Low-Complexity Optical Distribution of Gb/s BPSK UWB Signals

Optical transport of ultra-wideband (UWB) signals extends the reach of these power-limited signals to several kilometers. We propose and experimentally demonstrate a simple and low-cost optical method to generate UWB pulses. We use few optical components (source/modulator/photodetector), in contrast to most other optical generation techniques. UWB pulses complying with the U.S. Federal Communications Commission spectral mask are generated by modulating the intensity of a continuous-wave laser with a combined signal consisting of the data signal and a sinusoidal signal. For impulse radio UWB, binary phase-shift-keying is accomplished simply by adjusting the amplitudes of the data and the sinusoidal signal. Wireless propagation of the UWB impulses is investigated experimentally at a very high bit rate. The receiver is implemented using a real-time oscilloscope to capture the received waveforms followed by offline signal processing. In particular, we consider a minimum-mean-square error equalizer to counter the multipath-induced intersymbol interference encountered at 1.75 Gb/s. Equalization brings the bit-error-rate within the forward-error correction limit of after 2.5 m of wireless propagation at 1.75 Gb/s.