Performance of UWB time-hopping spread-spectrum impulse radio in multipath environments

This paper presents the theoretical analysis of BER performance for ultra wideband (UWB) impulse radio systems in multipath propagation channels. Both time-hopping pulse-position-modulation (TH-PPM) and the time-hopping pulse-amplitude-modulation (TH-PAM) are considered. The closed-form BER formulas are derived. The impact of system parameters on the BER performance is discussed. It is demonstrated that the impact of multipath propagation on TH-PAM UWB radio is different from that on TH-PPM UWB radio, which is analyzed in detail. For the TH-PPM scheme, the multipath propagation time-delay may lead to unbalanced BER over "0"-"1" in some particular multipath channels. For the TH-PAM scheme, however, there exists no such unbalance of BER over "0"-"1". In typical deterministic multipath environment, to obtain the same BER performance of 10/sup -4/, the required SNR for TH-PPM scheme is about 7dB larger than that for TH-PAM.