Abstract: An UWB(ultra wide band) system usually transmits the same UWB impulse for all users. When many users are active in the system simultaneously, the effects of multi-userinterference are great and the system BER(bit error rate) is high. A TH-BPSK UWB system is proposed to decrease the effects of multi-user interference. Each user is assignedadifferent orthogonal UWB impulse of the modified Hermite polynomial function. Due to the orthogonality of UWB impulses, the multi-user interference can be eliminated completely if chip synchronism is assumed and the system BER performanceis enhanced. Simulation results and theoretical analysis indicate that the proposed system has much lower BER compared with the TH-BPSK UWB system using the same UWB impulse.

Key words: ultra wide band, Hermite function, orthogonality, TH-BPSK