  In this paper, we investigate a new waveform for UWB systems obtained by the
combination of Orthogonal Frequency Division Multiplex (OFDM) and Code Division
Multiple Access (CDMA). The proposed system, called Spread Spectrum -
Multi-Carrier - Multiple Access (SS-MC-MA) turns out to be a judicious solution
to combat frequency selectivity and narrowband interferers, and to manage the
coexistence of several users and piconets. It is shown that the addition of a
degree of freedom brought by the spreading component of SS-MC-MA allows to
optimize jointly the assignment of the number of used codes and coding rates in
order to make the system more robust. Through simulations, it is demonstrated
that the new system can outperform Multi-Band OFDM Alliance (MBOA) for low data
rates and is able to provide wider range of rates.
