Research aimed at evaluating and improving wireless network protocols is hindered by the inability to perform repeatable and realistic experiments. While the physical layer can be ignored in wired networks, in wireless networks the physical layer fundamentally affects operation at all layers of the protocol stack. I will be assisting research aimed at building an emulator that accurately emulates wireless signal propagation in a physical space. The heart of the system is an FPGA that transforms the signals using realistic signal propagation models that will be developed as part of the project. The emulator can have a dramatic impact on the wireless networking community. Researchers establish shared benchmarks for evaluating wireless protocols. The project will develop both hardware and software needed for a useful emulator-based testbed. The result will allow researchers to quantify the relative strengths and weaknesses of competing wireless protocols in diverse physical environments. The emulator-based experiments will significantly improve our understanding of how signal propagation affects MAC layer protocol performance and it will allow us to evaluate and improve protocols.