Abbreviation for ultrawideband. 1. Referring to any radio or wireless device where the occupied bandwidth is greater than 25% of the center frequency or greater than 1. 5 GHz. 2. A radio or wireless system that uses narrow pulses (on the order of 1 to 10 nanoseconds,) also called carrierless or impulse systems, for communications and sensing (short-range radar. ) 3. A radio or wireless system that uses time-domain modulation methods (e.g., pulse-position modulation) for communications applications, or time-domain processing for sensing applications.