A trustworthy agent-based encrypted access control method for mobile cloud computing environment

To strengthen the security of access control protocols for mobile cloud environment, dynamic attributes of mobile devices are used. The weak or disconnection issue of the mobile network is a critical task to deal with. The proposed approach provides access control as well as data confidentiality using dynamic attributes encryption. The pairs of mobile agents are used to deal with the issue of network connection. The secret key is distributed using the anonymous key-issuing protocol which preserves the anonymity of the user. The approach is implemented in a real mobile cloud environment, and the performance under various parameters is evaluated.     

基于AHP的分布式星群接入策略研究

分布式星群网络是打赢未来信息化战争的有利武器,星群的接入技术对于提升我国空天信息获取能力具有重要意义。针对分布式星群网络高动态拓扑导致资源利用不充分的问题,提出了一种基于层次分析法的分布式星群网络接入策略。该接入策略首先是利用层次分析法动态计算资源利用率各指标权重;其次是根据各卫星节点的实时资源情况,动态调整资源利用率的权重。仿真表明,该接入策略降低了分布式星群网络的新呼叫阻塞率和强制中断率,有效地解决了星群网络资源利用率问题,提高了星群网络群内业务分配的合理性。     

基于VxLAN的网络分组策略研究与分析

IP网络接入的终端数量和种类越来越多(如企业员工PC或TC接入、访客手机接入、IP Phone/打印机/物联终端等接入)、承载的业务类型日益丰富,例如企业办公网、生产网、视频监控网、智能楼宇物联网等统一到IP网络上承载,员工接入方式也多种多样,如公司分支机构或总部接入、出差远程VPN接入等,传统基于ACL的网络策略无法应对企业IP网络业务场景的变化,面临管理维护复杂度的重要挑战。该文给出一种基于用户逻辑分组(安全组)的策略模型,并全面分析企业应用场景,给出基于VxLAN网络的安全组全网同步方案,实现网络策略与网络属性(IP/VLAN/MAC)等无关,大大降低企业IP网络策略数量和变更频率,并在实际大型企业的IT网络进行应用评估,可以将数以万计的策略数量降低到百计,应用价值高、效果明显,指明了企业IP网络策略的演进方向。     

一种嵌入式设备网络接口模块的设计与实现

采用单片机加上网络接口芯片组建一种网络接口模块,对模块的网络接口芯片编写驱动程序,并选择uIP这种开源的极小TCP/IP协议栈作为网络通信协议.对uIP协议栈的内核函数进行适当的配置和修改,将其移植到网络接口模块中.使用该模块能实现低端嵌入式设备的网络接人.     

宽带接入网技术发展浅析

随着骨干网速度的快速提升,各种宽带接入技术开始涌现。目前常见的接入技术有XDSL、Cable Modem、以太网接入、无线接入和光纤接入等技术;这些接入技术各有各自的特点和不足;其中,宽带固定无线接入技术较为适应目前宽带接入的发展趋势和需求。     

Optimal linear estimation for networked systems with communication constraints

This paper is concerned with the optimal linear estimation problem for discrete time-varying networked systems with communication constraints. The communication constraint considered is that only one network node is allowed to gain access to a shared communication channel, then the various network nodes of the networked systems are scheduled to transmit data according to a specified media access control protocol, and a remote estimator performs the estimation task with only partially available measurements. The channel accessing processes of those network nodes are modeled by Bernoulli processes, and optimal linear filters are designed by using the orthogonal projection principle and the innovation analysis approach. It is shown that the optimal estimation performances critically depend on the channel accessing probabilities of the network nodes and the packet loss probability, and the optimal filters can be obtained by solving recursive Lyapunov and Riccati equations. An illustrative example is finally given to show the effectiveness of the proposed filters.     

Multi-period design of survivable wireless access networks under capacity constraints

Design of survivable wireless access networks plays a key role in the overall design of a wireless network. In this research, the multi-period design of a wireless access network under capacity and survivability constraints is considered. Given the location of the cells and hubs, the cost of interconnection, and the demands generated by the cells, the goal of the designer is to find the best interconnection between cells and hubs so that the overall connection cost is minimized and the capacity and the survivability constraints are met. Integer programming formulations for this problem are proposed and the problems are solved using heuristic methods. Using different combination of network sizes, demand patterns and various time periods, a number of numerical experiments are conducted and all of them are found to yield high quality solutions.     

网络存储系统中多协议数据共享一致性问题的研究

网络的开放性和数据存储服务功能的多样性,使得网络存储设备必须使用多套数据访问协议为不同系统平台的客户端提供多样化的存储服务。如何确保使用不同协议共享网络存储设备的各个客户端能协同工作,也即保证多协议数据共享的一致性成为存储领域的一项关键技术和学术热点。文章系统地分析了网络数据共享中的同步和一致性问题,并提出了一套可扩展的分层式锁管理(ExtensibleHierarchicLockManagement)的解决方案。     

对等网络安全访问控制方案

提出一个安全对等访问控制方案,该方案采用两层访问控制策略：一层主要对成员资格进行审核,屏蔽一些不符合对等网络安全要求的成员;另一层基于可信值的访问控制策略,对进入对等网络后的成员行为进行评估,根据评估的可信值来决定赋予该成员访问网络资源的权限。当发现恶意成员时,网络能废除这些成员,实现对等网络的安全访问控制。     

A per-application mobility management platform for application-specific handover decision in overlay networks

With the advance of various wireless access technologies, the demand for a mobile user equipped with multiple air interfaces simultaneously executing diverse applications emerged. In such network environments, per-application mobility management is a key to allow each application of an end user device to dynamically and fully take advantage of the most suitable access technology. In this paper, we devised a comprehensive architectural platform with cross-layer techniques to realize this disruptive technology, i.e., per-application mobility management. The proposed platform enables the triggering of vertical handover decisions based on the dynamic measurements from the entire protocol stack. For per-application, the handover decision as well as the mobility management and the transport/application protocol control adaptation for handover performance optimization are made with cross-layer techniques. Through the simulation results, it is shown that multi-layer handover triggering of the proposed platform enhances the QoS of the application services by making handover decisions when the QoS requirements of an application is not satisfied as well as when a mobile user moves out of the current access network in overlay network environments. It is also presented that per-application handover based on the proposed platform enhances the QoS of the application services compared to the handover approaches which make every on-going service flows handover together to the same access network.     

CSMA/CD with network partitioning

One of the local area network medium access control standards created by the Institute of Electrical and Electronic Engineers in IEEE Project 802 is the carrier sense multiple access with collision detection (CSMA/CD. These studies show that control. Numerous studies have been reported in the literature on the performance of CSMA/CD. These studies show that CSMA/CD performs well under light network load but not well at heavy load. To improve the performance of CSMA/CD under heavy load, a new concept called network partitioning is presented. Network partitioning allows the network to be partitioned into segments when under heavy load. Partition stations then act as bridges between the segments. The impact of network partitioning on network performance was tested using a simulation model of an Ethernet local area network (an implementation of the CSMA/CD medium access control). The simulation results show that network partitioning can significantly improve the performance of CSMA/CD under heavy load.     

Performance evaluation of circuit switched multistageinterconnection networks using a hold strategy

The performance evaluation of processor-memory communications for multiprocessor systems using circuit switched interconnection networks with a hold strategy is performed. Message size and processor processing time are considered and shown to have a significant effect on the overall system performance. A closed queuing network model is proposed such that only (n+2) states are required by the proposed model, in contrast to (n²+3n+4)/2 states needed in previous studies, where n is the number of stages of the multistage interconnection network. Since a closed-form solution is obtained, the behavior of a complete cycle of memory access through multistage interconnection networks can be accurately analyzed and various performance bounds can be obtained     

一个多功能路由查找引擎的设计与实现

针对网络边缘和接入层设备需处理多种网络协议和价格敏感的特点,文中介绍了一种能支持精确匹配和最长前缀匹配的多功能查找引擎。此引擎以五级环行多功能流水线为核心,通过SRAM接口与主机交互,采用ZBTSRAM作为路由表存储器。文中着重介绍了引擎的硬件结构、软件系统和软硬件联合验证方法。性能评测表明,基于FPGA的实现主频可达到50MHz,性能可以满足1Gbps￣2Gbps的接入和边缘层设备要求。     

新一代接入网UA5000的测试分析

直接面对广大用户和各种应用系统的接入网是完成语音、数据、图像等综合业务的必经之路,它的质量和性能直接影响电信网的发展。文中重点对新一代接入网uA5000进行了测试分析,并对设备的优缺点进行了点评。     

利用SDN实现可编程无线局域网多径接入管理

WiFi接入点（Access Point,AP）被广泛部署在学校、商场和机场等公共场所,满足用户随时随地的使用需求.然而,管理大规模的WiFi网络仍是一个亟待解决的难题,设备间的差异性造成难以在无线局域网中提供集中的接入管理.同时,由于各种新服务、新应用的推动,使得传统无线局域网中的网络资源利用率低及接入点负载不均衡的问题目益严重.因此,本文引入SDN思想,将协议无关转发（POF）技术应用到无线局域网中,提出一种深度可编程无线局域网架构,实现集中接入管理.同时,综合考虑信号强度（RSSI）、实时网络流量等因素,提出一种基于多路径TCP （MultiPath TCP,MPTCP）的无线AP接入管理机制,充分利用各AP的带宽资源,避免在拥塞的路径上继续传输数据,从而均衡底层AP负载.     

基于功率优化的Ad hoc网络定向媒质接入控制

由于无线Ad hoc网络是一种由移动终端组成、网络拓扑结构动态变化的对等、自组织、多跳网络,使得传输带宽、传输功率成为具有挑战性的任务之一。分析了目前通常采用的信道接入技术(如：全向天线;CSMA／CA和洪泛)及存在的问题;在此基础上,为保证有效利用传输带宽,提高功率利用率,给出了用于定向天线的MAC的解决方案(简称DMAC)。节点通过虚拟载波侦听来重定向,实现定向传输,使功率得到优化。     

架设小型商业办公无线网络

对于很多中小企业的各种办公室来说,如何快速安全地组建网络,接入Internet,跨入信息化之门,是其迫切需要解决的问题。如果采用传统的交换机或集线器组成的星型有线网络,虽然硬件成本较低,但布设难度较大。要实现网络到桌面,繁杂的网络布线和工位布局让人头痛。如果采用无线组网技术,就能解决布线问题,并且还能提高工作效率。     

同步令牌通信方式及其扩展应用

本文提出一种新的网络访问方式。它引入了同步时钟和令牌链，使得各点可共享一条通信数据线而访问控制电路却简单到仅用几个Ｄ触发器即可实现。它具有传统令牌方式所没有的一些优点。在通信量较少，速度要求不高的场合，其效果很好。文中讨论的一种应用方式。     

通过K-means算法实现神经网络的加速和压缩

近年来,以神经网络为代表的机器学习领域快速发展,已广泛地应用于语音识别和图像识别等各个工业领域。随着应用环境越来越复杂,精度要求越来越高,网络规模也越来越大。大规模神经网络既是计算密集型又是存储密集型结构,其中卷积层是计算密集型层次,全连接层是存储密集型层次。前者的处理速度跟不上存取速度,后者的存取速度跟不上处理速度。基于神经网络本身训练的预测准确率置信区间,提出了一种使用K-means加速和压缩神经网络的方法。通过将卷积过程中的输入特征图采用K-means压缩来减少计算量;通过将全连接层的权重压缩来减少存储量。所提方法对AlexNet网络单个卷积层的计算量最多能降低2个数量级,加入合适的K-means层,整个网络的处理时间加速比能达到2.077,对网络压缩率达到8.7%。     

基于以太网的分布式智能门禁系统

对现有多种传统门禁系统进行了研究,发现其多采用RS485传输方式,具有控制范围小和布线繁琐等局限性.为构建大规模跨地域的门禁管理系统,采用将以太网技术与传统门禁系统相结合的方法及软硬件协同设计的思想,研制出了一种模块化可裁减、基于以太网的分布式智能控制门禁系统.实践证明,该系统控制范围大且利用现有发达的网络,不必重新布线,可有效实现远程门禁控制.对系统的整体结构和各部分的工作原理进行了详细的说明.