最新刊期
卷 38 ， 期 10 ， 2010
- 摘要：Cyclic Prefix (CP) is inserted between Orthogonal Frequency Division Multiplexing (OFDM) transmitted blocks to combat multipath,provided that the channel delay spread is shorter than the length of CP.If this condition is not met,an additional Channel Shortening Equalizer (CSE) is required to shorten the channel to the desired length.A novel CSE for a wireless OFDM system is proposed.The CSE takes advantage of the characteristic of a wireless channel,which represents as an all zero system,and eliminates the zeros to effectively reduce the length of channel impulse response.Using feedback filters with low complexity to implement the CSE,the proposed equalizer simplifies OFDM wireless receiver.The Simulation results show the validity of the proposed equalizer.关键词：wireless communication;orthogonal frequency division multiplexing (OFDM);multipath channels;time-domain equalizer;channel shortening0|2|1更新时间：2025-07-02
- 摘要：The joint optimal power allocation (PA) problem is investigated for the MIMO system enhanced by relay in this paper.Firstly,based on the maximization of the capacity,a cost function is formulated for the joint PA optimization,where the cost function thus obtained is proved to be only convex with respect to the partial parameters but not convex with respect to the whole parameter.Secondly,a modified cost function is obtained by derived a tight lower bound of the capacity,and thus the original nonconvex problem is converted into a convex problem.Finally,a global optimum is obtained by using the convex optimization methods for the joint power allocation problem.It is confirmed through computer simulations that the proposed PA scheme outperforms the existing method in terms of the capacity.关键词：multiple-input multiple-output (MIMO);relay;power allocation;convex optimization0|2|3更新时间：2025-07-02
- 摘要：In order to reduce the computational complexity,this paper adopts Hammerstein model and Wiener model,instead of the Volterra series model,to approach a non-linear system.Furthermore,based on Hammerstein model and Wiener model,a nonlinear transmission system model is also proposed.To this new model,three non-linear algorithms,i.e.Nonlinear Channel Recursive Least Squares (NCRLS) algorithm,Nonlinear Channel Kalman (NCKalman) algorithm and Nonlinear Channel Recursive Prediction Error Method (NCRPEM) algorithm,are derived.Also comparisons on performance among these three algorithms are presented.Results of simulations show that,if residual mean square error is concerned,NCKalman performs over NCRPEM and NCRLS is the worst,while NCRPEM is the best,and NCRLS performs over NCKalman if the speed of iterative convergence is considered.关键词：nonlinear channel;Hammerstein model;Wiener model;RLS algorithm;Kalman algorithm;RPEM algorithm1|2|5更新时间：2025-07-02
- 摘要：An approach based on multi-scale chirplet sparse signal decomposition is proposed to separate the multicomponent polynomial phase signals,and estimate the instantaneous frequency of polynomial phase signal component.This method projects the multicomponent polynomial phase signals onto the multi-scale chirplet base functions.Through the different support regions of time in which the projection coefficient is the largest,this method can separate the polynomial phase signal component with the largest energy from the multicomponent polynomial phase signals. The frequency curve which connects the basic functions is the estimation of instantaneous frequency of the separated polynomial phase signal component.Simulation example show that this method can separate the components of the Multicomponent Polynomial phase signals in Low Signal-to-Noise Ratio Condition effectively,and estimate the instantaneous frequency accurately.关键词：multi-scale chirplet base function;multicomponent polynomial phase signals;instantaneous frequency;signal-to-noise ratio0|2|7更新时间：2025-07-02
- 摘要：Based on analyzing the principles of meteor burst communications and the physical characteristics of meteor burst channel,according to the mechanism of using the signal frame as the basic transmission unit for adaptive variable rate transmission,the effects of the frame length on system performance are analyzed in this paper.According to the line electron density distribution of meteor bursts,the probability density function of the initial signal power received from the trails is derived.In terms of the function of the received signal power,the relationship between the system throughput and the frame length is built and the principle of frame length selection is determined.The simulation results show that the optimized frame length can maximize the average throughput of the system and make the best use of the meteor burst channel,while satisfying the reliability and instantaneity of the meteor burst communication system.关键词：meteor burst communication(MBC);adaptive variable rate;channel decay constant;structure of data frame;probability density function(PDF)1|2|1更新时间：2025-07-02
- 摘要：Singular Vector Decomposition (SVD) has been used in signal processing,image computing,information security,and etc.In order to improve the performance of SVD,proposed a gamma:1 computing model to reuse matrix data to increase data load balance and decrease data communication;and a multi-core based parallelized computing model is given to increase the performance and expendability.At last,a prototype on a multi-core processor was implemented.The result demonstrates the accuracy of the proposed algorithm and the powerful computing ability of singular vector decomposition.关键词：data mining;document clustering;singular vector decomposition;matrix computing0|2|13更新时间：2025-07-02
- 摘要：A fast rate fault detection method for a class of multirate sampled systems with stochastic disturbance is proposed.Firstly,with the aid of lifting and elementary transformation techniques,the original system is converted into a linear time-invariant (LTI) slow rate one satisfying causality constraint.Then a slow rate steady-state residual generator is designed based on the Kalman filter.Meanwhile,based on the idea of sequential filtering,a fast rate fault detection scheme consisting of a fast rate steady-state residual generation and the corresponding residual evaluation,which can avoid the troublesome causality constraint,is further developed to overcome the drawback to the above slow rate residual generator that it has a poor real time on fault detection.The auto-correlation of measurement noises and the cross-correlation of measurement noises and process noise increased in the new systems are also considered.Finally,simulation results illustrate the effectiveness of the proposed method.关键词：fault detection;fast rate;multirate sampling;Kalman filter0|2|1更新时间：2025-07-02
- 摘要：A detection algorithm for the spatially distributed target on the background of K distribution clutter is proposed.The proposed algorithm estimates the parameters of the clutter by Expectation Maximization(EM) method and improves the estimation precision.Then combined with Goodness-Of-Fit(GOF) test ,it efficiently utilize the disturbance of target echo to clutter background.Furthermore,Constant False Alarm Rate (CFAR) property with respect to the unknown clutter power is proved.Finally,experimental results for simulated data and measured data illustrate that the proposed algorithm achieves a visible performance improvement comparing with conventional non-coherent integration and Scatter Density Dependent Generalized Likelihood Rate Test (SDD-GLRT).关键词：distributed target detection;K distribution clutter;expectation maximization(EM);goodness-of-fit test (GOF)0|2|5更新时间：2025-07-02
- 摘要：The paper studies spaceborne digital beamforming (DBF) MIMO-SAR system by combining spaceborne MIMO-SAR and elevation DBF in order to reduce the larger range ambiguity in the spaceborne MIMO-SAR system.While transmitting orthogonal code waveforms,multiple sub-apertures don’t transmit simultaneously,but do that with certain sequence.While receiving echoes,multiple sub-apertures receive return simultaneously.Elevation receive DBF is used to separated echoes and reduce range ambiguity.Moreover,the primary system parameters,including PRF,delay between sub-aperture,radar equation and data rate,are analyzed.Simulation results confirm that DBF-MIMO-SAR is efficient to realize high resolution and wide swath.关键词：spaceborne synthetic aperture radar (SAR);multiple input multiple output (MIMO);digital beamforming (DBF);high resolution wide swath (HRWS);range ambiguity0|2|10更新时间：2025-07-02
- 摘要：In ballistic missile defense,the situation of unresolved targets is of great threaten to the tracking,identification and guidance of ground based radars,and some special efforts must be adopted to deal with it,among which the detection of the presence of unresolved targets is the precondition and basis of all the others.It is indicated by tests that,when multiple unresolved targets exist,the main lob’s phase of LFM pulse compress output changes tempestuously,other than single target case where the phase changes tardily.The difference between those two cases above can provide a new way to detect the presence of unresolved targets.In this paper,the model of sample phase error is put forward,and its statistic characteristics under the condition of single target and multiple unresolved targets are derived.Based on what above,a general likelihood ratio test is developed to detect the presence of unresolved targets.Finally,the Monte Carlo simulation result identifies the validity of the models.关键词：linear frequency modulation (LFM);phase characteristics;multiple unresolved targets;sample phase error;general likelihood ratio0|2|7更新时间：2025-07-02
- 摘要：An unsupervised classification method making use of Shannon entropy parameter is proposed for polarimetric interferometric SAR (PolInSAR) data.Shannon Entropy measures the statistical disorder of the medium illuminated by the radar,and it can be decomposed into the the sum of three different terms that respectively represent the contribution of intensity,polarimetry and interferometry.Interferometric term parameter of the Shannon entropy is combined with Wishart maximum likelihood clustering to initially segment the SAR image into several classes.Those initial classes are further divided into several subclasses through the intensity term and polarimetric term parameter of the Shannon entropy,and then each initial classes are merged to desired number of classes through agglomerative hierarchical clustering method.关键词：PolInSAR;Shannon entropy;Wishart clustering;agglomerative hierarchical clustering0|2|5更新时间：2025-07-02
- 摘要：A novel blind detection algorithm based on finite-difference for interpolation permuted image was proposed in this paper.The periodic property of difference sequence was detected by finite-difference for interpolated signal,according to the periodic property,the various interpolation factor could be identified.The algorithm has simple principle and small computational load.Simulation results show a high detection accuracy on the permuted image with various interpolation operations.The proposed algorithm indicates a better performance on the robustness against gaussian noise and lossy JPEG compression.关键词：permuted image;interpolation detection;finite-difference;periodic property;blind authentication0|2|7更新时间：2025-07-02
- 摘要：A unified model for image denoising is proposed based on the analysis of several denoising methods.It by designing a unified objective function leads the image denoising into an optimization problem.The objective function builds up with three parts:the residual error penalty function,the local weighting function and the regularization term.Under this unified model,a novel nonlinear filtering algorithm for removing salt-and-pepper noise is subsequently proposed,in which the residual error penalty function in the form of L1 norm,the weighting function utilizes the adaptive Gaussian kernel,and the regularization term is constructed by using the apriority of image’s sparse property in wavelet domain.Since the proposed model fully considers the global and local statistical property of image,and hence behaves much better in edge preservation.Experimental results demonstrate the effectiveness of the proposed method.关键词：image noising;nonlinear filtering;adaptive weighing;detail-preserving0|2|5更新时间：2025-07-02
- 摘要：In this paper,we propose a method to restore a single haze image using segmentation algorithm.Firstly,the dark channel prior is used to estimate the rough transmission.Using laplacian matting matrix,we can matting the transmission that is segmented.When the scene objects are inherently similar to the atmospheric light,the transmission map is rectified by belief propagation algorithm.Using the transmission map that is repaired and rectified and the haze image optical model,we can physically recover the scene radiance.The experimental results demonstrate the new method abilities to remove the haze layer as well as provide a reliable depth map.关键词：image restoration;segment matting;dehaze/defog;dark channel prior0|2|30更新时间：2025-07-02
- 摘要：Knowledge of X-ray spectra is essential for X-ray dose control,X-ray image quality evaluation and dual-energy X-ray imaging etc.A model-based tungsten anode X-ray tube spectra reconstruction method is presented in this paper.A physical meaningful seven-parameter X-ray tube spectra model is firstly established.Then model parameters are estimated from attenuation data so that X-ray tube spectra can be reconstructed.In the experiment,a series of aluminum plates and copper plates with different thickness are selected as attenuator for a selected tube voltage.Model parameters are estimated from experimentally measured attenuation data to reconstruct X-ray tube spectra.Experiments show that the method is easy to apply and can reconstruct both bremsstrahlung and characteristic spectra with only a few attenuation data.The difference of attenuation data between initial spectra and reconstructed spectra is lower than 0.3%.The difference between modified handbook spectra and reconstructed spectra is lower than 5%.关键词：X-ray tube spectra model;spectra reconstruction;attenuation data0|2|4更新时间：2025-07-02
- 摘要：A pattern synthesis with desired magnitude response based on the combination of genetic algorithm and convex optimization is proposed.The phase in mainlobe is used as the optimization variables for genetic algorithm,and the fitness function is constructed with the desired magnitude of mainlobe.The optimal fitness degree for the corresponding individual can be obtained through solving the fitness function with the convex optimization,which greatly improves the algorithm search performance.The phase optimization makes the synthesis result with the proposed algorithm has no relation to the array reference point and the algorithm is suit for the arbitrary array synthesized.The validity of method is confirmed by the result of the simulate data.关键词：phased arrays;array pattern synthesis;convex optimization;magnitude0|2|7更新时间：2025-07-02
- 摘要：In order to realize accurate tracking task with wireless sensor network,a signal character sequence particle filter algorithm is proposed which is generic and compatible with different physical layers.The signal character sequences are used to translate the signal from the physical layer to the abstract layer and realize the update of the particle weights.To overcome the degeneration and impoverishment problems of the classical particle filter algorithm,trace prediction,cross operation and resample method are proposed to sample particles from the posterior distribution.In addition to the basic algorithm,multidimensional filtering is also adopted to deal with the noise.Simulation results show the effectiveness of the improvement measures of the algorithm.关键词：wireless sensor network;tracking;particle filter;signal character sequence0|2|4更新时间：2025-07-02
- 摘要：A network coding based cooperative communication mechanism (NCCC) is proposed.Wireless network coding can suppress outrage probability when achieving the performance gain by cooperative diversity.A distributed algorithm of relay selection can maximize the average capacity by choosing the appropriate set of relay nodes for the operation of network coding according to the instantaneous link condition.The theoretic and simulation results show that NCCC can enhance the robustness and performance for bidirectional data transmission between multi-source and multi-destination in wireless network.关键词：network coding;wireless mesh network;fairly cooperative communication0|2|3更新时间：2025-07-02
- 摘要：Based on network coding,a retransmission-free routing (RFR) algorithm is proposed,in which an optimization model that minimizes energy cost per bit of useful data is presented and solved by genetic algorithms.The RFR reduces energy cost of nodes,alleviates radio interferences among nodes,and eliminates memory used to buffer packets for retransmitting.关键词：Wireless sensor networks;routing;power-saving;network coding0|2|9更新时间：2025-07-02
- 摘要：According to the shortcoming of traditional spray routing in dynamic opportunistic networks,an adaptive multi-copy routing protocol based on seed spray (ASSR) was proposed in this paper.ASSR calculates the number of seeds and estimates the routing cost in source node,and make spray decisions in relay nodes which have fresher knowledge of the networking conditions than the source.ASSR utilizes only a small quantity of seed nodes to spray message copies for reducing redundant copies.Simulations show that ASSR show prominent superiority in routing cost and adaptability,and is an efficient delay-bounded multi-copy routing protocol for opportunistic networks especially in dynamic conditions.关键词：opportunistic networks;delay-bounded;adaptive;spray routing0|2|6更新时间：2025-07-02
- 摘要：There are many types of data co-existing in wireless multimedia sensor networks,which have different quality of service requirements.So quality of service is an important issue of wireless multimedia sensor networks.This paper proposes an angle-based differentiated services routing algorithm.Nodes in this new algorithm select appropriate transmitting region which is classified by its deviate angel for different types of date streams,and choose the appropriate route based on local neighbor information such as neighboring node position,single-hop communication cost and residual energy.The simulation results showed that the proposed algorithm outperforms some well-known routing algorithms in terms of multimedia data stream delay,jitter,packet loss rate and power consumption.关键词：wireless multimedia sensor networks;Quality of Service;differentiated service;routing0|2|8更新时间：2025-07-02
- 摘要：In this paper,a swarm intelligence based QoS (Quality of Service) unicast routing scheme in SON (Self-Organizing Network) is proposed.Inexact routing information is described with fuzzy mathematics at the same time profits of both user and network provider are taken into account with microeconomics.Based on AntNet algorithm,a QoS unicast path is found with Pareto optimum under Nash equilibrium of both user and network provider utilities achieved or approached.The proposed scheme is implemented by simulation over NS2 (Network Simulator 2) and its performance is evaluated.It was shown that the proposed scheme had good performance on user utility,network provider utility,path comprehensive evaluation value,Pareto optimum ratio under Nash equilibrium and routing success ratio.关键词：SON (Self-Organizing Network);AntNet;QoS (Quality of Service);unicast;routing0|2|2更新时间：2025-07-02
- 摘要：This paper presents a high energy-efficient cluster-based data collecting and routing protocol (HEEDC) for wireless sensor networks,in which a node,according to its status (a weighted parameter),independently makes its decision to compete for acting as a cluster head.Furthermore,HEEDC uses the multi-hop manner for inter-cluster data transmission in order to save total energy consumption.A specialized cluster head node is responsible for collecting the data from other cluster head nodes,and then transmits the aggregated data to the base station.Experimental results show that compared with the current important clustering protocols,the HEEDC protocol provides higher performance and longer network lifetime.Therefore,the reliability and availability in HEEDC is higher than that in other protocols.关键词：Wireless sensor networks;energy-efficient;cluster;routing protocol;coverage;node density0|2|13更新时间：2025-07-02
- 摘要：Because of the natural interference or the requirement of network planning,wireless links are intermittently connected in wireless networks,which are called intermittently connected wireless networks (ICN).The routing optimization in ICNs is a new challenge because it requires to consider the links'characteristics of both time-relevant and space-relevant.This paper proposed a novel routing algorithm,Dynamic Programming Routing Algorithm (DPRA),for ICNs.DPRA is based on statistical characteristics of wireless links,and uses the dynamic programming method to choose the shortest delay path.Simulation results indicate that the proposed routing algorithm is effective.0|2|0更新时间：2025-07-02
- 摘要：To avoid the transfer congestion and solve the problem of high priority throughput decreasing when low priority data stream increase in Ad hoc,a wireless multi-hop QoS framework and adaptive cooperation channel access algorithm named QAC-EDCA(QoS guaranteed Adaptive Cooperation EDCA) are proposed.QAC-EDCA base on 802.11e and expand its priority differentiation mechanism to three layer priority mechanism.Through mapping the QoS demand into slot utilization for QoS fulfill status judgement and broadcast contention window adjusting information in two hop area through control frame,the high priority stream can rob the bandwidth of low priority stream and the transfer congestion station can get more bandwidth from neighbor stations.Simulation proves that QAC-EDCA can protect high priority quality of service better than 802.11e in wireless multi-hop transmission surroundings.关键词：adaptive cooperation;Ad hoc;802.11e;Quality of Service;slot utilization;reception avoiding;priority0|2|1更新时间：2025-07-02
- 摘要：To assure the security of the spatial information network,security control mechanics will be implemented whenever,wherever,and whoever an information terminal or an aircraft accesses the spatial network.In this paper,a bidirectional authentication and key negotiation protocol with signature based authentication model by using Diffie-Hellman key exchange technique is presented between the access points and the aircrafts when the aircrafts access into the spatial information network or roam between the different sub-networks.Analysis shows that the proposed protocol is universally composable secure under DDH assumption.关键词：spatial information network;universally composable secure;authentication and key exchange;DDH assumption0|2|9更新时间：2025-07-02
- 摘要：In the context of signal interception applications,a novel model based on missing-data model is proposed to the blind synchronization and the estimation of the spreading waveform for the long code Direct Sequence Spreading Spectrum (DS-SS) signals.In the blind synchronization step,the Frobenius norm maximization algorithm,a classic blind synchronization method used in short code DS-SS signals,is extended to our missing-data model and its asymptotic efficiency is verified; in the step of spreading waveform estimation,an alternative projection (AP) algorithm with low computational complexity used to weighted low-rank approximation (WLRA) is proposed.Based on the missing-data model,the proposed method can directly exploit the received data.Therefore,significant performance improvement is observed in simulations,especially under the scenarios with short data length,than other existing approaches,which only exploit the auto-correlation matrix of the received data and lead to obvious performance loss.关键词：signal interception;blind synchronization;spreading waveform estimation;missing-data model;weighted low rank approximation0|2|3更新时间：2025-07-02
- 摘要：Reversible computing is an emerging area of research.The reversible logic gate cascade is the important composition parts of the reversible logic synthesis.This paper proposed the reversible logic gate network cascade method-based the reversible logic gate coding and the variable system numbers,which can generate single reversible network or the batching continuous sequence numbers reversible network.Via the corresponding relationship between the variable system numbers and reversible network output vectors,we can locate quickly the corresponding sequence numbers of the reversible network output vectors and judge preciously whether the output vectors have been appeared meanwhile reducing the times of search and search space.Compared with examples of the benchmark,the number of control-bits and the number of the reversible logic gates has been improved to some degree.关键词：reversible computing;reversible logic synthesis;reversible logic;reversible network;reversible gate cascade0|2|6更新时间：2025-07-02
- 摘要：This paper proposes a propagator-based algorithm for underwater acoustic 2-D direction-of-arrival (DOA) estimation with an array of acoustic vector sensors.Firstly,the propagator method is exploited to extract a set of high accurate but ambiguous DOA estimates;then,the character of acoustic vector is exploited to extract another set of low accurate but unambiguous DOA estimates;finally,the unambiguous DOA estimates are used to disambiguate the ambiguous DOA estimates to yield high accurate and unambiguous DOA estimates.The proposed algorithm requires no eigen-decomposition or singular value decomposition into the signal and noise subspaces.Comparing with its ESPRIT counterpart,the proposed propagator algorithm has its computational complexity reduced by this ratio:the number of sources to quadruple the number of acoustic vector sensors.Simulation results show that at high and medium signal-to-noise ratio,the proposed propagator algorithm’s estimation accuracy is similar to its ESPRIT counterpart.关键词：acoustic vector sensor;direction-of-arrival estimation;extended-aperture;propagator method0|2|5更新时间：2025-07-02
- 摘要：Shape distortion may deteriorate the left/right discrimination performance of twin-line array sonar.A typical shape distortion was discussed where the twin lines of sonar deviate from the axial direction.A distortion variable was defined,and the function relation between the left/right suppression ratio and the variable was deduced.Then the characteristic bearing and the characteristic frequency,two important performance indexes,were calculated to analyze the influence created by the shape distortion.Also the performance of several traditional left/right discrimination methods were discussed under the situation of shape distortion.Simulation results showed that this typical shape distortion had great affects on the discrimination performance of twin-line array sonar,especially on the beam bearing,where the discrimination results may be contrary to the real state.The time delay method and the conventional method based on twin-line array directivity would lose their precision to some extent,and modification was necessary.关键词：shape distortion;twin-line array;left/right discrimination;left/right suppression ratio;characteristic bearing;characteristic frequency0|2|6更新时间：2025-07-02
- 摘要：Current router architectures based on single-stage switch with centralized scheduling cannot meet the Internet development requirements in terms of traffic,the number of hosts and applications.In the last couple of years,high performance switches in order to promote the scalability,throughput and QoS capabilities of Internet routers have attracted more and more attention in the area of router technology.The paper presents a survey of high performance switch design from aspects of architecture,scheduling strategy and QoS features,further analyses and compares the scheduling algorithms for each switch architecture in terms of scalability,implementation complexity,delay and throughput guarantees,load balancing and packet reordering.Finally,future directions and possible open problems are discussed.关键词：switch architecture;buffered crossbar;load-balanced switch;parallel packet switch;multi-stage switch0|2|2更新时间：2025-07-02
- 摘要：In MIMO systems,uniform channel decomposition (UCD) has been proven to be optimal in BER performance and strictly capacity lossless when perfect channel state information (CSI) is assumed to be available at both the transmitter and receiver side.However,in practice,CSI is always contaminated by channel estimation error.In this paper,we proposed a novel robust UCD scheme based on limited feedback,which consider channel estimation error as an integral part of the system design.Using Shannon rate-distortion theory and generalized Lloyd vector quantization algorithm (GLA),we obtain approximate channel estimation error which enhances the practicability of our proposed algorithm.It is shown in the simulation results that our proposed robust UCD scheme is capable of improving the BER ceiling and capacity performance compared with the conventional UCD scheme.关键词：MIMO;robust design;uniform channel decomposition (UCD);limited feedback0|2|1更新时间：2025-07-02
- 摘要：An 8mm wave Fabry-Perot resonator was designed and fabricated by the technique of three-dimensional electromagnetic simulation.A measurement system for the characterization of high temperature superconductor Josephson junction was set up based on the Fabry-Perot resonator.The millimeter wave irradiation characteristic of Tl2Ba2CaCu2O8(Tl-2212)high temperature superconducting thin film bicrystal Josephson junction was measured using the system and high quality Shapiro steps were observed.Taking advantage of the Fabry-perot resonator technique,the efficiency of the coupling between applied electromagnetic wave and Josephson junction was enhanced markedly by compared with the measured results using U-type waveguide measurement system,which is greatly significant for the investigation of radiation and detection of millimeter/submillimeter wave and terahertz wave.关键词：high temperature superconducting thin film;fabry-perot resonator;Josephson junction;shapiro step0|2|1更新时间：2025-07-02
- 摘要：Based on the eminent characteristics of opportunistic relaying cooperative communication system,this paper improves the conventional multi-relay ARQ (Automatic Repeat Request)cooperative diversity scheme,and optimizes the utility of wireless spectrum and energy by designing physical layer and data link layer jointly.The end-to-end performance analytical model using absorbing Markov chain is firstly proposed.With the application of this proposed analytical model,we analyze our improved opportunistic cooperative retransmission protocol’s performance parameters in terms of probability of end-to-end delivery success,probability of end-to-end delivery failure,delay,and throughput.Simulation results are finally provided to verify the correctness of our proposed analytical model,and the effects of the maximal retransmission times,channel fading parameters,and total transmission power on performance are discussed in detail.Our numerical results show that our improved opportunistic cooperative retransmission protocol has several desirable characteristics in energy saving and channel fading overcoming compared to other schemes,such as direct retransmission protocol and conventional multi-relay cooperative retransmission protocol.关键词：cooperative diversity;opportunistic relaying;absorbing Markov chain0|2|1更新时间：2025-07-02
- 摘要：Scheduling of scientific workflow is becoming more challenging for autonomous grid and egoism of competitive market.We proposed market-driven scientific workflow scheduling framework (MSWSF) in utility grid to consider the benefits of both scientific users and service providers.Equilibrium pricing scheme derives service price under multiple resource constraints to achieve optimal allocation of resources and maximal profits of service providers.Cost optimization mapping strategy introduces a cost gradient metric as a criterion for service selection in order to improve optimization capability and speed.Performance simulation proves MSWSF not only can achieve high average profits of resource nodes and resource utilization rate,but also can optimize usage cost of different types of scientific workflows while satisfying QoS requirements.关键词：grid computing;task scheduling;scientific workflow;service pricing0|2|2更新时间：2025-07-02
- 摘要：Based on the adaptive least mean squares algorithm,the LMS spectrum analyzer can be applied to recursively compute the discrete Fourier transform of a sliding window of data.In this paper,a LMS-based method for calculating multisample-based sliding-DFT is proposed.The method establishes the relationship between LMS algorithm and sliding-DFT when new multisamples come into the sliding window for DFT.The inferential formula is deduced,meanwhile,the computer simulation is performed for validation.The method is effective and available for arbitrary transform length and sliding step size.关键词：DFT;LMS algorithm;sliding window0|2|0更新时间：2025-07-02
- 摘要：The inherent delay-Doppler coupling of stepped-frequency radar has a severe impact on the united resolution of range and velocity.In order to achieve high resolution ability of range and velocity simultaneously,jumped-frequency radar signal which has thumbtack-shaped ambiguity function is used to resolve the delay-Doppler coupling.In this paper the uniform ambiguity function of jumped-frequency radar signal is deduced for the first time,and then the ambiguity and resolution characteristics of coded-frequency signal are analyzed.Then a novel STRETCH processing method is put forward for high velocity targets on the occasion of wideband Costas-coded stepped-frequency signal,which can resolve high-sidelobe problem effectively.Simulations with MATLAB indicate that the Costas-coded stepped-frequency signal performs well in the velocity measurement and high range resolution imaging.关键词：radar;wideband;velocity measurement;ambiguity function;Costas-coded0|2|9更新时间：2025-07-02
- 摘要：The image inpainting is the hot research points and have widely application.The traditional methods have good results for small area repairing,which can restore the edge structure,but can not handle the texture details and the image with big hole.A new inpainting method based on fractal theory is presented,which uses the total information of image effectively.The relation of fractal dimension and the size range block is discussed,a repair method by multi-scale fractal coding and reconstruction is proposed.In order to strengthen detail information,local fractal iterative is used.Using fractal interpolation,the image is magnified to get good recover quality.Experiments show that the proposed method has good results especially suitable for texture image and large missing image.关键词：image inpainting;image reconstruction;fractal;fractal dimension;interpolation0|2|10更新时间：2025-07-02
- 摘要：According to the heterogeneous characteristics of wireless mesh networks (WMNs) and the QoS requirements of multimedia business,we designed a QoS adaptive architecture for WMNs,which is cross-domain,cross-layer and cross-node.Furthermore,this architecture was mathematically described by a bi-level programming model.Based on this mathematical model,we proposed an ant colony optimization based routing algorithm.Simulation results show that the bi-level programming model can fully optimize various QoS parameters of paths;the proposed routing algorithm,which has both advantages of low complexity and fast convergence speed,can converge to the optimal solution of bi-level programming model.关键词：wireless mesh networks;multimedia business;routing algorithm0|2|1更新时间：2025-07-02
- 摘要：In order to improve energy efficiency and prolong lifetime of wireless sensor networks(WSNs),a new distributed algorithm for calculating minimum connected dominating set based on node’s discrete Markov chain model is proposed.A Markov Model for dominating node and dominated nodes,which is used to predict the nodes’ energy consumption,is developed.The dominating nodes act as clustering nodes in the network.The algorithm runs multi-rounds.In the beginning of every round,dominating nodes are elected based on nodes’ degree and energy,and the time this round will last is computed,.After this round,the network will re-elect dominating nodes and run the next round.Simulation results show that,compared to the original algorithm,the new algorithm can prolong the lifetime of the network evidently while balancing energy consumption and increasing energy efficiency.0|2|4更新时间：2025-07-02
- 摘要：In the environment of multiple networks coexisting and sharing spectrum,the issue of group-blind multiuser detection (GBMUD) and GBMUD coalition formation among wireless nodes is addressed under the framework of coalitional game.Firstly,a stochastic multiuser detection model with transferable payoffs (stochastic TU-Model) from system viewpoint is presented;secondly,a model with non-transferable payoffs (NTU-Model) focusing on each MS's preference is introduced;finally,a coalition formation algorithm that maximizes the average users’ throughput is derived on the base of the above research results,and is further verified by simulation.关键词：coalitional game;group blind multiuser detection (GBMUD);coalition formation algorithm0|2|2更新时间：2025-07-02
- 摘要：Space-time trellis codes (STTC) in multiband orthogonal frequency division multiplexing (MB-OFDM) systems with Rayleigh fading channels is proposed and diversity performance with spatial correlation between the transmit antennas is analyzed.STTC converts the single output code symbol into several code symbols,which are to be transmitted simultaneously from multiple transmitter antennas.Viterbi optimal soft decision decoding algorithm is used at the receiver.We investigate both quasi-static and interleaved channels and demonstrate how the spatial fading correlation affects the performance over these two different MB-OFDM wireless channel models.Diversity order is preserved when the spatial correlation is small.While spatial correlation becomes larger,diversity order could maintain in interleaved channels but decrease in quasi-static channels.In general,the performance of space time codes is observed to be robust to spatial correlation.关键词：ultra wideband (UWB);multiband orthogonal frequency division multiplexing (MB-OFDM);space-time trellis codes (STTC);pairwise error probability (PEP);diversity order0|2|0更新时间：2025-07-02
- 摘要：To introduce network coding into all-optical multicast networks,a polynomial time algorithm of establishing network coding-based two-disjoint path multicast tree is presented in the paper.There are two major steps in the algorithm:firstly,determining a directed path between the source node and each destination node in the given multicast network according to the degree balance principle of the intermediated nodes.The traditional directed multicast tree is obtained by determining the directed paths between the source node and all destination nodes,and the out-degree of each intermediated nodes are reduced as small as possible.Secondly,confirming the second path between the source node and the destination nodes from each destination node to the source node according to the conflict-backtracking principle and keep the two paths are disjoint paths in the traditional directed multicast tree.The multicast tree which is established by the algorithm contains minimum number of coding nodes,and can well support the all-optical network coding in photonic domain.关键词：network coding;all-optical multicast;disjoint path;multicast tree0|2|4更新时间：2025-07-02
- 摘要：Many typical security models have been proposed,such as the BLP model and the nondeducibility model,however,these models have some disadvantages and limitations in theoretical analysis or implementation respectively.For instance,BLP model did not take the covert channel into account,and the nondeducibility model cannot be applied to the nondeterministic systems.Considering these shortages brought about by the existing works,this paper take the properties of the covert channel as a main consideration,and propose a novel finite-information-leakage-tolerance communication channel model based on the BLP model.The proposed model finds a tradeoff between the availability and security of the practical system by adjusting the upper bound of the channel capacity of the information leakage.关键词：security model;BLP model;covert channel;communication channel model0|2|5更新时间：2025-07-02
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