What is Ultra Wideband?
Ultra wideband (UWB) signals are electromagnetic waves with instantaneous bandwidth greater than 25% of the center operating frequency or an absolute bandwidth of 1.5 GHz or more. UWB, also known as impulse or zero carrier radio technology, is a wireless communication technology fundamentally different from all other radio frequency (RF) communications. UWB is unique in that it achieves wireless communications without using an RF carrier. Instead it uses modulated pulses of energy of less than 1 picosecond in duration. The more common approach of pulse position modulation (PPM), for instance, might assign a digital representation of 0 or 1 to the transmitted and received pulse, based on where in time the pulse is placed. Each pulse, when applied through a Fourier transform formula, can be shown to exist simultaneously across an extensive band of frequencies. However, the distributed energy of the pulse at any given frequency exists in the less-than-noise-level range. This allows UWB signals to coexist with RF carriers with no discernable interference, thereby opening up vast new communications territories and possibilities by providing tremendous wireless bandwidth to ease the growing bandwidth crunch.
Why is UWB Becoming a Viable Solution?
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UWB is only becoming commercially viable because of:
* Federal Communications Communication (FCC) recognition
* Decreased costs and advancements in chip development
* The evolution of the marketplace
The Birth of UWB
UWB research started in the early 1940s. The U.S. military re-invented it under a cloak of secrecy and black projects from the 1960s to the 1990s, where UWB was particularly well-suited to modern radio detection and ranging (radar) and highly secure communications.
FCC Recognition of UWB
In 1998, the FCC recognized the significance of UWB technology and began the process of regulatory review. In May 2000, the FCC issued a Notice of Proposed Rulemaking, accepting comments for review. Throughout 2001, comments and review from the FCC, National Telecommunication and Information Administration (NTIA), Department of Commerce (DOC), and Department of Defense (DoD) were received. The formal rule change was posted on February 14, 2002, and the birth of a new era began. The revision to the standard represents a cautious first step with UWB technology. It is based on standards that the NTIA believes are necessary to protect against interference with vital federal government operations. At this time, only prototype UWB products are available, which is why the FCC chooses to be conservative in setting the emission limits and is waiting to review production units to see if the standards can be relaxed.
UWB presents a compelling solution to many of the challenges facing today’s wireless industry. By many accounts, an impeding crunch in RF spectrum availability will impede the evolution of wireless technologies. UWB does not use an RF carrier, which opens up vast new spectrum. Variations in RF spectrum assignments from one country to the next prohibit global interoperability for RF-based devices. Without such RF limitations, UWB offers the promise of global interoperability. RF spectrum is so extensively allocated that there is no RF bandwidth available to match UWB bandwidth potential. Devices using RF spectrum are more complex, cost more, consume more power, and don’t have the data rates that UWB has. UWB operates at lower-than-noise level and offers greater security than RF. UWB, as a byproduct, offers inexpensive geographic positioning.
From an architectural standpoint, UWB can cost less than carrier-based technologies. Carrier-based technologies must modulate and demodulate a complex analog carrier waveform and incorporate the components required to do so. UWB, on the other hand, offers a truly binary form of communication that can essentially be boiled down to four components. The first is the UWB transmit/receive section. The second is a UWB antenna. Third is a digital baseband processor that handles such tasks as picketing data and forward error correction. Fourth is the embedded firmware and protocols that drive the digital baseband processor.
Will UWB Cost Less than Current Wireless Technology?
There are several areas for reduced cost because of the nature of UWB. UWB technology is possible on a silicon germanium (SiGe) micro-chipset that will cost less than $30 by its first production cycle. The digital nature of the UWB transmission requires fewer components than are needed in today’s frequency-based wireless devices. That is because they must modulate and demodulate a complex analog carrier RF waveform (the frequency carrier). UWB’s microwatt power consumption is another factor allowing greater cost reduction.
The Advantage of Using UWB
The advantage of UWB is that it can penetrate at signal power. For instance, an unfiltered pulse of 200 picoseconds duration, when applied through a Fourier formula, demonstrates signal energy throughout the spectrum between direct current (DC) and 10 GHz. Obviously this is not a perfect square wave representation because the pulse is subject to some coloring from the antenna – and antenna technology is an extremely important facet of UWB technology – but with proper antenna implementations, the distribution of energy is spread fairly evenly across the spectrum. A UWB receiver detects the presence of the energy of the pulse in time, not at specific frequencies. So absorption of specific carriers such as at 1.8 GHz or 2.4 GHz has little effect so long as about 50% of the spectral energy density of the pulse penetrates whatever obstacles lie in the transmission path. Absorption at any one particular frequency does little to affect the integrity of the actual pulse.
Potential Commercial Applications
Potential commercial applications include distribution of wireless audio, video, and data over local area networks (LAN) for home, office, and boats. In addition UWB has the unique ability to resolve global position location to centimeter accuracy as a byproduct of sending and receiving data between multiple UWB devices. And last, UWB has applications to wireless Internet- and video-capable devices with extremely accurate GPS-like positioning, such as personal digital assistants (PDA), laptop computers, and automobiles, and digital video cameras and a wide range of consumer electronics and home appliances.
Currently there are no standards for UWB. But standards activities have commenced and are critical for full deployment in commercial markets. Standards are necessary to validate the technology and provide avenues for interoperability and coexistence, while identifying core requirements such as scalability and interference robustness, specifically in the physical layer (PHY) and the medium access control (MAC) layer. The PHY or OSI Layer 1 is composed of the baseband function and the radio. The MAC or (OSI Layer 2) includes the processor and the software protocol stack. The IEEE 803.15.3 will be submitting a request for proposals for standards by the middle of 2003. The approved standard will not be available until 2005, and could prolonging the advances of UWB technology even more.
Allied Business Intelligence Inc is an Oyster Bay, NY-based technology research think tank that offers expert advice and research on wireless, broadband, and emerging technologies. Details can be found at www.alliedworld.com or by calling 516-624-3113.