BUILDING CYBERINFRASTRUCTURE IN DEEP WOODS AND REMOTE WATERSHEDS Gayatri Venkatesh, Kuang-Ching Wang...
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Transcript of BUILDING CYBERINFRASTRUCTURE IN DEEP WOODS AND REMOTE WATERSHEDS Gayatri Venkatesh, Kuang-Ching Wang...
BUILDING CYBERINFRASTRUCTURE IN DEEP WOODS AND REMOTE
WATERSHEDS
Gayatri Venkatesh, Kuang-Ching Wang
Department of Electrical and Computer Engineering
The Intelligent RiverTM Pilot Sites
Over Woods & Hills
To campus
In Woods & Ditches
To campus
In the Woods
AT&T Data Coverage
Along the River
Challenges and Objectives
• Wireless networking challenges– Deep woods – impedes wireless communication range– Lack of cellular coverage– Hilly terrains – absolute blockage, often over long
distances– Recurring cost and limited bandwidth of cellular/satellite
service
• Wireless networking objectives– A methodology for building wireless network
infrastructure for current and future Intelligent RiverTM sites that
• provides adequate and reliable bandwidth• scales to a large area physically and economically
Clemson Forest and Hunnicut Creek
• Explore higher bandwidth, lower cost technologies– Clemson Forest
• Long range Wi-Fi (fixed direction): IEEE 802.11a & b/g
• Wi-Fi mesh network: IEEE 802.11b/g
• Zigbee sensor network: IEEE 802.15.4
– Hunnicut Creek
• Long range Wi-Fi (steerable direction): IEEE 802.11b/g
• Wi-Fi mesh network: IEEE 802.11b/g
• Zigbee sensor network: IEEE 802.15.4
Forest and Hunnicut Network Overview
Long Distance Transit Links
• To overcome long distance, forests, hills– Radio placement on high structure on both ends– High gain directional antenna and power
amplifiers– Potential control parameters
• Radio transmit power• Antenna direction• Antenna gain• Radio layer 2 and 3 protocol parameters
Clemson Forest Sensor Network
• Zigbee
• Zigbee• Zigbee• Zigbee• Zigbee
• Zigbee• Zigbee• Zigbee
• Long range Transit Link
• SensorCluster
• Data
Short range Wireless Communication: ISM 2.4 GHz
operating frequency .
1 mW (+0 dBm) power output.
Up to 120m range.
Supports up to 16 simultaneous channels.
Steerable Directional Antenna Radio
• Potentially higher bandwidth at substantially longer distance
• Software controls radio to focus one direction at a time– Fidelity Comtech Phocus System (tested 15 miles line-of-sight
range)– Potential use as 1) forest mesh routers and 2) long range
gateways
Measurement Studies of the Links
Long Range LinksIPERF – Bandwidth measurement tool used for the performance studies
Laptop connected to the a radio on the fire tower ran as Iperf server and the laptop connected to radio on clemson campus ran as Iperf Client.Observation: The long range line-of-sight link stayed connected for about 30° with a throughput insensitive to transmit power changes.
Iperf server
Iperf client
-90-85-80-75-70-65-60-55-50-45-40
-20 -10 0 10 20 30Horizontal Antenna Angle (Degrees)
Sign
al S
tren
gth
(dBm
)
0
4
8
12
16
20
Thro
ughp
ut (M
bps)
Signal Strength Throughput
-80
-75
-70
-65
-60
-55
-50
12 14 16 18 20 22 24Transmit Power (dBm)
Recei
ved S
ignal
Stren
th (dB
m)
Long range link:Throughput v.s. signal strength v.s.antenna direction
Long range link:Signal strength v.s.transmit power
Measurement setup
Measurement Studies of the Links
Forest Mesh LinksTwo Linksys routers with manufacturer default omni-directional antennas were placed in a wooded area with roughly uniformly grown trees.
It was found that the received signal strength decreased consistently with distance.Throughput remained steady for over 120 ft and had an unexpected rise afterwards before losing connectivity.Increasing transmit power did not increase the received signal strength and throughput in this environment.
20 40 60 80 100 120 140 160 180 2000
5
10
15
Thro
ughp
ut (M
bps)
20 40 60 80 100 120 140 160 180 200-100
-80
-60
-40
Router Distance (ft.)
Sign
al S
tren
gth
(dBm
)
26mW 50mW 70mW
Forest mesh link:Throughput v.s. signal strength v.s.distance in forest
Measurement Studies of the Links
Steerable Antenna LinksTwo Fidelity routers with phased array directional antennas
were placed 525 ft a part on an empty parking lot. The antenna beam width was configured to be 35 vertical and 43
horizontal. Starting from line of sight (0), one antenna rotated away in 22.5
steps until reaching 180 (facing away from the other antenna).
0 45 90 135 1800
10
20
Th
rou
ghp
ut
(Mb
ps)
0 45 90 135 1800
20
40
60
Antenna Orientation (Degrees from Line-of-Sight)
SN
R (
dB
)
10 dBm 4 dBm 2 dBm 1 dBm
Throughput v.s. signal strength v.s. antenna direction
The short range directional antenna link’s angular range of connection depended sensitively on transmit power.
Throughput was stable when connected but dropped steeply at the edge
Future Work
• Clemson Forest and Hunnicut networks ready for integration– Sensor packets pushed to server successfully (server
integration TBD)– Video camera to be installed in Clemson forest– Mesh routers ready for larger scale deployment
• Reliability and controllability are key concerns for a large scale sensing system– Further measurement studies to develop forest model for
studying wireless network performance and design– Further studies on assessment and control techniques for
wireless network performance and reliability– Further studies on developing large scale wireless network
management techniques and software
Acknowledgements
• Dan Schmiedt , CCIT Chief Network Engineer• Knight Cox, Clemson Forest Manager• CCIT Intelligent River Project Team• Clemson Public Services Activities Team• Cisco Systems Inc.