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.     

An Energy-Efficient Routing and Self-Organization Algorithm in Wireless Sensor Networks

1IntroductionAs the development of MEMStechnology,the microsensors whichintegrate manyfunctions such as sensing,signal processing and communication have been widelyused[1]. Wireless Sensor Network ( WSN) is construct-ed with hundreds to thousands of sensors and one ormore SINKs .Sensors can sense (monitor) many physi-cal signals such as sound,light ,electronics ,tempera-ture and humidity of the objects in a given region[2 ~3].Sensors transfer these signalsinto sensing data and sendsensin…     

A Cooperative Nearest Neighbours Topology Control Algorithm for Wireless Ad Hoc Networks

In this article, we introduce a simple distributed algorithm that assigns appropriate individual transmission powers to devices in a wireless ad hoc network. In contrast to many other proposed algorithms, it does without special hardware. It requires only local neighbourhood information and therefore avoids flooding information throughout the network. Finally, the cooperative nature of the algorithm avoids that devices cause excessive interference by using unnecessarily high transmission powers. By means of simulation, we show that the topologies created by this algorithm without any global knowledge are as effective as topologies resulting from a good choice of a common transmission power (which would require global knowledge) in terms of the achievable throughput. This work was supported in part by the German Federal Ministry of Education and Research (BMBF) as part of the IPonAir project.     

Algorithms for Energy-Efficient Multicasting in Static Ad Hoc Wireless Networks

In this paper we address the problem of multicasting in ad hoc wireless networks from the viewpoint of energy efficiency. We discuss the impact of the wireless medium on the multicasting problem and the fundamental trade-offs that arise. We propose and evaluate several algorithms for defining multicast trees for session (or connection-oriented) traffic when transceiver resources are limited. The algorithms select the relay nodes and the corresponding transmission power levels, and achieve different degrees of scalability and performance. We demonstrate that the incorporation of energy considerations into multicast algorithms can, indeed, result in improved energy efficiency.     

Ad Hoc网络路由技术

无线自组织网络(Adhoc)是一个复杂的系统,其中路由协议是该领域中的研究热点。通过采用合理的路由技术,可使无线自组网具有更为灵活的组网方式,从而达到提升网络性能、减少网络开销等目的。通过与认知无线电(CR)技术、协同通信(CC)技术以及多输入多输出(MIMO)天线技术等物理层新技术的有效结合,可以大大改善Adhoc路由协议的性能。     

一种节省能量的移动Ad Hoc网络组播选路协议

鉴于现有基于网孔的移动Ad Hoc网络组播选路协议都滑考虑如何有效使用电池能量的问题，本文提出了一种节省能量组播选路协议（E^2MRP),E^2MRP协议的两个主要特征是：（1）在创建和维护中继组（RG）的过程中交替采用分组平均能量消耗最少和最大节点花费最小两种标准，（2）采用基于图的组播结构，本文通过仿真分析大大降低了节点的能量消耗，特别是在节移动性较低，组播成员较少时更是如此。     

An Extended Dynamic Source Routing Scheme in Ad Hoc Wireless Networks

In this paper we consider a multipath extension to the dynamic source routing (DSR) protocol proposed by Johnson and Maltz, an on-demand routing protocol for ad hoc wireless networks. This extension keeps two node-disjoint paths between the source and destination of a routing process without introducing extra overhead. Unlike other multipath extensions where node-disjoint paths are selected at the destination or at the reply phase, our approach generates two node-disjoint paths during the query phase of the route discovery process by restricting the way the query packet is flooded. Several optimization options are also considered. Simulation is conducted to determine the success rate of finding node-disjoint paths.     

一种Ad Hoc网络的拓扑功率控制算法

Ad hoc网络是一种无线自组织网络，拓扑功率控制是其网络优化的核心问题之一。它能够有效降低节点间的传输功率，以提高整个网络的稳定性。文章旨在介绍一种基于节点间距离的分布式拓扑功率控制算法，通过改变网络拓扑结构，以达到节省网络能量的效果，并实现了网络中任意两节点间的K连通。     

能量受限无线Ad Hoc网络跨层设计

介绍了无线Ad Hoc网络的特点和应用,讨论了分层设计与跨层设计模式,并讨论了对有限能量的无线Ad Hoc网络跨层设计时链路层、MAC层、网络层以及应用层协议设计应考虑的因素,以及它们的交互操作。     

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.     

Energy-Efficient Routing for Connection-Oriented Traffic in Wireless Ad-Hoc Networks

We address the problem of routing connection-oriented traffic in wireless ad-hoc networks with energy efficiency. We outline the trade-offs that arise by the flexibility of wireless nodes to transmit at different power levels and define a framework for formulating the problem of session routing from the perspective of energy expenditure. A set of heuristics are developed for determining end-to-end unicast paths with sufficient bandwidth and transceiver resources, in which nodes use local information in order to select their transmission power and bandwidth allocation. We propose a set of metrics that associate each link transmission with a cost and consider both the cases of plentiful and limited bandwidth resources, the latter jointly with a set of channel allocation algorithms. Performance is measured through call blocking probability and average energy consumption and our detailed simulation model is used to evaluate the algorithms for a variety of networks.     

Checkerboard-Like Routing Protocol for Ad Hoc Mobile Wireless Networks

The main purposes of this article are to relieve broadcast problem, to immunize to some prerequisites, and to reduce the number of transmitted control packets. Broadcasting control packets network-wide is the most direct and common method for finding the required destination node in ad hoc mobile wireless networks; however, this causes a lot of waste of wireless bandwidth. To remedy the problem, routing protocols demanding some prerequisites are proposed; nonetheless, hardly can they be used if these prerequisites are missed or become stale. To efficiently reduce the number of transmitted control packets, our routing protocol partitions the network into interlaced gray districts and white districts by the aid of GPS and inhibits an intermediate node residing in a white district from re-transmitting the received control packets. However, a mobile node residing in a gray district is responsible for re-transmitting them till they reach the destination node. Our routing protocol does not demand any prerequisite except the use of GPS. Each mobile node can always obtain its own location information; furthermore, the information may neither be missed nor become stale. Our routing protocol is easy to be implemented, saves precious wireless bandwidth, and reduces almost half a number of control packets as compared with pure flooding routing protocols.Ying-Kwei Ho received the B.S. degree and M.S. degree in applied mathematics and in electrical engineering from the Chung-Cheng Institute of Technology in 1987 and 1993 respectively and the Ph.D. degree in computer engineering and science from the Yuan-Ze University, Taiwan, R.O.C. He joined the Army of Taiwan, R.O.C. in 1987 and worked as a software engineer. From 1993 to 1997, he was an instructor in the War Game Center of Armed Forces University, Taiwan, R.O.C. He is currently an assistant professor of the Department of Computer Science at Chung-Cheng Institute of Technology. His research interests include mobile computing, wireless network performance simulation and evaluation, and modeling and simulation.Ru-Sheng Liu received the B.S. degree in electrical engineering from the National Cheng-Kung University, Taiwan, in 1972 and the M.S. and Ph.D. degrees in computer science from the University of Texas at Dallas, Richardson, Texas, in 1981 and1985, respectively. He is currently an associate professor in the Department of Computer Engineering and Science at Yuan-Ze University, Chungli, Taiwan. His research interests are in the areas of mobile computing, internet technology, and computer algorithms.     

一种无线自组织网络动态路由协议

介绍了一种基于稀疏树的无线自组织网络动态路由协议,该协议采用了稀疏树路径生成算法来减少路由更新的数据量并减少网络链路的冗余,采用增量更新来降低路由协议开销并降低对传输带宽的占用,支持单向信道,采用快速路径查找算法消除网络拓扑动态变化过程中的环路与无穷计数问题。仿真结果显示它具有收敛快,开销小等特性,能够较好地适应窄带无线通信环境的需要。     

A Routing Algorithm for Wireless Ad Hoc Networks with Unidirectional Links

Most of the routing algorithms for ad hoc networks assume that all wireless links are bidirectional. In reality, some links may be unidirectional. In this paper we show that the presence of such links can jeopardize the performance of the existing distance vector routing algorithms. We also present modifications to distance vector based routing algorithms to make them work in ad hoc networks with unidirectional links. For a network of n nodes, neighbors exchange n×n matrices to propagate routing information. This results in loop-free routes.     

Localized Algorithms for Energy Efficient Topology in Wireless Ad Hoc Networks

Topology control in wireless ad hoc networks is to select a subgraph of the communication graph (when all nodes use their maximum transmission range) with some properties for energy conservation. In this paper, we propose two novel localized topology control methods for homogeneous wireless ad hoc networks. Our first method constructs a structure with the following attractive properties: power efficient, bounded node degree, and planar. Its power stretch factor is at most , and each node only has to maintain at most neighbors where the integer is an adjustable parameter, and β is a real constant between 2 and 5 depending on the wireless transmission environment. It can be constructed and maintained locally and dynamically. Moreover, by assuming that the node ID and its position can be represented in bits each for a wireless network of n nodes, we show that the structure can be constructed using at most 24n messages, where each message is bits. Our second method improves the degree bound to k, relaxes the theoretical power spanning ratio to , where is an adjustable parameter, and keeps all other properties. We show that the second structure can be constructed using at most 3n messages, where each message has size of bits. We also experimentally evaluate the performance of these new energy efficient network topologies. The theoretical results are corroborated by the simulations: these structures are more efficient in practice, compared with other known structures used in wireless ad hoc networks and are easier to construct. In addition, the power assignment based on our new structures shows low energy cost and small interference at each wireless node. The work of Xiang-Yang Li is partially supported by NSFCCR-0311174. Wen-Zhan Song received Ph.D. from Illinois Institute of Technology in 2005, BS and MS from Nanjing University of Science and Technology in 1997 and 2000. He is currently an assistant professor in Washington State University. His current research interest is mainly focus on network protocol and algorithm design, especially in wireless networks, sensor networks and Peer-to-Peer networks. He is a member of the IEEE. Yu Wang received the Ph.D. degree in computer science from Illinois Institute of Technology in 2004, the BEng degree and the MEng degree in computer science from Tsinghua University, China, in 1998 and 2000. He has been an assistant professor of computer science at the Univeristy of North Carolina at Charlotte since 2004. His current research interests include wireless networks, mobile computing, algorithm design, and artificial intelligence. He is a member of the ACM, IEEE, and IEEE Communication Society. Xiang-Yang Li has been an Assistant Professor of Computer Science at the Illinois Institute of Technology since 2000. He hold MS (2000) and PhD (2001) degree at Computer Science from University of Illinois at Urbana-Champaign. He received his Bachelor degree at Computer Science and Bachelor degree at Business Management from Tsinghua University, P.R. China in 1995. His research interests span the computational geometry, wireless ad hoc networks, game theory, cryptography and network security. He is a Member of the ACM, IEEE, and IEEE Communication Society. Ophir Frieder is the IITRI Professor of Computer Science at the Illinois Institute of Technology. His research interests span the general area of distributed information systems. He is a Member of ACM and a Fellow of the IEEE.     

Routing with Guaranteed Delivery in Ad Hoc Wireless Networks

We consider routing problems in ad hoc wireless networks modeled as unit graphs in which nodes are points in the plane and two nodes can communicate if the distance between them is less than some fixed unit. We describe the first distributed algorithms for routing that do not require duplication of packets or memory at the nodes and yet guarantee that a packet is delivered to its destination. These algorithms can be extended to yield algorithms for broadcasting and geocasting that do not require packet duplication. A byproduct of our results is a simple distributed protocol for extracting a planar subgraph of a unit graph. We also present simulation results on the performance of our algorithms.     

Route Maintenance in a Wireless Mobile Ad Hoc Network

A mobile ad-hoc network (MANET) is formed by a cluster of mobile hosts, without the infrastructure of base stations. To deal with the dynamic changing topology of a MANET, many routing protocols have been proposed. In this paper, we consider the route maintenance problem, which includes two parts: route deterioration and route breakage. In a MANET, a route may suddenly become broken because only one host roams away. Even if a route remains connected, it may become worse due to host mobility or a better route newly being formed in the system. Existing protocols, however, will stick with a fixed route once it is discovered, until it is expired or broken. In this paper, we show how to enhance several existing protocols with route optimization and local route recovery capability. So the routing paths can be adjusted on-the-fly while they are still being used for delivering packets and can be patched in minimum wireless bandwidth and delay while route errors occur.     

A Novel Routing Protocol for Supporting QoS for Ad Hoc Mobile Wireless Networks

The main purposes of this article are to lessen the influence of the fastchanging network topology, rapidly varying bandwidth information, and the increasing size of routing tables onquality of service routing. Based on DSDV (Destination-Sequenced Distance-Vector) routing protocol formaintaining up-to-date routing information, the related research has to update routing tables when networktopology changes; moreover, the routing tables must be updated periodically even though the networktopology has not changed. To put emphasis on QoS routing, they also have to exchange routing tables by thetime of bandwidth information changes. Furthermore, the size of routing tables increases with the numberof mobile nodes; therefore, the precious wireless bandwidth is wasted on transmitting the large-scalerouting tables. In this article, we propose an on-demand-based QoS routing protocol to mitigate theseproblems and to achieve the QoS requirement. The goal of this article is to discover an optimal routewith minimum time delay for transmitting real-time data from a source node hop by hop to adestination node under some predefined constraints. Our contributions are as follows: our researchprovides a rigorous bandwidth definition and bandwidth application, a broad view of bandwidth calculationand reservation, minimizing the size of control packets and the number of control packet transmissions,and an efficient QoS routing protocol.     

An Energy-Efficient Routing Protocol for Event-Driven Dense Wireless Sensor Networks

The routing energy efficiency of a wireless sensor network is a crucial issue for the network lifetime. In this article, we propose MICRO (MInimum Cost Routing with Optimized data fusion), an energy-efficient routing protocol for event-driven dense wireless sensor networks. The proposed routing protocol is an improvement over the formerly proposed LEACH and PEGASIS protocol, which is designed to be implemented mainly with node computations rather than mainly with node communications. Moreover, in the routing computation the proposed scheme exploits a new cost function for energy balancing among sensor nodes, and uses an iterative scheme with optimized data fusions to compute the minimum-cost route for each event-detecting sensor node. Compared to the PEGASIS routing protocol, MICRO substantially improves the energy-efficiency of each route, by optimizing the trade-off between minimization of the total energy consumption of each route and the balancing of the energy state of each sensor node. It is demonstrated that the proposed protocol is able to outperform the LEACH and the PEGASIS protocols with respect to network lifetime by 100–300% and 10–100%, respectively.