Non-coherent communication receivers (differential-detectors) have simple design, however, they always incur Bit Error Rate (BER) performance loss up to 3dB compared to coherent receivers. In this paper, a differential-detector is proposed for Impulse Radio Ultra WideBand (IR-UWB) communication systems. The system employs bit-level Differential Phase Shift Keying (DPSK) combined with Code Division (CD) for IR-UWB signals to support Multiple-Access (MA). It is analyzed under Additive White Gaussian Noise (AWGN) corrupted by Multiple-Access Interference (MAI) channel. Its BER performance is compared against a reference coherent receiver using Monte-Carlo simulation method.