Ultra wideband

Ultra-wideband (also UWB, and ultra-wide-band, ultra-wide band, etc.) may be used to refer to anything with a very large bandwidth (e.g.: a type of sampling rate in the Speex speech codec). This article discusses the meaning in radio communications.

Overview

Ultra-Wideband (UWB) is a technology for transmitting information spread over a large bandwidth that should, in theory and under the right circumstances, be able to share spectrum with other users. A February 14, 2002 Report and Order by the Federal Communications Commission (FCC) authorizes the unlicensed use of UWB in 3.1–10.6 GHz. This is intended to provide an efficient use of scarce radio bandwidth while enabling both high data rate personal-area network (PAN) wireless connectivity as well as longer-range, low data rate applications as well as radar and imaging systems. More than four dozen devices have been certificated under the FCC UWB rules, the vast majority of which are radar, imaging or positioning systems. Deliberations in the International Telecommunication Union Radiocommunication Sector (ITU-R) have resulted in a Report and Recommendation on UWB in November of 2005. National jurisdictions around the globe are expected to act on national regulations for UWB very soon.

Ultra Wideband was traditionally accepted as impulse radio, but the FCC and ITU-R now define UWB in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% bandwidth. Thus, pulse-based systems—wherein each transmitted pulse instantaneously occupies a UWB bandwidth, or an aggregation of at least 500 MHz worth of narrow band carriers, for example in orthogonal frequency-division multiplexing (OFDM) fashion—can gain access to the UWB spectrum under the rules. Pulse repetition rates may be either low or very high. Pulse-based radars and imaging systems tend to use low repetion rates, typically in the range of 1 to 10 megapulses per second. On the other hand, communications systems favor high repetition rates, typically in the range of 1 to 2 gigapulses per second, thus enabling short-range gigabit-per-second communications systems. Each pulse in a pulse-based UWB system occupies the entire UWB bandwidth, thus reaping the benefits of relative immunity to multipath fading (but not to intersymbol interference), unlike carrier-based systems that are subject to both deep fades and intersymbol interference.

The FCC power spectral density emission limit is the same as for unintentional emitters in the UWB band, but is signficantly lower in certain segments of the spectrum.

Possible applications

Due to the extremely low emission levels, UWB systems tend to be short-range. However, due to the short duration of the UWB pulses, extremely high data rates are possible, and data rate can be readily traded for range by simply scaling the number of pulses per data bit. Conventional OFDM technology can also be used subject to the minimum bandwidth requirement of the regulations. High data rate UWB can enable wireless monitors, the efficient transfer of data from digital camcorders, wireless printing of digital pictures from a camera without the need for an intervening personal computer, and the transfer of files among cell phone handsets and other handheld devices like personal digital audio and video players.

UWB also has the potential to enable "see-through-the-wall" imaging technology and high-precision time-of-arrival-based localization approaches. Performance of Ultra-Wideband Time-of-Arrival Estimation Enhanced With Synchronization Scheme

References

External links

The Ultra-Wideband Radio Laboratory at the University of Southern California has many publications including "Low Noise Amplifier Design for Ultra-Wideband Radio" by Jongrit Lerdworatawee, Won Namgoong, 2003
uwbforum The uwbforum is an open, non-profit industry association dedicated to collaboratively developing and administering specs from the physical layer up; enabling connectivity and interoperability for multiple industry-based protocols.
UWB Radio Technology Primer on UWB
WiMedia Alliance The WiMedia Alliance is an open, non-profit industry association dedicated to collaboratively developing and administering specs from the physical layer up; enabling connectivity and interoperability for multiple industry-based protocols sharing the MBOA-UWB spectrum.
UWB Info and resources
FCC Docket file on UWB

Chip manufacturers

Semiconductor companies providing complete solutions for Certified Wireless USB and Bluetooth 3.0, based upon the WiMedia ultra-wideband (UWB) technology

Software providers

Microsoft Microsoft Windows Drivers (including WHCI—wireless host controller interface)
Stonestreet One Windows and Embedded drivers for UWB Hardware

Radio modulation modes

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