MOTEL: Towards Flexible Mobile Wireless Sensor Network Testbeds Alexander Förster, Anna Förster, Tiziano Leidi, Kamini Garg, Daniele Puccinelli, Frederick Ducatelle, Silvia Giordano and Luca M. Gambardella Abstract Performance evaluation of wireless sensor network (WSN) applications is a complex process consisting of several interleaved steps. Starting from theory, researchers first test their ideas in simulation, then on an indoor testbed, proceed to a small deployment prototype and finally the deployment itself. While the overall approach is well-designed and guarantees testing in various environments, its current implementation practice is not ideal. Main problems are missing code portability and high implementation costs of experimental testbeds. Additionally, current indoor testbeds do not provide the developers the full spectrum of real world challenges and requirements, such as real battery behavior, outdoor scenarios, or mobility of nodes. This paper presents FLEXOR, a flexible, lightweight and user-friendly software architecture and environment for designing and developing wireless sensor network applications. It is platform independent, highly modularized and supports mobile testbed features, such as on-node data logging, remote node management, and remote module activation and de-activation. The developer can either choose from a rich pool of available modules or implement new ones. Modules are then connected into a system specification, consisting for example of several communication protocols, an application and WSN specific algorithms. Several system specifications can be available simultaneously on any sensor node and can be switched on/off as required. We have already implemented FLEXOR for TinyOS and an implementation for the event based simulator OMNeT++ is in work.