As was noted in the NTIA Requirements Study, the land mobile services, including public safety, are the most in need of additional spectrum. This need results largely from the rapid growth in cellular and paging services, and the anticipated growth in PCS and public safety operations. APCO suggests that the growth in demand for such public safety services can be attributed to the increasing reliance on radio communications by public safety personnel, increases in crime, and the anticipated growth in the number of public safety personnel.[Endnote (EN) #1]
In the NTIA Requirements Study, an estimate of additional spectrum needed for the land mobile services was developed that included projected service needs, the effect of new technology, and the conversion rates of current systems to newer, more efficient technology.[EN #2] In that analysis of spectrum requirements, it was assumed that several of the mobile services are substitutes for each other (for example, cellular telephony, enhanced specialized mobile radio services, and some PCS services may be similar). Therefore, since this commonality of telecommunication offerings tend to blur the distinction between discrete services, the spectrum estimate for land mobile services was presented based on an aggregate user base, rather than on individual service offerings. NTIA estimated the additional spectrum requirement for these services, including public safety services, but excluding the Intelligent Transportation System (ITS), to be an additional 119 MHz. NTIA identified a requirement for an additional 75 MHz below 10 GHz and 10 MHz between 10 GHz and 100 GHz for ITS. NTIA agrees that additional spectrum is required for public safety services, including advanced wireless services such as transaction/decision processing, facsimile, snapshot, and slow and full motion video.
Having identified the future spectrum requirements for the land mobile services, the next step in the strategic spectrum planning process is to identify the spectrum that could satisfy those requirements. Identification of spectrum requirements is not sufficient for a spectrum management process that must ensure that spectrum is efficiently allocated for the constantly evolving radio spectrum needs.
The land mobile services currently operate in frequency bands from the VHF low band (25-50 MHz) up to 1 GHz. However, system performance in the VHF low bands tends to be particularly erratic. Transmissions that normally provide adequate signal strength over dozens of kilometers will at times skip hundreds or thousands of kilometers, thus rendering this band less desirable for land mobile use than bands located higher in the spectrum. The VHF high bands and UHF bands are more appealing due to lower noise and more reliable propagation properties. Recently, the FCC allocated the 2 GHz band for emerging land mobile services, i.e., PCS, thus extending the spectrum for non-Federal land mobile services. At present, silicon semi-conductor technology provides low-cost devices at operating frequencies up to about 2500 MHz.
Prior to the PCS allocation, the FCC noted in a report that 3 GHz posed an effective upper limit for mobile allocations.[EN #3] The FCC indicated that state-of-the-art technology for compact, light-weight portable, electronic components is generally limited to frequencies below 3 GHz. Many of the consumer-oriented and commercial products employing emerging mobile technologies will be used in urban areas, where radio coverage is increased as a result of multipath reflections. This allows radio signals to reach around buildings where a direct path cannot be maintained. Radio waves in the spectrum between 1 and 3 GHz have shown this capability, allowing emerging technologies to take advantage of the multipath benefits in urban environments.[EN #4]
Taking into consideration the less desirable propagation characteristics offered in the VHF low band, and an upper limit imposed by less desirable propagation and other technical constraints, our investigation will be generally limited to the frequency range between 100 MHz and 3 GHz to find the spectrum necessary to satisfy the land mobile requirements, excluding ITS. Of particular interest are those portions of spectrum below 3 GHz transferred from the Federal Government to the FCC, and a portion of the VHF broadcast TV spectrum. No attempt was made in this study to develop statistical data or to show general spectrum usage, spectrum availability, or band capacity. Rather, the study focused on spectrum that would become available in the next 10 years or immediately thereafter as a result of spectrum transfers, new technology implementation, and spectrum reallocation. Computer analysis of four current land mobile bands was accomplished to show current congestion in major urban areas.
Spectrum Management Options for Increased Spectrum Availability
Additional spectrum cannot be produced or discovered. We can only use the spectrum that current technology permits, and we must use it as efficiently as practicable. When spectrum demands exceed available allocations, there are a limited number of options possible to satisfy the demand for spectrum access. For the purposes of this study, four general options for additional spectrum access are discussed in the following paragraphs. These options can be invoked singularly or in combination.
Option 1: Make More Efficient Use of Current Allocations. The demand for spectrum is usually not for spectrum per se, it is rather a demand for increased communications capacity, which translates into more spectrum if the same technology is used. An equivalent to additional spectrum is, therefore, an increase in capacity using the same spectrum. Advanced technology, such as time division multiple access (TDMA) and code division multiple access (CDMA) has been demonstrated to increase capacity of conventional land mobile systems by factors of 3 to 20. Sectored antennas can also increase the spectrum efficiency of systems within land mobile operating areas.[EN #5] Where appropriate, decreasing the channel bandwidths and using automated frequency selection systems will also improve the efficiency of spectrum use.[EN #6]
The efficiency of an allocated block of spectrum can often be increased by the sharing of the block by an additional radio service. Many frequency blocks currently have two or more radio services allocated. Electromagnetic compatibility studies would need to be made to ensure that additional usage by another radio service would be compatible with the existing service(s), and would not lead to excessive congestion.[EN #7] In addition, there are other spectrum sharing considerations, such as the unique requirements of the safety services, economics, and the benefits to the public. Examples of recent sharing include the use of UHF TV Channel 16 in New York City for public safety communications, and the sharing of VHF maritime mobile channels with land mobile users.
Option 2: Reaccommodate Incumbent Spectrum Users. In certain circumstances, it may be feasible to reaccommodate spectrum users in one frequency band within another, or in a non-spectrum dependent medium, in order to clear the band for high-density systems. The FCC has taken this approach in the introduction of the PCS in the 2 GHz band. Current fixed microwave systems in this band will either be moved to other frequency bands, or be converted to fiber optic systems. PCS providers will provide funds to move incumbent fixed service systems. Without reimbursements, the incumbent users would have a very difficult time relocating.
Recent legislation has required the transfer of Federal spectrum to the FCC. With some exceptions, Federal frequency assignments in the bands transferred to the FCC will be withdrawn within a given time period. The affected Federal systems will be reaccommodated within other portions of these bands, or to other bands which have suitable and sufficient spectrum available. The availability of funding for this transition will determine the timing of the Federal movement to a large degree.
Option 3: Use Other (non-spectrum) Technologies. The relative advantages of spectrum-dependent systems and wireline[EN #8] systems are changing. Long-haul microwave systems are being converted to fiber optic to take advantage of fiber's higher capacity. The introduction of market-place forces has the potential to drive users to substitute non-spectrum using technologies for spectrum using technologies. Recent spectrum auctions indicate that society places a high economic value on spectrum. The rate at which current users substitute away from spectrum-using technologies will increase as market-place forces are incorporated into spectrum management. However, the option of using spectrum only for systems that cannot operate in a wired environment, such as mobile services, must be considered in a socioeconomic context as well as in a technical one.
Option 4: Utilize Higher Frequencies. Recent technological advances have made the spectrum above 20 GHz more usable for radio services. Extensive Federal Government research and development activities were responsible for developing radio applications for these bands primarily for space and military uses. However, much of this technology has been transferred to the private sector, encouraging the manufacturing of off-the-shelf components and systems that operate to 100 GHz. New radiocommunications systems that can operate within the constraints of this spectrum can now be accommodated, and similar systems currently operating in the lower bands could be reaccommodated above 20 GHz. Although this option applies primarily to the fixed services, limited land mobile use is possible.
Reallocated Federal Spectrum
Title VI of the Omnibus Budget Reconciliation Act of 1993 required the Secretary of Commerce to transfer from the spectrum allocated for Federal use, an aggregate of at least 200 MHz below 5 GHz for allocation by the FCC to non-Federal users. As a result, NTIA, on behalf of the Secretary of Commerce, identified 235 MHz to be reallocated to the private sector.[EN #9]
NTIA has identified 12 bands to be reallocated for either exclusive non-Federal use or for mixed Federal/non-Federal use, 9 bands of which are below 3 GHz. Reallocation of two of the bands below 3 GHz, the 2390-2400 MHz and 2402-2417 MHz, was completed in August 1994. Unlicensed PCS devices, including wireless networking and data transfer systems, will operate in the 2390-2400 MHz band. Other unlicensed devices and services, such as cordless telephones, security alarms, and utility metering devices will use the 2402-2417 MHz band.[EN #10] Additionally, the 2400-2402 MHz and 2417-2450 MHz bands are included for reallocation. The principal uses of these bands are industrial, scientific, and medical (ISM) devices, the amateur services, and unlicensed devices authorized under FCC Part 15 Rules. NTIA anticipates that some of the additional land mobile spectrum requirements could be satisfied in these bands allocated for unlicensed device operations.
The remaining bands below 3 GHz as identified in the final reallocation report are summarized below.
1390-1400 MHz. Currently, this band is used by long-range air defense radars, air traffic control facilities, military test range telemetry links, tactical radio relays, and radio astronomy. NTIA has indicated that this band has potential for new non-Federal fixed, mobile, and radiolocation communications technologies and applications.
NTIA notes, however, that high-powered Federal Aviation Administration (FAA) and Department of Defense (DOD) radars will continue to operate in the lower adjacent band, and important radio astronomy observations must continue within the band, making this band more appropriate for terrestrial-based services. Reallocating this band for exclusive non-Federal use would require that:
Transfer of this band is scheduled for 1999 to permit satisfaction of these conditions and completion of Federal reaccommodation efforts. Federal operations at 17 sites will continue for 14 years.[EN #11]
Comments on the FCC Notice of Inquiry (NOI) [EN #12] submitted by the National Association of Business and Educational Radio state that the 1390-1400 MHz band segment could be of some limited use for non-Federal applications.[EN #13]
1427-1432 MHz. This band is used by military tactical radio relay communications and military test range aeronautical telemetry and telecommand systems. The NTIA Final Reallocation Report indicated that the band has potential for new non-Federal fixed and mobile communications technologies and applications. In order to protect sensitive radio astronomy observations in the adjacent band, reallocation for airborne or space-to-Earth communications should be avoided.
Reallocation of this band for non-Federal use is scheduled for 1999 to permit the orderly phase-out of radio relay communications equipment, the procurement of replacement equipment, and the engineering of associated network systems. In addition, essential military airborne operations at 14 sites will be continued for 9 years.[EN #14]
In their comments to the NTIA Final Reallocation Report, Motorola and the Telecommunications Industry Association (TIA) representatives indicated that limited commercial applications in this band are feasible.[EN #15]
1670-1675 MHz. This band is used by meteorological aids systems that will have to be redesigned or replaced. The NTIA Final Reallocation Report indicated that the band has potential for new non-Federal fixed or mobile communications. In order to protect sensitive radio astronomy observations in the adjacent-band, reallocation for airborne or space-to-Earth communications should be avoided. Thus, terrestrial-based services would be appropriate.
Reallocation of this band is scheduled in 1999 to permit design and procurement of replacement equipment for meteorological radiosonde systems. However, non-Federal use at a limited number of sites that are engineered to be fully compatible with all Federal operations could be given immediate consider- ation. Reallocation also requires continued protection of two important meteorological-satellite service earth stations.
In their comments to the NTIA Final Reallocation Report, Motorola and TIA representatives indicated that limited commercial applications in this band are feasible.[EN #16]
1710-1755 MHz. This band is currently used extensively for Federal fixed point-to-point microwave communications, military tactical radio relay, and airborne telemetry systems. The NTIA Final Reallocation Report indicated that the band has potential for new non-Federal fixed and mobile communications services.
Reallocation of this band is scheduled for 2004 to provide for the orderly phase-out of existing Federal systems, the design and procurement of replacement equipment, and associated systems engineering. However, recognizing the needs of non-Federal users for spectrum, especially in major urban areas, reallocation of the band in 1999 may be possible for the 25 largest U.S. cities,[EN #17] provided that:
The reimbursement could be in the form of direct reimbursement of costs to the Federal agencies by non-Federal entities similar to the process established by the FCC in the adjacent 1850-1990 MHz band. New Congressional legislation would be necessary to effectuate such a process. Title VI required that all microwave communication systems operated by Federal power agencies in this band continue operation and be protected from interference. Federal stations used for limited times during emergency and disaster response will also continue operation and be protected from interference. In addition, certain other Federal operations that provide safety-of-life and other critical functions, and are located outside of the largest 25 cities, will continue operation and will be protected from interference.
In its comments on the NTIA Preliminary Spectrum Reallocation Report (hereinafter NTIA Preliminary Reallocation Report), [EN #18] APCO stated that the 1710-1755 MHz band segment has significant potential for public safety and other private land mobile operations. According to APCO, the band is sufficiently large to accommodate wide-area mobile use of wide-band technology, and is in the same frequency range as the 1850-1990 MHz PCS band.[EN #19]
In their comments to the NTIA Preliminary Reallocation Report, Motorola, TIA, GTE, and APCO agreed that the 1710-1755 MHz band segment can be used for the development of commercial and public-safety applications. Some of the new technologies are wide-band networks to permit high speed transmissions of fingerprints, mugshots, and other images to and from the field. Full and slow motion video is another example of emerging technology. Mobile video, both air and ground, will be used for criminal surveillance, emergency medical response, fire suppression and disaster management. Recently, APCO has filed with the FCC an interest in the 4635-4685 MHz band for mobile video.
2300-2310 MHz. This band is used by the military for radar evaluation, enemy radar simulators, and telemetry systems. The amateur service is also allocated in these bands on a secondary basis. The National Aeronautics and Space Administration (NASA) uses an adjacent band, 2290-2300 MHz, for deep space communications and interplanetary research radar operations. The band has potential for new non-Federal radiolocation, fixed and mobile communication technologies, and is located in close proximity to the 1850-1990 MHz band recently allocated by the FCC for PCS.
The reallocation of the 2300-2310 MHz band is scheduled for August 1995.[EN #20] Reallocation of the 2300-2310 MHz band includes constraints necessary for the protection of NASA's Deep Space Network and Planetary Radar operations at Goldstone, California.[EN #21]
Title VI did not provide statutory authority for reimbursement of Federal agency costs associated with any reallocation of spectrum. However, the displaced Federal functions that result from spectrum reallocation must be preserved in other bands at considerable cost to Federal agencies. Reimbursement of Federal costs, including reimbursement directly from the private sector, will require Congressional legislation. Timely reimbursement is an essential element of the final plan for bands identified for accelerated reallocation. Therefore, the availability of these bands for other uses rests upon timely reimbursement.
APCO notes that some of the frequencies above 1 GHz proposed for reallocation could accommodate new public safety communications technologies, especially the 1.7 GHz band.[EN #22] APCO states, however, that none of the frequencies to be reallocated are below 1 GHz, where all current public safety land mobile systems operate.
4635-4685 MHz. Although the analysis of frequency bands was, in general, limited to those bands below 3 GHz, the 4635-4685 MHz band is worthy of mention because 25 MHz of this band is currently allocated for non-Federal use, and the remaining 25 MHz will be available for non-Federal use in 1997. This band is used for military airborne telemetry and tropospheric scatter communications systems. The band has potential for non-Federal fixed, mobile (except aeronautical), fixed-satellite, and radiolocation services. The 4660-4685 MHz band was transferred to the FCC in 1994. The FCC has proposed a General Wireless Communications Service in the 4660-4685 MHz band. This band could support land mobile PCS-like wireless services. The 4635-4660 MHz band is scheduled for transfer to the FCC in January 1997. However, Federal airborne operations are scheduled to continue in the 4635-4660 MHz band for 14 years at three Federal sites. Wideband services, such as mobile video, would be suitable for this band outside of the three Federal site areas.VHF Television Spectrum
In the NTIA Requirements Study, NTIA noted that terrestrial TV broadcasting in the decades ahead will be dominated by digital technology. Using digital technology would allow the TV broadcast industry to better compete with cable, direct broadcast satellites, multiband multipoint distribution service (wireless cable), video dialtone, VCR's, and all other forms of video distribution. The report examined the broadcasting service spectrum requirements for the future and concluded that no additional spectrum appeared necessary for terrestrial TV broadcasting; however, it noted that the eventual implementation of advanced television (ATV) in the UHF TV spectrum may free some, if not all, of the 72 MHz presently allocated to VHF television. Further, the report noted that this was not expected to occur within the next 10 years and that considerable debate and competition could be expected between broadcasters and other potential users on how this spectrum should be used.
In the FCC's continued effort towards the next era of broadcast television, it is revisiting some earlier decisions in their ATV proceedings.[EN #23] Technological enhancements and additional new information obligated this review since the original ATV focus was on fostering the development of high definition television. The FCC Fourth Notice does not appear to change the NTIA Requirements Study finding that no additional spectrum is necessary for terrestrial TV broadcasting. In fact, more spectrum may be freed up since the FCC is inviting comments on means of achieving greater spectrum efficiency in this proceeding. Our review of this notice still finds that the VHF television spectrum will probably be the spectrum recovered if and when a 6 MHz channel is surrendered and broadcasting in National Television System Committee (NTSC) ceases. For purposes of this report, the VHF television spectrum is still a candidate as a land mobile spectrum planning option.[EN #24] If ATV must also be accommodated in the VHF TV band, locating ATV in the lower VHF bands (54-72 MHz and 76-88 MHz) would allow the upper VHF band (174-216 MHz) to be reallocated for other uses.
TABLE 3-1 VHF TV Channels
Channels Frequency Band (MHz) ___________________________ 2-4 54-72 5-6 76-88 VHF 7-13 174-216 ___________________________
Many in the telecommunications industry are excited about the possibility of having the VHF TV spectrum available for future reuse because, in part, of its ideal location in the electromagnetic frequency spectrum. The land mobile industry as well as the mobile satellite industry have expressed interest in the VHF TV spectrum. TABLE 3-1 depicts the VHF TV channels and their corresponding frequency bands. The VHF TV spectrum is in the band that has long been preferred for mobile/portable and air/ground communications by government, radio amateurs, and commercial organizations. The relatively stable propagation conditions found at these frequencies foster good communications between mobile stations. The VHF band is also ideally suited for line-of-sight communications and allows for the reuse of frequencies. The mobile satellite industry is interested in spectrum between 100-500 MHz for low-Earth orbiting systems.
The land mobile industry's interest in the VHF TV spectrum is also predicated upon the location of various radio services that are adjacent to the VHF TV spectrum. Near TV Channels 2-6, there is 20 MHz of contiguous land mobile spectrum at 30-50 MHz. The primary land mobile uses in this band are for conventional dispatch communications and non-Federal paging. The frequency spectrum for TV Channels 2-6 (54-72 MHz and 76-88 MHz) is near the VHF low band and mobile operations in this band can expect to encounter similar propagation anomalies that VHF low band radio systems experience.
There are approximately 30 MHz of nearly contiguous land mobile spectrum (138-174 MHz) below the frequency spectrum for TV Channels 7-13. Most of this land mobile spectrum is allocated for Federal use and is primarily for dispatch communications, paging, and trunking. The non-Federal usage is primarily for dispatch communications and some paging. Just above Channel 13, the 220-222 MHz band is for Federal and non-Federal land mobile use where there are nationwide/local conventional and trunked radio operations. The frequency spectrum for TV Channels 7-13 is ideal for land mobile use and, together with the surrounding land mobile spectrum, could make for a large and virtually contiguous band for land mobile operations. This spectrum is of particular interest to APCO due to its location adjacent to the 150-170 MHz band, where many VHF channels could become available in metropolitan areas (where the public safety needs are the greatest).[EN #25]
Although the FCC initial plan is for a 15-year period to allow for the transition from analog TV to digital TV, the FCC has indicated its interest in reallocating this spectrum as soon as possible.[EN #26] Some of the spectrum for TV Channels 2-6 could, if needed, be used during the transition period to help implement ATV. But the frequency spectrum for TV Channels 7-13 are more ideally suited for land mobile operations such as paging, conventional dispatch, or trunked radios. Some of the Federal and non-Federal land mobile spectrum requirements, though not specified separately, could be satisfied from this spectrum at some future point.
Since the issuance of the NTIA Requirements Study, the DOT/FHWA has been further defining the ITS architecture, communications options, and spectrum requirements. In order to evaluate the availability of spectrum to satisfy these requirements, NTIA reviewed the usage of the 220-222 MHz band, the 5850-5925 MHz band, and communications needs at frequencies above 40 GHz. The following is a summary of the review.
220-222 MHz Requirements and Availability
The FCC reallocated the 220-222 MHz band to the Private Mobile Radio Services for Part 90 devices in 1988 from the 220-225 MHz band used by the amateur service and Federal Government. The band is divided into 400, 5-kHz-wide channels to create 200 channel pairs. The base stations operate in 220-221 MHz and the mobile units in 221-222 MHz portion of the band. Sixty channel pairs are allocated for nationwide systems, with 20 for commercial carrier fee-for-service repeater operations and 30 pairs designated for private systems. In the channel plan for the 200 pairs, 10 nationwide pairs were allocated for Federal Government use. The remainder of the 140 channels are allocated for local systems.
The DOT/FHWA is using 5 of the Federal Government's 10 pairs for ITS experimentation on new traffic management technologies. DOT/FHWA has recently indicated the need for additional non-commercial frequency pairs in this band, and is planning to petition the FCC to fulfill this requirement since the other five nationwide Federal pairs have been recently authorized for U.S. Postal Service use in its nationwide trucking fleet.
ITS Spectrum Availability Below 10 GHz
The 75 MHz requested by DOT in the 5850-5925 MHz band is presently allocated to the radiolocation services that occupy most of the 4-8 GHz bands. These bands are characterized by pulsed and continuous wave radar systems for a number of vital functions. The largest user is the Department of Defense for its national defense mission. The specific functions are determining precise location, search and surveillance, target tracking, weapons control, ground mapping and target identification, or combinations of some of these functions.[EN #27] These radars can be fixed or transportable, shipborne, and airborne.
The 5250-5925 MHz frequency range is allocated to the radiolocation service on a primary or secondary basis in six bands. There are 1700 frequency assignments listed in the GMF for Federal Government users. Many of these assignments encompass the complete frequency range. The actual number of equipment using these assignments is much larger. The 5850-5925 MHz band requested for ITS is used extensively for test range instrumentation radars to track missiles and other targets. The band is presently allocated to the Federal Government radiolocation service, and fixed-satellite service (Earth-to-space) non-Federal users on a primary basis, and the amateur service on a secondary basis. The International Telecommunications Satellite Organization and other domestic satellite systems use this band for uplinks in the fixed-satellite services.
The FCC, in response to the NTIA Preliminary Reallocation Report, recommended that the 5850-5925 MHz band be paired with the 3625-3700 MHz (space-to-Earth) to provide more usable spectrum for fixed-satellite communications.[EN #28] The FCC also suggested that the 5850-5925 MHz band be exclusively allocated to the non-Federal fixed-satellite service. Subsequent to these FCC actions, legislation was introduced in Congress proposing to transfer the 5850-5925 MHz band to non-government use. This legislation has passed the Senate[EN #29] in July and a companion bill has passed in the House of Representatives in August. Both bills were in conference committee for resolution at the time of this writing.
The 5850-5925 MHz band is allocated to Federal radiolocation service, co-primary with non-Federal fixed-satellite service limited by Footnote US245. Amateur operations are allocated on a secondary basis. Part 15 devices and ISM devices may operate in the 5850-5875 MHz portion of the band, although their current use is believed to be very low. Only one manufacturer's Part 15 system, a radio local area network (LAN), is known to operate in the band, although more of these systems are expected to be accommodated in the future.
A report by the European Radiocommunications Committee of the European Conference of Postal and Telecommunications Administrations (CEPT) recommended that "The 5.8 GHz band (5.795-5.805 GHz with a possible extension to 5.815 GHz, taking account of specific national situation) is designated for ITS applications, expected to be implemented in a very short term in some countries. It mainly concerns communication between vehicle and radios automatic road toll collection." The ITS community in Europe supports this recommendation.[EN #30]
The Federal Government agencies have increasing need for fixed- and mobile-satellite services. Federally-owned earth stations, communicating through non-Federal space stations, do so on an unprotected basis since the allocations are for non-Federal use. NTIA has recently proposed a revision to the National Table of Frequency Allocations that would, among other things, allocate the 5850-5925 MHz band to the fixed-satellite service for both Federal and non-Federal use, where Federal earth stations would be limited to the use of non-Federal space stations. Deletion of Footnote US245 and the reduction of the Federal radiolocation allocation to secondary would allow increased use of the band for the fixed-satellite service. This action is currently before the FCC. Recently Apple Computers, Inc., petitioned the FCC for rulemaking to re-allocate the 5100-5350 MHz and 5725-5875 MHz bands for high capacity, unlicensed wireless data and adopt service rules for a shared unlicensed personal radio network.[EN #31]
The Federal operations in the 5850-5925 MHz band are limited to "range safety" skin-tracking radars and some drone-control functions that are used on remote test ranges and shipborne radar operations. However, it must be noted that this band is at the upper portion of major ground-based radar bands. Some systems in this band use older type magnetron output tubes that have the potential for causing interference to the ITS operations. NTIA has performed resource assessments and spectrum surveys of the 5200-6000 MHz band. A worst-case evaluation indicates a potential problem from adjacent and co-channel radar operations to ITS operations, in addition to harmonics of 2700-2900 MHz operations. Indications are that ITS operations may be possible, but further sharing studies are necessary when exact ITS characteristics are available. These sharing studies should consider all users in the 5850-5925 MHz band and all pending reallocation actions.
ITS Spectrum Availability Above 40 GHz
Because of recent interest in the bands above 40 GHz, the FCC issued a NPRM seeking comments on its proposal to open portions of the bands above 40 GHz for commercial development and use.[EN #32] The current use above 40 GHz consists mainly of satellite uplinks in the 43.5-45.5 GHz band, various environmental monitoring systems scattered throughout the 47-71 GHz band, and high resolution radar systems in the 92-95 GHz band. The FCC currently has no service rules for operations in these bands.
Specifically, four frequency bands were initially proposed in the NPRM for vehicular radar systems. A special IRAC Ad Hoc group reviewed the bands listed in the NPRM, but because of potential compatibility problems and technology considerations, recommended a change in the proposed bands. The Ad Hoc group recommended the 47.2-47.4 GHz, 76-77 GHz, and 152-154 GHz bands. The proposal of multiple bands has the support of the three U.S. automobile manufacturers and the American Automobile Manufacturers Association. They stated that the 76-77 GHz band would satisfy their present radar requirements, and when the technology is fully developed, a need for more precision may require a move to the 152-154 GHz band. Both ITS AMERICA and DOT/FHWA have supported the FCC NPRM on their proposal for consideration of three different bands above 40 GHz for VCAS.
The DOT/FHWA comments endorsing the FCC rulemaking stated that VCAS consisted of the two different services, the collision avoidance radar and the high-capacity, short-range data link. The 10 MHz that was identified as a land mobile communications requirement above 40 GHz is to support this data link; however, the choice of what frequency band would be the best suited for the data link has not been fully defined. There are engineering issues involved in the design of a common system that would support both VCAS requirements. Based on technical and cost considerations, it appears that the choice of the frequency band for the data link should be near the radar bands. Engineering studies indicate that the data link frequency should be between 5 and 10 percent on either side of the radar frequency. Bands were chosen that are allocated for mobile and would be compatible with currently allocated services. Possible spectrum options using the 5-10 percent criteria for the three proposed radar bands are: 49.7-50.2 GHz, 50.4-51.4 GHz, 68.9-72.7 GHz, and 168.0-168.3 GHz.
Summary of Spectrum Planning Options
For the purposes of spectrum planning, the following frequency bands should be considered for satisfying future land mobile spectrum requirements. The 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.
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 Intelligent Transportation System 50.4 - 51.4 GHz 68.9 - 72.7 GHz 168.0-168.3 GHz
As discussed in detail in the Appendix, trunked single-site or multisite systems could be shared among a mix of users, such as Federal and non-Federal, with each type of user having an appropriate set of user groups and priorities. Traditional sharing philosophy is to share a trunked radio system only with users who are very similar in operation, such as the FBI sharing with the Secret Service or perhaps the State Police. This philosophy is prevalent because similar users are likely to share much of the same "agency culture." Unfortunately, similar users are likely to experience emergencies at the same time. If all agencies sharing a system each experience an emergency at the same time, it is likely that there will be a channel shortage at that time.
An alternate option is to share among dissimilar agencies whose major traffic peaks and emergencies are likely to occur at different times. However, it may be difficult to find exact opposite emergency requirements, but the principle works to some degree whenever different agencies (or different functions within a single agency) share a system.
A further alternative would be to mix many low-priority users with high priority users. During emergencies, the low priority users will see their access greatly limited, while their channels become available for high-priority functions.
The concept of sharing should continue to be explored and is encouraged by NTIA to promote more efficient spectrum use and system interoperability where feasible. Sharing can also satisfy some of the additional spectrum shortfalls that were identified in the NTIA Requirements Study.
1. Association of Public-Safety Communications Officials-International, Inc. (APCO), Public Safety Spectrum Needs Analysis and Recommendations, August 1994 [hereinafter APCO Report].
2. National Telecommunications and Information Administration, U.S. Department of Commerce, NTIA Special Publication 94-31, U.S. National Spectrum Requirements: Projections and Trends (1995) [hereinafter NTIA Requirements Study].
3. Federal Communications Commission, Office of Engineering and Technology, OET/TS 91-1, Creating New Technology Bands for Emerging Telecommunications Technology, December 1991, at 5 [hereinafter OET 2 GHz Study].
4. M. Paetsch, In the U.S. and Europe: Regulation, Technology and Markets, Mobile Communications, at 64 (Artech House).
5. FCC Report 95-55, Report and Plan of the Federal Communications Commission, Meeting State and Local Government Public Safety Agency Spectrum Needs Through the Year 2010, Federal Communications Commission, February 9, 1995, at 36.
6. This discussion considers spectrum efficiency from an engineering standpoint. NTIA has already studied at various times ways to increase "economic efficiency" through flexible use of spectrum and greater reliance on market-based mechanisms, including auctions. Such issues are outside the scope of this report. See NTIA Spectrum Policy Study, Chapters 3 and 4 for further discussion of flexibility and market-based approaches to spectrum management.
7. See NTIA Spectrum Policy Study, Chapter 5, for further discussion on spectrum efficiency.
8. The term "wireline" is applied to systems that use electromagnetic transmissions, but are inter-connected by wire, fiber optic cable, or other non-radiating media.
9. National Telecommunications and Information Administration, U.S. Department of Commerce, NTIA Special Publication 95-32, Spectrum Reallocation Final Report (1995) [hereinafter NTIA Final Reallocation Report].
10. Allocations of Spectrum Below 5 GHz Transferred from the Federal Government Use, FCC Notice of Inquiry, ET Docket 94-32, FCC 94-97, 59 Fed Reg 6005 (May 4, 1994) [hereinafter FCC NOI].
11. NTIA Final Reallocation Report, supra note 6 at Table 4-1.
12. FCC NOI, supra note 7.
13. National Association of Business and Educational Radio Inc. (NABER) Comment at 17 (June 15, 1994), filed in response to FCC NOI, supra note 7.
14. NTIA Final Reallocation Report, supra note 6 at Table 4-2.
15. Meeting between NTIA and Motorola on July 13, 1994.
17. NTIA Final Reallocation Report, supra note 6 at Table 4-3.
18. National Telecommunications and Information Administration, U.S. Department of Commerce, Special Publication 94-27, Preliminary Spectrum Reallocation Report (Feb 1994) [hereinafter NTIA Preliminary Reallocation Report].
19. APCO Comments at 6 (May 11, 1994) (filed in response to the NTIA Preliminary Reallocation Report, supra note 15).
20. This was done to provide the opportunity for effective pairing with the 2390-2400 MHz band. However, the FCC has reallocated the 2390-2400 MHz band for unlicensed PCS devices.
21. NTIA Final Reallocation Report, supra note 6.
22. APCO Report, supra note 1 at 20.
23. Broadcast Services: Advanced Television Systems, Fourth Further Notice of Proposed Rule Making and Third Notice Of Inquiry (MM Docket No. 87-268; FCC 95-315), 60 Fed. Reg. 42130 (1995) [hereinafter FCC Fourth Notice].
24. In its efforts to implement advanced television services (ATV), the FCC made a tentative decision in 1992 to establish a transition program where the TV broadcasters maintain service to existing National Television Systems Committee (NTSC) receivers until ATV becomes the prevalent television medium (NTSC TV is broadcast in analog). The planned ATV services will be digital). In the transition program, broadcasters would temporarily be provided with a second channel to allow them to simulcast NTSC and ATV services. Thereafter, the stations would relinquish their NTSC channel after 15 years when it is assumed that most of the consumers would have replaced their TV sets with ATV-capable sets. The development of the U.S. HDTV standard has been years in the making. Finally, this spring the Advanced Television Test Center tested the HDTV system prototype hardware and is to submit a proposed standard in late 1995 to the FCC for final certification. In the meantime, the FCC has reopened the ATV proceedings (see Endnote 23) to review and possibly modify many of its preliminary ATV decisions.
25. APCO Report, supra note 1 at 19.
26. Communications Daily, April 5, 1995. Vol 15, No. 65, "Hundt Says PCS Auctions will be Model for Future Allocations" at p.2-3.
27. Radars performing several of these functions are called multi-function or multimode radars. Although multi-function radars have existed for many years, recent technological advances have spurred new research in this area. Multi-function radars offer spectrum conservation as one radar can perform the function of several radars operating in different frequency bands. Thus, it is an important research subject with the potential of conserving the spectrum.
28. Report from the Federal Communications Commission, to Ronald H. Brown, Secretary, U.S. Department of Commerce, Regarding the NTIA Preliminary Reallocation Report, FCC 94-213, (Aug 9. 1994).
29. S. 652, 104th Cong., 1st Sess. (1995).
30. Presented to the European Radiocommunications Committee and CEPT Administrations March 1993, ISBN 92-9135-001-3.
31. IRAC Document No. 29340/1, Apple Computer Petition For Rulemaking (RM 8653), "NII Band", May 24, 1995
32. 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).