Early Results on Hydra: A Flexible MAC/PHY Multihop Testbed

Hydra is a flexible wireless network testbed being developed at UT Austin. Our focus is networks that support multiple wireless hops and where the network, especially the MAC, takes advantage of sophisticated PHY techniques, such as OFDM and MIMO. We argue that for this domain simulation alone is not adequate and that working prototypes are needed to validate algorithms and protocols. Hydra nodes consist of a flexible RF front-end and a general purpose machine with a software based MAC and PHY. Using the frameworks of the Click modular router and GNU radio and coding in C++ makes it relatively easy to implement working prototypes of cross-layer designs that require custom MACs and PHYs. We present the architecture and implementation of Hydra, as well as a preliminary cross-layer design experiment for a rate-adaptive MAC. These early results show Hydra is a capable prototyping tool for wireless network research.