Energy-aware self stabilization in mobile ad hoc networks : A multicasting case study

Dynamic networks, e.g. Mobile Ad Hoc Networks (MANETs), call for adaptive protocols that can tolerate topological changes due to nodes ’ mobility and depletion of battery power. Also proactivity in these protocols is essential to ensure low latency. Self-stabilization techniques for distributed systems provide both adaptivity and proactivity to make it suitable for the MANETs. However, energyefficiency- a prime concern in MANETs with batterypowered nodes- is not guaranteed by self-stabilization. In this paper, we propose a node-based energy metric that minimizes the energy consumption of the multicast tree by taking into account the overhearing cost. We apply the metric to Self-Stabilizing Shortest Path Spanning Tree (SS-SPST) protocol to obtain energy-aware SS-SPST (SS-SPST-E). Using simulations, we study the energy-latency tradeoff by comparing SS-SPST-E with SS-SPST and other MANET multicast protocols, such as ODMRP and MAODV.

Routing Strategies for Capacity Enhancement in Multi-hop Wireless Ad Hoc Networks

This thesis examines a Distributed Interference Impact Probing (DIIP) strategy for Wireless Ad hoc Networks (WANETs), using a novel cross-layer Minimum Impact Routing (MIR) protocol. Perfonnance is judged in tenns of interference reduction ratio, efficiency, and system and user capacity, which are calculated based on the measurement of Disturbed Nodes (DN). A large number of routing algorithms have been proposed with distinctive features aimed to overcome WANET's fundamental challenges, such as routing over a dynamic topology, scheduling broadcast signals using dynamic Media Access Control (MAC), and constraints on network scalability. However, the scalability problem ofWANET cannot simply adapt the frequency reuse mechanism designed for traditional stationary cellular networks due to the relay burden, and there is no single comprehensive algorithm proposed for it. DIIP enhances system and user capacity using a cross layer routing algorithm, MIR, using feedback from DIIP to balance transmit power in order to control hop length, which consequently changes the number of relays along the path. This maximizes the number of simultaneous transmitting nodes, and minimizes the interference impact, i.e. measured in tenns of 'disturbed nodes'. The perfonnance of MIR is examined compared with simple shortest-path routing. A WANET simulation model is configured to simulate both routing algorithms under multiple scenarios. The analysis has shown that once the transmitting range of a node changes, the total number of disturbed nodes along a path changes accordingly, hence the system and user capacity varies with interference impact variation. By carefully selecting a suitable link length, the neighbouring node density can be adjusted to reduce the total number of DN, and thereby allowing a higher spatial reuse ratio. In this case the system capacity can increase significantly as the number of nodes increases. In contrast, if the link length is chosen regardless ofthe negative impact of interference, capacity decreases. In addition, MIR diverts traffic from congested areas, such as the central part of a network or bottleneck points

Impact of directional antennas on routing and neighbor discovery in wireless ad-hoc networks

Wireless ad-hoc networks are data networks that are deployed without a fixed infrastructure nor central controllers such as access points or base stations. In these networks, data packets are forwarded directly to the destination node if they are within the transmission range of the sender or sent through a multi-hop path of intermediary nodes that act as relays. This paradigm where a fixed infrastructure is not needed, is tolerant to topology changes and allows a fast deployment have been considered as a promissory technology that is suitable for a large number of network implementations, such as mobile hand-held devices, wireless sensors, disaster recovery networks, etc. Recently, smart directional antennas have been identified as a robust technology that can boost the performance of wireless ad-hoc networks in terms of coverage, connectivity, and capacity. Contrary to omnidirectional antennas, which can radiate energy in all directions, directional antennas can focus the energy in a specific direction, extending the coverage range for the same power level. Longer ranges provide shorter paths to destination nodes and also improve connectivity. Moreover, directional antennas can reduce the number of collisions in a contention-based access scheme as they can steer the main lobe in the desired direction and set nulls in all the others, thereby they minimize the co-channel interference and reduce the noise level. Connections are more reliable due to the increased link stability and spatial diversity. Shorter paths, as well as alternative paths, are also available as a consequence of the use of directional antennas. All these features combined results in a higher network capacity. Most of the previous research has focused on adapting the existing medium access control and routing protocols to utilize directional communications. This research work is novel because it improves the neighbor discovery process as it allows to discover nodes in the second neighborhood of a given node using a gossip based procedure and by sharing the relative position information obtained during this stage with the routing protocol with the aim of reducing the number of hops between source and destination. We have also developed a model to evaluate the energy consumed by the nodes when smart directional antennas are used in the ad-hoc network. This study has demonstrated that by adapting the beamwidth of the antennas nodes are able to reach furthest nodes and consequently, reduce the number of hops between source and destination. This fact not only reduces the end-to-end delay and improves the network throughput but also reduces the average energy consumed by the whole network

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

On Maximizing Network Lifetime of Broadcast in WANETs under an Overhearing Cost Model

guofeng.deng,sandeep.gupta¡ Abstract. Absence of line power supplies imposes severe constraints on nodes in wireless ad hoc and sensor networks. In this paper, we concentrate on finding a broadcast tree that maximizes the network’s lifetime. Previous studies showed that this problem is polynomially solvable when assuming the receiver consumes no energy or only the designated receiver consumes energy for receiving packets. Due to the broadcast nature of the wireless medium, however, unintended active nodes in the receiving range of a transmitting node may overhear the message and hence contribute to energy wastage. Under the overhearing cost model, the problem becomes NP-hard and the approximation ratio of the existing solutions under the non-overhearing cost model can be as bad as ¢¤£¦¥¨ §. We investigate the problem by developing heuristic solutions. Simulation results show that our algorithms outperform the existing algorithms by up to 100%.