The National Telecommunications and Information Administration (NTIA) is the Executive Branch agency principally responsible for developing and articulating domestic and international telecommunications policy. Accordingly, NTIA conducts studies and makes recommendations regarding telecommunications policies and presents Executive Branch views on telecommunications matters to the Congress, the Federal Communications Commission (FCC), and the public. NTIA also serves as manager of the Federal Government's use of the radio frequency spectrum.
The President signed an executive memorandum dated October 13, 2000, that stated the need and urgency for the United States to select radio frequency spectrum to satisfy the future needs of the citizens and businesses for mobile voice, high-speed data, and Internet-accessible wireless capability; the guiding principles to be used for the development of third generation (3G) wireless systems; and the direction to the Federal agencies to carry out the selection of spectrum. The President directed the Secretary of Commerce to work cooperatively with the FCC to develop a plan to select spectrum for 3G wireless systems, and to report on the current spectrum uses and the potential for reallocation or sharing of the bands identified at the International Telecommunication Union (ITU) 2000 World Radiocommunication Conference (WRC-2000) that could be used for 3G systems.
The objectives of this study were to document the Federal Government use of the 1710-1850 MHz band, and to address other issues relevant to the possible accommodation of 3G mobile systems in this band. These issues include sharing options, continuity of Federal operations, time lines for relocation, and the estimated costs related to any relocation of Federal users from the band.
Spectrum Under Consideration
The 1710-1885 MHz and 2500-2690 MHz bands were two bands, among others, identified by the WRC-2000 as additional bands for 3G mobile systems, also called International Mobile Telecommunications-2000 (IMT-2000). The United States is planning for the introduction of IMT-2000 services by commercial providers, but unused spectrum to accommodate such services is currently not available. Both NTIA and the FCC are examining these candidate frequency bands (1755-1850 MHz and 2500-2690 MHz, respectively) identified by the conference that are under their respective jurisdictions, with a view towards accommodating IMT-2000 systems. Since the WRC-2000 identified these candidate bands for IMT-2000 operations, promoting worldwide harmonization of spectrum is a desired long-term goal.
The 1710-1755 MHz band will be transferred to the FCC on a mixed-use basis pursuant to the requirements of the Omnibus Budget Reconciliation Act of 1993 (OBRA-93), and the National Defense Authorization Act (NDAA) for Fiscal Year 1999, but Federal operations can continue in the band within 16 protected areas. The Federal Power Agencies and public safety fixed links will also be protected. The 1850-1885 MHz band is under FCC regulatory jurisdiction and is currently used for personal communications services (PCS). The remaining 1755-1850 MHz band, which is the focus of this study, is under the jurisdiction of NTIA. Within the United States, the 1755-1850 MHz band is allocated on an exclusive basis to the Federal Government for fixed and mobile services. Footnote G42 to the National Table of Frequency Allocations provides for the co-equal accommodation of Federal space command, control, and range and range-rate systems for earth station transmission in the 1761-1842 MHz band. The Department of Defense (DOD) is the predominant user of the 1755-1850 MHz band. However, 13 other Federal agencies operate extensive fixed and mobile systems in this band throughout the United States.
In addition to the above two bands identified by the conference, other bands that could be considered in the United States are: 698-746 MHz, 747-762 MHz, 777-792 MHz, 806-960 MHz, 1850-1990 MHz, 2110-2150 MHz, and 2160-2165 MHz.
The FCC, in conjunction with NTIA, is expected to identify spectrum by July 2001, and auction licenses to competing applicants by September 30, 2002. The following report provides NTIA’s assessment of the potential for accommodating 3G mobile systems in the 1710-1850 MHz band, including the feasibility of sharing the band, operational impacts to incumbent users, and estimated relocation costs in the event that incumbent users would be required to relocate to alternate spectrum. The FCC report on the 2500-2690 MHz band, addressing similar issues, will be released concurrently by the FCC.
This report examines the technical feasibility of accommodating 3G systems in the 1710-1850 MHz band, and develops the estimated costs associated with any relocation of Federal systems. In this report, the 1710-1850 MHz band will be considered in two parts: the 1710-1755 MHz portion, and the 1755-1850 MHz portion. As noted above, the 1710-1755 MHz band was identified by NTIA to be reallocated and transferred to the FCC under OBRA-93 as a mixed-use band. The 1755-1850 MHz band is a vital national asset to support Federal operations, particularly national defense, the control of electrical power transmission, and law enforcement. The Federal use of the 1755-1850 MHz band can be categorized into several broad classes of systems, 1) tracking, telemetry, and commanding for Federal space systems, 2) medium-capacity, conventional fixed microwave communications systems, 3) military tactical radio relay (TRR) systems, 4) air combat training systems (ACTS), 5) precision guided munitions (PGMs), 6) high resolution airborne video data links, and various other aeronautical mobile applications, and 7) land mobile video functions such as robotics, surveillance, etc.
NTIA examined the Federal use of the 1710-1850 MHz band for possible accommodation of advanced mobile telecommunications systems, such as IMT-2000. To aid in NTIA’s evaluation of accommodating IMT-2000 services in the 1755-1850 MHz band, the DOD provided to NTIA on February 15, 2001, a report that detailed the electromagnetic compatibility (EMC) between major DOD systems in the 1755-1850 MHz band and IMT-2000 systems, relocation costs and operational impacts as a result of any potential DOD migration from the band, and an examination of time requirements should DOD systems move from the band. NTIA did not perform independent technical analyses on DOD systems. Data from those analyses furnished by the DOD in its final report were incorporated into this report.
If possible, sharing the spectrum would allow for a more efficient use of this resource than would relocating incumbent users. It is recognized that some systems will not be able to share with a nationwide build out of 3G mobile systems. These systems will have to be moved to another frequency band if accommodation is to occur.
General. This NTIA Final Report examines the feasibility of accommodating IMT-2000 systems by sharing the 1710-1850 MHz band with incumbent Federal users, or segmenting the band. In the 1755-1850 MHz band, predicted interference to both IMT-2000 and incumbent systems would preclude compatible operation at a large number of metropolitan areas and over large geographic areas of the country. Unacceptable operational restrictions would be required on DOD systems in order to mitigate the interference with IMT-2000 systems. Therefore, it was concluded that full-band sharing was not feasible.
This report also examines whether Federal agencies can fully vacate the 1755-1850 MHz band to accommodate IMT-2000 systems. The most optimistic estimates, based on funding being available in Fiscal Year 2002, indicate that all Federal agencies will be unable to fully vacate this band until well beyond the time lines established for this study (i.e., 2003, 2006, and 2010). The examination revealed that regardless of funding, vacating the band could not be accomplished for most DOD non-space systems until 2010 and beyond. Legacy space systems would require continued protected access to the 1761-1842 MHz band until 2017, and possibly as late as 2030 for some satellites. Migration prior to these dates would require premature satellite loss, which would have extremely serious implications to Federal agencies’ abilities to effectively accomplish their missions.
Moreover, for DOD systems, total relocation from any band requires alternate spectrum that is technically comparable, with the same degree of regulatory protection that currently exists in the 1755-1850 MHz band. NTIA has found, however, that comparable spectrum may not be available.
The DOD EMC analyses showed that all major DOD systems will encounter serious challenges in accommodating IMT-2000 systems, and could face significant operational restrictions in any frequency sharing situation.
Space Operations. Federal satellite control is an essential function and is authorized to use the 1761-1842 MHz portion of the band. This function could not be completely relocated until all satellites using this band have expired, which could be as late as 2030. The DOD analysis indicated that co-channel sharing between satellite control uplinks and transmitting IMT-2000 base stations would result in excessive interference to the uplink signal, and is not feasible due to the potential for harmful interference to satellite control signals at the orbiting satellites.
The DOD analysis showed that co-channel sharing with transmitting IMT-2000 mobile stations in a fully built-out scenario results in less interference to the uplink signals. The potential for sharing the satellite control uplinks with IMT-2000 mobile units seems to be technically feasible, and the potential interference is within the range of prudent risk management. Interference to IMT-2000 systems from satellite control station transmissions could be mitigated by either IMT-2000 systems operating outside of the interference distances calculated for each satellite control station, or some real-time means for the IMT-2000 system to avoid assigning channels on frequencies that satellite control stations are using.
Therefore, with regard to possible near-term use of the band for IMT-2000 systems, sharing considerations with the satellite control systems presents a fundamental go/no-go decision, since near-term replacement or changing frequencies in orbiting satellites is not possible. All satellites supported in this band use receivers that are set to specific channels and cannot be re-tuned after launch. The lifetimes of these satellites can exceed 10 years. Uplink sharing is further complicated by the fact that transportable satellite control stations will be operated at deployed locations when necessary to accomplish the satellite control mission. The 2025-2110 MHz band could possibly accommodate satellite control functions in the future. However, it would take several years to fund, develop, acquire, test, and qualify space flight hardware, and frequency allocations for the band would need to be revised via an FCC rulemaking process for space services that provides comparable regulatory protection.
The satellite control stations can potentially cause interference to co-channel IMT-2000 stations at significant distances, depending on the terrain surrounding the satellite control station. Near-worst-case interference distances in excess of 300 km were calculated using a smooth-Earth propagation model. Actual interference distances will generally be less because of terrain shielding.
Tactical Radio Relay Operations. Loss of significant spectrum to support TRR training would lead to the requirement for replacement of the military TRR systems. An examination of the spectrum below 3 GHz did not yield any available frequency band comparable to the 1710-1850 MHz band for accommodation of the DOD use of TRR and other DOD spectrum-dependent systems in support of test and training or large-scale military exercises. Therefore, lacking comparable spectrum, the TRR systems cannot be relocated.
Air Combat Training Operations and Precision Guided Munitions. For the ACTS, the 2010 time frame may allow for an accelerated Joint Tactical Combat Training System program to provide replacements for the current ACTS systems. Modifications to current ACTS systems could also be complete by that time. The point-to-point fixed links could be relocated to the 4400 MHz or 7/8 GHz bands. However, compatibility issues with incumbent systems in the air/ground alternate bands (2200-2290 MHz and 4400-4940 MHz bands) could prevent successful relocation of the air/ground links.
Under any frequency sharing scenario, ACTS and PGMs will require modifications to relocate to alternate bands. Sharing frequencies between these airborne systems and IMT-2000 is not feasible because interference can occur over very large areas.
Fixed Services. Conventional fixed systems are also a cause for concern because of their widespread use. NTIA concluded that general sharing of IMT-2000 operations with the current nationwide fixed service systems would not be feasible
Other Government Systems. Other systems operating in the band, such as PGMs, unmanned aerial vehicles, advanced data links, and electronic identification of friendly forces, were studied to determine if they could share with IMT-2000 systems, or be relocated. Generally, sharing was found to be problematic, and the systems would need to be re-designed to work in other frequency bands.
The DOD EMC analyses further indicated that the extensive use of the 1755-1850 MHz band by DOD, coupled with the projected build out of IMT-2000 systems, would make uncoordinated sharing with IMT-2000 systems infeasible. However, three sharing and segmentation options were considered in this report as shown below.
Option 1: In-Band Pairing. In this sharing option, the 1710-1850 MHz band is considered as divided into three segments, 1710-1755 MHz, 1755-1805 MHz, and 1805-1850 MHz. In this approach, mobile (handset) IMT-2000 units would share and transmit in the 1710-1755 MHz segment, the Federal Government would retain exclusive use of the 1755-1805 MHz segment, and the IMT-2000 base stations would share and transmit in the 1805-1850 MHz segment. This segmentation might make up to two 45-MHz segments available for IMT-2000 services (i.e., 1710-1755 MHz paired with 1805-1850 MHz), under certain conditions. IMT-2000 operators would coordinate their operations within protection areas, defined by separation distances from major Federal systems required to reduce mutual interference to an acceptable level. However, since both mobile and base stations transmit (and receive) in the 1710-1850 MHz band, simultaneous coordination of both base and mobile frequencies may be necessary. These factors, plus sharing satellite control uplinks with IMT-2000 base stations, would preclude sharing under these conditions. Since sharing was shown not to be feasible, this is not a viable option.
Option 2: Out-of-Band Pairing. A second sharing option would provide for IMT-2000 mobiles to share and transmit in the 1710-1790 MHz range, in phases, with the base stations transmitting in frequency bands above 2110 MHz, e.g., 2110-2150 MHz and 2160-2165 MHz. The Federal Government would retain exclusive use of the 1790-1850 MHz segment. This segmentation option would have three phases, the first phase allowing IMT-2000 mobile operations to share in the 1710-1755 MHz band, then adding shared use in the 1755-1780 MHz band, and finally in the 1780-1790 MHz band, if required. As described above, IMT-2000 mobile operators would coordinate their operations with DOD users whenever they operate within protection areas, which are defined by separation distances from major Federal systems that would reduce mutual interference to an acceptable level. These protection areas would be in addition to the current 16 protected sites, and would include satellite control sites. This coordination of the mobile terminals might be technically implemented in the IMT-2000 base stations by the receiving base station not assigning mobile stations to a channel that was occupied by a Federal user.
This option presents certain advantages compared to the in-band pairing option from an interference standpoint, because only half of the IMT-2000 system needs to be coordinated, and IMT-2000 base stations would not operate co-channel with satellite control uplinks. Co-channel sharing with mobiles shows less interference potential to the satellite uplink, and may be feasible. In this case, satellite control uplinks would share with IMT-2000 mobiles in the 1761-1790 MHz band. This option could, in the long-term, make up to 80 MHz available for mobiles in the 1710-1790 MHz band to be paired with equivalent spectrum in a higher frequency band. The alternatives to sharing would be for IMT-2000 services to be implemented in other frequency bands, or, Federal systems in the band segments required for IMT-2000 to be relocated to comparable spectrum. IMT-2000 operators would reimburse Federal operators if relocation, modification, or re-tuning of the systems is necessary. Essential Federal Government capabilities must be maintained.
Option 3: Out-of-Band Pairing & Federal Migration From Band. The third approach considers that the 1710-1755 MHz band might be vacated by Federal operations, in stages. IMT-2000 systems, paired with spectrum above 2100 MHz, would then have unrestricted operation nationwide. Until replacement systems are funded and deployed, the 16 protected areas would be replaced by new protected areas, selected to allow for full training on DOD systems in the 1710-1755 MHz band. When deployed, new DOD TRR equipment, designed to operate up to 2690 MHz, would then be authorized to operate in the new protected areas in 45 MHz of comparable replacement spectrum somewhere below 2690 MHz. As with any option that may necessitate the relocation of existing Federal users, reimbursement guidelines, appropriate time lines and access to comparable spectrum are issues that will need to be resolved.
In order to evaluate options associated with possible relocation of Federal systems to alternate frequency bands, a determination of estimated relocation costs, operational impacts, and time schedules for moving were developed. Estimated costs for DOD systems were submitted to NTIA in the DOD Final Report. Costs for Federal civil agencies’ systems were submitted in writing by each agency. Costs for DOD systems were submitted as "budget-year" amounts (called "then-year" dollars (TY$) in the DOD Final Report), while other Federal agencies’ costs are given in Fiscal Year 2002 (FY02) dollars. Direct addition of these amounts will yield an inconsistent value. A deflator factor of 1.102 was used to equate TY$ to FY02 dollars. NTIA has relied on the cost data furnished by the Federal agencies as being representative of estimated total system replacement costs, realizing that there are some unknown factors that will affect the final costs.
The total cost to relocate Federal operations from the 1755-1850 MHz band is estimated to be $4,640 million (FY02), if the time line specified by DOD and the other Federal agencies is accommodated and alternate spectrum is made available. Although all relocation options have an estimated total cost, this does not mean that relocation of all Federal systems is possible. For example, no adequate alternate spectrum was found for the DOD TRR system.
NTIA is developing rules for private sector reimbursement for relocating to other frequency bands Federal systems currently operating in certain frequency bands (including the 1710-1755 MHz band) identified for reallocation. This reimbursement process is similar in some respects to the procedures used in clearing the commercial PCS band. NTIA has released a Notice of Proposed Rulemaking, and is in the process of establishing rules for private sector reimbursement for relocating Federal systems. The procedures established by NTIA’s rulemaking will be used as a basis for reimbursement for the relocation of Federal systems, where necessary, from parts of the 1755-1850 MHz band.
Sharing Versus Options
Sharing is proposed for two options (Options 1 and 2). If sharing could be accomplished, the government reimbursement costs incurred would be minimal, since the responsibility for coordination would be borne by the commercial IMT-2000 service providers. However, under the condition that sharing is not feasible, total costs are presented for complete relocation of Federal systems. If some sharing is possible, then the costs would be less. These cost estimates are appropriate only as guidelines in determining what the final relocation expenses might be. Estimated costs are based on very specific assumptions and schedules. Departures from these assumptions would substantially change the cost of relocation. Some cost factors, such as final selection of alternative frequency bands, are unknown at this time, and could influence the final cost. The DOD indicated that under any circumstance they would not be able to vacate portions of the 1755-1850 MHz band until beyond 2010. Support in the 1755-1850 MHz band for Federal space assets would need to continue until at least 2017, and possibly until 2030 for some satellites.
Costs versus Options
Total estimated relocation costs in FY02 dollars for the three options as described in this report are as follows:
In implementing any of the options involving band segmentation, many Federal systems in the 1755-1850 MHz band would need to be either relocated to different frequency bands or modified to operate in the remaining portions of the band. Major performance, compatibility, funding, and regulatory issues would have to be thoroughly addressed before any relocation could begin. A major uncertainty with the concept of large-scale relocation is that critical issues regarding the costs, risks, and engineering efforts to assure the incumbent systems in the alternate bands are protected are not addressed. In the aggregate, this would be a complex, costly, and lengthy process. The major risk in relocating major national defense systems is the uncertainty of future successful mission accomplishment.
Specifically, there are several issues that must be resolved before any spectrum can be made available in the 1755-1850 MHz for reallocation, including continuity of essential government operations, interference, and regulatory protection of Federal Government systems during any migration period; assurance of comparable spectrum available to which Federal Government systems can relocate; and timely resolution of any regulatory actions necessary to make such spectrum available.
Note that the NDAA for Fiscal Year 1999 also requires that Federal Government agencies required to relocate or modify their radiocommunications systems to accommodate private sector use of the spectrum be reimbursed for the costs associated with such relocation or modification. NTIA is in the process of developing and implementing rules for reimbursement. These rules will be applicable to relocation costs associated with the 1710-1755 MHz band and any spectrum that is or would be reallocated in the 1755-1850 MHz band.
Further, with respect specifically to surrender of spectrum in which the DOD is a primary user, the NDAA for Fiscal Year 2000 also requires that:
"(A) the National Telecommunications and Information Administration, in consultation with the Federal Communications Commission, identifies and makes available to the Department for its primary use, if necessary, an alternative band or bands of frequencies as a replacement for the band to be so surrendered; and
(B) the Secretary of Commerce, the Secretary of Defense, and the Chairman of the Joint Chiefs of Staff jointly certify to the Committee on Armed Services and the Committee on Commerce, Science, and Transportation of the Senate, and the Committee on Armed Services and the Committee on Commerce of the House of Representatives, that such alternative band or bands provides comparable technical characteristics to restore essential military capability that will be lost as a result of the band of frequencies to be so surrendered."
NTIA finds that unrestricted sharing of the 1755-1850 MHz band is not feasible, and any other sharing options would require considerable coordination by IMT-2000 operators when operating in the presence of Federal systems. In the event of Federal relocation resulting from sharing/segmentation options, issues involving comparable spectrum, reimbursement, and the time required for Federal entities to either modify or replace equipment would need to be addressed.
Three sharing/segmentation options were examined for 3G accommodation. Option 1, which included in-band pairing and sharing with both IMT-2000 mobiles and base stations, was found not to be viable because of sharing difficulties. Option 2, which considered sharing and out-of-band pairing, was found to be on option that could be further considered, but sharing problems with some Federal systems remain to be solved. Option 3 considers migrating Federal users out of the 1710-1755 MHz band in the long-term, and pairing this with spectrum in the 2110-2150 MHz and 2160-2165 MHz bands. This option may be possible if, along with considerations of reimbursement and appropriate time lines, 45 MHz of comparable replacement spectrum can be allocated to Federal use to accommodate the military training requirements for TRR systems.