Viraj Anagal Kaushik Mada Presented to Dr. Mohamed Mahmoud ECE 6900 - - PowerPoint PPT Presentation

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Viraj Anagal Kaushik Mada Presented to Dr. Mohamed Mahmoud ECE 6900 - - PowerPoint PPT Presentation

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Presented by Viraj Anagal Kaushik Mada Presented to Dr. Mohamed Mahmoud ECE 6900 Fall 2014 Date: 09/29/2014 1 Outline Motivation Overview Wireless Sensor Network Components Characteristics of Wireless Sensor Network

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Presented by

Viraj Anagal Kaushik Mada

Presented to

  • Dr. Mohamed Mahmoud

ECE 6900 Fall 2014 Date: 09/29/2014

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Outline

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Motivation

  • Sensors integrated into systems.
  • Efficient delivery of sensed information.
  • Limiting the number of sensors that may be deployed.
  • Fewer catastrophic failures.
  • Conservation of natural resources.
  • Improved manufacturing productivity,
  • Improved emergency response
  • Enhanced homeland security

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Overview

A Wireless Sensor Network (WSN) consists of base stations and a number of wireless sensors (nodes). Data is collected at the wireless sensor node, compressed, and transmitted to the gateway directly. If required, uses other wireless sensor nodes to forward data to the gateway.

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Wireless Sensor Network Components

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Characteristics Of WSN

  • Requirements: small size, large number, tether‐less, and low cost.
  • The ideal wireless sensor is networked and scaleable, consumes very

little power.

  • Is smart and software programmable, capable of fast data acquisition,

reliable and accurate over the long term.

  • Costs little to purchase and install, and requires no real maintenance.
  • Examples of low data rate sensors include temperature, humidity, and

peak strain captured passively.

  • Examples of high data rate sensors include strain, acceleration, and

vibration. Constrained by

  • Energy, computation, and communication
  • Small size implies small battery
  • Low cost & energy implies low power CPU, radio with minimum

bandwidth and range

  • Ad‐hoc deployment implies no maintenance or battery replacement
  • To increase network lifetime, no raw data is transmitted

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Individual Wireless Sensor Node Architecture

  • Sensor event‐driven data collection model minimizes the power consumed by the

system.

  • Depending on the sensors to be deployed, the signal conditioning block can be re‐

programmed or replaced.

  • The radio link may be swapped out as required for a given applications wireless range

requirement and the need for bidirectional communications.

  • The use of flash memory allows the remote nodes to acquire data on command from a

base station, or by an event sensed by one or more inputs to the node.

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Role of Microprocessors or Embedded Systems

  • The Microcontroller Unit (MCU) is the primary choice for in‐node

processing

  • Power consumption is the key metric in MCU selection.
  • The MCU should be able to sleep whenever possible, like the radio.
  • Memory requirements depend on the application
  • ATmega128L and MSP430 are popular choices
  • Managing data collection from the sensors
  • Performing power management functions
  • Interfacing the sensor data to the physical radio layer
  • Managing the radio network protocol.
  • The hardware should be designed to allow the microprocessor to

judiciously control power to the radio, sensor, and sensor signal conditioner.

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Radio

  • Commercially‐available chips
  • Available bands: 433 and 916MHz, 2.4GHz ISM bands
  • Typical transmit power: 0dBm.

Power Control

  • Sensitivity: as low as ‐110dBm
  • Narrowband (FSK) or Spread Spectrum communication. DS‐SS (e.g.,

ZigBee) or FH‐SS (e.g., Bluetooth)

  • Relatively low rates (<100 kbps) save power.

Power Supply

  • AA batteries power the vast majority of existing platforms. They dominate the node

size.

  • Alkaline batteries offer a high energy density at a cheap price. The discharge curve is

far from flat, though.

  • Lithium coin cells are more compact and boast a flat discharge curve.
  • Rechargeable batteries: Who does the recharging?
  • Solar cells are an option for some applications.
  • Fuel cells may be an alternative in the future.
  • Energy scavenging techniques are a hot research topic (mechanical, thermodynamical,

electromagnetic).

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Wireless Sensor Networks Architecture

  • Star Network (Single Point‐to‐Multipoint)
  • Mesh Network
  • Hybrid Star – Mesh Network

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Wireless Sensor Networks Architecture

Star Network (Single Point‐to‐Multipoint)

  • A single base station can send and/or receive a message to a number of remote nodes.
  • The remote nodes can only send or receive a message from the single basestation,

they are not permitted to send messages to each other.

  • Advantages
  • Is in its simplicity and the ability to keep the remote node’s power consumption

to a minimum.

  • low latency communications between the remote node and the basestation.
  • Disadvantages
  • Basestation must be within radio transmission range of all the individual nodes
  • Not as robust as other networks due to its dependency on a single node to

manage the network.

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Wireless Sensor Networks Architecture Cont.

Mesh Network

  • Any node in the network to transmit to any other node in the network that is within its

radio transmission range.

  • This allows for what is known as multihop communications
  • It can use an intermediate node to forward the message to the desired node.
  • Advantages
  • Redundancy and Scalability
  • The range of the network is not necessarily limited by the range in between single

nodes.

  • Disadvantages
  • Power consumption is higher for multihop communications.
  • Limited battery life.
  • The time to deliver the message also increases due to increase in nodes in path.

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Wireless Sensor Networks Architecture Cont.

Hybrid Star – Mesh Network

  • The lowest power sensor nodes are not enabled with the ability to forward messages.
  • This allows for minimal power consumption to be maintained.
  • Other nodes on the network are enabled with multihop capability, allowing them to

forward messages from the low power nodes to other nodes on the network.

  • Generally, the nodes with the multihop capability are higher power, and if possible, are
  • ften plugged into the electrical mains line.
  • This topology is implemented by the coming mesh networking standard known as

ZigBee.

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Wireless Sensor Networks Architecture Cont.

Hybrid Star – Mesh Network

  • The lowest power sensor nodes are not enabled with the ability to forward messages.
  • This allows for minimal power consumption to be maintained.
  • Other nodes on the network are enabled with multihop capability, allowing them to

forward messages from the low power nodes to other nodes on the network.

  • Generally, the nodes with the multihop capability are higher power, and if possible, are
  • ften plugged into the electrical mains line.
  • This topology is implemented by the coming mesh networking standard known as

ZigBee.

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Radio Options for the Physical Layer in Wireless Sensor Networks

  • IEEE802.11x
  • Bluetooth (IEEE802.15.1 and .2)
  • IEEE 802.15.4
  • ZigBee
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Radio Options for the Physical Layer in Wireless Sensor Networks

IEEE802.11x

  • local area networking for relatively high bandwidth data transfer between computers
  • r other devices.
  • The data transfer rate ranges from as low as 1 Mbps to over 50 Mbps.
  • Typical transmission range is 300 feet with a standard antenna.
  • Both frequency hopping and direct sequence spread spectrum modulation schemes

are available.

  • While the data rates are certainly high enough for wireless sensor applications, the

power requirements generally preclude its use in wireless sensor applications.

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Radio Options for the Physical Layer in Wireless Sensor Networks

Bluetooth (IEEE802.15.1 and .2)

  • Bluetooth is a personal area network (PAN) standard that is lower power than 802.11.
  • Bluetooth uses a star network topology that supports up to seven remote nodes

communicating with a single basestation.

  • Limitations of Bluetooth in WSN
  • Relatively high power for a short transmission range.
  • Nodes take a long time to synchronize to network when returning from sleep

mode, which increases average system power.

  • Low number of nodes per network (<=7 nodes per piconet).
  • Medium access controller (MAC) layer is overly complex when compared to that

required for wireless sensor applications.

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Radio Options for the Physical Layer in Wireless Sensor Networks

IEEE 802.15.4

  • The 802.15.4 standard was specifically designed for the requirements of wireless

sensing applications.

  • It specifies multiple data rates and multiple transmission frequencies.
  • The power requirements are moderately low.
  • The hardware is designed to allow for the radio to be put to sleep, which reduces

the power to a minimal amount

  • When the node wakes up from sleep mode, rapid synchronization to the network

can be achieved.

  • Characteristics of IEEE 802.15.4
  • Transmission frequencies, 868 MHz/902–928 MHz/2.48–2.5 GHz.
  • Data rates of 20 Kbps (868 MHz Band) 40 Kbps (902 MHz band) and 250 Kbps (2.4

GHz band).

  • Supports star and peer‐to‐peer (mesh) network connections.
  • Standard specifies optional use of AES‐128 security for encryption of transmitted

data.

  • Link quality indication, which is useful for multi‐hop mesh networking algorithms.

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Radio Options for the Physical Layer in Wireless Sensor Networks

ZigBee

  • The ZigBee alliance specifies the IEEE 802.15.4 as the physical and MAC layer and

is seeking to standardize higher level applications such as lighting control and HVAC monitoring.

  • The ZigBee network specification, to be ratified in 2004, will support both star network

and hybrid star mesh networks.

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Power Consideration in Wireless Sensor Networks

  • Fig. shows a chart outlining the major contributors to power consumption in a typical

5000‐ohm wireless strain gage sensor node versus transmitted data update rate.28

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Power Consideration in Wireless Sensor Networks Cont.

  • The single most important consideration for a wireless sensor network is power

consumption.

  • There are a number of strategies that can be used to reduce the average supply

current of the radio, including:

  • Reduce the amount of data transmitted through data compression and reduction.
  • Lower the transceiver duty cycle and frequency of data transmissions.
  • Reduce the frame overhead.
  • Implement strict power management mechanisms (power‐down and sleep

modes).

  • Implement an event‐driven transmission strategy; only transmit data when a

sensor event occurs.

  • Power reduction strategies for the sensor itself include:
  • Turn power on to sensor only when sampling.
  • Turn power on to signal conditioning only when sampling sensor.
  • Only sample sensor when an event occurs.
  • Lower sensor sample rate to the minimum required by the application.

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OUTLINE

  • Motivation
  • Overview
  • Wireless Sensor Network Components
  • Characteristics of Wireless Sensor Network
  • Individual Wireless Sensor Network Architecture
  • Role of Micro Processors or Embedded Systems
  • Wireless Sensor Network Architectures
  • Radio options for Wireless Sensor Network
  • Power considerations in Wireless Sensor Network
  • Applications of Wireless Sensor Network
  • Conclusion
  • References

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Applications of Wireless Sensor Networks

  • Structural Health Monitoring – Smart Structures
  • Industrial Automation
  • Civil Structure Monitoring
  • Environmental Monitoring
  • Medical Application
  • Military and national security application
  • Nearly anything you can imagine…
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Applications of Wireless Sensor Networks

Structural Health Monitoring – Smart Structures

  • Wireless sensing will allow assets to be inspected when the sensors indicate that there

may be a problem, reducing the cost of maintenance and preventing catastrophic failure in the event that damage is detected.

  • The use of wireless reduces the initial deployment costs, as the cost of installing long

cable runs is often prohibitive.

  • Wireless sensing applications demand the elimination of not only lead wires, but the

elimination of batteries as well, due to the inherent nature of the machine, structure,

  • r materials under test.
  • These applications include sensors mounted on continuously rotating parts, within

concrete and composite materials, and within medical implants.

  • Sensors embedded into machines and structures enable condition‐based maintenance
  • f these assets

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Applications of Wireless Sensor Networks

Industrial Automation

  • The use of wireless sensors allows for rapid installation of sensing equipment and

allows access to locations that would not be practical if cables were attached.

  • Other applications include energy control systems, security, wind turbine health

monitoring, environmental monitoring, location‐based services for logistics, and health care.

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Applications of Wireless Sensor Networks

Civil Structure Monitoring

  • One of the most recent applications of today’s smarter, energy‐aware sensor networks

is structural health monitoring of large civil structures, such as the Ben Franklin Bridge which spans the Delaware River, linking Philadelphia and Camden, N.J

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Applications of Wireless Sensor Networks

Environmental Monitoring 1

  • 150 sensing nodes deployed throughout the island relay data temperature, pressure,

and humidity to a central device.

  • Data was made available on the Internet through a satellite link.

Great Duck Island

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Applications of Wireless Sensor Networks

Environmental Monitoring 2

  • Special GPS‐equipped collars were attached to zebras
  • Data exchanged with peer‐to‐peer info swaps
  • Coming across a few zebras gives access to the data

Zebranet: a WSN to study the behavior of zebras

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Applications of Wireless Sensor Networks

Medical Application

  • Intel deployed a 130‐node network to monitor the activity of residents in an elder care

facility.

  • Patient data is acquired with wearable sensing nodes (the “watch”)
  • Vital sign monitoring
  • Accident recognition
  • Monitoring the elderly

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Conclusion

  • Wireless sensor networks are enabling applications that previously were not practical.
  • As new standards‐based networks are released and low power systems are continually

developed, we will start to see the widespread deployment of wireless sensor networks.

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References

  • Wireless sensor networks

http://210.32.200.159/download/20100130212654891.pdf

  • Wireless Sensor Network Topologies

http://archives.sensorsmag.com/articles/0500/72/

  • A Standard Smart Transducer Interface ‐ IEEE 1451

http://ieee1451.nist.gov/Workshop_04Oct01/1451_overview.pdf

  • New technological vistas for systems and control: the example of wireless networks

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=898790

  • http://searchdatacenter.techtarget.com/definition/sensor‐network
  • Wireless Sensor Networks: Principles and Applications

http://booksite.elsevier.com/9781856175302/errata/003~Wireless_Systems.pdf

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Thank You!

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Questions???

  • Can you think of any applications where a wireless sensor network would be the best

solution?

  • Do you foresee wireless sensor networks becoming ubiquitous within the next ten

years? During your lifetime?

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