Overview of the ORBIT Radio Grid Testbed
for Evaluation of Next-Generation
Wireless Network Protocols
D.Raychaudhuri, M.ott, S.Ganu, K.ramachandran,
H.Kremo, R.Siracusa, H.Liu, Singh WINLAB
Reviewed by Lee YoungSoo
Motivation
 There is great deal of research activity on
future wireless/sensor networks and application.
Do not capture real physical layer effects.
 ORBIT aims to provide a flexible, open-access
multi-user experimental facility to support
research on next-generation wireless networks.
Difference from wired testbed
 Radio channel properties depend on specific wireless
node locations and surroundings.
 Physical layer bit-rates and error-rates are timevarying.
 Shared medium layer-2 protocols on the radio link
have a strong impact on network performance.
 There are complex interactions between different
layers
 User’s exhibit random mobility and location.
ORBIT testbed’s goal
 Scalability
 Reproducibility
 Open-access flexibility
 Extensive measurements capability
 Remote access
2-Tier ORBIT system architecture
ORBIT system architecture
Hardware components
 ORBIT radio nodes
1-GHz VIA C3 processor with 512 MB of RAM &
20GB local hard disk
Two wireless mini-PCI 802.11 a/b/g interfaces
Integrated chassis manager : remotely monitor the
status of each radio node’s hardware.
 Instrumentation subsystem
Provide capabilities for measurement of radio
signal levels & create artificial RF interference.
Hardware components
 Independent WLAN monitor system
Provide MAC/network layer view of radio grid’s
components
 Support severs
Front-end servers for web services and backend
server for experimentation and data storage.
Software components
 Management/
Control software.
 Software for
Radio nodes.
Management/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.
 Disk-Loading Server
Enable to quick re-imaging of hard disks on the
nodes as per the requirements of the user.
Measurement collection software
 ORBIT Measurement Library(OML)
Filters to be applied to each measured metric.
 Collection Server(CS)
Collect the reported measurements
Lifecycle of an Experiment
 The experiment details are translated into a script.
 The information is disseminated by Node Handler.
 The Node Agent executes the script.
Lifecycle of an Experiment
 Performs the experiment which may involves
statistics collection done by OML library.
 A separate run-time and post-experiment
database allows users to quickly view results.
Sample Experiment Results.
 Ex.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.
Sample Experiment Results.
Sample Experiment Results.
Sample Experiment Results.
 Ex.2) Effect of varying transmit power of
sender on the performance in the presence of
interferers.
Demonstrate the effect of changing the transmit
power of sender-receiver link.
One sender-receiver pair.
6 interferers.
Sample Experiment Results.
Sample Experiment Results.
 Ex.3) Multi-hop experiment with dual interface
forwarding node(FN)
Measure the improvement in network performance
for a multi-hop network with and without using a
dual interface forwarding node.
Sample Experiment Results.
Conclusion
 Present the design of a novel radio grid
emulator testbed that facilitate a broad range
of experimental research on next-generation
protocols & applications.
 Proof-of-concept validation of the testbed
design.