基于跨层的认知无线电绿色网络关键技术综述

探讨了跨层的认知无线电技术在绿色网络中的应用,绿色网络以节能为目标,收集和讨论了将认知无线电的各种跨层技术应用于绿色网络的关键技术。首先,讨论了认知无线电绿色网络跨层的方法,从频谱架构、跨层结构两方面分别展开;其次,对多种认知无线电跨层方案,以节能为目标做出对比;最后,为绿色网络的认知无线电跨层技术相关开放性问题提出一定见解,以期为今后设计绿色网络跨层架构提供指导方案。     

应用OTV技术实现云计算跨二层网络融合方案浅析

由于单个数据中心节点难以提供足够的服务器资源满足特定用户的需求,为满足用户跨域融合的业务需求,首先简要介绍了OTV技术,接着对不同机房应用OTV技术实现跨二层网络融合的方案进行分析,并比较了OTV技术和传统的二层网络互联技术,最后对OTV技术在云计算网络中应用优势进行总结。     

超宽带安全监控网络跨层优化模型的设计研究

本文研究了超宽带安全监控网络跨层优化模型的设计,首先,介绍了超宽带技术的优势和应用场景,然后分析了当前超宽带安全监控网络面临的挑战。以UWB传感器网络为基础提出了网络模型,提出了一个跨层优化的模型,该模型结合了物理层、调度层和网络层的优化方法,以提升超宽带安全监控网络的性能,围绕子频带信道容量、目标函数及数据传输模型构建了跨层模型。结果证实,该模型的应用可保障安全网络的稳定性,有利于提高数据传输速率,同时保证了数据传输的安全性。     

云数据中心网络虚拟化技术实现及应用

传统数据中心的三层体系结构无法满足大数据和云计算的要求,大二层技术开始逐渐流行,在数据中心硬件设备虚拟化后,数据中心内部及跨数据中心的数据通信要求网络必然实现虚拟化。首先阐述网络虚拟化的要求,然后探讨在数据中心内网络虚拟化及跨数据中心网络部署方式,最后通过实际应用阐述数据中心的网络部署并就部署中出现的问题进行总结。     

IP+光骨干网中SDN技术的应用研究

在由IP层设备和光层的波分设备组成的骨干网场景下,应用SDN技术将会有效的整合骨干网络中IP/MPLS网络和光网络的资源,提升资源利用率,提高网络运维效率,降低总拥有成本,部署时需重点考虑跨层协同和多厂家协同。     

基于MIMO-OFDM的5G通信跨层安全传输技术研究

在对5G通信跨层安全传输技术进行研究的过程中,将MIMO-OFDM应用于5G通信跨层安全传输技术中,提出一种基于MIMO-OFDM的5G通信跨层安全传输技术。首先对5G通信系统的认证模型进行构建,以通过物理层对5G通信网络进行安全认证。基于MIMO-OFDM系统制订5G通信跨层安全传输方案,方案包括两个方向,一个方向是加密发射端,另一个方向是解密接收端,以实现5G通信跨层安全传输。通过对比实验验证该技术的接收者误码率低于现有技术,实现了性能提升。     

ad hoc网络中跨层设计方法的研究

ad hoc网络与传统有线和无线蜂窝网络有着显著的区别,基于传统的分层协议栈的设计方法不再适合ad hoc网络,而应采用一种新型的跨层协议栈和跨层设计方法.本文首先阐述了ad hoc网络的特点和传统的分层协议栈的弊端,介绍了跨层设计的概念.然后,详细分析了ad hoc网络中跨层设计的方法,包括策略、体系结构和信令交互方式,探讨了跨层设计的相关技术和面临的挑战.最后,总结了全文并指出了今后的工作方向.     

无线传感器网络跨层优化研究

无线传感器网络系统的跨层优化理论在当前是一个研究热点.在传统的无线网络设计中,一般是沿用有线网络的设计思想,特别是利用因特网的设计思想来设计无线网络.然而由于无线传感器具有网络资源和能量受限的特点,这就使得传统的有线网络中分层设计的思想遇到了未曾预计的尴尬与挑战.本文对无线传感器网络中的跨层优化工作原理进行了叙述,比较了各个跨层优化技术的特点.最后阐述了当前跨层设计技术面临的挑战.     

IPover ATM宽带技术在金融业中的应用前景

目前金融业传统的网络架构为IP网络,传统的IP技术存在路由器瓶颈、无连接、分组长度可变且分组独立传输、时延不确定性、QOS服务质量难以保证等问题,因而无法确保实时性要求较高的数据流可靠稳定地传输。为了将传统的IP骨干网改造为宽带骨干网,可采用多种宽带骨干网技术,如IPover ATM、IPover SDH、IPover DWDM/Opical等技术。本文介绍了一种将二层ATM、三层IP路由器、QOS服务质量技术结合起来的IPover ATM网络控制与安全解决方案及其在金融业中的应用前景。     

认知无线Mesh网络跨层设计研究

传统网络的分层设计不能满足具有特殊QoS需求的无线宽带业务,无法应对动态频谱接入的无线通信环境。采用联合开放、架构灵活的跨层设计研究无线Mesh网络接入技术日渐成为热点。本文首先介绍了跨层设计的起源、分类,然后分析了认知无线Mesh网络跨层研究的挑战、难点及最新进展,并提出利用跨层设计实现路由及频谱管理的一种构想,最后展望了认知无线Mesh网络跨层研究的新方向。     

The Energy-Aware Operational Time of Wireless Ad-Hoc Sensor Networks

Sensor networks are deployed in numerous military and civil applications, such as remote target detection, weather monitoring, weather forecast, natural resource exploration and disaster management. Despite having many potential applications, wireless sensor networks still face a number of challenges due to their particular characteristics that other wireless networks, like cellular networks or mobile ad hoc networks do not have. The most difficult challenge of the design of wireless sensor networks is the limited energy resource of the battery of the sensors. This limited resource restricts the operational time that wireless sensor networks can function in their applications. Routing protocols play a major part in the energy efficiency of wireless sensor networks because data communication dissipates most of the energy resource of the networks. This paper studies the importance of considering neighboring nodes in the energy efficiency routing problem. After showing that the routing problem that considers the remaining energy of all sensor nodes is NP-complete, heuristics are proposed for the problem. Simulation results show that the routing algorithm that considers the remaining energy of all sensor nodes improves the system lifetime significantly compared to that of minimum transmission energy algorithms. Also, the energy dissipation of neighboring nodes accounts for a considerable amount of the total energy dissipation. Therefore, a method that reduces the energy dissipation by notifying the neighboring nodes to turn off their radio when not necessary is proposed. By reducing the unnecessary energy dissipation of the neighbors, the lifetime is increased significantly.     

Joint resource reconfiguration and robust routing for cognitive radio networks: a robust optimization approach

Cognitive radio (CR) networks comprise a number of spectrum agile nodes with the capability of spectrum detection. Applying techniques of spectrum sharing in CR networks can achieve the efficient utilization of network resources. Usually, data rates of user sessions are time varied because of the dynamic behaviors of CR networks. It is expected that the occurrence of link outage should be avoided and incorporated into the routing design under conditions of increasingly crowded spectrum. This paper proposes an integral framework, which considers these two correlated schemes (resource reconfiguration and robust routing) simultaneously. For that, the resource reconfiguration scheme is developed for the efficient usage of network resources and aims at reducing the occupancy of licensed bands. The link outage, resulting from random session rate, is confined within an acceptable range by using strategy of virtual ‘network portfolio’. A robust optimization approach is proposed to guarantee reliable data transmission among possible interfering links. Both these two items (resource reconfiguration and robust routing) are formulated in a framework of cross‐layer optimization. The evolutionary process of CR network states is provided in simulations, where the results show that the joint design proposal can achieve the least interferences among different licensed users while realizing robust routing. Copyright © 2013 John Wiley & Sons, Ltd.     

Service capacity in vehicular networks: A resource dissemination analysis

The support of peer-to-peer (P2P) resource sharing in dynamic scenarios is one of the most challenging research fields for both its expected commercial and technological impact on everyday life. To this purpose, resource sharing within a vehicular network can facilitate an acceleration in the dissemination process and increase the number of nodes in the network which possess a certain resource and can share it with other devices. This performance parameter, denoted as service capacity, has been recently studied in the context of wired P2P networks but its calculation in mobile networks is still an open problem. In this paper, we perform a service capacity analysis in P2P vehicular networks where nodes move according to traffic patterns which consider realistic car interactions such as acceleration, breaking and inter-car minimum safety distance maintenance and, while moving, perform resource dissemination. More specifically, we will present a service capacity analysis which considers the impact of traffic correlation and node density on the number of mobile vehicles in the network possessing a certain resource. Finally, we will also estimate the impact of link errors on the probability that a resource is propagated up to a certain location, in a given time.     

A fairness adaptive TDMA scheduling algorithm for wireless sensor networks with unreliable links

Wireless sensor networks consist of a large number of wireless sensor nodes that organize themselves into multihop radio networks. With different link quality, different distance to the sink, nodes in a network are not treated equally, especially in a network with high traffic. In this paper, we propose a fairness adaptive time division multiple access scheduling algorithm (FATS) considering the fairness of network resource allocation. This algorithm, combining several heuristic algorithms, can assign network resources to the nodes to lead to maximizing the minimum end‐to‐end packet delivery success ratio. Because the wireless link is usually time‐varying, this algorithm can also assign the time slots to the nodes adaptively and energy‐efficiently according to the variation of link quality. We define several criteria for the slot assignment and adjustment. The change in slot assignment can be finished quickly during normal packet transmission, which causes little affect to the network. Meanwhile, considering the required data rate, FATS can achieve the maximum transmission capacity of the network with specified static or dynamic reliability. The simulation results show that the FATS can significantly reduce the difference of the end‐to‐end packet delivery ratio, track the variation of link quality quickly, and achieve the fairness of resource allocation.Copyright © 2012 John Wiley & Sons, Ltd.     

Reference node placement and selection algorithm based on trilateration for indoor sensor networks

The key problem of location service in indoor sensor networks is to quickly and precisely acquire the position information of mobile nodes. Due to resource limitation of the sensor nodes, some of the traditional positioning algorithms, such as two‐phase positioning (TPP) algorithm, are too complicated to be implemented and they cannot provide the real‐time localization of the mobile node. We analyze the localization error, which is produced when one tries to estimate the mobile node using trilateration method in the localization process. We draw the conclusion that the localization error is the least when three reference nodes form an equilateral triangle. Therefore, we improve the TPP algorithm and propose reference node selection algorithm based on trilateration (RNST), which can provide real‐time localization service for the mobile nodes. Our proposed algorithm is verified by the simulation experiment. Based on the analysis of the acquired data and comparison with that of the TPP algorithm, we conclude that our algorithm can meet real‐time localization requirement of the mobile nodes in an indoor environment, and make the localization error less than that of the traditional algorithm; therefore our proposed algorithm can effectively solve the real‐time localization problem of the mobile nodes in indoor sensor networks. Copyright © 2008 John Wiley & Sons, Ltd.     

Coordinated multihop scheduling: a framework for end-to-end services

In multihop networks, packet schedulers at downstream nodes have an opportunity to make up for excessive latencies due to congestion at upstream nodes. Similarly, when packets incur low delays at upstream nodes, downstream nodes can reduce priority and schedule other packets first. The goal of this paper is to define a framework for design and analysis of coordinated multihop scheduling (CMS) which exploits such internode coordination. We first provide a general CMS definition which enables us to classify a number of schedulers from the literature, including G-EDF, FIFO+, CEDF, and work-conserving CJVC as examples of CMS schedulers. We then develop a distributed theory of traffic envelopes which enables us to derive end-to-end statistical admission control conditions for CMS schedulers. We show that CMS schedulers are able to limit traffic distortion to within a narrow range resulting in improved end-to-end performance and more efficient resource utilization. Consequently, our technique exploits statistical resource sharing among flows, classes, and nodes, and our results provide the first statistical multinode multiclass admission control algorithm for networks of work conserving servers.     

分布式协作通信网络中的MAC层协议

分布式协作网络通过节点间的相互合作来达到网络资源的共享,然而如何设计高效的媒体访问控制（MAC）层协议是分布式协作通信网络中的核心问题之一。文章基于MAC层协作的动机,探讨了分布式协作网络中MAC层协议设计所面临的问题和挑战,基于近年来涌现的典型协作MAC协议和协议性能的分析,得出结论：只有全面考虑分布式网络的特点和需求,合理地设计协议的各个环节,才能使协同通信技术在分布式网络中得到更好应用。     

基于射频能量收集的无线中继网络资源分配

针对现有射频能量收集网络资源分配研究局限于单个数据源场景,无法适配于多数据源网络的问题,提出了一种适用于多数据源场景的射频能量收集中继网络传输协议框架,在该框架内节点可作为源节点或中继节点传输自身数据或转发数据,并在其他节点的数据传输过程中完成射频能量收集。以协议框架为基础,分别以系统吞吐量及用户公平性为优化目标设计两种资源分配方案。仿真表明,两种方案可有效改善网络吞吐量及资源分配公平性。     

P2P资源均衡利用策略控制搭便车行为

P2P网络中大量存在的搭便车行为给网络的响应速度、可用性、健壮性等造成了很大影响。目前的研究重点是设计有效的P2P信任模型来抑制搭便车行为。文中借鉴社会经济发展策略,提出基于资源均衡利用的信誉评价方法,对资源贡献大、贡献与消费平衡的节点赋予高信誉度。使节点贡献其他节点需要的资源,消费资源时量入为出;同时为新节点提供基本信誉度来保障其尽早开展资源交易。仿真实验表明搭便车行为受到有效抑制,网络资源的利用率明显提高。     

基于IEEE 1500的NoC资源节点Wrapper设计

为确保不同资源节点在NoC系统中可靠地工作,亟需构建有高效、统一的资源节点测试方案。通过分析资源节点的测试特征和方法,选择IEEE 1500 Wrapper的可测性设计方案,在目前设计方法不足的基础上,提出针对不同端口工作时序复杂程度不同的特征设计不同的WBR单元以提高测试效率。实验以LIFO资源节点为例验证了Wrapper测试的有效性,结果表明改进设计方法可减少的WRCK时钟数等于LIFO资源节点矢量数的10倍,因此应用改进的设计方法可有效缩减测试时间。