Ensuring connectivity in Wireless Sensor Networks (WSN) is a challenging issue, especially in hazardous
areas (like battlefield). Many applications of WSN require an important level of connectivity in the network
to detect a given event (like detection Intrusion) and forward it to the ”sink” node in order to alert users.
For these risky areas the deterministic deployment is not usually guaranteed and the network is composed
by a set of disconnected Islands. We present in our work two strategies to relocate sensors in order to
improve the connectivity using mobile Robots. These two solutions are called Multi-Robot Island-based
Relocation (MRIBR) and Multi-Robot Grid-Based Island-based Relocation (MRGIR). Through several
simulations, we show that MRGIR outperforms MRIBR. Our study can be used especially to make a tradeoff
between the number of deployed sensors and the numbers of the used mobile robots, according to the
quality needed for the application.
This document discusses approaches to improve reliability in wireless sensor networks. It proposes a dynamic sectoring scheme where the network area is divided into sectors with a sensor node assigned as sector head for each. When an event occurs, only that sector is activated, reducing congestion and energy use. This is expected to enhance packet delivery ratio and reduce losses. Prior work on using data fusion and opportunistic flooding algorithms to improve reliability is also reviewed. The dynamic sectoring approach aims to reliably transmit data with low congestion and energy usage.
Wireless Sensor Network (WSN) consists of sensor nodes which interact with each other through physical parameters like sunlight, wind, vibration, humidity etc. Routing protocols provide an optimal data transmission route from sensor nodes to sink node to save energy of nodes. From Base Station (BS) Sensor node sends and receives data to or from wireless stations. Clustering mechanism is one of the popular routing mechanisms used in WSN for optimizing the problem in sensor nodes. There are two types of clustering schemes known as homogeneous schemes and heterogeneous schemes. In Homogeneous scheme initial energy is same for each node but in heterogeneous scheme initial energy is different for each node and also used to determine the efficiency of sensor networks. Enhanced Modified LEACH (EMODLEACH) is a reactive protocol which is implemented for homogeneous network model. We have implemented the concept of Efficient Cluster head Replacement scheme and Dual transmitting power level scheme of MODLEACH along with the concept of Efficient Intra Cluster transmission Scheme of TEEN in LEACH. We analyze the PEGASIS protocol and modified the exiting protocol called improved energy balanced routing protocol (IEBRP).This IEBRP is based on cluster formation, cluster routing and other aspects of LEACH protocol.
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Monthly Journal,
Good quality Journals,
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This document summarizes a survey on wireless sensor network lifetime constraints. It discusses how sensor node energy consumption affects network lifetime and the role of routing protocols in extending lifespan. Generic energy consumption includes reception, transmission, and sensing. Deployment strategies like deterministic grids can balance energy usage to prolong network lifetime. Routing protocols aim to minimize transmissions and optimize paths to reduce energy costs.
A MULTI-PATH ROUTING DETERMINATION METHOD FOR IMPROVING THE ENERGY EFFICIENCY...
A selective forwarding attack in mobile wireless sensor networks is an attack that selectively drops or delivers event packets as the compromised node moves. In such an attack, it is difficult to detect the compromised node compared with the selective forwarding attack occurring in the wireless sensor network
because all sensor nodes move. In order to detect selective forwarding attacks in mobile wireless sensor networks, a fog computing-based system for a selective forwarding detection scheme has been proposed. However, since the proposed detection scheme uses a single path, the energy consumption of the sensor node for route discovery when the sensor node moves is large. To solve this problem, this paper uses fuzzy
logic to determine the number of multi-paths needed to improve the energy efficiency of sensor networks. Experimental results show that the energy efficiency of the sensor network is improved by 9.5737% compared with that of the existing scheme after 200 seconds when using the proposed scheme
The document summarizes localization techniques for wireless sensor nodes. It discusses several common localization methods including known location-based using GPS, proximity-based using signal strength, angle-based using angle of arrival, and range-based using time of arrival or time difference of arrival. It also covers some challenges with each approach like accuracy limitations and environmental factors. Finally, it provides a brief comparison of the localization techniques and their typical accuracy ranges from 1-15 meters depending on the method.
Single Sink Repositioning Technique in Wireless Sensor Networks for Network L...
This document presents a technique called single sink repositioning to extend the lifetime of wireless sensor networks. Sensor nodes have limited battery power, so energy consumption must be managed carefully. In typical static sink networks, nodes farther from the sink expend more energy transmitting data and drain their batteries quicker, shortening network lifetime. The proposed approach tracks the distance of each node to the sink and calculates an optimal sink position to minimize distances. It simulates moving the sink to this position using an algorithm in NS-2. Simulation results show repositioning the sink achieves significant energy savings compared to static sinks, helping improve overall network lifetime.
Maximizing network topology lifetime using mobile node rotation
NS2 Projects for M. Tech, NS2 Projects in Vijayanagar, NS2 Projects in Bangalore, M. Tech Projects in Vijayanagar, M. Tech Projects in Bangalore, NS2 IEEE projects in Bangalore, IEEE 2015 NS2 Projects, WSN and MANET Projects, WSN and MANET Projects in Bangalore, WSN and MANET Projects in Vijayangar
IRJET- Studies on Lifetime Enhancement Techniques for Wireless Sensor NetworkIRJET Journal
1) Wireless sensor networks consist of small autonomous sensor nodes that monitor environmental conditions and communicate wirelessly. Battery power is limited so increasing node lifetime is important.
2) Techniques to enhance lifetime include clustering nodes so cluster heads can aggregate data and reduce transmissions, relocating the data sink to balance energy usage, and using energy-efficient routing protocols.
3) Neural networks can also be used to help manage the fuzzy nature of wireless sensor networks and account for various factors that influence node operations.
Energy Efficient Data Transmission through Relay Nodes in Wireless Sensor Net...IDES Editor
In a Wireless Sensor Network (WSN) having a single
sink, information is given to the distant nodes from beacons
by overhearing. Since it is out of the communication range,
information is not sent directly to the static sink (SS). If a
distant node is not able to communicate directly, then it should
send its own packet to another node which is closer to the
Base Station (BS) so that the received packets are relayed to
the BS by this node. In this paper, we propose a relay node
selection algorithm to reduce contention and improve energy
efficiency. In this algorithm, each data packet of direct
communication should include the received signal strength
(RSS) of the beacon packet. The distant node selects a node
with the maximum RSS value as a relay. The algorithm also
assigns transmitting intervals to each relay node. By our
simulation results, we show that our proposed algorithm
improves the packet delivery ratio and energy efficiency.
COMPRESSIVE DATA GATHERING TECHNIQUE BY AVOIDING CORRELATED DATA IN WSNpharmaindexing
This document proposes a technique for compressive data gathering in wireless sensor networks using mobile data collectors. It involves identifying correlated sensor data within clusters near polling points and defining a tour plan for mobile collectors that avoids visiting these correlated sensors. This is done using a spatial correlation method. The goal is to identify new optimal polling points by avoiding correlated sensors, which reduces the tour length of mobile collectors and the number of polling points needed. This extends the lifetime of the wireless sensor network. The document provides background on related work using mobile data collectors and discusses how the proposed approach improves upon prior methods.
This document discusses approaches to improve reliability in wireless sensor networks. It proposes a dynamic sectoring scheme where the network area is divided into sectors with a sensor node assigned as sector head for each. When an event occurs, only that sector is activated, reducing congestion and energy use. This is expected to enhance packet delivery ratio and reduce losses. Prior work on using data fusion and opportunistic flooding algorithms to improve reliability is also reviewed. The dynamic sectoring approach aims to reliably transmit data with low congestion and energy usage.
Wireless Sensor Network (WSN) consists of sensor nodes which interact with each other through physical parameters like sunlight, wind, vibration, humidity etc. Routing protocols provide an optimal data transmission route from sensor nodes to sink node to save energy of nodes. From Base Station (BS) Sensor node sends and receives data to or from wireless stations. Clustering mechanism is one of the popular routing mechanisms used in WSN for optimizing the problem in sensor nodes. There are two types of clustering schemes known as homogeneous schemes and heterogeneous schemes. In Homogeneous scheme initial energy is same for each node but in heterogeneous scheme initial energy is different for each node and also used to determine the efficiency of sensor networks. Enhanced Modified LEACH (EMODLEACH) is a reactive protocol which is implemented for homogeneous network model. We have implemented the concept of Efficient Cluster head Replacement scheme and Dual transmitting power level scheme of MODLEACH along with the concept of Efficient Intra Cluster transmission Scheme of TEEN in LEACH. We analyze the PEGASIS protocol and modified the exiting protocol called improved energy balanced routing protocol (IEBRP).This IEBRP is based on cluster formation, cluster routing and other aspects of LEACH protocol.
ER Publication,
IJETR, IJMCTR,
Journals,
International Journals,
High Impact Journals,
Monthly Journal,
Good quality Journals,
Research,
Research Papers,
Research Article,
Free Journals, Open access Journals,
erpublication.org,
Engineering Journal,
Science Journals,
This document summarizes a survey on wireless sensor network lifetime constraints. It discusses how sensor node energy consumption affects network lifetime and the role of routing protocols in extending lifespan. Generic energy consumption includes reception, transmission, and sensing. Deployment strategies like deterministic grids can balance energy usage to prolong network lifetime. Routing protocols aim to minimize transmissions and optimize paths to reduce energy costs.
A MULTI-PATH ROUTING DETERMINATION METHOD FOR IMPROVING THE ENERGY EFFICIENCY...ijwmn
A selective forwarding attack in mobile wireless sensor networks is an attack that selectively drops or delivers event packets as the compromised node moves. In such an attack, it is difficult to detect the compromised node compared with the selective forwarding attack occurring in the wireless sensor network
because all sensor nodes move. In order to detect selective forwarding attacks in mobile wireless sensor networks, a fog computing-based system for a selective forwarding detection scheme has been proposed. However, since the proposed detection scheme uses a single path, the energy consumption of the sensor node for route discovery when the sensor node moves is large. To solve this problem, this paper uses fuzzy
logic to determine the number of multi-paths needed to improve the energy efficiency of sensor networks. Experimental results show that the energy efficiency of the sensor network is improved by 9.5737% compared with that of the existing scheme after 200 seconds when using the proposed scheme
A Survey on Localization of Wireless SensorsKarthik Mohan
The document summarizes localization techniques for wireless sensor nodes. It discusses several common localization methods including known location-based using GPS, proximity-based using signal strength, angle-based using angle of arrival, and range-based using time of arrival or time difference of arrival. It also covers some challenges with each approach like accuracy limitations and environmental factors. Finally, it provides a brief comparison of the localization techniques and their typical accuracy ranges from 1-15 meters depending on the method.
Single Sink Repositioning Technique in Wireless Sensor Networks for Network L...IRJET Journal
This document presents a technique called single sink repositioning to extend the lifetime of wireless sensor networks. Sensor nodes have limited battery power, so energy consumption must be managed carefully. In typical static sink networks, nodes farther from the sink expend more energy transmitting data and drain their batteries quicker, shortening network lifetime. The proposed approach tracks the distance of each node to the sink and calculates an optimal sink position to minimize distances. It simulates moving the sink to this position using an algorithm in NS-2. Simulation results show repositioning the sink achieves significant energy savings compared to static sinks, helping improve overall network lifetime.
NS2 Projects for M. Tech, NS2 Projects in Vijayanagar, NS2 Projects in Bangalore, M. Tech Projects in Vijayanagar, M. Tech Projects in Bangalore, NS2 IEEE projects in Bangalore, IEEE 2015 NS2 Projects, WSN and MANET Projects, WSN and MANET Projects in Bangalore, WSN and MANET Projects in Vijayangar
Toward accurate mobile sensor network localization in noisy environmentsJPINFOTECH JAYAPRAKASH
The document proposes a fuzzy logic-based approach for mobile node localization in challenging indoor and mobile environments characterized by high radio signal irregularity. It develops a fuzzy multilateration module and fuzzy inference module to obtain a node's location from noisy RSS measurements. Extensive simulation results show improvements in localization accuracy from 20 to 40 percent when radio irregularity is high, outperforming state-of-the-art solutions. A hardware implementation on motes transported by robots confirms the simulation results in real-world testing.
Indoor Localization Using Local Node Density In Ad Hoc WSNsjoaquin_gonzalez
Presentation for Master Thesis "Indoor Localization Using Local Node Density In Ad Hoc WSNs", research supported by Free University Berlin. Coordinators: Freddy Lopez Villafuerte, Gianluca Cornetta.
This document proposes an energy efficient framework for data collection in wireless sensor networks using prediction. The framework uses clustering, where sensor nodes are organized into clusters with a cluster head. The cluster head can enable or disable local prediction at sensor nodes to reduce data transmission. When prediction is enabled, sensors only transmit data if the value differs from the predicted value by more than a threshold. Sensors can also sleep when not transmitting to save energy. The document evaluates the performance of this framework through simulations, finding it reduces energy consumption compared to alternatives by integrating prediction with sleep/awake cycles.
A review of Hierarchical energy Protocols in Wireless Sensor Networkiosrjce
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
An Adaptive Energy Efficient Reliable Routing Protocol for Wireless Sensor Ne...IDES Editor
A reliable routing protocol for wireless sensor
networks (WSN) should be capable of adjusting to
constantly varying network conditions while conserving
maximum power. Existing Routing protocols provide
reliability at the cost of high energy consumption. In this
paper, we propose to develop an Adaptive Energy Efficient
Reliable Routing Protocol (AEERRP) with the aim of
keeping the energy consumption low while achieving high
reliability. In our proposed protocol, the data forwarding
probability is adaptively adjusted based on the measured
loss conditions at the sink. So only for high loss rates, a node
makes use of high transmission power to arrive at the sink.
Whenever the loss rate is low, it adaptively lessens the
transmission power. Since the source rebroadcasts the data,
until the packet loss is minimized, high data reliability is
achieved. By simulation results we show that the proposed
protocol achieves high reliability while ensuring low energy
consumption and overhead.
Energy-Balanced Dispatch of Mobile Sensors in a Hybrid Wireless Sensor Networkambitlick
The document discusses energy-efficient dispatch of mobile sensors in a hybrid wireless sensor network. It formulates the problem as a multiround sensor dispatch problem to schedule mobile sensors' traveling paths in an energy-balanced way, maximizing system lifetime. It proves the problem is NP-complete. It then proposes a centralized heuristic that minimizes mobile sensors' moving energy while balancing energy consumption, and a distributed heuristic that utilizes a grid structure for event locations to bid for mobile sensors. Simulations show the effectiveness of the proposed schemes at extending system lifetime.
REVIEW OVER HOLE HEALING TECHNIQUES IN WIRELESS SENSOR NETWORKS ijasuc
This document summarizes and compares various hole healing techniques in wireless sensor networks. It discusses hole selection methods such as random, maximum size, nearest distance, travelling salesman problem, and weighted. The weighted method considers hole angle, distance, and depth to assign priority. It then reviews hole healing processes including Voronoi diagram based, Delaunay's triangulation, and direction adjustment approaches. Experimental results show the weighted method improves both coverage and connectivity while the travelling salesman method achieves near complete coverage with additional nodes.
Comparative Review for Routing Protocols in Mobile Ad-Hoc Networksijasuc
Wireless Mobile Ad-Hoc Networks is one of the attractive research field that growing exponentially in the
last decade. it surrounded by much challenges that should be solved the improve establishment of such
networks. Failure of wireless link is considered as one of popular challenges faced by Mobile Ad-Hoc
Networks (MANETs). As this type of networks does not require any pre-exist hardware. As well as, every
node have the ability of roaming where it can be connected to other nodes dynamically. Therefore, the
network internal structure will be unpredictably changed frequently according to continuous activities
between nodes that simultaneously update network topology in the basis of active ad-hoc nature. This
model puts the functionality of routing operation in crucial angle in the area of research under mobile adhoc
network field due to highly dynamic nature. Adapting such kernel makes MANET indigence new
routing techniques to settle these challenges. Thereafter, tremendous amount of routing protocols proposed
to argue with ad-hoc nature. Thus, it is quite difficult to specify which protocols operate efficiently under
different mobile ad-hoc scenarios. This paper examines some of the prominent routing protocols that are
designed for mobile ad-hoc networks by describing their structures, operations, features and then
comparing their various characteristics.
COMMUNITY DETECTION USING INTER CONTACT TIME AND SOCIAL CHARACTERISTICS BASED...ijasuc
Delay Tolerant Networks (DTNs) where the node connectivity is opportunistic and end-to-end path between
any pair of source and destination is not guaranteed most of the time. Hence the messages are transferred
from source to destination via intermediate nodes on hop to hop basis using store-carry-forward paradigm.
Due to quick advancement in hand held devices such as smart phone and laptop with support of wireless
communication interface carried by human being, it is possible in coming days to use DTNs for message
dissemination without setting up infrastructure. The routing task becomes challenging in DTNs due to
intermittent network connectivity and the connection opportunity arises only when node comes in
transmission range of each other. The performance of the routing protocols depend on the selection of
appropriate relay node which can deliver the message to final destination in case of source and destination
do not meet at all. Many social characteristics are exhibited by the human being like friendship,
community, similarity and centrality which can be exploited by the routing protocol in order to take the
forwarding decisions. Literature shows that by using these characteristics, the performance of DTN routing
protocols have been improved in terms of delivery probability. The existing routing schemes used
community detection using aggregated contact duration and contact frequency which does not change over
the time period. We propose community detection through Inter Contact Time (ICT) between node pair
using power law distribution where the members of community are added and removed dynamically. We
also considered single copy of each message in entire network to reduce the network overhead. The
proposed routing protocol named Social Based Single Copy Routing (SBSCR) selects the suitable relay
node from the community members only based on the social metrics such as similarity and friendship
together. ICTs show power law nature in human mobility which is used to detect the community structure at
each node. A node maintains its own community and social metrics such as similarity and friendship with
other nodes. Whenever node has to select the relay node then it selects from its community with higher
value of social metric. The simulations are conducted using ONE simulator on the real traces of campus
and conference environments. SBSCR is compared with existing schemes and results show that it
outperforms in terms of delivery probability and delivery delay with comparable overhead ratio.
Modeling the Adaption Rule in Contextaware Systemsijasuc
Context awareness is increasingly gaining applicability in interactive ubiquitous mobile computing
systems. Each context-aware application has its own set of behaviors to react to context modifications. This
paper is concerned with the context modeling and the development methodology for context-aware systems.
We proposed a rule-based approach and use the adaption tree to model the adaption rule of context-aware
systems. We illustrate this idea in an arithmetic game application.
ORGANIC USER INTERFACES: FRAMEWORK, INTERACTION MODEL AND DESIGN GUIDELINESijasuc
The document proposes an organic user interface (OUI) framework and interaction model called SMaG (Speech Manipulation air-Gesture).
It divides the control module of the tangible user interface framework into tangible and intangible controls. Tangible controls involve direct contact like touch, while intangible controls include speech and gestures.
The paper then introduces the SMaG model, which categorizes OUI input techniques. Based on this model, the paper provides design guidelines for OUIs with principles for look, feel, and design. The guidelines consider the best and worst uses of each SMaG technique.
Introducing ENMAT V2 Beta
ENMAT (Energy Monitoring & Targeting) is a web based Energy Monitoring and Targeting system. It presents energy management data in a way that is relevant, meaningful and useful to users.
This document analyzes the impacts of various structural factors on energy consumption in cluster-based wireless sensor networks through extensive simulations. It finds that the best performance for prolonging network lifetime is achieved by locating a sufficient number of sinks around the network area rather than having a single sink located at the edge of the topology. The document discusses clustering approaches for wireless sensor networks and three models for electing cluster heads. It also outlines the experimental architecture and parameters used in the simulations.
Iterative network channel decoding with cooperative space-time transmissionijasuc
This document summarizes an iterative network-channel decoding scheme for cooperative space-time transmission with network coding. The scheme uses convolutional codes as network codes at the relay node and Reed-Solomon codes as channel codes at the user nodes. An iterative joint network-channel decoder exchanges soft information between convolutional code-based network decoder and Reed-Solomon code-based channel decoders. Extrinsic information transfer analysis is performed to investigate the convergence properties of the proposed iterative decoder.
Impact of the temperature and humidity variations on link quality of xm1000 m...ijasuc
The core motivations of deploying a sensor network for a specific application come from the autonomy of
sensors, their reduced size, and their capabilities for computing and communicating in a short range.
However, many challenges for sensor networks still exist: minimizing energy consumptions, and ensuring
the performance of communication that may be affected by many parameters. The work described in this
paper covers mainly the analysis of the impact of the temperature and humidity variations on link quality of
XM1000 operating under TinyOS. Two-way ANOVA test has been applied and the obtained results show
that both the temperature and humidity variations impact RSSI.
A W ARNING S YSTEM F OR O VERSPEED A T T HE C ORNER U SING V ISIBLE L...ijasuc
When a car enters a
corner
with
over speed,
it rise
s
the accident risk higher
.
To warn the risk and urging
the caution to drivers, many of the accident
-
prone corners have warning rights. The driver can decelerate
the car smoothly and pass through the
corner safety by those
devices.
However
, appropriate speed for each
corner is differ
ent by curvature of the corner and characteristics of the vehicle.
The driver
has
to suppose
the safe speed for every corner only by experience,
usually. Of
co
urse too much slow causes traffic jam.
Especially at the first road in the first place for the dr
iver, it is difficult to suppose the curvatures of the
corners. Then
, we propose a visible light communication system so that the warning lights in the corner
send appropriate warning information. V
isible light communication transmits
a signal by blinking the light.
One of the characteristics of
visible light communication is that it can use
existing
lighting equipment as a
transmitter.
In our system, we
can distribute the
warning
information to the driver using the visible light
commun
ication.
Though
the curvature(R:radious) of the corner does not change, the speed of each vehicle
to approach the corner always to different.
Focusing the distance from the corner to the car, we consider a
communication system to send different kind of inf
ormation according to that
distance.
If
the distance is
enough long, the driver has a plenty of time to decelerate the
vehicle. The
more the distance becomes short,
the more the driver is required rapid
deceleration. Therefore
, to distribute the appropriat
e warning
information to the driver, dividing the distance from the corner into some areas, we make the system to send
different information in each
area. Generally
in communication system, modulation primarily changes the
amplitude, phase or
frequency. In
visible light communication, change of the amplitude changes the
brightness, which causes flickering that burdens the
drivers. Therefore
we cannot use amplitude based
modulation.
Next
we consider the varying the
phase.
Unfortunately
, it is difficult for t
he receiver using
photodiode or phototransistor to read the difference of the phase of the signals, because the frequency of
the light is very high
in visible light communication.
Then we employ 'symbol length' with the Pulse
Position
Modulation (
PPM).In our method, brightness does not change when the symbol length is
changed.
We
investigate the system performance by changing the communication
speed. Short
symbol length in high
frequency is sensitive and vulnerable to noise, instead of low frequenc
y with strong against
noise.
Using
this characteristic of symbol length modulation, dif
Ambiences on the-fly usage of available resources through personal devicesijasuc
In smart spaces such as smart homes, computation is
embedded everywhere: in toys, appliances, or the
home’s infrastructure. Most of these devices provid
e a pool of available resources which the user can
take
advantage, interacting and creating a friendly envi
ronment. The inherent composability of these system
s
and other unique characteristics such as low-cost e
nergy, simplicity in module programming, and even
their small size, make them a suitable candidate fo
r dynamic and adaptive ambient systems. This resear
ch
work focuses on what is defined as an “ambience”, a
space with a user-defined set of computational
devices. A smart-home is modeled as a collection of
ambiences, where every ambience is capable of
providing a pool of available resources to the user
. In turn, the user is supposed to carry one or sev
eral
personal devices able to interact with the ambience
s, taking advantage of his inherent mobility. In th
is way,
the whole system can benefit from resources discove
red in the spatial proximity. A software architectu
re is
designed, which is based on the implementation of l
ow-cost algorithms able to detect and update the sy
stem
when changes in an ambience occur. Ambience middlew
are implementation works in a wide range of
architectures and OSs, while showing a negligible o
verhead in the time to perform the basic output
operations.
Spatial Correlation Based Medium Access Control Protocol Using DSR & AODV Rou...IOSR Journals
The document summarizes a proposed spatial correlation-based medium access control protocol for wireless sensor networks that aims to improve energy efficiency. It discusses how sensor nodes are spatially distributed and correlated in detecting events. An iterative node selection algorithm is used to select a minimum set of representative sensor nodes based on a distortion constraint, in order to reduce redundant transmissions. The protocol uses vector quantization to calculate distances between nodes and a mobile element. It then evaluates the performance of using the DSR and AODV routing protocols with this spatial correlation-based MAC protocol in terms of energy consumption and packet drop ratio through simulations. The simulation results show that the protocol with AODV routing performs better than with DSR routing.
The document discusses implementing a smart antenna system in mobile ad hoc networks to improve throughput and bit error rate. A smart antenna system uses an array of antennas and digital signal processing to direct transmissions toward desired nodes, allowing for increased network capacity over omnidirectional antennas. The document reviews mobile ad hoc networks, smart antenna systems, and how using smart antennas in an ad hoc network can enhance performance metrics like throughput and bit error rate.
A NOVEL APPROACH TO DETECT THE MOVEMENT OF TARGET IN WIRELESS SENSOR NETWORKSEditor IJMTER
The document summarizes a novel approach to detect target movement in wireless sensor networks. It proposes a prediction-based target tracking and sleep scheduling protocol (PPSS) to improve energy efficiency. The protocol reduces actively awakened nodes and controls their active time. It uses a related neighborhood graph to divide the area into non-overlapping faces for target tracking. An edge detection algorithm identifies polygon locations and wakes nodes before a target crosses to continuously monitor mobile targets. The approach achieves high tracking accuracy while reducing energy costs in wireless sensor networks.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
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IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Optimum Sensor Node Localization in Wireless Sensor Networkspaperpublications3
Abstract: Scientists, engineers, and researchers use wireless sensor networks (WSN) for a wide array of applications. Many of these applications rely on knowledge of the precise position of each node. An optimum localization algorithm can be used for determining the position of nodes in a wireless sensor network. This paper provides an overview of different approach of node localization discovery in wireless sensor networks. The overview of the schemes proposed by different scholars for the improvement of localization in wireless sensor networks is also presented. Experiments were performed in a testbed area containing anchor and blind nodes deployed in it to characterize the pathloss exponent and to determine the localization error of the algorithm. Details regarding the implementation of new algorithm are also discussed in this paper.
Underwater localization and node mobility estimationIJECEIAES
In this paper, localizing a moving node in the context of underwater wireless sensor networks (UWSNs) is considered. Most existing algorithms have had designed to work with a static node in the networks. However, in practical case, the node is dynamic due to relative motion between the transmitter and receiver. The main idea is to record the time of arrival message (ToA) stamp and estimating the drift in the sampling frequency accordingly. It should be emphasized that, the channel conditions such as multipath and delay spread, and ambient noise is considered to make the system pragmatic. A joint prediction of the node mobility and speed are estimated based on the sampling frequency offset estimation. This sampling frequency offset drift is detected based on correlating an anticipated window in the orthogonal frequency division multiplexing (OFDM) of the received packet. The range and the distance of the mobile node is predicted from estimating the speed at the received packet and reused in the position estimation algorithm. The underwater acoustic channel is considered in this paper with 8 paths and maximum delay spread of 48 ms to simulate a pragmatic case. The performance is evaluated by adopting different nodes speeds in the simulation in two scenarios of expansion and compression. The results show that the proposed algorithm has a stable profile in the presence of severe channel conditions. Also, the result shows that the maximum speed that can be adopted in this algorithm is 9 km/h and the expansion case profile is more stable than the compression scenario. In addition, a comparison with a dynamic triangular algorithm (DTN) is presented in order to evaluate the proposed system.
Redundant Actor Based Multi-Hole Healing System for Mobile Sensor NetworksEditor IJCATR
In recent years, the Mobile Wireless Sensor Network
is the emerging solution for monitoring of a specified region of
interest. Several anomalies can occur in WSNs that impair their
desired functionalities resulting in the formation of different
kinds of holes, namely: coverage holes, routing holes. Our
ultimate aim is to cover total area without coverage hole in
wireless sensor networks. We propose a comprehensive solution,
called holes detection and healing. We divided our proposed
work into two phases. The first phase consists of three sub- tasks;
Hole-identification, Hole-discovery and border detection. The
second phase treats the Hole-healing with novel concept, hole
healing area. It consists of two sub-tasks; Hole healing area
determination and node relocation.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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Wireless sensor networks consist of hundreds or thousands of sensor nodes that are distributed to monitor various environmental conditions through sensing, processing, and communicating with each other and a base station. These sensor nodes have limitations in terms of power, memory, and processing capabilities compared to other networks. Wireless sensor networks have a wide range of applications including military surveillance, environmental monitoring, smart homes/buildings, and healthcare.
11.0005www.iiste.org call for paper.a robust frame of wsn utilizing localizat...Alexander Decker
This document discusses localization techniques for wireless sensor networks. It begins by defining localization as identifying a sensor node's position and explains how accuracy is important. It then describes two main categories of localization techniques: range-based and range-free. Range-based uses distance or angle measurements between nodes for higher accuracy but requires expensive hardware. Range-free relies on information from nearby nodes and is less accurate but cheaper. The document reviews several specific localization algorithms from previous research and their limitations. It concludes by stating that energy efficiency is critical for wireless sensor networks due to limited battery life.
5.a robust frame of wsn utilizing localization technique 36-46Alexander Decker
This document discusses localization techniques for wireless sensor networks. It begins by defining localization as identifying a sensor node's position and explains that localization is a fundamental challenge for wireless sensor networks. It then describes two main categories of localization techniques: range-based and range-free. Range-based techniques use distance or angle measurements between nodes to determine positions but require expensive hardware. Range-free techniques estimate positions based on neighboring node information and are less expensive but less accurate. The document reviews several specific localization algorithms from previous research and discusses their advantages and limitations.
1) The document discusses implementing mobile target detection in wireless sensor networks. It focuses on using techniques like Tabu Search heuristics and Sequential Probability Ratio Tests to detect mobile targets and replicas.
2) A key challenge discussed is detecting when a mobile node has been replicated, which the proposed approach attempts to do using SPRT to analyze node speeds and determine if two nodes with the same identity are present.
3) The paper also examines using game theory approaches to maximize network lifetime and weighted intrusion detection in wireless sensor networks for mobile target detection. Experimental results show the SPRT-based replica detection works rapidly with no false positives or negatives.
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This document reviews the use of ant colony optimization algorithms for wireless sensor networks. It begins with background on wireless sensor networks and important concepts like sensor nodes, clusters, cluster heads, and base stations. It then discusses routing protocols for wireless sensor networks including location-based, data-centric, mobility-based, and multipath-based protocols. The document provides an overview of ant colony optimization algorithms and reviews several related works that have applied these algorithms to problems in wireless sensor networks, such as sensor wakeup control and increasing network lifetime. It concludes by discussing techniques like data mining and ant colony optimization that could be used to improve wireless sensor network performance.
Ant Colony Optimization for Wireless Sensor Network: A Reviewiosrjce
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document discusses improving the performance of mobile wireless sensor networks using a modified DBSCAN clustering algorithm. It first provides background on wireless sensor networks and discusses challenges related to mobility. It then reviews several existing works related to clustering, mobility, and extending network lifetime. The paper proposes using a modified DBSCAN algorithm that takes into account mobility, remaining energy, and distance to base station to select cluster heads. It evaluates the performance of this approach based on throughput, delay, and packet delivery ratio, finding improvements over other methods.
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This document reviews and summarizes reactive and proactive wireless sensor network protocols. It begins with an abstract discussing the importance of energy utilization in wireless sensor networks (WSNs) due to resource-constrained battery-powered sensor nodes. The document then provides background on WSNs, describing their origin, characteristics, and applications. It discusses routing protocols for WSNs, categorizing them as proactive (table-driven) or reactive (on-demand). Specific protocols discussed include Low Energy Adaptive Clustering Hierarchy (LEACH) and Stable Cluster Head Election (SCHE) Protocol, which are cluster-based routing protocols aimed at improving energy efficiency and extending network lifetime.
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Multi-Robot Sensor Relocation to Enhance Connectivity in a WSN
1. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
DOI : 10.5121/ijasuc.2016.7201 1
MULTI-ROBOT SENSOR RELOCATION TO
ENHANCE CONNECTIVITY IN A WSN
Sahla Masmoudi Mnif and Leila Azouz Saidane
National School of Computer Science, University of Manouba, Manouba, Tunisia
ABSTRACT
Ensuring connectivity in Wireless Sensor Networks (WSN) is a challenging issue, especially in hazardous
areas (like battlefield). Many applications of WSN require an important level of connectivity in the network
to detect a given event (like detection Intrusion) and forward it to the ”sink” node in order to alert users.
For these risky areas the deterministic deployment is not usually guaranteed and the network is composed
by a set of disconnected Islands. We present in our work two strategies to relocate sensors in order to
improve the connectivity using mobile Robots. These two solutions are called Multi-Robot Island-based
Relocation (MRIBR) and Multi-Robot Grid-Based Island-based Relocation (MRGIR). Through several
simulations, we show that MRGIR outperforms MRIBR. Our study can be used especially to make a trade-
off between the number of deployed sensors and the numbers of the used mobile robots, according to the
quality needed for the application.
KEYWORDS
Sensor, Wireless Sensor Network, Mobile Robot, Redundant, Connectivity, Relocation
1. INTRODUCTION
Wireless Sensor Network (WSN) applications have been suggested for many applications,
especially in risky and hazardous regions. The main objective of these applications is to detect
any abnormal event in the area of interest. One relevant application is detection intrusion in a
battlefield and coast and border surveillance. We remind that a WSN is composed of a set of
small entities called “sensors,” each sensor is characterized by a limited energy and is constrained
in its computation and communication resources. When a sensor detects a phenomenon, in the
given area, the deployed sensors have to communicate together in order to forward this event to
the “sink” node. The sink node will alert the user by the detected event. An illustrative
application is military applications especially for detection intrusion in battlefield or frontier
control. The deployment in these risky areas cannot be assisted by human, and a random
deployment is necessary. Random initial deployment leads in most of cases, to a portioned
network. In each network partition redundant nodes can appear. However the connectivity must
be usually guaranteed to survey correctly the controlled zone. We propose to use mobile robots to
enhance the connectivity in the network using redundant nodes. The main role of the mobile
robots is to discover the network topology and to connect the disconnected parts of the network
simultaneously. In addition, robots must coordinate their movement and cooperate during
operation.
2. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
2
We propose in this work two strategies for redundant sensors relocation using mobile robots in
order to improve the connectivity in a wireless sensor network. The main difference between the
proposed strategies is the functioning and the movement adopted by mobile robots to achieve
their mission.
2. RELATED WORK
In recent years, sensor relocation has been a challenging matter that was studied by many
researchers. Several solutions have been proposed to solve the redeployment issue. One relevant
solution was to provide motion capability to all sensors. This way, the sensors can move and
relocate themselves in order to adjust the topology and achieve the connectivity and/or the
coverage. The sensors must synchronize their movement to enhance the network topology.
Among the proposed solutions, we mention particularly the cascade motion which is detailed in
[2]: instead of moving directly to the target, the sensor nodes adopt a cascade movement which
means that the nearest node to the target point will move there, and the location of nearest node is
replaced by moving another sensor and so on. Virtual Forces Aspect has been also proposed as a
solution for sensor relocation. In this way, deployed sensors communicate together and compute
their new locations in order to ensure connectivity and/or coverage. Then these sensors exerce a
repulsive or an attractive force to move to their estimated locations. This strategy was studied and
presented in [18]. The mobility of nodes is very efficient and improves the network topology, but
it requires an important energy consumption which causes the node depletion and decreases the
network lifetime. Other solutions consist of the use of fixed sensor nodes and the network is
assisted by some ”actors” like mobile robots. Some studies, proposed to use the robot to carry
data between disconnected sensors so that robot collects the detected event from nodes and then
delivers these information for the other nodes. This approach is presented by [19]. In this way the
event is delayed and a latency time is introduced which can be considered as a shortcoming for
critical applications.
Another set of related works include algorithms using DATA MULES [14][15], which are
wireless devices integrated on mobile entities (animals, vehicles). A DATA MULE is a data
collector; it picks up data from nodes and relays it to other nodes. So that, data would not be
relayed on long routes and the network lifetime is increased In other proposed solutions, the
actors are advanced mobile sensors that exploit the redundant nodes and relocate them to achieve
better connectivity and /or coverage trying to preserve the network lifetime as long as possible. In
recent years many researches have been interested by sensor relocation to enhance the
connectivity in the WSN.
3. PROPOSED SOLUTION
In our work, we consider particularly a WSN over a risky or unreachable region of interest. We
suppose that the WSN is containing a large number of static sensors which are deployed in the
considered region in a random manner (eg, dropped from an airplane). This deployment leads
generally to the partition of the network, so that the connectivity between nodes is not
guaranteed. We suppose that the position of the sink node is fixed and known. Each sensor has a
communication range noted by rc and a sensing range noted by rs.
We note that, all deployed sensors have the same connectivity range and the same sensing range.
Upon deployment, the position of each sensor is fixed and known by the use of a localization
3. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
3
technique (eg GPS). In our proposed solution, mobile robots are used to relocate redundant nodes
in order to enhance the network connectivity and as a consequence the coverage will be
improved. A mobile robot is a mobile platform which has a large amount of energy and can be
recharged when needed. The robot is also characterized by an important computation capability
and has a communication range noted by Rc. Each mobile robot handles a number of fixed
sensors that can be used to heal connectivity holes. Each robot knows the frontiers of the
controlled area.
After a random deployment over the WSN, the total connectivity between all sensor nodes is not
guaranteed. The resulted network is partitioned. When an event is detected, it may be not
delivered to the sink node. The formed network is composed by a set of disconnected islands,
we call island every set of connected sensor nodes. The Island containing the sink node is called
“MainIsland”. To ensure the connectivity in the WSN, we should connect islands to the
MainIsland. Generally, each Island contains redundant nodes.
3.1. Redundant sensors Identification
To identify redundant nodes, we use hexagonal pavement of the region, sensors belonging to two
adjacent cells are able to communicate. A sensor is said to be redundant if its cell (perception
zone) is covered by other cells.
3.2. Identification of Island-Head
For each Island in the network, an Island-Head is elected. The main role of the Island-Head is to
collect information concerning all sensor nodes belonging to the Island (position of each sensor,
position of redundant nodes, number of redundant nodes, and number of deployed nodes…). To
elect an Island-Head we define criterion described by this equation
where Eres and Emax represent respectively the residual energy and the maximum level of energy
for a given node. Nbn and Nbnodes refer to the number of neighbours of a sensor node and the
numbers of nodes in a given Island. The node with the highest value of f is elected as an Island-
Head. Meaning that, node with the highest amount of energy and having the largest number of
one hop neighbours is chosen as an Island-Head. In case of multiple candidates, the node with
higher Identity is elected. A backup Island-head is chosen to replace Island-Head in case of its
depletion. When the Island-Head is elected, it collects the positions of redundant nodes and these
nodes go to the passive mode (sleeping mode) to save energy of the whole network.
In our solution, we propose to use some robots to relocate redundant sensors and connect Islands
to the MainIsalnd. For this purpose, used robots should communicate together and synchronise
their movements and functions. We propose two strategies for robots to improve the connectivity
in WSN. We call the first one “Multi-Robot Island-Based Relocation” and we note it by
“MRIBR”, in which robots moves is based on Islands. The second strategy is called “Multi-
Robot Grid-Based Island-Based Relocation and is noted by “MRGIR”, with this strategy, in
addition to the island-based model, the controlled area is portioned according to a grid.
4. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
4
4. MULTI-ROBOT ISLAND-BASED RELOCATION
In this solution, we use mobile robots to redeploy sensors in order to improve the connectivity in
WSN. Upon random deployment, the islands are formed and the Island-Heads are elected as
described in the previous section. We remind that, mobile robots have no idea on the network
topology. Nevertheless, each robot is aware by the position of the “sink node”. Robots should
communicate to connect islands to the “MainIsland”.
To achieve their goal, each mobile robot can be in one of the three states:
• Free: the robot walks in the controlled area with a random manner.
• Busy: the robot places and relocates sensors in order to connect an island to the
“MainIsland”.
• Topology Discovery: Periodically, the robot stops (after a distance of 2* Rc and sends a
Hello-Robot Message. Each sensor receiving a ”Hello-Robot”, forwards this message to
its ”Island-Head” and the ”Island-Head” replies with ”Island information” message
containing all information concerning this island (position of nodes, positions of
redundant sensors, sensors identities, number of redundant nodes...).
Each robot starts its work with Topology Discovery state, after sending Hello-Robot message, the
robot waits for a given period.
o If the robot does not receive any reply, it continues its walk in a random direction and
stays in Topology Discovery state.
o If the robot receives an ”Island-information”,
• If the encountered Island is the “Mainland”, the robot memorizes all information
concerning the “MainIsland” and stays in the Topology Discovery state.
• If the encountered Island is an ordinary Island, the robot computes the position of
the nearest node of the ”sink” and then it calculates the number of needed sensors
to connect the island to the “MainIsland”.
• If this requested number of sensors is available on the robot, the robots changed
its state to busy state. It then relocates them (the nodes will be relocated
according to hexagonal pavement).
• If this requested number of sensors is not available on the robot, it continues its
walk in a random manner.
To identify a robot we use an Identity number (ID-Robot) which is assigned to each robot to
make distinction between all robots. Each robot maintains a sequence number for each visited
Island which will be increased after every new visit to an Island.
5. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
5
When a robot places sensors to connect an Island to the “MainIsland”, the robot should verify if
the locations of the sensor is still empty by sending “Hello-Robot” Messages.
After connecting a given Island to the “MainIsland”, all sensors belonging to this Island must
mark their membership to the “MainIsland”.
When a mobile robot encounters redundant sensor nodes, it picks up these sensors unless its
maximum capacity is not reached. We note also that when a mobile robot encounters another one,
it can ask the encountered robot, if needed and possible, to give it some redundant nodes.
5. MULTI-ROBOT GRID-BASED ISLAND-BASED RELOCATION
In this solution, we maintain the concept of Islands and our goal is also to connect all the Islands
to the “MainIsland”. We propose also to divide the controlled area vertically to zones as
described in Figure 1.
Each robot is placed on a zone and knows the frontiers of its zone. Each mobile robot is
responsible of its zone and is not allowed to leaves its zone.
The identification of redundant nodes is made in the same manner like in MRIBR technique and
the placement of nodes in the controlled area is made according to hexagonal pavement.
Figure 1: Network Model
When the sink node belongs to only one zone and when the position of the sink node is known by
all mobile robots, we define Reference Points (RP) which are fictive points replacing sink node in
each zone as described in Figure 1.
Each robot in its zone will function as described in the above section but by replacing the sink
node by RP. Hence a mobile robot will discover its zone and tries to connect discovered Islands
to RP Points. The mobile robot chooses its nearest RP to connect Islands.
6. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
6
For the intermediate zone the robot should also connect its two RP, if they are not already
connected.
Reference Points can be used as points of collect (collection of fixed senors); a mobile robot can
place sensors in these points when the robot has a large number of redundant sensors exceeding
its needs (greater than a predefined threshold).
6. PERFORMANCE EVALUATION
Our proposed solution is implemented under NS2 simulator using MannaSim packages. Several
simulations were established with different scenarios. For all simulations we use a large number
of deployed sensors to ensure full connectivity and coverage over the network. The sensors are
initially deployed randomly through a square ROI, we set rc = rs = 25m and Rc = 60m. We set the
dimension of the Region of Interest to 600*600. The number of deployed sensor nodes is set to
150 sensors in the first time. In a second step, we will vary the number of deployed sensors from
50 to 450 sensors.
To evaluate and compare our proposed strategies MRIBR and MRGIR, we fix a set of metrics
like connectivity time, the average travelled distance by a robot and the connectivity rate.
6.1. Connectivity Time
We note by CT this criterion. Connectivity Time is defined as the needed time to ensure
connectivity in the network. This criterion should be minimized. We present the connectivity
Time according to the number of mobile robots as described in figure 3 and then we present this
connectivity according to the numbers of sensors as described in Figure 2.
Figure 2: Connectivity Time/Numbers of sensors
7. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
7
Figure 3: Connectivity Time/Numbers of robots
Figure 2 and figure 3 show that the curves have the same shape. We remark that, the connectivity
time decreases when the number of sensors and the number of robots increases. This is explained
by when the number of robots increases, the tasks are realized by more than one robot
minimizing the total connectivity time. We remark also that from a given number of robots (4
robots in figure 3), the connectivity time starts to stabilize. We remark also that MRGIR
outperforms MRIBR in term of connectivity Time.
6.2. Average travelled distance
The Average Travelled Distance is the average distance travelled by a mobile robot after
performing the algorithm. It is giving by the following equation
Total Travelled distance by all robots
Number of robots
Figure 4 shows the average travelled distance by a mobile robot according to the number of
sensors. We remark that the travelled distance decreases when the number of deployed sensors
increases. This can be explained by the fact that the number of holes decreases when the number
of deployed sensors increases. Figure 4 shows also that MRGIR outperforms MRIBR.
8. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
8
Figure 4 : Average Travelled Distance/Numbers of sensors
Figure 5 : Average Travelled Distance/Numbers of robots
Figure 5 shows the average travelled distance by a mobile robot according to the number of used
mobile. We remark that the travelled distance decreases when the number of used. But this
numbers starts to be static from a certain threshold.. Figure 5 shows also that MRGIR
outperforms MRIBR.
6.3. Connectivity Rate
The connectivity rate (CR) is he average of connected sensors in the network, this metric should
be maximized to enhance the performance of the tested algorithm. CR is giving by the following
equation:
9. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
9
Number of connected sensors to the MainIsland
Number of deployed sensors
We present the connectivity rate according to the number of mobile robots as described in figure
5 and then we present this connectivity according to the numbers of sensors as described in
Figure 6.
Figure 5: Connectivity Rate/Numbers of robots
Figure 6: Connectivity Rate/Numbers of sensors
10. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
10
We remark that the connectivity rate increases when the number of robots and the number of
sensors increases too. We note also from these figures that MRGIR outperforms MRIBR in terms
of connectivity rate.
6.4 Results Interpretation
Based on the three fixed criteria we show that MRGIR outperforms MRIBR, this can be
explained by the importance of the use of hybrid solution mixing the Island concept with the
Grid-based partition of the controlled area. For MRGIR strategy, the controlled area is divided
into rectangular zones, each zone is handled by one mobile robot. This robot is responsible by
connecting all deployed nodes in its zone. This functioning reduce the responsibility of a mobile
robot comparing to MRIBR strategy in which the movement of robot is not limited to a given
zone and is more random.
Our study can be used especially to analyse the trade-off between the number of robots to use and
the quality of connectivity. Hence, according to the application we can use our configuration.
For example, the needed rate of connectivity for a precision agriculture application is not the
same for a military application in which the total connectivity must be guaranteed.
From this study, we can also determine the optimal number of mobile robots to achieve a given
connectivity time or rate.
Hence through this study we can fix the characteristics of our application like the needed
connectivity time, the minimum connectivity rate and then we can determine the optimal number
of deployed sensors and the optimal number of used robots.
7. CONCLUSION
Ensuring and maintaining connectivity in WSN is a challenging issue especially for WSN in
Hazardous and risky areas like military applications (battlefield survey, intrusion detection). In
this paper, we deal with a WSN deployed with a random manner. This deployment leads to
partition of the networks and a set of disconnected Islands is formed and redundant sensors are
identified.
We propose to use many mobile robots in order to relocate redundant sensors and connect all
nodes in the network. We present two techniques in our work, the first one is an Island-based
technique (MRIBR) and the second one is Grid-based Island-Based strategy (MRGIR), here we
used the concept of islands and we divided into virtual grid, the movement of each robot is made
considering this grid. We show through extensive simulation that MRGIR outperforms MRIBR
in term of connectivity time, connectivity rate and the average travelled distance, this result can
be explained by the fact that in MRGIR strategy, the controlled area is divided in a grid and each
robot is responsible by one zone.
The movement of each robot is limited in one grid. Nevertheless, in MRIBR strategy, the
movement of robot are more random. We notice that our study can be used especially to make a
trade-off between the number of deployed sensors and the numbers of the used mobile robots for
each kind of application. We can also fix the number of needed robots for a given connectivity
11. International Journal of Ad hoc, Sensor & Ubiquitous Computing (IJASUC) Vol.7, No.2, April 2016
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rate and a given connectivity time depending on the type and the specifities of the needed
application.
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