Spectral shaping of UWB signals for time-hopping impulse radio

This paper studies the design of signaling waveforms for time-hopping impulse radio (TH-IR) with limits on the power spectral density. Such restrictions are imposed by the spectral mask prescribed by frequency regulators for ultrawideband (UWB) signals. The "conventional" THIR system with pulse-position modulation and time-hopping multiple access gives rise to spectral lines that either violate the regulations, or require a significant power back-off. To remedy this situation, we propose the use of polarity randomization, which eliminates the spectral lines and also leads to a smoothing of the continuous part of the spectrum. We analyze different variants of the polarity randomization, considering short and long randomization sequences, as well as symbol-based or pulse-based randomization. We analyze the effect of this technique on both PPM and BPSK modulation. IEEE Journal on Selected Areas in Communications This work may not be copied or reproduced in whole or in part for ...

• Type: Journal
• Year: 2006
• Where: JSAC
• Authors: Yves-Paul Nakache, Andreas F. Molisch
• Keywords: Electric Research Laboratories, JSAC 2006, Mitsubishi Electric Research, Polarity Randomization