7,786 research outputs found
A link-state based on-demand routing protocol supporting real-time traffic for wireless mobile ad hoc networks
Ankara : The Department of Computer Engineering and the Institute of Engineering and Science of Bilkent University, 2007.Thesis (Master's) -- Bilkent University, 2007.Includes bibliographical references leaves 200-212.Wireless ad hoc networks have gained a lot of popularity since their introduction
and as many wireless network interface cards provide support for ad hoc
networking, such networks have also seen real-life deployment for non-specialized
purposes. Wireless mobile ad hoc networks (MANETs) are currently the most
common type of ad hoc networks, and such networks are especially esteemed for
their mobility support and ease of deployment due to their ad hoc nature. As
most common network applications, such as the Web, FTP, email, and instant
messaging, are data-centric and do not operate under strict time constraints,
MANETs have been deployed to enable such non-real-time applications in the
past. However, with the increasing use of real-time applications over ad hoc
networks, such as teleconferencing, VoIP, and security and tracking applications
where timeliness is of importance, real-time traffic support in multi-hop wireless
mobile ad hoc networks has become an issue.
We propose an event-driven, link-state based, on-demand routing protocol to
enable real-time traffic support in such multi-hop wireless mobile ad hoc networks.
Our protocol, which is named Elessar, is based on link-state topology
dissemination, but instead of the more common periodic link-state messaging
scheme, we employ event-driven link-state messages in Elessar, where topology
changes are the events of interest. Through such an approach, we aim to lower the
overhead of our protocol, especially for low-mobility cases, which is currently the
most commonly encountered case with ad hoc networks deployed with machines
directly interacting with humans, such as PDAs and laptops. Due to its link-state
nature, our protocol is able to support non-real-time traffic without any further
action. In order to support real-time traffic, however, we employ a direct cost
dissemination mechanism, which only operates on-demand when there are one or
more real-time flows in the network. We aim to provide soft quality-of-service
(QoS) guarantees to real-time flows through intelligent path selection, without
any resource reservation. We also aim to provide such QoS guarantees throughout
the lifetime of a real-time flow, even in the face of node failures and mobility,
by dynamic path adaptation during the lifetime of the flow. Elessar is able to
support real-time and non-real-time traffic concurrently, as well as various different
types of concurrent real-time traffic, such as delay- and loss-sensitive traffic.
Our protocol, therefore, does not aim to support a single type of real-time traffic,
but rather a plethora of different types of real-time traffic. Elessar is completely
distributed, dynamic and adaptive, and does not require the underlying MAC
protocol to be QoS-aware.
We analyse our design choices and the performance of our protocol through
realistic simulation experiments conducted on the OMNeT++ discrete event simulation
platform, using the INET framework. We have used the IEEE 802.11b
MAC protocol during our simulations and have employed the random waypoint
mobility model to simulate mobility. Our experimental results show that Elessar
is able to efficiently provide real-time traffic support for different types of traf-
fic flows, even in the face of mobility. Our protocol operates best for smallto-medium-sized
networks where mobility rates are low-to-medium. Once the
mobility rate exceeds a certain threshold, intelligent path selection cannot cope
satisfactorily with the high dynamism of the environment and the overhead of
Elessar exceeds acceptable levels due to its event-driven link-state nature.Görbil, GökçeM.S
On the Experimental Evaluation of Vehicular Networks: Issues, Requirements and Methodology Applied to a Real Use Case
One of the most challenging fields in vehicular communications has been the
experimental assessment of protocols and novel technologies. Researchers
usually tend to simulate vehicular scenarios and/or partially validate new
contributions in the area by using constrained testbeds and carrying out minor
tests. In this line, the present work reviews the issues that pioneers in the
area of vehicular communications and, in general, in telematics, have to deal
with if they want to perform a good evaluation campaign by real testing. The
key needs for a good experimental evaluation is the use of proper software
tools for gathering testing data, post-processing and generating relevant
figures of merit and, finally, properly showing the most important results. For
this reason, a key contribution of this paper is the presentation of an
evaluation environment called AnaVANET, which covers the previous needs. By
using this tool and presenting a reference case of study, a generic testing
methodology is described and applied. This way, the usage of the IPv6 protocol
over a vehicle-to-vehicle routing protocol, and supporting IETF-based network
mobility, is tested at the same time the main features of the AnaVANET system
are presented. This work contributes in laying the foundations for a proper
experimental evaluation of vehicular networks and will be useful for many
researchers in the area.Comment: in EAI Endorsed Transactions on Industrial Networks and Intelligent
Systems, 201
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