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

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

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

802.11 Ad hoc Mode IEEE 802.11 already provides support for ad hoc mode Computers can be connected without an access point Only work with single hop

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

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

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

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

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

Traditional Sensors sensor field Network Remote monitoring Data loggers Local monitoring

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

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

Demonstration

Sensor Modules IWING-MRF modules from IWING LAB 250 kbps 2.4GHz IEEE 802.15.4 12MHz Atmel ATMega328P microcontroller Sensors: Light, Temperature, Acceleration

Scenario Monitor station Sensor nodes measuring physical environment

WSN Platforms Most are based on IEEE 802.15.4 (Wireless Low-Rate Personal Area Network) and many others…

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 802.15.4 (~370 THB) ESP8266 Wi-Fi Module 2.4 GHz IEEE 802.11 b/g/n (~150 THB)

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

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

Internet of Things (IoT) http://www.opinno.com/en/content/internet-things-0

Connected Living NTT DoCoMo, Japan http://www.dezeen.com/2013/09/11/nismo-smartwatch/

Landslide Monitor Real deployment scenario…

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

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

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

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

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

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

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?

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

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

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

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

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

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

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

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, …)

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