In view of the problems of inconsistent data semantics,inconsistent data formats,and difficult data quality assurance between the railway engineering design phase and the construction and operation phase,as well as th...In view of the problems of inconsistent data semantics,inconsistent data formats,and difficult data quality assurance between the railway engineering design phase and the construction and operation phase,as well as the difficulty in fully realizing the value of design results,this paper proposes a design and implementation scheme for a railway engineering collaborative design platform.The railway engineering collaborative design platform mainly includes functional modules such as metadata management,design collaboration,design delivery management,model component library,model rendering services,and Building Information Modeling(BIM)application services.Based on this,research is conducted on multi-disciplinary parameterized collaborative design technology for railway engineering,infrastructure data management and delivery technology,and design multi-source data fusion and application technology.The railway engineering collaborative design platform is compared with other railway design software to further validate its advantages and advanced features.The platform has been widely applied in multiple railway construction projects,greatly improving the design and project management efficiency.展开更多
In this article,the secure computation efficiency(SCE)problem is studied in a massive multipleinput multiple-output(mMIMO)-assisted mobile edge computing(MEC)network.We first derive the secure transmission rate based ...In this article,the secure computation efficiency(SCE)problem is studied in a massive multipleinput multiple-output(mMIMO)-assisted mobile edge computing(MEC)network.We first derive the secure transmission rate based on the mMIMO under imperfect channel state information.Based on this,the SCE maximization problem is formulated by jointly optimizing the local computation frequency,the offloading time,the downloading time,the users and the base station transmit power.Due to its difficulty to directly solve the formulated problem,we first transform the fractional objective function into the subtractive form one via the dinkelbach method.Next,the original problem is transformed into a convex one by applying the successive convex approximation technique,and an iteration algorithm is proposed to obtain the solutions.Finally,the stimulations are conducted to show that the performance of the proposed schemes is superior to that of the other schemes.展开更多
The centralized radio access cellular network infrastructure based on centralized Super Base Station(CSBS) is a promising solution to reduce the high construction cost and energy consumption of conventional cellular n...The centralized radio access cellular network infrastructure based on centralized Super Base Station(CSBS) is a promising solution to reduce the high construction cost and energy consumption of conventional cellular networks. With CSBS, the computing resource for communication protocol processing could be managed flexibly according the protocol load to improve the resource efficiency. Since the protocol load changes frequently and may exceed the capacity of processors, load balancing is needed. However, existing load balancing mechanisms used in data centers cannot satisfy the real-time requirement of the communication protocol processing. Therefore, a new computing resource adjustment scheme is proposed for communication protocol processing in the CSBS architecture. First of all, the main principles of protocol processing resource adjustment is concluded, followed by the analysis on the processing resource outage probability that the computing resource becomes inadequate for protocol processing as load changes. Following the adjustment principles, the proposed scheme is designed to reduce the processing resource outage probability based onthe optimized connected graph which is constructed by the approximate Kruskal algorithm. Simulation re-sults show that compared with the conventional load balancing mechanisms, the proposed scheme can reduce the occurrence number of inadequate processing resource and the additional resource consumption of adjustment greatly.展开更多
AVS2 is a new generation video coding standard developed by the AVS working group. Compared with the first generation AVS video coding standard, known as AVS1, AVS2 significantly improves coding performance by using m...AVS2 is a new generation video coding standard developed by the AVS working group. Compared with the first generation AVS video coding standard, known as AVS1, AVS2 significantly improves coding performance by using many new coding technologies, e.g., adaptive block partition and two level transform coding. Moreover, for scene video, e.g. surveillance video and conference vid?eo, AVS2 provided a background picture modeling scheme to achieve more accurate prediction, which can also make object detec?tion and tracking in surveillance video coding more flexible. Experimental results show that AVS2 is competitive with High Effi?ciency Video Coding (HEVC) in terms of performance. Especially for scene video, AVS2 can achieve 39% bit rate saving over HEVC.展开更多
DNS is one of the most important basic infrastructures of the Internet, attacks on which will prevent the Internet from working properly. Therefore, its security is receiving great concern. This paper analyzes the pri...DNS is one of the most important basic infrastructures of the Internet, attacks on which will prevent the Internet from working properly. Therefore, its security is receiving great concern. This paper analyzes the principles of both traditional and novel （Kaminsky） DNS cache poisoning, presents attack samples and describes the whole attack process in detail. After verifying the potential harm of DNS cache poisoning, the paper gives out several defense strategies.展开更多
With the increasingly fierce competition among communication operators,it is more and more important to make an accurate prediction of potential off grid users.To solve the above problem,it is inevitable to consider t...With the increasingly fierce competition among communication operators,it is more and more important to make an accurate prediction of potential off grid users.To solve the above problem,it is inevitable to consider the effectiveness of learning algo rithms,the efficiency of data processing,and other factors.Therefore,in this paper,we,from the practical application point of view,propose a potential customer off grid predic tion system based on Spark,including data pre processing,feature selection,model build ing,and effective display.Furthermore,in the research of off grid system,we use the Spark parallel framework to improve the gcForest algorithm which is a novel decision tree ensemble approach.The new parallel gcForest algorithm can be used to solve practical problems,such as the off grid prediction problem.Experiments on two real world datasets demonstrate that the proposed prediction system can handle large scale data for the off grid user prediction problem and the proposed parallel gcForest can achieve satisfying per formance.展开更多
Railway real estate is the fundamental element of railway transportation production and operation.Effective management and rational utilization of railway real estate is essential for railway asset operation.Based on ...Railway real estate is the fundamental element of railway transportation production and operation.Effective management and rational utilization of railway real estate is essential for railway asset operation.Based on the investigation of the requirements of railway real estate management and operation,combined with Beidou positioning,GIS(Geographic Information System),multi-source data fusion and other cutting-edge technologies,this paper puts forward the multi-dimensional dynamic statistical method of real estate information,the identification method of railway land occupation and the comprehensive evaluation method of real estate development and utilization potential,and build the railway real estate supervision and operation platform,design the function of the platform,so as to provide intelligent solutions for the railway real estate operation.展开更多
Novel centralized base station architectures integrating computation and communication functionalities have become important for the development of future mobile communication networks.Therefore,the development of dyn...Novel centralized base station architectures integrating computation and communication functionalities have become important for the development of future mobile communication networks.Therefore,the development of dynamic high-speed interconnections between baseband units(BBUs)and remote radio heads(RRHs)is vital in centralized base station design.Herein,dynamic high-speed switches(HSSs)connecting BBUs and RRHs were designed for a centralized base station architecture.We analyzed the characteristics of actual traffic and introduced a switch traffic model suitable for the super base station architecture.Then,we proposed a data-priority-aware(DPA)scheduling algorithm based on the traffic model.Lastly,we developed the dynamic HSS model based on the OPNET platform and the prototype based on FPGA.Our results show that the DPA achieves close to 100%throughput with lower latency and provides better run-time complexity than iOCF and HE-iSLIP,thereby demonstrating that the proposed switch system can be adopted in centralized base station architectures.展开更多
The upcoming 6G wireless networks have to provide reliable communications in high-mobility scenarios at high carrier frequencies.However,high-mobility or high carrier frequencies will bring severe inter-carrier interf...The upcoming 6G wireless networks have to provide reliable communications in high-mobility scenarios at high carrier frequencies.However,high-mobility or high carrier frequencies will bring severe inter-carrier interference(ICI)to conventional orthogonal fre⁃quency-division multiplexing(OFDM)modulation.Orthogonal time frequency space(OTFS)modulation is a recently developing multi-carrier transmission scheme for wireless commu⁃nications in high-mobility environments.This paper evaluates the performance of coded OT⁃FS systems.In particular,we consider 5G low density parity check(LDPC)codes for OTFS systems based on 5G OFDM frame structures over high mobility channels.We show the per⁃formance of the OTFS systems with 5G LDPC codes when sum-product detection algorithm and iterative detection and decoding are employed.We also illustrate the effect of channel estimation error on the performance of the LDPC coded OTFS systems.展开更多
In the Internet of things, it is of critical importance to fully utilize the potential capacity of the network with efficient medium access control （MAC） mechanisms. In this paper, we study the convergence property ...In the Internet of things, it is of critical importance to fully utilize the potential capacity of the network with efficient medium access control （MAC） mechanisms. In this paper, we study the convergence property of the fixed point formulation of distributed coordination function （DCF）, which is widely used for medium access control in wireless networks. We first Kind that the fixed point could be repelling, which means that it is impossible for an MAC system to converge at its fixed point. Next, we show the existence of periodic points to prove that the fixed point function will oscillate between two periodic points when the fixed point is repelling. We also find that the average of the two periodic points is a close approximation of the fixed point. Based on the findings, we propose an algorithm to compute the fixed point efficiently. Simulation results verify the accuracy and efficiency of our algorithm compared with the previous fixed point computing method.展开更多
This paper focuses on how to improve aspect-level opinion mining for online customer reviews. We first propose a novel generative topic model, the Joint Aspect/Sentiment (JAS) model, to jointly extract aspects and asp...This paper focuses on how to improve aspect-level opinion mining for online customer reviews. We first propose a novel generative topic model, the Joint Aspect/Sentiment (JAS) model, to jointly extract aspects and aspect-dependent sentiment lexicons from online customer reviews. An aspect-dependent sentiment lexicon refers to the aspect-specific opinion words along with their aspect-aware sentiment polarities with respect to a specific aspect. We then apply the extracted aspectdependent sentiment lexicons to a series of aspect-level opinion mining tasks, including implicit aspect identification, aspect-based extractive opinion summarization, and aspect-level sentiment classification. Experimental results demonstrate the effectiveness of the JAS model in learning aspectdependent sentiment lexicons and the practical values of the extracted lexicons when applied to these practical tasks.展开更多
The overall hardware construction of autopilot within micro aerial vehicle is presented. The boot process of VxWorks real time operating system as well as the conception and function of board support package （BSP） i...The overall hardware construction of autopilot within micro aerial vehicle is presented. The boot process of VxWorks real time operating system as well as the conception and function of board support package （BSP） is described. And the transplantation process of the VxWroks operat ing system into the hardware platform mentioned above is highlighted. It is shown from the final re sults that VxWorks has high stability and real time performance, ensuring accurate flight control and a smooth flight of the micro aerial vehicle.展开更多
Community detection methods have been used in computer, sociology, physics, biology, and brain information science areas. Many methods are based on the optimization of modularity. The algorithm proposed by Blondel et ...Community detection methods have been used in computer, sociology, physics, biology, and brain information science areas. Many methods are based on the optimization of modularity. The algorithm proposed by Blondel et al. （Blondel V D, Guillaume J L, Lambiotte R and Lefebvre E 2008 J. Star. Mech. 10 10008） is one of the most widely used methods because of its good performance, especially in the big data era. In this paper we make some improvements to this algorithm in correctness and performance. By tests we see that different node orders bring different performances and different community structures. We find some node swings in different communities that influence the performance. So we design some strategies on the sweeping order of node to reduce the computing cost made by repetition swing. We introduce a new concept of overlapping degree （OV） that shows the strength of connection between nodes. Three improvement strategies are proposed that are based on constant OV, adaptive OV, and adaptive weighted OV, respectively. Experiments on synthetic datasets and real datasets are made, showing that our improved strategies can improve the performance and correctness.展开更多
In the past decades, many cleanslate future network architectures have gained limited deployment in current Internet, due to the stability and rigidity of TCP/IP, the narrow waist of the Internet. We first propose thr...In the past decades, many cleanslate future network architectures have gained limited deployment in current Internet, due to the stability and rigidity of TCP/IP, the narrow waist of the Internet. We first propose three principles that the future Internet architecture should obey to be well-defined network architecture, i.e. supporting service innovation and enabling evolvability. By abstracting different modes from TCP/IP network and SDN technology, we argue that the centric-distributed-centric(CDC) mode has great potential for the well-defined future network architecture in which diverse network architectures could be incrementally deployed and coexist with each other. Prototype system regulated by CDC mode was developed. Experimental results reveal that CDC can support diverse architectures to coexist in the current Internet and thus enables the Internet to evolve.展开更多
In centralized cellular network architecture,the concept of virtualized Base Station(VBS) becomes attracting since it enables all base stations(BSs) to share computing resources in a dynamic manner. This can significa...In centralized cellular network architecture,the concept of virtualized Base Station(VBS) becomes attracting since it enables all base stations(BSs) to share computing resources in a dynamic manner. This can significantly improve the utilization efficiency of computing resources. In this paper,we study the computing resource allocation strategy for one VBS by considering the non-negligible effect of delay introduced by switches. Specifically,we formulate the VBS's sum computing rate maximization as a set optimization problem. To address this problem,we firstly propose a computing resource schedule algorithm,namely,weight before one-step-greedy(WBOSG),which has linear computation complexity and considerable performance. Then,OSG retreat(OSG-R) algorithm is developed to further improve the system performance at the expense of computational complexity. Simulation results under practical setting are provided to validate the proposed two algorithms.展开更多
A new centrality measure for complex networks, called resource flow centrality, is pro- posed in this paper. This centrality measure is based on the concept of the resource flow in net- works. It not only can be appli...A new centrality measure for complex networks, called resource flow centrality, is pro- posed in this paper. This centrality measure is based on the concept of the resource flow in net- works. It not only can be applied to the connected networks, but also the disconnected networks. Moreover, it overcomes some disadvantages of several common centrality measures. The perform- ance of the proposed measure is compared with some standard centrality measures using a classic dataset and the results indicate the proposed measure performs more reasonably. The statistical dis- tribution of the proposed centrality is investigated by experiments on large scale computer generated graphs and two networks from the real world.展开更多
Cloud computing provides a new paradigm for hardware and software infrastructure design as well as planning and usage of information systems. It offers flexible, efficient, inexpensive, and quality services. This pape...Cloud computing provides a new paradigm for hardware and software infrastructure design as well as planning and usage of information systems. It offers flexible, efficient, inexpensive, and quality services. This paper proposes an on-demand service system using the cloud computing architecture and analyzes important issues such as organization, management, and monitoring of distributed service resources; context-aware on-demand service modeling, on-demand automated service composition in large-scale networks, and service system analysis based on complex system theory. Continuous Operating Reference Station （CORS） of a geo-spatial information system is taken as an example, and its architecture is analyzed from the perspective of cloud computing. Some fundamental questions are raised about its service.展开更多
In recent years,as China has finished the updating of the fourth generation of network,for guaranteeing the information security of the state,communication chip with complete independent intellectual property right mu...In recent years,as China has finished the updating of the fourth generation of network,for guaranteeing the information security of the state,communication chip with complete independent intellectual property right must be possessed to support the advancement of such project.TD-LTE Baseband Chip is a super-large-scale integrated circuit designed basing on SOC,which needs to carry out coding,etc to the transmitted baseband signal,or carry out decoding,etc to the received baseband signal.LPDDR2 SDRAM is used in the chip design process due to its low power dissipation,high capacity and high reliability.As PHY in the controller architecture of LPDDR2 SDRAM adopts hard core design,it cannot be achieved in Virtex-7 2000T prototype verification platform.This design mainly builds on such prototype verification platform to propose the verification scheme of LPDDR2 SDRAM controller in TD_LTE baseband chip,so as to guarantee that prototype verification in FPGA can be carried out by TD_LTE baseband system,and meanwhile high capacity storage space can be provided to the system.展开更多
Low-Earth-Orbit satellite constellation networks(LEO-SCN)can provide low-cost,largescale,flexible coverage wireless communication services.High dynamics and large topological sizes characterize LEO-SCN.Protocol develo...Low-Earth-Orbit satellite constellation networks(LEO-SCN)can provide low-cost,largescale,flexible coverage wireless communication services.High dynamics and large topological sizes characterize LEO-SCN.Protocol development and application testing of LEO-SCN are challenging to carry out in a natural environment.Simulation platforms are a more effective means of technology demonstration.Currently available simulators have a single function and limited simulation scale.There needs to be a simulator for full-featured simulation.In this paper,we apply the parallel discrete-event simulation technique to the simulation of LEO-SCN to support large-scale complex system simulation at the packet level.To solve the problem that single-process programs cannot cope with complex simulations containing numerous entities,we propose a parallel mechanism and algorithms LP-NM and LP-YAWNS for synchronization.In the experiment,we use ns-3 to verify the acceleration ratio and efficiency of the above algorithms.The results show that our proposed mechanism can provide parallel simulation engine support for the LEO-SCN.展开更多
As an important branch of information security algorithms,the efficient and flexible implementation of stream ciphers is vital.Existing implementation methods,such as FPGA,GPP and ASIC,provide a good support,but they ...As an important branch of information security algorithms,the efficient and flexible implementation of stream ciphers is vital.Existing implementation methods,such as FPGA,GPP and ASIC,provide a good support,but they could not achieve a better tradeoff between high speed processing and high flexibility.ASIC has fast processing speed,but its flexibility is poor,GPP has high flexibility,but the processing speed is slow,FPGA has high flexibility and processing speed,but the resource utilization is very low.This paper studies a stream cryptographic processor which can efficiently and flexibly implement a variety of stream cipher algorithms.By analyzing the structure model,processing characteristics and storage characteristics of stream ciphers,a reconfigurable stream cryptographic processor with special instructions based on VLIW is presented,which has separate/cluster storage structure and is oriented to stream cipher operations.The proposed instruction structure can effectively support stream cipher processing with multiple data bit widths,parallelism among stream cipher processing with different data bit widths,and parallelism among branch control and stream cipher processing with high instruction level parallelism;the designed separate/clustered special bit registers and general register heaps,key register heaps can satisfy cryptographic requirements.So the proposed processor not only flexibly accomplishes the combination of multiple basic stream cipher operations to finish stream cipher algorithms.It has been implemented with 0.18μm CMOS technology,the test results show that the frequency can reach 200 MHz,and power consumption is 310 mw.Ten kinds of stream ciphers were realized in the processor.The key stream generation throughput of Grain-80,W7,MICKEY,ACHTERBAHN and Shrink algorithm is 100 Mbps,66.67 Mbps,66.67 Mbps,50 Mbps and 800 Mbps,respectively.The test result shows that the processor presented can achieve good tradeoff between high performance and flexibility of stream ciphers.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB2600405).
文摘In view of the problems of inconsistent data semantics,inconsistent data formats,and difficult data quality assurance between the railway engineering design phase and the construction and operation phase,as well as the difficulty in fully realizing the value of design results,this paper proposes a design and implementation scheme for a railway engineering collaborative design platform.The railway engineering collaborative design platform mainly includes functional modules such as metadata management,design collaboration,design delivery management,model component library,model rendering services,and Building Information Modeling(BIM)application services.Based on this,research is conducted on multi-disciplinary parameterized collaborative design technology for railway engineering,infrastructure data management and delivery technology,and design multi-source data fusion and application technology.The railway engineering collaborative design platform is compared with other railway design software to further validate its advantages and advanced features.The platform has been widely applied in multiple railway construction projects,greatly improving the design and project management efficiency.
基金The Natural Science Foundation of Henan Province(No.232300421097)the Program for Science&Technology Innovation Talents in Universities of Henan Province(No.23HASTIT019,24HASTIT038)+2 种基金the China Postdoctoral Science Foundation(No.2023T160596,2023M733251)the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University(No.2023D11)the Song Shan Laboratory Foundation(No.YYJC022022003)。
文摘In this article,the secure computation efficiency(SCE)problem is studied in a massive multipleinput multiple-output(mMIMO)-assisted mobile edge computing(MEC)network.We first derive the secure transmission rate based on the mMIMO under imperfect channel state information.Based on this,the SCE maximization problem is formulated by jointly optimizing the local computation frequency,the offloading time,the downloading time,the users and the base station transmit power.Due to its difficulty to directly solve the formulated problem,we first transform the fractional objective function into the subtractive form one via the dinkelbach method.Next,the original problem is transformed into a convex one by applying the successive convex approximation technique,and an iteration algorithm is proposed to obtain the solutions.Finally,the stimulations are conducted to show that the performance of the proposed schemes is superior to that of the other schemes.
基金supported in part by the National Science Foundationof China under Grant number 61431001the Beijing Talents Fund under Grant number 2015000021223ZK31
文摘The centralized radio access cellular network infrastructure based on centralized Super Base Station(CSBS) is a promising solution to reduce the high construction cost and energy consumption of conventional cellular networks. With CSBS, the computing resource for communication protocol processing could be managed flexibly according the protocol load to improve the resource efficiency. Since the protocol load changes frequently and may exceed the capacity of processors, load balancing is needed. However, existing load balancing mechanisms used in data centers cannot satisfy the real-time requirement of the communication protocol processing. Therefore, a new computing resource adjustment scheme is proposed for communication protocol processing in the CSBS architecture. First of all, the main principles of protocol processing resource adjustment is concluded, followed by the analysis on the processing resource outage probability that the computing resource becomes inadequate for protocol processing as load changes. Following the adjustment principles, the proposed scheme is designed to reduce the processing resource outage probability based onthe optimized connected graph which is constructed by the approximate Kruskal algorithm. Simulation re-sults show that compared with the conventional load balancing mechanisms, the proposed scheme can reduce the occurrence number of inadequate processing resource and the additional resource consumption of adjustment greatly.
文摘AVS2 is a new generation video coding standard developed by the AVS working group. Compared with the first generation AVS video coding standard, known as AVS1, AVS2 significantly improves coding performance by using many new coding technologies, e.g., adaptive block partition and two level transform coding. Moreover, for scene video, e.g. surveillance video and conference vid?eo, AVS2 provided a background picture modeling scheme to achieve more accurate prediction, which can also make object detec?tion and tracking in surveillance video coding more flexible. Experimental results show that AVS2 is competitive with High Effi?ciency Video Coding (HEVC) in terms of performance. Especially for scene video, AVS2 can achieve 39% bit rate saving over HEVC.
文摘DNS is one of the most important basic infrastructures of the Internet, attacks on which will prevent the Internet from working properly. Therefore, its security is receiving great concern. This paper analyzes the principles of both traditional and novel （Kaminsky） DNS cache poisoning, presents attack samples and describes the whole attack process in detail. After verifying the potential harm of DNS cache poisoning, the paper gives out several defense strategies.
基金supported by ZTE Industry-Academia-Research Cooperationthe National Key Research and Development Program of China under Grant No.2017YFB1002104+1 种基金the National Natural Science Foundation of China under Grant Nos.U1836206,U1811461,and 61773361the Project of Youth Innovation Promotion Association CAS under Grant No.2017146
文摘With the increasingly fierce competition among communication operators,it is more and more important to make an accurate prediction of potential off grid users.To solve the above problem,it is inevitable to consider the effectiveness of learning algo rithms,the efficiency of data processing,and other factors.Therefore,in this paper,we,from the practical application point of view,propose a potential customer off grid predic tion system based on Spark,including data pre processing,feature selection,model build ing,and effective display.Furthermore,in the research of off grid system,we use the Spark parallel framework to improve the gcForest algorithm which is a novel decision tree ensemble approach.The new parallel gcForest algorithm can be used to solve practical problems,such as the off grid prediction problem.Experiments on two real world datasets demonstrate that the proposed prediction system can handle large scale data for the off grid user prediction problem and the proposed parallel gcForest can achieve satisfying per formance.
基金supported by the Scientific and Technological Research and Development Plan of China Railway Beijing Group Co.,Ltd.(2022CT01).
文摘Railway real estate is the fundamental element of railway transportation production and operation.Effective management and rational utilization of railway real estate is essential for railway asset operation.Based on the investigation of the requirements of railway real estate management and operation,combined with Beidou positioning,GIS(Geographic Information System),multi-source data fusion and other cutting-edge technologies,this paper puts forward the multi-dimensional dynamic statistical method of real estate information,the identification method of railway land occupation and the comprehensive evaluation method of real estate development and utilization potential,and build the railway real estate supervision and operation platform,design the function of the platform,so as to provide intelligent solutions for the railway real estate operation.
基金the key project of the National Science and Technology Major Project(Grant No.2018ZX03001017)the project of the CAS engineering laboratory for intelligent agricultural machinery equipment(Grant No.GC201907-02).
文摘Novel centralized base station architectures integrating computation and communication functionalities have become important for the development of future mobile communication networks.Therefore,the development of dynamic high-speed interconnections between baseband units(BBUs)and remote radio heads(RRHs)is vital in centralized base station design.Herein,dynamic high-speed switches(HSSs)connecting BBUs and RRHs were designed for a centralized base station architecture.We analyzed the characteristics of actual traffic and introduced a switch traffic model suitable for the super base station architecture.Then,we proposed a data-priority-aware(DPA)scheduling algorithm based on the traffic model.Lastly,we developed the dynamic HSS model based on the OPNET platform and the prototype based on FPGA.Our results show that the DPA achieves close to 100%throughput with lower latency and provides better run-time complexity than iOCF and HE-iSLIP,thereby demonstrating that the proposed switch system can be adopted in centralized base station architectures.
基金supported by National Key R&D Program of Chi⁃na(No.2020YFB1807802)the National Science Fund for Distinguished Young Scholars(No.61901453)Jiangsu Provincial Key Research and Development Program(No.BE2021013-2)。
文摘The upcoming 6G wireless networks have to provide reliable communications in high-mobility scenarios at high carrier frequencies.However,high-mobility or high carrier frequencies will bring severe inter-carrier interference(ICI)to conventional orthogonal fre⁃quency-division multiplexing(OFDM)modulation.Orthogonal time frequency space(OTFS)modulation is a recently developing multi-carrier transmission scheme for wireless commu⁃nications in high-mobility environments.This paper evaluates the performance of coded OT⁃FS systems.In particular,we consider 5G low density parity check(LDPC)codes for OTFS systems based on 5G OFDM frame structures over high mobility channels.We show the per⁃formance of the OTFS systems with 5G LDPC codes when sum-product detection algorithm and iterative detection and decoding are employed.We also illustrate the effect of channel estimation error on the performance of the LDPC coded OTFS systems.
基金supported by the National Basic Research Program of China(No.2011CB302702)the NationalNatural Science Foundation of China(Nos.60803140,60970133,61070187)
文摘In the Internet of things, it is of critical importance to fully utilize the potential capacity of the network with efficient medium access control （MAC） mechanisms. In this paper, we study the convergence property of the fixed point formulation of distributed coordination function （DCF）, which is widely used for medium access control in wireless networks. We first Kind that the fixed point could be repelling, which means that it is impossible for an MAC system to converge at its fixed point. Next, we show the existence of periodic points to prove that the fixed point function will oscillate between two periodic points when the fixed point is repelling. We also find that the average of the two periodic points is a close approximation of the fixed point. Based on the findings, we propose an algorithm to compute the fixed point efficiently. Simulation results verify the accuracy and efficiency of our algorithm compared with the previous fixed point computing method.
基金supported by National Natural Science Foundation of China under Grants No.61232010, No.60903139, No.60933005, No.61202215, No.61100083National 242 Project under Grant No.2011F65China Information Technology Security Evaluation Center Program under Grant No.Z1277
文摘This paper focuses on how to improve aspect-level opinion mining for online customer reviews. We first propose a novel generative topic model, the Joint Aspect/Sentiment (JAS) model, to jointly extract aspects and aspect-dependent sentiment lexicons from online customer reviews. An aspect-dependent sentiment lexicon refers to the aspect-specific opinion words along with their aspect-aware sentiment polarities with respect to a specific aspect. We then apply the extracted aspectdependent sentiment lexicons to a series of aspect-level opinion mining tasks, including implicit aspect identification, aspect-based extractive opinion summarization, and aspect-level sentiment classification. Experimental results demonstrate the effectiveness of the JAS model in learning aspectdependent sentiment lexicons and the practical values of the extracted lexicons when applied to these practical tasks.
基金Supported by the Ministerial Level Foundation(A222006450)
文摘The overall hardware construction of autopilot within micro aerial vehicle is presented. The boot process of VxWorks real time operating system as well as the conception and function of board support package （BSP） is described. And the transplantation process of the VxWroks operat ing system into the hardware platform mentioned above is highlighted. It is shown from the final re sults that VxWorks has high stability and real time performance, ensuring accurate flight control and a smooth flight of the micro aerial vehicle.
基金Project supported by the Major State Basic Research Development Program of China (Grant Nos.2013CB329602 and 2012CB316303)the Science Research Foundation for the Returned Overseas Chinese Scholars,China (Grant No.2010-31)+1 种基金the International Collaborative Project of Shanxi Province,China (Grant No.2011081034)the National Natural Science Foundation of China (Grant Nos.61232010 and 61202215)
文摘Community detection methods have been used in computer, sociology, physics, biology, and brain information science areas. Many methods are based on the optimization of modularity. The algorithm proposed by Blondel et al. （Blondel V D, Guillaume J L, Lambiotte R and Lefebvre E 2008 J. Star. Mech. 10 10008） is one of the most widely used methods because of its good performance, especially in the big data era. In this paper we make some improvements to this algorithm in correctness and performance. By tests we see that different node orders bring different performances and different community structures. We find some node swings in different communities that influence the performance. So we design some strategies on the sweeping order of node to reduce the computing cost made by repetition swing. We introduce a new concept of overlapping degree （OV） that shows the strength of connection between nodes. Three improvement strategies are proposed that are based on constant OV, adaptive OV, and adaptive weighted OV, respectively. Experiments on synthetic datasets and real datasets are made, showing that our improved strategies can improve the performance and correctness.
基金supported in part by the National Natural Science Foundation of China under Grant No.61402521Jiangsu Province Natural Science Foundation of China under Grant No.BK20140068the China Post Doctoral Science Foundation under Grant No.2017M610286
文摘In the past decades, many cleanslate future network architectures have gained limited deployment in current Internet, due to the stability and rigidity of TCP/IP, the narrow waist of the Internet. We first propose three principles that the future Internet architecture should obey to be well-defined network architecture, i.e. supporting service innovation and enabling evolvability. By abstracting different modes from TCP/IP network and SDN technology, we argue that the centric-distributed-centric(CDC) mode has great potential for the well-defined future network architecture in which diverse network architectures could be incrementally deployed and coexist with each other. Prototype system regulated by CDC mode was developed. Experimental results reveal that CDC can support diverse architectures to coexist in the current Internet and thus enables the Internet to evolve.
基金funded by the key project of the National Natural Science Foundation of China (No.61431001)the National High-Tech R&D Program (863 Program 2015AA01A705)New Technology Star Plan of Beijing (No.xx2013052)
文摘In centralized cellular network architecture,the concept of virtualized Base Station(VBS) becomes attracting since it enables all base stations(BSs) to share computing resources in a dynamic manner. This can significantly improve the utilization efficiency of computing resources. In this paper,we study the computing resource allocation strategy for one VBS by considering the non-negligible effect of delay introduced by switches. Specifically,we formulate the VBS's sum computing rate maximization as a set optimization problem. To address this problem,we firstly propose a computing resource schedule algorithm,namely,weight before one-step-greedy(WBOSG),which has linear computation complexity and considerable performance. Then,OSG retreat(OSG-R) algorithm is developed to further improve the system performance at the expense of computational complexity. Simulation results under practical setting are provided to validate the proposed two algorithms.
基金Supported by the National Natural Science Foundation of China(61272119,61203372)
文摘A new centrality measure for complex networks, called resource flow centrality, is pro- posed in this paper. This centrality measure is based on the concept of the resource flow in net- works. It not only can be applied to the connected networks, but also the disconnected networks. Moreover, it overcomes some disadvantages of several common centrality measures. The perform- ance of the proposed measure is compared with some standard centrality measures using a classic dataset and the results indicate the proposed measure performs more reasonably. The statistical dis- tribution of the proposed centrality is investigated by experiments on large scale computer generated graphs and two networks from the real world.
基金funded by the National Basic Research Program of China ("973" Program) under Grant No. 2007CB310805the National High Technology Research and Development Program of China ("863" Program) under Grant No. 2007AA12Z309
文摘Cloud computing provides a new paradigm for hardware and software infrastructure design as well as planning and usage of information systems. It offers flexible, efficient, inexpensive, and quality services. This paper proposes an on-demand service system using the cloud computing architecture and analyzes important issues such as organization, management, and monitoring of distributed service resources; context-aware on-demand service modeling, on-demand automated service composition in large-scale networks, and service system analysis based on complex system theory. Continuous Operating Reference Station （CORS） of a geo-spatial information system is taken as an example, and its architecture is analyzed from the perspective of cloud computing. Some fundamental questions are raised about its service.
基金National Science and Technology Major Project of Ministry of Industry and Information Technology in 2011(2011ZX03003-003-02)
文摘In recent years,as China has finished the updating of the fourth generation of network,for guaranteeing the information security of the state,communication chip with complete independent intellectual property right must be possessed to support the advancement of such project.TD-LTE Baseband Chip is a super-large-scale integrated circuit designed basing on SOC,which needs to carry out coding,etc to the transmitted baseband signal,or carry out decoding,etc to the received baseband signal.LPDDR2 SDRAM is used in the chip design process due to its low power dissipation,high capacity and high reliability.As PHY in the controller architecture of LPDDR2 SDRAM adopts hard core design,it cannot be achieved in Virtex-7 2000T prototype verification platform.This design mainly builds on such prototype verification platform to propose the verification scheme of LPDDR2 SDRAM controller in TD_LTE baseband chip,so as to guarantee that prototype verification in FPGA can be carried out by TD_LTE baseband system,and meanwhile high capacity storage space can be provided to the system.
基金supported by Jiangsu Provincial Key Research and Development Program (No.BE20210132)the Zhejiang Provincial Key Research and Development Program (No.2021C01040)the team of S-SET
文摘Low-Earth-Orbit satellite constellation networks(LEO-SCN)can provide low-cost,largescale,flexible coverage wireless communication services.High dynamics and large topological sizes characterize LEO-SCN.Protocol development and application testing of LEO-SCN are challenging to carry out in a natural environment.Simulation platforms are a more effective means of technology demonstration.Currently available simulators have a single function and limited simulation scale.There needs to be a simulator for full-featured simulation.In this paper,we apply the parallel discrete-event simulation technique to the simulation of LEO-SCN to support large-scale complex system simulation at the packet level.To solve the problem that single-process programs cannot cope with complex simulations containing numerous entities,we propose a parallel mechanism and algorithms LP-NM and LP-YAWNS for synchronization.In the experiment,we use ns-3 to verify the acceleration ratio and efficiency of the above algorithms.The results show that our proposed mechanism can provide parallel simulation engine support for the LEO-SCN.
基金supported by National Natural Science Foundation of China with granted No.61404175
文摘As an important branch of information security algorithms,the efficient and flexible implementation of stream ciphers is vital.Existing implementation methods,such as FPGA,GPP and ASIC,provide a good support,but they could not achieve a better tradeoff between high speed processing and high flexibility.ASIC has fast processing speed,but its flexibility is poor,GPP has high flexibility,but the processing speed is slow,FPGA has high flexibility and processing speed,but the resource utilization is very low.This paper studies a stream cryptographic processor which can efficiently and flexibly implement a variety of stream cipher algorithms.By analyzing the structure model,processing characteristics and storage characteristics of stream ciphers,a reconfigurable stream cryptographic processor with special instructions based on VLIW is presented,which has separate/cluster storage structure and is oriented to stream cipher operations.The proposed instruction structure can effectively support stream cipher processing with multiple data bit widths,parallelism among stream cipher processing with different data bit widths,and parallelism among branch control and stream cipher processing with high instruction level parallelism;the designed separate/clustered special bit registers and general register heaps,key register heaps can satisfy cryptographic requirements.So the proposed processor not only flexibly accomplishes the combination of multiple basic stream cipher operations to finish stream cipher algorithms.It has been implemented with 0.18μm CMOS technology,the test results show that the frequency can reach 200 MHz,and power consumption is 310 mw.Ten kinds of stream ciphers were realized in the processor.The key stream generation throughput of Grain-80,W7,MICKEY,ACHTERBAHN and Shrink algorithm is 100 Mbps,66.67 Mbps,66.67 Mbps,50 Mbps and 800 Mbps,respectively.The test result shows that the processor presented can achieve good tradeoff between high performance and flexibility of stream ciphers.
