15,652 research outputs found
Techniques for locating service faults in mobile ad hoc networks
Fault localization in general refers to a technique for identifying the likely root causes of failures observed in systems formed from components. Fault localization in systems deployed on mobile ad hoc networks (MANETs) is a particularly challenging task because those systems are subject to a wider variety and higher incidence of faults than those deployed in xed networks, the resources available to track fault symptoms are severely limited, and many of the sources of faults in MANETs are by their nature transient. We present a method for localizing the faults occurring in service-based systems hosted on MANETs. The method is based on the use of dependence data that are discovered dynamically through decentralized observations of service interactions. We employ both Bayesian and timing-based reasoning techniques to analyze the data in the context of a speci c fault propagation model, deriving a ranked list of candidate fault locations. We present the results of an extensive set of experiments exploring a wide range of operational conditions to evaluate the accuracy of our method
Reliability of Mobile Agents for Reliable Service Discovery Protocol in MANET
Recently mobile agents are used to discover services in mobile ad-hoc network
(MANET) where agents travel through the network, collecting and sometimes
spreading the dynamically changing service information. But it is important to
investigate how reliable the agents are for this application as the
dependability issues(reliability and availability) of MANET are highly affected
by its dynamic nature.The complexity of underlying MANET makes it hard to
obtain the route reliability of the mobile agent systems (MAS); instead we
estimate it using Monte Carlo simulation. Thus an algorithm for estimating the
task route reliability of MAS (deployed for discovering services) is proposed,
that takes into account the effect of node mobility in MANET. That mobility
pattern of the nodes affects the MAS performance is also shown by considering
different mobility models. Multipath propagation effect of radio signal is
considered to decide link existence. Transient link errors are also considered.
Finally we propose a metric to calculate the reliability of service discovery
protocol and see how MAS performance affects the protocol reliability. The
experimental results show the robustness of the proposed algorithm. Here the
optimum value of network bandwidth (needed to support the agents) is calculated
for our application. However the reliability of MAS is highly dependent on link
failure probability
Simulation and Performance Analysis of MP-OLSR for Mobile Ad hoc Networks
Mobile ad hoc networks (MANETs) consist of a collection of wireless mobile
nodes which dynamically exchange data without reliance on a fixed base station
or a wired backbone network, which makes routing a crucial issue for the design
of a ad hoc networks. In this paper we discussed a hybrid multipath routing
protocol named MP-OLSR. It is based on the link state algorithm and employs
periodic exchange of messages to maintain topology information of the networks.
In the mean time, it updates the routing table in an on-demand scheme and
forwards the packets in multiple paths which have been determined at the
source. If a link failure is detected, the algorithm recovers the route
automatically. Concerning the instability of the wireless networks, the
redundancy coding is used to improve the delivery ratio. The simulation in NS2
shows that the new protocol can effectively improve the performance of the
networks
Fault localization in service-based systems hosted in mobile ad hoc networks
Fault localization in general refers to a technique for identifying
the likely root causes of failures observed in systems formed from
components. Fault localization in systems deployed on mobile ad hoc
networks (MANETs) is a particularly challenging task because those
systems are subject to a wider variety and higher incidence of faults
than those deployed in fixed networks, the resources available to
track fault symptoms are severely limited, and many of the sources of
faults in MANETs are by their nature transient.
We present a suite of three methods, each responsible for part of the
overall task of localizing the faults occurring in service-based
systems hosted on MANETs. First, we describe a dependence discovery
method, designed specifically for this environment, yielding dynamic
snapshots of dependence relationships discovered through decentralized
observations of service interactions. Next, we present a method for
localizing the faults occurring in service-based systems hosted on
MANETs. We employ both Bayesian and timing-based reasoning techniques
to analyze the dependence data produced by the dependence discovery
method in the context of a specific fault propagation model, deriving
a ranked list of candidate fault locations. In the third method, we
present an epidemic protocol designed for transferring the dependence
and symptom data between nodes of MANET networks with low
connectivity. The protocol creates network wide synchronization
overlay and transfers the data over intermediate nodes in periodic
synchronization cycles.
We introduce a new tool for simulation of service-based systems hosted
on MANETs and use the tool for evaluation of several operational
aspects of the methods. Next, we present implementation of the methods
in Java EE and use emulation environment to evaluate the methods. We
present the results of an extensive set of experiments exploring a
wide range of operational conditions to evaluate the accuracy and
performance of our methods.Open Acces
Fault Tolerant Wireless Sensor MAC Protocol for Efficient Collision Avoidance
In sensor networks communication by broadcast methods involves many hazards,
especially collision. Several MAC layer protocols have been proposed to resolve
the problem of collision namely ARBP, where the best achieved success rate is
90%. We hereby propose a MAC protocol which achieves a greater success rate
(Success rate is defined as the percentage of delivered packets at the source
reaching the destination successfully) by reducing the number of collisions,
but by trading off the average propagation delay of transmission. Our proposed
protocols are also shown to be more energy efficient in terms of energy
dissipation per message delivery, compared to the currently existing protocol.Comment: 14 page
A survey of self organisation in future cellular networks
This article surveys the literature over the period of the last decade on the emerging field of self organisation as applied to wireless cellular communication networks. Self organisation has been extensively studied and applied in adhoc networks, wireless sensor networks and autonomic computer networks; however in the context of wireless cellular networks, this is the first attempt to put in perspective the various efforts in form of a tutorial/survey. We provide a comprehensive survey of the existing literature, projects and standards in self organising cellular networks. Additionally, we also aim to present a clear understanding of this active research area, identifying a clear taxonomy and guidelines for design of self organising mechanisms. We compare strength and weakness of existing solutions and highlight the key research areas for further development. This paper serves as a guide and a starting point for anyone willing to delve into research on self organisation in wireless cellular communication networks
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