The mobile service is a "radiocommunication service between mobile and land stations, or between mobile stations."[EN13] This includes the conventional land, maritime, and aeronautical mobile services, common carriers such as cellular telephone and radio paging, and new applications like PCS and elements of the Intelligent Transportation System (ITS, formerly the Intelligent Vehicle Highway System, or IVHS).
Mobile radiocommunication applications have been in use since the early part of this century, starting with ship–shore radiocommunications, although recent years have seen tremendous growth. This expansion has been stimulated both by technological advances and by increased demand for mobile services. Advancements in semiconductor technology allow for low–cost, lightweight, portable units and are, in part, responsible for the increase for land mobile services.
Mobile services are used by Federal, state and local government entities for many purposes, including such critical functions as law enforcement, public safety, natural resource conservation, transportation, and national defense. The private sector uses mobile services to satisfy the myriad of conventional communications requirements, including specialized needs such as electronic news gathering,[EN14] aeronautical public correspondence, and biomedical telemetry.
In the 1980's, mobile-satellite service technology advanced from initial concepts to practical system design and service demonstrations. Today, the competition to build global satellite networks is intense. Companies around the world have proposed to use satellites to deliver mobile services, which are expected to generate large revenues. For communication service providers and users, satellite-based systems offer ubiquitous coverage of large geographical areas, the remotest of which may be uneconomical for coverage by terrestrial-based systems.
The land mobile service is a mobile service between fixed base stations (often with the use of repeaters) and stations capable of surface movement within the geographical limits of a country or continent (i.e., land mobile stations), or between land mobile stations.[EN15] These uses include mobile radiotelephony (such as cellular radiotelephone), radio paging, and dispatch-type communications. Additionally, new applications such as PCS and elements of ITS may also be licensed as land mobile services. Land mobile services are used by commercial firms, the public, and by Federal, state and local governments agencies.
One of the fastest growing segments of the mobile telecommunications industry is terrestrially-based radio services to mobile users in cars, in trucks and on foot.[EN16] Further, land mobile services and emerging technologies, such as PCS, are widely discussed and anticipated in the United States. For these reasons, NTIA undertook a study addressing current uses, technology trends, and spectrum requirements within the land mobile service.[EN17] Much of the information contained in the ensuing paragraphs is extracted from that study.
The general public has access to land mobile services by way of fully regulated service providers called common carriers. Common carriers are regulated by the FCC under Part 22 of the FCC Rules, and are subject to tariffs and regulations written by state public utility commissions. However, some common carrier services, such as cellular radio are now part of the Commercial Mobile Radio Service.[EN18] Recent legislation has amended the Communications Act of 1934 so that substantially similar services be treated with "regulatory parity". Other common carriers in the land mobile service include the conventional land mobile telephone system, and radio paging.
Land Mobile Telephone
In the mid 1960's, a mobile telephone system using analog FM, with such features as automatic frequency selection, direct dialing, and full duplex was introduced as the Improved Mobile Telephone System (IMTS). IMTS was designed to emulate the features found in the landline telephone networks. The service was field tested in Harrisburg, Pennsylvania, from 1962-1964, with commercial service offered beginning in 1965.
Conventional land mobile telephone systems have seen limited use since the inception of cellular systems. Many of the original IMTS frequencies are used in rural areas to interconnect to the local telephone service, where cellular service is not yet available.
The concept of cellular radiocommunications was developed by AT&T Bell Laboratories in 1947. It took, however, more than three and a half decades before the first cellular network began operating in October, 1983. As of March 1994, "1,529 cellular systems, employing nearly 40,000 people, [had] been activated in 734 markets across the United States."[EN19]
A cellular system is a mobile, two-way radio telephone system operating in the 824-849 MHz and 869-894 MHz bands that uses controlled, low-powered transmitters and divides the service area into small "cells". The radius of a cell, which ranges from 2 km to 32 km, is partly determined by the transmitter power of the base station, but also by careful use of terrain shielding, reduced antenna height, and directional antennas. Consequently, for a given number of frequencies per cell, the use of smaller cells allows a given frequency to be re-used in other nearby geographic areas, allowing more users to be served by a given set of frequencies.
Cellular telephony has experienced phenomenal growth since its inception in 1983. Public acceptance of cellular has grown at a rate faster than TV, cable TV, VCR's, and facsimile. Even during the recession in 1991, the number of subscribers grew at an annual rate of approximately 43 percent. This growth rate represented an additional 2.3 million new subscribers within a 12-month period. The Cellular Telecommunications Industry Association (CTIA) estimates that 17,000 subscribers are added each day. Cellular growth rate is attributed in part to the unique and appealing operational characteristics of the cellular system—mobility and instant communications. Other factors include the reduced size and decreasing prices of the mobile and portable equipment.
Radio paging, in existence since the 1950's, is one of the older forms of land-based mobile communications services. It is a one-way calling system operating within the 30 MHz, 150 MHz, 450 MHz and 930 MHz bands, which allows for ubiquitous communications access. It has evolved from the transmission of a simple tone signal or "beep" to its present orientation toward limited transmissions of alphanumeric messages. It is in this context of evolution that the radio paging industry provides various types of services and, consequently, has survived against challenges by newer types of mobile communications.
The rapid growth of the paging services is matched by the growth in retail pager distribution and new service offerings. Despite the recession in 1991, the paging industry sustained a record growth of an additional 1.9 million pagers in service compared to 1.8 million additional pagers in 1990. The U.S. paging industry reached a total of 19 million pagers in service with an estimated service revenue for 1993 of $3 billion. The paging industry experienced a 20 percent annual growth rate from 1990-1992.[EN20]
The private land mobile radio (PLMR) services allow state and local governments, and commercial and non-profit organizations to use the electromagnetic spectrum for mobile and ancillary fixed radiocommunications[EN21] to assure the safety of life and property, and to improve productivity and efficiency. These communications are not intended for general public use. However, recent legislation has amended Section 332 of the Communications Act so that many private land mobile services would be classified as simply "commercial mobile services."[EN22] The rules and regulations governing private radio are contained in Part 90 of the FCC Rules. The FCC has allocated portions of spectrum for the various PLMR services in the following bands: 25-50 MHz, 150-174 MHz, 220-222 MHz, 450-512 MHz, 806-824 MHz and 851-869 MHz (the "800 MHz" band), and 896-901 MHz and 935-940 MHz (the "900 MHz" band). Twenty PLMR services are grouped into broad categories such as public safety, industrial, and land transportation radio services. The different services are assigned different frequencies in accordance with Part 90. Channels are available for either conventional or trunked dispatch operations.
Additionally, Part 90 authorizes one-way paging operations, called private carrier paging (PCP), the Location and Monitoring Service (LMS),[EN23] biomedical telemetry and operations within the specialized mobile radio (SMR) service.
The FCC has allocated spectrum within the 150 MHz, 460 MHz and 929 MHz bands for PCP's. Recently, the FCC agreed to open up PCP eligibility to non-Part 90 users, thus permitting services to individuals.
An SMR system is a radio system in which licensees provide land mobile communications services (other than radiolocation) on a commercial basis to eligible Part 90 entities.[EN24] It is a successful, multimillion dollar industry that has been in existence for two decades. SMR operators provide spectrally efficient, trunked private dispatch communications within the 800 MHz and 900 MHz bands.[EN25] Over 80 percent of the customers who subscribe to SMR services are in the construction, service, and transportation industries. There are over 1.5 million SMR units in operation, with industry sales in 1993 totaling $104 million. Enhanced SMR's (ESMR's) are the next generation of digital systems that provide a greater increase in capacity over the analog systems. These wide-area systems would be treated as commercial mobile systems, and hence, subject to the same "regulatory parity" as cellular systems. Portable biomedical telemetry systems are used primarily to monitor the electrocardiogram of patients recovering from heart attacks. The systems allow ambulatory cardiac patients to move about within a hospital, while nurses monitor their heart functions from a central facility. The data is transmitted by a lightweight monitor, via radio, to a sensitive receiving system with antennas generally installed in the ceilings of the hospital corridors. Medical necessity requires that telemetry transmissions be continuous, real-time, and without any interruption or radio interference. Radio frequency spectrum currently available to support these biomedical telemetry applications includes the 174-216 MHz band on an unprotected, nonlicensed basis under FCC Part 15 Rules, and the 450-470 MHz band on a secondary basis, under FCC Part 90 Rules.
There are over 16 million PLMR transmitters, 12 million of which operate below 800 MHz. Between 1984 and 1991, the number of licensed transmitters grew at an annual rate of 10 percent per year.[EN26]
The land mobile service is vital to the Federal Government in supporting the public service missions of the Federal agencies. Federal operations supported by the mobile services often represent nationwide or worldwide applications, as well as local service areas that can range in location from remote to urban areas.
The Federal Government's requirements differ significantly from that of most of the non-Federal users because of the safety-of-life implications of many Federal services, the Federal need for nationwide coverage, missions that are mandated by Congress and the President, and operations that are not revenue-driven. Among these unique requirements or missions are: protection of the President and other high-level officials, both U.S. and foreign, providing for the national security; promoting public safety and efficiency in traveling via air, water and land; interdicting entry of illegal personnel and substances into the United States; establishing communications between disaster areas and relief forces; ensuring the swift search and rescue of human life; protecting the national forests, parks, and farmlands; bringing to justice perpetrators of Federal crimes; and ensuring the security of energy generation and distribution networks. In addition, Federal emergency response and public safety organizations conduct large scale exercises to prepare for and respond to a wide variety of emergencies and disasters, such as hurricanes, earthquakes, and chemical and nuclear power plant accidents.
The Federal Government non-tactical land mobile operations are accommodated in portions of the 30-50 MHz, 138-150.8 MHz,[EN27] 162-174 MHz, 220-222 MHz, and 406.1-420 MHz bands. These bands, specifically the 162-174 MHz and 406.1-420 MHz, are the most widely used by the Federal agencies. Currently, there are 48 Federal agencies authorized to operate in the 162-174 MHz band and 47 agencies in the 406.1-420 MHz band. The land mobile service is the dominant service used by the Federal agencies in these bands. Federal trunked mobile radiocommunications systems are accommodated primarily in the 406.1-420 MHz band.
A typical Federal non-tactical land mobile radio system uses a wide range of equipment in a variety of geographic environments supporting voice and data communications for non-tactical operations. The range of equipment includes base, repeater, vehicular, and hand-held stations. Federal land mobile radio systems are usually multi-purpose systems; for example, law enforcement, natural resource, medical, administrative, and utility functions may be supported by the same radio system or network. The radio systems, which are purchased from commercial vendors, are similar to those employed by non-Federal entities.
Federal land mobile service operations, other than radio paging, are usually two-way communi- cations between a base and mobile station or between mobile stations. Federal users communicate in a dispatch/supervisory mode (one-to-many) or communicate in a one-to-one mode while other users monitor the channel and take action as appropriate. Typical messages from mobile sources are of relatively short duration. Typical channel hold times for Federal Government mobile communications are quite short, usually less than a minute. Under these circumstances, one or more channels can often be shared by several independent users. Although Federal agencies use common carrier services such as cellular telephones[EN28] and radio pagers to augment communication needs, they do not serve as replacements for the agency's own land mobile systems.
The number of assignments in Federal land mobile bands has been steadily increasing over the last 20 years, particularly in the 138-150.8 MHz, 162-174 MHz, and 406.1-420 MHz bands, reflecting the increase of missions in support of the public. The number of assignments in the 30-50 MHz band has been increasing at an average rate of approximately 3 percent per year,[EN29] while the 138-150.8 MHz band growth rate is nearly 7 percent per year. The assignment growth rate in the 406.1-420 MHz band has been 12 percent per year over the last three years, while the 162-174 MHz band experienced an 8 percent per year increase over the same period.
Currently, significant effort is being focused on the land mobile services in order to increase their spectral efficiency and capacity, and to satisfy increasing user demand. The Federal and non-Federal sectors are undertaking parallel efforts to increase spectrum efficiency in the land mobile bands that are under their respective control. Two of the more important technology trends in the land mobile service are the migration to narrowbanding and to digital, multiple-access techniques.
The FCC, recognizing the growing spectrum requirements of the PLMR services, has plans to "refarm" the PLMR bands below 512 MHz. On July 2, 1991, the FCC released a Notice of Inquiry (NOI)[EN30] to gather information on how to promote more efficient use of the frequency bands below 512 MHz allocated to the PLMR services. The NOI solicited comments on a wide range of technical and policy issues, with the overall goal of developing new rules to support future technologies relating to PLMR bands below 512 MHz. Over 120 comments and reply comments were received by the FCC, mainly from the private sector. Many of the commenters emphasized the urgency to increase spectrum efficiency through technical and policy changes.
Based on the received responses to the NOI, the FCC adopted on October 8, 1992, a Notice of Proposed Rulemaking (NPRM)[EN31] that contained a comprehensive set of proposals designed to increase channel capacity through narrowbanding,[EN32] promote efficient use of PLMR bands, and simplify current policies governing the use of PLMR bands below 512 MHz. In addition, the FCC proposed to abolish Part 90 and create Part 88 of the FCC Rules.
In the fall of 1992, Congress requested that NTIA develop and implement a plan for Federal agencies to use wireless technologies that are at least as spectrum efficient and cost effective as readily available commercial mobile radio systems.[EN33] In response, NTIA began its efforts by analyzing the current Federal land mobile infrastructure with respect to spectrum efficiency and cost effectiveness.[EN34] NTIA has selected a 12.5 kHz channel width for rechanneling, which will double the number of basic channels available. Federal agencies have already begun procurement of these new radios for the 162-174 MHz and 406.1-420 MHz bands. The 138-150.8 MHz band is also to be rechannelized.
The resulting plan will ensure that Federal agencies use commercial or shared land mobile services where practical, use the most spectrally-efficient technologies available by halving the permissible channel widths;[EN35] and use the spectrum allocated to land mobile services more efficiently by restructuring provisions for its use.
Jointly sponsored by the Association of Public-Safety Communications Officials International, Inc. (APCO),[EN36] the National Association of State Telecommunications Directors (NASTD), [EN37] the Telecommunications Industry Association (TIA)[EN38] and agencies of the Federal Government (NTIA, National Communications System, National Security Agency), APCO Project 25 was formed to develop interoperability standards for the next generation public-safety mobile radio, including standards for trunked systems, mobile data systems, console interface, and encryption. The goals of Project 25 are "to develop standards for equipment which would ensure a graceful migration between techniques and intercommunications between the products of different manufacturers."[EN39] These systems will use 12.5 kHz channels, with a full range of digital data and vocoder features, including encryption. It is anticipated that the work being accomplished in Project 25 will have a profound effect on Federal and non-Federal public safety services.
Although cellular radiotelephony represents a revolutionary advance in mobile communications technology, most systems transmit voice signals using standard analog FM within a 30 kHz channel bandwidth. Because of the limited capacity per channel offered by this technology, there is a need to venture into other technologies that can provide the solution to the current, limited capacity in the cellular industry. Most manufacturers in the cellular industry agree that digital technology offers greater capacity per channel and more features, such as improved voice transmission quality, improved security, and greater system accessibility than analog FM technology.[EN40] However, a dilemma within the cellular community has arisen as to what digital technology will be implemented for the U.S. cellular industry.[EN41]
In 1992, the cellular common carrier section of the TIA TR-45 committee developed a U.S. cellular industry standard, called the "IS 54", based on a digital, TDMA technology. Pioneers of TDMA have claimed a threefold increase in capacity per channel over conventional analog cellular systems for the first generation of the TDMA systems. The next generation of TDMA systems will further increase the capacity of a channel to six times over the standard analog systems. In February 1992, the CTIA endorsed TDMA as a standard.
Other digital systems employing different techniques such as code-division multiple-access (CDMA) or spread spectrum are being implemented. In early 1992, PacTel Cellular was the first cellular entity to commit to the CDMA format. During that time, the TIA's TR-45 committee voted to begin a standards-making process for spread spectrum, represented by CDMA technology. Preliminary analysis of CDMA systems project several advantages over TDMA, including the ability to share frequencies with other radio services and substantially greater capacity (e.g., 20 times as much as existing conventional analog systems). After three years of development, testing and demonstrations, TIA Subcommittee 45 adopted CDMA digital technology as an industry standard called IS-95. The progression toward a digital system is inevitable and will definitely bring about increased use of mobile, non-voice services such as facsimile, E-mail and others, over the cellular network system. A trunked system supports a number of users on a group of channels, providing the spectrum efficiency benefits of channel sharing while minimizing blocking. When a user wishes to make a call, the system selects an available channel from the group and automatically tunes the user's transmitter to that channel while directing the appropriate receivers to switch to that channel also. Trunking improves spectrum efficiency by providing more user access for a given number of channels. Next-generation trunking systems will be even more efficient than current trunking systems. Nextel, formerly Fleet Call, has recently activated the first digital trunked mobile network in Los Angeles, Riverside, and parts of Orange and Ventura Counties in California.[EN42] This ESMR system incorporates innovative state-of-the-art technology, including digital speech coding and TDMA transmission, to create six voice channels using a single 25 kHz channel. ESMR's use low-power base stations, permitting geographic frequency reuse. Nextel estimates that these technologies can provide over 15 times the customer capacity as existing SMR systems.[EN43]
Intelligent Transportation System
In the United States, there is growing interest in the development of an automated highway system that will provide for safer and better informed travelers, improved traffic control systems, systems aimed at increasing the efficiency of commercial vehicle and transit operations, and increase national productivity. Advanced technologies will be an integral element of a future transportation infrastructure. Probable configurations will both include mobile data links between vehicles and links between vehicles and the roadside infrastructure for automatic toll collection, route guidance, collision avoidance, etc. ITS is the general term applied to this broad application of modern communications, location, and control technologies to the needs of vehicle transportation. The next five years will see the research and development, evaluation, and operational testing of the following ITS projects and applications:
Traveler Information Systems Traffic Control Systems Route Guidance and Navigation Systems Rural Applications Transit Fleet Management Systems Commercial Vehicle Applications Fare Collection and Smart Cards Commercial Vehicle Network Systems Collision Avoidance Systems Automated Highway Systems[EN44] Transportation Demand Management Systems
The Federal Government involvement in the ITS stems from the Intermodal Surface Transportation Efficiency Act of 1991, which designates the Department of Transportation (DOT) as the lead agency.[EN45] The DOT recently completed a national strategic plan and has initiated efforts to develop a national ITS architecture by 1996.[EN46] In the coming years, the DOT will be working as partners with the Intelligent Transportation Society of America (ITS AMERICA, formerly IVHS AMERICA) and its members to help guide and advance the national ITS program.[EN47]
The DOT, recognizing that the many radiocommunication elements of ITS would be frequency-dependent, developed a radio frequency acquisition strategy for ITS. Its two aims are: first, to obtain specific dedicated frequencies suitable for supporting certain baseline ITS functions on a nationwide basis; and second, to maintain currently available spectrum and identify new opportunities for sharing communications capacity with emerging telecommunications technologies.[EN48]
The ITS will be supported by more than one radio service. Some ITS projects and programs are currently being defined, while other projects are in the testing and evaluation or operational stages. The radio service associated with these projects and programs depends on the use, and could be a combination of the mobile, radiolocation, radionavigation, radionavigation-satellite, fixed, and possibly broadcasting services in the near future. ITS could also employ Part 15 devices and PCS systems. Since most of the ITS systems and user functions are related to the mobile radio service, ITS is included in this chapter.
Current ITS-related systems operate from 100 MHz to 1 GHz. Most of the commenters to our Inquiry focused in this frequency range. Present FCC policy allows the use of the 902-928 MHz band for LMS functions.[EN49] One LMS system currently uses 904-912 MHz and employs pulse-ranging multilateration techniques.[EN50] In this system, a vehicle location unit installed in a vehicle communicates with a computer at a network control center through a network of transmission and receiving towers. Within a defined geographic area, a host of practical applications can be provided: monitoring the location of fleet vehicles, accurate tracking of stolen vehicles, and helping motorists in distress.
Narrowband LMS systems also operate in the 904-912 MHz and 918-926 MHz bands. In one of these types of systems, a tag is affixed or placed in the vehicle to be located. The vehicle is interrogated by the LMS station as it passes nearby. The interrogating signal is either modulated with unit-specific information and reflected back to the station's receiver, or the tag transmits its own signal in response to the interrogation.[EN51] As with the system described above, status information or instructions can be transmitted to and from the unit being monitored or located.
One city has equipped a large number of its public buses with LORAN-C receivers and 800 MHz mobile radios for fleet monitoring to help provide greater on-time services. Bus locations are determined by the LORAN-C receivers and transmitted via the radio to a central dispatch center. Bus status information is provided to the public while simultaneously improving bus schedule adherence and labor productivity.[EN52] A major commercial bus company is presently using a vehicle on-board radar (VORAD) collision warning radar system on its 2,400 buses, which notifies drivers when vehicles or objects are in critical areas in front of or in the blind spots of the buses.[EN53] The forward-looking radar operates at 24.125 GHz; the blind spot radar at 10.525 GHz. In-vehicle navigational systems that provide information to the driver using both video displays and voice outputs to provide electronic maps, route guidance, and vehicle location are under operational testing. These include: ADVANCE (Chicago), FAST-TRAC (Detroit), and Pathfinder (California).[EN54] Further, U.S. car manufacturers will be offering a route guidance and navigation system as an option on some 1995 cars.
Today, ITS services such as the automatic vehicle monitoring, stolen vehicle recovery, and electronic toll and traffic management services are becoming readily available in the United States. Additionally, ITS products are increasingly available, including vehicular collision avoidance radar, in-vehicle computer-based navigation systems, and electronic road signs. The FCC is considering the creation of the Transportation Infrastructure Radio Service (TIRS) to regulate, as it pertains to ITS, new services and or spectrum as they are added to improve the nation's transportation system.
Personal Communications Services
The increase in demand for mobile telecommunications has given rise to a wide array of new technologies and systems. This wide array of future alternative services spans a very large range of frequency allocations, expected data bandwidths, and assumptions regarding user mobility, location, and personal choice of potential service offerings.
Countries and businesses around the world have proposed new mobile applications that will deliver a wide variety of new (and old) services, including paging and messaging, telephone, facsimile, data communications, and even imaging and video. In the United States, these systems are often included in PCS. Many consider the international counterpart of PCS to be the Future Public Land Mobile Telecommunications Systems (FPLMTS).[EN55]
The term "PCS", as defined by the FCC, is a family of mobile or portable radiocommunications services which could provide services to individuals and businesses, and be integrated with a variety of competing networks. Emerging PCS will include some services that are not currently being offered to the public, and are conceptualized to provide a new combination of capabilities.
The FCC has recently allocated a total of 140 MHz of spectrum for 2 GHz PCS. The FCC adopted a modified plan that provides for three 30 MHz licenses (Blocks A, B, and C) and three 10 MHz licenses (Blocks D, E, and F), all of which are within the 1850-1990 MHz band. The FCC also maintained an allocation of spectrum at 1910-1930 MHz for unlicensed PCS devices and committed to examine in the near future allocation of additional spectrum for unlicensed PCS operations. Also, 80 MHz of spectrum will be placed in reserve. Figure 1-1 summarizes what the FCC has authorized for new PCS services in the 2 GHz band and, for comparison purposes, what WARC-92 has identified for FPLMTS and has allocated for mobile-satellite service uplinks and downlinks in these bands.Figure 1-1. Emerging wireless technologies allocations.
The PCS being developed today will have significant improvements over those services currently available. Among these emerging PCS are telepoint and advanced telepoint, personal telecommunications (e.g., Personal Communications Network or PCN and Enhanced Private Communications or EPC), advanced cordless, and wireless private branch exchange (PBX). The most significant trend of these emerging services appears to be toward person-to-person communications, vice telephone-to-telephone (i.e., universal personal communications). Future PCS would permit individuals to use the same identification number in several different environments. Some of the emerging PCS are briefly described below.
Telepoint is a service that offers the ability to place calls from a pocket-sized telephone whenever the user is within range of a serving base station. It provides call origination only from a personal device into the PSTN. The coverage provided by a telepoint system is limited to discrete locations; hand-off between base stations is not provided. It provides medium-to high-quality voice and low-speed data communications. The handsets are relatively small, lightweight and low-cost.[EN56]
Advanced telepoint is a service that allows a user to both place and receive calls from their personal device. Hand-off between base stations is possible, giving a limited amount of mobility during the call is envisioned. Like telepoint, advanced telepoint would provide high-quality voice and low-speed data communications but, probably faster than telepoint. When offered to closed user-groups, like residences or private businesses for example, such service would be described as Advanced Cordless/Wireless Private Branch Exchange (AC/WPBX). Hand-off between a private and public network would be possible, but not required.
Personal Telecommunications Services
Personal Telecommunication Services (PTS) is a service that will bear a functional resemblance to cellular service from an end-user perspective. The main difference is that the size of a PTS cell will be much smaller than that of the cellular systems, thus permitting lower power transmitters than cellular and smaller, lighter handsets than cellular. PTS would provide high-quality voice and medium-speed data communications. It would also provide call origination and termination from a personal device to other devices or locations. The coverage provided by a PTS network will be ubiquitous within a defined service area, for example, local, wide-area or regional. Hand-off between base stations would be provided and hand-off between a private and public network would be possible, but not required.
Advanced Cordless/Wireless Private Branch Exchange (AC/WPBX)
AC/WPBX is a service that will be offered to closed user-groups or used as part of an internal communications system. AC/WPBX would provide high-quality voice and medium-speed data communications. It would provide call origination and termination from a personal or shared device to the PSTN. Coverage would be limited to defined service areas, typically within buildings or neighborhoods. In addition, the coverage might be extended or integrated with a public network such as Advanced Telepoint, ESMR, Enhanced Cellular, or PTS. Hand-off between base stations would be provided and hand-off between a private and public network would be possible, but not required. Handsets are expected to be similar in size and weight to other PCS units.
Data devices would provide non-voice communications between terminals. For example, these devices would send data messages in the form of electronic mail or facsimile through wireless local area networks (LAN's) and pagers. Some companies have already developed booksize PCS devices that reportedly combine a cellular phone, note pad, fax machine and personal computer. Generic names for such devices include Personal Digital Assistant and Information Appliance.
An unresolved issue is whether or not consumers who already have access to cellular phones, pagers, voice mail, and other wireless communications will pay for yet another technological alternative. Some analysts predict that PCS will generate revenues between $35 to $40 billion beyond current wireless revenue levels.[EN57]
A PCS market forecast for the years 1998 and 2003 is shown in Figure 1-2. Values in the figure for the emerging 2 GHz PCS were derived from a survey conducted by the Personal Communications Industry Association (PCIA)[EN58] in January, 1994. PCIA estimates that there will be 8.55 million subscriptions[EN59] for new 2 GHz PCS services in 1998. This estimate is based on a penetration of the population of 3.1 percent. In 2003, PCIA estimates that the number of subscriptions to new 2 GHz PCS will be 31.11 million, based on a penetration of the population of 10.4 percent. This represents a 264 percent increase from 1998 estimates. Assuming linear growth extrapolation, the number of subscriptions in 2004 could be approximately 35 million.Figure 1-2. PCS market forecast.
Federal user requirements for emerging wireless services encompass a broad array of user needs in the civil and defense agencies. Emerging wireless services will enhance the performance and efficiency of the day-to-day operations of law enforcement, drug enforcement, health and human services, defense, and countless other activities. These services will also play a significant role in disaster relief and crisis situations. These requirements have been generally characterized as Digital, Ubiquitous, Interoperable, Transparent, and Secure (DUITS).
Federal use of emerging wireless services such as PCS services will supplement the Federal mobile service infrastructure. The Federal Wireless Users' Forum (FWUF) is reviewing Federal requirements for PCS and has suggested that Federal PCS requirements may be accommodated by one or more of the following spectrum approaches:[EN60]
The Department of Veterans Affairs (VA) stated in its comments that PCS will have a major impact on two-way communications, possibly reducing or eliminating their requirements for conventional two-way radio, cellular, and radio paging systems.[EN61] Other Federal agencies have indicated that PCS may provide only limited spectrum relief or have little impact on land mobile users.[EN62]
The Department of Energy (DOE) has formulated a strategic planning program for its Information Resource Management into the 21st Century called IRM Vision 21. Since radiocommunication services are a critical element of the program, DOE used IRM Vision 21 as a basis for its response to the Inquiry. If DOE projections for the rapid development and deployment of PCS are accurate, PCS will soon be an important element of the mobile radio infrastructure. In particular, DOE offers these predictions for the future of PCS services:
Emerging telecommunications technologies such as PCS promise effectiveness and efficiency throughout the Federal Government and the United States. PCS will also significantly change the telecommunications infrastructure within the Federal Government. DOE radiocommunication strategies [include the use of] terrestrial and satellite PCS network systems, when and where feasible and practical, to augment and/or replace existing land mobile communication systems . . . . Terrestrial and satellite PCS networks and systems will be available in the mid to late 1990's. The Federal Government should consider the feasibility of obtaining a PCS version of the Federal Telecommunications System 2000 network . . . . [DOE] intends to evaluate PCS when available and envisions the potential use of wireless and PCS in the next 5 to 10 years, which will significantly change the telecommunications infrastructure throughout DOE.[EN63]
Several commenters indicated that technology will provide only limited relief. TIA indicated that although there has been significant progress in technological advancement, the demand for land mobile spectrum may be pushed to the limits of practicality.[EN65] The Land Mobile Communication Council (LMCC) stated that growth in urban areas must be satisfied with techniques other than just technological advances, for example, more spectrum.[EN66] In contrast, however, Fleet Call believes that technology still has the ability to relieve spectrum congestion.[EN67] Most of the commenters to the Inquiry indicated that land mobile services need additional spectrum.
Public Safety Requirements
There is growing concern not only by public safety users and manufacturers, but Congress as well, over the lack of spectrum dedicated for public safety use. A variety of factors, including increasing population density and higher crime rates, are placing ever-increasing demands on public safety agencies and, therefore, their communication systems.[EN68] APCO contends that in the interest of public safety, additional spectrum is needed. APCO contends that while new technology will alleviate some requirements, it cannot keep pace with ever-increasing demands. APCO urges NTIA to work with the FCC to find ways to allocate additional spectrum for vital public safety communications.[EN69]
In 1985, the FCC released an extensive study projecting public safety needs through the year 2000.[EN70] This study estimated that to meet the anticipated demand, additional public safety frequency allocations of between 12.5 MHz and 44.6 MHz would be needed in the 21 largest metropolitan areas by the year 2000, even assuming the use of advanced spectrum efficient technologies.[EN71] APCO noted that "so far, the FCC has allocated just 6 MHz nationwide in the 800 MHz band for public safety (and an additional 6 MHz in the UHF TV band for the especially congested Los Angeles area)."[EN72] APCO notes that future technologies now being developed suggest even greater spectrum needs. These include, for example, the ability to transmit maps, criminal records, mug shots, fingerprints, and even the use of video.[EN73]
The Omnibus Budget Reconciliation Act of 1993 requires that the FCC, by February 1995, complete a study of the current and future spectrum needs of public safety agencies through the year 2010 and develop a specific plan to satisfy those needs.[EN74] Because of similar wireless communications needs of both Federal public safety agencies and state and local public safety agencies, the FCC has asked NTIA for assistance regarding this study.[EN75] Additionally, NTIA, as part of the Land Mobile Efficiency Plan,[EN76] will investigate the common public safety spectrum needs of Federal, state, and local agencies and explore the potential for increased sharing of systems and spectrum resources.
APCO has provided input to the FCC regarding that study and has made the following suggestions for spectrum requirements:[EN77] allocate, as soon as possible, an additional 12 MHz in major markets and an additional 6 MHz nationwide for existing public safety communications services; and an allocation of 25 MHz by 2000 and another 50 MHz by 2010 to facilitate implementation of new public safety telecommunications technologies. These future systems will support an increasing number of voice, data, graphics and video services to include dispatch/telephone interconnect, transaction processing, facsimile, snapshot, decision support, slow video and full motion video. The APCO analysis of spectrum requirements noted that the number of public safety licenses increased at a rate that approximately doubled the number of licenses in a 10-year period. We agree with APCO in this regard, and our analysis of dispatch spectrum requirements includes this factor when the additional dispatch spectrum requirements were evaluated.
Biomedical Telemetry Requirements
The biomedical telemetry users view the currently allocated bands as increasingly subject to noise and radio interference and that these bands may become unavailable over the course of the next ten years, as a result of the FCC spectrum "refarming" efforts. Reflecting these concerns, the House-Senate Conference Report on Title VI states,
"The Conferees note that advances in low power (e.g., below 5 mW) biomedical telemetry systems may greatly improve the quality and significantly decrease the cost of certain health care services. These systems are designed to operate in either the VHF or UHF bands. The Conferees believe that the NTIA and the FCC should carefully consider the needs of hospitals and other health care providers for interference-free radio spectrum in their respective allocation decisions made pursuant to this Act."[EN78]
Subsequent to enactment of Title VI, representatives from the biomedical telemetry industry[EN79] further clarified industry spectrum needs, specifically stating a need for an allocation of 12 MHz. Other Requirements
The Department of Justice indicated that the 162-174 MHz and 406-420 MHz bands are inadequate for many law enforcement purposes.[EN80] TIA indicated that land mobile services deserve a proprietary position in allocations of additional spectrum.[EN81] The LMCC supports efforts to make additional spectrum available for private land mobile use.[EN82]
The Coalition of Private Users of Emerging Multimedia Technologies (COPE) has filed a petition for rulemaking, requesting the FCC to allocate 75 MHz of spectrum, in aggregate, to establish a Private Land Mobile Advanced Communications Service.[EN83] The petition indicates that there is a need for spectrum for new services that will not and/or cannot be provided via carrier-based services such as PCS. The regulatory scheme adopted for PCS makes it impractical for private users to obtain and use their own PCS license for the new telecommunications technologies they need.[EN84] Further, the petition indicates that many of these services will require wide-band spectrum allocations for high-speed transmission of images and other specialized applications and existing PLMR allocations are insufficient to accommodate these new technologies.
In order to estimate future spectrum requirements, it is first necessary to estimate the growth of various land mobile services. Figure 1-3 presents historical data of growth trends for the Federal Government and PLMR services relative to 1984 levels of assignments or transmitters. Federal statistics include both conventional and trunked systems. Assuming linear growth, the number of conventional dispatch assignments and transmitters will nearly double in the next ten years. This represents a growth rate of two over the 10-year period. Figure 1-4 projects the number of cellular and paging subscriptions for selected years out to 2003. Historical data is combined with forecasts provided by PCIA. PCIA estimates that the number of paging subscriptions will increase by 94 percent from 1993 to 1998, and by 77 percent from 1998 to 2003. Cellular subscriptions are expected to increase by 154 percent from 1993 to 1998, and 58 percent from 1998 to 2003.[EN85] Assuming linear trends, the growth factors for paging and cellular over the 10-year period are estimated to be approximately three and four, respectively.Figure 1-3. Growth of dispatch radio relative to 1984 levels.
Figure 1-5 identifies PLMR trunking growth in the 800 MHz and 900 MHz bands. Assuming linear growth, extrapolation indicates that the number of licensed trunking transmitters will nearly double over the next 10 years. This represents a growth factor of approximately two for the 10-year period for these uses. Figure 1-6 identifies SMR/ESMR growth for the following years: 1993, 1998, and 2003. PCIA estimates that the number of SMR/ESMR subscriptions will increase by a factor of six over a 10-year period.[EN86]Figure 1-5. PLMR trunking growth.
Spectrum Forecasting in the Land Mobile Service
Spectrum forecasting, particularly in the land mobile services, is a difficult task because of the number of current initiatives, issues, and possible actions that could occur in the future. After reviewing the comments from the Inquiry, responses from many FCC proceedings on land mobile issues,[EN87] and the possible need for additional public safety allocations, we conclude that additional spectrum will be necessary to accommodate increasing use of both Federal and non-Federal land mobile services.
An estimate of spectrum requirements for the next 10 years is developed using the data of Figures 1-3, 1-4, 1-5 and 1-6. In this estimate, assumptions are made regarding the growth of land mobile use, the effect of new technology on spectrum use, and the conversion rate of current systems to the new technology. Further, the approach taken results in spectrum requirements that do not necessarily assure complete satisfaction of all spectrum needs, but rather estimate the spectrum required to approximate the same level of spectrum availability as currently exists. Therefore, the spectrum requirements projected herein are intended to indicate the spectrum required to accommodate current and new users, so that in 10 years the level of spectrum availability will be approximately the same as today. That is, if the estimated requirements are accurate, and the additional spectrum is allocated, then the land mobile bands (including new spectrum) in the year 2004 would be no more congested than currently allocated bands are.
Several factors need to be addressed concerning the spectrum requirements. Most commercial land mobile users may not have a preference (as long as service rates are competitive) concerning the manner in which telecommunications services are provided (i.e., whether the means are via satellite, cellular telephone, or PCS). Further, some proposed communications systems have not been fully developed, and involve technological challenges that may require significant time to successfully implement. Additionally, it is likely that some future Federal communications will be satisfied through commercial facilities such as cellular telephone, PCS, and SMR's.[EN88] For these reasons, the requirements should be viewed as general telecommunication requirements and not necessarily as a requirement to support a specific service. A number of possible implementation regimes, technology complexities, and range of environments makes it difficult to develop a single spectrum requirement number.
It is assumed that technologies implemented today (narrowbanding, digital multiple-access techniques) will have some impact on the current spectrum infrastructure over the next 10 years. Federal plans to rechannelize the 162-174 MHz band require that all new equipment procured after 1995 be narrowband equipment, and by 2005, all equipment must be narrowband. The FCC's proposed refarming initiative would eventually require all equipment to operate in narrowband channels in the 2004-2012 time frame, depending on market areas. Also, dual-mode cellular telephone equipment will be able to access both analog and hybrid/digital systems. While the FCC's current refarming proposal requires a transition to 6.25 kHz or 5 kHz channels in major markets within 10 years, comments to the FCC from manufacturers indicate this would be difficult to accomplish.[EN89] For the purposes of this study, and recognizing that the FCC rulemaking is not complete, it is assumed that complete narrowbanding of non-Federal channels will be fully implemented for 12.5 kHz channels by the year 2004. Federal narrowbanding will be implemented at 12.5 kHz channels at different times for the various Federal mobile bands.
Calculation of Spectrum Requirements
Estimates of spectrum requirements are defined in Table 1-1. The projected 10-year spectrum requirement is for national (Federal and non-Federal) land mobile services, excluding requirements for special applications such as military tactical and training use. In predicting long-term requirements, various parameters such as the conversion of systems to more efficient ones (called the conversion factor) and the effect of introducing more efficient technologies (called the technology factor) have been assumed for this analysis.
Table 1-1 identifies five main types of land mobile operations: dispatch, non-dispatch, 2 GHz PCS, SMR/ESMR, and other emerging mobile services. Dispatch-type operations include the conventional and trunked land mobile radio systems such as those within the Federal and PLMR services providing primarily voice communications. These services combined have approximately 100 MHz of assignable spectrum for conventional use. Private sector trunking, excluding SMR systems, operates within the 806-824 MHz, 851-869 MHz, 896-901 MHz, and 935-940 MHz bands (19 MHz).[EN90] Although Federal trunking can be established in any band allocated for mobile operations, commercial equipment currently is being used primarily in the 406.1-420 MHz band (14 MHz). Since Federal trunking can be performed in any band allocated for mobile use (unlike the PLMR services that have dedicated trunking bands), this 14 MHz is included in the 100 MHz indicated for conventional use.
Non-dispatch operations include one-way calling systems such as radio paging (5 MHz) and new services such as the 900 MHz advanced messaging services (3 MHz).[EN91] Two-way operations include cellular radiotelephony which has 50 MHz in the 824-849 MHz and 869-894 MHz bands. SMR/ESMR systems operate within portions of the 800 MHz and 900 MHz bands (19 MHz). The emerging 2 GHz PCS includes licensed and unlicensed PCS devices, which total 140 MHz of spectrum.
Current 10-Year Calculated Technology Conversion Additional Service-type Allocated Growth Additional Factor [b] Factor [c] Spectrum Spectrum Factor Spectrum Needed Requirements (MHz) (MHz) (MHz) ____________________________________________________________________________________________________ Dispatch conventional 100 2x 100 .50 .65 18 trunked 19 2x 19 .33 .25 3 Non-dispatch one-way [d] 8 3x 16 .50 .25 7 two-way [e] 50 4x 150 .33 .50 33 2 GHz PCS [f] 140 - 0 - - 0 SMR/ESMR 19 6x 95 .17 .50 8 Others [g] - - 135 - - 135 Total land mobile spectrum = 204 a Tabulated spectrum values illustrate only the method by which the total spectrum required was derived; each individual service will not necessarily require the amount indicated. All values are rounded to the nearest whole number. b Multiplier that accounts for increased spectrum efficiency from technologies such as narrowbanding and digital multiple-access techniques. c Multiplier that represents the percent of current spectrum converted to more efficient use. d One-way calling services include the current paging services plus other new services intended to receive informational transmissions, such as data and electronic-mail (i.e., advanced messaging). e Two-way services include the conventional cellular telephone services intended to operate over a wide area, plus other new services that will operate over larger distances, primarily to vehicles providing data and graphics transmissions along with voice. f PCS is defined by the FCC as "a family of mobile or portable radiocommunications services which could provide services to individuals and business, and be integrated with a variety of competing networks." The precise form of PCS is still evolving. g Other radiocommunications services include ITS, and advanced private-dispatch operations such as transaction/decision processing, facsimile, snapshots, slow and full motion video, and remote file access. The requirements identified for ITS in this chapter exclude spectrum for collision avoidance radars.
Other emerging mobile uses include ITS, and advanced private dispatch operations such as transaction/decision processing, facsimile, snapshots, slow and full motion video, and remote file access. The concept of ITS is still evolving, but it is envisioned to provide traffic information over a wide area. The use of two-way telephony and unlicensed PCS may be a component of the ITS concept.
The methodology used to compute the Additional Spectrum Requirement is illustrated in the following discussion for the conventional dispatch operations. Other service requirements identified in Table 1-1 would follow in a similar manner.
The 100 MHz of spectrum allocated to Federal and non-Federal conventional dispatch operations is listed in Table 1-2 below.
Frequency Dispatch Spectrum Allocation Bands_________________________________________________ 25-50 MHz 19.4 MHz Federal, non-Federal 138-150.8 MHz 8.7 MHz Federal 150-174 MHz 19.8 MHz Federal, non-Federal 220-222 MHz 2 MHz Federal, non-Federal 406.1-420 MHz 13.9 MHz Federal 450-512 MHz 28 MHz non-Federal 800 MHz 8.4 MHz non-Federal Spectrum: 100.2 MHz
As was stated previously, Federal land mobile assignments could double in the next ten years, as could the number of licensed PLMR transmitters. Therefore, it is assumed that twice as much spectrum would be needed to accommodate these assignments or transmitters in order not to exceed current spectrum congestion. This growth rate is reflected as a factor-of-two entry in the 10-year growth rate column of Table 1-1. This would result in a requirement for an additional 100 MHz if the new spectrum were used in the same manner as the current spectrum allocation. This additional 100 MHz is indicated under the "Calculated Additional Spectrum Needed" column.
However, it is expected that the use of any new spectrum allocation would involve the application of newer, more efficient narrowband technologies that would provide for twice the users in the same spectrum space. This effect is reflected as a technology factor and is 0.5 for conventional dispatch operations. That is, the communication service that presently uses one unit of bandwidth will require one-half unit in the future because of technological advances (i.e., narrowbanding). Taking into account only the technology factor, the spectrum requirement is reduced to 50 MHz (100 MHz multiplied by 0.5).
If all users were to convert to newer technologies immediately upon adoption of a rulemaking, there would be little need for additional spectrum in the short term. However, there will be a time period when systems are in the process of being converted. The length of this time period is influenced by certain factors such as amortization of current systems, availability of new systems, and the need for frequency coordination among users in common geographical areas. The amount of current spectrum estimated to be converted to narrowband use is indicated by a conversion factor and is shown in Table 1-1.
In the case of dispatch operations, it is assumed that all systems achieve 12.5 kHz channel usage at the prescribed time, and that system conversion to narrow channels will be linear during the conversion period. The results of an analysis indicate that spectrum shortfalls will occur during the 10-year period, with a maximum shortfall of about 18 MHz during the 1997-1998 time frame. At the end of the 10-year period, however, only an additional 6 MHz will be needed. Using the maximum value of spectrum shortfall, an equivalent conversion factor of 0.65 was calculated.[EN92] If the non-Federal channels are narrowed to 6.25 kHz or 5 kHz, as proposed in the NPRM, it is expected that no additional spectrum would be required for this service (additional spectrum requirement equal to zero in Table 1-1).
For dispatch operations, it is estimated that 65 MHz (100 MHz multiplied by 0.65) of the currently allocated spectrum will be effectively converted to the new technology by the end of the 10-year period. However, not all of this 65 MHz can be applied to new requirements since the radiocommunications requirements of current systems still need to be satisfied in this spectrum. Thus, an amount of spectrum equal to the converted spectrum times the technology factor must be used to satisfy present users, and is not available to satisfy new requirements. For this case, this value would be 32.5 MHz (65 MHz multiplied by 0.5), where 0.5 is the technology factor.
In this analysis, the additional spectrum needed under current conditions (Sadd) is equal to the current spectrum (Scurr) multiplied by the 10-year growth factor (F) less Scurr. If (R) is the future spectrum requirement, and only new systems were to use new technology (no conversion of existing systems), then Sadd(T) additional spectrum would be needed, where (T) is the technology factor. However, as current systems are converted to new technology, Scurr(C)(1-T) spectrum becomes available for assignment to new systems, where C is the conversion factor. The requirement for additional spectrum (R) at the end of the 10-year period is therefore reduced by the amount Scurr(C)(1-T). The equation for future spectrum requirement (R) is then equal to Sadd(T)-Scurr(C)(1-T), as shown below.
Applying the equation to the conventional dispatch case, Scurr and Sadd are both 100 MHz. Solving the equation for the required spectrum R, where the technology factor T is 0.5, and the conversion factor C is 0.65, results in approximately 18 MHz of additional spectrum required, as shown in Table 1-1.
For trunked dispatch operations, Figure 1-5 illustrates the growth that private sector trunking has experienced. As described earlier, this represents a growth factor of nearly two for the 10-year period. Therefore, it is assumed that twice as much spectrum will be needed to accommodate twice as many transmitters in order not to exceed current spectrum congestion. This would result in a requirement for an additional 19 MHz if the new spectrum were used in the same manner as the current spectrum allocation. It is further assumed that digital trunking systems will provide a three-to-one increase in capacity over current trunked systems[EN93] and that 25 percent of current trunked systems will convert to more efficient systems within 10 years. When these parameters are applied to the above equation, the estimated 10-year additional spectrum requirement is evaluated to be 3 MHz as shown in Table 1-1.
Spectrum requirements for dispatch operations are expected to be satisfied when the FCC refarming and the NTIA narrowband programs are complete. The additional dispatch spectrum required shown in Table 1-1 is a short-term requirement occurring only during a portion of the 10-year period of this forecast.
For two-way non-dispatch operations, the current cellular radiotelephone systems are used as a model to formulate a basis for which the end result is derived. As implied by the growth curve in Figure 1-4, it may therefore take 4 times as much spectrum to satisfy the demand for cellular telephone services. Thus, the extrapolated spectrum requirement, assuming today's technology, would show an increase of 150 MHz that would be required so as not to exceed the same level of congestion for cellular-like services. Current digital systems provide a three-to-one increase in capacity. For planning purposes, a nominal three-to-one increase is assumed for this analysis. Therefore, only one-third of the spectrum (or 50 MHz) will be required to support the cellular demands. For the purposes of estimation, it is assumed that 50 percent of cellular systems will convert their current systems to much more spectrum-efficient systems over the 10-year period. Taking this into account, the estimated 10-year additional spectrum requirement is reduced to 33 MHz. One-way calling services include the current paging systems plus other new advanced messaging services such as data messages, fax, voice paging, and wireless E-mail. As implied by the graph in Figure 1-4, it may take three times as much spectrum to satisfy the demand for non-dispatch, one-way services. The extrapolated spectrum requirement, assuming today's technology, would show an increase of 16 MHz that would be required so as not to exceed the same level of congestion. Assuming a technology factor of 0.5, which is supported by increases in data rates, and a conversion factor of 0.25, reduces the 10-year requirement to 7 MHz as indicated in Table 1-1.
Personal Communication Services
The FCC has allocated a substantial amount of spectrum in the 2 GHz band for new PCS. The FCC allocated a total of 140 MHz at 1850-1990 MHz. Licensed PCS were allocated 120 MHz, while unlicensed PCS devices were allocated 20 MHz. It is assumed that the amount of PCS spectrum (140 MHz) that the FCC has allocated is sufficient for the 10-year period. Therefore, no additional spectrum will be required over the 10-year period.
Figure 1-6 identifies the anticipated growth of SMR/ESMR's - it represents a growth of six-to-one over the 10-year period. The extrapolated spectrum requirement, assuming today's technology, would show an increase of 95 MHz of additional spectrum that would be needed. ESMR systems are expected to provide a six-to-one increase in capacity over SMR's.[EN94] Therefore, only one-sixth of the spectrum will be required. For estimation purposes, it is assumed that 50 percent of this spectrum will be used by more efficient systems within 10 years. Using the above equation, the estimated 10-year requirement is then reduced to 8 MHz.
Other Land Mobile Services
Other service-types include ITS and advanced, private-dispatch operations.
In its Strategic Plan, IVHS AMERICA (now ITS AMERICA) recognized it must define RF spectrum needs and obtain appropriate spectrum allocations. In response to our Inquiry, IVHS AMERICA could not further identify in detail spectrum requirements necessary to implement the nationwide ITS infrastructure envisioned in its Strategic Plan. It also could not at that time identify whether the backbone ITS communications system that would support the ITS infrastructure would require dedicated ITS spectrum. Answers to these questions are being pursued through pilot projects, laboratory and field research, and testing.[EN95]
Present ITS requirements are being accommodated within currently allocated spectrum in defined radio services, primarily in the 902-928 MHz band. Additional ITS functions, such as radar collision warning, will require spectrum in other bands. Further, certain ITS functions may be carried out in the context of new PCS services and in conjunction with wide-area broadcasting services.
The DOT and ITS AMERICA have indicated that access to additional spectrum will be required for ITS services. Although spectrum requirements for the ITS are still being defined, DOT has identified requirements in several frequency bands to support ITS functions.[EN96] Requirements for land mobile spectrum totaled 145.1 MHz, of which 100 kHz is presently authorized for ITS use. Sixty megahertz of this was for transitional use, and was subtracted to determine the long-term requirement. Noting the requirements are still being defined within the ITS community, we list 75 MHz below 10 GHz for short-range vehicle-to-roadside communications and toll collection, and 10 MHz between 10 GHz and 100 GHz for data links associated with collision avoidance radars. Eighty-five megahertz of spectrum for ITS (excluding spectrum for collision avoidance radar systems) has been included in the "other" category of Table 1-1.
COPE has filed a petition for rulemaking, requesting the FCC to allocate 75 MHz of spectrum, in aggregate, to establish a Private Land Mobile Advanced Communications Service.[EN97] The petition states that there is a need for additional spectrum for new services that will not and/or cannot be provided via common carrier-based services such as PCS. Further, the petition states that many of these services will require wide-band spectrum allocations for high speed transmission of images and other specialized applications, including public safety functions.
APCO, in comments to the FCC, stated that public safety services will require an additional 25 MHz by the year 2000, and another 50 MHz by 2010.[EN98] The APCO spectrum requirements are identical to the COPE petition in that 75 MHz was requested for advanced private land mobile applications. We have carefully reviewed these comments and agree that additional spectrum is needed for advanced wireless services such as transaction/decision processing, facsimile, snapshots, slow and full motion video, and remote file access for both public safety and industrial applications. Some of the requested spectrum is included in our assessment of general dispatch and two-way non-dispatch spectrum requirements. Our review indicates that approximately 50 MHz of additional spectrum is required to satisfy requirements for advanced private land mobile applications not previously addressed. It is expected that this 50 MHz would be shared between public safety and industrial uses, with public safety use primarily within urban areas, and industrial use primarily outside of these areas.
Having estimated that 85 MHz is needed for ITS and 50 MHz is necessary for advanced private operations, a total of 135 MHz is included as "Other" in Table 1-1.
A Second Approach to Spectrum Estimation
NTIA requested PCIA to estimate PCS requirements. The PCIA PCS Technical and Engineering Committee derived estimates of clear spectrum required to support PCS services (2 GHz PCS, cellular, ESMR) in the year 2003.[EN99] This report is an update of previous 1992 PCIA reports on spectrum.[EN100]
The methodology employed was a "bottom-up" approach, using estimated traffic loads for the services studied, considering the requirements of voice, data, imagery, and messaging as codified in the market demand research.[EN101] Implementation environments for low, medium, and high geographic densities of cells and population were considered. Included in the calculations were certain assumptions for cell spacing, grade of service, user busy hour traffic statistics, bearer channel bandwidths, and PCS infrastructure buildout. Based on an assumed number of 10 service providers per area, the report concludes that in the year 2003, the required spectrum for the PCS services of cellular, ESMR, and licensed 2 GHz PCS will be between 340 and 399 MHz.
NTIA agrees with the PCIA approach, but believes that urban in-building coverage would most likely be satisfied generally by either wireline or unlicensed wireless systems in the next 10-year period, and that spectrum efficiency is of such importance that cell reuse factors should be no more than seven. Using the PCIA model with a low/medium-density cell infrastructure and a cell reuse factor of seven, the PCIA model yields a spectrum requirement of approximately 216 MHz. This is compared with the NTIA estimation of 230 MHz for similar PCS-type licensed services determined by adding the "current allocated spectrum" and "additional spectrum requirements" column entries for licensed 2 GHz PCS, cellular (two-way non-dispatch), and SMR/ESMR services.
For paging services, a similar forecast was prepared by PCIA that included four paging applications: one-way, two-way, asymmetrical, two-way symmetrical, and high-speed voice. PCIA concluded that 35 MHz would be required to support these four services.[EN102] NTIA agrees, in general, with the forecasts for the first three paging services mentioned. Comments to our Inquiry did not provide sufficient data to conclude that high-speed voice paging will be a significant service within the 10-year period. Therefore, we cannot concur with the spectrum requirement for high-speed voice paging at this time.
Additional Spectrum Needed
All services, when totaled, show a calculated value of 204 MHz of additional spectrum that may be needed for the land mobile services. It must be recognized that many of the values used in the derivation of spectrum requirements are estimates that vary over a range of values. To illustrate the effect on the estimated 10-year requirements and as an example, values such as growth rate, technology and conversion factors were increased or decreased by 10 percent. In the first case, the growth rates and technology factors were decreased by 10 percent, and the conversion factors were increased by 10 percent. Changing these values in concert will produce the greatest decrease in the estimated spectrum requirements. Thus, the estimated 10-year requirement is reduced nearly 43 MHz from 204 MHz to 161 MHz. Conversely, when growth rates and technology factors were increased by 10 percent, and conversion factors were decreased by 10 percent, the greatest increase in the estimated spectrum requirement is produced. Again, this yields a difference of nearly 43 MHz from the initial estimate of 204 MHz, resulting in a requirement of 247 MHz.
Clearly, such a variation illustrates the sensitivity of the end result on these input factors. If one or more of these parameters changes significantly, (which is not unexpected with today's technologies, service offerings, or demands) the overall spectrum requirement forecasted changes significantly. The fast pace of technology, the need to have instant communications, and world events make predictions beyond five years a speculative effort. Therefore, long-term planning, particularly in the land mobile services, should be re-evaluated on a continuing basis and adjusted, if necessary. By doing so, more current demands and technologies can be considered to provide a better estimate of requirements that will be needed to satisfy any demands.
Furthermore, recent spectrum legislation has required a transfer of at least 200 MHz of spectrum from the Federal Government to the private sector.[EN103] The 200 MHz will be used to satisfy some of the future land mobile service requirements.[EN104]
In summary, assuming that the FCC rulemaking on refarming is completed, current cellular and SMR systems are partially replaced by much more efficient digital systems, and NTIA implements the narrowbanding of the Federal land mobile bands, there remains an estimated requirement of approximately 204 MHz for land mobile use in the next 10 years. However, the variabilities associated with this particular analysis imply the requirement could range from 161 MHz to 247 MHz.
Aeronautical Mobile Service
The aeronautical mobile service is "[a] mobile service between aeronautical stations and aircraft stations, or between aircraft stations, in which survival craft stations may participate."[EN105] The aeronautical mobile service supports voice and data communications between ground stations and aircraft or between aircraft including flight testing, telecommand, airdrome control, and route (R) and off-route (OR) services.[EN106] Many of the communications within this service are used for air traffic services (ATS) and aeronautical operational control (AOC) safety communications.
The aeronautical mobile service, including certain frequency bands and technical standards used for this service, are coordinated internationally through the International Civil Aviation Organization (ICAO) to ensure the worldwide interoperability of these services. Consequently, many of the regulations found in Part 87 of the FCC Rules and the NTIA Manual are based on ICAO standards.
Many aeronautical mobile communications are used by Federal and non-Federal agencies in identical ways and are accommodated in the 2-23 MHz (HF) and 118-137 MHz (VHF) bands. Additionally, the Federal Aviation Administration (FAA) provides air traffic control (ATC) services to military aircraft on allotted frequencies in the 225-400 MHz band.
The HF band includes 21 frequency ranges that are shared equally by Federal and non-Federal users for ATC and AOC functions. These bands, regulated by international agreement, have long provided the major means of communications with aircraft in transoceanic service.[EN107] Because HF signals propagate terrestrially over long distances, HF radio provides most communications with aircraft over ocean routes and in some developing countries. HF is not used over the United States, except in Alaska.
The VHF band provides the primary communications mode for ATS and AOC safety communications for all areas of the world where radio line-of-sight (LOS) services can be established in a practical manner.[EN108] This band is used by civil aviation authorities to provide ATS safety communications and by the airlines, business aviation, and general aviation to provide AOC safety communications. Each communications frequency is re-used as often as possible due to the limited number of available frequencies. The FAA and Aeronautical Radio, Inc. (ARINC)[EN109] maintain an extensive network of VHF radio stations giving reliable coverage over the United States and off-shore areas.
Civil Aviation Uses
The commercial airlines, private, and general aviation communities depend upon radiocommunications to foster the safe, economic, and efficient operation of aircraft, which includes ATS, AOC, aeronautical administrative communications (AAC), and aeronautical public correspondence (APC) services.
ATS communications include ATC, communications providing alphanumeric and graphical weather data, and communications intended to notify appropriate organizations regarding aircraft in need of search and rescue, and to aid and assist such organizations as required.
AOC communications are used to initiate, continue, divert, or terminate a flight in the interest of the safety of the aircraft, and the regularity and efficiency of a flight. AOC functions operate via air-ground voice and data communications either through the cockpit crew or directly with airborne sensors or systems. In 1977, the Aircraft Communications, Addressing, and Reporting System (ACARS) was introduced. ACARS is an air-ground digital packet radio system operating in the VHF band, providing service over most of North America. ACARS has resulted in significant improvements in spectrum efficiency by removing routine communications from voice and replacing them with data messages. ARINC notes that "the system continues to grow, and ACARS now handles close to seven million messages a month with an availability at critical airports of 99 percent."[EN110]
Both AAC and APC are non-safety services and have priorities below ATS and AOC. AAC includes cabin provisioning and inventory, seat assignments, passenger travel arrangements, and baggage and parcel tracing. APC services include voice telephone service for passengers to connect with ground-based networks worldwide. These common carriers allow passengers onboard many commercial aircraft to place telephone calls while in flight. These systems operate in the 849-851 MHz (ground-air) and 894-896 MHz (air-ground) bands.[EN111] Although initial voice services were provided with 6 kHz-bandwidth Amplitude Compandored Single-Side Band (ACSB) circuits, improved services will be offered with digital technology and highly-efficient vocoders, including data and facsimile.
The FAA provides air-ground communications support for enroute, terminal, and flight services[EN112] to end users such as the commercial airlines, general and private aviation, the military services and law enforcement agencies such as the Drug Enforcement Administration and the U.S. Customs Service. The Federal Government's use of aeronautical communications plays an important part of national defense. The FAA provides ATS to the military services on allotted frequencies in the 225-400 MHz band. The military services make extensive use of the 225-400 MHz band, which helps to avoid impacting national airspace air-ground communications.
Federal Government aeronautical mobile requirements are also accommodated in the HF and VHF portions of the radio spectrum and are used to provide aviation services to commercial airlines and general aviation. Over 90 percent of the Federal HF spectrum use is accounted for by the Air Force and Navy, while the FAA accounts for over 80 percent of the VHF spectrum use in its support to aeronautical mobile requirements of the flying public. DOD uses the HF band for a variety of functions, including but not limited to, tactical air-ground communications, command and control communications, and for communications supporting disaster relief operations. HF communications is the only communications means available between DOD aircraft transiting oceanic regions and many continental land masses lacking in other modes of communications. Some specific examples[EN113] of HF aeronautical mobile service spectrum include National Aeronautics and Space Administration (NASA) support of the space shuttle operations. The U.S. Air Force uses HF for global command and control stations, flight testing, tactical communications, data coordination and satellite recovery operations. The U.S. Navy utilizes HF aeronautical mobile spectrum for close air support, tactical support for anti-submarine warfare communications, and training. The Army uses the 30-88 MHz and 138-150.8 MHz bands for close air support training with ground troops via air-ground communications. The DOD has stated that the "30-88 MHz band is vital to tactical mobile communications."[EN114]
Federal agencies make extensive use of the 225-400 MHz band for aeronautical mobile operations. This band is used primarily for military functions, including air-ground communications and ATC for military aircraft.[EN115] The FAA provides ATC functions for military aircraft essentially identical to the ATC communications in the VHF band. In fact, in most areas the FAA transmits ATC information simultaneously on VHF and UHF channels for military aircraft not VHF-equipped so that military aircraft remain aware of civilian aircraft, and vice versa. Military uses include, but are not limited to, coordination of in-flight refueling, vectoring of aircraft to targets, and large scale training exercises. Military ATC (i.e., ground control, approach control, training flights, combat, etc.) would typically use UHF exclusively.[EN116] The FAA, Air Force, Army and Navy account for nearly all of fixed and mobile spectrum use in this band.
There are aeronautical systems operating under the more general mobile service allocation. These systems operate above 1 GHz and generally provide non-voice communications referred to as telemetry, data, and video links. The main categories of mobile systems that involve aeronautical mobile operations are described below.
Air Combat Training (ACT) systems are more complex by nature of their operation, as both fixed and aeronautical mobile equipment are used. The military uses them at more than 21 sites across the United States to provide realistic tactical simulation and pilot training in a peacetime environment. Training is provided in air warfare operations and maneuvers without actually firing weapons. The systems provide real-time altitude, location, velocity, angle of attack, simulated weapon status, and other data on participating aircraft. A typical configuration for a system consists of a master control station, six or more remote tracking stations and up to 24 participating aircraft. Aircraft altitude of up to 35,000 feet is typical during exercises that may last for up to ten hours per day. Recent system upgrades provide for multiple control stations and up to 36 aircraft. These are tied together via radio links, nine or ten of which are required for each system. The 1760-1840 MHz frequency range supports this type of operation.
Air-ground video systems primarily provide real-time television displays from cameras on aircraft, typically flying at 10,000 to 15,000 feet. Some typical functions include video images of missile, drone, and remotely piloted vehicles testing, flight testing of new aircraft, and airborne monitoring of civil disturbances. The majority of operations are on the military test ranges. The most widely used bands for the air-ground video telemetry operations are the 1710-1850 MHz, 2200-2290 MHz, and 4400-4990 MHz bands.
The Federal Government uses various telemetry systems to support a variety of test flight and equipment development functions. The 1435-1525 MHz and 2360-2390 MHz bands support these functions at nine major military and NASA test ranges/centers and numerous smaller facilities. These bands are the most important aeronautical flight test telemetry bands in the United States.[EN117] A number of complex and organizationally independent functions must be successfully coordinated to complete a mission. Examples of some of these are: range safety (e.g., flight termination capability and clearing the range of non-participants); chase aircraft; weather; measurement support (e.g., radar and recorders); target drone aircraft; nominal test system operation; and aeronautical telemetry support.
The DOD operates a variety of radio-based target scoring systems (airborne and seaborne) for training and weapons testing purposes. Because of the need to maintain a high level of combat readiness, these systems are tested on a regular basis. Currently, the airborne training activities are at recognized national test ranges. In recent years, the target scoring systems have become quite complex and provide multiple functions, such as: indicating whether a target was hit, how much of the target was destroyed, projectile velocity, and target tracking. The frequency bands supporting these systems are the 1710-1850 MHz, 2200-2290 MHz, and 4400-4990 MHz bands.
Several forums have completed studies and are now pursuing the development and implementation of system improvements providing increased spectrum utilization efficiency and functional capability in the 118-137 MHz VHF air-to-ground communications band. Internationally, the ICAO Aeronautical Mobile Communications Panel (AMCP) undertook this work, beginning in 1991, as a result of recommendations of the 1990 ICAO Communications/Meteorological/Operations (COM/MET/OPS) Divisional Meeting. In the United States, RTCA[EN118] Special Committee 172 (SC–172) was established in 1991 through recommendations by the FAA and ARINC, to undertake a compatible, parallel effort from a U.S. Government/industry perspective. Both forums have examined a number of present and future system improvements. As a result of these coordinated studies, a 25 kHz TDMA system (four independent voice and/or data link circuits on each RF channel) was recommended for the future (beyond 2004) VHF air-ground system. The future system will result in a substantial gain in system capacity, and provide system functional improvements, including data links. The AMCP had concluded that an 8.33 kHz double sideband amplitude modulation (DSB-AM) voice/25 kHz VHF digital link (VDL) carrier sensed multiple access (CSMA) system was the only practical solution which could be implemented within the shortest possible time scale and meet the anticipated near-term ATS and AOC requirements in those areas where frequency congestion exists. The implementation date of this system is expected in 1998.
Video compression reduces the bandwidth of an existing analog or digital channel by eliminating redundant information.[EN119] Compression, when applied to air-ground video, could significantly reduce future spectrum requirements. Advances in digitized video compression and modulation technologies can place 10 or more video signals within the 6 MHz bandwidth normally occupied by a single analog video signal.[EN120]
Aviation communication requirements are complicated by the need to maintain a common communications and radionavigation infrastructure throughout the world. ARINC notes that the aviation community plans very carefully and establishes reasonable transition periods before obsolescent systems are phased out, and that planning looks at least a decade ahead.[EN121]
ARINC contends that future demands may not be accommodated fully within the current allocations and that additional spectrum may be needed in the future.[EN122] Although the DOD did not elaborate on their use of aeronautical communications specifically, they did indicate that "for the next 10 to 20 years, DOD use of the current military spectrum will remain essentially as it exists today."[EN123]
In their initial comments to our Inquiry, the FAA indicated that current spectrum would be adequate.[EN124] However, the civil aviation community is pursuing a network-based HF data link system to help satisfy future ATS and AOC communication requirements in oceanic areas in a cost efficient and reliable manner. The FAA estimates that about 36 frequencies, totaling 108 kHz (6 families of 6 HF frequencies each), will be needed to establish an initial worldwide service.[EN125] The FAA expects that aeronautical mobile-satellite (R) services will provide a significant communications enhancement in oceanic areas. While there may be some future reductions in requirements for HF aeronautical mobile (R) voice services because of the continued implementation of the aeronautical mobile-satellite (R) service capability, such a reduction is not expected within the next 10 years.[EN126]
Many of the aeronautical communications requirements, including those for transoceanic flights and public correspondence, could be satisfied through satellite-based systems. The U.S. and international civil aviation communities have recommended a combination voice/data system to satisfy future VHF air-ground communication requirements. Furthermore, some of the aeronautical voice traffic will be supplemented by more efficient digital links. However, the continuing and unavoidable growth of air-ground voice and data circuit requirements is expected to maintain pressure on the FAA's frequency resources in this band despite the alleviatory effects of new technologies.
The United States Coast Guard (USCG) has indicated that 2 additional channels per band are needed for aeronautical mobile (OR) voice communications, particularly below 10 MHz.[EN127] There are 5 bands below 10 MHz allocated on a primary basis to the aeronautical mobile (OR) service: 3025-3155 kHz, 4700-4750 kHz, 5680-5730 kHz, 6685-6765 kHz, and 8965-9040 kHz. Therefore, 30 kHz of additional spectrum may be needed.
Further, the USCG indicated that additional HF spectrum would be needed for wideband mobile requirements such as imagery, etc.[EN128] NTIA finds that, as an initial estimate, 100 kHz of spectrum would be needed for such services.
In summary, we find that 108 kHz of additional HF aeronautical mobile (R) service spectrum will be needed over the 10-year period. There also appears to be a requirement over the 10-year period for 30 kHz of additional HF spectrum for aeronautical mobile (OR) uses, and a requirement for 100 kHz of additional HF mobile service spectrum used in support of aeronautical operations.
Maritime Mobile Service
The maritime mobile service is "a mobile service between coast stations and ship stations, or between ship stations, or between associated on-board communication stations."[EN129] In addition, emergency position-indicating radiobeacon and survival craft stations may also participate in this service.
The maritime community has been a pioneer in the use of wireless communications. As early as 1900, radios were being installed aboard ships to receive storm warnings transmitted from stations on shore. Today, the maritime mobile service provides a wide range of communication services to vessels operating in international waters, coastal areas, and inland lakes and waterways. These services provide a means of communications for the day-to-day activities of the maritime industry as well as providing a critical safety link for the protection of lives and property. Such uses include ordering ships' stores, ship command and control, inquiring about berthing facilities, making personal and business telephone calls, and changing schedules.
Because safety-of-life is a worldwide issue, compatibility among nations is a key concern. Therefore, many of the maritime standards are established by international agreements administered by the International Telecommunication Union (ITU) and the International Maritime Organization (IMO). The ITU and IMO regulations are the basis for many of the regulations in the NTIA Manual and in the FCC Part 80 Rules.
For most purposes, Federal and non-Federal users share the maritime frequencies and are accommodated in portions of the MF (300-3000 kHz), HF (3-30 MHz) and VHF (156-162 MHz) bands. Frequency bands below 30 MHz are used for a wide range of services.[EN130] Many of the channels are established and regulated by international agreement and are available for distress, urgency and safety, digital selective calling (DSC),[EN131] narrow-band direct-printing (NBDP),[EN132] facsimile, public correspondence, private communications, etc.
VHF channels in the 156-162 MHz band provide short-range ship-ship or ship-shore communications. Channels are made available according to the type of communication and the nature of the ship's operation. For example, channels are available for safety communications, distress and calling, control of ship movement, environmental, etc. Also, channels are available for public correspondence and private communications. Although not used extensively, data communications are also available on various channels, subject to special arrangement among interested and affected administrations. Many of these frequencies are specified on an international basis.[EN133]
The 216-220 MHz band is allocated to the Federal and non-Federal users for the maritime mobile service on a shared, primary, co-equal basis. Channels are made available within the 216-220 MHz band for a system called the Automated Maritime Telecommunications System (AMTS).
Private entities that use maritime communications include commercial and non-commercial vessels, the U.S. Merchant Marine, international commercial traffic vessels, and port operators. National maritime mobile service allocations are administered by the FCC. Channels are available in the MF, HF and VHF bands according to the type of communication intended as described above.
Commercial transport vessels are ships that are used primarily in commerce for transporting persons or goods to or from any harbor or port or between places within a harbor or port area. Commercial vessels are also engaged in the construction, change in construction, servicing, maintenance, repair, loading, unloading, movement, piloting, or salvaging of any other ship or vessel.[EN134]
Non-commercial communications are used by recreational boaters and by vessels not intending to make a profit while in operation. Channels are available in the MF, HF and VHF bands according to the type of communications intended.
AMTS is an automatic, integrated, and interconnected communications system serving ship stations within the 216-220 MHz band. AMTS provides full-duplex voice and data public correspondence service to the maritime community similar to that provided by landline telephone systems on specific frequencies allotted to the AMTS. Calls may be placed to, from, or between vessels on a direct-dial basis without operator intervention. Currently, there is only one AMTS in operation, with service being provided by Waterway Communications System, Inc. (WATERCOM), a corporation set up by a number of barge and towing operators. The system of 55 base stations (100-115 km spacing) tracks ship locations so that incoming calls are routed through the nearest base station. This system operates along the Mississippi, Illinois and Ohio Rivers, providing service primarily to the tug and towboat industry from New Orleans to Minneapolis/St. Paul, Chicago and Pittsburgh, and along the Gulf Intracoastal Waterway from the Texas/Mexican border to the Florida panhandle.
Although not originally set up as a maritime service, cellular telephone is becoming the service-of-choice, especially for small boat owners not required by law to carry a VHF maritime mobile radio.[EN135] The USCG permits certain fishing vessels required to carry radio equipment for safety purposes to equip themselves with a cellular telephone in lieu of other radio equipment.[EN136] In the Gulf of Mexico, Petrocom operates an offshore cellular telephone service that provides voice and data services to vessels. In many areas, dialing "* CG" on a cellular telephone will immediately connect to the USCG. While this has the great advantage of providing emergency help to many boaters who would not have purchased a marine radio, it has the disadvantage of not allowing other nearby boats to hear a distress call and respond more promptly.[EN137] Cellular telephone has a more limited range than either of the other services (16 vs. 80 km). In addition, cellular telephone service tends to follow highways, rather than rivers or coastlines. Nevertheless, cellular telephone service is rapidly expanding and should be expected to play a greater role in coastal and inland maritime mobile services.
Federal maritime mobile communications support the operation, movement and safety of shipping on navigable waters of the United States and on the surrounding seas. The USCG has major responsibilities for maritime safety and navigation. Federal use of maritime mobile allocations must be in compliance with international and domestic regulations to ensure interoperability with all shipping and to maintain the integrity of maritime distress and safety communications.
The USCG relies on HF for command and control communications with cutters, aircraft, and shore facilities for purposes including search and rescue, off-shore enforcement of laws and treaties (including drug enforcement). Because of the USCG's expanding role in drug enforcement, a significant increase in the use of HF systems for air-ground and ship-shore circuits has taken place in the last decade. The USCG also relies on the HF band for such communications as distress and safety, broadcast of maritime safety information, emergency medical assistance communications, receipt of vessel position reports for safety purposes, and receipt of weather observation reports.
The Navy also has HF communication systems that transmit between shore stations and ships, and ship-ship in the maritime mobile bands. They support hydrographic surveys, communications with jumbo tankers, weapon system testing, and secure tactical voice systems. Constant communications with individual ships and naval forces at sea is required. Therefore, the Navy has a large investment and heavy reliance on HF communication equipment at shore installations and shipboard. HF transmissions will continue to be very important for fleet-wide communications. The Department of Interior uses HF for its U.S. Geological Survey organization. These systems support marine geology exploration and mapping tasks. The Department of Commerce has HF maritime mobile systems to support ships and boats used by the National Marine Fisheries Service and for communication links between major fishery centers and research vessels of the National Oceanic and Atmospheric Administration (NOAA) Corps fleet. The USCG also relies on VHF channels for ship-ship and ship-shore communications on a regular basis. The only exclusive Federal Government allocation for the maritime mobile service in the bands between 30-3000 MHz is at 157.0375-157.1875 MHz. This band consists of six 25 kHz channels. Five channels are used to support the National VHF-FM Distress and Safety System operated by the USCG. The remaining channel is used by Federal agencies as a working frequency for their maritime operations.
Maritime mobile service use in the Federal Government fixed and mobile bands between 30-3000 MHz primarily supports Federal agency requirements to interface with civil land and aeronautical mobile service operations.
In November 1992, the FCC issued an NOI/NPRM, with the intent of reviewing present requirements and future trends concerning maritime communications.[EN138] The information sought will assist in formulating rules and regulatory policies for the maritime services that will increase safety, promote flexibility, reduce congestion, and remove unnecessary impediments to the economic well-being of the maritime industry. An issue of particular importance addressed in the Maritime NOI is the use of narrowband channels (i.e., splitting the current 25 kHz VHF voice channels into 12.5 kHz channels).
To address the congestion problem in the VHF maritime band, the ITU Radiocommunications Sector Study Group 8 will be considering the use of narrowband channels during the 1995 time frame. The United States has submitted a draft report and recommendations to the study group on the subject suggesting the use of 12.5 kHz spacing using narrowband FM techniques. Commenters to the Maritime NOI indicated that voice telephony services, data communications, including facsimile, Electronic-Mail, video technology and position location will likely be future telecommunications requirements.[EN139] Many of the commenters supported narrowbanding of the VHF band in order to provide the spectrum for these services.[EN140]
The maritime mobile services provide a means of communications for the day-to-day activities of a multi-billion dollar industry as well as providing the critical safety link for the protection of life and property at sea.
The USCG indicated that "HF remains a needed, affordable and reliable communications medium for the foreseeable future."[EN141] Furthermore, the USCG stated that WARC-87 did not provide adequate spectrum for maritime requirements in the 4 and 8 MHz bands and, consequently, a severe shortfall (of spectrum) exists below 10 MHz.[EN142] The USCG further clarified this point by indicating that 6-10 additional channels per band below 10 MHz would be needed for maritime mobile voice requirements.[EN143] This would imply, for the 4 MHz and 8 MHz bands (with 3 kHz voice channels), that 18-30 kHz would be required per band, or 36-60 kHz total.
The Coast Guard indicated that it is essential for the maritime VHF band to be maintained for exclusive maritime use since it is vital to maritime safety and maritime interoperability on a worldwide basis.[EN144] Many of the commenters to the Maritime NOI indicated that narrowbanding the VHF band will allow for the expansion of increasing services. It is anticipated that any additional VHF maritime mobile spectrum requirements needed over the next 10-year period can be satisfied through the implementation of new technologies (such as VHF narrowbanding), and the increased use of land-based services.
In summary, NTIA estimates that 36-60 kHz of additional spectrum will be needed to satisfy HF maritime mobile requirements. No additional MF and VHF spectrum (provided VHF narrowbanding as discussed above is achieved) will be required for the maritime mobile services over the 10-year period.
The mobile-satellite service (MSS) is a "radiocommunication service between mobile earth stations and one or more space stations, or between space stations, or between mobile earth stations by means of one or more space stations."[EN145] MSS services meet the needs of many industries worldwide. They are ideal for international applications where rapidly-deployable mobile communications between countries are needed. Mobile-satellite communications to and from ships and aircraft greatly aid their safe operation. The use of land mobile-satellite terminals in times of emergencies to establish immediate communications is now being recognized as necessary.[EN146]
In the United States, MSS meets the needs of the transportation industry by providing communications links for systems that are able to track and monitor cargo, including hazardous materials.[EN147] Public safety needs, such as supporting fire fighting, search and rescue, and communications during disasters can also be met with MSS.
The FCC has authorized the operation of the first domestic mobile-satellite system, which will use portions of the 1500/1600 MHz band. This system will be operated by the American Mobile Satellite Corporation (AMSC). AMSC plans to offer services to not only cellular telephone consumers who do not have access to complete coverage from terrestrial cellular systems, but also to the maritime and aeronautical communities. AMSC's first satellite is due for launch in 1995; the satellite is to be placed in geostationary orbit in position to serve North America.
Aeronautical Mobile-Satellite Service
The International Maritime Satellite Organization (INMARSAT) is using geostationary satellites to provide voice and digital data circuits for transoceanic aircraft on an experimental basis, giving much more reliable and inclusive coverage than current HF radio circuits. This experimental program includes Automatic Dependent Surveillance (ADS), an important new air traffic control procedure based on the periodic reporting from aircraft of on-board navigation data. The initial use of ADS is being planned for oceanic areas. The aeronautical mobile-satellite service (AMSS) could also replace many HF links over land areas. ARINC stated that "In time, communications currently handled by HF radio will be transferred to satellite communications."[EN148]
Several commenters indicated that satellite-based services will play a greater role in future air mobile services. The aeronautical mobile-satellite (R) service (AMS(R)S) has the capability to provide air-ground communication service to areas that are not served by present air-ground facilities.[EN149]
Maritime Mobile-Satellite Service
INMARSAT is providing much-improved communications to larger ocean-going ships, which will tend to replace the use of long-range HF communications. INMARSAT provides distress, safety and general communication services. This system is currently used by approximately 17,000 ships throughout the world, including extensive operations within inland waterways for ship-shore communications. The number of users is expected to reach 40,000 within the next 10 years. Its use for distress and safety communications is part of the Global Maritime Distress and Safety System (GMDSS). This international application is tied to and required by international treaty resulting from the Safety of Life at Sea (SOLAS) Convention.
The size and cost of current INMARSAT shipboard installations currently limits its use by smaller vessels. However, future mobile-satellite service (provided particularly by low-Earth-orbiting satellites) would be expected to provide service to smaller vessels, including those in polar regions. Commercial and non-commercial maritime users can be anticipated to increasingly use MSS as availability improves and costs are reduced.[EN150] The USCG stated that satellite communications through the INMARSAT system are now coming into wide-spread use within the maritime service.[EN151]
Land Mobile-Satellite Service
The land mobile-satellite service (LMSS) is expected to be a crucial component of future personal mobile communications systems. One such system being studied by the ITU Radiocommunications Bureau is the FPLMTS. The objective of FPLMTS is to provide pervasive mobile communications by the year 2000. It is recognized that in low-traffic areas, or in areas where FPLMTS has not been implemented, communications could be provided by mobile-satellite systems as an integral part of the FPLMTS.
Other LMSS services include remote news-gathering, remote monitoring of pipelines, wells and environmental sensors, and delivery of health and emergency services to rural locations. Federal, state, and local government agencies have a need for intermittent-use of LMSS terminals when other communications systems may be unavailable. For many industries, such as interstate trucking, MSS may be used instead of terrestrially-delivered communications services. MSS has clear opportunities for providing service to remote areas in which cellular or PCS investment is not economical.[EN152]
Mobile-satellite services are expected to grow rapidly, including many applications for Federal agencies. For example, mobile-satellite communications is a current and growing requirement of U.S. military Command, Control, Communications and Intelligence (C³I).[EN153] Many Federal agencies are currently using INMARSAT services to satisfy a variety of telecommunications needs. Based on DOE's extensive land mobile service use and operations throughout the United States, DOE is planning to use mobile-satellite services for navigation, identification, location, and tracking of vehicles transporting nuclear materials.[EN154] The newly-allocated MSS systems, including low-Earth-orbiting (LEO) satellites, will be incorporated into the array of commercial communication resources available to the military.[EN155]
The spectrum requirements expressed for MSS to date are primarily for voice services, along with a growing amount of data. However, it is likely that graphic and video data will also be transmitted over MSS systems. For example, APCO[EN156] envisions the use of MSS systems to transmit medical diagnostic images from ambulances to hospitals during emergencies in rural locations. These types of applications require much higher bandwidths than typical (message) data applications and have not been incorporated in the estimates given in this section.
Use of Non-Geostationary Systems for Mobile-Satellite Services
In the late 1980's, proposals were advanced to use non-geostationary (non-GSO) satellites[EN157] for commercial MSS purposes. Two types of commercial Non-GSO systems have emerged: small, inexpensive data-only satellite systems using frequencies below 1 GHz, and large, high-capacity systems operating above 1 GHz.
The smaller capacity systems are presently authorized to operate in lower frequency bands (137 MHz, 149 MHz and 400 MHz). The first of these systems is now operating experimentally in the United States and in some other nations. A large market targeted by these systems in the United States is for automobile theft recovery, distress alerting, water level monitoring, agricultural uses and environmental monitoring activities. Three domestic companies have applied to operate Non-GSO systems operating below 1 GHz.
Large-scale Non-GSO systems propose to offer voice, data, and location services to hand-held terminals similar to cellular telephones. These systems could begin operating within a few years. Five domestic companies have applied to operate Non-GSO systems above 1 GHz.
MSS systems provide coverage to large areas of the Earth. Spacecraft weight and antenna technology presently limit the amount of frequency reuse possible in and between MSS systems. For example, operation of a geostationary MSS system over the North Atlantic may preclude the use of the same frequency set in most parts of the United States. Thus, the amount of spectrum required to support a given number of MSS users is large in comparison to the same number of users that can be served by highly developed terrestrial systems. However, the advantage of MSS is that traffic can be accommodated originating anywhere within the large coverage areas of the MSS satellite. Many countries are implementing MSS systems today, and these foreign systems may well impact the use of MSS spectrum available in the United States.
Comsat stated that an estimated 200 MHz is required for GSO MSS systems, worldwide, in the future. Spectrum projections out to the year 2010, made in 1991, showed a large increase in spectrum needed to serve the potential MSS market.[EN158] In Comsat's view, this 200 MHz does not include spectrum needed for voice service to hand-held devices as envisioned by FPLMTS and the prospective Big Non-GSO MSS systems.[EN159]
MSS systems providing service to hand-held devices are further constrained in the amount of frequency reuse that can presently be achieved. Fundamentally, the lack of high-gain satellite antenna discrimination is a limiting factor in the spectrum efficiency achievable with these systems. For example, present designs of big Non-GSO's generate at most a few hundred voice channels per megahertz over the United States. However, the MSS Non-GSO above 1 GHz applicants have been cautious in stating spectrum requirements beyond those in their initial FCC applications. The initial licenses would be limited to a maximum of 33 MHz.[EN160]
Non-GSO MSS systems below 1 GHz use considerably less spectrum than the Non-GSO systems using frequencies above 1 GHz because they are used for low data rate transmissions only. These systems should be capable of supporting large numbers of users in a few megahertz.
Several Federal MSS systems support U.S. military operations on a worldwide basis. These include GSO and non-GSO systems. Non-GSO systems can be in various higher orbits (medium orbit, intermediate orbit, or elliptical orbit). Federal systems operate in the 225-400 MHz, 7/8 GHz, 20/30 GHz and 20/44 GHz portions of the spectrum[EN161]. Beyond the use of Federally-operated MSS systems to support military operations, it is anticipated that the growing demand for MSS by Federal agencies will be met by commercial MSS providers.
Internationally, several frequency bands are allocated to commercial MSS. Additionally, there are several bands allocated to MSS on an ITU Regional basis. Currently in the United States only a subset of the worldwide allocated bands are available for commercial MSS systems; the 1525-1559, 1610-1626.5, 1626.5-1660.5 and 2483.5-2500 MHz bands and the 137-138, 148-150.05, 399.9-400.5, and the 400.15-401 MHz bands. AMSC stated that "even the substantial additional MSS allocations made at the 1992 WARC cannot be expected to alleviate the severe shortage of spectrum that constrains the development of MSS in the United States"[EN162] AMSC further stated that additional spectrum is urgently needed because the international coordination process has indicated that the United States is unlikely to gain access to a sufficient amount of the presently allocated spectrum to fully develop AMSC's currently planned system.[EN163]
The MSS industry perceives a shortage of MSS spectrum even taking into account the bands allocated at WARC-92. Many of the newly allocated bands are shared with other services and will not be available entirely to MSS. Further, MSS spectrum used by other countries, such as Mexico and Canada, cannot also be used by a U.S. system. More than 30 MSS systems around the world are in various stages of planning for the 28 MHz of spectrum presently authorized to AMSC in the United States.[EN164] Of the newly-allocated bands, only the 1525-1530, 1610-1626.5, and 2483.5-2500 MHz bands are readily available in the United States.[EN165] For commercial Non-GSO systems operating on frequencies below 1 GHz, there is approximately 4 MHz, shared among a number of radio services, that is currently available.
There are several factors that will determine whether additional spectrum is needed for MSS in the United States. The first is the extent to which MSS voice and data services using hand-held devices can successfully compete with terrestrially-delivered services.[EN166] A high level of acceptance of such MSS services would likely cause the present spectrum available for large-scale MSS (Non-GSO's and future GSO systems) to be inadequate. A second factor is the availability of the MSS spectrum allocated at WARC-92. The implementation of worldwide MSS systems will require at least the spectrum allocated at WARC-92 to account for the non-uniform implementation of MSS allocations within and between various administrations.[EN167] The third factor is that the spectrum efficiency of MSS systems is limited by the size of the space and terrestrial antennas employed. Improvements in MSS system efficiency will result primarily from larger spacecraft antennas that increase frequency reuse potential. There are plans to use very large antennas, generating many beams over an area the size of the continental United States, in future MSS systems.
It is assumed that the principal growth in MSS services in the United States over the next 10 years will be from the introduction of low-cost "personal" satellite-delivered telecommunications services. Existing MSS services will also experience growth during the next 10 years; new services will be primarily a voice-oriented service that supplements terrestrial cellular radiotelephone service. This MSS service is characterized by being able to use hand-held earth stations and will require new technologies to be employed, such as non-GSO satellite systems, in order to be offered.
An estimate of additional spectrum needed to accommodate this service in the next 10 years requires several assumptions to be made regarding this new, untried market. First, it is assumed that the service offerings will be dual-mode, in that the customer will automatically receive the lowest-cost option available, either MSS or terrestrial cellular-like service, including PCS services. We further assume that about three percent of cellular subscribers will use MSS offerings.
The estimate of additional spectrum for MSS is calculated as equal to the product of the number of subscribers, the number of channels per subscriber, the bandwidth per channel, and the reuse factor.[EN168] It is estimated that the cellular and cellular-like subscriber base will be in excess of 80 million by 2004.[EN169] An additional 0.9 million data-only and conventional MSS subscribers is estimated to use MSS services by 2004. This results in a total MSS user base of 3.3 million.[EN170]
With a first-generation MSS reuse factor of 0.67, the current 99 MHz of MSS spectrum will accommodate 1.48 million subscribers, leaving 1.82 million to be accommodated in additional, as yet un-allocated MSS spectrum. Assuming a second-generation reuse factor of 0.33, then approximately 60 MHz of additional MSS spectrum will be needed by 2004. It would be preferable for international compatibility and spectrum efficiency that this spectrum come from the bands allocated internationally at WARC-92 (1980-2010 MHz and 2170-2200 MHz).
For non-GSO MSS systems below 1 GHz, industry has recently estimated that an additional 7 MHz is required by the year 2000.[EN171] However, it is envisioned that this spectrum will be shared with terrestrial use.
An additional amount of spectrum, estimated to be on the order of 60 MHz, is needed to be available to meet U.S. mobile-satellite traffic requirements by the year 2004. This additional spectrum is needed to serve the several million new MSS subscribers envisioned for the period beginning around the year 2000. The principal service is expected to be as a supplement to terrestrial cellular and PCS in order to provide voice communications into areas where terrestrial systems will not operate. Additional spectrum also needs to be available for non-GSO MSS operating below 1 GHz. This requirement is on the order of a few Megahertz but can be shared with terrestrial systems. However, because of rapidly evolving nature of MSS technology and the uncertainty of market demand, this spectrum requirement should be monitored closely and modified accordingly in the future.
MSS systems typically use frequencies in bands above 3 GHz for links between the satellite and large earth stations. Mobile-satellite feeder links are included as part of the fixed-satellite service (FSS) and thus use bands allocated to the FSS. Feeder links complete the path from the mobile earth station to a large fixed earth station that connects to the PSTN. Feeder links are also used to control the satellite transponder. The amount of spectrum required for feeder links is large, using today's technology which employs a single feederlink beam antenna on the satellite. It is estimated that given the efficient reuse of service link spectrum that between 10 and 20 times as much feeder link as service link spectrum could be needed. Future systems may be able to reduce the amount of spectrum required by introducing reuse of the feeder link frequencies and possibly by using compression techniques involving satellite on-board signal processing.
Since large earth stations are used for the feeder links for GSO MSS systems, feeder links can be shared with other satellite and terrestrial services in existing FSS bands. Therefore, no additional spectrum is needed to be dedicated to GSO MSS feeder links. For non-GSO systems, sharing is more difficult. One likely approach is to use FSS bands in the reverse direction for non-GSO feeder links. In such bands there may be limited sharing opportunities for terrestrial services. The amount of spectrum required for non-GSO feeder links, assuming that 50 MHz of service link spectrum were used for such systems, could be 500 to 1000 MHz. This spectrum requirement should be satisfied in the existing FSS bands for the most part. Domestic and international efforts are underway to identify bands and sharing possibilities for MSS feeder links within existing FSS bands.[EN172] Some bands not presently allocated to the FSS are also being considered for non-GSO feeder links. Several non-GSO MSS applicants have requested spectrum for uplinks which would not be shared with other FSS systems[EN173]. Several other non-GSO systems have requested spectrum in the 20/30 GHz bands. The subject of MSS feeder links is on the agenda for the 1995 ITU World Radiocommunication Conference (WRC).
Recent studies indicate that in some cases multiple MSS system feederlinks can share the same spectrum.[EN174] Both forward band working (FBW) and reverse band working (RBW) of FSS Bands have been advocated by MSS industry representatives to accommodate the feeder link spectrum requirements within the current FSS allocations. If RBW provides better sharing prospects than FBW, the candidate FSS bands may have to be reallocated at a future WRC. Comments to the FCC indicated that spectrum needed for non-GSO feederlinks could be from 200 to 400 MHz, depending on the amount of intrasystem sharing possible.[EN175]
Preliminary analysis indicates that GSO MSS feeder links may be able to share compatibly with the FSS and that additional spectrum may not be required. For non-GSO feeder links, the emphasis has been on using RBW as a promising means for sharing with some FSS bands. However, industry has indicated that spectrum not shared with FSS for feederlink uplinks on the order of 200-400 MHz is needed for initial U.S. systems. This spectrum would, however, be shared with terrestrial systems. Studies are now being conducted that will provide more insight into spectrum requirements and sharing possibilities. The amount of spectrum needed for feederlinks in the United States depends on the number of Non-GSO systems implemented, the spectrum available for MSS service links (that is from the mobile to the satellite) and the amount of intra-MSS system reuse.