1. Protocols and Applications for Wireless Sensor Networks (01204525) Ad hoc and Sensor Networks
Chaiporn Jaikaeo
Department of Computer Engineering Kasetsart University
Materials taken from lecture slides by Karl and Willig

2. Typical Wireless Networks
Base stations connected to wired backbone
Mobile nodes communicate wirelessly to base stations

3. Ad hoc Networks
Networks without pre-configured infrastructure
require no hubs, access points, base stations
are instantly deployable
can be wired or wireless
Initially targeted for military and emergency applications
wired
wireless
multi-hop wireless
In the last few decades, the Internet has been growing very quickly. People can communicate with each other thru it.
There are situations where the Internet is not available. -> Ad hoc networks
As oppose to the Internet and cellular networks, there is no fixed infrastructure

4. Ad hoc Mode
IEEE already provides support for ad hoc mode
Computers can be connected without an access point
Only work with single hop

5. Possible Applications for Ad hoc Networks
Factory Floor Automation
Disaster recovery
Car-to-car communication

6. Problems/Challenges for Ad hoc Networks
Lack of central entity for organization available
Limited range of wireless communication
Mobility of participants
Battery-operated entities

7. Self-Organization
Without a central entity, nodes must organize themselves into a network
Examples:
Medium access control
Finding a route

8. Characteristics of Ad hoc Networks
Heterogeneity ― sensors, PDAs, laptops
Limited resources ― CPU, bandwidth, power
Dynamic topology due to mobility and/or failure
Mobile Ad hoc Networks (MANETs) B C A

9. Sensor Networks
Participants in the previous examples were devices close to a human user, interacting with humans
Alternative concept:
Instead of focusing interaction on humans, focus on interacting with environment
Network is embedded in environment
Nodes in the network are equipped with sensing and actuation to measure/influence environment
Nodes process information and communicate

10. Traditional Sensors sensor field Network Remote monitoring
Data loggers
Local monitoring

11. Wireless Sensors Sensors communicate with data logger via radio links
Network
Remote monitoring
sensor field
radio link

12. Wireless Sensor Networks
Wireless sensors + wireless network
Sensor nodes (motes) deployed and forming an ad hoc network
Requires no hubs, access points
Instantly deployable
Targeted applications
Emergency responses
Remote data acquisition
Sensor node/mote
Internet
Gateway
Remote monitoring
Sensor network

13. Demonstration

14. Sensor Modules IWING-MRF modules from IWING LAB
250 kbps 2.4GHz IEEE
12MHz Atmel ATMega328P microcontroller
Sensors: Light, Temperature, Acceleration

15. Scenario
Monitor station
Sensor nodes measuring physical environment

16. WSN Platforms
Most are based on IEEE (Wireless Low-Rate Personal Area Network)
and many others…

17. Future Trends
Many low-cost, wireless modules and SoC (System on Chip) already available
NXP's JN5168 Module
32-bit RISC CPU, 32K RAM
2.4 GHz IEEE
(~370 THB)
ESP8266 Wi-Fi Module
2.4 GHz IEEE b/g/n
(~150 THB)

18. WSN Application Examples
Agriculture
Humidity/temperature monitoring
Civil engineering
Structural response
Disaster management
Environmental sciences
Habitat monitoring
Conservation biology

19. WSN in Telemetry Applications
Browser
sensor
sensor
GPRS Network or Internet
Information Server
wireless sensor node
Gateway
Sensor field

20. Internet of Things (IoT)

21. Connected Living NTT DoCoMo, Japan

22. Landslide Monitor
Real deployment scenario…

23. WSN Application Scenarios
Facility management
Intrusion detection into industrial sites
Control of leakages in chemical plants, …
Machine surveillance and preventive maintenance
Embed sensing/control functions into places no cable has gone before
E.g., tire pressure monitoring
Precision agriculture
Bring out fertilizer/pesticides/irrigation only where needed
Medicine and health care
Post-operative or intensive care
Long-term surveillance of chronically ill patients or the elderly

24. WSN Application Scenarios
Logistics
Equip goods (parcels, containers) with a sensor node
Track their whereabouts – total asset management
Note: passive readout might suffice – compare RF IDs
Telematics
Provide better traffic control by obtaining finer-grained information about traffic conditions
Intelligent roadside
Cars as the sensor nodes

25. 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 (actors): Control some device based on data, usually also a sink
WSN = WASN

26. Classifying Application Types
Interaction patterns between sources and sinks classify application types
Event detection
Periodic measurement
Function approximation
Edge detection
Tracking

27. Deployment Options Dropped from aircraft Well planned, fixed
Random deployment
Well planned, fixed
Regular deployment
Mobile sensor nodes
Can move to compensate for deployment shortcomings
Can be passively moved around by some external force (wind, water)
Can actively seek out “interesting” areas

28. Maintenance Options
Feasible and/or practical to maintain sensor nodes?
Replace batteries
Unattended operation
Impossible but not relevant
Energy supply
Limited from point of deployment
Some form of recharging / energy scavenging

29. Characteristic Requirements
Type of service of WSN
Not simply moving bits like another network
Rather: provide answers (not just numbers)
Geographic scoping are natural requirements
Quality of service
Fault tolerance
Lifetime: node/network
Scalability
Wide range of densities
Programmability
Maintainability
Definition of network lifetime as a homework?

30. Required Mechanisms Multi-hop wireless communication
Energy-efficient operation
Both for communication and computation, sensing, actuating
Auto-configuration
Manual configuration just not an option
Collaboration & in-network processing
Nodes in the network collaborate towards a joint goal
Pre-processing data in network (as opposed to at the edge) can greatly improve efficiency

31. Required Mechanisms Data centric networking Locality Exploit tradeoffs
Focusing network design on data, not on node identifies (id-centric networking)
To improve efficiency
Locality
Do things locally (on node or among nearby neighbors) as much as possible
Exploit tradeoffs
E.g., between invested energy and accuracy

32. MANET vs. WSN - Similarities
MANET – Mobile Ad hoc Network
Self-organization
Energy efficiency
(Often) Wireless multi-hop

33. MANET vs. WSN - Differences
Equipment: MANETs more powerful
Application-specific: WSNs depend much stronger on application specifics
Environment interaction: core of WSN, absent in MANET
Scale: WSN might be much larger (although contestable)
Energy: WSN tighter requirements, maintenance issues

34. MANET vs. WSN - Differences
Dependability/QoS: in WSN, individual node may be dispensable (network matters), QoS different because of different applications
Addressing: Data centric vs. id-centric networking

35. Wireless Fieldbuses Fieldbus:
Network type invented for real-time communication, e.g., for factory-floor automation
Inherent notion of sensing/measuring and controlling
Wireless fieldbus: Real-time communication over wireless

36. Wireless Fieldbuses vs. WSNs
Scale – WSN often intended for larger scale
Real-time – WSN usually not intended to provide (hard) real-time guarantees as attempted by fieldbuses

37. Enabling Technologies for WSN
Cost reduction
For wireless communication, simple microcontroller, system on chip, sensing, batteries
Miniaturization
Some applications demand small size
“Smart dust” as the most extreme vision
Energy scavenging
Recharge batteries from ambient energy (light, vibration, …)

38. Conclusion
MANETs and WSNs are challenging and promising system concepts
Many similarities, many differences
Both require new types of architectures & protocols compared to “traditional” wired/wireless networks
In particular, application-specificness is a new issue