Interference suppression in DS-PPM UWB systems

In this paper we consider a multiuser DS-PPM UWB transmission system with comb filter based energy detection and its improvement for the case of interchip and inter-interference. DS-PPM UWB provides good performance in WBAN environments under the assumption that the channel dispersion is shorter than one chip period. The performance could be highly degraded if this assumption is violated. To cope with the problem, a novel DS-PPM scheme - called DDS-PPM - is proposed in this paper. Optimal spreading sequence requirements are derived, which guarantee a suppression of the interference. It is shown that zero correlation zone sequences can be used to fulfill these requirements. Simulations with a WBAN channel show the excellent performance of the new scheme.