67,054 research outputs found
Swarm intelligence and its applications to wireless ad hoc and sensor networks.
Swarm intelligence, as inspired by natural biological swarms, has numerous powerful
properties for distributed problem solving in complex real world applications such
as optimisation and control. Swarm intelligence properties can be found in natural
systems such as ants, bees and birds, whereby the collective behaviour of unsophisticated
agents interact locally with their environment to explore collective problem solving
without centralised control. Recent advances in wireless communication and digital
electronics have instigated important changes in distributed computing. Pervasive
computing environments have emerged, such as large scale communication networks
and wireless ad hoc and sensor networks that are extremely dynamic and unreliable.
The network management and control must be based on distributed principles where
centralised approaches may not be suitable for exploiting the enormous potential of
these environments. In this thesis, we focus on applying swarm intelligence to the
wireless ad hoc and sensor networks optimisation and control problems.
Firstly, an analysis of the recently proposed particle swarm optimisation, which is
based on the swarm intelligence techniques, is presented. Previous stability analysis
of the particle swarm optimisation was restricted to the assumption that all of the
parameters are non random since the theoretical analysis with the random parameters
is difficult. We analyse the stability of the particle dynamics without these restrictive
assumptions using Lyapunov stability and passive systems concepts. The particle
swarm optimisation is then used to solve the sink node placement problem in sensor
networks.
Secondly, swarm intelligence based routing methods for mobile ad hoc networks
are investigated. Two protocols have been proposed based on the foraging behaviour
of biological ants and implemented in the NS2 network simulator. The first protocol
allows each node in the network to choose the next node for packets to be
forwarded on the basis of mobility influenced routing table. Since mobility is one of
the most important factors for route changes in mobile ad hoc networks, the mobility
of the neighbour node using HELLO packets is predicted and then translated into a
pheromone decay as found in natural biological systems. The second protocol uses
the same mechanism as the first, but instead of mobility the neighbour node remaining
energy level and its drain rate are used. The thesis clearly shows that swarm
intelligence methods have a very useful role to play in the management and control
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problems associated with wireless ad hoc and sensor networks. This thesis has given
a number of example applications and has demonstrated its usefulness in improving
performance over other existing methods
Spatial networks with wireless applications
Many networks have nodes located in physical space, with links more common
between closely spaced pairs of nodes. For example, the nodes could be wireless
devices and links communication channels in a wireless mesh network. We
describe recent work involving such networks, considering effects due to the
geometry (convex,non-convex, and fractal), node distribution,
distance-dependent link probability, mobility, directivity and interference.Comment: Review article- an amended version with a new title from the origina
Virtual Communication Stack: Towards Building Integrated Simulator of Mobile Ad Hoc Network-based Infrastructure for Disaster Response Scenarios
Responses to disastrous events are a challenging problem, because of possible
damages on communication infrastructures. For instance, after a natural
disaster, infrastructures might be entirely destroyed. Different network
paradigms were proposed in the literature in order to deploy adhoc network, and
allow dealing with the lack of communications. However, all these solutions
focus only on the performance of the network itself, without taking into
account the specificities and heterogeneity of the components which use it.
This comes from the difficulty to integrate models with different levels of
abstraction. Consequently, verification and validation of adhoc protocols
cannot guarantee that the different systems will work as expected in
operational conditions. However, the DEVS theory provides some mechanisms to
allow integration of models with different natures. This paper proposes an
integrated simulation architecture based on DEVS which improves the accuracy of
ad hoc infrastructure simulators in the case of disaster response scenarios.Comment: Preprint. Unpublishe
Achieving Small World Properties using Bio-Inspired Techniques in Wireless Networks
It is highly desirable and challenging for a wireless ad hoc network to have
self-organization properties in order to achieve network wide characteristics.
Studies have shown that Small World properties, primarily low average path
length and high clustering coefficient, are desired properties for networks in
general. However, due to the spatial nature of the wireless networks, achieving
small world properties remains highly challenging. Studies also show that,
wireless ad hoc networks with small world properties show a degree distribution
that lies between geometric and power law. In this paper, we show that in a
wireless ad hoc network with non-uniform node density with only local
information, we can significantly reduce the average path length and retain the
clustering coefficient. To achieve our goal, our algorithm first identifies
logical regions using Lateral Inhibition technique, then identifies the nodes
that beamform and finally the beam properties using Flocking. We use Lateral
Inhibition and Flocking because they enable us to use local state information
as opposed to other techniques. We support our work with simulation results and
analysis, which show that a reduction of up to 40% can be achieved for a
high-density network. We also show the effect of hopcount used to create
regions on average path length, clustering coefficient and connectivity.Comment: Accepted for publication: Special Issue on Security and Performance
of Networks and Clouds (The Computer Journal
Time-Varying Graphs and Dynamic Networks
The past few years have seen intensive research efforts carried out in some
apparently unrelated areas of dynamic systems -- delay-tolerant networks,
opportunistic-mobility networks, social networks -- obtaining closely related
insights. Indeed, the concepts discovered in these investigations can be viewed
as parts of the same conceptual universe; and the formal models proposed so far
to express some specific concepts are components of a larger formal description
of this universe. The main contribution of this paper is to integrate the vast
collection of concepts, formalisms, and results found in the literature into a
unified framework, which we call TVG (for time-varying graphs). Using this
framework, it is possible to express directly in the same formalism not only
the concepts common to all those different areas, but also those specific to
each. Based on this definitional work, employing both existing results and
original observations, we present a hierarchical classification of TVGs; each
class corresponds to a significant property examined in the distributed
computing literature. We then examine how TVGs can be used to study the
evolution of network properties, and propose different techniques, depending on
whether the indicators for these properties are a-temporal (as in the majority
of existing studies) or temporal. Finally, we briefly discuss the introduction
of randomness in TVGs.Comment: A short version appeared in ADHOC-NOW'11. This version is to be
published in Internation Journal of Parallel, Emergent and Distributed
System
Implementation of CAVENET and its usage for performance evaluation of AODV, OLSR and DYMO protocols in vehicular networks
Vehicle Ad-hoc Network (VANET) is a kind of Mobile Ad-hoc Network (MANET) that establishes wireless connection between cars. In VANETs and MANETs, the topology of the network changes very often, therefore implementation of efficient routing protocols is very important problem. In MANETs, the Random Waypoint (RW) model is used as a simulation model for generating node mobility pattern. On the other hand, in VANETs, the mobility patterns of nodes is restricted along the roads, and is affected by the movement of neighbour nodes. In this paper, we present a simulation system for VANET called CAVENET (Cellular Automaton based VEhicular NETwork). In CAVENET, the mobility patterns of nodes are generated by an 1-dimensional cellular automata. We improved CAVENET and implemented some routing protocols. We investigated the performance of the implemented routing protocols by CAVENET. The simulation results have shown that DYMO protocol has better performance than AODV and OLSR protocols.Peer ReviewedPostprint (published version
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