The Nexus framework anticipates the influence of the general computational development towards the so-called state of Ubiquitous Computing, where not only most electronic devices but even those objects which today have no electric supply will be aware of their position and context and be able to communicate among each other. This will be a kind of a by-product of the ongoing miniaturization of electronic components, growing performance of processors and memory and at the same time dropping prices. By using this communication capability and the collected spatial information, the Nexus framework will provide a platform for multiple spatial aware services for mobile people and self organizing applications. For making mobile objects spatial aware, numerous sensors are needed, which can be placed on the object itself as well as in the stationary environment. In addition, simulation of physical mobility helps to bridge the lack of spatial sensor data or in a first phase generates virtual sensor data for test purposes for Nexus components and applications. The simulation and modeling research in our subproject focuses on two aspects of user mobility: the mobility of pedestrians and the mobility of motor-driven vehicles. As for our proposal to the SIIV Congress, we want to place emphasis on aspects of microscopic simulation of pedestrian mobility. As it is one of the most important objectives of the Nexus project, our main concern in the field of pedestrian simulation is the scalability of our modeling methods to large areas, e.g. to large (pedestrian) networks. Therefore we mainly focus on two dimensional cellular automata. By this way, we can reduce long range effects in a complex simulation environment to a relatively small calculation rule set. We are integrating several, partly already well known approaches to pedestrian simulation based on cellular automata into a comprehensive simulation platform. This allows us to reproduce phenomena like lane formation, crossing behavior, oscillations at doors and even panic situations. We are testing our simulation platform on a rather complex geometric environment (the campus of the University of Stuttgart), which comprises indoor, as well as outdoor situations. Because of the need of more precise geometric data, we are also developing an interface for the exchange between CAD and GIS formats and the spatial world model format of Nexus. Up to now, there are unfortunately no satisfying ways of evaluating the quality of microscopic pedestrian simulations. The most frequently used method is a heuristic comparison between the visualization of the simulation and the reality. For that reason, a comprehensive microscopic census of pedestrian mobility within the campus area, comprising video analysis and detailed counts will be carried out in the first half of 2005. As for the SIIV Congress, we will present first results of the evaluation through real pedestrian mobility data of our microscopic pedestrian simulations based on cellular automata.