Electronic Design

Ultra Wideband: Get Ready For The Next Wireless Wave

Ultra-wideband (UWB) technology is getting hot. If you work in wireless and have yet to examine this unique methodology, you should get going because UWB is poised for application in next-generation wireless systems.

UWB, a developing form of radio, relies on very short RF pulses to transmit digital data. Also known as im-pulse, carrier-free, or baseband wireless, this spread-spectrum-like wireless technology uses an incredibly wide bandwidth. Its unique characteristics make it ideal for super high-speed data transmission and radar applications.

Discovered back in the 1960s, UWB was developed during the '70s and '80s. Initially, it was used in government and covert military applications. More recent developments have centered upon making it valuable in a variety of wireless products.

Some potential uses are in altimeters, short-range collision/obstacle-avoidance radar, and intrusion detection. UWB also can be used in secure tactical military radios. A major commercial application is high-speed (100 Mbits/s and higher) LANs/WANs. Plus, UWB is useful for seeing through obstacles like walls or the earth to detect nonmetallic objects. Other promising applications include precision geolocation and perhaps even future cell phones.

UWB transmits data in the form of very short RF bursts. A pulse may be as short as one cycle, or as many as several cycles. But it typically has a duration of hundreds of picoseconds and no more than a few nanoseconds. The pulse repetition rate is very high, producing a broad spectrum as dictated by the Fourier transform. Usually, the power level is only a few milliwatts. Data is encoded by pulse-time or pulse-position modulation, where a binary 1 may be a pulse that occurs earlier in time while a binary 0 is a pulse that occurs later in time.

The resulting spectrum can be many megahertz or even gigahertz wide. Typically, the 3-dB bandwidth is greater than 25% of the center burst frequency. Because of its spread-spectrum-like characteristics, UWB is inherently a multiple-access mode, permitting many users to share the spectrum simultaneously.

One big advantage is its ability to achieve data rates of 1 Gbit/s or more. So, it will make wireless LANs even faster. Also, because UWB is very much immune to multipath interference, it's useful indoors and where many obstacles exist. In addition, UWB's low-power, broadband nature makes it supremely secure. Its high frequency and speed make it especially useful in short-range radar that provides fine-range resolution and precision distance measurement.

The downside to UWB is that while the circuits are relatively simple, only recently have components become available to make practical systems. Moreover, the wide-bandwidth nature of UWB makes it more susceptible to noise.

Two major problems are holding UWB technology back—the patent mess and regulatory issues. The key patents and IP are held by only a few companies, so licensing is necessary, assuming that it's affordable. Also, the FCC and the NTIA haven't officially blessed UWB. Still, they're seriously considering its approval under the Part 15 rules and regulations in the very near future.

UWB looks like a winner for the next generation of wireless products. While things are quiet right now, more than a few new products based on this technology are expected soon. If you're in the wireless business and haven't investigated UWB yet, now is the time to act.

For details, check out www.uwb.org, www.wca.org, www.timedomain.com, www.fcc.gov, www.aetherwire.com, and www.multispectral.com.

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