Basics of Wireless Sensor Network · “A wireless sensor network (WSN) is a wireless network...

Basics of Wireless Sensor Network

A sensor network is an infrastructure contain sensing(measuring), computing and communication elementsthat gives an administrator the ability to device toobserve and react to events in a specified environment.

There are four basic components in a sensor network:

An Assembly of distributed or localized sensors An interconnecting network (usually wireless-based) A Central point of information clustering A set of computing resources at the central point to

handle data correlation, event movement, statusquerying & data mining.

The technology for sensing and control includes

Electric and magnetic field sensors; Radio-wave frequency sensors Optical-, electrooptic- and infrared sensors; Radars; lasers; location/navigation sensors; Seismic and pressure-wave sensors; Environmental parameter sensors (e.g., wind, humidity,

heat); Biochemical national security–oriented sensors.

Today’s sensors can be described as ‘‘smart’’ inexpensivedevices equipped with multiple onboard sensing elements;they are low-cost, low-power ,multifunctional nodes.

Sensor devices or wireless nodes (WNs) are also called motes . Sensors are internetworked via a series of multihop short-

distance low-power wireless links

Introduction to Wireless Sensor Networks 4

Wireless Sensor Networks are networks that consists

of sensors which are distributed in an adhoc manner.

These sensors work with each other to sense some

physical phenomenon and then the information

gathered is processed to get relevant results.

Wireless sensor networks consists of protocols and

algorithms with self-organizing capabilities.

“A wireless sensor network (WSN) is a wireless

network consisting of spatially distributed

autonomous devices using sensors to cooperatively

monitor physical or environmental conditions, such

as temperature, sound, vibration, pressure, motion

or pollutants, at different locations.”

- Wikipedia

Formed by hundreds or thousands of motes thatcommunicate with each other and pass data along from oneto another

Research done in this area focus mostly on energy awarecomputing and distributed computing

Super Node

Links to Other networks or

Similar Super Nodes

Motes

Environmental/Habitat monitoring

Acoustic detection

Seismic Detection

Military surveillance

Inventory tracking

Medical monitoring

Smart spaces

Process Monitoring

Energy Efficiency

Limited storage and computation

Low bandwidth and high error rates

Errors are common

◦ Wireless communication

◦ Noisy measurements

◦ Node Failure are expected

Scalability to a Large Number of Sensor Nodes

Introduction to Wireless Sensor Networks 11

Power efficiency in WSNs is generally accomplishedin three ways:

1. Low-duty-cycle operation.

2. Local/in-network processing to reduce data volume

3. Multihop networking reduces the requirement forlong-range transmission since signal path loss is aninverse exponent with range or distance. Each nodein the sensor network can act as a repeater, therebyreducing the link range coverage required and, inturn, the transmission power.

MANET WSNMANETs are based on point-to-pointcommunications.

sensor nodes use primarily multicast orbroadcast communication,

They are mobile Sensors generally are not mobile

this is not generally the casein MANETs.

Because the data being collected by multiplesensors are based on common phenomena,there is potentially a degree of redundancy inthe data being communicated by the varioussources in WSNs;

this is not always the case in MANETs, wherethe communicating devices handled by humanusers can be replaced or recharged relativelyoften.

A critical resource constraint in WSNs isenergy;

The number of sensor nodes in a MANETnetwork are less.

The number of sensor nodes in a sensornetwork can be several orders ofmagnitude higher than the nodes in a MANET.

Sensors ◦ Enabled by recent advances in

MEMS technology◦ Integrated Wireless

Transceiver◦ Limited in

Energy

Computation

Storage

Transmission range

Bandwidth

DAWN Lab / UMBC 14

Battery

Memory

CPU

Sensing Hardware

Wireless

Transceiver

DAWN Lab / UMBC 16

DAWN Lab / UMBC 17

Advanced Techniques of Mobile Ad Hoc and Wireless Sensor Networks

Applications of Sensor Networks

Military applications

Monitoring inimical forces

Monitoring friendly forces and equipment

Military-theater or battlefield surveillance

Targeting

Battle damage assessment

Nuclear, biological, and chemical attack detection

Environmental applications

Microclimates

Forest fire detection

Flood detection

Precision agriculture

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Applications of Sensor Networks continue…

Health applications

Remote monitoring of physiological data

Tracking and monitoring doctors and patients inside a hospital

Drug administration

Elderly assistance

Home applications

Home automation

Instrumented environment

Automated meter reading

Commercial applications

Environmental control in industrial and office buildings

Inventory control

Vehicle tracking and detection

Traffic flow surveillance

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Advanced Techniques of Mobile Ad Hoc and Wireless Sensor Networks22

Roles of participants in WSN

Sources of data: Measure data, report them “somewhere”Typically equip with different kinds of actual sensors

Sinks of data: Interested in receiving data from WSN May be part of the WSN or external entity, PDA, gateway, …

Actuators: Control some device based on data, usually also a sink

Advanced Techniques of Mobile Ad Hoc and Wireless Sensor NetworksDAWN Lab / UMBC23

Network Architectures

Layer 1

Layer 2

Layer 3

Layered

Architecture

Base

Statio

n

Clustered

Architecture

Base

Statio

n

Larger Nodes denote Cluster Heads


Protocol Stack for sensor Network

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WSN Protocol Stack

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Layer Name Working

Upper layers In-network applications, including application processing, dataaggregation,external querying query processing, and external database

Layer 4 Transport, including data dissemination and accumulation,caching, andstorage

Layer 3 Networking, including adaptive topology management andtopologicalrouting

Layer 2 Link layer (contention): channel sharing (MAC), timing, andlocality

Layer 1 Physical medium: communication channel, sensing, actuation,and signal processing


WSN Sensor types( Categories)

Category 1 WSNs (C1WSNs)

Category 2 WSNs (C2WSNs)

mesh-based systems with multihopradio connectivity among or between WNs

Point-to-point or multipoint-to-point (starbased) systems generally with single-hop radio connectivity to WNs

Utilizing dynamic routing in both the wireless and wireline portions of the network.

Utilizing static routing over the wireless network; typically, there will be only one route from the WNs to the companion terrestrial or wirelineforwarding node

support highly distributed high-node-count applications(e.g., environmental monitoring, national security systems);

C2WSNs typically support confined short-range spacessuch as a home, a factory, a building, or the human body.

C1WSNs tend to deal with large-scalemultipoint-to-point systems with massive data flows, whereas

C2WSN technology for short-range low-data-rate wireless applications such as RFID (radio-frequency identification) systems, light switches, fire and smoke detectors, thermostats, and, home appliances.

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Category-1 WSN Architecture

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Category 2-WSN architecture

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EXAMPLES OF CATEGORY 2 WSN

APPLICATIONS

1. Home Application

2. Building Automation

3. Industrial Automation

4. Medical Application

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Home Control Automation

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Home Control Automation

Sensing applications facilitate management of lighting, heating, and cooling

systems from anywhere in the home.

Sensing applications automate control of multiple home systems to improve

conservation, convenience, and safety.

Sensing applications capture highly detailed electric, water, and gas utility

usage data.

Sensing applications embed intelligence to optimize consumption of natural

resources.

Sensing applications enable the installation, upgrading, and networking of a

home control system without wires.

Sensing applications enable one to configure and run multiple systems from a

single remote control.

Sensing applications support the straightforward installation of wireless

sensors to monitor a wide variety of conditions.

Sensing applications facilitate the reception of automatic notification upon

detection of unusual events.

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Building Automation

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Building Automation

Sensing applications integrate and centralize management oflighting, heating , cooling, and security (e.g., see Figure 2.6).

Sensing applications automate control of multiple systems toimprove conservation, flexibility, and security.

Sensing applications reduce energy expenses

Sensing applications enable one to allocate utility costsequitably based on actual consumption.

Sensing applications enable the rapid reconfiguring oflighting systems to create adaptable workspaces.

Sensing applications enable the extension and upgrading ofbuilding infrastructure with minimal effort.

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Industrial Control Application

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Industrial Control Application

Industrial automation applications provide control, conservation , efficiency, and safety, as follows:

Sensing applications improve asset management by continuous monitoring of critical equipment.

Sensing applications reduce energy costs through optimized manufacturing processes.

Sensing applications help identify inefficient operation or poorly performing equipment.

Sensing applications help automate data acquisition from remote sensors to reduce user intervention.

Sensing applications provide detailed data to improve preventive maintenance programs.

Sensing applications help deploy monitoring networks to enhance employee and public safety.

Sensing applications help data collection for improved compliance reporting.

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Applications for Industrial and Commercial Spaces Include

Warehouses, fleet management, factories, supermarkets,office complexes

Gas, wat Smoke, CO, and HO detectors

Refrigeration cage or appliance

Equipment management services and preventivemaintenance

Security services

Lighting control

Assembly line and workflow and inventory

Materials processing systems (heat, gas flow, cooling,chemical)

Remote monitoring from corporate headquarters of assets,billing, and energy management

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Medical Application

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Medical Application

A number of hospitals and medical centers are exploringapplications of WSN technology to a range of medical applications,including pre-hospital and in-hospital emergency care, disasterresponse, and stroke patient rehabilitation.

WSNs have the potential to affect the delivery and study of care byallowing vital signs to be collected and integrated automaticallyinto the patient care record and used for real-time triage,correlation with hospital records,

WSNs permit home monitoring for chronic and elderly patients,facilitating long-term care and trend analysis;

This in turn can sometimes reduce the length of hospital stays.

WSNs also permit collection of long-term medical information thatpopulates databases of clinical data; this enables studies acrosspopulations and allows physicians to study the effects of medicalintervention programs

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EXAMPLES OF CATEGORY 1 WSN APPLICATIONS

Military sensor networks to detect and gain as much information as possible about enemy movements, explosions, and other phenomena of interest

Law enforcement and national security applications for inimical agent tracking or nefarious substance monitoring (e.g., see Figure 2.9)

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Law enforcement and national security applications

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EXAMPLES OF CATEGORY 1 WSN APPLICATIONS

Sensor networks to detect and characterize chemical,biological, radiological, nuclear, and explosive (CBRNE)attacks and material

Sensor networks to detect and monitor environmentalchanges in plains, forests, oceans, and so on

Wireless traffic sensor networks to monitor vehicle traffic onhighways or in congested parts of a city

Wireless surveillance sensor networks for providing securityin shopping malls, parking garages

Wireless parking lot sensor networks to determine whichspots are occupied and which are free

Borders monitoring with sensors and satellite uplinks

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Highway Monitoring Application

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Highway Monitoring Application

Traffic Pulse is targeted for open-air environments; itprovides real-time collection of data (e.g., to checktemperature or monitor pollution levels).

The system is installed along major highways; the digitalsensor network gathers lane-by-lane data on travel speeds,lane occupancy, and vehicle counts.

These basic data elements make it possible to calculateaverage speeds and travel times.

The data are then transmitted to the data center forreformatting.

In each major city, Traffic.com maintains a traffic pulseoperations center that collects and reports on real-timeevent, construction, and incident data.

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Military Applications

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Military Applications

Condition-Based Monitoring

Military Surveillance

Borders Monitoring

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Civil and Environmental Engineering Applications

Sensors can be used for civil engineering applications.

Research has been under way in recent years to developsensor technology that is applicable for buildings, bridges,and other structures.

The goal is to develop ‘‘smart structures’’ that are able to self-diagnose potential problems and self-prioritize requisiterepairs

This technology is attractive for earthquake-active zones.

Although routine mild tremors may not cause visibledamage, they can give rise to hidden cracks that couldeventually fail during a higher-magnitude quake.

Furthermore, after a mild earthquake, a building’s truestructural condition may be visible through Smart Dustmotes, tiny and inexpensive sensors

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Wildfire Instrumentation Application

Collecting real-time data from wild fires is important for life

safety considerations and allows predictive analysis of

evolving fire behavior.

One way to collect such data is to deploy sensors in the

wildfire environment.

FireBugs are small wireless sensors (motes) based on TinyOS

that self-organize into networks for collecting real-time data

in wildfire environments

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Habitat Monitoring Application

Monitoring of sensitive wildlife and habitats.

About three dozen motes were deployed on the island.

Each mote has a microcontroller, a low-power radio,memory, and batteries.

Sensor motes monitor and relay their readings into a satellitelink that allows researchers to download real-timeenvironmental data over the Internet.

For habitat monitoring the planner needed sensors that cantake readings for temperature, humidity, barometricpressure, and midrange infrared.

Motes sample and relay their sensor readings periodically tocomputer base stations on the island

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