Ultra-Wideband (UWB) communications is an emerging new technology for high speed data transmission systems that is expected to enable low-cost and low-power devices. Instead of a modulated carrier, streams of ultra-short pulses (< 1ns) are used for wireless data transmission, yielding signals of huge bandwidths (> 1 GHz) but at very low power densities. In principle, the nature of the signal used makes the technology suitable for low-cost implementations in standard CMOS technology. However, before UWB systems can be produced at large scale and low cost, there are numerous open research issues to be solved. Only in recent years, the academic world has started research activities on a broad front, standardization and regulation authorities have become aware of the technology, and joint task-groups have been founded in the European Union and in the US. Previous experience with UWB technologies exists from military applications like UWB (time-domain, impulse) radar systems. Still research at fundamental and applied levels is needed at large scale to make cheap and power-efficient UWB chips available. In our research, we plan to go beyond the state-of-the-art in several areas related to the transceiver architecture and signal processing. Due to the extremely large bandwidth, which prevents direct sampling of the received signal at sufficient accuracy, it is expected that a straight-forward downscaling of signal processing algorithms for conventional receivers will not lead to practical solutions for UWB devices. That is, new algorithms for channel estimation, synchronization, multi-user detection, and other typical receiver tasks have to be developed for UWB devices. This includes the derivation of appropriate system models including the modeling of the multi-path radio channel as observed through antenna arrays. The following items will receive special attention: * Research on UWB channel models which include the multi-input/multi- output case * Research on UWB transceiver algorithms including adaptive antenna array algorithms and fading prediction * Optimization of transceiver algorithms for efficient hardware implementation