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 Chomgcho@mmlab.snu.ac.kr

MMLAB

Contents• Radio channel characteristic• Limitation• ORBIT testbed

– Requirement– Overall architecture– HW / SW component

• Experiment• Conclusion

2/20

MMLAB

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

3/20

MMLAB

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

4/20

MMLAB 5

ORBIT TESTBED

MMLAB

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

6/20

MMLAB

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

7/20

MMLAB

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

8/20

MMLAB

ORBIT: Indoor Grid

Not yet

Implemented part

9/20

MMLAB

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

10/20

MMLAB

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

11/20

MMLAB

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

12/20

MMLAB

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

13/20

• Disk-Loading Server– Enable to

quick re-imaging of hard disks on the nodes as per the re-quirements of the user

MMLAB

Measurement software• ORBIT Measurement Library (OML)

– Filters to be applied to each measured metric• Collection Server (CS)

– Collect the reported measurements

14/20

MMLAB 15

EXPERIMENT

MMLAB

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)

16/20

MMLAB

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

17/20

MMLAB

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

18/20

MMLAB

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

19/20

MMLAB

Q & A

20/20