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Development and Evaluation of Energy-Efficient and Adaptive Protocolsfor Wireless Sensor Networks
1. IEEE 3rd Latin-American Conference on
Communications – LATINCOM 2011
Development and Evaluation of
Energy-Efficient and Adaptive Protocols
for Wireless Sensor Networks
Torsten Braun, Universität Bern, Switzerland
braun@iam.unibe.ch, rvs.unibe.ch
joint work with many other persons, see publications
2. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Overview
> Introduction
— Wireless Sensor Network Applications and Application Requirements
— Design, Implementation, Evaluation of WSN Protocols
> Experimentation Platform for WSN Research
— Wireless Sensor Network Testbed
— Software-Based Estimation of Energy Consumption
> WSN Research Experiments
— Traffic-Adaptive and Energy-Efficient WSN MAC Protocol
— Adaptive Forward Error Control in WSNs
> Conclusions
> Outlook: Mobility Support
Belém, October 24, 2011 2
3. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Wireless Sensor Network Applications
> REDE (REde de sensores sem fio
para Detectar Enchentes) project
(USP São Carlos,
http://sp-river.blogspot.com)
> Outdoor deployment of wireless
sensor network to measure water
depth and pollution in creeks of
the city of São Carlos SP
> SunSPOT motes and hydrostatic
level and conductivity sensors.
Jó Ueyama, Daniel Roy Hughes, Nelson Matthys,
Wouter Horré, Wouter Joosen, Christophe Huygens,
Sam Michiels:
An Event-based Component Model for Wireless
Sensor Networks: a Case Study for River Monitoring,
XXVIII Simpósio Brasileiro de Redes de
Computadores e Sistemas Distribuídos
Belém, October 24, 2011 3
4. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Wireless Sensor Network Applications
> Environmental monitoring (A4-Mesh, a4-mesh.unibe.ch)
Thomas Staub, Benjamin
Nyffenegger, Desislava Dimitrova,
Torsten Braun:
Operational Support of Wireless
Mesh Networks Deployed for
Extending Network Connectivity,
1st International Workshop on
Opportunistic Sensing and
Processing in Mobile Wireless
Sensor and Cellular networks
(MobiSense), Bilbao, May 2011
Belém, October 24, 2011 4
5. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
A4-Mesh Impressions
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6. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Wireless Sensor Network Applications
> Monitoring and control of buildings using sensor nodes and
artificial neural networks
Markus Wälchli, Torsten Braun:
Building Intrusion Detection with a
Wireless Sensor Network, ICST
AdHocNets, Niagara Falls, 2009
Belém, October 24, 2011 6
7. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Application Requirements
> Energy-efficient operation
> Low delays
> Reliability
> Adaptivity to varying link characteristics and traffic load
Belém, October 24, 2011 7
8. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Design, Implementation, and Evaluation
of Wireless Sensor Network Protocols
> Simulations are only meaningful with accurate calibration of
parameters, e.g., energy consumption, transmission
characteristics, traffic models.
> Experiments in testbeds give insights about protocol behaviour
in more realistic scenarios and system-related issues,
but face several problems
— Experiment control
— Scalability
— Reproducability
— Energy measurements
— Mobility
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10. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Wireless Sensor Network Testbed
(WISEBED)
> Recently finished FP7 Future Internet
research project
> wisebed.eu
> Pan-European federation of
9 WSN testbeds Testbed
Testbed
Testbed
> approx. 1000 deployed nodes
> Each partner runs own testbed
with different hardware. Testbed
> Use of individual testbed or
interconnected testbeds Testbed
Testbed
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11. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
General Testbed Infrastructure
> Portal WSN
Testbed
— Gateway between Internet and WSN part of
Internet WISEBED
— Used for WSN management
> Wireless Sensor Network
— Sensor nodes communicate with
each other. Portal
— Backbone used to communicate with DB
portal. WSN
Backbone Testbed
> Internet part of
WISEBED
— connects all WISEBED testbeds Wireless
Sensor Network
(WSN)
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12. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Testbed @ Universität Bern
Mesh Node
Internet
USB
Ethernet
LAN
wireless
Portal
(running TARWIS
management system)
Sensor Node
Belém, October 24, 2011
12
13. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Testbed @ Universität Bern
> Approx. 50 TelosB/MSB430 nodes connected to
portal via Ethernet with temperature, humidity, light
sensors
Belém, October 24, 2011 13
14. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
TARWIS System Architecture
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15. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Testbed / Sensor Node Reservation
> Reservation system maintains per-site reservation database.
> User Interfaces
— Web-based user interface
— iPhone application
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16. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
TARWIS Experiment Configuration
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17. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
TARWIS Experiment Monitoring
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18. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
TARIWS-Generated Experiment Trace
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20. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Software-Based Estimation of
Energy Consumption
> Problem:
Equipment of sensor nodes with measurement hardware is
— very expensive.
— difficult in out-door environments / real-world deployments.
— not sufficient to support energy awareness.
– Energy awareness: Application / system adapts operation in order
to meet energy consumption constraints.
> Solution:
Software-based energy measurement
(calibration of software-based model using measurement
hardware)
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21. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Hardware-Based Energy Measurements
> Measurement of current draw and voltage using
Sensor Network Management Devices (SNMD) from KIT
Belém, October 24, 2011 21
22. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Simple 3-State-Model
A. Dunkels, F. Osterlind, N. Tsiftes, Z. He: Software-based On-line Energy Estimation for Sensor Nodes. IEEE EmNets, 2007
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23. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Measured vs. Estimated Energy Consumption
Approach: Measurement of current draw in different states and energy estimation by
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24. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
3-State-Model with State Transitions
Revised estimation:
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25. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Estimation Accuracy
OLS: Ordinary Least Squares Regression Analysis
On the Accuracy of Software-based Energy Estimation Techniques. Philipp Hurni, Torsten Braun, Benjamin Nyffenegger,
Anton Hergenroeder: 8th European Conference on Wireless Sensor Networks (EWSN), Bonn, Germany, February 2011.
Belém, October 24, 2011 25
27. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
MAC Protocols for Wireless Sensor Networks
1. Scheduled Protocols
— Multiplexing and Allocation of channels, e.g., time multiplexing,
requires accurate time synchronization
2. Contention-based Protocols
— Channel sharing and allocation on-demand, often: periodic wake-ups
— Problems: collisions and delays
— Sender must ensure that receiver is awake during transmission
– Transmissions of long preambles/beacons (B-MAC, X-MAC, WiseMAC)
– Weakly synchronized wakeups (S-MAC, T-MAC)
– Receiver signals wakeup (RI-MAC)
— Load adaptation
– Adaptation of wakeup time dependent on activation events or load
(T-MAC, X-MAC)
Wake-up interval
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28. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
WiseMAC
> Very energy-efficient MAC protocol, but adaptivity to traffic
variation is very limited.
> Unsynchronized nodes wakeup for a short time
> Tpreamble = min {4θL,T}
— θ: clock drift, L: time since last update, T: duration of a cycle
— Max. clock drift: 2θL, sender must start preamble transmission 2θL
prior to wakeup and transmit it until 2θL after wakeup.
> „Piggybacking― of wakeup times
Enz et al.: WiseNET: An Ultralow-Power Wireless Sensor Network
Solution, IEEE Computer, Vol. 37, No. 8; August 2004
Belém, October 24, 2011 28
29. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
MaxMAC: a Maximally Traffic-Adaptive
and Energy-Efficient WSN MAC Protocol
> is based on sampling of preambles, cf. WiseMAC
> integrates destination address into preamble to reduce overhearing
> Additional wakeups for higher rates of received packets
(measurement by sliding window)
— Periodic reports in acknowledgements from receiver to sender
— State transitions if thresholds T1,T2,TCSMA are exceeded.
packet rate ≥ T1 packet rate ≥ T2 packet rate ≥ TCSMA
S1 S2
Base CSMA
2* 4*
state duty duty
RECV
cycle cycle
packet rate < T1 packet rate < T2 packet rate < TCSMA
Lease expired Lease expired Lease expired
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30. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
MaxMAC
CSMA
Philipp Hurni and Torsten Braun. MaxMAC: a maximally traffic-adaptive MAC protocol for wireless sensor networks.
7th European Conference on Wireless Sensor Networks (EWSN), Coimbra, Portugal, February 2010.
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31. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
MaxMAC Implementation on MSB430
> Threshold parameters: T1 = 1, T2 = 2, TCSMA = 3 packets / s
> Base duty cycle: 0.6 % (3 ms) for a base interval of 500 ms
> Frame size: 40 bytes including header
> Lease times: 3 s
> Bit rate: 19.2 kbps
> Implementation of packet burst mode
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32. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Implementation Experiences
Implementation of MaxMAC on MSB430 using Scatterweb
operating system raised several problems:
> Inaccurate execution of timers,
e.g., because of active event processing at timer expiration
→ somewhat earlier scheduling of timers
> Overhearing avoidance has not been supported by node
hardware.
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33. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Experiments with Intruder Scenario I
WiseMAC
MaxMAC
CSMA
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34. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Experiments with Intruder Scenario II
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36. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Error Control in Wireless Sensor Networks
> Wireless channels in sensor networks have varying bit error
rates, sometimes up to 20 %.
> Options
— Automatic Repeat Request (ARQ)
– Retransmission adds delay.
– Original transmission was useless, but consumed bandwidth and
energy.
— Forward Error Correction (FEC)
– Relatively small delay (due to encoding and decoding) compared to
ARQ for error correction
– En-/decoding can be costly (several 100 ms for decoding).
– Too strong codes consume computing resources and bandwidth.
– Too weak codes might not be able to correct errors.
> Proposed Approach: Adaptive FEC
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37. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Implementation of FEC Library
> Repetition Code
> Hamming Code
> Double Error Correction Triple Error Detection (DECTED)
> Bose-Chaudhuri-Hocquengham (BCH)
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38. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Adaptive FEC
> Stateful Adaptive FEC (SA)
— Selection of current code dependent on success of previous
transmission (next higher / lower level)
— Quick adaptation
> Stateful History Adaptive (SHA)
— History of last transmissions (here: 5)
— For successful/failed transmissions: storage of next lower/higher level
— Selection of level with majority in history
— Reacts less quickly than SA-FEC
Philipp Hurni, Sebastian Barhlomé,
> Stateful Sender Receiver Adaptive (SSRA) Torsten Braun:
— Consideration of number of corrected bit errors Link-Quality Aware Run-Time
Adaptive Forward Error Correction
by receiver (to be reported in acknowledgement) Strategies in Wireless Sensor
Networks, submitted
(63,36)
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39. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Energy Consumption by FEC and ARQ
> Additional power consumption by FEC
> In case of no FEC, MSB430 node can enter lower power mode
with Idefault
> Energy for encoding/decoding 32 bytes (30/100 ms): 0.95 mJ
> Energy for retransmission
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40. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Wisebed Experiments
> Different link characteristics → Deployment of a single FEC
scheme would not be most efficient.
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41. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Static vs. Adaptive FEC
> Better error correction performance of
adaptive FEC schemes than for static ones.
> Adaptive FEC advantages
— Lower processing and energy costs
— Lower bandwidth and lower interference
in multi-hop scenarios
— Higher packet delivery rate
— Adapt automatically to different
link characteristics
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42. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Conclusions
> Contributions
— Design and experimental evaluation of energy-efficient, reliable, and
adaptive protocols
> Experiences: Development and use of WSN testbed resulted in
— More efficient use of hardware resources
— Testbed experiments as easy as simulations
— Repeatability and larger number of experiments
(statistical significance)
— Reproducability of experiments and results
> Outlook
— Several experiences (testbeds, protocols) to be applied in other
areas, e.g. wireless mesh and ad-hoc networks
— Mobility support in wireless sensor / mesh network testbeds
Belém, October 24, 2011 42
43. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Wireless Sensor Networks and UAVs in
Agriculture
Field not to be sprayed
Sensor-UAV-link
UAV-UAV-link Fausto Guzzo da Costa, Torsten
Braun, Jó Ueyama, Gustavo Pessin,
Fernando Santos:Arquitetura baseada
chemicals em veículos aéreos não tripulados e
redes de sensores sem fio para
Field to be sprayed aplicações agrícolas, VIII Congresso
Brasileiro de Agroinformatica,
Belém, October 24, 2011 SBIAGRO 2011, Bento Gonçalves 43
44. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
VirtualMesh:
Wireless and Mobile Network Emulation
Thomas Staub, Reto Gantenbein, Torsten Braun:
VirtualMesh: an emulation framework for wireless
mesh and ad hoc networks in OMNeT++,
SIMULATION: Transaction of the Society for
Modelling and Simulation International, Vol. 87,
No. 1-2, January 1, 2011
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45. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Mobility Support in Wisebed by VirtualMesh
Torsten Braun, Geoff Coulson, Thomas Staub: Towards Virtual Mobility Support in a Federated Testbed for Wireless Sensor
Networks, 6th Workshop on Wireless and Mobile Ad-Hoc Networks (WMAN 2011), Kiel, Germany, March 10 - 11, 2011
Belém, October 24, 2011 45
46. Torsten Braun: Development and Evaluation of Energy-Efficient and Adaptive Protocols for Wireless Sensor Networks
Thanks for your attention !
> Contact: braun@iam.unibe.ch
> More information: rvs.unibe.ch
Belém, October 24, 2011 46