Capacity of Impulsive Modulation over Multipath Interference Channels

We extend results regarding the most favorable degree of impulsive interference to the case of a sparse multipath channel. The system under investigation is of multiple un-synchronized communication links, each employing randomly spread ternary (0,+1,-1) CDMA signaling. It is assumed that the channel-state information, i.e., the instantaneous interference level from neighboring links, is available at the decoder, and this interference is considered as noise. We show that for a fixed average transmission power, the Shannon capacity of the system is maximized by the most impulsive signaling, i.e., spreading patterns consisting of a single non-zero chip. This strengthens our earlier results for the two-user single-path channel case.