- EI核心期刊
A new class of loose synchronous（LS）spreading codes with zero correlation window (ZCW) was presented. It was constructed by making Kronecker product of orthogonal matrix and ZCW complementary codes. This new LS code increases the number of perfect complementary pair, and extends ZCW within the same group. Moreover, both auto-correlation and cross-correlation of ZCW in the same group remain identical. The minimum ZCW among different groups is the same as that of basic LS codes. The method for constructing these new codes is presented and the ZCW properties are also verified. The number of these new codes is only smaller than theoretical upper bound by one.
A novel approach using density pointer is proposed to initialize cluster centers. The density pointer (DP) algorithm takes the geometric centers of grid cells as symmetrical centers. With the interconnections between these centers and the vertices of grid cells, DP partitions traditional rectangular-like grid cells into hyper triangle-like subspaces. The density differences between hyper-triangle subspaces and the corresponding subspaces of their neighborhoods are considered to define density pointers. After that, DP detects density pointers to calculate the aggregation factors of dense cells and then takes the gravity centers of the cells with larger local aggregation factors as initial cluster centers. Experiments on both public and real datasets show that DP is helpful to find cluster centers near to real centers quickly and effectively. Moreover, the running time of DP is linear with respect to the number of instances, the number of grid cells and the dimensions.
The problem of a spherical rolling robot’s climbing capability is analyzed and the related climbing experiment is introduced. A method of phase plane is used to investigate the movement of the spherical rolling robot before jumping and its jumping condition is developed. The dynamic model of the spherical rolling robot after jumping is derived using the D’Alembet principle. Simulation and the experiment have demonstrated good feasibility and validity of the theoretical analysis for the spherical rolling robot both in climbing and jumping.
Electric field expression has been figured out, by mean of Green functions, to simulate the field distribution in the planar model for source-stirred reverberation chamber (SSRC), and then helps to analyze two influence factors. The simulation results show that the better performance with smaller quality factor（Q ）and boarder source moving range, and all these conclusions are obtained from viewpoints of the field uniformity and the probability density function (PDF).
Time division duplex - code division multiple access（TDD/CDMA）system can flexibly allocate uplink and downlink to be adapted to the asymmetrical service in theory. However, diversified switching point will produce the inter-cell interference at crossed slot. In this paper, a new scheme is proposed which can be used to resolve the problem of inter-mobile station (MS) interference at crossed slot by setting the separate area. The separate area is determined by the difference of pilot signal received by the mobiles in the new scheme. Further more, the separate area is smaller than that in other schemes, so the coverage at crossed slot increases. The inter-base station (BS) interference at crossed slot is also analyzed in this paper. The numerical results illustrate that the inter-BS interference is much stronger due to the better transmission environment and the mobile system hardly resists the inter-BS interference. Therefore, it is difficult for the technology of diversified switching point to be applied in practical TDD/CDMA system, such as time division-synchronous code division multiple access (TD-SCDMA).
The work addresses the problem of cheating prevention in secret sharing. For any integer , strictly - cheating immune secret sharing scheme under the unconditionally secure is given. It is concluded that the defining function of strictly secret sharing scheme is -resilient and also is -strengthened propagation criterion. Furthermore, its degree is high. So it has better cryptographic properties than that of the known results.
Making full of multi-polling technique and the silence characteristic of voice over IP（VoIP）service, an new efficient uplink scheduling algorithm is proposed based on broadband wireless access system. via analysis of theory and simulation, the proposed algorithm has superior performance in view of throughput and capacity on the condition of having no influence in the access delay of VoIP service.
Two algorithms are proposed against single span failure in WDM networks. One is called link-based optimized shared-protection algorithm (LB-OSPM). The other is Hamiltonian preconfigured cycle （p-cycle） based protection algorithm (HPC). LB-OSPM introduces wavelength usage matrix and wavelength reservation matrix to record the detailed usage of wavelengths reserved in the past so as to allow different protection paths of working trees to share reserved wavelengths. HPC takes advantages of single Hamiltonian p-cycle to cover all working links in the network to attain source efficiency and fast protection. Study uses the topology of COST239 to calculate the network blocking probability of these two algorithms under various conditions of wavelength resources and network loads and compares them with an existing cost-effective algorithm, optimal path-pair-based shared disjoint paths algorithm（OPP-SDP）. The results demonstrate that our algorithms can gain lower blocking probability while assuring a 100% restorability rate in the case of single span failure.
In view of the deficiencies of timing consuming and complex analyses in the integration testing to complex software, a model of software testing optimization based on component-dependency is presented. Firstly, it analyzes and describes the complex component-dependency, classifies the components using the dependency relation between components, and assigns the different priority to different component set. Classifying the components for testing can achieve allocating testing resources reasonably. Finally an experimental result and performance analyses is given.
A bidirectional protocol of probabilistic teleportation on the clients/server model is proposed, leading to the maximal probability of successful teleportation. It is proved that the partially entangled quantum channel by the Schmidt decomposition is transparent to the clients. To perform probabilistic teleportation via the generally entangled quantum channel, the clients must know a unitary operator that transforms the quantum channel into the clients’ transparent quantum channel.
One of the main Reasons of fault growing is wrong routing configuration that R5 will be resulted from conflicted routing in the Internet routing system, especially between heterogeneous routing protocols. A new approach to modeling heterogeneous routing system and analyzing conflicted routing is proposed. It employs the language of tempora1 ordering specification(LOTOS in short) as description language, and by suitable specifying and developing some constants and operations an algebraic model system is constructed. By deducing the algebraic model the conflicted routing can be found out efficiently. In order to support our viewpoint an experiment is carried out that employs scalable simulation framework (SSFnet in short) to simulate behaviors of the border gateway protocol (BGP4 in short) and the open short path first (OSPF in short）. The experiment result shows the consistency.
Based on the field strength simulation calculation and maximum usable frequency (MUF) prediction on the short-wave (HF) when propagating through ionosphere E or F2, selections of deployment position, operation time and emission frequency for the vehicle mobile HF transmitter to obtain the maximum field strength at the scheduled receiving spot are proposed when considering the reflection of HF by ionosphere E or F2. Rationality of the simulation model is proved through the comparison between software simulation prediction and test data, which will provide more reasonable assistant decision-making suggestion for the deployment scheme of HF transmitter.
Two integer linear programming （ILP） models based on source formulation are developed to effectively address waveband switching（WBS）-related problems, which include the optimization of networks with multigranular optical crossconnects（OXCs） and networks with additional constraint that all wavebands can only contain lightpaths with the same destination. The topology of NSFNET is employed to compare he numbers of variables and constraints of the source-formulation ILP and link-formulation ILP in current research. The study of the comparison on the complexity shows that the computing complexity is significantly reduced by the model based on source-formulation ILP because of the reason that the model only considers the resource utility of the source node. As a result, the source-formulation ILP can be applied to the optimum solution of the optimization calculation, and used to evaluate the effectiveness of optimization algorithm which will debase the optimization target to reduce the calculation cost.
In order to avoid the collision occurs when many transponders send the recognition information to the reader in radio frequency identification; identification (RFID) system at one time, compositor algorithm based on identification（ID）operating to timeslot number is proposed. This algorithm gets the sent bits in corresponding timeslots of the competitive frame for all transponders by the operating result of transponders’ identifications to the timeslot number of competitive frame. So it can confirm the sending order of all transponders in the whole data-sending period by the filled competitive frame and distribute different sending orders to different transponders. The computer simulation shows the new algorithm is effective to solve the problem of anti-collision for multi-target recognition in RFID system and effective to the situation that there are many transponders.
Based on decoding performance, complexity and latency of finite-geometry low-density parity-check (FG-LDPC) codes, an efficient decoding algorithm was proposed. The new algorithm is a hybrid bit-flipping (BF)/majority-logic (MLG) decoding scheme. In BF decoding, an efficient method was explored to measure the reliability of the checks. At the completion of a small number of iterations, the output from BF decoding is decoded by MLG decoding. In the hybrid algorithm, there are no float operations. Simulation results show that the hybrid algorithm can provide 0.3 dB coding gain over weight bit-flipping (WBF) decoding.
In order to utilize the available frequencies efficiently in cellular mobile communication network, a frequency assignment method based on microcanonical annealing algorithm was proposed. In this approach, the optimal frequency deployment was achieved by random walks of demon in the state space when the potential interference was defined as an energy function. Simulations show that if available frequencies are sufficient, the proposed algorithm can achieve equivalent results compared with simulated annealing algorithm. However when available frequencies are reduced, this new heuristic algorithm offers better results with higher probability to hit the global optimum at the cost of less function evaluations. In addition, its fast convergence is also demonstrated by typical optimization tracks.
Network selection problem in wireless local area network(WLAN) and universal mobile telecommunications system(UMTS) integrated network was studied using fuzzy analytic hierarchy process. A novel network selection algorithm that combines analytic hierarchy process and fuzzy comprehensive evaluation was proposed. By analyzing the factors that influence network selection in integrated systems, a network selection decision-making model was founded and the weights of these factors were calculated. A method for calculating relative-membership grade was proposed by analysis of fuzzy comprehensive evaluation model. Total membership grade was calculated through relative-membership grade and the weights of these factors. The optimum network was selected according to total membership grade. The validity and accuracy of the algorithm was confirmed by the simulation.
It is investigated the confidence probability of Monte Carlo (MC) simulation results of system bit error rate (BER), under condition of single-path Rayleigh fading channels and data modulated in binary phase shift key（BPSK）. Firstly, some principles and conclusions of traditional MC methods are put forward. And extended these conclusions to more general conditions. Secondly, the numerical relations among the max relative error of the simulation results,the signal to noise ratio, ratio of the data rate to the Doppler shift, And the fading cycles under certain confidence probability based on the characteristics of Rayleigh fading channels are deduced. The simulation number can be deduced by this numerical relation. It is also indicated in graphs under typical simulations for reference of engineering practice. All conclusions are demonstrated by computer simulations.
The problems of combining multi protocol label switching （MPLS） with multicast were studied. Based on the receiver data-driven label distribution, a new mechanism was proposed about how to construct a label switched path （LSP）multicast routing tree in the MPLS domain. The joining, pruning and multicast packets forwarding algorithms were presented. In addition, the MPLS module of network simulator was modified for the MPLS multicast simulation. Analysis of performance and simulation results show that, comparing with traditional multicast, MPLS multicast can take advantage of the fast forwarding feature of MPLS to reduce the packet-delay from source to destination effectively.
In a protocol conformance testing system specified in the extended finite state machine (EFSM) model, a novel method of executable state identification sequences (ESIS) generation is introduced to preferably solve the executability problem of state identification sequences (SIS). The approach, from the aspect of state identification demand and the EFSM configure projection subspace, adopts fractional-step computation to generate the shortest ESIS in the specific identification scene through searching a executability analysis tree (EAT) in bread-first-search way. As a result, the complexity of computing all state identification sequences using single-step method in the whole state configure space is reduced. The experiment results show that the proposed algorithm is effective to generate executable state identification sequences in EFSM model.
In order to get proper deployment locations for hot grid services in pursuit of the shortest average response time for clients, an algorithm based on election and region combination was proposed. The distribution and access frequency of clients, network delay and the process performance of grid nodes were considered. During the initial phase, the topology of grid is divided into multiple regions, then one of these regions is eliminated through election, and the remains are readjusted. After several iterations, the deployment locations are found out. Simulations show that the algorithm can get optimal resolution approximately.
A four-tied Internet protocol television（IPTV） quality of service （QoS） implementing architecture is presented in wireless environment. By collaborating compression encoding, content distribution network(CDN), multicast, peer-to-peer (（P2P）, cache, reshape, etc, in dynamic and bursting IP traffic environment, end-to-end QoS transport for user IP TV service application will be assured . Simulation result shows that, by rationally provisioning and adapting, it can provide the bandwidth required by standard-definition TV (SDTV) in real internet.
A host usually changes its network traffic characteristics when infected by a worm. From the observation, a worm detection method was proposed. It drew inspiration from the negative selection of the immune system. Firstly, V-detector algorithm—a real-valued negative selection algorithm with variable-coverage detectors was improved. The improved algorithm endeavored to generate large detectors according to the non-self space distribution. Compared with V-detector, the improved algorithm generated a much smaller detector set and increased the detection efficiency. Secondly, the improved V-detector algorithm was used to generate detector sets and monitor hosts’ network traffic characteristics for worm attacks. Experiments show that the method is effective to detect traditional worms as well as multi-vector polymorphic worms.
For beneficial of log likelihood ratio decoding of low-density parity-check (LDPC) coded modulation, an adaptive power allocation algorithm is proposed in orthogonal frequency division multiplexing (OFDM) systems. The transmit power allocated to sub-carriers is adjusted according to the channel gain of each sub-channel to optimize the decoding performance. Simulation results show that the algorithm can effectively improve the bit-error-rate performance of the system, adapting to the time-variant behavior of the multi-path fading channel.
Based on the introduction of qiality of experience (QoE) and key performance index (KPI), a measurable QoE evaluation algorithm for Internet differentiated service is proposed. Its implementation scenario that can measure and evaluate users’ QoE is described. The important roles of QoE, used as a quantitative specification of perceptive quality of service (QoS) for service users, for service provider to improve their QoS base on this scenario are also analyzed.
To overcome the high computational complexity problem of per-survivor-processing（PSP） algorithm in maximum likelihood sequence detection(MLSD) method and the real time channel tracking problem for fast Rayleigh fading channel, a reduced-state sequence estimation (RSSE) with per-survivor processing for Viterbi algorithm and reduced complexity Kalman channel tracking technique is studied in maximum likelihood sequence detection receiver. Computer simulation results show that the computational complexity of this simplified Kalman-RSSE-PSP Maximum likelihood sequence detection receiver is less than recursive least square (RLS) -RSSE-PSP MLSD receiver, meanwhile its bit error rate performance is lower than RLS-RSSE-PSP MLSD receiver.
The prevention of multi networm is an urgent problem in network security field. Based on the analysis of the existed vaccine technologies and peer-to-peer (P2P) technologies, an intelligent vaccine based on P2P is given. Firstly, the intelligent vaccine could transform itself with different hole, and prevent or kill multi networm. Secondly, because of its communication based on P2P, the problem of communication after firewall, and made the vaccine more effective is solved statistically.
Analytically modeling the behavior of Web service based telecomm gateway is investigated. A model based on a closed queuing network was proposed. In such a proportion there include several characteristics such as finite-sources, multi-classes services and session-based requests. Further, an M/G/1/K/H PS(C) queue model was used to simplify it. The model could be used in system bottleneck identification, performance prediction, and application configuration and some metrics are evaluated for improving the performance of the system. A Web service based telecom gateway was implemented in our project, and experimental results indicate that models faithfully capture the performance of the gateway.
The definition of adjacent matrix was extended in order to effectively enumerate all minimal cut-set of a terminal network. And a matrix decomposition algorithm was then proposed. The algorithm is based on recursive matrix decomposition and reduction. The theoretical rationale and operational rules are given. The judgment principles and reduction rules about redundant nodes and isomorphic graphs are presented. The examples given show correctness and applicability of the algorithm.
The long time-delay of mobile IP(MIP) mobile handover proposal based analysis to hierarchical MIPV6（HMIPV6）system is proposed to reduce the time-delay of MIP handover. The using of root mobility anchor point（MAP）keeps the advantages of MIP handover in hierarchical field, moreover, the adding of lower MAP avoids the influence by the failure of center node in centralized network. Through improving network layer（L3）fast handover mechanism, root mobility anchor point （RM）-MIPV6 proposal can achieve the optimal performance.
A scheduling algorithm is proposed for cdma2000 forward packet scheduling. In the conventional proportional fairness algorithm, fairness objective is achieved through the fairness exponent . is difficult to be optimized for the optimal value depends on many practical factors. In the proposed algorithm, the fairness objective is achieved by monitoring the real-time fairness of the maximum carrier to interferencescheduler. Hence we may achieve the maximal throughput while keeping the fairness criterion not violated. Simulation results indicate that the proposed algorithm has a similar system throughput to the conventional proportional fairness algorithm with optimized fairness exponent .