This paper introduces M-PPAM(M-ary Pulse Position and Amplitude Modulation) architecture, combined PPM(Pulse Position Modulation) with PAM(Pulse Amplitude Modulation). Since M-PPAM can transmit several bits using one pulse, it is mon effective than PPM or PAM. Also, to obtain the same data transmission rate with PPM or PAM, M-PPAM can use a long pulse repetition period. This method will be able to use in the multi-path fading environment such as indoor condition. To accomodate multiple users, direct sequence technique is used. This paper has provided the modeling method of the M-PPAM DS-UWB receiver covering multi-user interference(MUI) with the Standard Gaussian Approximation under Gaussian channel. The performance of the receiver is simulated.