CHAPTER 2
SPECTRUM REQUIREMENTS
Spectrum Requirements Summary
The NTIA Requirements Study found that a total of 204 MHz will be needed for land mobile operations within the next 10 years. Of this amount, 119 MHz will be needed for systems such as cellular telephony, paging, specialized mobile radio, public safety and industrial, and conventional dispatch communications. The allocation of this spectrum to the various commercial functions, in general, would be left to market forces. Exceptionally, 50 MHz of this spectrum was identified specifically for public safety/industrial uses.
The remainder of the requirement, 85 MHz, would be to support the emerging ITS. Current plans call for access to approximately 75 MHz below 10 GHz, and 10 MHz between 10 GHz and 100 GHz. Experimental work for ITS communications is also being accomplished using five Federal channel pairs (a total of 50 kHz) in the 220-222 MHz band.
In addition, the NTIA Requirements Study concluded that the fixed service in the 3.7-4.2 GHz band could reasonably be expected to operate with 250 MHz less spectrum by 2004. While this spectrum may not be suitable for land mobile operations because of incompatibility with existing fixed service and television receive-only operations, it is possible that compatible services could be relocated to the 3.7-4.2 GHz band, freeing other spectrum that could be used for land mobile operations.
Current Land Mobile Services and Systems
The land mobile services currently operate in the VHF and UHF portions of the radio spectrum. TABLE 2-1 summarizes the bands that the various land mobile services are allocated. TABLE 2-1 was developed using information from the NTIA Manual and summarizes the land mobile service bands (primary) in the United States between 25 MHz and 2 GHz. Of the 319 MHz of spectrum between 25 MHz and 2 GHz allocated for land mobile use, 42 MHz (13 percent) is allocated for Federal use, while 277 MHz (87 percent) is for non-Federal use. Further, the Federal land mobile bands are allocated on a co-primary basis with the fixed service. That is, Federal mobile service operations in these bands are shared with Federal fixed service operations.
Major land mobile allocations appear in the VHF low band (25-50 MHz), VHF high band (138-174 MHz), the UHF bands (406.1-420 MHz, 450-512 MHz) and within the 800 and 900 MHz bands. As can be seen from TABLE 2-1, the majority of land mobile operations occur below 1 GHz and consist primarily of dispatch services. Recently, the FCC allocated the 1850-1910 and 1930-1990 MHz band for licensed PCS.
Band (MHz) Allocation Uses Remarks
25.01-25.07 non-Federal Dispatch Conventional, 25.21-25.33 non-Federal some non-Federal paging 26.175-26.480 non-Federal 27.41-27.54 non-Federal 29.7-29.8 non-Federal 30.00-30.56 Federal 30.56-32.00 non-Federal 32-33 Federal 33-34 non-Federal 34-35 Federal 35-36 non-Federal 36-37 Federal 37-38 non-Federal 38-39 Federal 39-40 non-Federal 40-42 Federal 42.0-46.6 non-Federal 46.6-47.0 Federal 47.00-49.6 non-Federal 49.6-50.0 Federal ___________________________________________________________________________ 138-144 Federal Dispatch Military 148.0-149.9 150.05-150.8 ____________________________________________________________________________ 150.8-156.2475 non-Federal Dispatch PLMR conventional 157.450-161.575 some paging 161.625-161.775 ____________________________________________________________________________ 162.0125-173.2 Federal Dispatch Most crowded band 173.2-173.4 non-Federal Dispatch Secondary basis 173.4-174.0 Federal Dispatch 220-222 Federal,non-Federal Dispatch Nationwide/local 406.1-420 Federal Dispatch Conventional and trunked 450-470 non-Federal Dispatch PLMR conventional and trunked 470-512 non-Federal Dispatch PLMR shared with UHF TV 806-821/851-866 non-Federal Dispatch,SMR PLMR conventional and trunked 821-824/866-869 non-Federal Dispatch Public safety only 824-849/869-894 non-Federal Cellular 896-901/935-940 non-Federal Dispatch,SMR PLMR conventional and trunked 929-930 non-Federal Paging 901-902,930-931,940-941 Federal,non-Federal Advanced paging Also called "Narrrowband PCS" 1850-1910,1930-1990 non-Federal Licensed PCS Deployment expected soon
Figure 2-1. Land mobile service allocations. 
Figure 2-1 shows the approximate amount of spectrum allocated to various land mobile services. Cellular and PCS allocations account for nearly 60 percent of the allocated land mobile spectrum. Many public safety organizations have indicated that the 23 MHz of spectrum allocated to the non-Federal public safety services is insufficient and that additional spectrum will be needed for basic voice dispatch and other current public safety spectrum needs.
The general consensus within the land mobile community is that the demand for land mobile services exceeds the amount of spectrum that is currently allocated in many geographic areas. License data indicates that the number of private land mobile transmitters is increasing at a rate of nearly eight percent per year.[Endnote (EN) #1] Further, Federal frequency assignment records show that Federal land mobile assignments are increasing as much as 12 percent per year.[EN #2]
To provide relief, significant effort is being focused on technology as a means to increase spectrum efficiency and capacity. As was discussed earlier, both NTIA and the FCC have embarked on ambitious plans to narrowband their land mobile bands. The cellular industry is implementing digital multiple access techniques that will further increase spectrum efficiency. The public safety community formed the Association of Public-Safety Communications Officials-International, Inc. (APCO) Project 25 to develop standards for equipment which will ensure a graceful migration between techniques and intercommunications between the products of different manufacturers. These systems will use 12.5-kHz channels, with a full range of digital data and vocoder features, including encryption.
NTIA noted in the NTIA Requirements Study that although technology will provide some relief, it is no panacea for the current congestion that the land mobile services are experiencing. This congestion is particularly heavy in major metropolitan areas where, according to APCO, it is becoming increasingly difficult, if not impossible, to find enough channels to satisfy the demand. This is also true for Federal operations.
To show the degree of usage of a frequency band, NTIA developed the Spectrum Use Measure (SUM) Model.[EN #3] The SUM is a computer model that uses either the Government Master File (GMF) or FCC data base for input data. The SUM provides a technique for estimating the extent of the use of the radio frequency spectrum in a given frequency band. An output of the SUM model used herein is the Spectrum Use Factor (SUF). SUF measures the probability that spectrum is not available for additional use in a given location because of existing users. The SUF is a value ranging from 0 to 1 that represents the percent of spectrum resources used in a particular location, zero representing the least spectrum resources used. For example, a SUF value greater than "0.8" indicates that greater than 80 percent of spectrum resources are used in that particular location.
Figures 2-2, 2-3, 2-4, 2-5, and 2-6 illustrate areas of the United States with various ranges of SUF values for the 150.8-174 MHz, 162-174 MHz, 450-470 MHz, 851-866 MHz, and 866-869 MHz bands, respectively. Data used to generate these figures was extracted from the GMF or the FCC license database, which were current as of July 1995.
It should be noted that the SUF figures provided do not reflect records whose latitude and longitude were not specified, aeronautical stations, fixed assignments, or experimental and nationwide assignments. Therefore, the bands are generally more heavily used than indicated in the SUF plots. Nationwide assignments are particularly important for law enforcement activities for the Departments of Justice and Treasury. SUF values of "0.8" and greater indicate that the bands are currently congested in these urban areas.
The SUM program uses data from computer files for the analysis. Only stations with land mobile station classes were used for the analysis. Frequency bands containing other allocations, such as fixed, will show a lower station density on the SUF plots than actually exists. Any data file with missing data, particularly latitude and longitude data, will be ignored. Because data files often contain errors or missing data, this results in plots that generally understate the actual density of station operations. However, a relative sense of station density across the nation can be obtained from these plots.
Figure 2-2 is the SUF plot for the frequency ranges 150.8-156.2475 MHz, 157.45-161.575 MHz, 161.625-161.775 MHz, and 173.2-173.4 MH z (labeled 150.8-174.0 MHz). FCC license data was used for this plot and it shows non-Federal Government use only. It should be noted that the fixed service is also allocated in the 172.3-173.4 MHz band. Only station locations for the land mobile service were plotted. The New York City area shows SUF factor values above 0.8 and is considered to be congested. The area around Las Vegas, Nevada contains factor values of 0.6 to 0.8 and is considered to have heavy usage. Other areas are below 0.6 and considered to show light to medium usage.
Figure 2-3 is the SUF plot for the frequency ranges 162.0125-173.2 MHz and 173.4-174.0 MHz (labeled 162.0 to 174.0 MHz). The Government Master File data was used for this plot and shows Federal Government use only. It should be noted that the Federal allocations for these ranges include both fixed and mobile allocations, with many fixed assignments. Again, only land mobile station classes were selected for plotting, resulting in a lower density of assignments than if all assignments, including other mobile, were plotted. The plot shows that in many urban areas indicated by the 0.6-0.8 color that heavy use is being made of the band. Because of nationwide assignments, these SUF values should not be compared with plots using FCC data.
Figure 2-4 is the SUF plot for the frequency range 450.0-470.0 MHz. FCC license data was used for this plot. The plot shows SUF factors above 0.8 for large areas of the country, particularly the eastern half of the United States and the three westernmost states, indicating that spectrum is congested.
Figure 2-5 is the SUF plot for the 851.0-866.0 MHz band. FCC license data was used for the plot. This band is allocated for conventional and trunked land mobile systems, and is used by the base stations for the systems. SUF values above 0.8 are pervasive over much of the country and indicate the spectrum is congested.
Figure 2-6 is the SUF plot for the 866.0-869.0 MHz public safety band. FCC license data was used for this plot. This is a relatively new band for public safety operations, but shows that the band is congested in some of the major urban centers. SUF values above 0.8 are shown for areas including New York City, Chicago, Dallas/Fort Worth, Los Angeles, San Francisco, and southeastern Florida.
Figure 2-2. Spectrum Use Factor for the 150.8 - 174.0 MHz band. 
Figure 2-3. Spectrum Use Factor for the 162.0 - 174.0 MHz band. 
Figure 2-4. Spectrum Use Factor for the 450.0 - 470.0 MHz band. 
Figure 2-5. Spectrum Use Factor for the 851.0 - 866.0 MHz band. 
Figure 2-6. Spectrum Use Factor for the 866.0 - 869.0 MHz band. 
Public Safety Services
The public safety community, both Federal and non-Federal, is one of the most important users of the radio spectrum. Public safety services, for example, provide law enforcement, fire suppression, and emergency medical treatment for citizens of the United States during natural and man-made disasters. Major natural disasters occur on a continuing basis. Major disasters such as the recent hurricanes Andrew and Hugo, the San Francisco earthquake, and the California wildfires and Mississippi Valley floods have required the deployment of thousands of radios for both the Federal and non-Federal public safety agencies. In addition to natural disasters, major crises such as Waco, Texas, and the bombings of the World Trade Center and the Federal Building in Oklahoma have shown the importance of public safety communications. Situations like these require cooperation and coordination between the Federal and non-Federal public safety communities. At the Oklahoma City bombing, the need for common public safety communications was evident when public safety groups' two-way radios, which were all on different frequencies, could not interoperate.[EN #4]
Sufficient mobile communication capacity for agencies charged with protecting the public welfare is of critical importance to the overall well-being of the nation. Wireless communications provides a vital component in the nation's public safety and emergency medical infrastructure. Agencies involved in the protection of life and property are able to do their jobs effectively and efficiently only by making extensive use of a wide array of wireless communication options available to them. Full use of these options requires that sufficient spectrum capacity be available and that spectrum use be well planned and coordinated to assure that the diverse needs of the public safety entities can be satisfied. Today, the majority of public safety communications tends to be primarily voice and data communications using a single frequency or a pair of frequencies. In the near future, the content of public safety communications will include not just voice, but also fingerprints, mug shots, building diagrams, slow and full motion video, transaction/decision processing data, and a host of other high speed data applications that will require wider bandwidths than conventional communications.
A critical element of public safety communications systems is the need to accommodate peaks in service demand that occur during multiple emergencies. There must be sufficient capacity to handle not only normal day-to-day communications needs, but also large scale emergencies such as civil disturbances, storms, major fires, earthquakes, and other natural and man-made disasters. In addition, many public safety services require communications with privacy. The monitoring of clear communications by the general public, the news media, foreign intelligence agents, and criminals has disrupted investigations and caused life-threatening situations for law enforcement personnel and innocent victims. Digital encryption, spread spectrum and other techniques are now utilized to assure transmissions are not compromised.
In recent years, there has been increasing and significant attention being paid to the operational, technical and spectrum needs of Federal, State, and local public safety entities. Within Congress and the Administration, the desire to address these needs has become critical recently, as evidenced by the recent House Appropriations hearings. At those hearings, Congress directed NTIA and the FCC to jointly develop plans to satisfy the needs of Federal, State, and local public safety agencies. In response, NTIA cooperated with the FCC, Federal, State, and local public safety organizations, to establish a joint Public Safety Wireless Advisory Committee (PSWAC) as a means of providing user-direct input to the development of a National Public Safety Plan. Established in September 1995, the PSWAC will develop, within a 12-month period, recommendations to NTIA and the FCC, forming the basis for regulatory action to meet those needs.
The PSWAC consists of a Steering Committee and five Subcommittees that will address various aspects of public safety operations. The Subcommittee topics are (1) Operational Requirements, (2) Interoperability, (3) Technology, (4) Transition, and (5) Spectrum Requirements.
In March 1994, the Federal Law Enforcement Wireless Users Group, co-chaired by the FBI and the Secret Service, was formally chartered and tasked with the research and planning for a national law enforcement and public safety network. Its mission is to provide law enforcement and public safety an integrated wireless/wireline network that meets the functional requirements of the user community. As envisioned, the network will incorporate spectrally efficient technologies, support interoperability, and be secure. Network planning and development will be sensitive to individual agency issues such as priorities and privacy, will provide virtual autonomy and non-interfering operations, and will include flexibility to expand and extent capabilities. Cooperative and coordinated system development efforts between multiple agencies will relieve the effects of diminishing resources such as funding and radio spectrum and will result in numerous cost and quality of service advantages.
Established in 1989, APCO Project 25 is a joint Federal/State/local effort to set common technical standards ( a suite of standards) for VHF/UHF radio systems, hand-held and base, among all public safety communicators, including Federal agencies. Project 25 conforming radios will use up-to-date digital modulation to reduce bandwidth, increase communication range and provide for several levels of digital security and layered interoperability among service providers, while providing backward compatibility with analog FM systems. As the standard is implemented, public safety communication bandwidths will shrink from today's 25 kHz (analog FM), to 12.5 kHz (first-generation Project 25 digital voice systems), to an eventual 6.25 kHz (second-generation Project 25 digital). Also Project 25, in setting common standards, will allow every manufacturer to produce compatible radios, increasing competition, and bring down prices.
Intelligent Transportation System (ITS)
The Congress established as a national priority the implementation of a nationwide Intelligent Vehicle-Highway infrastructure called the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). Among other goals, Congress clearly articulated its expectation that ITS services and technologies would save lives and improve traffic safety, reduce traffic congestion, improve environmental quality in non-attainment areas under the Clean Air Act and enhance mobility and economic productivity.
This intermodal concept is known as the ITS and is an emerging user of land mobile services. Since the passage of ISTEA, much work has been completed looking toward attainment of the many benefits of nationwide deployment of ITS technologies recognized by Congress. For its part, ITS AMERICA, which serves as a utilized Federal Advisory Committee to the United States Department of Transportation (DOT), has worked in concert with many private and public sector parties in preparing an ITS National Program Plan[EN #5] for the deployment of ITS user services in the United States.
ITS will employ various types of radiocommunications systems within different radio services aimed at providing for a safer and more efficient future transportation infrastructure. The next five years will see the research and development, evaluation, and operational testing of various ITS projects applying modern telecommunications, location, and control technologies. The DOT and ITS AMERICA have indicated that access to additional spectrum will be required to satisfy the spectrum requirements of the ITS. Current estimates for ITS spectrum requirements include both radiocommunications services and radar. Preliminary estimates for land mobile radiocommunications requirements include the need for access to 75 MHz below 10 GHz, and 10 MHz above 40 GHz. ITS also has additional spectrum requirements for collision-avoidance radar systems that can be accommodated in current radiolocation bands above 40 GHz.
ITS AMERICA has identified key spectrum issues and trends that need further consideration. Telecommunications will be the backbone of ITS, and wireless communications will play a significant role in satisfying the ITS telecommunications requirements. ITS, where practical, will use existing services, such as cellular telephony, PCS and mobile-satellite services for the communications links. Where these existing services are not appropriate, ITS services will operate in the 902-928 MHz band and on five frequency pairs in the 220-222 MHz band. The 902-928 MHz band has become very congested and is the subject of numerous FCC rulemakings to resolve growing problems. Some of the newer electronic toll tag systems have moved up to the 2450 MHz band, where certain European Electronic Toll and Traffic Management (ETTM) systems operate. Because of competing requirements at these frequencies, use of the 5850-5925 MHz frequency band has been suggested for future growth and international interoperability. The allocation of spectrum for ITS services is of paramount importance to the ITS program in the United States.
Although the overall strategy of the ITS program is to make use of existing communications services, there are some critical safety and warning functions that will require dedicated spectrum. The initiatives underway that are aimed at identifying and acquiring radio frequencies for ITS are concentrating on these dedicated spectrum issues. The spectrum requirements are condensed into four main areas: (1) broadcast-type communications (one way); (2) short-range communications, including Location and Monitoring Services (LMS) and ETTM; (3) medium-to long-range communications; and (4) communications suitable for wireline services (i.e., not requiring mobile connections). More detail on spectrum requirements for the four main communications areas and the draft spectrum requirements matrix was presented in a paper presented by the United States in Paris, France, at the December 1994 ITS International Conference.[EN #6]
Frequency bands being considered for expansion of services presently carried out in the 902-928 MHz band are centered around 2400 MHz and 5800 MHz. The technical choice of frequency band is a function of area coverage, existing and developing technology and cost effectiveness.
ITS AMERICA formed a national ITS Communications Task Force in 1993 to further define the required spectrum. Participation in the task force was from the public, private and academic sectors. As a result of input from the task force, the DOT Federal Highway Administration (FHWA)has requested spectrum certification from the Interdepartment Radio Advisory Committee's (IRAC) Spectrum Planning Subcommittee (IRAC/SPS).[EN #7] This request includes access to 75 MHz of spectrum in the 5850-5925 MHz band for ITS experimental field tests until the year 2010.[EN #8] One purpose of the field tests will be to verify the ability of fixed and mobile radios operating in this band to support a range of ITS communications functions such as toll collection, safety and warning, and vehicle-location. The areas of operation for these field tests are in and around 23 major U.S. cities. This request for spectrum usage would be in addition to current ITS operations in the 902-928 MHz and 2400-2500 MHz bands, and would provide for further growth. The FHWA has an on-going experimental program for narrowband operations using five Federal Government frequency pairs in the 220-222 MHz band and has stated they may need additional frequency pairs. The requirement for the 10 MHz above 10 GHz for land mobile service was further defined by DOT/FHWA as intended to support a data link and should be above 40 GHz. This data link is to operate with a radar system referred to as the "vehicle collision avoidance system" (VCAS). VCAS is envisioned to consist of two different services, the radar itself, and a fixed and mobile high-capacity, short-range data link that would be used for automated vehicle control (platooning), and for the coordination of evasive action between vehicles that are on a collision course.[EN #9]
ENDNOTES
1. Richard J. Orsulak, William D. Speights, Ernesto A. Cerezo, Robert C. Wilson, U.S. Department of Commerce, NTIA TM 94-160, National Land Mobile Spectrum Requirements, January 1994 at 116.
2. Id. at 55.
3. Mayher, R.J., R.H. Haines, et. al., The SUM Data Base: A New Measure of Spectrum Use, U.S. Department of Commerce, NTIA TR 88-236, August 1988; Robin H. Haines, Steven E. Litts, U.S. Department of Commerce, NTIA TR 89-248, The SUM Land Mobile Model: Application of the Spectrum Use Measure to the Land Mobile Service, September 1989.
4. Linda Kay Sakelaris, Oklahoma rescuers use cellular when 2-way can't communicate, RCR, May 8, 1995, at 3.
5. U.S. Department of Transportation, National ITS Plan, Program Plan Intelligent Transportation Systems, March 1995.
6. U.S. Department of Transportation, Radio Frequency Spectrum Acquisition and Coordination for North American Intelligent Transportation Systems (ITS), U.S. Paper to ITS World Conference, Paris, France, December 2, 1994
7. OMB in their Circular A-11 established a policy requiring Executive Departments and Agencies to secure assurance of spectrum support from NTIA prior to the development or procurement of major communications-electronics systems. The certification of spectrum support and the conditions under which such support is granted is obtained through the system review procedures, contained in Chapter 10 of the NTIA Manual.
8. Spectrum Planning Subcommittee (SPS) Submission SPS-10448, Intelligent Transportation System (ITS) in the 5850-5925 MHz Band.
9. Comments of DOT to the FCC in Amendment of Parts 2 and 15 of the Commission's Rules to Permit Use of Radio Frequencies Above 40 GHz for New Radio Applications, Notice of Proposed Rule Making, ET Docket No. 94-124, 59 Fed Reg. 61304 (1994).
Proceed to Chapter 3: Spectrum Availability
Return to Table of Contents.