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.

Secure Extension to the OLSR protocol

Abstract: In this paper we present a mechanism for securing the OLSR protocol. This mechanism is implemented as an extension to the OLSR source code provided from UniK (www.olsr.org), and can be downloaded freely from the Internet. The proposed and implemented mechanism is based on signing each OLSR control packet with a digital signature for authenticating this message. Also, the mechanism provides a timestamp exchange process. The timestamps are used to prevent replay attacks on the routing protocol. This security mechanism does not need synchronized time.

Topology and mobility considerations in mobile ad hoc networks

Abstract: A highly dynamic topology is a distinguishing feature and challenge of a mobile ad hoc network. Links between nodes are created and broken, as the nodes move within the network. This node mobility affects not only the source and/or destination, as in a conventional wireless network, but also intermediate nodes, due to the network's multihop nature. The resulting routes can be extremely volatile, making successful ad hoc routing dependent on efficiently reacting to these topology changes. In order to better understand this environment, a number of characteristics have been studied concerning the links and routes that make up an ad hoc network. Several network parameters are examined, including number of nodes, network dimensions, and radio transmission range, as well as mobility parameters for maximum speed and wait times. In addition to suggesting guidelines for the evaluation of ad hoc networks, the results reveal several properties that should be considered in the design and optimization of MANET protocols.

Adaptive routing in ad hoc wireless multi-hop networks

Abstract: Ad hoc wireless multi-hop networks (AHWMNs) are communication networks that consist entirely of wireless nodes, placed together in an ad hoc manner, i.e. with minimal prior planning. All nodes have routing capabilities, and forward data packets for other nodes in multi-hop fashion. Nodes can enter or leave the network at any time, and may be mobile, so that the network topology continuously experiences alterations during deployment. AHWMNs pose substantially different challenges to networking protocols than more traditional wired networks. These challenges arise from the dynamic and unplanned nature of these networks, from the inherent unreliability of wireless communication, from the limited resources available in terms of bandwidth, processing capacity, etc., and from the possibly large scale of these networks. Due to these different challenges, new algorithms are needed at all layers of the network protocol stack. We investigate the issue of adaptive routing in AHWMNs, using ideas from artificial intelligence (AI). Our main source of inspiration is the field of Ant Colony Optimization (ACO). This is a branch of AI that takes its inspiration from the behavior of ants in nature. ACO has been applied to a wide range of different problems, often giving state-of-the-art results. The application of ACO to the problem of routing in AHWMNs is interesting because ACO algorithms tend to provide properties such as adaptivity and robustness, which are needed to deal with the challenges present in AHWMNs. On the other hand, the field of AHWMNs forms an interesting new application domain in which the ideas of ACO can be tested and improved. In particular, we investigate the combination of ACO mechanisms with other techniques from AI to get a powerful algorithm for the problem at hand. We present the AntHocNet routing algorithm, which combines ideas from ACO routing with techniques from dynamic programming and other mechanisms taken from more traditional routing algorithms. The algorithm has a hybrid architecture, combining both reactive and proactive mechanisms. Through a series of simulation tests, we show that for a wide range of different environments and performance metrics, AntHocNet can outperform important reference algorithms in the research area. We provide an extensive investigation of the internal working of the algorithm, and we also carry out a detailed simulation study in a realistic urban environment. Finally, we discuss the implementation of ACO routing algorithms in a real world testbed.

Bounds on hop distance in greedy routing approach in wireless ad hoc networks

Abstract: Wireless ad hoc networks are generally characterised by random node locations and multi-hop routes. A quantitative knowledge of the relation between hop count and Euclidean distance could provide a better understanding of important network parameters such as end-to-end delay, power consumption along the route, and node localisation. In this paper, we present an analytic approach to capture the statistics on hop count for a given source-to-destination Euclidean distance in a greedy routing approach. We also show that, for a given hop count, the bounds on Euclidean distance can be computed from the distribution characteristics of per-hop progress.

A unified analysis of routing protocols in MANETs

Abstract: This paper presents a mathematical framework for the evaluation of the performance of proactive and reactive routing protocols in mobile ad hoc networks (MANETs). This unified framework provides a parametric view of protocol performance, which in turn provides a deeper insight into protocol operations and reveals the compounding and interacting effects of protocol logic and network parameters. The parametric model comes from a combinatorial model, where the routing logic is synthesized along with the characterization of MAC performance. Each wireless node is seen independently as a two-customer queue without priority, where the two types of customers are unicast and broadcast packets. The model captures the essential behavior and scalability limits in network size of both classes of routing protocols, and provides valuable guidance on the performance of reactive or proactive routing protocols under various network configurations and mobility conditions. The analytical results obtained with the proposed model are in close agreement with simulation results obtained from discrete-event Qualnet simulations.