- EI核心期刊
To make the agents negotiate more efficient in bilateral multi-issue negotiation in multi-agent based e-commerce, an agent negotiation model is presented,。A hybrid genetic algorithm (HGA) is applied in the model to enhance the negotiation efficiency. Experiments are done for 1000 times for four kinds of agents to gain the satisfying result, Standard Genetic Algorithm(SGA) averagely needs 218 runs negotiation , Genetic Algorithm based on Metropolis rule(MGA) averagely needs 184 runs, adaptive genetic algorithm(AGA)averagely needs 152 runs while the hybrid genetic algorithm(HGA) averagely 121 runs. Experimentals show that the HGA can gain the optimal negotiation result more efficiently than other three kinds of genetic algorithms in bilateral multi-issue negotiation.
An adaptive detection mechanism is presented to detect the label switched path (LSP) failure. Based on the adaptive LSP detection model, the network delay and thedetection timeout are measured with loopback detection. According to the delay and timeout, this mechanism adaptively adjusts the detection period and schedules thetransmission of detection packets. The failure is quickly detected with a few detection packets. Experiments show the mechanism can find failure in required time, and the detection costs are lower than the fixed period detectioncosts.
The classic MQS methods can not be applied in proximity effect analysis in high frequency. To solve the problem, a method used to analyze the proximity effect in rectangular loss transmission line is proposed and applined in full transverse electromagnetic frecuency Additionally, AC resistances are calculated to correct the parameters in telegraphist’s equation, so it is feasible to do transmission characteristics analysis in wide band. Simulations show that this method has a good precision in currents distribution and AC resistance calculation.
A detection probability based iterative localization algorithm using weighted least square is proposed to solve the secondary users' problem of locating the primary users in cognitive radio networks. the primary users' transmission modal is described as a 2-state Markov modal and ennergy detection is used by secondary users for sensing.The proposed algorithm leverages the cooperative spectrum sensing to locate the primary users and is working transparently to the primary system. Furthermore, the proposed localization algorithm is able to acquire the three-dimensional position information of the primary user. Next, a simplified version of the algorithm is introduced to reduce the complexity. We have also conducted theoretical evaluation and obtained the Cramer-Rao lower bound (CRLB) in terms of the mean square error of the algorithm. Simulationshow that the performance of the improved algorithm approaches the CRLB and is able to estimate the three-dimensional positions of the primary user effectively and promote the lcalization precision.
A hybrid switched optical network based on service plane is proposed for improving the adaptability of optical network. Service plane can choose different switch mode according with service type. Optical burst swiching(OBS )is chosen for burst and packet-oriented services;while optical circuit swiching(OCS)is chosen for the services requiring hinh bandwidth and guaranteed quality of service(Qos)Analyses and simulations show that the model is valid,and the performance of net-work can be improved
An automation extraction method for the pavement cracking with joints is propose d. It includes image preprocessing, cracking extraction algorithm based on segment connecting and joint filtering algorithm based on Hough transform. In image preprocessing, partially overlapped subblock histogramequalization (POSHE) is used to enhance the contrast of the image, it is more locally adaptive than that of the conventional histogram equalization. The binary image is obtained by a method called “localglobal matching” and high frequency emphasis. In cracking automation extraction, an automatic recognition algorithm based on connected domain correlating is proposed, it joints correlated cracking segments as one and extracts the cracking in pavement image with lots of texture noise. The result of cracking detection is finally obtained by removing joint on pavement, that is based on Hough transform. Experimental results demonstrate that the proposed cracking recognition method can accurately detect cracks on cement pavement with jint, and meets the requirements of the realtime processing..
Conformal geometric algebra (CGA) and
A hybrid cooperative relay selection algorithm (HCRSA) is presented for relay based cellular networks. According to current user density in a certain cell, when twohop transmission mechanism is adopted, HCRSA will be adapted selectively between two different cooperation schemes. These are realized either between the parallel transmission between the base station and a relay node or by adopting parallel transmission between another mobile terminal and relay node. Simulations demonstrate that, compared with fixed relay selection schemes, HCRSA can dynamically choose different cooperative strategies according to current user condition in the cell by fully utilizing cooperative communication so as to increase effectively the user capacity and as to improve system performance as well.
A positioning algorithm based on two satellites was studied in assisted Global positioning system (AGPS) in order to realize positioning efficiently in weak signal to capture satellite and to provide auxiliary data more quickly. The positioning solution was used with Marquardt algorithm in which the step factor is used and adaptively adjusts according to the change of objective function. The errors caused in solving the singular equation groups with GaussNewton algorithm can be removed using this algorithm. The mean positioning bias can be decreased from 703. 24m to 116.63m when there exist two overlapped satellites in two measures or from 108.93m to 32.17m when only one overlapped satellite, but the computation increases only a little.
SelfInteraction Effects Analysis of UltraWide Spectrum
High Power Microwave of Lower Frequency Side in Lower Ionosphere
Based on the radiowave propagation theory and high power microwave (HPM) atmosphere propagation mechanism in ionosphere, the selfinteraction effects of ultrawide spectrum HPM of lowerfrequency side are analyzed. The formulae for selfinteraction factor are obtained in the case of intense field. And the influences on selfinteraction effects caused by the electricfield intensity, the radiowave frequency, the electron collision frequency, the electron density and the propagating distance, are also discussed. Simulations show that the selfinteraction effects will appear more obviously with the increase of the amplitude of the initial field intensity, the frequency of ultrawide spectrum HPM, the density of electron density, and the propagation distance. .
Based on the grouped signals and iterative detections, both parallel and serial iterative detectors are proposed for multipleinput multipleoutput (MIMO) wireless systems. The iterative detectors use the soft information obtained from last detection to get the mean of the interference signals and the coefficients of the whitening filter. Thus the iterative detector can greatly reduce the biterror rate. Between the iterations, the random grouping algorithm can further reduce the biterror rate. Simulation shows that the maximum parallel iterative groups a posterior detector (PIGMAP) and has a good balance between the system performance and the detection delay and the complexity. So PIGMAP will be a promising choice in practice use.
Performance Analysis of Fractional Incremental Relaying Protocol in Wireless Communications
A cooperative protocol termed as fractional incremental relaying (FIR) is firstly presented to achieve higher spectral efficiency for wireless communications. In FIR protocol, when direct transmission of a packet fails, the relay node divides the received packet into several subblocks and transmits one by one as needed instead of the entire packet. Both analysis and simulation demonstrate that the proposed FIR protocol can achieve less average transmission duration and higher spectral efficiency than the traditional incremental relaying protocol does.
According to the features of intrusion tolerant system compared to ordinary network system, an evaluating the security situation special for intrusion tolerantsystem is proposed. Three evaluation indexes are included: firstly, the confidentiality of data, the integrality of data and the usability of service are proposed based on the influence of intrusion and the function of intrusion tolerance. Secondly, the ways of quantifying the indexes are given according to the features of each index, and thirdly, the security situation of intrusion tolerant system is evaluated dynamically through computing the three evaluation indexes. Experiment shows that the method is easy to be operated, and reflects the actual security status of intrusion tolerant system.
In order to reduce the limits of time synchronization and cooperation between nodes and reduce the measurement traffic in topology inference techniques based on tomography, a selfadaptive measurement method that measured delay variation and a selfadaptive topology inference algorithm based on delay variation are put forward. The feasibility and correctness of selfadaptive topology inferencealgorithm based on delay variation are analyzed. The algorithm is validated through simulations by NS2. The simulation indicates that the selfadaptive topology inference algorithm based on delay variation can infer network topology better than the topology inference based on one way delay and had little limit.
A global positioning system(GPS) Doppler frequency shift estimation method in earth centered earth fixed(ECEF) frame was proposed. A GPS Doppler model was constructed by using geometric scalar analytic approach, considering the fact that observer is not necessarily on the ground trace of the satellite. In addition to the modeling and computation of orbital angular velocity, visible window of satellite, and the maximum elevation earthcentered angle, Doppler's characterization with regard to the observing time was deduced and analyzed. Applications in real time Doppler frequency shift related parameters estimation on assisted GPS(AGPS) receiver verify the feasibility and performance of the presented method.
In peertopeer(P2P) networks, there are not trusted authorities, Trust relations between peers cannot be establish with traditional methods. A new trust model for P2P networks is described, in which trust relations between peers are set up upon reputations. Utilizing fuzzy theory, it can be customizable. Also utilizing time grouping, it presents a concrete but concise method to solve the time relativity problems. After storing the reputation information of each peer in its neighbors, it will reduce the network traffic and delay problems.
Average Outage Probability of Cooperative Communication
System in Symmetric Wireless Networks
An analytical expression of the average outage probability on symmetric cooperative wireless networks is derived with consideration of the link gain between the source and the destination. Compared with schemes with no link gain, the study shows that it will improve the outage performance. Moreover, the power allocation problem is analyzed that the power is distributed equally between relays. It shows us that the optimal power allocation ratio is subjected to the total power in networks and to the networks size.
To achieve full diversity and decrease decoding complexity, an adaptive design for quasiorthogonal spacetime block codes is proposed. Known of channel state information, the adaptive parameter can be calculated, and the input symbols can be coded in the designed structure. With the particular spacetime codes structure, symbols on different antenna are orthogonal to each other, and the received symbols can be singlesymbol decoded. Simulation shows that the adaptive scheme has obvious advantage compared with constellation rotation scheme. The limited feedback scheme is feasible and has almost the same optimal performance as the ideal full feedback scheme.
A new orthogonal frequency division multiplexing (OFDM) cyclic spectrum detection scheme is presented based on intended signature. Compared with original schemes, the proposed scheme will improve the detection performance under condition of a lower signalnoiseratio and unincreased detection duration. This scheme enhances the robust of against noise uncertainty effectively，and gets a robustly result of detecting weak signals and improves the detection performance.
A MultiPriority Algorithm with RTS MultiReservation and
To protect quality of service(QoS) of high priority data stream in wireless local area networks(WLAN), a multipriority algorithm named multiple reservation dynamic content window(MRDCW) is proposed. First, it adopts request to send(RTS) multiple reservation priority differentiating to decrease the influence to high priority data stream by low priority data load increasing, and then a mo
World wide web traffic protocols and details are analyzed with measurements. A group of quality of service (QoS) parameters of web traffic are proposed. These parameters focus on highlayer and endtoend QoS. They can reflect users' feelings when visiting websites and can also give technical details on reasons of such feelings. Concept and algorithm of each parameter are described. The relationships among each parameter, existing parameters and userfeelings are analyzed. Active measurements on practical web traffic are performed during recording these parameters. The useraware web QoS is analyzed correspondingly. Measurement shows that given parameters can reflect useraware web QoS better than existing ones.
According to the loginfinitely divisible cascades framework introduced from the analysis of turbulence scale, this thesis analyses the multiscale character of wirelesspacket network traffic gathered in mobile operations' network, sampled with general packet radio service (GPRS)， found that the actual GPRS traffic conforms to the loginfinitely divisible cascades framework; Further more aspects of analysis on wirelesspacket flow data are accomplished based on this method, found that log infinitely divisible cascades (LIDC) is very effective on analysis of wirelesspacket traffic multiscale character. The LIDC can depict the scalecharacter in the fullrange scale of traffic, as well as it can differentiate the valid range within a specific scale. And more, based on this framework, this thesis's analysis shows that the scale of wirelesspacket traffic complies with powerlaw, monoscale and scaleinvariance.
A Hierarchical Routing Algorithm in ION
The hierarchical routing infrastructure in intelligent optical network (ION) is researched. Two algorithms called dynamic hierarchical balancing routing algorithm (DHBR) and dynamic hierarchical routing algorithm based on optimized gateways (DHROG) are proposed in which the resource coordination, the balance for interdomain links and the gateway nodes are considered based on fixed alternate hierarchical routing. Simulation shows that the average block probability of the network can be reduced effectively with acceptable time performance by these algorithms.
Based on the analysis of the signal model in code division multiple access (CDMA )system, a multiuser detection algorithm based on blind source speration (BSS) is proposed. The algorithm made full use of the independency of the user's information. Simulations show that, with the same signaltonoise ratio, the symbol error ratio (SER) of the proposed is about half of that of the minimummeansquare error (MMSE) algorithm. When the power ratio of the interference user to the expected user (orinterferencetosignal ration, ISR) is 40?dB, the SER of the algorithm is two order lower than that of the MMSE algorithm. Furthermore, the higher ISR is, the greater the degree of improvement of the ability of antinear far effect in the new algorithm.
A perfect concurrent signature protocol proposed by Huang et al in 2007 is analyzed. Two attacks are given out to show that there are two weaknesses in Huang's protocol: firstly, both participators A and B can change the signed messages after the concurrent signature protocol is completed; secondly, both A and B can forge a concurrent signature themselves. To prevent such forgery attacks, an improved protocol is proposed by adding authentication to the keystone information, and then the security of the improvement is analyzed.
An algorithm is proposed for scheduling different types of services and for improving bandwidth utilization of links in transport multiprotocol label switching network. This algorithm is implemented in a simulation testbed based on OPNET modeler for performance evaluation. Simulation is shown that, compared with traditional scheduling algorithms, the complexity of this algorithm is notincreased. And a better timedelay performance of the high class services is also verified.
The resource allocation model for downlink multiuser power communication orthogonal frequency division multiple access spatial division multiple access (OFDMASDMA) system is studied with the restrictions of requirement bit number for each user and power upper limit as well as specifically bit number for every subchannel in every orthogonal frequency division multiple (OFDM) symbol. An algorithm for power adaptation resource dynamic allocation with bitloading seeking table and exchanging adjustment is proposed based on user spatial orthogonality and priority. Simulation shows the proposed algorithms in power special wireless communication environment, and indicates that the proposal improves spectral efficiency significantly while maintaining quality of service guarantees and certain fairness.