A novel scheme for ultra-wideband (UWB) monocycle pulse generation is proposed based on a dual-output push-pull Mach-Zehnder modulator (MZM). The MZM is driven by a non-return-to-zero (NRZ) data sequence and biased at the nonlinear point to generate edge-triggered pulses. To combine the complementary pulses forming a monocycle UWB pulse, two schemes are used to implement incoherent summation structure. A proof-of-concept experiment of UWB-over-fiber down-link system is set up. Further, by using digital signal processing (DSP) to calculate the bit error rate (BER), the transmission performance of two system configurations is studied.