Overview of the ORBIT Radio Grid Testbed

for Evaluation of Next-Generation

Wireless Network ProtocolsD.Raychaudhuri, M.ott, S.Ganu, K.ramachandran,

H.Kremo, R.Siracusa, H.Liu, Singh WINLABReviewed by Lee YoungSoo

Motivation There is great deal of research activ-

ity on future wireless/sensor net-works and application. Do not capture real physical layer ef-

fects. ORBIT aims to provide a flexible,

open-access multi-user experimental facility to support research on next-generation wireless networks.

Difference from wired test-bed

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 ra-dio link have a strong impact on network performance.

There are complex interactions between dif-ferent 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 archi-tecture

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 moni-

tor the status of each radio node’s hardware. Instrumentation subsystem

Provide capabilities for measurement of ra-dio signal levels & create artificial RF inter-ference.

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 soft-ware.

Software for Radio nodes.

Management/Control software

Node Handler Disseminate experiment scripts using multi-

cast to the Node Agent. Node Agent

Reports back the state of experiment com-mand 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 re-search on next-generation protocols & applications.

Proof-of-concept validation of the testbed design.