Long-term spectrum planning is critical to the efficient development of spectrum-dependent telecommunications services. Forecasting the demand for these services and allocating adequate spectrum for radio services in advance will assure that these telecommunication services are provided in a timely and efficient manner. Further, early identification of spectrum for an intended use gives manufacturers adequate lead time to design and manufacture equipment for the planned frequency bands, and provides the lead time demanded by Federal budget cycles.
The National Telecommunications and Information Administration (NTIA), under a mandate from Congress to develop long-range spectrum plans, initiated the Strategic Spectrum Planning Program. As part of this long-term planning effort, NTIA released a report, U.S. National Spectrum Requirements: Projections and Trends (hereinafter NTIA Requirements Study) in April 1995 addressing all radio services, and found that eight of these services needed access to additional spectrum in order to satisfy user requirements to the year 2004.
While all radio services are important to the nation, the most immediate critical need for spectrum is for the land mobile services, including public safety and the Intelligent Transportation System. Current land mobile spectrum is already congested in many urban areas, and the number of systems is expected to double in the next 10 years. Additionally, the demand for land mobile services is driven by societal needs, such as demands for increased public safety services, the increased mobility of business users and consumers, and the emerging advanced transportation systems. All these factors indicate that demand for mobile spectrum will continue to increase. This report focuses only on these land mobile spectrum requirements; spectrum requirements of the other radio services will be addressed in future efforts.
This report examines the additional spectrum requirements for the land mobile service previously identified by NTIA. The report develops four general options for increasing spectrum availability, investigates the allocated spectrum below 3 GHz for suitable land mobile spectrum, and identifies a number of frequency bands that could satisfy many of the land mobile spectrum requirements.
Land mobile services are used by both the private sector and the Federal Government. Land mobile services include various categories such as commercial mobile radio services, cellular telephony, personal communications services (PCS), industrial and business mobile services, Federal agencies' vehicular and hand-held units, State and local public safety services, and Federal law enforcement mobile units.
Land Mobile Spectrum Needs
The NTIA Requirements Study found that 204 MHz of spectrum is required for land mobile services in the next 10 years. Of this amount, NTIA forecast that 50 MHz would be required for new advanced private land mobile services, including public safety and industrial uses. The Intelligent Transportation System was forecast as needing 85 MHz, which included short-range information exchange systems and vehicular collision-avoidance data links. Commercial users and other private and Federal land mobile systems accounted for the remaining 69 MHz.
Analysis of current land mobile bands using computer-aided calculations showed these bands to be congested in the larger urban areas. For dispatch-type operations, which are generally doubling every 10 years, the spectrum shortfall will be mostly relieved by the implementation of narrowband or multiple-access, spectrum-efficient technologies. Both NTIA and the Federal Communications Commission (FCC) have programs to implement these technologies.
Increasing Land Mobile Efficiency
Both NTIA and the FCC are involved in proceedings and efforts to increase the efficiency of spectrum used in the land mobile services. NTIA has submitted to Congress its plan to improve the efficiency of Federal land mobile operations and has identified 235 MHz of Federal spectrum for transfer to the FCC. This spectrum transfer was required by Title VI of the Omnibus Budget Reconciliation Act of 1993. Ninety-five megahertz of this spectrum has already been transferred to the FCC for private use; the remaining spectrum will be vacated by Federal users.
The FCC has also undertaken related measures as part of its spectrum planning efforts, including implementing narrowband technology in the land mobile bands between 72 MHz and 512 MHz, allowing public safety communications on an unused ultra high frequency (UHF) TV channel in New York City, and permitting sharing of very high frequency (VHF) maritime channels with land mobile users that are geographically separated.
When spectrum demands exceed available allocations, there is a limited set of options possible to satisfy the demand for spectrum access. For the purposes of this study, four options for additional spectrum access were addressed. These options are: (1) utilize higher frequencies (above 20 GHz); (2) reaccommodate incumbent spectrum users to other frequency bands; (3) make more efficient use of current frequency allocations by use of advanced technologies; and (4) use non-spectrum technologies such as fiber optic cable instead of radio spectrum.
Generally, spectrum options for land mobile were limited to those bands below 3 GHz because of propagation considerations. Nevertheless, spectrum requirements for the Intelligent Transportation System and for wide-band video could be satisfied in bands above 3 GHz.
With respect to spectrum that could be made available for allocation to land mobile services, the primary focus is on those frequency bands recently transferred from Federal control to the FCC, because these bands will be mostly vacated by current Federal users. Additionally, spectrum in the current VHF television broadcast band that may become available subsequent to the introduction of advanced television services is included in this report.
For the purposes of spectrum planning, the frequency bands outlined below should be considered for satisfying future land mobile spectrum requirements. Those bands transferred to the FCC from Federal use will be available as detailed in the NTIA Final Reallocation Report. Portions of the VHF television band (174-216 MHz) listed below may only become available for other uses at a time beyond the 10-year period of our spectrum requirement forecast. This band is included here for long-term planning purposes; however, unforeseen situations could occur that could preclude its use. Increased use of vacant UHF television channels is encouraged, but will depend on the degree of implementation of over-the-air advanced television services in urban areas.
Spectrum options that are identified for possible future land mobile use are listed below.
Spectrum Availability and Planning Options
Spectrum Options . . . . . . . . . . Land Mobile Use(s)
174 - 216 MHz Conventional or Trunked Dispatch, Paging 1390 - 1400 MHz Wide Area Land Mobile 1427 - 1432 MHz Wide Area Land Mobile 1670 - 1675 MHz Wide Area Land Mobile 1710 -1755 MHz Wide Area and Wide Bandwidth Public Safety, Industrial & Business 2300 - 2310 MHz Wide Area Land Mobile 4635 - 4685 MHz Multiple uses, including Mobile Video 5850 - 5925 MHz Intelligent Transportation System Ten megahertz within one of the following bands: 49.7-50.2 GHz 50.4-51.4 GHz 68.9-72.7 GHz 168.0-168.3 GHz Intelligent Transportation System
The report also concluded that public safety users should consider implementing shared Federal/non-Federal multisite trunked communications systems such as that being studied for the State of Colorado, or wide-area systems using cellular or PCS technology for future narrowband operations. This approach will also relieve any near-term spectrum shortfall occurring during the transition to narrowband technologies. Public safety and industrial requirements for full-motion video may be satisfied in portions of the 4635-4685 MHz band.
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