http://cpham.perso.univ-pau.fr/ENSEIGNEMENT/PAU-UPPA/RESA-M2/Clustering-abasi.pdf

A survey on clustering algorithms for wireless sensor networks

This paper presents Span, a power saving technique for multi-hop ad hoc wireless networks that reduces energy consumption without significantly diminishing the capacity or connectivity of the network. Span builds on the observation that when a region of a shared-channel wireless network bag a sufficient density of nodes, only a small number of them need be on at any time to forward traffic for active connections.Span is a distributed, randomized algorithm where nodes make local decisions on whether to sleep, or to join a forwarding backbone as a coordinator. Each node bases its decision on an estimate of how many of its neighbors will benefit from it being awake, and the amount of energy available to it. We give a randomized algorithm where coordinators rotate with time, demonstrating how localized node decisions lead to a connected, capacity-preserving global topology.Improvement in system lifetime due to Span increases as the ratio of idle-to-sleep energy consumption increases, and increases as the density of the network increases. For example, our simulations show that with a practical energy model, system lifetime of an 802.11 network in power saving mode with Span is a factor of two better than without. Span integrates nicely with 802.11—when run in conjunction with the 802.11 power saving mode, Span improves communication latency, capacity, and system lifetime.

https://www.cs.ucla.edu/classes/fall03/cs218/paper/p85-chen.pdf

Span: An energy-efficient coordination algorithm for topology maintenance in Ad Hoc wireless networks

A method for providing a search result list. The method includes receiving a search request from a searcher (12). In a database of search listings (24) in which each search listing is associated with an advertiser (30) and includes at least one search term and a bid amount by the advertiser, search listings generating a match with the search request are identified. A predetermined number of identified search listings (38) are selected according to bid amount for display to the searcher (16). The identified search listings are arranged for display in a random order as the search result list. The search result list is then communicated to the searcher.

Improved system and method for influencing a position on a search result list generated by a computer network search engine

This paper presents Span, a power saving technique for multi-hop ad hoc wireless networks that reduces energy consumption without significantly diminishing the capacity or connectivity of the network. Span builds on the observation that when a region of a sharedchannel wireless network has a sufficient density of nodes, only a small number of them need be on at any time to forward traffic for active connections. Span is a distributed, randomized algorithm where nodes make local decisions on whether to sleep, or to join a forwarding backbone as a coordinator. Each node bases its decision on an estimate of how many of its neighbors will benefit from it being awake, and the amount of energy available to it. We give a randomized algorithm where coordinators rotate with time, demonstrating how localized node decisions lead to a connected, capacity-preserving global topology. Improvement in system lifetime due to Span increases as the ratio of idle-to-sleep energy consumption increases. Our simulations show that with a practical energy model, system lifetime of an 802.11 network in power saving mode with Span is a factor of two better than without. Additionally, Span also improves communication latency and capacity.

Span: an energy-efficient coordination algorithm for topology maintenance in ad hoc wireless networks

Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, ‘‘ad-hoc’’ network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, e.g., disaster recovery environments. Ad hoc networking concept is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad hoc paradigm. Recently, the introduction of new technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent evolutions have been generating a renewed and growing interest in the research and development of MANET. This paper attempts to provide a comprehensive overview of this dynamic field. It first explains the important role that mobile ad hoc networks play in the evolution of future wireless technologies. Then, it reviews the latest research activities in these areas, including a summary of MANETs characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future. � 2003 Elsevier B.V. All rights reserved.

/pdf/mobile-ad-hoc-networking-imperatives-and-challenges-56mord86q0.pdf

Mobile ad hoc networking: imperatives and challenges

Efficient routing among a set of mobile hosts is one of the most important functions in ad hoc wireless networks. Routing based on a connected dominating set is a promising approach, where the search space for a route is reduced to the hosts in the set. A set is dominating if all the hosts in the system are either in the set or neighbors of hosts in the set. The efficiency of dominating-set-based routing mainly depends on the overhead introduced in the formation of the dominating set and the size of the dominating set. In this paper, we first review a localized formation of a connected dominating set called marking process and dominating-set-based routing. Then, we propose a dominant pruning rule to reduce the size of the dominating set. This dominant pruning rule (called Rule k) is a generalization of two existing rules (called Rule 1 and Rule 2, respectively). We prove that the vertex set derived by applying Rule k is still a connected dominating set. Rule k is more effective in reducing the dominating set derived from the marking process than the combination of Rules 1 and 2 and, surprisingly, in a restricted implementation with local neighborhood information, Rule k has the same communication complexity and less computation complexity. Simulation results confirm that Rule k outperforms Rules 1 and 2, especially in networks with relatively high vertex degree and high percentage of unidirectional links. We also prove that an upper bound exists on the average size of the dominating set derived from Rule k in its restricted implementation.

/pdf/an-extended-localized-algorithm-for-connected-dominating-set-nznskre8jb.pdf

An extended localized algorithm for connected dominating set formation in ad hoc wireless networks

Efficient routing among a set of mobile hosts (also called nodes) is one of the most important functions in ad hoc wireless networks. Routing based on a connected dominating set is a promising approach, where the searching space for a route is reduced to nodes in the set. A set is dominating if all the nodes in the system are either in the set or neighbors of nodes in the set. J. Wu and H. Li (1999) proposed a simple and efficient distributed algorithm for calculating connected dominating set in ad hoc wireless networks, where connections of nodes are determined by geographical distances of nodes. In general, nodes in the connected dominating set consume more energy in order to handle various bypass traffics than nodes outside the set. To prolong the life span of each node, and hence, the network by balancing the energy consumption in the network, nodes should be alternated in being chosen to form a connected dominating set. In this paper, we propose a method of calculating power-aware connected dominating set. Our simulation results show that the proposed approach outperforms several existing approaches in terms of life span of the network.

/pdf/on-calculating-power-aware-connected-dominating-sets-for-33i2znoo1r.pdf

On calculating power-aware connected dominating sets for efficient routing in ad hoc wireless networks

We propose a general framework for broadcasting in ad hoc networks through self-pruning. The approach is based on selecting a small subset of hosts (also called nodes) to form a forward node set to carry out a broadcast process. Each node, upon receiving a broadcast packet, determines whether to forward the packet based on two neighborhood coverage conditions. These coverage conditions depend on neighbor connectivity and history of visited nodes, and in general, resort to global network information. Using local information such as k-hop neighborhood information, the forward node set is selected through a distributed and local pruning process. The forward node set can be constructed and maintained through either a proactive process (i.e., "up-to-date") or a reactive process (i.e., "on-the-fly"). Several existing broadcast algorithms can be viewed as special cases of the coverage conditions with k-hop neighborhood information. Simulation results show that new algorithms, which are more efficient than existing ones, can be derived from the coverage conditions, and self-pruning based on 2- or 3-hop neighborhood information is relatively cost-effective.

/pdf/broadcasting-in-ad-hoc-networks-based-on-self-pruning-39d7swfskj.pdf

Broadcasting in ad hoc networks based on self-pruning

We propose a general framework for broadcasting in ad hoc networks through self-pruning. The approach is based on selecting a small subset of hosts (also called nodes) to form a forward node set on carry out a broadcast process. Each node, upon receiving a broadcast packet, determines whether to forward the packet or not based on two neighborhood coverage conditions proposed in this paper. These coverage conditions depend on neighbor connectivity and history of visited nodes, and in general, resort to global network information. Using local information such as k-hop neighborhood information, the forward node set is selected through a distributed and local pruning process. The forward node set can be constructed and maintained through either a proactive process (i.e., "up-to-date") or a reactive process (i.e., "on-the-fly"). Several existing broadcast algorithms can be viewed as special cases of the coverage conditions with k-hop neighborhood information. Simulation results show that new algorithms, which are more efficient than existing ones, can be derived from the coverage conditions, and self-pruning based on 2- or 3-hop neighborhood information is relatively more cost-effective.

/pdf/broadcasting-in-ad-hoc-networks-based-on-self-pruning-d718vygj7t.pdf

We propose a generic framework for distributed broadcasting in ad hoc wireless networks. The approach is based on selecting a small subset of nodes to form a forward node set to carry out a broadcast process. The status of each node, forward or nonforward, is determined either by the node itself or by other nodes. Node status can be determined at different snapshots of network state along time (called views) without causing problems in broadcast coverage. Therefore, the forward node set can be constructed and maintained through either a proactive process (i.e., "up-to-date") before the broadcast process or a reactive process (i.e., "on-the-fly") during the broadcast process. A sufficient condition, called coverage condition, is given for a node to take the nonforward status. Such a condition can be easily checked locally around the node. Several existing broadcast algorithms can be viewed as special cases of the generic framework with k-hop neighborhood information. A comprehensive comparison among existing algorithms is conducted. Simulation results show that new algorithms, which are more efficient than existing ones, can be derived from the generic framework.

Fei Dai

Papers

An extended localized algorithm for connected dominating set formation in ad hoc wireless networks

On calculating power-aware connected dominating sets for efficient routing in ad hoc wireless networks

Broadcasting in ad hoc networks based on self-pruning

Broadcasting in ad hoc networks based on self-pruning

A generic distributed broadcast scheme in ad hoc wireless networks