—In this paper we study a promising multiple access scheme entitled Channel Division Multiple Access (ChDMA). ChDMA was developed to cope with the particularities of low duty cycle Impulsive Radio Ultra Wideband systems (IR-UWB). The idea is based upon the fact that Channel Impulse Responses (CIR) could be exploited as users signatures. Based on the knowledge of the CIRs at the receiver, transmitted signals can be detected and estimated in a very similar approach as performed by DS-CDMA systems. We present in this contribution initial analysis of the spectral efficiency performance of ChDMA systems. As a matter of fact, ChDMA overcomes the multiple access paradigm of impulsive-radio signaling and provides an efficient and low complex technique to exploit the diversity of UWB communications. For the study, we consider three different receiver structures: optimal receiver, matched filter (MF) and linear minimum mean square error receiver (l-MMSE). As a result, it is shown that under certain conditions ChDMA can even outperform CDMA in terms of Shannon's capacity, providing a real option for future communication systems.