wireless senor network with zigbee a hand book

1. Wireless sensor networks
Dr. Narmada Alaparthi

2. 2
Wireless sensor networks
A sensor node (mote)
 8K RAM, 4Mhz processor
 magnetism, heat, sound, vibration, infrared
 wireless (radio broadcast) communication up to 100 feet
 costs ~$10 (right now costs $200)

3. 3
New Class of Computing
year
log(peoplepercomputer)
streaming
information
to/from physical
world
Number Crunching
Data Storage
productivity
interactive
Mainframe
Minicomputer
Workstation
PC
Laptop
PDA

4. 4
Why use a WSN?
• Ease of deployment
 Wireless communication means no need for a communication
infrastructure setup
 Drop and play
• Low-cost of deployment
 Nodes are built using off-the-shelf cheap components
• Fine grain monitoring
 Feasible to deploy nodes densely for fine grain monitoring

5. 5
Challenges in sensor networks
• Energy constraint
• Unreliable communication
• Unreliable sensors
• Ad hoc deployment
• Large scale networks
• Limited computation power
• Distributed execution
: Nodes are battery powered
: Radio broadcast, limited
bandwidth, bursty traffic
: False positives
: Pre-configuration inapplicable
: Algorithms should scale well
: Centralized algorithms
inapplicable
: Difficult to debug & get it right

6. 6
Outline
• Applications
• Platforms (hw&sw)
• WSN services (layers? what layers?)
• Comparison with the Internet architecture

7. 7
• Monitoring nesting behavior of birds
 Great Ducks experiment
• Detecting forest fires
• Detecting chemical or biological attacks
• Monitoring Redwood trees
Ecology monitoring

8. 8
Dense Self-Organized Multihop Network

9. 9R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R
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Temperature vs. Time
Temperature(C)
Humidity vs. Time
35
45
55
65
75
85
95
RelHumidity(%)
101 104 109 110 111
2003, unpublished
Bottom Top
36m
34m
30m
20m
10m

10. 10
Precision agriculture
• Wireless sensor networks can be placed on farm lands to
monitor temperature, humidity, fertilizer and pesticide levels
• Pesticide and fertilizer can only be applied when and where
required
 Pesticide and fertilizer per one acre costs $20
 Considering 100,000 acres savings of $2 million possible
Vineyards
BC

11. 11
Equipment Health Monitoring in
Semiconductor Fab
Fab Equipment
Mote + Vibration Sensors
Ad Hoc Mote
Network
Intranet
802.11 Mesh
Intranet isolation
Root Node
• Equipment failures in production fabs is very costly
 Predict and perform preemptive maintenance
• Typical fab has ~5,000 vibration sensors
 Pumps, scrubbers, …
 Electricians collect data by hand few times a year
 Sample: 10’s kilohertz, high precision, few seconds

12. 12
Put tripwires anywhere—in deserts, other areas where physical terrain
does not constrain troop or vehicle movement—to detect, classify &
track intruders
Project ExScal: Concept of
operation

13. 13
Envisioned ExScal customer application
Gas pipeline
Border control
Canopy precludes aerial
techniques
Rain forest – mountains – water
environmental challenges
Convoy protection
IED
Hide Site
Detect anomalous activity
along roadside

14. 14
ExScal summary
• Application has tight constraints of event detection scenarios: long
life but still low latency, high accuracy over large perimeter area
• Demonstrated in December 2004 in Florida
• Deployment area: 1,260m x 288m
• ~1000 XSMs, the largest WSN
• ~200 XSSs, the largest 802.11b ad hoc network

15. 15
Line in the sand project
• Thick line allows detection & classification as intruders enter the protected
region; also allows fine grain intruder localization
• Grid of thin lines allows bounded uncertainty tracking
Thick Entry Line
A S S E T
1 km
250 m

16. 16
ExScal sample scenarios
Intruding person walks through thick line
• (pir) detection, classification, and fine-grain localization
Intruding vehicle enters perimeter and crosses thick line
• (acoustic) detection, classification, and fine-grain localization
Person/ATV traverses through the lines
• coarse-grain tracking
Management operations to control signal chains, change parameters, and
programs dynamically; query status and execute commands

17. WSN Platforms:
Hardware & Software

18. 18
Types of sensor platforms
1. RFID equipped sensors
1. Smart-dust tags
 typically act as data-collectors or “trip-wires”
 limited processing and communications
• Mote/Stargate-scale nodes
• more flexible processing and communications
1. More powerful gateway nodes, potentially using wall power

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Grain-sized nodes
 Powered by inductive coupling to a transmission from a
reader device to transmit a message back
 Available commercially at very low prices
× Computation power is severely limited
× Can only trasmit stored unique id and variable
× Hard to add any interesting sensing capability

20. 20
Matchbox-sized nodes
• Mica series, XSM node, Telos
• 8-bit microprocessor, 4MHz CPU
 ATMEGA 128, ATMEL 8535, or Motorola HCS08
• ~4Kb RAM
 holds run-time state (values of the variables) of the program
• ~128Kb programmable Flash memory
 holds the application program
 Downloaded via a programmer-board or wirelessly
• Additional Flash memory storage space up to 512Kb.

21. 21
Mica2 and Mica2Dot
• ATmega128 CPU
– Self-programming
• Chipcon CC1000
– FSK
– Manchester encoding
– Tunable frequency
• Low power consumption
– 2 AA battery = 3V
1 inch

22. 22
Basic Sensor Board
• Light (Photo)
• Temperature
• Prototyping space for
new hardware designs

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Mica Sensor Board
• Light (Photo)
• Temperature
• Acceleration
– 2 axis
– Resolution: ±2mg
• Magnetometer
– Resolution: 134µG
• Microphone
• Tone Detector
• Sounder
– 4.5kHz

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Telos Platform
• Low Power
 Minimal port leakage
 Hardware isolation and buffering
• Robust
 Hardware flash write protection
 Integrated antenna (50m-125m)
 Standard IDC connectors
• Standards Based
 USB
 IEEE 802.15.4 (CC2420 radio)
• High Performance
 10kB RAM, 16-bit core, extensive double buffering
 12-bit ADC and DAC (200ksamples/sec)
 DMA transfers while CPU off

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Brick-sized node: Stargate
• Mini Linux computers communicating via 802.11 radios
 Computationally powerful
 High bandwidth
 Requires more energy (AA infeasible)
• Used as a gateway between the Internet and WSN

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Stargate

27. 27
Outline
• Hardware
 RFID, Spec
 Mica2, XSM, Telos
 Stargate
• Software
 TinyOS

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TinyOS
• most popular operating system for WSN
 developed by UC Berkeley
• features a component-based architecture
 software is written in modular pieces called components
 Each component denotes the interfaces that it provides
 An interface declares a set of functions called commands that the
interface provider implements and another set of functions called events
that the interface user should be ready to handle
• Easy to link components together by “wiring” their interfaces
to form larger components
 similar to using Lego blocks

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TinyOS
• provides a component library that includes network protocols,
services, and sensor drivers
• An application consists of
 a component written by the application developer and
 the library components that are used by the components in (1)
• An application developer writes only the application
component that describes the sensors used in the application,
the middleware services configured with the appropriate
parameters based on the needs of the application

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Benefits of using TinyOS
• Separation of concerns
 TinyOS provides a proper networking stack for wireless communication
that abstracts away the underlying problems and complexity of message
transfer from the application developer
 E.g., MAC layer
• Concurrency control
 TinyOS provides a scheduler that achieves efficient concurrency control
 An interrupt-driven execution model is needed to achieve a quick
response time for the events and capture the data
 For example, a message transmission may take up to 100msec, and without an
interrupt-driven approach the node would miss sensing and processing of
interesting data in this period
 Scheduler takes care of the intricacies of interrupt-driven execution and provides
concurrency in a safe manner by scheduling the execution in small threads.

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Benefits of TinyOS
• Modularity
 TinyOS’s component model facilitates reuse and reconfigurability since
software is written in small functional modules. Several middleware
services are available as well-documented components
 Over 500 research groups and companies are using TinyOS and
numerous groups are actively contributing code to the public domain

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RadioTimingSecDedEncode
The Complete Application
RadioCRCPacket
UART
UARTnoCRCPacket
ADC
phototemp
AMStandard
ClockC
bitbytepacket
SenseToRfm
HW
SW
IntToRfm
MicaHighSpeedRadioM
RandomLFSRSPIByteFIFO
SlavePin
noCRCPacket
Timer photo
ChannelMon
generic comm
CRCfilter

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TOS Execution Model
• commands request action
 ack/nack at every boundary
 call command or post task
• events notify occurrence
 HW interrupt at lowest level
 may signal events
 call commands
 post tasks
• tasks provide logical concurrency
 preempted by events
RFM
Radio byte
Radio Packet
bitbytepacket
event-driven bit-pump
event-driven byte-pump
event-driven packet-pump
message-event driven
active message
application comp
encode/decode
crc
data processing

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Event-Driven Sensor Access
Pattern
• clock event handler initiates data collection
• sensor signals data ready event
• data event handler calls output command
• device sleeps or handles other activity while waiting
• conservative send/ack at component boundary
command result_t StdControl.start() {
return call Timer.start(TIMER_REPEAT, 200);
}
event result_t Timer.fired() {
return call sensor.getData();
}
event result_t sensor.dataReady(uint16_t data) {
display(data)
return SUCCESS;
}
SENSE
Timer Photo LED

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Programming Syntax
• TinyOS 2.0 is written in an extension of C, called nesC
• Applications are too
 just additional components composed with OS components
• Provides syntax for TinyOS concurrency and storage model
 commands, events, tasks
 local frame variable
• Compositional support
 separation of definition and linkage
 robustness through narrow interfaces and reuse
 Interpositioning
• Whole system analysis and optimization

36. WSN Services:

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WSN services
• MAC protocols (BMAC, SMAC, TMAC, etc.)
• Topology control (GAF, SPAN, CEC, etc.)
• Clustering (Leach, FLOC, etc.)
• Time synchronization (Flooding time sync, reference broadcast)
• Localization (cricket, range-free techniques...)
• Routing (convergecast tree, geographic routing, hierarchical...)
• Querying (DSIB, DQT, directed diffusion, etc.)
• Tracking (Stalk, Trail, etc.)
• Network reprogramming

38. Comparison to
Internet architecture:

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Compared to Internet
• No clear layering; cross layer design is norm
• No separation between edge vs core of the network
 all nodes are both routers and hosts
• End-to-end principle fails
 unreliable channels, multihop latency
• Ad hoc deployment
 timesync, localization, topology control, clustering etc services needed
• Routing needs are different...