SENSOR NODE ARCHITECTURE AND WSN

CLUSTERING

Presented By: Shubhi Singh P14EC021

REVIEW• Getting Known to WSN Environment• Applications of WSN• Differences with ad hoc networks• Characteristics• Challenges• Sources of energy Inefficiency• WSN Routing Protocols• Future• Hardware Setup Overview

OUTLINE What is sensor node? Sensor node architecture Description of Main components of a wireless

sensor node Processor, radio, sensors, batteries

Energy supply WSN Clustering Clustering Objective Brief Of Leach Protocol

SENSOR NODEA sensor node, also known as a mote (chiefly in North America), is a node in a wireless sensor network that is capable of performing some processing, gathering sensory information and communicating with other connected nodes in the network. 

MICA2 NodeMICA2 Node

MAIN COMPONENTS

NODE ARCHITECTURENODE ARCHITECTURE

ADC converts the output of a sensor - which is a ADC converts the output of a sensor - which is a continuous, analog signal - into a digital signal. It requires continuous, analog signal - into a digital signal. It requires two steps:two steps:

1.1. the analog signal has to be quantizedthe analog signal has to be quantized allowable discrete values is influenced :allowable discrete values is influenced :

(a) by the frequency and magnitude of the signal(a) by the frequency and magnitude of the signal (b) by the available processing and storage resources(b) by the available processing and storage resources

2.2. the sampling frequency the sampling frequency Nyquist rate does not suffice because of noise and transmission errorNyquist rate does not suffice because of noise and transmission error resolution of ADC - an expression of the number of bits that can be used to resolution of ADC - an expression of the number of bits that can be used to

encode the digital outputencode the digital output

where Q is the resolution in volts per step (volts per output code); where Q is the resolution in volts per step (volts per output code); EppEpp is the peak-to-peak analog voltage; is the peak-to-peak analog voltage; MM is the ADC’s resolution in bits is the ADC’s resolution in bits

Sensor SubsystemSensor Subsystem

PROCESSOR SUBSYSTEM The processor subsystem

interconnects all the other subsystems and some additional peripheries

its main purpose is to execute instructions pertaining to sensing, communication, and self-organization

It consists of processor chip nonvolatile memory - stores program instructions active memory - temporarily stores the sensed data internal clock

Major Options For Processors:

Microcontroller – general purpose processor, optimized for embedded applications, low power consumption

DSP – optimized for signal processing tasks, not suitable here(some tasks require protocols (and not numerical operations) that require periodical upgrades or modifications (i.e. the networks should support flexibility in network programming)

FPGA – may be good for testing(complex and costly)

ASIC – only when peak performance is needed, no flexibility (high development costs and lack of re-configurability)

COMPARISON

Working with a micro-controller is preferred if the design goal is Working with a micro-controller is preferred if the design goal is to achieve flexibilityto achieve flexibilityWorking with the other mentioned options is preferred if power Working with the other mentioned options is preferred if power consumption and computational efficiency is desiredconsumption and computational efficiency is desiredDSPs are expensive, large in size and less flexible; they are best DSPs are expensive, large in size and less flexible; they are best for signal processing, with specific algorithmsfor signal processing, with specific algorithmsFPGAs are faster than both microcontrollers and digital signal FPGAs are faster than both microcontrollers and digital signal processors and support parallel computing; but their production processors and support parallel computing; but their production cost and the programming difficulty make them less suitablecost and the programming difficulty make them less suitableASICs have higher bandwidths; they are the smallest in size, ASICs have higher bandwidths; they are the smallest in size, perform much better, and consume less power than any of the perform much better, and consume less power than any of the other processing types; but have a high cost of production owing other processing types; but have a high cost of production owing to the complex design processto the complex design process

COMMUNICATION INTERFACES

The choice is often between serial interfaces : Serial Peripheral Interface (SPI) General Purpose Input/Output (GPIO) Secure Data Input/Output (SDIO) Inter-Integrated Circuit (I2C)

Among these, the most commonly used buses are SPI and I2C

TRANSCEIVER CHARACTERISTICS

Service to upper layer: packet, byte, bit

Power consumption Supported frequency,

multiple channels Data rate Modulation Power control Communication range etc.

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

TRANSCEIVER STATES

Transceivers can be put into different operational states, typically:

TransmitTransmit ReceiveReceive IdleIdle – ready to receive,

but not doing so SleepSleep – significant parts

of the transceiver are switched off

RxRxTxTx IdleIdle

SleepSleep

SENSORS Main categories

Passive, omnidirectional Passive, omnidirectional Examples: light, thermometer, microphones,

hygrometer, … Passive, narrow-beamPassive, narrow-beam

Example: Camera Active sensorsActive sensors

Example: Radar Important parameter: Area of coverage

Which region is adequately covered by a given sensor?

ENERGY SUPPLY

Goal: provide as much energy as possible at smallest cost/volume/weight/recharge time/longevity

In WSN, recharging may or may not be an option Options

Primary batteriesPrimary batteries – not rechargeable Secondary batteriesSecondary batteries – rechargeable, only makes

sense in combination with some form of energy harvesting

ENERGY SUPPLY - REQUIREMENTS

Low self-discharge Long shelf life Capacity under load Efficient recharging at low current Good relaxation properties (seeming self-

recharging) Voltage stability (to avoid DC-DC conversion)

PORTABLE SOLAR CHARGERS Foldable Solar Chargers

http://www.energyenv.co.uk/FoldableChargers.asp

Solargorilla http://powertraveller.com/iwantsom

e/primatepower/solargorilla/

SUMMARY

The need to build cheap, low-energy, (small) devices has various consequences Much simpler radio frontends and

controllers Energy supply and scavenging are a

premium resource Power management is crucial

WHAT IS CLUSTERING

• Nodes divided in virtual group according to some rulesNodes divided in virtual group according to some rules• Nodes belonging in a group can execute different Nodes belonging in a group can execute different

functions from other nodes.functions from other nodes.

Cluster memberCluster member

ClusterheadClusterhead

Gateway nodeGateway node

Intra-Cluster linkIntra-Cluster link

Cross-cluster Cross-cluster linklink

Clustering ObjectivesClustering Objectives::

•Allows aggregationAllows aggregation•Limits data transmissionLimits data transmission•Facilitate the reusability of the resourcesFacilitate the reusability of the resources•CHs and gateway nodes can form a virtual CHs and gateway nodes can form a virtual backbone for intercluster routingbackbone for intercluster routing•Cluster structure gives the impression of a Cluster structure gives the impression of a smaller and more stable networksmaller and more stable network•Improve network lifetimeImprove network lifetime• Reduce network traffic and the contention Reduce network traffic and the contention

for the channelfor the channel• Data aggregation and updates take place Data aggregation and updates take place

in CHsin CHs

LITERATURE SURVEY OF CLUSTERING ALGORITHMS • HEED: A hybrid energy efficient distributed clustering HEED: A hybrid energy efficient distributed clustering

approach for ad-hoc sensor networksapproach for ad-hoc sensor networks

• MRECA: Mobility resistant efficient clustering approach MRECA: Mobility resistant efficient clustering approach for ad-hoc sensor networksfor ad-hoc sensor networks

• Energy efficient dynamic clustering algorithm for ad-hoc Energy efficient dynamic clustering algorithm for ad-hoc sensor networks sensor networks

• LEACH-Energy efficient communication protocol for WSNLEACH-Energy efficient communication protocol for WSN

• EEDC-Dynamic clustering and energy efficient routing EEDC-Dynamic clustering and energy efficient routing technique for WSNtechnique for WSN

LEACH PROTOCOL

LEACH ProtocolLEACH Protocol

Intracluster – Intercluster Intracluster – Intercluster communicationcommunication

HEED ProtocolHEED Protocol

REFERENCES

A hybrid energy efficient distributed clustering approach for ad-hoc sensor networks Node Clustering in Wireless Sensor Networks by Considering Structural Characteristics of

the Network Graph, Nikos Dimokas,Dimitrios Katsaros,Yannis Manolopoulos, 4th ITNG Conference, Las Vegas, NV, 2-4/April/2007

On Energy Efficiency in Collaborative Target Tracking in Wireless Sensor Network: A Review, Demigha, O. ; Ecole Militaire Polytech., Algiers, Algeria ; Hidouci, W.-K. ; Ahmed, T., IEEE Communications Society, 31 July 2013

Analysis and design of energy-oriented security protocols for Wireless Sensor Networks, Guo Xiaowang ; Zhu Jianyong (Electronic and Mechanical Engineering and Information Technology (EMEIT), 2011 International Conference on ),Volume: 5 , 2011

Fundamental of Wireless Sensor Network:theory and practical by Waltenegus Dargie and Christian paullabauer @2010.