and blocking, and state the preprocess. Practice proved it can map with mean opinion score of subjective video quality evaluation. So the algorithm can apply for assessing and optimizing the code device.
In order to acquire high speed switching and guarantee quality of service simultaneously, a new combined input and crosspointqueued switch is given. Based on theoretical analyzing, we show each port with a duplicated number of two is sufficient to mimic outputqueued switch, which can solve the problem between switching line rate and quality of service.
To overcome the limitations of Parlay web services, such as inextensible, a new Parlay/OSA service architecture based on open grid services architecture(OGSA), named Parlay grid services, was proposed, with which, Parlay was integrated with OGSA to provide the interfaces through web service, which inherits those advantages from OGSA, web services and Parlay/OSA, and support asynchronous operations、lifetime management、stateful service and multilayer service integration, as well as excellent extensibility. In the final, the services convergence based on new Parlay grid services architecture in next generation network environment was discussed.
Several statistics of the image graylevel comatrix and graylevel comatrix were first theoretically analyzed. Then a novel Cmean clustering algorithm, which is based on the graylevel comatrix and can be used for synthetic aperture radar (SAR) image classification, was proposed. The characteristics of different statistics were obtained from experiments. The analysis shows that the entropy, variance, the contrast and mean error will perform better. It is shown that when the statistics, which will maximize the betweenclass scatter and minimize the withinclass scatter, is adopted for classification, a much higher performance is achieved.
A novel intrusion detection method based on clonal selection algorithm (CSA)based unsupervised fuzzy clustering algorithm was presented for solving the problem of fuzzy kmeans algorithm which is much more sensitive to the initialization and is easy to fall intolocal optimization. With the method, the global optimal clustering with clonal operator which combines the evolutionary search, the global search, the stochastic search and the local search could be quickly obtained, in the mean time, the abnormal network behavior patterns with fuzzy detection algorithm could be detected. The benefit of this algorithm is that it does not need the labeled trainingdata sets and it could detect unknown intrusion. Simulation results show that the method mentioned above will be able to detect unknown intrusions with lower false positive rate and higher detection rate.
An adaptive transmitting optimization beamforming space time block codingorthogonal frequency division multiplex (STB〖JP9〗C-〖JP〗OFDM) [JP2]system, called adaptive beamfo rming STB〖JP9〗C-〖JP〗OFDM (AB〖JP9〗F-〖JP〗STB〖JP9〗C-〖JP〗OFDM) system based on channel state information (CSI), was proposed. And the optimization beamforming weight vector was derived in case of maximal receiver signaltonoise ratio. The performance of AB〖JP9〗F-〖JP〗STB〖JP9〗C-〖JP〗OFDM system when there are channel estimation errors w as given. Performance and computer simulation results of the system over wireless Reyleigh fading channels show that all the diversity resource can explored by the system, and the performance of the system can be improved significantly when compared with STB〖JP9〗C-〖JP〗OFDM, spacetime trellis codin〖JP9〗g-〖JP〗OFDM（STT〖JP9〗C-〖JP〗OFDM） and trellis code modulatio〖JP9〗n-〖JP〗STB〖JP9〗C-〖JP〗OFDM (TC〖JP9〗M-〖JP〗STB〖JP9〗C-〖JP〗OFDM) system.