Ultra-Wideband: What is it?

There are many kinds of signaling that may be classified as "Ultra-Wideband", but what we are mainly interested in is an "Impulse Radio" (as opposed to one based on chirps or poly-cycles.)  This is essentially the mathematical dual of the conventional narrowband approach; where  sinusoidal signals are narrow in frequency and "wide" over time (see Figure 1 below),

a pulse is narrow in time and wideband in frequency (Figure 2 below).

One thing to note is that a pulse necessarily spreads its energy over a wide range of frequencies, albeit at a lower power level. This means that interference issues (those caused by the pulse as well as those caused by the presence of in-band sinusoids) will need to be seriously considered. The FCC has traditionally allocated radio use to specific frequency bands, and a special ruling was made recently to allow for ultra-wideband use. However, due to the issue of interference, ultra-wideband radios have to limit their transmit power to lower levels, thus limiting their use to short-distance applications (or lower data rates.) 

Why is Ultra-Wideband Attractive?

Two main properties of ultra-wideband make it an attractive choice for radio implementation: capacity and simplicity. The throughput of a channel is linearly proportional to the bandwidth, so an ultra-wideband system holds the promise of very high-rate communication.  Additionally, as ultra-wideband is essentially a base-band system, the analog front-end complexity is less than that for a traditional sinusoidal radio (see Figure 3 below).

This simplified transceiver seems to be easier to integrate (fewer components) and more naturally "digital" (pulse generation may be as simple as a digital switch) allowing it to take advantage of the flexibility, power scaling, and computational improvements associated with digital design. 

We are interested in investigating the nature of UWB communications; analyzing the repercussions of undetectable and non-interfering transmissions. We are also engaged in modeling and exploring system architecture options and looking into antenna/transceiver co-design issues (i.e. wideband matching.) In addition, we plan to identify low power CMOS circuit techniques that address the unique problems not encountered in narrowband designs and target the lowest possible cost and size. Ultimately it is our goal to demonstrate a working ultra-wideband radio prototype.

To learn more about UWB, explore some of the links below, and check out our LINKS page to other research, companies and organizations.

in addition, the following links below are recommended: