Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA stra...Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA strategy, which might not be suited to the dynamic network environment. In this paper, we propose a multi-strategy DSA(MS-DSA) system, where the primary and the secondary system share spectrum resources with multiple DSA strategies simultaneously. To analyze the performance of the proposed MS-DSA system, we model it as a continuous-time Markov chain(CTMC) and derive the expressions to compute the corresponding performance metrics. Based on this, we define a utility function involving the concerns of effective throughput, interference quantity on primary users, and spectrum leasing cost. Two optimization schemes, named as spectrum allocation and false alarm probability selection, are proposed to maximize the utility function. Finally, numerical simulations are provided to validate our analysis and demonstrate that the performance can be significantly improved caused by virtues of the proposed MS-DSA system.展开更多
5G is a new generation of mobile networking that aims to achieve unparalleled speed and performance. To accomplish this, three technologies, Device-to-Device communication (D2D), multi-access edge computing (MEC) and ...5G is a new generation of mobile networking that aims to achieve unparalleled speed and performance. To accomplish this, three technologies, Device-to-Device communication (D2D), multi-access edge computing (MEC) and network function virtualization (NFV) with ClickOS, have been a significant part of 5G, and this paper mainly discusses them. D2D enables direct communication between devices without the relay of base station. In 5G, a two-tier cellular network composed of traditional cellular network system and D2D is an efficient method for realizing high-speed communication. MEC unloads work from end devices and clouds platforms to widespread nodes, and connects the nodes together with outside devices and third-party providers, in order to diminish the overloading effect on any device caused by enormous applications and improve users’ quality of experience (QoE). There is also a NFV method in order to fulfill the 5G requirements. In this part, an optimized virtual machine for middle-boxes named ClickOS is introduced, and it is evaluated in several aspects. Some middle boxes are being implemented in the ClickOS and proved to have outstanding performances.展开更多
Access control in multi-domain environments is an important question in building coalition between domains. Based on the RBAC access control model and the concepts of secure domain, the role delegation and role mappin...Access control in multi-domain environments is an important question in building coalition between domains. Based on the RBAC access control model and the concepts of secure domain, the role delegation and role mapping are proposed, which support the third-party authorization. A distributed RBAC model is then presented. Finally implementation issues are discussed.展开更多
The truncated binary exponential back-off algorithm is one of the most effective methods applied in collision resolution process of random multi-access channel.In this study,two new strategies are presented to improve...The truncated binary exponential back-off algorithm is one of the most effective methods applied in collision resolution process of random multi-access channel.In this study,two new strategies are presented to improve the capability of the truncated binary exponential back-off algorithm.In the new strategies,the sizes of the initial window size or the operating window sizes are adjusted dynamically,which always bring a significant improvement for the self-adaptability of the original algorithm.A series of experiments are simulated and the results verify that the new strategies can make the implementation more stable and effective than the original algorithm.展开更多
MORPAS is a special GIS (geographic information system) software system, based on the MAPGIS platform whose aim is to prospect and evaluate mineral resources quantificationally by synthesizing geological, geophysical,...MORPAS is a special GIS (geographic information system) software system, based on the MAPGIS platform whose aim is to prospect and evaluate mineral resources quantificationally by synthesizing geological, geophysical, geochemical and remote sensing data. It overlays geological database management, geological background and geological abnormality analysis, image processing of remote sensing and comprehensive abnormality analysis, etc.. It puts forward an integrative solution for the application of GIS in basic-level units and the construction of information engineering in the geological field. As the popularization of computer networks and the request of data sharing, it is necessary to extend its functions in data management so that all its data files can be accessed in the network server. This paper utilizes some MAPGIS functions for the second development and ADO (access data object) technique to access multi-source geological data in SQL Server databases. Then remote visiting and congruous management will be realized in the MORPAS system.展开更多
The secure interaction among multiple security domains is a major concern. In this paper, we highlight the issues of secure interoperability among multiple security domains operating under the widely accepted Role Bas...The secure interaction among multiple security domains is a major concern. In this paper, we highlight the issues of secure interoperability among multiple security domains operating under the widely accepted Role Based Access Control （RBAC） model. We propose a model called CRBAC that easily establishes a global policy for roles mapping among multiple security domains. Our model is based on an extension of the RBAC model. Also, multiple security domains were composed to one abstract security domain. Also roles in the multiple domains are translated to permissions of roles in the abstract security domain. These permissions keep theirs hierarchies. The roles in the abstract security domain implement roles mapping among the multiple security domains. Then, authorized users of any security domain can transparently access resources in the multiple domains.展开更多
张量转置(tensor transposition)作为基础张量运算原语,广泛应用于信号处理、科学计算以及深度学习等各种领域,在张量数据密集型应用及高性能计算中具有重要作用。随着能效指标在高性能计算系统中的重要性日益凸显,基于数字信号处理器(d...张量转置(tensor transposition)作为基础张量运算原语,广泛应用于信号处理、科学计算以及深度学习等各种领域,在张量数据密集型应用及高性能计算中具有重要作用。随着能效指标在高性能计算系统中的重要性日益凸显,基于数字信号处理器(digital signal processors,DSPs)的加速器已被集成至通用计算系统。然而,传统面向多核CPU和GPU的张量转置库因架构差异无法充分适配DSP架构。一方面,DSP架构的向量化计算潜力尚未得到充分挖掘;另一方面,其复杂的片上存储体系与多层次共享内存结构为张量并行程序设计带来了显著挑战。针对国产多核DSP的架构特点,提出ftmTT算法,并设计实现了一个面向多核DSP架构的通用张量转置库。ftmTT算法通过设计适配DSP架构的高效内存访问模式充分挖掘其并行化和向量化潜力,其核心创新包括:1)采用分块策略将高维张量转置转化为多核DSP平台所提供的矩阵转置内核操作;2)提出基于DMA点对点传输的张量数据块访存合并方案来降低数据搬运开销;3)通过双缓冲设计异步重叠转置计算与DMA传输实现计算通信隐藏,最终面向多核DSP实现高性能并行张量转置。在国产多核DSP平台FT-M7032的实验表明,ftmTT张量转置算法取得了最高达理论带宽75.96%的性能,达到FT-M7032平台STREAM带宽99.23%的性能。展开更多
高性能同轴电缆网络(High Performance Network Over Coax,HINOC)技术是一种光纤同轴混合接入技术,已发展至第3代。为了实现万兆以太网的接入速率,第3代HINOC引入了多信道绑定机制。但该机制在有效扩展HINOC网络信道带宽的同时易导致HIM...高性能同轴电缆网络(High Performance Network Over Coax,HINOC)技术是一种光纤同轴混合接入技术,已发展至第3代。为了实现万兆以太网的接入速率,第3代HINOC引入了多信道绑定机制。但该机制在有效扩展HINOC网络信道带宽的同时易导致HIMAC(HINOC Medium Access Control)拆帧端接收的数据流失序。针对该问题,文中提出了一种拆帧重排序方法。通过重排序队列缓存管理、入队逻辑地址计算、超时判断及清空以及出队判断等关键技术的设计和实现来解决多信道绑定机制引起的拆帧乱序问题,并对其关键功能点进行仿真验证和板级验证。实验结果表明,所提方法能够有效处理多信道绑定导致的乱序问题,并且能够确保系统在遇到错误情况时稳定运行,具有较强的鲁棒性,满足万兆同轴宽带接入HIMAC 3.0的功能和性能要求。展开更多
基金supported in part by the National Natural Sciences Foundation of China (NSFC) under Grant 61525103the National Natural Sciences Foundation of China under Grant 61501140the Shenzhen Fundamental Research Project under Grant JCYJ20150930150304185
文摘Dynamic spectrum access(DSA) based on cognitive radios(CR) technique is an effective approach to address the "spectrum scarcity" issue. However, traditional CR-enabled DSA system employs only single DSA strategy, which might not be suited to the dynamic network environment. In this paper, we propose a multi-strategy DSA(MS-DSA) system, where the primary and the secondary system share spectrum resources with multiple DSA strategies simultaneously. To analyze the performance of the proposed MS-DSA system, we model it as a continuous-time Markov chain(CTMC) and derive the expressions to compute the corresponding performance metrics. Based on this, we define a utility function involving the concerns of effective throughput, interference quantity on primary users, and spectrum leasing cost. Two optimization schemes, named as spectrum allocation and false alarm probability selection, are proposed to maximize the utility function. Finally, numerical simulations are provided to validate our analysis and demonstrate that the performance can be significantly improved caused by virtues of the proposed MS-DSA system.
文摘5G is a new generation of mobile networking that aims to achieve unparalleled speed and performance. To accomplish this, three technologies, Device-to-Device communication (D2D), multi-access edge computing (MEC) and network function virtualization (NFV) with ClickOS, have been a significant part of 5G, and this paper mainly discusses them. D2D enables direct communication between devices without the relay of base station. In 5G, a two-tier cellular network composed of traditional cellular network system and D2D is an efficient method for realizing high-speed communication. MEC unloads work from end devices and clouds platforms to widespread nodes, and connects the nodes together with outside devices and third-party providers, in order to diminish the overloading effect on any device caused by enormous applications and improve users’ quality of experience (QoE). There is also a NFV method in order to fulfill the 5G requirements. In this part, an optimized virtual machine for middle-boxes named ClickOS is introduced, and it is evaluated in several aspects. Some middle boxes are being implemented in the ClickOS and proved to have outstanding performances.
文摘Access control in multi-domain environments is an important question in building coalition between domains. Based on the RBAC access control model and the concepts of secure domain, the role delegation and role mapping are proposed, which support the third-party authorization. A distributed RBAC model is then presented. Finally implementation issues are discussed.
基金This work was supported by the National Natural Science Foundation of China(No.10371097).
文摘The truncated binary exponential back-off algorithm is one of the most effective methods applied in collision resolution process of random multi-access channel.In this study,two new strategies are presented to improve the capability of the truncated binary exponential back-off algorithm.In the new strategies,the sizes of the initial window size or the operating window sizes are adjusted dynamically,which always bring a significant improvement for the self-adaptability of the original algorithm.A series of experiments are simulated and the results verify that the new strategies can make the implementation more stable and effective than the original algorithm.
文摘MORPAS is a special GIS (geographic information system) software system, based on the MAPGIS platform whose aim is to prospect and evaluate mineral resources quantificationally by synthesizing geological, geophysical, geochemical and remote sensing data. It overlays geological database management, geological background and geological abnormality analysis, image processing of remote sensing and comprehensive abnormality analysis, etc.. It puts forward an integrative solution for the application of GIS in basic-level units and the construction of information engineering in the geological field. As the popularization of computer networks and the request of data sharing, it is necessary to extend its functions in data management so that all its data files can be accessed in the network server. This paper utilizes some MAPGIS functions for the second development and ADO (access data object) technique to access multi-source geological data in SQL Server databases. Then remote visiting and congruous management will be realized in the MORPAS system.
基金Supported by the National Natural Science Foun-dation of China(60403027) the Natural Science Foundation of HubeiProvince(2005ABA258) the Open Foundation of State Key Labo-ratory of Software Engineering(SKLSE05-07)
文摘The secure interaction among multiple security domains is a major concern. In this paper, we highlight the issues of secure interoperability among multiple security domains operating under the widely accepted Role Based Access Control （RBAC） model. We propose a model called CRBAC that easily establishes a global policy for roles mapping among multiple security domains. Our model is based on an extension of the RBAC model. Also, multiple security domains were composed to one abstract security domain. Also roles in the multiple domains are translated to permissions of roles in the abstract security domain. These permissions keep theirs hierarchies. The roles in the abstract security domain implement roles mapping among the multiple security domains. Then, authorized users of any security domain can transparently access resources in the multiple domains.
文摘张量转置(tensor transposition)作为基础张量运算原语,广泛应用于信号处理、科学计算以及深度学习等各种领域,在张量数据密集型应用及高性能计算中具有重要作用。随着能效指标在高性能计算系统中的重要性日益凸显,基于数字信号处理器(digital signal processors,DSPs)的加速器已被集成至通用计算系统。然而,传统面向多核CPU和GPU的张量转置库因架构差异无法充分适配DSP架构。一方面,DSP架构的向量化计算潜力尚未得到充分挖掘;另一方面,其复杂的片上存储体系与多层次共享内存结构为张量并行程序设计带来了显著挑战。针对国产多核DSP的架构特点,提出ftmTT算法,并设计实现了一个面向多核DSP架构的通用张量转置库。ftmTT算法通过设计适配DSP架构的高效内存访问模式充分挖掘其并行化和向量化潜力,其核心创新包括:1)采用分块策略将高维张量转置转化为多核DSP平台所提供的矩阵转置内核操作;2)提出基于DMA点对点传输的张量数据块访存合并方案来降低数据搬运开销;3)通过双缓冲设计异步重叠转置计算与DMA传输实现计算通信隐藏,最终面向多核DSP实现高性能并行张量转置。在国产多核DSP平台FT-M7032的实验表明,ftmTT张量转置算法取得了最高达理论带宽75.96%的性能,达到FT-M7032平台STREAM带宽99.23%的性能。
文摘高性能同轴电缆网络(High Performance Network Over Coax,HINOC)技术是一种光纤同轴混合接入技术,已发展至第3代。为了实现万兆以太网的接入速率,第3代HINOC引入了多信道绑定机制。但该机制在有效扩展HINOC网络信道带宽的同时易导致HIMAC(HINOC Medium Access Control)拆帧端接收的数据流失序。针对该问题,文中提出了一种拆帧重排序方法。通过重排序队列缓存管理、入队逻辑地址计算、超时判断及清空以及出队判断等关键技术的设计和实现来解决多信道绑定机制引起的拆帧乱序问题,并对其关键功能点进行仿真验证和板级验证。实验结果表明,所提方法能够有效处理多信道绑定导致的乱序问题,并且能够确保系统在遇到错误情况时稳定运行,具有较强的鲁棒性,满足万兆同轴宽带接入HIMAC 3.0的功能和性能要求。
