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What is UWB?
UWB is short for Ultra Wide Band, a wireless communications technology that transmits data in short pulses which are spread out over a wide swath of spectrum. Because the technology does not use a single frequency, UWB enjoys several potential advantages over single-frequency transmissions. For one, it can transmit data in large bursts because data is moving on several channels at once. Another advantage is that it can share frequencies that is used by other applications because it transmits only for extremely short periods, which do not last long enough to cause interference with other signals.

What are the uses for UWB?
It is believed that many uses will be discovered but much depends on what the U.S. Federal Communications Commission (FCC) will allow. If the FCC relaxes its rules in the future, a wide range of wireless data communications devices could become available, such as wireless networks with far greater bandwidth than existing technologies like Bluetooth, 802.11a and 802.11b. The FCC's current rules (issued on February 14, 2002) allow only the following:

• Automotive collision-detection systems and suspension systems that respond to road conditions.
• Medical imaging, similar to X-ray and CAT scans.
• Through-wall imaging for detecting people or objects in law-enforcement or rescue applications.
• Construction applications, including through-wall imaging systems and ground-penetrating radar.
• Communications devices, such as high-speed home or office networking, provided that the devices are designed for indoor use; outdoor use is restricted to handheld devices engaged only in peer-to-peer operation.

What is the potential for UWB as a networking standard?
Because UWB has the ability to penetrate walls and transmit data at rates up to 1 gigabit per second, it is could have the ability to become the center of all communications within a single location, such as a home or small office environment. That means the same devices could contain the data to support high-speed Internet traffic, streaming video, and phone.

Why is the FCC involved?
The FCC regulates all use of radio-emitting devices within the United States. It has the authority to prohibit operation of any device that emits an electro-magnetic signal if it interferes with the operation of any device that the FCC has approved.

How does UWB work?
UWB is based on a technology known as spread spectrum. In its original concept, spread spectrum conveyed data using a series of short radio pulses that were transmitted at different frequencies within a specific range of spectrum. The technique was first used by the U.S. military to ensure that it's communications could avoid detection by enemies in World War II. Because the signals at any specific frequency were incomplete, the enemy was not able to intercept the entire message. Spread-spectrum was widely used by the military for years in secure communications. In 1985, the FCC, opened up three bands for spread-spectrum use in local communications devices, establishing a 1 watt power limit as a way of preventing interference; the technology was used in a variety of communications devices. For example, cordless telephones and wireless local-area-network products using spread-spectrum are now common. UWB adds several layers of sophistication to the spread-spectrum concept: it varies a radio pulses's amplitude, polarity, timing and other characteristics to form a data stream that can be carefully controlled using packets and error-correction methods. A UWB data transmission may involve billions of pulses spread over several gigahertz.

Why is the FCC restricting UWB?
Concern about interference with existing radio transmissions. The FCC establishes rules on the types of applications allowed at each frequency in the radio spectrum and no space is left unclaimed. Control over frequency is very carefully controlled; public corporations pay large sums to operate exclusively within those frequencies. (A January, 2001 auction held by the FCC elicited bids of about $13 billion for licenses to operate advanced communications services within the United States.) As one might expect, when the FCC announced that it was considering relaxing the rules for UWB to operate within spectrum that had already been licensed, a number of companies raised objections (the FCC is required by law to allow the public a chance to comment on its proposed regulations). In issuing it's rules for UWB on February 14, 2002, the FCC commissioners said that they were taking extreme care to avoid any possible interference and believes that after a trial period, the commission will be able to broaden the UWB applications permitted. The spectrum that the FCC has proposed for UWB devices now being used by the GPS (Global Positioning System) and GPR (Ground Penetrating Radar). UWB proponents believe that UWB pulses will not cause interference with these other applications. because the pulses continuously change frequencies. and operate at low power levels.

If there are so many complaints, why has the FCC approved UWB to be used?
It is the FCC's legal mandate to ensure that the country is able to develop a free and competitive marketplace for communications, so it must avoid placing unnecessary restrictions on technology. The FCC says that it believes the concerns over interference are not warranted. In announcing the current guidelines it has also limited usage to such low power that it believes will minimize any potential problems.

What about concerns that the GPS system will be disrupted?
When UWB was first proposed, the U.S. Department of Defense was quick to raise concerns about the integrity of the GPS (Global Positioning System). The FCC spent two years evaluating tests of its proposed UWB authorization and concluded there will be no interference. The Department of Defense issued statements suggesting that it is satisfied with the results of those tests and the current restrictions being placed on UWB.

Who is developing UWB devices?
Time Domain, a startup with patented designs for UWB communications, is one of the most early leaders in the field and their applications cover a wide range of UWB applications. Xtreme, Intel, Lucent and AT&T are among the companies who have expressed interest in developing UWB devices capable of carrying voice, data and possibly video.

What kind of data communications applications can we expect to see?
The current rules limit communications devices to low-power use that prevents them from working beyond a relatively short distance (about 30 feet). However, it is believed that if the current rules prove UWB will not cause interference with existing RF devices, higher power devices could be approved.

What is the next step?
The FCC has said it will review within six to 12 months the rules it issued on February 14, 2002. During this review period, it will be reviewing comments made by the advocates of UWB and critics.

What are the problems facing UWB?
Because UWB uses a wide swatch of frequency, there are concerns that it will interfere with existing communications.