Implementation Of New Fault Tolerance Solution In Wireless Sensor Networks In A Multi-Channel Context
ABSTRACT
Wireless sensor network is application specific, which is deployed in an interested area like about
hundred or thousands of sensor nodes. All the sensor nodes communicate via a wireless medium
and works cooperatively to sense the environment in order to achieve the required task. Such sensor
nodes which is application specific needs a good fault tolerance scheme to keep the system
working. Since this sensor nodes are battery operated, have a small memory, deployed in harsh
environmental condition and can easily be depleted. So we improved on distributed fault tolerance
algorithm which enable the detection status of a node with fewer neighbors to be accurate and can
also detect the status of a node in a multi-channel context. Our distributed fault tolerance algorithm
uses majority voting with priority. Although in literature fault tolerance detection in multi-channel
channel context has not really been put into practice.
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TABLE OF CONTENTS
ABSTRACT ………………………………………………………………………………………………………………….. I
ACKNOWLEDGEMENT ………………………………………………………………………………………………. II
DEDICATION ………………………………………………………………………………………………………………. III
1 INTRODUCTION
1.1 Introduction ………………………………………………………………………………………………………….. 1
1.2 Problem Statement …………………………………………………………………………………………………. 3
1.3 Objective ……………………………………………………………………………………………………………… 4
1.4 Motivation of Work ………………………………………………………………………………………………. 4
1.5 Significance of Study ……………………………………………………………………………………………. 4
1.6 Thesis Organization ………………………………………………………………………………………………. 5
2 STATE OF ART
2.1 State of Art of Multi-channel Communication in WSNs ……………………………………………. 6
2.2 Discussion of Fault-Tolerance in WSNs …………………………………………………………………. 7
2.3 Fault Types …………………………………………………………………………………………………………. 7
2.4 Fault-Tolerance Occurrence at Different Level
2.4.1 Hardware Level …………………………………………………………………………………………… 8
2.4.2 Software Level ……………………………………………………………………………………………. 8
2.4.3 Application Level ……………………………………………………………………………………….. 8
2.4.4 Network Communication Level …………………………………………………………………… 9
2.5 Classification of Fault-Tolerance Techniques ……………………………………………………………. 9
2.6 Fault Detection Approaches in WSN ……………………………………………………………………….. 9
Centralized Detection Approach …………………………………………………………………………….. 9
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Decentralized or Distributed Approach …………………………………………………………………… 10
2.7 State of Art of Fault-Tolerance in WSN ……………………………………………………………………….. 11
3.0 Improved Distributed Fault-Tolerance Algorithm
3.1 Network Model …………………………………………………………………………………………………… 14
3.2 Fault Model ……………………………………………………………………………………………………….. 15
3.3 Existing Distributed Fault-Tolerance Detection Algorithm ………………………………………. 16
3.4 Improved Distributed Fault-Tolerance Detection Algorithm …………………………………….. 17
3.4.1 Algorithm By Peng Jiang ……………………………………………………………………………. 18
3.4.2 Step By Step Improved Algorithm ………………………………………………………………. 19
3.5 Discussion of Improved Algorithm …………………………………………………………………….. 20
4.0 Simulation or Proofs of The Proposed Algorithm
4.1 Theorems and Proofs of the Improved Distributed Algorithm ………………………………… 22
4.2 Analysis of The Fault-Tolerance Algorithm ………………………………………………………….. 24
4.3 Simulation With Omnetpp4.2 and Castalia 3.2 ……………………………………………………… 25
4.4 Simulation Result ……………………………………………………………………………………………… 26
5.0 Recommendation and Conclusion
5.1 Resolved Issue ………………………………………………………………………………………………….. 29
5.2 Unresolved Issue ………………………………………………………………………………………………. 29
5.3 Conclusion ………………………………………………………………………………………………………. 29
5.4 Challenges ………………………………………………………………………………………………………. 30
5.5 Future Work ……………………………………………………………………………………………………. 30
References …………………………………………………………………………………………………………………. 31
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CHAPTER ONE
1.0 INTRODUCTION
1.1 Introduction
Wireless sensor network consists of a number of sensor nodes and a base station (BS). A wireless
sensor network is a collection of nodes organised into a cooperative networks [1], Sensors contain
an on-board processor, perform simple computations within itself by using their processing
capabilities to process their raw data before transmitting it to the central node sent to the BS.
Wireless sensor nodes are low power, battery operated devices with limited computation and
transmission ability [2].
Sensor node deployment in wireless sensor network architecture is shown in fig 1 and the
component of sensor node its self is shown in fig 2.
Figure 1.1 Wireless sensor network Architecture
Figure 1.2: component of a sensor node
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In wireless sensor network (WSN) communication using the multi-hop mode where each node
communicate with the base station using an intermediate node, thus the node closer to the base
station of course become the only source through which all other node send their data to the base
station which give rise to interference and low throughput since all other node compete to use node
closer to the base station.
The WSN technology tremendous improvement has gained application in so many areas of our
daily routine such as medical care, environmental monitoring, smart buildings, banks,
telecommunication industry, many other industry and military application. Most of these sensor
application are in harsh environment which can cause WSNs to be prone to failure as compared to
other wireless networks, this involve safe mobility and performance, data quality and energy
consumption. Data quality is defined as the number of readings received by the user divided by total
number of readings generated by the network during an observation period [3]. To preserve resource
and achieve high quality of data, we identify the following as key requirements for FT in WSNs [3]:
1. Awareness of the network main operation and the status of the network resources.
2. Adaptability to the frequent changes in WSNs conditions.
The Physical harsh environmental condition that can affect WSNs deployment are fire, rain,
humidity, floods and any other physical thing that can affect it. All these can actually cause the
sensor nodes to fail or transmit error messages. To guarantee the network quality of service and
performance, it is essential for the wireless sensor networks to be able to detect faults, and to
perform something akin to healing and recovering from events that might cause faults in the
network, hence fault tolerance should be seriously considered in many wireless sensor network
deployments [7].
Fault tolerance is the mechanism put in place for sensor nodes to keep working after a failure
occurred. fault tolerance is a need in this type of networks due to sensor node characteristics, radio
communications and hostile environments in which these networks are deployed [4]. To successful
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utilize full deployment of WSNs, fault tolerance should be put in place. One approach to achieve
fault tolerance in wireless sensor networks is to deploy a small number of additional relay nodes to
provide k (k ≥ 1) vertex-disjoint paths between every pair of functioning devices (including sensors,
data sinks, and other wireless equipments, all termed target nodes in this paper) so that the network
can survive the failure of fewer than k nodes [6].
1.2 Problem Statement
Most of the implementation of wireless sensor networks are done in environment with harsh
conditions and as such the batteries of the sensor nodes prove very difficult to charge or replace
immediately when the batteries run off. The mode of communication in WSN include single-hop
and multi-hop. In multi-hop wireless sensor networks bandwidth is a critical issue, because of
interference between successive hops on the same path as well as that between neighbouring paths
[5]. Hence in order to solve this problem of interference and maximize throughput and also to
overcome fault thus several fault tolerance scheme are been diverse. Using a single channel for
communication causes a heavy work load on it and many packets do not get to their destination due
to collision, so when a node fail the entire network stop functioning. Due to this disadvantage a
CSMA/CA or CD are been used to enable parallel communication but because of the heavy work
load, this solution do not provide high channel utilization. Another cost effective solution is to use
multiple channels that works for parallel data transmission based on the current WSN hardware,
such as MICAz and Telos that provide multiple channels with single radio [5]. Thus in WSNs, there
are issue of node failure and transmission failure which are the two main fault in Wireless sensor
networks.
Fault is one of the major impact in building a Sensor networks, the ability to identify node fault in
sensor network deployment is one of the major issue. Retransmission problem for the detected
faulty node also account for in WSNs deployment. A faulty sensor node can send incorrect message
to the base station. Imagine in military deployment of sensor nodes where sensors are expected to
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detect the enemy, if such sensor failed then the whole military are in serious danger.
1.3 Objectives
The main objective of these thesis is to provide an adequate solution to fault tolerance in wireless
sensor networks in a multi-channel context. The general objectives are:
1. To carry out state of the art of multi-channel communication and fault tolerance in wireless
sensor networks
2. To implement a proposed algorithm for decentralized fault tolerance detection in wireless
sensor network.
3. To Simulate the implemented algorithm
4. To compare implemented algorithm with already existing algorithm
1.4 Motivation of work
From our research and findings we discovered that most of the papers in literature never care about
fault tolerance in multi-channel context. Their algorithm never put into consideration sensor nodes
with all faulty neighbors. Some of these papers just focus on finding faulty nodes without applying
the algorithm in a gradual process. That means making sure that nodes with fewer neighbors are
treated last and nodes with large neighbors are treated first. Doing this ensure that sensor nodes are
not mis-diagnose.
1.5 Significance of Study
There are several methods in literature for solving the problem of node failure in wireless sensor
network deployment. Our improved distributed fault tolerance algorithm will enable the researchers
and wireless sensor network application deployment to be able to detect node failure as fast as
possible and at the same time use an alternative channel in transmitting data to the base station
using the one hop neighbors.
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1.6 Thesis Organization
The remaining part of these thesis is organised as follows, chapter two gives state of the art of
multi-channel communication and fault tolerance in WSNs, chapter three gives the materials and
methods of the thesis, chapter four gives the implementation of the algorithm and simulation and
comparison with existing work and chapter five gives conclusion and future work.
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