The performances of a PCTH-based communication UWB system with diversiform modulation schemes are compared on the classic AWGN channel propagation and the realistic IEEE-UWB channel model. By employing different versions of modulation at the transmitters, the performances of an optimal receiver and a Rake receiver with various combining schemes are studied in this paper. The numerical results for several compared cases illustrate the tradeoff between transmitter diversity and receiver complexity. It is shown that the actual performance of the PAM-PCTH scheme can be better in both kinds of channel propagation. We also find that the PCTH-based UWB system with the Rake receiver has better performance than the conventional proposal for overcoming the multipath propagation effects in the UWB indoor environment.