On Demand Time Sychronizaton for Wireless Sensor Networks-november2009
-
Upload
abhiumn -
Category
Technology
-
view
344 -
download
0
description
Transcript of On Demand Time Sychronizaton for Wireless Sensor Networks-november2009
![Page 1: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/1.jpg)
On-demand Time Synchronization for Wireless Sensor Networks
[Plan B project]
Advised by: Prof. Tian He
Presented by:
Abhishek Rawat
![Page 2: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/2.jpg)
Introduction
Time synchronization middleware service provides time-reference for nodes
Time reference Global Peer-node
![Page 3: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/3.jpg)
Introduction: applications
Example Applications Sniper detection Seismic activity detection Structural monitoring Object tracking Habitat Monitoring
![Page 4: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/4.jpg)
Introduction: services
Provide time-reference for some sensor node functions TDMA scheduling LPL communication Distributed processing Aggregation techniques
![Page 5: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/5.jpg)
Time Synchronization: approaches Proactive techniques
periodically synchronize the nodes periodicity based on precision requirement
Reactive techniques
Actuated by the event
Periodicity based on event frequency
![Page 6: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/6.jpg)
Existing Techniques
Several techniques application in post and pre-event scenarios Varying accuracy and communication cost
Notable techniques RB TPSN FTSP ETA
![Page 7: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/7.jpg)
Existing Techniques [continued] RBS
Receiver- receiver Broadcast based
TPSN Sender-sender MAC time-stamping
![Page 8: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/8.jpg)
Existing Techniques [continued] FTSP
Broadcast-based MAC time-stamping and skew calculation High accuracy Reactive technique Hardware calibration
![Page 9: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/9.jpg)
Existing Techniques
ETA State-of-art Elapsed Time-of-Arrival primitive Reduced communication cost Elapsed time in data-item-no separate time-
synchronization messaging Skew calculation is a problem
![Page 10: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/10.jpg)
Problem Statement
How to minimize the cost of time-synchronization? Optimizing communication requirement with
desired accuracy
![Page 11: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/11.jpg)
Motivation
Reducing communication cost post-facto technique caching: time-reference present in network
![Page 12: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/12.jpg)
Assumptions
Spatiotemporal events Adjacent nodes will detect the event Time reference would be available in mearby
nodes Unicast messaging will reduce communication
cost
![Page 13: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/13.jpg)
Sources of Error
Time-reference communication Sources of delay in timestamp delivery
Send/Receive Time Access Time Transmission and Reception Time Propagation Time Interrupt Handling Encoding/Decoding Time Byte Alignment Hardware Calibration/Clock-Skew
![Page 14: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/14.jpg)
Proposed Approach
On-demand Time Synchronization Protocol
Post-facto approach
Primitive: seeker provider determination post-event
Time-reference exchange using 3-way handshake
Clock offset and Clock skew rate calculation
![Page 15: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/15.jpg)
Approach Details
Seeker Determination
Data > threshold value
Previous time reference : Expired !!!
![Page 16: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/16.jpg)
Approach Details
Provider determination
![Page 17: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/17.jpg)
Approach Details: time reference exchange Time-Synchronization Messaging
3-way handshake
Tx2Tx1initMsg
t1
provider-node
t0
t2 t5
t4t3
seeker-node
Fig2. Messages exchanged during time-synchronization between two nodes
![Page 18: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/18.jpg)
Approach Details [continued]
Skew Calculation
![Page 19: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/19.jpg)
Approach Details [continued]
Offset Calculation
![Page 20: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/20.jpg)
Implementation: platform
Platform
Simulator
![Page 21: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/21.jpg)
Implementation: system design Modules:
TimeLibService TimeSyncModule TimeSyncCtrl TimeSyncCommModule Routing Module SenseDB
![Page 22: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/22.jpg)
Implementation: system design [continued] Diagram
![Page 23: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/23.jpg)
Analysis: applications
Accuracy requirement
Habitat monitoring : order of seconds Seismic activity detection : order of 10 milliseconds Sniper detection : order of 1 millisecond Structural monitoring : order of 10 milliseconds
![Page 24: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/24.jpg)
Results
Data Analysis for Real Time Experiment Seismic activity detection
Data Analysis from TOSSIM based simulations Error- analysis Communication cost with event frequency Communication cost with event density Delivery success rate
![Page 25: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/25.jpg)
Results: Data Analysis for Real Time Experiment
Analysis of Data from Seismic Activity Detection 21 days – 230 events 60 seconds per activity Sampling frequency of 100 Hz.
![Page 26: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/26.jpg)
Results: real-time data analysis Communication complexity for various skew errors-rates over the
experiment-span
0
100
200
300
400
500
600
1 2 3 4 5 6 7 8 9 10
Skew Error in order of 10 ppm
Mes
sag
es E
xch
ang
ed in
10
00's
FTSP OTSP OTSP w ith caching
![Page 27: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/27.jpg)
Results: tossim simulation Average error per hop
Error per hop (for first hop): 4.52 milliseconds Error per subsequent hop : 1.24 milliseconds
Error in Time Synchronization
0
2
4
6
8
10
1 2 3 4
Hop distance from base station
Err
or
in m
illiseco
nd
s
Error in Time Synchronization
![Page 28: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/28.jpg)
Results: performance with frequency
![Page 29: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/29.jpg)
Results: performance with event density
![Page 30: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/30.jpg)
Results: miscellaneous observations Congestion Delivery probability
![Page 31: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/31.jpg)
Drawbacks
![Page 32: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/32.jpg)
Discussion
![Page 33: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/33.jpg)
Further Work
![Page 34: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/34.jpg)
![Page 35: On Demand Time Sychronizaton for Wireless Sensor Networks-november2009](https://reader036.fdocuments.in/reader036/viewer/2022062514/5591b4021a28ab3e2c8b45cc/html5/thumbnails/35.jpg)