Transmitter-Side Multipath Preprocessing for Pulsed UWB Systems Considering Pulse Overlapping and Narrow-Band Interference

We analyze a prerake diversity combining scheme for pulsed ultrawideband systems to shift signal processing needs from the receiver to the transmitter. We consider the realistic case that received pulses carrying the same transmitted symbol could overlap with one another in optimizing the prerake scheme based on zero-forcing and eigenanalysis techniques. We show that in the presence of interpulse interference caused by pulse overlapping, the optimum prerake combining scheme in the sense of maximizing the received signal-to-noise ratio derived by using the eigenanalysis technique performs the same as a conventional rake with maximal ratio combining. We also analyze the different behaviors of prerake and rake schemes in the presence of tone interferers and provide numerical results to validate the conclusions in the presence of in-band-modulated interferers. We find that when the number of narrow-band interference (NBI) signals is small, the prerake scheme outperforms the rake scheme; as the number of NBI sources increases, however, this performance gap reduces.