Distributed Implementation of a Wireless Network Emulator

by
Vaibhave Agarwal

Advised by
Jay Lepreau

Test and performance evaluation of protocols and algorithms in wireless networks is challenging. Simulation, although flexible, does not support real applications and developers must provide models for the communication stack, new testing protocol and even the applications being used. Testbeds using real wireless links are expensive, less flexible than software implementation of channel models, and do not provide repeatability. Network emulation provides a controllable and reproducible environment that supports real applications. Moreover, the emulator can be flexibly configured such that predefined network conditions and traffic dynamics can be generated in an automatic manner.

We present an 802.11 wireless emulator that utilizes commodity PCs on a high speed wired LAN to do a distributed emulation of the wireless network, as opposed to the central emulation done by available wireless emulators. A key aspect of our approach is to broadcast all packets on the wired LAN, with each receiver keeping a separate but consistent wireless media model, by emulating the CSMA/CA media access algorithm used in real wireless networks. We aim to get higher throughput and scalability than centralized wireless emulators, while retaining accuracy sufficient to accurately model many practical scenarios.