The radio-frequency spectrum supports a vast array of government and commercial services, including radio and television broadcasts, personal communications services, satellite communications, wireless local area networks, public safety communications, air traffic control, scientific research, and radar-based weather forecasting. The radio spectrum spans a range of frequencies within the electromagnetic spectrum from about 3 kilohertz (kHz) to 300 gigahertz (GHz), but most of its use is concentrated in the lowest 1 percent of these frequencies—sometimes referred to as the “beachfront property” of the radio spectrum. Advances in technology have greatly expanded the usable portions of the radio-frequency spectrum and have led to more efficient means of using the available spectrum. Simultaneously, these advances have created opportunities to provide new spectrum-dependent services, which have led to even greater demand on the limited available spectrum. The spectrum is managed to maximize the benefits derived from this limited resource, while mitigating interference among various users. Within the United States, the spectrum is managed jointly by the NTIA, within the Department of Commerce, and the FCC. NTIA is principally responsible for developing and articulating domestic and international telecommunications policy and for managing the federal government’s use of the radio spectrum. FCC has authority over all nonfederal spectrum use, including the use of the spectrum by state and local governments. In managing the spectrum, FCC and NTIA have largely used a “command- and-control” approach, which dictates how each segment of the radio spectrum can be used and who can use it. This approach generally involves five steps: allocation, adoption of service rules or technical standards, certification, assignment, and enforcement. Table 1 describes each step. NTIA and FCC implement the command-and-control approach differently because of differences in their missions. For example, NTIA assigns spectrum resources through an administrative process that emphasizes interdepartmental advice and coordination among federal agencies, while FCC has used a number of administrative processes including comparative hearings and lotteries as well as its authority to assign spectrum through auctions. However, because so much of the spectrum is shared between federal and nonfederal users, FCC and NTIA must coordinate their management of spectrum. For many decades, command-and-control has been the most commonly used approach for managing the spectrum. However, as both the usage of and demand for spectrum have exploded over the past decade, the disadvantages of the command-and-control approach have become increasingly apparent. For example, in October 2001, the FCC Chairman noted that it is becoming difficult for government officials to determine the best use for spectrum and to repeatedly adjust allocations and assignments of spectrum to accommodate new spectrum needs and new services. The President has similarly noted that the existing legal and policy framework for spectrum management has not kept pace with the dramatic changes in technology and spectrum use and can discourage the introduction of new technologies. In June 2002, the FCC Chairman established a Spectrum Policy Task Force to help identify and evaluate changes in spectrum management policy and to provide specific recommendations to FCC for ways to evolve from the current command-and-control approach to a more integrated, market- oriented approach. In November 2002, the Task Force reported its findings and recommendations to FCC. While noting that no single regulatory model should be applied to all spectrum, the Task Force recommended that FCC pursue a spectrum management policy that includes both exclusive spectrum usage rights granted through market-based mechanisms and creates open access to spectrum “commons,” with command-and-control regulation used in limited circumstances. In January 2003, we issued a report recommending a commission be established to conduct a comprehensive examination of current U.S. spectrum policy. In May 2003, the President signed an executive memorandum establishing the federal government’s “Spectrum Policy Initiative” to develop recommendations for improving spectrum management policies and procedures for the federal government and to address state, local, and private spectrum use. Although work under the President’s initiative is ongoing, the initiative recognizes, along with the findings of the 2002 FCC Task Force, that existing and emerging technologies create the potential for future radios and other radio-frequency devices and systems to use spectrum more efficiently. Efficiency may be accomplished through improvements to a broad set of technologies and applications. Table 2 provides descriptions and key examples of such technologies and applications that can improve the utilization of spectrum. Many spectrum efficient technologies have both component-level and network-level attributes. For example, some “smart” antennas can pinpoint the source signal and selectively amplify it while canceling out competing signals. In addition, because smart antennas direct transmitted power toward desired receivers, the level of interference experienced by other spectrum users is reduced. This adaptive behavior may be controlled by local sensors but may also be cued by information provided through the radio’s network. Similarly, software-defined radios, unlike traditional radios, have operating parameters (such as the operational frequency and modulation type) that are determined by software, meaning they can be programmed to transmit and receive on many frequencies and to use any desired modulation or transmission format within the limits of their hardware designs; as with smart antennas, the programmed operating parameters of the radio may be controlled internally or may be cued through the radio’s network. FCC and NTIA are both charged with promoting the efficient and effective use of the radio spectrum. NTIA has told us that ensuring efficient use of the spectrum is a major NTIA goal reflected throughout most of its spectrum management processes, which include setting standards for equipment that use the radio spectrum, certifying that proposed new systems conform with existing spectrum allocations and associated standards, and requiring justification of frequency assignment requests and continuous review of existing frequency assignments. Additionally, NTIA is responsible for conducting spectrum analyses and research to keep abreast of the latest spectrum efficient technologies that are appropriate for government use and for developing and adopting automated information systems that support the spectrum management processes and facilitate appropriate spectrum conservation measures. Federal agencies have made some investments in technologies that may provide improved spectrum efficiency. However, their decisions to invest in those technologies are primarily driven by their individual missions— not by an underlying, systematic consideration of spectrum efficiency. Agencies generally do not identify spectrum efficiency as a distinct category of technology investment. Other considerations that influence agencies’ technology decisions include technical and operational concerns and costs that may make spectrum efficient technologies impracticable. Determining investments that may improve spectrum efficiency is difficult because agencies do not clearly identify spectrum-related investments in their budgets. However, using published budget and other information provided to us by each of the nine agencies, we identified projects that might result in improved spectrum efficiency and spoke with agency officials about their technology investments. Based on this review, we identified 335 fiscal year 2004 federally funded projects that potentially included funding for spectrum efficient technologies. Funding for these projects totaled approximately $1.8 billion. These investments cover a wide range of technologies that can affect spectrum use, including the compression of raw source data, advanced radios, and network improvements. The military services and Defense Advanced Research Projects Agency (DARPA) combined are by far the largest federal investors in new technologies that use the spectrum. In contrast, the Departments of Justice and Homeland Security have small research and development budgets and tend to rely on technologies that are commercially available. Table 3 provides the total fiscal-year-2004 funding identified for each agency’s projects related to spectrum efficiency and highlights major areas of investment. Agency investments in technologies that provide greater spectrum efficiency have tended to occur when agencies need to make greater use of available spectrum to meet a mission requirement and the additional spectrum is not readily available, as is the case with DOD. Specifically, DOD systems are requiring greater bandwidth to transmit intelligence and surveillance information, facilitate enhanced communications capabilities, and conduct electronic warfare—which DOD considers essential to meeting its key strategic goal of information superiority. As a result, DOD has made significant investments in new systems that, in part, address problems related to insufficient spectrum, as the following examples illustrate: Joint Tactical Radio System (JTRS): To address key communications shortfalls and significantly improve military capabilities, DOD has begun to make significant investments in software-defined radios, which offer the potential of more efficient spectrum use in the future without the need for expensive and complex hardware changes. In 1997, DOD initiated the JTRS program to develop and apply this technology and to bring together separate service-led programs into a joint software-defined radio development effort. JTRS radios are intended both to interoperate with existing radio systems and to provide military users with more flexible communications capabilities in the future. Air Force’s Transformational Satellite (TSAT) Program: The Air Force is exploring new technologies that enable communications in higher radio-frequency bands, which are much less congested, and in non-radio-frequency portions of the electromagnetic spectrum. Non- radio-frequency technologies will enable next-generation military satellites to communicate at very high data rates using lasers. As a result, information can be transferred without relying on the radio- frequency spectrum. DARPA’s Tactical Targeting Network Technology (TTNT) Program: TTNT program aims to demonstrate a high-capacity sensor data system that could enable networks of strike aircraft to accomplish their missions. In particular, certain missions require the rapid sharing of targeting sensor data among a large ad-hoc network of strike aircraft. Currently, the U.S. military’s airborne tactical data links cannot support a large network of aircraft simultaneously due to spectrum constraints. TTNT is expected to provide a data rate 10 to 25 times higher than the current airborne tactical data link in an equivalent amount of spectrum. Other agencies have made some investments in spectrum efficient technologies, and like DOD, these investments were largely driven by agency mission, as in the following examples: NASA’s Mars Laser Communications Demonstration Project: NASA anticipates a significant increase in the near future in demand for long-haul communications services from deep space to Earth.