PAWiS is an OMNeT++-based simulation framework for the optimization of wireless sensor networks (WSN). The simulator has been developed within the PAWiS project at the Institute of Computer Technology, University of Technology, Vienna. WSNs require nodes with exceptionally low power consumption, yet have to drive sensors and radio communication. Common optimization approaches concentrate on modules to make every module as good as possible, but this approach only reveals local optima. In contrast, the PAWiS Framework targets on cross layer and cross module optimization to find global optimum.