Ad hoc wireless distribution service

About: Ad hoc wireless distribution service is a research topic. Over the lifetime, 17734 publications have been published within this topic receiving 488205 citations.

QOLSR, QoS routing for ad hoc wireless networks using OLSR

Abstract: This paper describes a novel quality-of-service (QoS) routing protocol for ad hoc networks based on the OLSR protocol. Our protocol, QOLSR, is designed for wireless networks with stationary or moving nodes, where each node is equipped with 802.11 wireless card. The goal of our protocol is not only to find a route from a source to a destination, but an optimal route that satisfies the end-to-end QoS requirement, often given in terms of bandwidth or delay. We present an analytical model to compute the average delay and permissible throughput on links using the IEEE 802.11 medium access protocol and considering correlations and interferences between nodes. This model takes into account packet's collision probability, node's MAC queuing and service times based on the IEEE 802.11 binary exponential backoff algorithm and the events underneath its operation. Afterwards, our protocol assigns weights to individual links based on the average delay and bandwidth metrics of packets over the link. We present a distributed algorithm for multiple QoS requirements to find the source destination optimal paths in terms of bandwidth and delay using the known partial network topology available on each node. However, these optimal paths in partial network topology are not optimal paths in the whole ad hoc network. We show that this problem is due to the heuristic for the selection of MPRs used in OLSR. We propose innovative heuristics for the selection of MPRs based on QoS measurements that allow QOLSR to find optimal paths on the known partial topology having the same bandwidth performances that those on the whole network. The performance evaluation of our protocol in both static and dynamic ad hoc networks is extensively investigated. Mathematical analysis and simulation results show that the QOLSR protocol yields better performance compared to the best-effort OLSR protocol and significantly improves throughput by using our proposed heuristic. Copyright © 2005 AEIT.

On the Routing Problem in Disconnected Vehicular Ad-hoc Networks

Abstract: Vehicular ad hoc wireless network (VANET) exhibits a bipolar behavior in terms of network topology: fully connected topology with high traffic volume or sparsely connected topology when traffic volume is low. In this work, we develop a statistical traffic model based on the data collected on 1-80 freeway in California in order to study key performance metrics of interest in disconnected VANETs, such as average re-healing time (or the network restoration time). Our results show that, depending on the sparsity of vehicles, the network re-healing time can vary from a few seconds to several minutes. This suggests that, a new ad hoc routing protocol will be needed as the conventional ad hoc routing protocols such as dynamic source routing (DSR) and ad hoc on-demand distance vector routing (AODV) will not work with such long re-healing times.

Robust content dissemination in disrupted environments

Abstract: Content dissemination in disrupted networks poses a big challenge, given that the current routing architectures of ad hoc networks require establishing routes from sources to destinations before content can disseminated between them. In ad hoc networks subject to disruption, lack of reliable connectivity between producers and consumers of information makes most routing protocols perform very poorly or not work at all. We present DIRECT (DIsruption REsilient Content Transport), which is a content dissemination approach for ad hoc networks that exploits in-network storage and the hop-by-hop dissemination of named information objects. Simulation experiments illustrate that DIRECT provides a high degree of reliability while maintaining low levels of delivery latencies and signaling and data overhead compared to traditional on-demand routing and epidemic routing.

K-clustering in wireless ad hoc networks

Abstract: Ad hoc networks consist of wireless hosts that communicate with each other in the absence of a fixed infrastructure. Clustering is commonly used in order to limit the amount of routing information stored and maintained at individual hosts. A k-clustering is a framework in which the wireless network is divided into non-overlapping sub networks, also referred to as clusters, and where every two wireless hosts in a sub network are at most k hops from each other. The algorithmic complexity of k-clustering is known to be NP-Complete for simple undirected graphs. For the special family of graphs that represent ad hoc wireless networks, modeled as unit disk graphs, we introduce a two phase distributed polynomial time and message complexity approximation solution with O(k) worst case ratio over the optimal solution. The first phase constructs a spanning tree of the network and the second phase then partitions the spanning tree into subtrees with bounded diameters.

Report on a working session on security in wireless ad hoc networks

Abstract: Levente Buttyan Jean-Pierre Hubaux´levente.buttyan@epfl.ch jean-pierre.hubaux@epfl.chLaboratory for Computer Communications and ApplicationsSwiss Federal Institute of Technology – Lausanne (EPFL), SwitzerlandOn June 12, 2002, we organized a working session de-voted to the topic of security in wireless ad hoc networks.This event took place on our campus the day after MobiHoc2002 and attracted around twenty persons in an informalsetting.Securing wireless ad hoc networks is particularly diffi-cult for many reasons including the following: