Introduction

Good morning, Mr. Chairman and members of the Subcommittee.  I would like to thank you and the members of this Subcommittee for holding a hearing on this important topic.  The U.S. Department of Transportation (DOT) welcomes this opportunity to present its views on ultra-wideband (UWB) technology. 

DOT is first and foremost a public safety and security agency with responsibility for the Nation's transportation systems and those who use them.  In our continuing efforts to modernize and improve the safety, efficiency and security of our transportation systems, we have become increasingly reliant on access to spectrum to support a broad range of communications, navigation and surveillance (CNS) systems.  These systems are critical to the safe and efficient movement of people and goods in all modes of transportation and must remain absolutely reliable.  It is from this perspective that we approach new technologies, exploring their promise while adhering to the imperative that they not interfere with vital existing systems.  You will not be surprised to hear that, from DOT's vantage point, the assured integrity of these safety-of-life systems must be a given in the debate about new technologies.  The burden should be on the proponents of new technologies to demonstrate that their deployment will not diminish in any way that essential integrity. 

That is how we approach the ultra-wideband issue.  DOT fully supports the development and deployment of UWB technology.  Indeed, several UWB-based applications hold promise for improving transportation safety, such as ground-penetrating radar and potential collision avoidance systems.  But we seek assurances that UWB applications are deployed in a way that ensures the continued integrity of transportation-related safety-of-life systems. 

Spectrum Management Issues

The radio spectrum has become an indispensable resource.  The huge demand for access to spectrum has increased the potential for interference and this is a serious concern.  The Federal Government has a fundamental responsibility to ensure that the highest level of service is provided as we explore new and innovative ways to take advantage of radio spectrum. 

DOT makes every effort to scrutinize proposals to introduce new systems or technologies into the electromagnetic environment if they might affect transportation systems.  No matter what benefits are foreseen from a proposed new technology or application, we must be certain of its compatibility with existing systems in order to avoid potential conflicts with transportation-related services.  If, for example, the FAA's management of the spectrum is affected by unwelcome changes in the spectrum environment, the problem of flight delays might well be exacerbated.  FAA might have to slow down the National Airspace System to maintain safe operations. 

In the past, spectrum used for navigation was largely allocated exclusively for that purpose.  As pressure resulting from spectrum congestion increased, others sought to share the spectrum used for transportation safety systems - and they enjoyed some success in that regard.  That success, coupled with the recent rules adopted for UWB devices and the trend towards overlay of services different from the incumbent services, may seriously limit the ability of transportation industries to modernize their systems to keep pace with increasing demands. 

DOT's spectrum requirements are complicated by the fact that they are predicated on globally accepted protocols - notably in the case of aviation and maritime shipping.  For example, spectrum allocations and standards for aviation are developed by two United Nations organizations -  the International Telecommunication Union and the International Civil Aviation Organization.  Pilots who fly U.S.-registered aircraft between continents thus can be confident today that the avionics with which their aircraft are equipped will work as well overseas as they do in the U.S.  Maritime standards are developed through the International Maritime Organization and provide similar benefits for intercontinental maritime traffic.  The allocations and standards have taken many years and resources to adopt and implement.  It would take at least as many years to change them if rules that govern the use of UWB devices are not adequate. 

Critical CNS Systems

It is important to describe at least briefly the CNS systems for which DOT is responsible, and their location in the spectrum.  The importance of protecting them against the threat of interference - and the reasons for our concern about the deployment of UWB devices - are described below. 

First, roughly eighty percent of CNS systems used for air traffic control operate in bands below 960 Megahertz (MHz).  Additional systems operate in bands up to approximately 3 Gigahertz (GHz) to include the Global Positioning System (GPS), maritime radar, airborne collision avoidance, surveillance and communications systems.  Some additional critical systems lie between 4 and 6 GHz, including systems for weather radar, landing and airborne altitude measurement.  And still more scattered systems for various transportation modes use spectrum up to 90 GHz.  A more complete list of transportation systems is appended to my statement. 

DOT is particularly concerned about the effects of UWB emissions on the following systems: 

• Global Positioning System (GPS) (center frequencies at 1176, 1227 and 1575 MHz) - GPS is being implemented in the U.S. and globally to improve the safety and efficiency of land, air, and maritime transportation.  It is also used in many other applications, both civil and military.

• Various Aids to Navigation using frequencies below 960 MHz:

• Very High Frequency Omni-directional Range (VOR) equipment (108-118 MHz), one of the main en route navigation systems used globally by aircraft today.

• The Instrument Landing System (ILS) (108-111.95 MHz; 328.6-335.4MHz), an aviation precision approach and landing aid during severe weather and "no visibility" conditions.  It is the main system used both domestically and globally for these as an all-weather landing aid.

• Air Traffic Control Surveillance Radars

• Air Route Surveillance Radar-4 (ARSR-4) (1215-1390 MHz), the most modern of the long-range surveillance radars.

• Airport Surveillance Radar-9 (ASR-9) (2700-2900 MHz), an air traffic control radar used at numerous airports throughout the U.S. and its follow-on ASR-11.

• Systems around 5-6 GHz:

• The Microwave Landing System (MLS) (5030-5091 MHz), an aviation precision approach and landing aid for severe weather conditions - still used at some airports in the U.S. and currently being more widely implemented in Europe.

• The Terminal Doppler Weather Radar (TDWR) (5600 to 5650 MHz) that provides critical weather advisories for windshear and microburst phenomena to aircraft on final approach.

• The Runway Incursion System (5090-5150 MHz), a system in the early stages of development aimed at reducing the number of runway incursions, a top safety issue for aviation.

Protection of Vital CNS Systems is Paramount

These and other safety-of-life CNS systems are critical components of the national and international transportation infrastructure.  Ensuring the highest level of reliability for these systems and supporting technologies is essential to securing the safety of the traveling public.  For this reason, these critical systems operate in bands of the spectrum that are currently protected from the emissions of other systems.  That is why Part 15 unlicensed devices traditionally have been prohibited from producing intentional emissions - and their threat of interference - into these restricted bands. 

Historically, those who sought to use spectrum for a new purpose had to demonstrate that their operations would not interfere with existing systems.  We think that this is the appropriate approach.  A similarly cautious approach is indicated in the case of an emerging and unique technology like UWB, about which so much is still unknown. 

The Federal Communications Commission Decision

The Federal Communications Commission (FCC) Report and Order Regarding Ultra-wideband Transmission Systems (R&O), issued on April 22, was the product of a coordinated effort between the FCC, which regulates those portions of the radio spectrum dedicated to the private sector and to state and local governments, and the National Telecommunications and Information Administration (NTIA), which regulates the Federal government's portion of the spectrum.  When spectrum is shared between Federal and non-Federal users, as much of spectrum is, these agencies must coordinate the exercise of their authority as co-regulators.  DOT worked closely with both agencies as they prepared the R&O. 

The R&O approved operation of UWB equipment in three categories:  imaging systems, vehicular radar systems, and communications and measurement systems.  The first category includes ground penetrating radar, wall and through-wall imaging, and surveillance and medical imaging devices.  The second refers to devices mounted on vehicles to detect nearby objects.  The third includes home and business networking devices as well as storage tank measurement devices. 

Different technical standards apply to each - with specific frequency bands, emission limits, and operating restrictions.  For example, the use of imaging systems (other than in emergencies) will be limited to law enforcement, construction companies, and other entities, and subject to coordination with NTIA.  Communications and measurement systems will be allowed to operate only indoors or via hand-held devices.  In the R&O, the FCC also committed to undertake expedited enforcement action in the event of rule violations or harmful interference from UWB devices.  These protections - coordination and enforcement - are critical.  While the details of the coordination process remain to be developed, it is a crucial step toward avoiding and addressing potential interference with critical CNS systems.  As we move forward with implementing this rule, we look forward to working with NTIA and the FCC to define more fully the details of an effective coordination process.  

Rigorous enforcement of the FCC rule is also critical.  Such vigilance is necessary both because tests to date have demonstrated the potential for interference to CNS systems from UWB operations, and because experience with other wireless devices has shown that faulty manufacturing or design can lead to malfunctions and interference, even in equipment that is designed to protect against such interference.  For example, CNS systems have experienced interference in the past from malfunctioning Part 15 devices that are specifically designed to avoid intentional emissions into the restricted bands.  This interference has caused disruptions in the National Airspace System and has taken weeks or longer to find and mitigate.  We will work together with all appropriate parties to devise both a responsible and a responsive process that promptly and effectively identifies and resolves cases of interference. 

I might also note in this connection that DOT is not aware of any equipment currently available that can detect UWB devices, should they malfunction and need to be located.  The characteristics of UWB, such as wide bandwidth, make it very hard to detect.  While we are working to identify detection equipment, the lack of this equipment also argues for a cautious approach. 

The FCC, in the R&O, acknowledged that it was "proceeding cautiously . based in large measure on standards that the NTIA found to be necessary to protect against interference to vital federal government operations."  The FCC expressed concern as well, however, that these standards "may be overprotective and could unnecessarily constrain the development of UWB technology."   The Commission therefore announced its intent to review these standards within six to twelve months and "to explore more flexible technical standards and to address the operation of additional types of UWB operations and technology."

 Implementing the FCC Decision

As I indicated, DOT considers it prudent to approach new technology with caution where critical CNS systems are concerned.  There is no substitute for hard data, stringent analyses, and validation by tests.  As we move forward to implement the FCC rule, we are certainly prepared to explore with the FCC and NTIA whether, on the basis of additional information, the new standards may be either relaxed or strengthened.  The Department questions the adequacy of the timeframe announced by the FCC for this purpose, but we will strive to provide needed data and analyses. 

In this regard, DOT is instituting tests and analysis in areas where additional information is needed to determine possible effects on many of the systems mentioned earlier.  These efforts will focus on:

• The Global Positioning System - verifying previous test results.

• Air traffic control surveillance radars:

• The Air Route Surveillance Radar-4 - validating analysis.

• The Airport Surveillance Radar-9 - validating analysis.

• Systems below 960 Megahertz including:

• The Instrument Landing System - analysis and testing.

• Very High Frequency Omni-directional Range Equipment - analysis and possible testing.

• The Microwave Landing System - further analysis and possible testing. 

There are two points that I would like to emphasize.  First, while we appreciate that much attention has been given to protecting GPS, many of the technical solutions that would protect GPS from UWB interference are not necessarily transferable to other systems.  Because of different design characteristics, results derived from GPS analyses cannot simply be extended to other systems.  

Second, we must protect against even marginal degradations to our critical transportation systems.  Taking aviation as an example, even minor weather or other disruptions at an airport can result in delays and ground stops at other airports throughout the nation due to the ripple effect in our congested airspace.  Likewise, as policy makers, we need to be cautious of unknown impacts that may result from our decision on one issue, such as UWB technology, to be sure there are no adverse effects in other areas.  I have stated some examples of impacts that we believe warrant further scrutiny, such as aggregate noise effect due to proliferation of UWB devices and direct radio frequency interference to certain transportation safety systems that have not been fully analyzed and tested.  This is why the Department is so insistent that every effort is made to make the correct decision the first time. 

It should be noted that some ultra-wideband vendors have indicated a willingness to constrain the frequencies of their transmissions in order to be compatible with existing uses of the radio spectrum, while others have not.  The difference appears to be partly a matter of technology design and implementation, and partly of cost.  It is appropriate that any further consideration of rules governing UWB devices take this capability into account. 

But DOT's tests will supply only part of the data necessary to reach an informed decision on possible future UWB rules.  Additional analytical work is needed in two areas:  prototype testing and aggregation effects. 

Prototypes of proposed equipment are commonly tested to measure the characteristics of their emissions and their effects.  Unfortunately, prototypes of UWB devices have not been available for testing.  The FCC had hoped to gain experience on the impact of UWB devices on existing systems as a byproduct of the waivers it granted in 1999 to several UWB manufacturers.  To date none of these waivers has resulted in prototype devices for testing or useful test data.  Until this omission is corrected, crucial data will remain unknown. Before changes are made to the current rule, DOT, in conjunction with the NTIA, FCC and other Federal agencies, must be in a position to examine the results of prototype testing.  We look forward to working with NTIA, FCC and the industry in planning and conducting the appropriate tests. 

The aggregate effect of numerous UWB devices and their effect on the noise floor remains to be determined.  The noise floor is the level of background energy always present and is increased by emissions from manufactured devices.  Some systems like GPS operate below the noise floor level and may suffer reduced accuracy from additional energy in the noise floor.  As the use of UWB devices proliferate, we need to pay keen attention to their aggregate impact.  Opinions differ about any potential impact and we simply don't know enough about UWB at this time to draw firm conclusions in this regard.  We do, however, anticipate that UWB chips will increasingly be used in personal electronic devices.  The airline industry already has a growing concern over these personal electronic devices on aircraft.  Currently, such electronic devices are required to be turned off during certain critical phases of flight because of their potential for interference. 

Experience has shown that low-level signals from a number of otherwise benign devices can, in the aggregate, cause harmful interference.  A telling example of this impact has been the proliferation of microwave ovens in this country.  The frequency band in which they operate -- 2.4 GHz -- has been rendered useless for critical applications because the background noise level from microwave ovens has increased the noise floor by a thousand-fold, causing significant interference to other uses of the band. 

Conclusion

In summary, the Department of Transportation will continue to encourage the adoption of a cautious approach to the deployment of new technologies that have the potential to interfere with transportation-related safety-of-life systems.  We do not think the FCC has taken too conservative an approach.  As we work with NTIA and the FCC to implement and examine potential changes to this rule, we all must continue to demand the highest levels of protection for our transportation systems and for the safety of the traveling public.  I thank you for the opportunity to testify and I am happy to answer any questions you may have.