August 24, 2006Talk at SASTRA1 Wireless Sensor Network Prabhakar Dhekne Bhabha Atomic Research...
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Transcript of August 24, 2006Talk at SASTRA1 Wireless Sensor Network Prabhakar Dhekne Bhabha Atomic Research...
August 24, 2006 Talk at SASTRA 1
Wireless Sensor Network
Prabhakar Dhekne
Bhabha Atomic Research Centre
August 24, 2006 Talk at SASTRA 2
Why Talk About Wireless?
Wireless communication is not a new technology but cell phones have brought revolution in wireless communication
Wireless Technology has changed the way Organizations & individuals work & live today
In less than 10 years World has moved from fixed to wireless networks Allowing people, mobile devices & computers talk to each other,
connect without a cable Only available option for field data acquisition
Interconnectivity with multiple devices Using radio-waves, sometimes light Frees user from many constrains of traditional computer &
phone system
August 24, 2006 Talk at SASTRA 3
Ubiquitous Computing
Future State of Computing Technology? Mobile, many computers Small Processors Low Power Consumption Relatively Low Cost
August 24, 2006 Talk at SASTRA 4
Ubiquitous Computing
Small, mobile, inexpensive computers…..everywhere!
Fade into the background of everyday life Computers everywhere provides potential for data
collection….sensors! Temperature Light Sound Motion Pressure Many others!!!
August 24, 2006 Talk at SASTRA 5
Growth in Wireless Systems
Rapid growth in cellular voice services Cell phones everywhere!
Several wireless technology options have been available for the last ~10-20 yrs mini cell stations using existing standards like CDMA or
GSM wireless PABX using PCS standards such as DECT or
PHS/PACS satellite and microwave backhaul
Above solutions OK for voice & low-speed data, but do not meet emerging needs for broadband access and mobile data
August 24, 2006 Talk at SASTRA 7
Mobile Healthcare Technologies
Mobile Healthcare can be regarded as the integration of technologies of medical sensors, mobile computing, and wireless communications into a system of medical assistance.
August 24, 2006 Talk at SASTRA 8
Application Examples
Monitoring of patient’s vital signs Diabetes Asthma Hypertension ECG
Predictive usage in order to minimize the needs for medication
Improving the quality of life
August 24, 2006 Talk at SASTRA 9
Potential Benefits Increasing the physician productivity and
efficiency. Wireless sensors enable the patients’
freedom of movements and therefore promote new ways of monitoring the patient.
Providing clinicians remote access to patient’s information eliminates the need to manually locate and search through patient’s data.
Enabling telemonitoring in emergency scenarios and making remote diagnosis possible.
August 24, 2006 Talk at SASTRA 10
The provision of Real Time patient care. No matter where the clinician is No matter where the patient is To apply physiological and medical knowledge,
advanced diagnostics, simulations, and effector systems integrated with information and telecommunications for the purposes of enhancing operational and medical decision-making, improving medical training, and delivering medical treatment across all barriers
Mobile Healthcare
August 24, 2006 Talk at SASTRA 11
Typical Demo System
The patient is provided with a wearable wireless sensor. The signal from the sensor is captured in a Node situated in a mobile phone.
The system allows ubiquitous access to patient’s data and medical information in real-time via the mobile phone.
The medical data is stored & processed in a server, and can be used for establishing diagnostics and treatments.
August 24, 2006 Talk at SASTRA 12
Application server Application server centralises the
received data and presents it to the user as: Raw data Formatted as graphs
DB
App Server
August 24, 2006 Talk at SASTRA 13
Wireless Technology
Emerging mainstream wireless technologies provide powerful building blocks for next-generation applications
WLAN (IEEE 802.11 “WiFi”) hot-spots for broadband access, Bluetooth PDAs and laptops with integrated WLANs
Broadband Wireless access technology- MAN (Alternative to DSL) IEEE 802.16 10-30 Km 40 Mbps WiMax
Wide area wireless data also growing SMS, GPRS, Edge, CDMA2000 1xEV-DO (2.4 Mbps data optimized) Variety of interesting devices (e.g. Treo, Sidekick)
Networking of embedded devices Smart spaces, sensor networks (IEEE 802.15.4a- ZigBee) Context-aware mobile data services and web caching for information
services Wireless sensor nets for monitoring and control VOIP for integrated voice services over wireless data networks
August 24, 2006 Talk at SASTRA 14
IrDA: P2P wirelessIrDA: P2P wireless Infra-red Data Association
Based on Half Duplex Point-to-Point concept Frequency below the red end of spectrum
making it invisible Eliminate the need for cables Clear line-of-sight Short-range (few meters)
Simplest, most prevailing wireless standard
No fixed speed 9.6 Kbps, 4Mbps Discovery Mode to find out data rate, size Token based transmission IrDA ports on PDA, Laptops USB sticks Remote Control in TV, VCR, Air-conditioner
Port costs less than Rs. 1000
August 24, 2006 Talk at SASTRA 15
Bluetooth: Wireless PAN Bluetooth: Wireless PAN
M1
Bluetooth (Named after Danish King Harold Bluetooth)
Based on Master-Slave concept Short-range (10 meters) Eliminate the need for cables Operates in 2.4 GHz ISM band 720 Kbps Three modes of operation park/hold/sniff
Piconet & Scatternet (master+7 slaves) Interference due to multiple piconets
and IEEE 802.15.1 home/person LAN To eliminate interference frequency
hoping technique used Ominidirectional with both voice &
data Port costs about Rs. 2000
Piconet 1 Piconet 2
S1
M 1/S1
S2
S2
S1
August 24, 2006 Talk at SASTRA 16
Wi-Fi: Wireless LAN (Hot Wi-Fi: Wireless LAN (Hot Spot)Spot)
Wireless Fidelity based LAN Most popular on Laptops Replacement to wired LAN Connectivity on the move Short-range (100 meters) Ad Hoc and Base station mode Security provided at physical layer Operates in 2.4 GHz and 5 GHz
Collection of IEEE standards 802.11a/b/g 11 Mpbs & 54 Mbps
Low range, requires more power hence not suitable for PDA’s
Difficult to control access & security
Set up is expensive
Ad Hoc Net
Access Point Net
August 24, 2006 Talk at SASTRA 17
Wi-Max: Wireless MAN Wi-Max: Wireless MAN
Wireless Max High Speed 40-70 Mbps Mid-range (30 Kmeters) Eliminate the need for cables Saving of wired cost Operates in 2.4 GHz ISM band
IEEE standard 802.16
August 24, 2006 Talk at SASTRA 18
Issues in Wireless Networking
Infrastructured networks Handoff location management (mobile IP) channel assignment
August 24, 2006 Talk at SASTRA 19
Issues in Wireless Networking
Infrastructureless networksWireless MAC Security (integrity, authentication, confidentiality)
Ad Hoc Routing Protocols Multicasting and Broadcasting
August 24, 2006 Talk at SASTRA 20
Indoor Environments
Three popular technologies
- High Speed Wireless LANs (802.11b (2.4GHz,
11 Mbps), 802.11a (5GHz, 54 Mbps & higher)
- Wireless Personal area Networks PANs (IEEE 804.14)
HomeRF Bluetooth, 802.15
- Wireless device networks Sensor networks, wirelessly networked robots
August 24, 2006 Talk at SASTRA 21
What is an Ad hoc Network
Collection of mobile wireless nodes forming a network without the aid of any infrastructure or centralized administration
Nodes have limited transmission range Nodes act as a routers
August 24, 2006 Talk at SASTRA 22
Ad Hoc Networks
Rapidly deployable infrastructure Wireless: cabling impractical Ad-Hoc: no advance planning
Backbone network: wireless IP routers • Network of access devices
• Wireless: untethered
• Ad-hoc: random deployment
• Edge network: Sensor networks, Personal Area Networks (PANs), etc.
• Disaster recovery
• Battlefield
• ‘Smart’ office
August 24, 2006 Talk at SASTRA 23
Ad Hoc Network Characteristics
Dynamic topologies Limited channel bandwidth Variable capacity links Energy-constrained operation Limited physical security
Applications Military battlefield networks Personal Area Networks (PAN) Disaster and rescue operation Peer to peer networks
August 24, 2006 Talk at SASTRA 24
Security Challenges in Ad Hoc Networks
Lack of Infrastructure or centralized control Key management becomes difficult
Dynamic topology Challenging to design sophisticated & secure
routing protocols Communication through Radio Waves
Difficult to prevent eavesdropping Vulnerabilities of routing mechanism
Non-cooperation of nodes Vulnerabilities of nodes
Captured or Compromised
August 24, 2006 Talk at SASTRA 25
Security
Challenges in ad hoc network security The nodes are constantly mobile The protocols implemented are co-operative in nature There is a lack of a fixed infrastructure to collect audit
data No clear distinction between normalcy and anomaly in ad
hoc networks Secure the Routing Mechanism
A mechanism that satisfies security attributes like authentication, confidentiality, non-repudiation and integrity
Secure the Key Management Scheme Robust key certification and key distribution mechanism
August 24, 2006 Talk at SASTRA 26
Scalable, reliable, consistent, distributed
service
Calendar+ service Integrate dynamic traffic & schedule
Doctor prescription servicetrack health indicatorsDoctor write prescription
Follow me kiosk service receive and transmit messages
Fridge & shopping serviceFridge records stockSuggests shopping based on recipeShopping guide in store
Sensor services exercise monitorbiometrics traffic information
services
Sensors mobile devices
Services while on move
August 24, 2006 Talk at SASTRA 27
Tourist guide
Stuttgart tourist guide Like MapQuest except on mobile
device Mapping local interests
Museums historical sites Shopping & restaurants Sample Data Small text with description, operating
hours Local map
August 24, 2006 Talk at SASTRA 28
How it works Info station
Island of wireless station Embedded in area Users have cheap low bandwidth components Integrated to network with high quality connection Requires some overlap to manage transition
between stations for hand off Scaleable by load balancing
Each center contains unique information Overhead of communication
Initialize externally specified; adjusts quickly
August 24, 2006 Talk at SASTRA 29
Map-on-the-move
Provide appropriate map County resolution driving in car Info stations small area high
bandwidth Remainder lower bandwidth
August 24, 2006 Talk at SASTRA 30
Problems in a Mobile Environment
Variable Bandwidth Disconnected Operation Limited Power Implications on distributed file
system support?
August 24, 2006 Talk at SASTRA 31
Constraints in mobile computing
PDA vs. Laptop vs. cell phones Cellular modem connection: Failure
prone Space: office vs. city vs. county Not continuous connectivity required Data such as pictures text files not
streaming audio and video Heterogeneous devices
August 24, 2006 Talk at SASTRA 32
MANET: Mobile Ad hoc Networks
A collection of wireless mobile nodes dynamically forming a network without any existing infrastructure and the relative position dictate communication links (dynamically changing).
From DARPA Website
August 24, 2006 Talk at SASTRA 33
Rapidly Deployable Networks
Failure of communication networks is a critical problem faced by first responders at a disaster site
major switches and routers serving the region often damaged cellular cell towers may survive, but suffer from traffic overload
and dependence on (damaged) wired infrastructure for backhaul In addition, existing networks even if they survive may
not be optimized for services needed at site significant increase in mobile phone traffic needs to be served first responders need access to data services (email, www,...) new requirements for peer-to-peer communication, sensor net or
robotic control at the site Motivates need for rapidly deployable networks that
meet both the above needs -> recent advances in wireless technology can be harnessed to provide significant new capabilities
August 24, 2006 Talk at SASTRA 34
Infostations Prototype: System for Rapid Deployment Applications
Outdoor Infostations with radio backhaul
for first responders to set up wireless communications infrastructure at a disaster site
provides WLAN services and access to cached data
wireless backhaul link includes data cache
Project for development of: high-speed short-range radios 802.11 MAC enhancements content caching algorithm &
software hardware integration including
solar panels, antennas and embedded computing device with WLAN card
WINLAB’s Outdoor Infostations Prototype (2002)
August 24, 2006 Talk at SASTRA 35
Ad-Hoc Wireless Network
PC-basedLinux routerPC
Router networkwith arbitrary topology
AP
Compute& storageservers
Managementstations
Radio Monitor
Forwarding Node/AP(custom)
Sensor Node(custom)
802.11bPDA
802.11bLinux PC
Commercial 802.11
A flexible, open-architecture ad-hoc WLAN and sensor network testbed ...
open-source Linux routers, AP’s and terminals (commercial hardware)
Linux and embedded OS forwarding and sensor nodes (custom) radio link and global network monitoring/visualization tools prototype ad-hoc discovery and routing protocols
August 24, 2006 Talk at SASTRA 36
What is a WSN?
A network that is formed when a set of small sensor devices that are deployed in an “ad hoc fashion” no predefined routes, cooperate for sensing a physical phenomenon.
A Wireless Sensor Network (WSN) consists of base stations and a number of wireless sensors.
Is simple, tiny, inexpensive, and battery-powered
Sensor: The device Observer: The end user/computer
Phenomenon: The entity of interest to the observer
August 24, 2006 Talk at SASTRA 37
Why Wireless Sensors Now?
Moore’s Law is making sufficient CPU performance available with low power requirements in a small size.
Research in Materials Science has resulted in novel sensing materials for many Chemical, Biological, and Physical sensing tasks.
Transceivers for wireless devices are becoming smaller, less expensive, and less power hungry (low power tiny Radio Chips).
Power source improvements in batteries, as well as passive power sources such as solar or vibration energy, are expanding application options.
August 24, 2006 Talk at SASTRA 38
Typical Sensor Node Features
A sensor node has: Sensing Material
Physical – Magnetic, Light, Sound Chemical – CO, Chemical Weapons Biological – Bacteria, Viruses, Proteins
Integrated Circuitry (VLSI) A-to-D converter from sensor to circuitry
Packaging for environmental safety Power Supply
Passive – Solar, Vibration Active – Battery power, RF Inductance
August 24, 2006 Talk at SASTRA 39
Portable and self-sustained (power, communication, intelligence). Capable of embedded complex data processing.
Transceiver
Embedded Processor
Sensor
Battery
Memory
Transceiver
Embedded Processor
Sensor
Battery
Memory
1Kbps- 1Mbps3m-300m
Lossy Transmission
8 bit, 10 MHzSlow Computation
Limited Lifetime
Requires Supervision
Multiple sensors
128Kb-1MbLimited Storage
Sensor Node Hardware
Sensor + Actuator + ADC + Microprocessor + Powering Unit + Communication Unit (RF Transceiver) + GPS
August 24, 2006 Talk at SASTRA 40
Sensors and Wireless Radio Types of sensors:
-Pressure,-Temperature-Light-Biological-Chemical-Strain, fatigue-Tilt
Capable to survive harsh environments (heat, humidity, corrosion, pollution etc).
No source of interference to systems being monitored and/or surrounding systems.
Could be deployed in large numbers.
August 24, 2006 Talk at SASTRA 41
ZigBee Wireless Communication Protocol
Based on the IEEE 802.15.4 standard
Small form factor Relatively Inexpensive Low Power Consumption Low Data Rate of Communication Self Organising, Self-Healing…
multi-hop nodes Integrated Sensors Ideal for Wireless Sensor Network
Applications
Wireless Sensor Networks
August 24, 2006 Talk at SASTRA 42
WSN APPLICATIONS
Potential for new intelligent applications: Smart Homes Process monitoring and control Security/Surveillance Environmental Monitoring Construction Medical/Healthcare
Implemented with Wireless Sensor Networks!
August 24, 2006 Talk at SASTRA 43
Medical and Healthcare Appln
Backbone Network
Backbone Network
Possibility for Remote consulting(including Audio Visual communication)
Net Switch
Wireless Remote consultation
Net Switch
Remote Databases
In HospitalPhysician
August 24, 2006 Talk at SASTRA 44
Medical and Healthcare Medical and Healthcare ApplicationsApplications
Sensors equipped Sensors equipped
with BlueToothwith BlueTooth
Source: USC Web Site
August 24, 2006 Talk at SASTRA 45
iBadge - UCLA
Investigate behavior of children/patient
Features: Speech recording / replaying Position detection Direction detection / estimation
(compass) Weather data: Temperature, Humidity,
Pressure, Light
August 24, 2006 Talk at SASTRA 46
Other Examples
MIT d'Arbeloff Lab – The ring sensor Monitors the physiological status of the
wearer and transmits the information to the medical professional over the Internet
Oak Ridge National Laboratory Nose-on-a-chip is a MEMS-based sensor It can detect 400 species of gases and
transmit a signal indicating the level to a central control station
VERICHIP: Miniaturised, Implanted, Identification Technology
August 24, 2006 Talk at SASTRA 47
Structural Health Monitoring
Semi-active Hydraulic Damper(SHD), Kajima Corporation, JapanModel bridge with attached wireless sensors,
B.F. Spencer’s Lab, Civil E., U. Illinois U-C
Accelerometer board prototype,Ruiz-Sandoval, Nagayama & Spencer,Civil E., U. Illinois Urbana-Champaign
August 24, 2006 Talk at SASTRA 48
Application in Environment Monitoring
Measuring pollutant concentration
Pass on information to monitoring station
Predict current location of pollutant volume based on various parameters
Take corrective action
Pollutants monitored by sensors in the river
Sensors report to the base monitoring station
ST
August 24, 2006 Talk at SASTRA 49
August 24, 2006 Talk at SASTRA 50
Vehicular Traffic Control
August 24, 2006 Talk at SASTRA 51
VMesh: Distributed Data Sensing, Relaying, & Computing via Vehicular Wireless Mesh Networks
US FCC allocated 5.850 to 5.925 GHz dedicated short range communication (DSRC)
Road side to Vehicle
Vehicle to vehicle communication
Project at The University of California, Davis
August 24, 2006 Talk at SASTRA 52
Network characteristics of WSN
Generally, the network: Consists of a large number of sensors (103 to
106) Spread over large geographical region
(radius = 1 to 103 km) Spaced out in 1, 2, or 3 dimensions Is self-organizing Uses wireless media May use intermediate “collators”
August 24, 2006 Talk at SASTRA 53
Sensor Network Topology Hundreds of nodes require careful handling of
topology maintenance. Predeployment and deployment phase
Numerous ways to deploy the sensors (mass, individual placement, dropping from plane..)
Postdeployment phase Factors are sensor nodes position change,
reachability due to jamming, noise, obstacles etc, available energy, malfunctioning, theft, sabotage
Redeployment of additional nodes phase Redeployment because of malfunctioning of units
August 24, 2006 Talk at SASTRA 54
Organization into Ad Hoc Net
Individual sensors are quite limited.
Full potential is realized only by using a
large number of sensors.
Sensors are then organized into an ad
hoc network.
Need efficient protocols to route and
manage data in this network.
August 24, 2006 Talk at SASTRA 55
Network Topologies
Star Single Hop Network All nodes communicate
directly with Gateway No router nodes Cannot self-heal Range 30-100m Consumes lowest power
August 24, 2006 Talk at SASTRA 56
Network Topologies
Mesh Multi-hopping network All nodes are routers Self-configuring network Node fails, network self-
heals Re-routes data through
shortest path Highly fault tolerant
network Multi-hopping provides
much longer range Higher power
consumption…nodes must always listen!
August 24, 2006 Talk at SASTRA 57
Network Topologies
Star-Mesh Hybrid Combines of star’s low
power and… …mesh’s self-healing
and longer range All endpoint sensor
nodes can communicate with multiple routers
Improves fault tolerance Increases network
communication range High degree of flexibility
and mobility
August 24, 2006 Talk at SASTRA 58
Self-Organizing WLAN Opportunistic ad-hoc wireless networking concepts starting to mature…
Initial use to extend WLAN range in user-deployed networks Based on novel auto-discovery and multi-hop routing protocols extends the utility and reach of low-cost/high speed WiFi equipment
Wired Network InfrastructureWired Network InfrastructureAP1 AP2
802.11 Access to AP
Ad-hoc radio link(w/multi-hop routing
Mobile Node (MN)(end-user)
Ad-hoc accessTo FN
Self-organizingAd-hoc WLAN
Forwarding Node (FN)
Forwarding Node (FN)
Ad-hocInfrastructure
links
August 24, 2006 Talk at SASTRA 59
How to get information from Data-centric Sensor Networks?
Types of Queries: Historical Queries: Analysis of data collected over time One Time Queries: Snapshot view of the network Persistent Queries: Periodic monitoring at long and regular
intervals Routing required to respond to a Query:
Application specific Data centric Data aggregation capability desirable Need to minimize energy consumption
August 24, 2006 Talk at SASTRA 60
Software Framework
MAC layer (Tiny OS, routing)
Configuration Table
Power consumption status & replacement strategy
Sensor Data Management
Middleware
Application (passing parameters via API)
August 24, 2006 Talk at SASTRA 61
Technical challenges
Sensor design Self-organizing network, that requires
0-configuration of sensors Random or planned deployment of
sensors, and collators Auto-addressing Auto-service discovery Sensor localization
August 24, 2006 Talk at SASTRA 62
Power Consumption
Limited Power Source
Battery Lifetime is limited
Each sensor node plays a dual role of data
originator and data router (data processor)
The malfunctioning of a few nodes consumes
lot of energy (rerouting of packets and
significant topological changes)
August 24, 2006 Talk at SASTRA 63
Environmental Factors
Wireless sensors need to operate in conditions that are not encountered by typical computing devices: Rain, sleet, snow, hail, etc. Wide temperature variations
May require separating sensor from electronics High humidity Saline or other corrosive substances High wind speeds
August 24, 2006 Talk at SASTRA 64
Historical ComparisonConsider a 40 Year Old Computer
Model Honeywell H-300 Mica 2
Date 6/1964 7/2003
CPU 2 MHz 4 MHz
Memory
32 KB 128 KB
SRAM ??? 512 KB
August 24, 2006 Talk at SASTRA 65
Advances in Wireless Sensor Nodes
Consider Multiple Generations of Berkeley Motes
Model Rene 2 Rene 2 Mica Mica 2
Date10/200
06/2001 2/2002 7/2003
CPU 4 MHz 8 MHz 4 MHz 4 MHz
Flash Memor
y8 KB 16 KB 128 KB 128 KB
SRAM 32 KB 32 KB 512 KB 512 KB
Radio10
Kbps10
Kbps40
Kbps40 Kbps
August 24, 2006 Talk at SASTRA 66
Summary Sensor networks will facilitate one to address
several societal issues: Early-warning systems Disaster mitigation
Applications in other sectors Security, transportation, irrigation
Technology is available today Research into new sensors Needs experimentation, pilot deployment Lots needs to be done in Software (OS, MAC, Application) While cost is an issue today, it will not be so tomorrow
August 24, 2006 Talk at SASTRA 67
References
Wireless & Mobile Systems Prof Dharma Prakash Agrawal and H. Deng
Integrating Wireless Technology in the Enterprise by Williams Wheeler, Elsevier Digital Press
Circuits & Systems for Wireless Communications Edited by Markus Helfenstein and George S. Moschytz, Kluwer Academic Publishers
August 24, 2006 Talk at SASTRA 68
Any Questions?