Spectrally Compliant Waveforms for UWB Radio with an Auto-Correlation Criterion

A key feature of ultra wideband (UWB) communications is the high degree of multipath diversity in the channel. Although pulse shaping has been traditionally used to limit out of band emissions of the power spectrum, we show in this paper that the shape of the transmit monocycle can be leveraged to enhance the utilization of the available multipath diversity. In particular, we consider the IEEE 802.15.3a channel model with Rake receivers, where due to the large channel bandwidth, separation between the multipath components (MPCs) is extremely small. Thus, interference among the signal echoes is observed, with the result that the Rake outputs are correlated. It is shown that a monocycle with a narrow auto-correlation function (ACF) can mitigate the effect of self interference, and thus enhance the receiver performance. We also present new monocycles that carry a high energy content within the FCC spectral mask and possess narrow and rapidly decaying ACFs. While the high energy content enhances the signal to additive-noise ratio, the narrow ACF property maximizes energy-capture by the Rake receiver. Numerical results verify the performance gains accrued by employing these monocycles.