Abstract
We propose and demonstrate experimentally, for the first time, a prototype for
all-optical ultra-wideband (UWB) transceiver at 500 Mb/s. We report 1) UWB pulse
optimization that takes into account the transmitter RF front end and the U.S. Federal
Communications Commission (FCC) spectral mask, 2) a new approximate match filter
receiver using optical signal processing, and 3) modulation at 500 Mb/s. Our previous
optimization of UWB pulse shapes was based only on the FCC spectral mask, without taking
into account the frequency response of the RF components (amplifier and antenna) in the
UWB transmitter. Here, we modify our pulse optimization technique to ensure that the
equivalent isotropic radiated power (EIRP) from the transmitter meets FCC
specifications. For the RF hardware used, we achieve 63.6% efficiency over the FCC mask,
which yields an 11.6- and a 5.9-dB improvement over Gaussian monocycle and doublet
pulses, respectively. We also introduce simple optical signal processing at the receiver
that allows the incoming RF signal to be matched against a square pulse whose duration
is adapted to the channel. The exact matched filter would require a new optimized pulse
that would include not only hardware frequency response but channel effects that vary
with antenna placement as well. The proposed approximation allows a simple variation of
the pulse duration: an increase to account for pulse expansion in the channel but an
upper limit to combat multipath effects. Finally, we demonstrate the optimized pulse and
approximate match filter receiver at 500M/s. We attain a 10<sup>-6</sup> error
rate at a 65-cm separation line of sight (LOS) link with simple on-off keying and no
forward error correction.
© 2008 IEEE
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