This contribution deals with the application of multi-dimensional modulation (MDM) to UWB systems. As UWB is constrained in terms of energy consumption rather than bandwidth, binary modulation schemes are most attractive. By applying a multi-dimensional mapping scheme to UWB binary modulation, an iterative detector can be employed, operating according to the turbo principle. Mapping schemes with superior asymptotic performance are evaluated for time-hopping pulse position modulation and time-hopping bipolar modulation. Performance results are verified through computer simulations.