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.
Ultra wideband usually refers to a radio communications technique based on transmitting very-short-duration pulses, often of duration of only nanoseconds or less, whereby the occupied bandwidth goes to very large values. This allows it to deliver data rates in excess of 100 Mbit/s, while using a small amount of power and operating in the same bands as existing communications without producing significant interference. However it is not limited to wireless communication, UWB can also use mains-wiring, coaxial cable or twisted-pair cables to communicate - with potential to deliver data faster than 1 gigabit per second.
UWB ultra wideband uwb is fundamentally different from all other radio frequency communications. It is unique in that it achieves wireless communications without using an RF carrier. Instead it uses modulated high frequency low energy pulses of less than one nanosecond in duration. Since the actual transmission is physically a wavelet, some authorities consider it to be true wavelet-modulated radio.
There are two major methods used to modulate waveforms: Time-modulated pulse-position modulation and bi-phase-modulated pulse-amplitude modulation[1]. By long-established practice, UWB is considered to occupy a fractional bandwidth of 20% or greater, or a bandwidth of 250 MHz or more, of spectrum. The U.S. Federal Communications Commission (FCC) restricts UWB to fractional bandwidth of 20% or greater, or bandwidths of 500 MHz or more (not 250 MHz). In December 2004 ultra wideband the FCC effectively eliminated this minimum bandwidth requirement as to the 5925-7250 MHz and 16.2-17.7 GHz frequency bands.
The processing gain of UWB, defined as the ratio of occupied bandwidth relative to the modulation bandwidth, is similar to spread spectrum for transmission. However, UWB is only typically able to benefit from processing gain during transmission. Reception of UWB is usually based on time-correlation of pulses, and the receiving benefits of processing gain possible with ultra wideband amp with shutdown spread spectrum are not usually realized in practice. Additionally, UWB has difficult-to-realise synchronization requirements (for semiconductor ultra wideband technology companies) due to the very low Duty cycle pulses employed. One way to effectively overcome both of these issues is by using a massively parallel DSP front end operating at more than 2.4 teraops/second. There is at least one company successfully using this approach for its first-generation silicon.
On February 14, 2002 [FCC15 2002] the FCC approved a spectral mask for operation of UWB devices. The major part of it lies between 3.1 and 10.6 GHz (from the middle of S band through to the middle of X band) with allowed effective isotropically radiated power (EIRP) of -41.3 dBm/MHz. It has been proposed that impulse radio systems (that transmit very narrow pulses) are good candidates to satisfy these constraints. OFDM-based technologies also meet ultra wideband wireless FCC requirements. In March 2005 the FCC granted a waiver that benefits both so-called multiband OFDM (MB-OFDM), which "hops" an OFDM signal from one band to another, and gated direct sequence ultra-wideband (DS-UWB), which occupies a much wider swatch of spectrum but switches on and off while in operation. The waiver allows both technologies to take their measurements for compliance with the -41.3 dBm/MHz limit in their normal operating mode -- i.e., with the hopping or gating turned on. The practical effect is to boost the useful operating power by several dB.
There are a number of competing standards which makes universally compatible UWB products problematic in the short-term. Recently, however, both Wireless USB and 1394 have standardized on the WiMedia (MB-ODFM) radio. In addition, Bluetooth stakeholders have expressed an interest in using UWB at the core of their next-generation standards. UWB signaling is being considered a potential candidate for the alternate physical layer protocols for the high data rate IEEE 802.15.3a standard as well as the low data rate IEEE 802.15.4a "ZigBee" wireless personal area network (WPAN) standards. The IEEE 802.15.4a standard aims at providing a physical layer wireless communication protocol with ranging capabilities for low-power applications such as sensor networks. The narrow duration of the UWB pulses enable in achieving stringent (<1m) ranging requirements.
See also
- IEEE 802.15.3a
- Bluetooth
- Wireless
- Network
- Bandwidth
- Fat-Pipe
- Wideband
- Wavelet
- IEEE 802.15.4a "ZigBee"
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
- UWB Radio Technology Primer on UWB
- The UWB Forum The UWB Forum is dedicated to ensuring that standards-based Ultra-Wideband products from multiple vendors are truly interoperable – from mobile phones to set-top boxes, from computers to televisions to digital camcorders and more.
- 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.
Chip manufacturers
- Pulse-Link Pulse-Link is a fabless semiconductor providing UWB solutions at Gbit/s rates on-air and over wired media
- Time Domain Time Domain is a fabless semiconductor company, and is a UWB pioneer providing time-modulated pulse based UWB solutions
- Freescale Semiconductor Manufacturer of DS-UWB chips sets and evaluation kits demonstrating FCC certified 114 Mb/s radios
- Alereon Alereon, Inc. is a fabless semiconductor company providing complete solutions for Certified Wireless USB and WiMedia ultra-wideband (UWB) applications.
- TZero TZero
- Staccato Staccato Communications
- Artimi Artimi
- WiQuest WiQuest
- Wisair Wisair
Electronics Topics
The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.
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