对等网的快速路由模型

在DHT基础上建立一种快速的自组织路由模型(FSRM),设计了该模型的路由查找方法,节点加入与离开机制。同时,针对扰动环境下临近节点选择问题,提出稳定性阈值度量的方法,保证了对等网的快速路由和快速收敛。并在仿真测试中对该模型的性能进行了分析,证明该模型在收敛时间,节点查询速度,和对扰动的适应性方面优于传统的模型。     

复杂网络理论在对等网络特性分析中的应用

基于现有的复杂网络理论,研究了对等网络的复杂特性,并就对等网络中节点度和节点间平均最短路径两个特征参数进行算法设计和仿真.仿真结果表明,对等网络中使用复杂网络理论的特性分析理论结果与实验结果基本一致,能准确反映对等网络的特性.     

基于对等网络的医学影像服务系统通讯平台设计与应用

通过建立医学影像对等网络通讯平台,以便于研究对等网络在各医学影像服务中的应用,描述了其组织结构设计与节点管理,阐述了对等节点间在不同区域建立通讯连接的方法,通过远程在线会诊为实例,把医学影像对等网络通讯平台的使用方法进行了详细的介绍。     

针对NFC点对点模式的传输认证改进方案

为完善目前NFC点对点模式的漏洞,设计出一套全新的传输认证协议。采用着色Petri网进行理论建模,查找并论证安全风险的存在。通过融合多种已有的优秀算法,结合设备实际,给出全新的加密及认证方法,生成基于近场通信协议栈的安全隧道,并从算法复杂度的角度分析改进后协议的安全性。新协议能够抵御针对近场通信的多种攻击方式,稳健运行的同时更有着良好的应用前景,在安全上予以更高层次的保证,真正实现"碰一碰"即可完成交互的目标。     

Super peer selection strategy in peer‐to‐peer networks based on learning automata

A super peer is a peer that has the highest capacity in comparison with other peers in the network. It is trying to reduce the load of the rest of the peers and improve network performance. Selecting a super peer in a peer‐to‐peer–based network is a very crucial challenge. As the ability of peers are very different, by considering capacity of each peer and selecting a proper role, we can use network components much more efficiently. Because of the dynamicity of these networks, comparative methods of selecting super peers is of special importance. Comparative selection is continuously trying to select proper super peer. In recent studies, learning automata was introduced as a powerful learning model to solve this issue. In most of the studies, learning automata with an S model is employed. In this article, another selection method of learning automata with a P model environment is presented and its capability for super peer selection is shown. Moreover, simulation results show that removing some of the super peers would result in better performance in terms of inversion time in the high level of super‐peer capacity, required time for selecting proper super peer, and super peer tolerance.     

Opto firms peer past telecom bust

The paper discusses the the effect of the collapse of the telecommunication market on the UK optoelectronics industry. A number of optoelectronics businesses have gone to the wall in the UK but there is still overcapacity. Consolidation or diversification are two of the options for UK optoelectronics companies as they face the future.     

对等网络运营模式探讨

完整意义上的信息交流应该包括两个范畴：点和多点之间的信息交流、点对点之间的信息交流。C/S和B/S为前者提供了很好的手段，而在对等网络（P2P）兴起之前，人们似乎一直没有在网络上找到实时在线进行点对点交流的好办法。C/S和B/S技术直接导致了互联网的第一次高速发展，而解决了后一个问题的P2P是不是将带来互联网的又一次革命？P2P的概念及其发展P2P（peer-to-peer）可以称为对等网络，就是利用客户端的处理能力，实现客户端之间的点到点通信，实现通信与服务端的无关性（或者说客户终端就是服务端）。它使得网络上的每个用户直…     

网络同侪互评系统的设计与实现

从对网络协作学习理论和教学实践中分析,尝试通过凯利方格技术与模糊综合评价的整合提出一种符合当前网络协作学习的同侪互评模式,深入探索与分析学生作品信息,使学生学习作品的教育价值在协作学习中得以最大程度开发、利用。     

数据中心间空闲带宽感知的内容分发算法

针对数据中心链路上存在时间窗不重叠的空闲带宽的情况,提出了利用该带宽分发容迟数据的基本思路,进而设计了一种分布式可扩展的空闲带宽感知的节点选择算法LBAPS,该算法避免了集中优化,适合目标节点较多的情况。为了匹配最优的带宽空闲节点,LBAPS按综合度量进行节点选择;为了优先把文件块上传到空闲带宽大的节点以及尽早把不同的块分布到更多节点,LBAPS按阈值预留资源以及按时间片退出上传。基于LBAPS实现了内容云原型系统P2PStitcher。PlanetLab上的实验表明,LBAPS算法所提出的策略可以有效地减少平均分发时间。     

Visualization of Ethereum P2P network topology and peer properties

Ethereum is arguably the second most popular cryptocurrency-based network after Bitcoin. Both use the distributed ledger technology known as the blockchain, which is considered secure. However, the provided security level is proportional to the number of connected nodes, the number of influential nodes, and the supported amount of hash power. Thus, the knowledge of the network properties and nodes' behavior is helpful to protect the network from possible attacks such as double-spending attacks, DDoS attacks, 51% attacks, and Sybil attacks. This paper proposes a node discovery mechanism, which performs a P2P link discovery on the Ethereum main network. For that, we develop Search-node, a modified version of Ethereum client that searches for all participating nodes in the blockchain network, stores the node information in the Bucket, and then processes the peer discovery method. Based on the collected data, we first visualize the Ethereum network topology and analyze the attributes of the network such as node degree, path length, diameter, and clustering coefficient. We then analyze the node properties and provide analytical results regarding the relationship between nodes, heavily connected nodes, node geo-distribution, security issues, and possible attacks over the influential nodes. As a result, we have identified 68,406 nodes with a total of 642,034 edges. By analyzing the collected data, we have found that the diameter in the Ethereum network is equal to 8. The node degree is over 19, which is two times higher than the default configuration.     

Bitcoin's dynamic peer‐to‐peer topology

Topology discovery is a prerequisite when investigating the network properties; with the enormous number of Bitcoin users and performance issues, it becomes critical to analyse the network in a fashion that makes it possible to detect all Bitcoin's nodes and understand their behaviour. In massive, dynamic, and distributed peer‐to‐peer (P2P) networks like Bitcoin, where thousands of updates occur per second, it is hard to obtain an accurate topology representing the structure of the network as a graph with nodes and links by using the traditional local measurement approaches based on batches, offline data, or on the discovery of the topology around a small set of nodes and then combine them to discover an approximate network topology. All of which present some limitation when applying them on blockchain‐based networks. In this paper, we propose a topology discovery system that performs a real‐time data collection and analysis for Bitcoin P2P links, which assembles incoming nodes information for deeper graph analysis processing. The topology discovery system allows us to gain knowledge on the Bitcoin network size, the network stability in terms of reachable, churn, and well‐connected nodes, as well as some data regarding the effects of some countries' Internet infrastructure on Bitcoin traffic.     

Analysis of user-driven peer selection in peer-to-peer backup and?storage systems

In this paper we present a model of peer-to-peer backup and storage systems in which users have the ability to selfishly select remote peers they want to exchange data with. In our work, peer characteristics (e.g., on-line availability, dedicated bandwidth) play an important role and are reflected in the model through a single parameter, termed profile. We show that selecting remote peers selfishly, based on their profiles, creates incentives for users to improve their contribution to the system. Our work is based on an extension to well known results in Matching Theory, which allows us to formulate the Stable Exchange Game, in which we shift the algorithmic nature of matching problems to a game theoretic framework. We propose a polynomial-time algorithm to compute welfare-maximizing stable exchanges between peers and show, using an evolutionary game theoretic framework, that even semi-random peer selection strategies, that are easily implementable in practice, can be effective in providing incentives to users in order to improve their profiles.     

P2P文件共享系统中对等点发现机制的实现

由于P2P网络的动态性，如何有效和准确地进行对等点定位成为P2P网络中的关键技术。本文在分析现在P2P网络中几种常见的对等点发现机制的优点与不足的基础上，提出了利用IP多播技术和JXTA平台实现的对等点发现机制，并讨论了其在P2P文件共享系统中的实现方法。     

Distributed collaborative key agreement and authentication protocols for dynamic peer Groups

We consider several distributed collaborative key agreement and authentication protocols for dynamic peer groups. There are several important characteristics which make this problem different from traditional secure group communication. They are: 1) distributed nature in which there is no centralized key server; 2) collaborative nature in which the group key is contributory (i.e., each group member will collaboratively contribute its part to the global group key); and 3) dynamic nature in which existing members may leave the group while new members may join. Instead of performing individual rekeying operations, i.e., recomputing the group key after every join or leave request, we discuss an interval-based approach of rekeying. We consider three interval-based distributed rekeying algorithms, or interval-based algorithms for short, for updating the group key: 1) the Rebuild algorithm; 2) the Batch algorithm; and 3) the Queue-batch algorithm. Performance of these three interval-based algorithms under different settings, such as different join and leave probabilities,is analyzed. We show that the interval-based algorithms significantly outperform the individual rekeying approach and that the Queue-batch algorithm performs the best among the three interval-based algorithms. More importantly, the Queue-batch algorithm can substantially reduce the computation and communication workload in a highly dynamic environment. We further enhance the interval-based algorithms in two aspects: authentication and implementation. Authentication focuses on the security improvement, while implementation realizes the interval-based algorithms in real network settings. Our work provides a fundamental understanding about establishing a group key via a distributed and collaborative approach for a dynamic peer group.     

A self‐adaptive algorithm for super‐peer selection considering the mobility of peers in cognitive mobile peer‐to‐peer networks

Cognitive peer‐to‐peer networks are obtained from a combination of cognitive networking concepts and peer‐to‐peer networks. These networks are able to improve their performance while operating under dynamic and unknown environments. A cognitive peer‐to‐peer network tries to learn an appropriate configuration for itself considering the unknown physical properties of peers. Cognitive mobile peer‐to‐peer networks refer to cognitive peer‐to‐peer networks which are built over mobile ad hoc networks. In these networks, heterogeneity of the mobility of peers and resource limitation in wireless networks create challenges for network management algorithms. Because of the dynamicity of these networks, the management algorithms should be designated in self‐adaptive manner. In one type of these networks, some peers, called super‐peers, undertake to perform network managerial tasks. The mobility of peers leads to connection failure among peers and reselection of new super‐peers. Therefore, the selection of super‐peers, due to their influential role, requires an algorithm that considers the peers' mobility. Up to now, no self‐adaptive algorithm has been designated for super‐peer selection considering the mobility of peers in a self‐adaptive manner. This paper proposes M‐SSBLA, a self‐adaptive algorithm for super‐peer selection considering the mobility of peers based on learning automata. The proposed algorithm is obtained from cooperation between a learning automata‐based cognitive engine and MIS. MIS is a well‐known super‐peer selection algorithm in mobile peer‐to‐peer networks. We compared the proposed algorithm with recently reported algorithms, especially for a network with high mobility. Simulation results show that the proposed algorithm can cover maximum ordinary‐peer with a few super‐peer and improve robustness against super‐peer failures while decreasing maintenance overhead.     

Peer‐to‐peer cooperation for GPS positioning

This paper presents a peer‐to‐peer cooperative positioning technique together with its performance assessment. The cooperation between the two GPS receivers is realized by means of a wireless LAN connection and is significantly influenced by the accurateness of the synchronization between the two terminals. Both the outdoor‐to‐indoor and outdoor‐to‐outdoor scenarios are considered. For each scenario, we assess the satellite signal acquisition and its computational load and the performance in terms of position accuracy and time‐to‐first‐fix of the positioning procedure. Copyright © 2016 John Wiley & Sons, Ltd.     

Fast detection and removal of impulsive noise using peer groups and fuzzy metrics

A novel approach to impulsive noise detection in color images is introduced. In the paper, the peer group concept is redefined by means of a certain fuzzy metric. This concept is employed for the fast detection of noisy pixels by taking advantage of the fuzzy metric properties. On the basis of the noisy pixel detection a switching filter between the arithmetic mean filter (AMF) and the identity operation is proposed. The proposed switching filter achieves a trade-off between noise suppression and signal-detail preservation and is faster than recently introduced switching filters based on the peer group concept.     

基于GMPLS对等模型的智能光网络QoS模型设计

介绍了智能光网络层叠模型和对等模型的特点,简要分析了智能光网络的QoS机制,提出了一种基于GMPLS对等模型的智能光网络QoS模型,通过对此模型下的数据业务的时延、链路的利用率进行仿真,验证了所设计的QoS模型的优越性和可行性.