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Principles of Wireless Sensor Networks
www.kth.se/student/program-kurser/kurshemsidor/kurshemsidor/control/EL2745
Lecture 1 Stockholm, January 19, 2012
Carlo Fischione
Royal Institute of Technology - KTH Stockholm, Sweden e-mail: [email protected]
Course goal
After finishing the course, the attendants will know the essential control, networking and signal processing tools to cope with Wireless Sensor Networks (WSNs). They will understand the design issues of WSN and will be able to develop WSNs applications.
Systems and Control
Computer Networking
Wireless Communications
P
C Wireless Sensor Networks
Wireless Sensor Networks
Today’s lecture
§ Course overview
§ Introduction to WSNs
EL2745 Principles of Sensor Nets
§ Disposition
Ø 7.5 credits Ø 28 lectures, 28 exercises, 3 homework
§ Instructors
Ø Carlo Fischione, lecturer, [email protected]
Ø Euhanna Gadimi, teaching assistant, [email protected] Ø Yuzhe Xu, teaching assistant, [email protected]
Ø Hanna Holmqvist, administration, [email protected]
Course content
§ Part 1
Ø Lec 1: Introduction
Ø Lec 2: Programming
Ø Lec 3: Sensor modelling
Ø Lec 4: Physical layer
Ø Lec 5: Mac layer
Ø Lec 6: Routing
§ Part 2
Ø Lec 7: Estimation
Ø Lec 8: Detection
Ø Lec 9: Positioning and localization
Ø Lec 10: Time synchronization
§ Part 3
Ø Lec 11: Networked control systems 1
Ø Lec 12: Networked control systems 2
Ø Lec 13: Security
Ø Lec 14: Summary
Course material
§ Compendium: exercises sold at STEX § No book: lectures will be based on various chapters from
• G.J. Pottie and W.J. Kaiser, “Principles of Embedded Networked Systems Design” Cambridge, 2005
• W. Dargie and C. Poellabauer, “Fundamentals of Wireless Sensor Networks”, Wiley, 2010
• H. Karl and A. Willig, Protocols and Architectures for Wireless Sensor Networks, Wiley, 2005.
§ Lecture notes: handed out at lectures, available online
§ Homework: 3 exercises to hand in. First deadline, Feb 3
§ Software: Matlab and TinyOS
Useful links
http://www.wsnblog.com/ Blogs http://www.dustnetworks.com/
http://www.sensinode.com/ Industries http://www.sentilla.com/ http://www.xbow.com/Home/wHomePage.aspx http://www.hartcomm.org/ http://www.ieee802.org/15/pub/TG4.html
http://www.ietf.org/dyn/wg/charter/roll-charter.html WSNs Standard http://www.ipso-alliance.org/Pages/Front.php http://www.isa.org/ http://www.tinyos.net/ http://www.sics.se/contiki/ http://www.zigbee.org/ http://www.ee.kth.se/~mikaelj/wsn_course.shtml http://www.cs.berkeley.edu/~culler/eecs194/
http://bwrc.eecs.berkeley.edu/Research/energy_efficient_systems.htm University courses http://wsnl.stanford.edu/ http://courses.csail.mit.edu/6.885/spring06/readings.html http://www.eecs.harvard.edu/~mdw/course/cs263/fa04/ http://www.cs.sunysb.edu/~jgao/CSE595-spring09/
Practical Information
Office: Osquldas väg 10, floor 6. Office Times: Whenever you like, by appointment, send an e-mail. Prerequisites: The course is self-contained, familiarity with linear
algebra and analysis. Grades: based on homework (admission to exam) and exam.
Today’s lecture
§ Course Overview § Introduction to WSNs
Today’s learning outcome
§ What are the components of a WSN?
§ What are typical applications of a WSN?
§ What is a networking protocol?
§ How to design applications and protocols?
§ Wireless sensor networks (WSNs) make Internet of Things possible § Computing, transmitting and receiving nodes, wirelessly networked together
for communication, control, sensing and actuation purposes § Characteristics of WSNs
Ø Battery-operated nodes Ø Limited wireless communication Ø Mobility of nodes Ø No/limited central manager
WSNs
Typical power consumption of a node
DARPA DSN node, 1960 Mica2 mote, 2002
Tmote-sky mote, 2003 Smart Dust, 201?
History of WSNs
Application of WSNs
Marine monitoring
Transportation Industrial control
Economist
Health care
Environmental monitoring
Smart Buildings
WSNs to Control of temperature, light intensity, air and humidity.
Source: Ed Arens www.instablogsimages.com
Applications: Building Monitoring
§ Sensors used to measure response to traffic, tidal and seismic activity § Deployed on Golden Gate Bridge
Smart grids
§ Smart grids: “Smart Grids: It's All About Wireless Sensor Networks” (http://
stanford.wellsphere.com)
source: http://deviceace.com/
§ Added flexibility
Ø Sensor and actuator nodes can be placed more appropriately Ø Less restrictive maneuvers and control actions Ø More powerful control through distributed computations
§ Reduced installation and maintenance costs Ø Less cabling Ø More efficient monitoring and diagnosis
WSNs in Industrial Automation
Process Controller
Distributed Camera Calibration
• WSN allows one to perform distributed camera calibration • Application: massive graphic effects in film production
Participants in a WSN
§ Sources of data: Measure data, report them “somewhere” Ø Typically equip with different kinds of actual sensors
§ Sinks of data: Interested in receiving data from WSN
Ø May be part of the WSN or external entity, PDA, gateway, …
§ Actuators: Control some device based on data, usually also a sink
WSN node components
1. Controller 2. Communication device(s) 3. Sensors/actuators 4. Memory
5. Power supply
Memory
Controller Sensor(s)/ actuator(s)
Communication device
Power supply
Transceiver states
§ Transceivers can be put into different operational states, typically: Ø Transmit
Ø Receive Ø Idle – ready to receive, but not doing so
• Some functions in hardware can be switched off, reducing energy consumption a little
Ø Sleep – significant parts of the transceiver are switched off • Not able to immediately receive something • Recovery time and startup energy to leave sleep state can be
significant
Let’s now focus on the protocols followed at the communication device and the controller
Memory
Controller Sensor(s)/ actuator(s)
Communication device
Power supply
§ The behavior of a node is specified by a set of protocols, or set of rules with which the node operate.
§ Optimization and Parallel and Distributed Computation Theories are the essential mathematical tools to design WSNs
Protocol stack
Phy
MAC
Routing
Transport
Session
Application
Presentation
Cross-layer interaction
WSN Protocols
The radio power control problem
§ Let be a vector of radio powers Ø Each element of the vector is the radio power used for transmission
by a node § Let be the interference that the radio power has to
overcome so that the receiver can receiver successfully the transmitted information
§ Interference Function § The radio powers of every sensor must be minimized subject to
quality of communication constraints:
nodes
Tx
Rx
Phy MAC
Routing
Transport
Session
Application Presentation
Medium Access Control (MAC)
§ MAC: mechanism for controlling when to send a packet and when to
listen for a packet Ø MAC is one of the major component for energy expenditure. Ø Especially, idly waiting to receive packets wastes huge amounts of
energy
§ MAC is influenced by the transmit radio power
Phy MAC
Routing
Transport
Session
Application Presentation
Routing: how to choose paths
§ Maximum total available battery capacity Ø Path metric: Sum of battery
levels Ø Example: A-C-F-H
§ Minimum battery cost routing Ø Path metric: Sum of
reciprocal battery levels Ø Example: A-D-H
§ Conditional max-min battery capacity routing Ø Only take battery level into
account when below a given level
§ Minimum total transmission power
C 1
4 A
2 G
3 D
4 H
4 F
2 E
2 B
1
1
1
2
2
2 2
2
3
3
Phy MAC
Routing
Transport
Session
Application Presentation
§ The state of a process is sensed by wireless nodes § State information reaches the controller via multi-hop routing § How the protocols and the controller interact?
Control over WSNs
Process Controller
Phy MAC
Routing
Transport
Session
Application Presentation
§ We have seen the key aspects of WSNs Ø Applications
Ø Difference from other networks
Ø Nodes, protocols, and network architecture
§ Next Lecture, Monday 23: Olaf Landsiedel, “Introduction to WSN Programming”.
– You have to make some installations on your computer before the lecture
– See instructions on
www.kth.se/student/program-kurser/kurshemsidor/kurshemsidor/control/EL2745
Summary
