Wireless Sensor Networks

Rob Roosendaal, LecturerINHolland University

Agenda

Introduction Theoretical Background Practical Information Wrap up and questions

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Introduction to Wireless Sensor Networks

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Our projects

Alzheimer's disease ADL: Activities in Daily Life Acceptance of technologies How to measure progress in ADL Tablet as interface for easy acceptance Sensor technology for detection Sensor communication Collecting data

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Crawling the web

Alzheimer's disease Human computer interaction Programming Android tablets Connectiong devices to a tablet Wireless Sensor Networks

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Alzheimer's disease Memory loss that disrupts daily life Challenges in planning or solving problems Difficulty completing familiar tasks at home to work or at

leisure Confusion with time or place Trouble understanding visual images and special

relationships New problems with words in speaking or writing Misplacing things and loosing the ability to retrace steps Decreased and poor judgement Withdrawl from work or social activities Change in mood and peronality

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Framework for Disseminating Data

Establish communications message (What should be said?)

Define the audience (To whom should it be said?) Select the channel (Through what communication

medium?) Market the message (How should the message be

stated?) Evaluate the impact (What effect did the message

create?)

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Principles and Practice of Public Health Surveillance (Teutsch and Churchill, 2000)

Wireless Sensor Network

A wireless sensor network (WSN) of spatially distributed autonomous sensors to monitor physical or environmental conditions and to cooperatively pass their data through the network to a main location. The more modern networks are bi-directional, also enabling control of sensor activity.

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http://en.wikipedia.org/wiki/Wireless_sensor_network

Measuring physical parameters Acoustic, sound, vibration Automotive, transportation Chemical Electric current, electric potential, magnetic, radio Environment, weather, moisture, humidity Flow, fluid velocity Ionizing radiation, subatomic particles Navigation instruments Position, angle, displacement, distance, speed, acceleration Optical, light, imaging, photon Pressure Force, density, level Thermal, heat, temperature Proximity, presence Sensor technology Other sensors and sensor related properties and concepts

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This is only a summarized list, the complete list of sensors you can use is about 400 items long !

Measuring physical parameters Focusing on healthcare, domotics and personal

environment

Which sensors do we have?

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Points of interest

Autonomous sensors Physical or environmental conditions Cooperatively pass their data Through the network to a main location (Bi-directional, control of sensor activity)

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IT

Autonomous sensors

Sensing + Processing + Communication Prone to failure Energy drain Resource limitations:

– Memory, Power, Processing Sensor network architectures:

– Layered, Clustered

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Physical or environmental conditions

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Cooperatively pass their data

Receive or transmit Transmit if data has to be

sent Single-hop

– Close by– Lower transmission rate

Multi-hop– Higher transmission rate– Less nodes available

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Data-gathering wireless sensor networks: organization and capacity,Enrique J. Duarte-Melo, Mingyan Liu

Through the network to a main location Wireless and wired network parts Distributed routing, different routing protocols Adapting to changes in connectivity Real-time communication, connection

oriented! Quality of Service Security

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Structure/Backbone (HW)

Hardware aspects– basic aspects (CPU, memory, radio)– specific sensors aspects (what type of signals are

you measuring?)

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Structure/Backbone (SW)

Software aspects– Operating system– Network stack aspects

MAC layer aspects Network layer aspects Transport layer aspects Application aspects

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Structure/Backbone

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Equipment

Tablet, running the app Static computer for developing Wireless sensor network to gather data and

sent data to the tablet Wireless network for the tablet to comunicate

with the internet Server for monitoring the app (compressed

data)

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Wireless Sensor Node (1)

Sensor nodes1. sensor technology 2. tiny battery driven computers 3. wireless communication interface4. organize into a network 5. monitoring of processes, environmental conditions,

events6. act as routers 7. forward data cooperatively

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Wireless Sensor Node (2)rroosend@xs4

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Wireless Sensor Node (3)rroosend@xs4

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Classifications of sensor network protocols

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Clustered sensor network architecture Organizes the sensor nodes into clusters Each cluster is governed by a cluster-head Only heads send messages to a BS Suitable for data fusion Self-organizing

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Layered sensor network architecture Short-distance, low power Unified Network Protocol

Framework (UNPF) Integrates three operations:

– Network Initialization & Maintenance Protocol

– MAC Protocol– Routing Protocol

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Network Initialization & Maintenance Protocol Base Station (BS) broadcasts ID using Code Division

Multiple Access (CDMA) common control channel (BS reaches all nodes in one hop)

Nodes record BS ID & send beacon signal with their own IDs at their low default power levels

All nodes the BS can hear are at 1-hop distance The BS broadcasts a control packet with all layer one

node IDs All nodes send a beacon signal again The layer one nodes record the IDs they hear-layer 2 The layer one nodes inform the BS of the layer 2 The BS broadcasts the layer2 nodes IDs,… To maintain: periodic beaconing updates are required

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Routing Protocol

Downlink from the BS is by direct broadcast on the control channel

Enables multi-hop data forwarding to the BS

The remaining energy is considered when forwarding to the next hop (layer)

Only the nodes of the next layer need to be maintained in the routing table

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Low-Energy Adaptive Clustering Hierarchy (LEACH) Self-organizing and adaptive clustering

protocol Evenly distributes the energy expenditure

among the sensors Performs data aggregation where cluster

heads act as aggregation points Two main phases:

– Setup phase: organizing the clusters– Steady-state phase: deals with the actual data

transfers to the BS

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Low-Energy Adaptive Clustering Hierarchy (LEACH)

Merits:– Accounting for adaptive clusters and

rotating cluster heads– Opportunity to implement any

aggregation function at the cluster heads

Demerits:– Highly dynamic environments– Continuous updates– Mobility

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Efficient Data Gathering in WSN Data gathering from different correlated

– cues from the network stateuses hints or cues about the physical environment to optimize network behavior

– energy-efficient rooted aggregation treesa simple, scalable and distributed correlation-aware aggregation structure

– congestion reduction techniquesproviding congestion control from the sink to the sensors in a sensor field

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Medium Access Control

Framing– Frame format and data en- and decapsulation

Medium Access – Which devices participate in communication at what

time Reliability

– Successful transmission between devices Flow Control

– Prevent frame loss through buffer overloads Error Control

– Error detection or correction

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Location discovery?

Distance estimation– Techniques to estimate the relative distance between

nodes Position computation

– Calculate coordinates based on known other nodes– Triangulation, multilateration, proximity

Localization– Based on information about distances and positions

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Leftovers

Quality of network coverage Security Real time communication ...

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Conclusion

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The internet of things is close!

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What we can do:– Acquired data– Reports or alarm notices – Automatically forwarded to

information systems

What we can do with this technology:– Extending the internet into the

real-world– Autonomous Information Systems

Automatically update themselves Synchronize with the actual state of

monitored structure or process

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The internet of things is close!

What we can do with this technology:– Near-real-time information

enables early intervention Prevent abnormal behavior Malfunction Damages Dangerous situations

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The internet of things is close!

Typical application domains:– Home care and e-health (or t-

health)– Environmental monitoring – Factory automation and

maintenance– Supply chain and asset

management – Physical security and control– …

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The internet of things is close!

Practical Information

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Wireless Sensor Network

Coalesenses– Wireless Sensor Technology– Wireless Sensor Modules– Wireless Sensor Solutions– Solar Power Harvesting– Wireless Sensor Devices– ...

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http://www.coalesenses.com/

Wireless Sensor Modules

The iSense modular hardware and software platform for wireless networks for industry and research applications comprises modules for wireless networking, sensors modules, different power supplies, solar power harvesting, interfaces to PCs, GPS and more.

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Wireless Sensor Solutions

Based upon a broad range of hardware, software and protocol components as well as our different networking devices, coalesenses offersboth standardized as well as customer specific wireless sensor networking systems.

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Solar Power Harvesting

The iSense Solar Power Harvesting System is an out-of-the-box solution for running self-powered wireless sensor networks. By harvesting solar energy and storing it in a rechargeable battery, it allows to operate sensor nodes all-time autonomously

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Wireless Sensor Devices

coalesenses offers a number of different devices as building blocks for wireless systems, ranging from LAN gateways over repeaters to USB sticks.

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Wireless Sensor Technologycoalesenses offers a collection of hardware and software for wireless sensor networks, a technology for literally giving eyes and ears to modern control and information systems.

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Wrapup and Questions

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Wrap up

Environment: – Health, Alzheimers– Domotics, Wireless Sensor Networks– IT, Tablet and internet connection

Main question:– How can we add value to the life of a patient with

Alzheimers

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What is next?rroosend@xs4

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Questionsrroosend@xs4

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