Multicode based communications in Impulse Radio UWB systems

In order to boost the data-rate in impulse radio UWB systems (which is necessary in some applications such as video stream), we propose to allocate more than one time-hopping code to the same user. In the case of a rake receiver, a new kind of interference associated with extra codes allocated to the user of interest is induced. Consequently the impact of these extra codes on the data rate is not straightforward. In order to evaluate the benefit of our proposition, we derive a closed-form for the multicode interference variance in the context of a time-hopping ultra wideband impulse radio based system. This enables us to theoretically analyze the influence of the number of additional codes on the real achievable data rate.