Minimum-Energy Broadcasting in Static Ad Hoc Wireless Networks

Energy conservation is a critical issue in ad hoc wireless networks for node and network life, as the nodes are powered by batteries only. One major approach for energy conservation is to route a communication session along the route which requires the lowest total energy consumption. This optimization problem is referred to as Minimum-Energy Routing. While the minimum-energy unicast routing problem can be solved in polynomial time by shortest-path algorithms, it remains open whether the minimum-energy broadcast routing problem can be solved in polynomial time, despite the NP-hardness of its general graph version. Recently three greedy heuristics were proposed in [11]: MST (minimum spanning tree), SPT (shortest-path tree), and BIP (broadcasting incremental power). They have been evaluated through simulations in [11], but little is known about their analytical performances. The main contribution of this paper is a quantitative characterization of their performances in terms of approximation ratios. By exploring geometric structures of Euclidean MSTs, we have been able to prove that the approximation ratio of MST is between 6 and 12, and the approximation ratio of BIP is between 13/3 and 12. On the other hand, we show that the approximation ratio of SPT is at least n/2, where n is the number of receiving nodes. To the best of our knowledge, these are the first analytical results for the minimum-energy broadcasting problem.     

无线传感器网络系统综述

介绍了无线传感器网络的概念、几种主要的无线传感器网络协议,尤其是MAC层协议的研究情况,给出了一些比较经典的无线传感器网络MAC协议的思想。     

无线传感器网络路由中的能量预测及算法实现

基于无线传感器网络中路由协议高效合理利用能量的要求,提出一种基于剩余能量预测的地理位置路由(EPGR,energy prediction and geographical routing)算法。算法通过建立传感器网络节点运作模型,及相邻节点剩余能量预测机制,优化路由选择。仿真和分析表明,EPGR算法能够有效地优化数据传输路径,均衡传感器网络节点的能量消耗,延长网络寿命。     

Channel Adaptive Shortest Path Routing for Ad Hoc Networks

1　IntroductionAdhocnetworksareformedwithoutrequiringthepreexistinginfrastructureorcentralizedadminis tration ,incontrasttocellularnetworks.Asidefromtheoriginalmilitaryapplication ,ithasapplicationinpublicsafetyandcommercialareas,butadaptiveprotocolsarerequiredinorderforthemtodoso .Twoimportantcharacteristicsofacommunicationlinkinadhocnetworksareitsunreliabilityanditsvariability .Thelinksinsuchanetworkareunreli ablebecauseoffading ,interference,noise,andper hapsthefailureofthetransmittingorrec…     

Connectivity of Wireless Multihop Networks in a Shadow Fading Environment

This article analyzes the connectivity of multihop radio networks in a log-normal shadow fading environment. Assuming the nodes have equal transmission capabilities and are randomly distributed according to a homogeneous Poisson process, we give a tight lower bound for the minimum node density that is necessary to obtain an almost surely connected subnetwork on a bounded area of given size. We derive an explicit expression for this bound, compute it in a variety of scenarios, and verify its tightness by simulation. The numerical results can be used for the practical design and simulation of wireless sensor and ad hoc networks. In addition, they give insight into how fading affects the topology of multihop networks. It is explained why a high fading variance helps the network to become connected.Christian Bettstetter is a senior researcher in the Future Networking Lab at DoCoMo Euro-Labs. His current research interests are in the area of self-organized networking, especially, in wireless ad hoc and sensor networks. He published several technical articles in this area and co-authored the Wiley book ‘GSM: Switching, services and protocols.’ From 1998 to 2003, he was with the Institute of Communication Networks at the Technische Universität München (TUM), where he did research and teaching on mobile communication networks, and managed a new international graduate program. Christian received the Dr.-Ing. degree (summa cum laude) and the Dipl.-Ing. degree in electrical engineering and information technology from TUM in 2004 and 1998, respectively. During his graduate studies, he worked for Wacker Siltronic, Portland, OR, USA, and wrote his master thesis on turbo decoding at the University of Notre Dame, IN, USA. He is a member of the IEEE and ACM SIGMOBILE.Christian Hartmann studied electrical engineering at the University of Karlsruhe (TH), where he received the Dipl.-Ing. degree in 1996. In 1997 he joined the Institute of Communication Networks at the Technische Universität München (TUM), where he earned the Dr.-Ing. degree (summa cum laude) in 2003. He is currently a senior researcher and member of the teaching staff at the same institution. During a research leave in the winter of 2000/2001 Christian was with the Wireless Research Lab of Lucent Bell Labs, Crawford Hill, NJ. His main research interests are in the area of mobile and wireless networks, including capacity and performance evaluation, radio resource management, modeling and simulation. He is a member of the IEEE.     

An Energy-Efficient Method for Nodes Assignment in Cluster-Based Ad Hoc Networks

One of the most critical issues in wireless ad hoc networks is represented by the limited availability of energy within network nodes. Thus, making good use of energy is a must in ad hoc networks. In this paper, we define as network lifetime the time period from the instant when the network starts functioning to the instant when the first network node runs out of energy. Our objective is to devise techniques to maximize the network lifetime in the case of cluster-based systems, which represent a significant sub-set of ad hoc networks. Cluster-based ad hoc networks comprise two types of nodes: cluster-heads and ordinary nodes. Cluster-heads coordinate all transmissions from/to ordinary nodes and forward all traffic in a cluster, either to other nodes in the cluster or to other cluster-heads. In this case, to prolong the network lifetime we must maximize the lifetime of the cluster-heads because they are the critical network element from the energy viewpoint. We propose an original approach to maximize the network lifetime by determining the optimal assignment of nodes to cluster-heads. Given the number of cluster-heads, the complexity of the proposed solution grows linearly with the number of network nodes. The network topology is assumed to be either static or slowly changing. Two working scenarios are considered. In the former, the optimal network configuration from the energy viewpoint is computed only once; in the latter, the network configuration can be periodically updated to adapt to the evolution of the cluster-heads energy status. In both scenarios, the presented solution greatly outperforms the standard assignment of nodes to cluster-heads, based on the minimum transmission power criterion.     

依据用户妥善安排的多址接入协议在分布式无线网络中的性能研究

本文基于有效竞争预约接入、无冲突轮询传输的思想提出了在多跳分布式无线网络中支持节点移动性和多跳网络结构的依据用户妥善安排的多址接入(UPMA)协议.该协议能够保证发送节点快速接入信道,从而大大提高信道的使用效率.用仿真方法研究了多跳分布式无线网络中采用该协议时的网络性能.结果表明,UPMA协议可以提供较高的通过量、较低的平均分组时延和较小的平均分组丢失率.     

基于粒子群优化的ad hoc网络最小能耗多播路由算法

在无线ad hoc网络中,设备使用电池提供能量,随着多播应用日益广泛,如何构造最小能耗多播树是一个重要问题。针对选择不同的中继节点集对构造最小能耗多播树的影响,提出了一种优化最小能耗多播树构造的离散粒子群算法。为了避免离散粒子群算法早熟收敛,引入惯性权重策略,以平衡算法的全局搜索能力和局部搜索能力。模拟实验结果表明改进后的离散粒子群算法具有较强的优化能力,有效地优化了最小能耗多播树的构造。     

Connectivity Based k-Hop Clustering in Wireless Networks

In this paper we describe several new clustering algorithms for nodes in a mobile ad hoc network. The main contribution is to generalize the cluster definition and formation algorithm so that a cluster contains all nodes that are at distance at most k hops from the clusterhead. We also describe algorithms for modifying cluster structure in the presence of topological changes. We also proposed an unified framework for most existing and new clustering algorithm where a properly defined weight at each node is the only difference in otherwise the same algorithm. This paper studied node connectivity and node ID as two particular weights, for k=1 and k=2. Finally, we propose a framework for generating random unit graphs with obstacles.     

Energy-Efficient Broadcast and Multicast Trees in Wireless Networks

The wireless networking environment presents formidable challenges to the study of broadcasting and multicasting problems. In this paper we focus on the problem of multicast tree construction, and we introduce and evaluate algorithms for tree construction in infrastructureless, all-wireless applications. The performance metric used to evaluate broadcast and multicast trees is energy-efficiency. We develop the Broadcast Incremental Power (BIP) algorithm, and adapt it to multicast operation by introducing the Multicast Incremental Power (MIP) algorithm. These algorithms exploit the broadcast nature of the wireless communication environment, and address the need for energy-efficient operation. We demonstrate that our algorithms provide better performance than algorithms that have been developed for the link-based, wired environment.     

未来战地网络的安全体制

战地网络容易受到攻击和破坏,如何实现未来战地网络中的安全通信是一个亟待解决的问题。提出了一种支持未来多层无线异构adhoc战地网络安全通信的安全体制,它具有如下性质:(1)可以在有/无基础网络设施模式下工作并无缝切换;(2)采用集中式CA签名和(t,l)门限签名体制相结合的认证方法;(3)对报文和报头分别加密;(4)可以对签名者的身份进行追踪。     

移动Ad hoc网络路由协议标准

通过重点说明互联网工程任务组(IETF)已通过的两个移动Ad hoc网络路由协议标准,使得相关工程人员在对应用于此种网络的路由协议有一个整体认识基础之上,进一步加深对移动Ad hoc网络原理的理解.     

Performance Evaluation of Routing Protocols for Ad Hoc Wireless Networks

A mobile ad hoc network is a collection of autonomous mobile nodes that communicate with each other over wireless links. Such networks are expected to play an increasingly important role in future civilian and military settings, being useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable and movement of communicating parties is possible. However, since there is no stationary infrastructure such as base stations, mobile hosts need to operate as routers in order to maintain the information about the network connectivity. Therefore, a number of routing protocols have been proposed for ad hoc wireless networks. In this paper, we study and compare the performance of the following routing protocols AODV, PAODV (preemptive AODV), CBRP, DSR, and DSDV. A variety of workload and scenarios, as characterized by mobility, load and size of the ad hoc network were simulated. Our results indicate that despite its improvement in reducing route request packets, CBRP has a higher overhead than DSR because of its periodic hello messages while AODV's end-to-end packet delay is the shortest when compared to DSR and CBRP. PAODV has shown little improvements over AODV.     

基于L-hop路由策略的无线mesh网络的吞吐量

无线mesh网络是最后一英里宽带互联网的可选技术之一。类似于ad hoe网络。在mesh网络中，每个用户节点既是通信终端又提供路由功能；用户节点以ad hoe多跳方式实现与网关的链接，通过网关可以访问因特网。无线mesh网络的吞吐量受到网关带宽的限制。为了捷高mesh网络网关频带的利用效率，现提出基于节点组织ad hoe通信方式和L-hop路由策略。在新的路由策略下，将给出对mesh网络的吞吐量的研究。     

无线传感器网络LEACH协议的研究

在无线传感器网络中,与平面路由协议相比,分簇路由协议具有一定的优势.它具有拓扑管理方便、能量利用高效.数据融合简单等优点,成为当前路由协议研究的重点.本文以低能量自适应聚类(LEACH)为例,对分簇路由协议进行了分析.在此基础上,提出改进了的LEACH ED_LEACH(Base on Energy and Di Stance factors-Low-Energy Adaptive Clustering Hierarchy),通过使用MATLAB进行了仿真,仿真结果表明ED_LEACH算法能更有效地延长网络寿命.