Overview of the ORBIT Radio Grid Testbed for Evaluation of Next-Generation Wireless Network Protocols

1. D.Raychaudhuri, M.ott, S.Ganu, K.ramachandran, H.Kremo, R.Siracusa, H.Liu, Singh WINLAB Reviewed by Lee YoungSoo Overview of the ORBIT Radio Grid Testbed for Evaluation of Next-Generation Wireless Network Protocols

2. 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.

3. Difference from wired testbed • Radio channel properties depend on specific wireless node locations and surroundings. • 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. • There are complex interactions between different layers • User’s exhibit random mobility and location.

4. ORBIT testbed’s goal • Scalability • Reproducibility • Open-access flexibility • Extensive measurements capability • Remote access

5. 2-Tier ORBIT system architecture

6. ORBIT system architecture

7. 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.

8. 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.

9. Software components • Management/ Control software. • Software for Radio nodes.

10. 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.

11. Measurement collection software • ORBIT Measurement Library(OML) • Filters to be applied to each measured metric. • Collection Server(CS) • Collect the reported measurements

12. 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.

13. 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.

14. 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.

15. Sample Experiment Results.

16. Sample Experiment Results.

17. 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.

18. Sample Experiment Results.

19. 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.

20. Sample Experiment Results.

21. 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.