GOVT. COLLEGE OF ENGINEERING AND TEXTILE TECHNOLOGY , BERHAMPORE

GROUP -- 7PRADIP MONDAL(11100112025)PROSENJIT DAS(11100112026)

RAJU KUMAR GIRI(11100112027)RANVEER KUMAR DAS(11100112028)

STREAM : COMPUTER SCIENCE & ENGINEERINGSUBJECT : SEMINAR

YEAR : 3RD (6SEMESTER)

SENSOR NETWORK

Contents1. Definition

2. Components

3. Applications

4. Characteristics

5. Architecture

6. Network architecture

7. Challenges

8. PEGASIS

9. Security

Definition Sensor network ( sometime called Wireless

Sensor Network and Actor Network (WSAN) ) are spatially distributed autonomous sensor to monitor physical or environmental conditions, such as temperature, sound, pressure, etc. and to cooperatively pass their data through the network to a main location. The more modern networks are bi-directional, also enabling control of sensor activity.

Components The WSN is built of "nodes" – from a few to

several hundreds or even thousands, where each node is connected to one (or sometimes several) sensors.

Each such sensor network node has typically several parts: 

Radio TransceiverInternal AntennaExternal AntennaMicrocontrollerPower source (battery)

Sensors

Enabled by recent advances in MEMS technology

Integrated Wireless Transceiver

Limited in Energy ComputationStorageTransmission rangeBandwidth

Battery

Memory

CPU

Sensing Hardware

Wireless Transceiver

Cost : The cost of sensor nodes is similarly variable, ranging

from a few to hundreds of dollars, depending on the complexity of the individual sensor nodes.

Size: It depends on sensor nodes resources such as energy,

memory, computational speed and communications bandwidth.

Topology: The topology of the WSNs can vary from a simple star

network to an advanced multi-hop wireless mesh network Routing and Flooding between the hopes of network is

used for propagation technique

Applications Area Monitoring : In area monitoring, the WSN is deployed over

a region where some phenomenon is to be monitored. A military example is the use of sensors detect enemy intrusion.

Health Care Monitoring : Body-area networks can collect information about an individual's health, fitness, and energy expenditure .

Environmental/Earth Sensing : I. Air pollution monitoringII. Forest fire detectionIII. Land slide detectionIV. Water quality monitoringV. Natural disasterVI. Chemical agent detection

Industrial monitoring and some application in entertainment industry

CharacteristicsThe main characteristics of a WSN include:Power consumption constraints for nodes using

batteries or energy harvestingAbility to cope with node failures (resilience)Mobility of nodesHeterogeneity of nodesScalability to large scale of deploymentAbility to withstand harsh environmental conditionsEase of useCross-layer design

ArchitectureHardware : Low-power microscopic sensors with

wireless communication capability.Miniaturization of computer hardware

IntelligenceMicro Electro-Mechanical Structures (MEMS)

SensingLow-cost CMOS-based RF Radios

Wireless Communications

Overall Architecture of a sensor node

Appl i cati on Layer

Network Layer

MAC LayerPhysi cal Layer

Communi cati onSubSystem

Wi rel ess Channel

Sl ow Seri al Li nk

Sensor

Sensor Node CPU

Radi o Board

Forward Packet Path

Mica2 Wireless SensorsCACM June 2004 pp. 43.

13

New MicaZ follows IEEE 802.15.4 Zigbee standard with direct sequence sprad spectrum radio and 256kbps data rate

MTS310 Sensor Boards• Acceleration, • Magnetic, • Light, • Temperature, • Acoustic,• Sounder

Software ArchitectureWSNs may be deployed in large numbers in

various environments, including remote and hostile regions, where ad hoc communications are a key component. For this reason, algorithms and protocols need to address the following issues:

Increased lifespanRobustness and fault toleranceSelf-configuration

Operating System : Operating systems for wireless

sensor network nodes are typically less complex than general-purpose operating systems. It is possible to use embedded operating systems such as eCos or uC/OS for sensor networks because it has low powered microcontroller available in nodes.

TinyOS is the first operating system designed for wireless sensor networks. TinyOS is based on an event-driven programming model instead of multithreading .

ERIKA Enterprise is an open-source and royalty-free OSEK/VDX  Kernel offering BCC1, BCC2, ECC1, ECC2, multicore, memory protection and kernel fixed priority adopting C programming language .

Online collaborative sensor data management

platforms are on-line database services that allow sensor owners to register and connect their devices to feed data into an online database for storage and also allow developers to connect to the database and build their own applications based on that data.

Simulation of WSN :

At present, agent-based modeling and simulation is the only paradigm which allows the simulation of complex behavior in the environments of wireless sensors (such as flocking). Agent-based simulation of wireless sensor and ad hoc networks is a relatively new paradigm. Agent-based modelling was originally based on social simulation.

Network Architectures

Layer 1

Layer 2

Layer 3

Layered Architecture

BaseStation

Clustered Architecture

BaseStation

Larger Nodes denote Cluster Heads

Cluster architecture (contd.)

( ( ))

( ( ))( ( ))

( ( ))

( ( )) ( ( ))

( ( ))

( ( ))

( ( ))( ( ))

Base Stati on

Cl uster-head

Cl uster-head

Cl uster-head

Sensor

Cl uster

Cl uster

Cl uster

Example - LEACH protocolIt uses two-tier hierarchy

clustering architecture.It uses distributed

algorithm to organize the sensor nodes into clusters.

The cluster-head nodes create TDMA schedules.

Nodes transmit data during their assigned slots.

The energy efficiency of the LEACH is mainly due to data fusion.

Layered Network ArchitectureA few hundred sensor nodes

(half/full duplex)A single powerful base-stationNetwork nodes are organized

into concentric Layers Layer: Set of nodes that have

the same hop-count to the base-station

Additional Mobile Nodes traversing the network

Wireless Multi-Hop Infrastructure Network Architecture (MINA)

A 10 node sensor network depicting cluster of node 3; there are 2 mobile nodes

ChallengesCost and SizeComplexityEnergy management issue :

It is the main challenges regarding WSNI. Actuation energy is the highestII. Communication energy is the next important issueIII. Processor and sensor energy usually less important

Ultra low power sentinel nodes , energy aware data communication and by software nodes minimization technique we can minimize the consumption of energy .

SOME TECHNIQUES ARE USED TO MINIMIZE CHALLENGES AND MOST USED IS PEGASIS :

Goals of PEGASIS (Power-Efficient GAthering for Sensor Information Systems)Minimize distance nodes must transmitMinimize number of leaders that transmit to BSMinimize broadcasting overheadMinimize number or messages leader needs to

receiveDistribute work more equally among all nodes

PEGASISGreedy Chain Algorithm

Start with node furthest away from BSAdd to chain closest neighbor to this node that has

not been visitedRepeat until all nodes have been added to chainConstructed before 1st round of communication

and then reconstructed when nodes diData fusion at each node (except end nodes)

Only one message is passed at every nodeDelay calculation: N units for an N-node network

Sequential transmission is assumed

Start

End

Security In WSN the security is achieved by A secret key algorithm

(sometimes called a symmetric algorithm) is acryptographic algorithm that uses the same key to encrypt and decrypt data.

Conclusion In future it seen that mobile ad-hoc network are use

for larger project because it is more powerful as basically WSN is the subtype of ad-hoc network but WSN is also used with increasing probability as based on requirement. Basically it is used for many smart cities etc.

 

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