Ultra wideband (UWB) offers the promise of new radar and imaging services that can save lives by helping to rescue hostages, locate disaster victims trapped under the rubble of a collapsed building, detect hidden flaws in the construction of highways or airport runways, secure homes and businesses, and possibly even provide short-range high-speed Internet access to the classroom.
UWB devices operate by employing very narrow or short-duration pulses that result in very large or wideband transmission bandwidths. Its ultrawide disbursement of ultra-low power bursts presents novel interference questions that must be addressed, including how to ensure that existing services are not adversely impacted—especially those services which support public safety—and whether widespread deployment would have any appreciable effect on the noise floor.
With appropriate technical standards, however, UWB devices can operate using spectrum occupied by existing radio services without causing interference, thereby permitting scarce spectrum resources to be used more efficiently. In early 2002, the Federal Communications Commission (FCC) issued standards designed to ensure that existing and planned radio services, particularly safety services, are adequately protected from UWB users.
The FCC will enforce the rules and act quickly on any reports of interference. The standards are based in large measure on standards that the National Telecommunications and Information administration (NTIA) believes are necessary to protect against interference to vital federal government operations. On an ongoing basis, the FCC intends to review the standards for UWB devices, explore more flexible standards, and address the operation of additional types of UWB operations and technology.
Since there is no production UWB equipment available at this writing and there is little operational experience with the impact of UWB on other radio services, the FCC chose to err on the side of conservatism in setting emission limits when there are unresolved interference issues. The FCC establishes different technical standards and operating restrictions for three types of UWB devices based on their potential to cause interference.
These three types of UWB devices are imaging systems, including groundpenetrating radars (GPRs), wall, through-wall, medical imaging, and surveillance devices; vehicular radar systems; and communications and measurement systems.
Imaging systems Provides for the operation of GPRs and other imaging devices subject to certain frequency and power limitations. The operators of imaging devices must be eligible for licensing, except that medical imaging devices may be operated by a licensed health care practitioner. At the request of NTIA, the FCC will notify or coordinate with NTIAprior to the operation of all imaging systems. Imaging systems include:
- Ground-penetrating radar systems GPRs must be operated below 960 MHz or in the frequency band 3.1 to 10.6 GHz. GPRs operate only when in contact with or within close proximity of the ground for the purpose of detecting or obtaining the images of buried objects. The energy from the GPR is intentionally directed down into the ground for this purpose. Operation is restricted to law enforcement, fire and rescue organizations, scientific research institutions, commercial mining companies, and construction companies.
- Wall-imaging systems Wall-imaging systems must be operated below 960 MHz or in the frequency band 3.1 to 10.6 GHz. Wall-imaging systems are designed to detect the location of objects contained within a “wall,” such as a concrete structure, the side of a bridge, or the wall of a mine. Operation is restricted to law enforcement, fire and rescue organizations, scientific research institutions, commercial mining companies, and construction companies.
- Through-wall imaging systems These systems must be operated below 960 MHz or in the frequency band 1.99 to 10.6 GHz. Through-wall imaging systems detect the location or movement of persons or objects that are on the other side of a structure such as a wall. Operation is limited to law enforcement and fire and rescue organizations.
- Medical systems These devices must be operated in the frequency band 3.1 to 10.6 GHz. Amedical imaging system may be used for a variety of health applications to “see” inside the body of a person or animal. Operation must be at the direction of or under the supervision of a licensed health care practitioner.
- Surveillance systems Although technically these devices are not imaging systems, for regulatory purposes they are treated in the same way as through-wall imaging and are permitted to operate in the frequency band 1.99 to 10.6 GHz. Surveillance systems operate as “security fences” by establishing a stationary radio frequency (RF) perimeter field and detecting the intrusion of persons or objects in that field. Operation is limited to law enforcement, fire and rescue organizations, public utilities, and industrial entities.
Surveillance systems Although technically these devices are not imaging systems, for regulatory purposes they are treated in the same way as through-wall imaging and are permitted to operate in the frequency band 1.99 to 10.6 GHz. Surveillance systems operate as “security fences” by establishing a stationary radio frequency (RF) perimeter field and detecting the intrusion of persons or objects in that field. Operation is limited to law enforcement, fire and rescue organizations, public utilities, and industrial entities.
Communications and measurement systems Provides for use of a wide variety of other UWB devices, such as highspeed home and business networking devices as well as storage tank measurement devices under Part 15 of the FCC’s rules subject to certain frequency and power limitations. The devices must operate in the frequency band 3.1 to 10.6 GHz. The equipment must be designed to ensure that operation can only occur indoors, or it must consist of handheld devices that may be employed for such activities as peer-to-peer operation.
UWB technologies are destined to play a significant public safety role. UWB devices will save the lives of firefighters and police officers, prevent automobile accidents, assist search-and-rescue crews in seeing through the rubble of disaster sites, enable broadband connections between home electronics, and allow new forms of communications in the years ahead. The U.S. government already uses UWB extensively to make soldiers, airport runways, and highway bridges safer.
But opinion differs greatly on the interference effect of the widespread use of UWB technologies by the public. If interference does occur, it conceivably could affect critical government and nongovernment spectrum users. National defense and several safety-of-life systems depend on bands that have the potential to be impacted by UWB devices. For this reason, the FCC and NTIAwill cooperate in managing the use of UWB technology.