Wireless networking research lacks a comprehensive experimental environment that supports implementation, validation, deployment, performance evaluation and comparison of research ideas. While some open wireless testbeds [1, 2] have taken important steps to create such an environment, they typically provide researchers only access to a set of mesh nodes, an operating system distribution and scripts to run experiments. Hence, implementation of an idea still remains significantly difficult-for instance, even modification of MAC or transport protocols require invasive kernel changes. What researchers need is an easy-to-use environment that provides them (1) a protocol toolkit: to implement and modify only the necessary elements and not an entire system and (2) reconfiguration ability: to easily configure nodes as well as network protocols both in an offline and online manner. To the best of our knowledge, no open wireless testbed exists that satisfy both (1) and (2). Another deficiency of current wireless research networks is that they do not typically serve user traffic. This prohibits evaluating solutions in a realistic manner. Having real users in a testbed creates a unique opportunity for testing protocols with real traffic and mobility patterns. However, it also creates the need to reconcile two different worlds: the worlds of users and researchers. Real users expect a reliable network access and demand privacy. On the contrary, a research network is an unstable environment with frequent outages. To support both real users and ease-of-use, all the components of the experimental environment need to be designed with these two factors in mind. Additionally, it is necessary to provide automated and online reconfiguration of the network. Furthermore, reconfigurations should be coupled with fail-safe mechanisms to ensure the reliability of the user traffic. These capabilities enable the network to run without downtime.

We are designing such an environment in Berlin. The Berlin Open Wireless Lab (BOWL) 1 is an open wireless mesh testbed designed to provide Internet access to real users (ie the TU-Berlin community) and an experimentation environment to researchers in wireless mesh networking. BOWL has two essential capabilities: