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Privacy preservation in secure group communications for?vehicular ad hoc networks

Secure communications for vehicular ad hoc networks (VANETs) have become an important research issue these years. Many protocols for secure vehicle-to-vehicle communications and vehicle-to-infrastructure communications have been proposed, yet fewer protocols are concerned with secure group communications for VANETs. Of those existing protocols for group communications, some of them form a group of vehicles based on geographical regions and provide broadcasting to the group members with or without message confidentiality. The others allow secure vehicle-to-vehicle communications within a group with session keys, but they do not preserve user privacy for communicating parties within the group. In this paper, we propose a novel group communication scheme for vehicular networks, in which a group is formed by a set of related vehicles of the same purpose, such as a platoon of recreational vehicles targeted for the same tourist spot. The scheme not only offers efficient and secure group communications but also provides privacy preservation for vehicle-to-vehicle communications within a group. Security analysis is given to demonstrate the robustness of the proposed scheme.     

Can energy optimization lead to economic and environmental waste in LPWAN architectures?

As low-power wide-area network (LPWAN) end devices (EDs) are deployed in massive scale, their economic and environmental costs of operation are becoming too significant to ignore and too difficult to estimate. While LPWAN architectures and protocols are designed to primarily save energy, this study shows that energy saving does not necessarily lead to lower cost or environmental footprint of the network. Accordingly, a theoretical framework is proposed to estimate the operational expenditure (OpEx) and environmental footprint of LPWAN EDs. An extended constrained optimization model is provided for the ED link assignment to gateways (GWs) based on heterogeneous ED configurations and hardware specifications. Based on the models, a simulation framework is developed which demonstrates that OpEx, energy consumption, and environmental footprint can be in conflict with each other as constrained optimization objectives. We demonstrate different ways to achieve compromises in each dimension for overall improved network performance.     

Consumers’ acceptance of information and communications technology in tourism: A review

The impact of information and communications technology (ICT) in tourism (e-tourism) has altered the ways tourism services are accessed and consumed. Ubiquitous and highly innovative ICTs provide different channels for consumers to use tourism services; thus, studies on e-tourism are numerous and fragmented. Different factors account for how consumers embrace these channels. The purpose of this study is to review studies on consumers’ acceptance or adoption of e-tourism in order to group the studies, synthesize the theories, models and frameworks used and identify the antecedents influencing consumers’ e-tourism acceptance and usage. A total of 71 studies from 2005 to 2016 (inclusive) from both tourism-based and non-tourism-based journals were selected, synthesized, and included. Based on their contexts, similarity and relevance, the 71 studies were segregated into three distinct groups. This study found that research among the groups is uneven. Implications and research directions are suggested.     

Zhao JiBin emphasizes China Tietong should enlarge private network coverage and make great progress in network regionalization

President Zhao Jibin of China Titong goes to Jiangsu to do some surveys and after listening to the working report of Jiangsu Tietong, he inspects the network development in Nanjing, Suzhou, Changzhou and other cities. Zhao JiBin emphasizes China Tietong should be on the way of ＂enlarge private network coverage and make great progress in network regionalization＂, make every effort to lay a solid management foundation and improve management level so as to ensure the accurate orientation and implement of the whole development strategy. All members of China Tietong must hold a clear understanding about future development direction.     

Cooperation-based resource allocation and call admission for?wireless network operators

The increasing number of radio access technologies and the availability of multi-radio devices boost the need for novel resource allocation schemes in cellular networks. This paper uses a cooperative game theoretic approach for resource allocation at the network level, while utilizing simultaneous use of available radio interfaces at the device level. We model resource allocation management using the well known bankruptcy model and apply Kalai-Smorodinsky bargaining solution method to find a distribution rule, based on which we propose resource allocation and call admission control schemes. Performance analysis of our allocation and control schemes demonstrates significant improvements over previous approaches in terms of utilization of the available bandwidth and the number of call drops. We also study the performance of proposed approach for different operator policies.     

Method of correlation function for analyzing cross-sensitivity of strain and temperature in fiber grating sensors

A novel method of correlation function for analyzing cross-sensitivity between strain and temperature is reported for the first time in this paper. Using the new method,the correlative characteristics between strain and temperature of fiber Bragg grating sensors are studied both theoretically and experimentally The experimental results accord with the theoretical calculations.     

Large-scale IP network behavior anomaly detection and?identification using substructure-based approach and?multivariate time series mining

In this paper, a substructure-based network behavior anomaly detection approach, called WFS (Weighted Frequent Subgraphs), is proposed to detect the anomalies of a large-scale IP networks. With application of WFS, an entire graph is examined, unusual substructures of which are reported. Due to additional information given by the graph, the anomalies are able to be detected more accurately. With multivariate time series motif association rules mining (MTSMARM), the patterns of abnormal traffic behavior are able to be obtained. In order to verify the above proposals, experiments are conducted and, together with application of backbone networks (Internet2) Netflow data, show some positive results.     

OBS路由器中交流耦合突发模式光接收机的设计方法

基于拓展带宽的设计方法,提出一种适于OBS的交流耦合突发模式光接收机设计方法.分析与仿真证明该方法有效地降低由交流耦合电容引入的功率代价,并降低系统对信号频谱中低频成分的限制.在1.25Gb/s的信道速率下,本设计在300ns内实现信道同步,并达到很好的灵敏度指标,打破了交流耦合突发接收机在高速应用中的局限.     

基于改进型头部丢弃的光突发竞争解决方案

为了避免"部分丢弃"策略两个固有缺陷(即"虚假竞争"和"过量丢弃")的影响,并最大限度地为上层应用提供有区分的承载服务,在加权型突发装配机制、QoS化偏移时间设置的基础上,提出了一种改进型头部丢弃方案.它能按照突发优先级的高低和截断突发相对长度的大小有选择性地丢弃突发头部或整个突发.与其他策略相比,该方案在合适的头部丢弃门限下,其优势较突出:一方面总分组丢失概率有所改善;另一方面具有一定的QoS保障能力,能为不同类别的分组提供有区分的传输服务.     

Optimized TQ-MAP: An Adaptive Mapping Mechanism to Guarantee the Coherence of QoS Support from IP to OBS

Because of its scalability, the idea of coarse packet classification can be utilized to OBS networks. However, due to the limited number of priorities supported by OBS networks, we usually adopt a many-to-one composite class burst (CCB) assembly technique, e.g., N:1-CCB. In this kind of technique, there are two aspects related to scalable QoS support, i.e., mapping relationship and assembly resource allocation. This paper simultaneously takes the two aspects into consideration, and proposes a novel assembly mapping mechanism, called Optimized TQ-MAP, in which the most important feature is adaptivity. Based on nonlinear programming and differential calculus, it allocates the burst assembling capacity between classes fairly, efficiently and differentially, and matches IP QoS requirement with OBS QoS capacity as possible as it can. The simulation results show that Optimized TQ-MAP is more adaptive, and can efficiently guarantee the coherence of QoS support from IP to OBS.     

BS路由协议的FPGA实现方案

研究了光突发交换(OBS)网络路由协议。以FPGA芯片EP2C20Q240C8为基础,通过模拟OBS节点之间的通信,对协议的4类帧的通信流程进行了验证。最后,对该路由协议的时序仿真结果、资源占用情况和时延进行了分析,结果表明,该OBS路由协议实现方案能够满足OBS网络的通信要求。     

一种非循环的光突发交换网络偏射路由算法

文章提出了一种非循环的应用于光突发交换(OBS)网络的偏射路由算法．它基于各网络节点的路径度和平均跳转数来确定偏射路径．通过建立OBS网络仿真模型。从数据突发的丢失率、平均跳转次数和端到端延时等方面来对其进行评价．仿真结果表明，该算法能确定有效的非循环偏射路径，为OBS网络提供了公平的网络资源利用．     

PON与OBS网络互连结构的研究

光突发交换(OBS)网络的城域网应用需要解决与接入网的互连问题。针对基于集成节点的PON与OBS网络互连方案,研究了集成节点的功能与组成结构,分析了模块之间的信息交互,给出了集成节点结构的一种设计方案,并简单讨论了基于这一方案的汇聚机制和动态带宽分配算法。     

OBS中基于分割和波长转换的冲突解决机制

提出了一种"先分割后波长转换"的冲突解决机制。当冲突发生时,首先对低优先级突发包进行分割;不冲突部分直接在事先预留的输出数据信道上处理,冲突部分通过WC转换到空闲的波长信道上。仿真结果表明,高优先级突发包的丢失率比低优先级的要低,并且各优先级突发包的丢失率随核心节点WC转换度的增加而降低。     

光突发交换网络中支持业务区分的多路由机制研究

针对光突发交换(OBS)网络的多路由机制多是考虑一种业务而对多业务区分的多路由机制研究偏少这种现状,提出了一种支持业务区分的多路由(MRSD)机制。在发送各个服务等级的业务之前,首先在没有共享风险链路的多条路由上发送请求包获得各条路由上的多种优先级业务的负载情况,然后根据爱尔兰固定点近似分析法计算各种优先级业务在不同路由上的丢包率,并为每种优先级业务选择一条使本业务丢包率最小的路由;在一个核心节点内,则采用基于额外偏置时间的业务区分方法实现不同优先级业务的区分,将各种业务根据链路状态信息分配到没有共享风险链路的多条路由上去传输,从而在减少突发丢失率(BLP)的同时实现了多种优先级业务在路由上的区分。仿真结果表明,这种多路由机制能够有效降低网络的BLP,实现区分服务。     

A burst loss probability model with impatient customer feature for optical burst switching networks

We consider optical delay line buffer as a solution to reduce the number of lost burst in optical burst switching, one of the promising candidates for future networks. Such network takes burst loss as an important performance criteria in the design step. Network performance, however, cannot be captured efficiently using traditional queueing models, because they often ignore the impatience of messages traveling through optical switches which is one of the popular issues in communication networks. In this paper, we develop an analytic model for this system using queueing theory and considering special impatience features. Simulation results show that (i) the developed model with impatience features can decrease burst loss probability ( ? 10%) compared with other approaches, and (ii) applying that model, we demonstrate that shared buffer architecture in optical burst switching network with optical buffer often achieves lower burst loss probability than dedicated buffer way in several different scenarios. Copyright © 2014 John Wiley & Sons, Ltd.     

一种基于突发长度预测的光突发汇聚机制

提出了一种基于突发长度预测的固定时间汇聚方法.边缘节点在监测时间段内对到达的数据流进行监测,并且根据监测的结果预测在固定的汇聚时间内完成汇聚的突发包长度,提前将控制分组转发到核心网络中进行资源预留.通过理论分析及计算机仿真表明,这种汇聚方法能够有效地降低光突发交换网络中的端到端延迟.