| Spectral Shaping of UWB Signals for Time-Hopping Impulse Radio |
| Citation: |
* Nakache, Y-P; Molisch, A.F., "Spectral Shaping of UWB Signals for Time-Hopping Impulse Radio", IEEE Journal on Selected Areas in Communications, ISSN: 0733-8716, Vol. 24, Issue 4, Part 1, pp. 738-744, April 2006 (PSD of UWB Signals) |
| Date: | April 2005 |
| MERL Contact: | Andreas F. Molisch |
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" TH-IR 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. |
|
