Master's Thesis
2006
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, the protocol being tested and even the applications being used. Testbeds using real wireless links are expensive, less flexible than software implementation of channel models, and sometimes do not provide repeatability. Network emulation provides a controllable and reproducible environment that supports real applications. Moreover, an 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 a wireless network, as opposed to the central emulation done by other 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. In addition to static wireless nodes, our emulator also supports mobility, with each node only having to keep track of its own movement pattern. We obtain higher throughput and scalability than centralized wireless emulators, and show that it is as accurate as the PHY and MAC layer models we have used.