针对命名数据网络(named data networking,NDN)中缓存冗余高、资源利用率低的问题,提出基于数据冗余包的协同缓存放置策略(cooperative cache placement strategy based on da-ta redundancy packet,CCPS-DRP)。该策略先对网络进行社区...针对命名数据网络(named data networking,NDN)中缓存冗余高、资源利用率低的问题,提出基于数据冗余包的协同缓存放置策略(cooperative cache placement strategy based on da-ta redundancy packet,CCPS-DRP)。该策略先对网络进行社区划分,再利用复杂网络中节点介数确定关键路由节点,将数据冗余包中的相同数据副本存放于其中,并动态管理冗余数据副本,实现关键节点集中管理与动态冗余清理的协同机制,以减少相同数据内容的重复缓存,使路由节点中的缓存容量得到充分利用,降低网络负载。实验结果表明,无论在均匀分布或高度偏斜分布的场景下,还是在严格资源限制或有较高资源的场景下,CCPS-DRP在缓存命中率和平均请求时延方面的性能均明显优于常见的随处缓存策略、概率缓存策略等,其通过协同缓存与冗余控制显著提升了网络性能。展开更多
This paper presents the hypermedia data model based on the infinity RS image information system we have developed.The hypermedia data model consists of different semantic units called nodes,and the associations betwee...This paper presents the hypermedia data model based on the infinity RS image information system we have developed.The hypermedia data model consists of different semantic units called nodes,and the associations between nodes are called links.This paper proposes three kinds of nodes (interior node,physical node and complex node) and two kinds of links (plane network structure link,hyper_cube network structure links).The hypermedia information system,based on the model and the basic data layer (the infiniy RS image),represents a digital globe.An approach to the “Getting Lost in the Hyper_space” problem is presented.The approach using the hypermedia data model is an efficient way of handling a large number of RS images in various geographical information systems.展开更多
Recently, the exponential rise in communication system demands has motivated global academia-industry to develop efficient communication technologies to fulfill energy efficiency and Quality of Service (QoS) demands. ...Recently, the exponential rise in communication system demands has motivated global academia-industry to develop efficient communication technologies to fulfill energy efficiency and Quality of Service (QoS) demands. Wireless Sensor Network (WSN) being one of the most efficient technologies possesses immense potential to serve major communication purposes including civil, defense and industrial purposes etc. The inclusion of sensor-mobility with WSN has broadened application horizon. The effectiveness of WSNs can be characterized by its ability to perform efficient data gathering and transmission to the base station for decision process. Clustering based routing scheme has been one of the dominating techniques for WSN systems;however key issues like, cluster formation, selection of the number of clusters and cluster heads, and data transmission decision from sensors to the mobile sink have always been an open research area. In this paper, a robust and energy efficient single mobile sink based WSN data gathering protocol is proposed. Unlike existing approaches, an enhanced centralized clustering model is developed on the basis of expectation-maximization (EEM) concept. Further, it is strengthened by using an optimal cluster count estimation technique that ensures that the number of clusters in the network region doesn’t introduce unwanted energy exhaustion. Meanwhile, the relative distance between sensor node and cluster head as well as mobile sink is used to make transmission (path) decision. Results exhibit that the proposed EEM based clustering with optimal cluster selection and optimal dynamic transmission decision enables higher throughput, fast data gathering, minima delay and energy consumption, and higher展开更多
文摘针对命名数据网络(named data networking,NDN)中缓存冗余高、资源利用率低的问题,提出基于数据冗余包的协同缓存放置策略(cooperative cache placement strategy based on da-ta redundancy packet,CCPS-DRP)。该策略先对网络进行社区划分,再利用复杂网络中节点介数确定关键路由节点,将数据冗余包中的相同数据副本存放于其中,并动态管理冗余数据副本,实现关键节点集中管理与动态冗余清理的协同机制,以减少相同数据内容的重复缓存,使路由节点中的缓存容量得到充分利用,降低网络负载。实验结果表明,无论在均匀分布或高度偏斜分布的场景下,还是在严格资源限制或有较高资源的场景下,CCPS-DRP在缓存命中率和平均请求时延方面的性能均明显优于常见的随处缓存策略、概率缓存策略等,其通过协同缓存与冗余控制显著提升了网络性能。
文摘This paper presents the hypermedia data model based on the infinity RS image information system we have developed.The hypermedia data model consists of different semantic units called nodes,and the associations between nodes are called links.This paper proposes three kinds of nodes (interior node,physical node and complex node) and two kinds of links (plane network structure link,hyper_cube network structure links).The hypermedia information system,based on the model and the basic data layer (the infiniy RS image),represents a digital globe.An approach to the “Getting Lost in the Hyper_space” problem is presented.The approach using the hypermedia data model is an efficient way of handling a large number of RS images in various geographical information systems.
文摘Recently, the exponential rise in communication system demands has motivated global academia-industry to develop efficient communication technologies to fulfill energy efficiency and Quality of Service (QoS) demands. Wireless Sensor Network (WSN) being one of the most efficient technologies possesses immense potential to serve major communication purposes including civil, defense and industrial purposes etc. The inclusion of sensor-mobility with WSN has broadened application horizon. The effectiveness of WSNs can be characterized by its ability to perform efficient data gathering and transmission to the base station for decision process. Clustering based routing scheme has been one of the dominating techniques for WSN systems;however key issues like, cluster formation, selection of the number of clusters and cluster heads, and data transmission decision from sensors to the mobile sink have always been an open research area. In this paper, a robust and energy efficient single mobile sink based WSN data gathering protocol is proposed. Unlike existing approaches, an enhanced centralized clustering model is developed on the basis of expectation-maximization (EEM) concept. Further, it is strengthened by using an optimal cluster count estimation technique that ensures that the number of clusters in the network region doesn’t introduce unwanted energy exhaustion. Meanwhile, the relative distance between sensor node and cluster head as well as mobile sink is used to make transmission (path) decision. Results exhibit that the proposed EEM based clustering with optimal cluster selection and optimal dynamic transmission decision enables higher throughput, fast data gathering, minima delay and energy consumption, and higher
