Wireless Sensor Networks By Ravi Kumar Dasari EECE 505 Term

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Wireless Sensor Networks

• By
• Ravi Kumar Dasari
• EECE 505
• Term Project

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Contents

• Introduction
• Applications of WSN
• Sensor Nodes and Network
• Various Routing Algorithms in WSN
• SPIN Routing
• Simulation using SNetSim
• Conclusions

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Various wireless Networks
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What are WSN?

• Large number of heterogeneous Sensor devices
  spread over a large field.
• Wireless sensing Data Networking. Group of
  sensors linked by wireless media to perform
  distributed sensing tasks

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Applications of WSN

• Military, Environmental, Health (Scanning),
  Space, Exploration,
• Vehicular Movement, Mechanical stress levels on
  attached objects etc.

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Sensor Network and Nodes

• Network Channels User nodes or gateways and
  onward transmission to other network.
• Sensor channels Communicates among sensor nodes
  and targets.
• Sensor Network has three types of Nodes
• Sensor nodes Monitor immediate environment
• Target Nodes Generates various stimuli for
  sensor nodes.
• User Nodes Client and Administration of
  Sensor Networks.

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Sensor Node

• Sense Phenomena
• Process Data
• Communicate Data

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Challenges in WSNs

• Energy
• Computation
• Communication
• Scalability
• Fault Tolerance
• Power Consumption

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Routing in WSN

• They can be divided into two main categories
• Address Centric Finding shortest path between
  pairs of addressable end-nodes.
• Data Centric Finding routes from multiple
  sources to a single sink, allowing data
  aggregation.

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Address Centric
Source 2
Source 1
C
A
B
Sink
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Data Centric
Source 2
Source 1
C
A
B aggregates data from 1 2
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Various Routing Protocols

• Classic Flooding
• Gossiping
• Ideal Dissemination
• SPIN

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Classing Flooding

• Send data to all neighbors.

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Classic Flooding Problems
A
C
B
D

• Implosion Problem A starts by flooding its data
  to all of its neighbors. Two copies of the data
  eventually end at node D. The system wastes
  energy and bandwidth.
• Overlap Problem Two sensors cover an
  overlapping graphic region. When the sensors
  flood their data to node, the Node receives two
  copies of the Data.
• Resource Blinding Resources do not modify their
  activities based on the amount of energy they
  have.

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Gossiping
A
B
C
D

• Gossiping is an alternative to the classic
  flooding approach that uses randomization to
  conserve energy.
• At every step each node only forwards data on to
  one neighbor, which it selects randomly. After
  node D receives the data, it must forward the
  data back to sender (B), otherwise the data would
  never reach node C

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Ideal Dissemination
A
c
a
a,c
B
C
c
a
D

• Ideal Dissemination of observed data a and c.
  Each node in the figure is marked with its
  initial data and boxed number represent the order
  in which data is disseminated. In Ideal
  dissemination both implosion caused by B and Cs
  common neighbor and overlap caused by A and Cs
  overlapping initial data item do not occur.

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SPIN Sensor Protocols for Information Negotiation

• One of the most dominant form of routing in the
  wireless sensor networks.
• Name data, using meta-data
• Meta Data for each sensor data
• Same senor data -gt same meta-data
• Different sensor data -gt different meta-data
• Size of meta-data ltlt Size of actual data
• Uses three types of messages
• ADV advertise data
• REQ request for data
• DATA data message, contains actual sensor data

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SPIN1 and SPIN2

• SPIN1 Three way handshaking protocol. ADV,
  REQ, DATA.
• Each sensor node has resource manager
• Keeps track of resource consumption
• Applications probe the manager before any
  activity
• Cut down activity to save energy
• SPIN2 energy constraint
• Adds energy-conservative heuristic to the SPIN1
  protocol.
• Node initiates three stage protocol, only if it
  has enough energy to complete it.
• If below energy threshold, node can still receive
  messages, cannot send/recv DATA messages

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• Node B sends a REQ listing all of the data it
  would like to acquire.

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If node B had its own data, it could aggregate
this with the data of node A and advertise.
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• Nodes need not respond to every message

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Simulators available for WSN

• JavaSim Easy to use, very modular but no
  wireless support.
• GlomoSim Specific for wireless networks, layer
  architecture, but too robust to be used for small
  networks.
• NS-2 Supports wireless simulations, lots of good
  documentation, But difficult to use, we need to
  create separate modules for each protocol.
• SNetSim New simulation software, mainly for
  event driven conditions, simple and easy to use,
  can create our own protocols.

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SNetSim

• SNetSim is a event-driven simulation software
  running on Windows based operating systems.
  Developed at Naval Science and Engineering
  Institute (Turkey)

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Conclusions

• SPIN is simple to implement compared with other
  protocols.
• SPIN seems to be the best protocol. It is better
  than flooding because it overcomes data implosion
  and overlap.
• More energy-efficient than flooding or gossiping
  while distributing data at the same rate or
  faster than either of these protocols.
• These is no redundant data sent through the
  network.

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Reference

• SNetSim Software from http//www.dho.edu.tr/enstit
  unet/snetsim/index.htm
• Routing Issues from http//www.rystal.uta.edu/ku
  mar/cse6392/termpapers/Kalyani_paper.pdf
• SPIN issues from http//www.r2.cs.ucla.edu/seap
  ahn/papers/sensor_nets.pdf

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Question?