Performance Evaluation of Direct Sequence Ultra Wideband Systems in Multipath Fading Channels

Ultra Wideband (UWB) technology has attracted considerable interest in the research and standardization communities, due to its promising ability to provide high data rate at low cost with relatively low power consumption. UWB is characterized by transmitting extremely short duration radio impulses. The signal energy is thus spread over a band of frequencies up to a few GHz. In this paper we outline the attractive features of direct sequence ultra wideband systems employing antipodal signaling (DS_BPSK). First, we compare TH_PPM and DS_UWB in terms of their multiple access performance in AWGN environment. Compared with TH_UWB, results show that DS_UWB supports a larger number of users communicating at higher data rates. Then, we evaluate the multiple access performance of DS_UWB in multipath fading channels. We consider partial Rake receiver structure with different number of Rake fingers. Results show that DS-UWB system using Rake receiver is able to sustain BER less than 10e-5 even in channels suffering from severe multipath fading. Using 10 fingers Rake receiver, about 12 dB improvement in performance of system can be achieved.