内容中心网络中能效感知的概率性缓存机制

内置缓存技术是内容中心网络(Content Centric Networking, CCN)的核心技术之一。现有的研究大多主要针对网络资源利用率的优化,而忽略了网络能耗的问题。该文首先建立了一个能耗模型对CCN的网络能耗进行分析,并设计了一个能效判决条件来优化缓存过程的能效性。进而,在此基础上综合考虑内容流行度和节点中心性等因素提出一种能效感知的概率性缓存机制(E2APC)。仿真结果表明,该机制能在保证较高的缓存命中率和较小的平均响应跳数的同时有效地降低网络的整体能耗。     

CCN网络中一种基于代理主动缓存的用户移动性支持方案

该文提出以内容为中心的网络(CCN)中一种基于代理的主动缓存方案。通过代理服务器主动请求与缓存移动切换过程中用户未能获取的内容,解决CCN网络中用户移动性支持问题。与现有CCN网络用户移动性支持方案相比,该文提出的基于代理的主动缓存方案,用户获取内容的时间成本与代理服务器获取内容的时间成本较低,用户的移动切换时延与内容获取的平均时间较短。该方案可有效利用CCN网络共享的内容资源,减缓用户移动对实时业务的不良影响。     

内容中心网络中基于差异化缓存通告的混合路由机制

针对内容中心网络(CCN)节点暂态缓存的高效利用问题,将数据场的思想引入到CCN转发决策中,该文提出一种基于差异化缓存通告的混合路由机制。缓存通告时,依据内容活跃等级和缓存驻留概率,执行差异化的内容通告和势能辐射;路由查找时,针对持久稳定的内容源和动态可变的临时缓存副本,分别构建全局导向和局域吸引势能辐射场,实现兴趣包请求的全局路由和局部就近应答。仿真结果表明,该机制减小了内容请求时延,提高了缓存命中率,以少量额外的开销提升了CCN网络整体的内容分发性能。     

内容中心网络中基于内容迁移的协作缓存机制

内容中心网络(CCN)是为了适应未来网络通信模式的转变,提供对可扩展和高效内容获取的原生支持而提出一种新型的网络体系架构,内容缓存机制是其研究的关键问题之一。现有机制在缓存节点的选择时往往过于集中,缓存负载分布严重不均,大大降低了网络资源利用率以及系统的缓存性能。该文提出一种基于缓存迁移的协作缓存机制,首先在缓存节点选择时考虑节点的中心性保证内容尽可能缓存在位置更重要的节点。同时,在缓存压力过大时,通过可用缓存空间大小、缓存替换率以及网络连接的稳定性等信息选择合适的邻居节点进行缓存内容的转移,充分利用邻居资源实现负载分担。仿真结果表明该机制能有效地改善缓存负载在节点上分布的均衡性,提高缓存命中率和缓存资源利用率并降低平均接入代价。     

Design of in-network caching scheme in CCN based on grey relational analysis

In-network caching is one of the most important issues in content centric networking （CCN）, which may extremely influence the performance of the caching system. Although much work has been done for in-network caching scheme design in CCN, most of them have not addressed the multiple network attribute parameters jointly during caching algorithm design. Hence, to fill this gap, a new in-network caching based on grey relational analysis （GRA） is proposed. The authors firstly define two newly metric parameters named request influence degree （RID） and cache replacement rate, respectively. The RID indicates the importance of one node along the content delivery path from the view of the interest packets arriving The cache replacement rate is used to denote the caching load of the node. Then combining hops a request traveling from the users and the node traffic, four network attribute parameters are considered during the in-network caching algorithm design. Based on these four network parameters, a GRA based in-network caching algorithm is proposed, which can significantly improve the performance of CCN. Finally, extensive simulation based on ndnSIM is demonstrated that the GRA-based caching scheme can achieve the lower load in the source server and the less average hops than the existing the betweeness （Betw） scheme and the ALWAYS scheme.     

NDN中路由机制研究综述

命名数据网络（NDN）是未来互联网研究中一个具有代表性的结构。着重介绍NDN中一些路由策略,其中涉及NDN的基本结构及转发机制、现有路由策略的发展及优缺点,最后提出了路由机制方面进一步的研究方向。     

一种基于层次路由推送的CCN移动性支持方案

随着互联网的快速发展,用户对内容信息的需求日趋明显,当前网络架构的设计已经不能满足时下服务的要求,因此,以信息为中心的未来网络的研究得以迅速发展.内容中心网络（CCN）是未来网络的研究热点之一,然而现阶段CCN的设计未深入考虑用户移动性问题.本文针对CCN网络中的移动性管理问题,提出一种基于层次路由推送的解决方案.仿真结果表明,本文所提出的方法能有效降低用户获取内容的时间及网络中消息重传数目.     

In-network caching for energy efficiency in content-centric networking

Recently, Internet energy efficiency is paid more and more attention. New Internet architectures with more energy efficiency were proposed to promote the scalability in energy consumption. The eontent-eentrie networking （CCN） proposed a content-centric paradigm which was proven to have higher energy efficiency. Based on the energy optimization model of CCN with in-network caching, the authors derive expressions to tradeoff the caching energy and the transport energy, and then design a new energy efficiency cache scheme based on virtual round trip time （EV） in CCN. Simulation results show that the EV scheme is better than the least recently used （LRU） and popularity based cache policies on the network average energy consumption, and its average hop is also much better than LRU policy.     

一种内容中心网络传输内容冗余的消除方法

为了减少互联网中传输数据包的大量冗余信息,减少网络流量,提高网络带宽利用效率,研究利用内容中心网络特殊的通信方式及路由器的内容缓存能力,提出一种内容中心网络(CCN)中网络级的传输内容冗余消除方法,在CCN中实现网络级的传输内容冗余消除。并通过仿真分析,验证了该方法可以有效地减少CCN网络中的流量。     

Effects of Unequal Couplings on Fidelity of a Quantum Controlled-Controlled-Not Gate

By numerically solving the Sch6dinger equation of a three-nuclear-spin system, the effects of the non-uniform nearest-neighbor （NN） interaction on the fidelity of a quantum controlled-controlled-no （CCN） gate are investigated for a digital initial state and a superposition initial state respectively. It is found from our simulation that the ratio of the deviation of the NN coupling δJ to the NN coupling J should be smaller than 0.0005 to ensure a high fidelity of the quantum CCN gate.