Overview of the ORBIT Radio Grid Testbed
for Evaluation of Next-Generation Wireless Network Protocols
WCNC 2005D.Raychaudhuri, M.ott, S.Ganu, K.ramachandran,
H.Kremo, R.Siracusa, H.Liu, SinghWINLAB, Rutgers University
2011.4.11Presented by Mingu [email protected]
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Contents• Radio channel characteristic• Limitation• ORBIT testbed
– Requirement– Overall architecture– HW / SW component
• Experiment• Conclusion
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Radio channel characteristic• Radio channel properties depend on spe-
cific wireless node locations and surround-ings
• Physical layer bit-rates and error-rates are time-varying
• Shared medium layer-2 protocols on the radio link have a strong impact on network performance
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Limitation• Primarily simulation based or small in-
house experimental setups• Difficult to repeat same experiments• Excessive setup and data collection times
Hinder rapid prototyping and experimentation
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ORBIT TESTBED
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Background• Seeded by NSF grant under the Network-
ing Research Testbeds (NRT) program• Collaborative effort: Rutgers, Columbia,
and Princeton, along with industrial part-ners Lucent Bell Labs, IBM Research and Thomson
• Developed and operated by WINLAB, Rut-gers University
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Requirement• scalability, in terms of the total number of
wireless nodes (~100’s)• reproducibility of experiments which can
be repeated with similar environments to get similar results
• extensive measurements capability at ra-dio PHY, MAC and network levels, with the ability to correlate data across layers in both time and space
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Requirement (cont’d)• remote access testbed capable of un-
manned operation and the ability to ro-bustly deal with software and hardware failures
• open-access flexibility giving the experi-menter a high level of control over proto-cols and software used on the radio nodes
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ORBIT: Indoor Grid
Not yet
Implemented part
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Hardware component• ORBIT radio nodes
– 1-GHz processor with 512 MB of RAM
– 2 wireless mini-PCI 802.11 a/b/g interfaces
– Chassis manager : re-motely monitor the status of each radio node’s hard-ware
• Instrumentation sub-system– Provide capabilities for
measurement of radio sig-nal levels & create artificial RF interference
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Hardware component (cont’d)• Independent WLAN
monitor system– Provide MAC/network
layer view of radio grid’s components
• Support severs– Front-end servers for
web services– Back-end servers for
experimentation and data storage
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Software component• Software packages and libraries developed
to support both application/protocol evalu-ations – Common libraries for traffic generation, mea-
surement and collection– Easy hooks to enable "expert"
• To develop their own applications, protocol stacks, MAC layer modifications and/or other experiments
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Control software• Node Handler
– Disseminate experiment scripts using multicast to the Node Agent• Node Agent
– Reports back the state of experiment command execution to the Node Handler
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• Disk-Loading Server– Enable to
quick re-imaging of hard disks on the nodes as per the re-quirements of the user
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Measurement software• ORBIT Measurement Library (OML)
– Filters to be applied to each measured metric• Collection Server (CS)
– Collect the reported measurements
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EXPERIMENT
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Experiment flow• The experiment details are translated into a script• The information is disseminated by Node Handler• The Node Agent executes the script
OML Server
USER / CONTROLLER
OBSERVER SERVICES
GRID
Node configuration- Select nodes- Configure interfaces
Application configuration- Download application and libraries- Configure application parameters
OML configuration- Configure measurement collection
parameters
Experiment Script
DB
Nod
eHan
dler
Nod
eAge
nt (p
er n
ode)
OML Client (per node)
START
END ww
w Fetch results
Experiment details
Run time statistic
collection
Off-line Storage of results
Display
Sta
ticD
ynam
ic
(Change channel, power, sleep on/ off etc during experiment)
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Experiment 1• To study the effect of 802.11b interference
on the performance of a link under test– Consist of 8 nodes, send UDP packets– 6 interfering nodes, send UDP packets
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Experiment 2• Effect of varying transmit power of sender
on the performance in the presence of in-terferers– Demonstrate the effect of changing the trans-
mit power of sender-receiver link– One sender-receiver pair– 6 interferers
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Conclusion• Present the design of a novel radio grid
emulator testbed that facilitate a broad range of experimental research on next-generation protocols & applications
• Provide sample experiments as proof-of-concept validation of the testbed design
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Q & A
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