An OFDM-CDMA Scheme for High Data Rate UWB Applications

In this paper, we investigate a new waveform for UWB systems obtained by the combination of orthogonal frequency division multiplex (OFDM) and coded 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.