COD: caching on demand in information-centric networking

By overcoming the well-known challenges of the current internet, great expectations are focused on information-centric networking (ICN). ICN extensively uses universal in-network caching. However, developing an efficient caching scheme remains an open question. To overcome the useless caching and duplication caching of previous caching schemes, we propose an adaptive caching scheme—caching on demand (COD). By following the change in potential demand from the consumer and the temporal patterns of content popularity, COD allows content to be cached only by some necessary nodes instead of all nodes on the path from content provider to content consumer. At the same time, in accordance with trading off bandwidth for cache (bandwidth-for-cache), content can be pushed to the adjacent node with more cache capacity. We present a theoretical model to evaluate cache usage for COD. Finally, we evaluate COD through extensive experiments and a wide range of performance metrics. The experimental results under diverse setting demonstrate that COD can yield a steady improvement of network performance and caching efficiency compared with CEE, EgoBetw and Probcache. Notably, COD improves performance with negligible overhead.     

Internet-scale content mediation in information-centric networks

Given that the vast majority of Internet interactions relate to content access and delivery, recent research has pointed to a potential paradigm shift from the current host-centric Internet model to an information-centric one. In information-centric networks, named content is accessed directly, with the best content copy delivered to the requesting user given content caching within the network. Here, we present an Internet-scale mediation approach for content access and delivery that supports content and network mediation. Content characteristics, server load, and network distance are taken into account in order to locate the best content copy and optimize network utilization while maximizing the user quality of experience. The content mediation infrastructure is provided by Internet service providers in a cooperative fashion, with both decoupled/two-phase and coupled/one-phase modes of operation. We present in detail the coupled mode of operation which is used for popular content and follows a domain-level hop-by-hop content resolution approach to optimally identify the best content copy. We also discuss key aspects of our content mediation approach, including incremental deployment issues and scalability. While presenting our approach, we also take the opportunity to explain key information-centric networking concepts.     

Modeling in-network caching and bandwidth sharing performance in information-centric networking

Information-centric networking (ICN) proposes a content-centric paradigm which has some attractive advantages, such as network load reduction, low dissemination latency, and energy efficiency. In this paper, based on the analytical model of ICN with receiver-driven transport protocol employing least-recently used (LRU) replacement policy, we derive expressions to compute the average content delivery time of the requests' arrival sequence of a single cache, and then we extend the expressions to a cascade of caches’ scenario. From the expressions, we know the quantitative relationship among the delivery time, cache size and bandwidth. Our results, analyzing the trade-offs between performance and resources in ICN, can be used as a guide to design ICN and to evaluation its performance.     

机会传感器网络中基于优先级的查询分发和处理算法

提出了机会无线传感器网络中一种基于查询优先级的查询分发和处理(PBQ)算法。算法根据用户定义的查询优先级合理选取消息转发的中间节点,并控制查询消息的转发和拷贝量;同时,动态地调整查询消息的优先级,使得查询结果能快速回传到查询发起者并清理网络中查询的残留消息,避免了不必要的消息传输并提高查询处理的整体效用。模拟实验表明PBQ算法能有效提高机会网络中查询处理的成功率,降低查询的开销和时间延迟。     

Reverse-trace routing scheme in content centric networking

Content center networking （CCN） is one of the most promising future network architectures. Current researches on CCN routing scheme mainly focus on finding the best single routing path, which may induce to low usage of the in-network caches. In order to overcome this problem, a reverse trace routing （RTR） scheme is proposed in this paper, in which Interest packet is sent to the edge-cache along with the reverse trace of the corresponding former Data packet. By doing this, the Interest packets will have better chances to be routed to the promising in-network caches before reaching the source server, which could increase the in-network hit rate, while decrease the server stress. The simulation results show clearly that the RTR scheme decreases the source server load, while reducing the mean hops of entire data retrieval process under certain circumstances.     

Modeling chunk-based content placement in information centric networking

Content-centric networking (CCN) proposes a content-centric paradigm which changes the waist hourglass from Internet protocol (IP) to content chunk. In this paper, based on content chunks, an optimization model of minimizing the total delay time in information centric networking (ICN) is established, and branch-and-bound method and greedy (BG) algorithm is proposed to get the content placement method. As the multipath is natural supported in CCN, chunk-based content placement can decline delay time obviously, even it would increase the calculation amount which can be solved easily by the node's capacity. Simulation results indicate that the chunk-based content placement scheme is better than the single-based cache policy on the network total delay time, and the best number of each content chunk split is decided by the link density and the number of the nodes in the network.     

内容中心网络缓存隐私保护策略

缓存隐私泄露是内容中心网络中的重要安全威胁之一,攻击者通过探测缓存可以获取合法用户的隐私信息。针对该安全问题,在隐私与非隐私内容区分的基础上,提出一种基于最近访问信息与回退机制的缓存隐私保护策略（CPPS-RVI&ECP）,并与现有典型防御策略-随机k延迟（RFKD）对比,围绕隐私泄露率与网络命中率开展理论性能分析。该策略通过设置隐私标识,实现最近访问者的识别;通过随机缓存位置存入以及移出回退机制,降低了隐私泄露概率,且提升了网络性能。设定实验条件进行数值分析,结果表明,虽然RFKD有理想的隐私保护能力,但是它是以完全牺牲缓存的内容分发能力为代价的,而CPPS-RVI&ECP则通过合理设置回退概率,可以在保持较低隐私泄露率的同时,获得较高的网络命中率。     

A popularity based content eviction scheme via betweenness-centrality caching approach for content-centric networking (CCN)

Wireless Networks - In distinction to today’s IP-based, host-bound, Internet architecture, content-centric networking (CCN) emphasizes content by making it instantly addressable and routable....     

The interplay between signal processing and networking in sensor networks

This paper provides a signal processing perspective on large-scale sensor networks. It focuses on two characteristics of sensor networks: application specificity and energy constraint. The former requires that network protocols be designed for the application at hand, which is often signal processing in nature, and measured by application-specific metrics. The latter calls for novel distributed signal processing techniques to provide accurate and timely network state information that can be exploited by network protocols to ensure energy efficiency. The underlying theme is about how a principled integration of signal processing and networking can lead to an efficient and fair use of limited resources. The paper aims to demonstrate that capturing and exploiting dependencies between signal processing and networking offer design choices resulting in improved network performance.     

时间敏感网络（TSN）及无线TSN技术

时间敏感网络（TSN）在以太网的基础上提供端到端极低时延和高可靠性的数据传输,适用于时延敏感型应用,广泛应用于自动驾驶、工业互联网等场景。首先总结了TSN的特点,并详细阐述了TSN标准的工作原理和特性,重点介绍了在无线网络中提供确定性时延和可靠数据传输的网络技术,即无线TSN技术。此外,通过TSN的应用场景简要分析了TSN的应用案例。最后探讨了TSN和无线TSN技术及其在工业场景中应用存在的挑战和问题,并展望了未来的研究方向。     

ENROUTE: An Entropy Aware Routing Scheme for Information-Centric Networks (ICN)

With the exponential growth of end users and web data, the internet is undergoing the change of paradigm from a user-centric model to a content-centric one, popularly known as information-centric networks (ICN). Current ICN research evolves around three key-issues namely (i) content request searching, (ii) content routing, and (iii) in-network caching scheme to deliver the requested content to the end user. This would improve the user experience to obtain requested content because it lowers the download delay and provides higher throughput. Existing researches have mainly focused on on-path congestion or expected delivery time of a content to determine the optimized path towards custodian. However, it ignores the cumulative effect of the link-state parameters and the state of the cache, and consequently it leads to degrade the delay performance. In order to overcome this shortfall, we consider both the congestion of a link and the state of on-path caches to determine the best possible routes. We introduce a generic term entropy to quantify the effects of link congestion and state of on-path caches. Thereafter, we develop a novel entropy dependent algorithm namely ENROUTE for searching of content request triggered by any user, routing of this content, and caching for the delivery this requested content to the user. The entropy value of an intra-domain node indicates how many popular contents are already cached in the node, which, in turn, signifies the degree of enrichment of that node with the popular contents. On the other hand, the entropy for a link indicates how much the link is congested with the traversal of contents. In order to have reduced delay, we enhance the entropy of caches in nodes, and also use path with low entropy for downloading contents. We evaluate the performance of our proposed ENROUTE algorithm against state-of-the-art schemes for various network parameters and observe an improvement of 29–52% in delay, 12–39% in hit rate, and 4–39% in throughput.

     

A novel networking architecture for mobile content delivery in urban transport systems

Today, the media content delivery in intermittent connected networks has become increasingly critical. This paper studies content exchange among mobile commuters in urban transport systems. Our work is inspired by two facts: (1) the commuters in urban transport systems tend to take regular routes to the same place every weekday and their paths exhibit a high degree of temporal and spatial regularities; (2) the rapid development of broadband wireless technologies such as IEEE 802.11n makes fast data transfer possible. We first propose a new disconnection-tolerant network infrastructure, which reinforces the connectivity of intermittent connected mobile commuters and uses store-and-forward routers to increase their encounter opportunity, and in turn achieves efficient media content delivery among them. Then a router-centric prediction method is designed to collect passengers’ historical path information to determine the best delivery scheme. We evaluate the feasibility and the performance of the proposed infrastructure as well as the delivery scheme, using real data set from an urban transport system. The simulation results demonstrate the proposed system is highly practical in terms of the memory usage of routers and the maximum achievable data transfer rate.     

车联网场景下基于内容中心网络的优化缓存策略

车联网中,如何有效选择缓存位置和缓存内容对于提高整体网络性能至关重要。针对上述问题,引入了内容中心网络技术,提出了一种新的优化缓存策略——缓存位置和缓存内容的选择取决于车辆节点值和内容流行度(Vehicle Node Value and Content Popularity,VNVCP)。首先,定义了连通性、中间中心性和特征向量中心性3个车辆节点属性用来评估车辆节点的值,具有不同值的车辆节点缓存具有不同流行度的内容,内容的重要性由其受欢迎程度决定。其次,该策略利用不同类型内容受欢迎程度的差异确保缓存内容分布均匀,同时评估来自多个属性的车辆节点的值以提高车辆节点利用率。仿真结果表明,VNVCP在缓存命中率、平均跳数和传输延迟方面明显优于传统的LCE(Leave Copy Every where)、Prob(0.5)和MPC(Most Popular Content)。     

CCN中基于替换率的缓存空间动态借调机制

针对内容中心网络(CCN, content centric networking)节点存储资源的有效利用和优化配给问题,在同质化缓存分配的基础上,提出了一种基于替换率的缓存空间动态借调机制。该机制从节点存储空间使用状态的动态差异性出发,首先对于缓存资源借调的合理性给予证明,进而,依据节点对于存储资源的需求程度,动态地执行缓存借调,将相对空闲的存储资源分配给需求程度更大的节点支配,换取过载节点缓存性能的提升。该机制减小了内容请求跳数,提高了缓存命中率,以少量额外的代价换取了内容请求开销的显著下降,提升了存储资源整体利用率,仿真结果验证了其有效性。     

Time-sensitive software-defined networking (Ts-SDN) control architecture for flexi-grid optical networks with data center application

Data center interconnected by flexi-grid optical networks is a promising scenario to meet the high burstiness and high bandwidth requirement of data center application, because flexi-grid optical networks can allocate spectral resources for applications in a dynamic, tunable and efficient control manner. Meanwhile, as centralized control architecture, the software-defined networking (SDN) enabled by OpenFlow protocol can provide maximum flexibility for the networks and make a unified control over various resources for the joint optimization of data center and network resources. Time factor is firstly introduced into SDN-based control architecture for flexi-grid optical networks supporting data center application. A traffic model considering time factor is proposed, and a requirement parameter, i.e., bandwidth-period product is adopted for the service requirement measurement. Then, time-sensitive software-defined networking (Ts-SDN)-based control architecture is designed with OpenFlow protocol extension. A novel deadline-driven PCE algorithm is proposed for the deadline-driven service under Ts-SDN-based control architecture, which can complete data center selection, path computation and bandwidth resource allocation. Finally, simulation results shows that our proposed Ts-SDN control architecture and deadline-driven PCE algorithm can improve the application and network performance to a large extent in blocking probability.     

Progress in vacuum photothermal processing (VPP)

Vacuum photothermal processing (VPP) is the follower of rapid thermal processing (RTP) in thin film technologies. It is clear now that simultaneous action of high energetic photons (more than 1.5 eV) and electron beam, significantly affect surfaces of thin film systems. Furthermore, the interfaces between metal contacts and semiconductors (Si, Ge) undergone this simultaneous influence, tend to vary their electronic properties. The novel VPP method decreases surface and interface roughness in metal-semiconductor contacts. The electrons flow while VPP may be controlled using a special tungsten grid attached to a DC voltage. This control in the electrons flow enables a smooth variation of the potential barrier amplitude within the metal-semiconductor contacts.VPP experiments were done for following metal-semiconductors systems: Au, Ag, Al, Ti, Ni, In, Cu, V in contact with Si. The obtained results clearly indicate on a broad application range of the VPP process in semiconductors and in the thin film industry.