In this work we study the achievable rates of memoryless signaling strategies adapted to UltraWideBand (UWB) multipath fading channels. We focus on strategies which do not have explicit knowledge of the instantaneous channel realization, but may have knowledge of the channel statistics. We evaluate the average mutual information of general binary flash-signaling and achievable rates for m-PPM as a function of the channel statistics. Finally, we briefly examine the robustness of flash-signaling for interference-limited systems