MoteFinder: A Deployment Tool for Sensor Networks

Rheinische Friedrich-Wilhelms-Universität Bonn
Institute for Computer Science IV
Sensor Networks and
Pervasive Computing Group
Römerstraße 164
D-53117 Bonn
MoteFinder: A Deployment Tool for Sensor Networks
Olga Saukh1, Robert Sauter1, Jonas Meyer2 and Pedro José Marrón1
1Universität
Bonn, Bonn, Germany and Fraunhofer IAIS, St. Augustin, Germany
2Structural
Engineering Research Laboratory, EMPA, Switzerland
{saukh, sauter, pjmarron}@cs.uni-bonn.de, jonas.meyer@empa.ch
Overview
 Motivation
 MoteFinder
◦ Hardware
◦ Software
 Performance Measurements
◦ Indoor Experiments
◦ Outdoor Experiments
◦ Advantages and Limitations
 Related Work
 Conclusions
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Motivation
 Many applications of wireless sensor networks
◦ Little deployment experience
◦ Many unexpected problems in the deployment phase
 “Smart-dust” as a nice vision …
◦ but we are still far away from the use of “throw-away” sensor nodes
▪ Sensor nodes are (still) rather expensive
▪ But already hard to find!
▪ Throwing away hardware and batteries is ecologically not acceptable
▪ Reuse of sensor nodes is possible
 Tools for the deployment phase are required
◦ MoteFinder: A Deployment Tool for Sensor Networks
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MoteFinder
 Is based on changing the omni-directional radiation/reception
pattern of a standard sensor node antenna to a narrow beam
◦ A Directed antenna that is cheap and easy to build!
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MoteFinder – Applications
 Selective interaction with one node or a group in the deployment phase
◦ Assignment of groups
◦ Node/Group configuration (position, …)
◦ Functionality check
◦ Measurement of the characteristics (e.g. TX-power) of individual sensor
nodes and performance assessment
 Automatic or semi-automatic localization and collecting sensor nodes after an
experiment
◦
◦
◦
◦
Can be combined with robotics
Environmental (and economic) considerations
Finding malfunctioning nodes
Tracking down of malicious sensor nodes that disturb the operation of the
network
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MoteFinder – Hardware
Cantenna
Tinfoil Cylinder
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MoteFinder – Hardware Properties
 Cost: a few Euros
 Cost: a few Cents
 Time to build: < half a day  Time to build: < half an
hour
◦ Measurements, drilling
 Reduces energy efficiency
 Mote modification
necessary
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MoteFinder – Software
LED blink frequency
Sensor nodes with a LCD
display
TinyOS Oscilloscope
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PDA display
Evaluation Criteria
 Proof of Concept
◦ Experiments with both Cantenna and Tinfoil Cylinder
◦ Various settings for the Transmission Power Level (TPL)
◦ Various distances
 Indoor and outdoor scenarios
 2D and 3D evaluated
◦ Different orientations of sensor nodes
◦ Different 3D placement of sensor nodes
◦ Different 3D orientation of the MoteFinder
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Performance Measurements – Settings
 32 markers of direction used
to measure angles
 Angle between two
neighboring markers is 11.2o
 5s time difference between
angle change
 160s one full circle
 All coordinates in cm
Z
XY-Rotation
Receiver
Beacons
MoteFinder
YZ-Rotation
(0,0,0)
Ground
ZX-Rotation
Y
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X
Close-by measurement
 Polar coordinates
 Recorded RSSI values
 Actual direction of beacons
(“mote”) shown




Cantenna
Distance: 40cm
TPL: 2
Two measurements:
◦ same node & same
settings
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Indoor Setup
 4 nodes located in different
rooms of an apartment
 Walls:
 made of brick,
 42cm thick (old building)
mote 23
(350,520,110)‫‏‬
mote 26
(-110,335,140)‫‏‬
 Beacons:
 TPL=5 (out of 31 for a
Tmote Sky)
MoteFinder
(0,0,50)‫‏‬
 Different orientation of
sensor nodes
 Different 3D locations of
nodes
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mote 25
(510,-310,70)‫‏‬
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mote 24
(108,-415,122)‫‏‬
0 degrees
Indoor Results
Cantenna
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Tinfoil Cylinder
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Outdoor Setup
mote 2
(0,300,0)‫‏‬
mote 3
(310,20,0)‫‏‬
MoteFinder
(0,0,31)‫‏‬
mote 1
(-150,-70,0)‫‏‬
 3 beacon nodes located outdoors
 Beacons:
 TPL=31
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Outdoor Results
Cantenna
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Tinfoil Cylinder
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Evaluation Results (1)
 Proof of Concept
 Both Cantenna and Tinfoil Cylinder can be used
◦ Cantenna performs smoother with changing angle
◦ Cantenna outperforms Tinfoil Cylinder with reasonable TPL settings both
indoors and outdoors
◦ Very rough error estimate: Cantenna ±30o, Tinfoil Cylinder ±45-60o
 Different values of Transmission Power Level
◦ Results show sensitivity to the TPL used by the beacon nodes
◦ Tinfoil Cylinder gives better results than Cantenna when used with
maximum TPL of beacons at short distances
▪ Due to higher gain of Cantenna, which could result in the saturation of the
input amplifier of the radio chip
 Different distances
◦ Due to higher gain of Cantenna, it can be successfully used at
considerably larger distances than Tinfoil Cylinder
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Evaluation Results (2)
 Indoor and outdoor scenarios
◦ Absence of obstacles reduces the error of direction estimates
◦ Tinfoil Cylinder performs smoother outdoors than indoors
 2D and 3D support
◦ Different orientation of sensor nodes
▪ Slight difference in RSSI depending on the orientation of sensor nodes
▪ Negligible compared to changes in RSSI when rotating MoteFinder
◦ Different 3D placement of sensor nodes and 3D orientation of MoteFinder
▪ Difference in 3D location of beacons and MoteFinder can slightly increase the
error of direction estimates
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Advantages and Limitations
 Advantages:
◦ Wide applicability:
▪ MoteFinder can be successfully used for indoor and outdoor scenarios
for both 2D and 3D settings
◦ The exactness of the results depends on
▪ Distance, presence of obstacles, TPL, MoteFinder itself
 Limitations:
◦ Only correctly formed messages are evaluated
◦ All beacons must include their IDs in the beacon messages to
distinguish nodes
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Related Work
 Cantennas
◦ Several works consider Cantennas for Wi-Fi networks
[Chebrolu et. al, 2006]
◦ Used for extending range, not for localization
[Johnson, 2007]
[Beyers, 2002]
◦ Rural areas and underdeveloped countries
 Directional Antennas in Sensor Networks
[Cho et. al, 2006]
◦ Longer lifetime by extending range of sink
[Nasipuri et. al, 2002]
[Rong et. al, 2006]
◦ Angle-of-arrival localization
 “Embrace and extend”
◦ Motes with LCD Displays, e.g., for deployment validation [Liu et. al, 2007]
[Kotay et. al, 2005]
◦ Equip robots with directional antennas for guidance
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Conclusions
 Cantenna and the Tinfoil cylinder work!
◦ Indoors and outdoors
 TPL/Antenna sensibility should be
adjusted to distance for optimum
performance
 Simple solution with lots of applications
◦ Deployment still difficult  Helpful
tools necessary
◦ Finding motes
◦ Selective interaction with groups/single
nodes
 Future work: Combine with sensors
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Thank you for Your Attention
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Are there any questions?
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Robert Sauter
sauter@cs.uni-bonn.de
Universität Bonn
Institut für Informatik IV
Sensor Networks and Pervasive Computing Group
Römerstr. 164
D-53117 Bonn
Germany
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